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Sample records for blue-enriched mueller-hinton agar

  1. Influence of different Mueller-Hinton agars and media age on Etest susceptibility testing of tigecycline.

    PubMed

    Tan, Thean Yen; Ng, Lily Siew Yong; Chen, Dorene Mei Mei

    2010-09-01

    This study investigated the effect of different Mueller-Hinton agars and media age on tigecycline MICs, obtained by Etest. Variations in MIC values on different Mueller-Hinton were noted, which may result in changes in categoric susceptibility. The use of stored Mueller-Hinton media had minimal effect on MIC values.

  2. Use of Mueller-Hinton broth and agar in the germ tube test.

    PubMed

    Mattei, Antonella Souza; Alves, Sydney Hartz; Severo, Cecília Bittencourt; Guazzelli, Luciana da Silva; Oliveira, Flávio de Mattos; Severo, Luiz Carlos

    2014-01-01

    Candida albicans is often isolated from clinical samples, thus its presumptive differentiation from other species of the same genus can be based on its ability to form the germ tube in human serum. Nevertheless, there are two other species that share this characteristic: C. dubliniensis and C. africana. The aim of this study was to compare four different substrates to perform the germ tube (GT) test. The Candida spp. isolates were identified using a manual system (135 C. albicans, 24 C. tropicalis and one C. dubliniensis). The germ tube test was performed with fresh, previously frozen serum and Mueller-Hinton (MH) broth and agar. GT was observed in 96% (130/136) of the isolates through the fresh serum technique, 94% (128/136) through previously frozen serum, 92% (125/136) in MH agar, and 90% (122/136) in MH broth. The sensitivity of each test was higher than 90%, with 100% specificity. Both the MH agar and broth were able to identify the true positives, and false positives were not found. However, some C. albicans isolates were not identified. MH agar and broth may be used in laboratory for the rapid presumptive identification of C. albicans, as an alternative method for germ tube test.

  3. A comparison of antibiotic disks from different sources on Quicolor and Mueller-Hinton agar media in evaluation of antibacterial susceptibility testing

    PubMed Central

    Saffari, Neda; Salmanzadeh-Ahrabi, Siavosh; Abdi-Ali, Ahya; Rezaei-Hemami, Mohsen

    2016-01-01

    Background and Objectives: Antibacterial susceptibility testing of clinical bacterial isolates through disk diffusion method plays a major role in antibacterial treatment. One of the main factors affecting the result of these tests is the type, structure and quality of the disks. The main objective of this study was to compare the agreement of antibiotic disks originated from three companies on Quicolor and Mueller-Hinton agar. Materials and Methods: Quicolor and Mueller-Hinton agar media were used in disk diffusion method. Seventy clinical isolates from Enterobacteriaceae family (21 Klebsiella spp., 36 Escherichia coli, 1 Enterobacter spp. and 12 Shigella spp.) were investigated in the study. After obtaining data, the results were interpreted as resistant, sensitive or intermediate. Kappa coefficient measured the agreement of two media. Coefficient of variation (CV) was also calculated for antibiotic disks. Results: The kappa agreement values for three types of antibiotic disks on Quicolor and Mueller-Hinton agar plates were good or excellent for all the examined antibiotics. CV values were also very satisfactory in the majority of cases. Conclusion: Antibiotic disks from three manufacturers can successfully be used on both Quicolor and Mueller-Hinton agar plates. PMID:28149489

  4. Evaluation of Mueller-Hinton-agar as a simple medium for the germ tube production of Candida albicans and Candida dubliniensis.

    PubMed

    Rimek, Dagmar; Fehse, Brigitte; Göpel, Petra

    2008-05-01

    Candida albicans is the most frequently isolated yeast species from clinical specimens. A classical rapid presumptive differentiation from non-albicans species is based on its ability to produce germ tubes after incubation in human serum. The only non-albicans Candida species producing germ tubes is Candida dubliniensis. In this study, we evaluated Mueller-Hinton-agar (MH-agar) as a medium for germ tube formation of C. albicans and C. dubliniensis. A total of 859 yeast isolates from stool samples, including 632 strains of C. albicans, 10 C. dubliniensis and 217 other yeast strains from 20 different species, were grown on Sabouraud glucose (2%) agar at 37 degrees C for 24-72 h. Species were identified by standard methods. For the germ tube test (GTT), an inoculum from a single colony was streaked onto a MH-agar plate and covered by a sterile coverslip. After incubation at 37 degrees C for 2 h, the MH plates were examined using a light microscope at x200. The GTT was positive in 578 of 632 C. albicans strains (sensitivity 91.5%), in six of 10 C. dubliniensis strains (sensitivity 60.0%), and in none of the other yeast strains. MH-agar is a suitable medium for the GTT and the presumptive identification of C. albicans. It is safer to use than human serum and is widely available in microbiology laboratories.

  5. Modified Hodge test using Mueller-Hinton agar supplemented with cloxacillin improves screening for carbapenemase-producing clinical isolates of Enterobacteriaceae.

    PubMed

    Takayama, Yoko; Adachi, Yuzuru; Nihonyanagi, Shin; Okamoto, Ryoichi

    2015-07-01

    Increasing numbers of clinical isolates of Enterobacteriaceae that produce carbapenemase are now being detected, with the most common carbapenemase found among Enterobacteriaceae in Japan being IMP-1-type metallo-β-lactamase. Clinical isolates of Enterobacteriaceae harbouring carbapenemases may be resistant to carbapenem antimicrobial agents, despite apparent in vitro susceptibility when tested according to Clinical and Laboratory Standards Institute criteria. We evaluated the prevalence of carbapenemase producers among isolates of Enterobacteriaceae at our hospital and assessed the performance of the modified Hodge test (MHT) for correctly identifying the phenotype. We studied 47 clinical isolates obtained between 2006 and 2010 for which the MIC of imipenem was 2 or 4 μg imipenem ml- 1. Antibacterial susceptibility testing was done for cephalosporins and carbapenems, the MHT was performed with meropenem and detection of the genes encoding IMP-1, VIM-2, KPC-2 and NDM-1-type metallo-β-lactamases was performed by PCR. Twelve isolates showed a positive result in the MHT with meropenem and were classified as carbapenemase producers. Of these 12 isolates, seven carried the gene for IMP-1 type, but not for VIM-2, KPC-2 or NDM-1 types. None of the carbapenemase genes tested were detected in the other five isolates. All five isolates were Enterobacter cloacae showing high resistance to ceftazidime and aztreonam. False-positive results were inhibited when Mueller-Hinton agar supplemented with 200 mg cloxacillin ml- 1 was used for the MHT. Five of 12 MHT-positive isolates were shown to have no carbapenemase genes and these isolates were high AmpC producers. Adding cloxacillin when performing the MHT prevented such false-positive results. The MHT with cloxacillin can overcome most problems related to detection of carbapenemases.

  6. Characterization of the selective inhibition of growth of virulent Legionella pneumophila by supplemented Mueller-Hinton medium.

    PubMed Central

    Catrenich, C. E.; Johnson, W.

    1989-01-01

    The phenotypic difference between virulent and avirulent Legionella pneumophila with regard to growth on supplemented Mueller-Hinton (SMH) agar was investigated. Defined populations of virulent and avirulent L. pneumophila were inoculated onto hybrid growth media containing the combination of SMH agar components with potassium phosphate-buffered charcoal-yeast extract agar. The casein acid hydrolysate component of SMH agar was found to be inhibitory to the growth of virulent but not avirulent cells. The selectively inhibitory component of the casein acid hydrolysate was identified as NaCl. Images PMID:2722245

  7. Comparison of cation-adjusted Mueller-Hinton broth with Iso-Sensitest broth for the NCCLS broth microdilution method.

    PubMed

    Koeth, L M; King, A; Knight, H; May, J; Miller, L A; Phillips, I; Poupard, J A

    2000-09-01

    Comparison of MIC results obtained in different parts of the world is currently difficult because of variations in methods. In this study, cation-adjusted Mueller-Hinton broth, the NCCLS-recommended medium, was compared with Iso-Sensitest broth, which is widely used in Europe. Microbroth dilution testing, using the NCCLS procedure, was performed on 124 Gram-positive (staphylococci and enterococci) and Gram-negative (Enterobacteriaceae and Pseudomonas aeruginosa) isolates from the CDC reference set, with the only variable being the medium used. Twelve antimicrobial agents were tested: amoxycillin-clavulanic acid, ampicillin, ciprofloxacin, erythromycin, gentamicin, imipenem, levofloxacin, oxacillin, gemifloxacin, trimethoprim- sulphamethoxazole, tetracycline and vancomycin. Vancomycin, erythromycin and oxacillin were only evaluated for the Gram-positive organisms. Trimethoprim-sulphamethoxazole was only evaluated for a subset of Gram-negative organisms because of off-scale results. The 124 isolates were tested in one American and one UK laboratory with two batches of cation-adjusted Mueller-Hinton broth and two of Iso-Sensitest broth. A statistical evaluation of the data used a 24 fully specified factorial analysis to determine if there were significant differences in results owing to Gram reaction, site of testing and type and/or batch of broth. In addition, the cumulative results for each antimicrobial agent in each broth were plotted against the range of MIC dilutions tested. MICs of ciprofloxacin, levofloxacin, gemifloxacin, gentamicin and tetracycline were slightly higher (half a doubling dilution) with Iso-Sensitest broth than with Mueller-Hinton broth. MIC results for the other antimicrobial agents were equivalent. Essential and category agreement rates were comparable for all agents (88.4-100% and 88.2-99.0%, respectively).

  8. Mueller-Hinton broth undergoes visible oxidative color changes in the presence of peroxidase and hydrogen peroxide.

    PubMed Central

    Galeazzi, L; Groppa, G; Giunta, S

    1990-01-01

    In the presence of peroxidase and hydrogen peroxide, Mueller-Hinton broth undergoes a slow but clearly detectable color change from pale yellow to dark yellow or brown. An investigation of this phenomenon led to the conclusion that it is the result of the oxidation of tyrosine, a major component of the broth. Indeed, tyrosine has long been known to oxidize upon treatment with peroxidase and hydrogen peroxide. The observations reported here, besides being curious for the clinical microbiologist, might deserve attention for the possible implications in the medium color darkening which sometimes happens during microbial growth. Images PMID:2172301

  9. Criteria for the interpretation of the pipemidic acid agar diffusion test by the Kirby-Bauer method.

    PubMed

    Grimm, H

    1983-01-01

    The antibiotic sensitivity of 296 strains of Pseudomonas aeruginosa and 294 isolates of other species was measured by the agar diffusion test with 20 micrograms pipemidic acid (Deblaston) discs on Mueller-Hinton agar by the Kirby-Bauer method. The correlation between inhibition zone diameter and minimal inhibitory concentration was worked out by regression analysis. In all bacterial species investigated, an inhibition zone of 14 mm or more indicates sensitivity to pipemidic acid. For Pseudomonas aeruginosa an intermediate zone of 11 to 13 mm is recommended.

  10. Agar disk diffusion (Bauer-Kirby) tests with various fastidious and nonfastidious reference (ATCC) strains: comparison of several agar media.

    PubMed

    Traub, W H; Leonhard, B

    1994-01-01

    Several agar media (Mueller-Hinton agar, MHA; diagnostic sensitivity test agar, DSTA; Schaedler agar, SchA; Todd-Hewitt agar with added yeast extract, THYA; Wilkins-Chalgren agar, WCA) were compared using the Bauer-Kirby agar disk diffusion test against six nonfastidious quality control strains: Staphylococcus aureus ATCC 25923 and ATCC 29213, Escherichia coli ATCC 25922 and ATCC 35218, Pseudomonas aeruginosa ATCC 27853, and Enterococcus faecalis ATCC 29212. MHA, DSTA, and THYA yielded essentially comparable inhibition zones. However, WCA and SchA antagonized cotrimoxazole and aminoglycoside antibiotics; furthermore, SchA antagonized polymyxin B, and both WCA and SchA antagonized imipenem against the P. aeruginosa strain, but not against the E. coli strains. Sheep blood-MHA (Bl-MHA), WCA, THYA, and DSTA were examined with Streptococcus pyogenes ATCC 19615, Streptococcus agalactiae ATCC 13813, and Streptococcus pneumoniae ATCC 6306. In comparison with Bl-MHA, both WCA and THYA yielded comparable inhibition zones against S. pyogenes; DSTA afforded suboptimal growth. DSTA yielded larger inhibition zones with the majority of antimicrobial drugs against S. agalactiae, whereas WCA and THYA enhanced the activity of oxacillin and penicillin G against this strain. S. pneumoniae strain ATCC 6306 grew well on Bl-MHA, yielded suboptimal growth on WCA and faint growth on THYA, and failed to grow on DSTA. Chocolate-supplemented sheep blood-MHA (CHOC-MHA) was compared with Haemophilus test medium (HTM), WCA with added NAD, and THYA with added hematin and NAD against Haemophilus influenzae strains ATCC 35056 and ATCC 49247. The activities of doxycycline and rifampin were enhanced against both strains by HTM, WCA+NAD, and THYA+hematin+NAD. Only WCA+NAD antagonized cotrimoxazole against both H. influenzae strains, an effect due to thymidine; however, HTM antagonized cotrimoxazole against S. aureus ATCC 25923 and E. coli ATCC 25922. It was concluded that Bl-MHA performed best for

  11. Morning and Evening Blue-Enriched Light Exposure Alters Metabolic Function in Normal Weight Adults

    PubMed Central

    Cheung, Ivy N.; Zee, Phyllis C.; Shalman, Dov; Malkani, Roneil G.; Kang, Joseph; Reid, Kathryn J.

    2016-01-01

    Increasing evidence points to associations between light-dark exposure patterns, feeding behavior, and metabolism. This study aimed to determine the acute effects of 3 hours of morning versus evening blue-enriched light exposure compared to dim light on hunger, metabolic function, and physiological arousal. Nineteen healthy adults completed this 4-day inpatient protocol under dim light conditions (<20lux). Participants were randomized to 3 hours of blue-enriched light exposure on Day 3 starting either 0.5 hours after wake (n = 9; morning group) or 10.5 hours after wake (n = 10; evening group). All participants remained in dim light on Day 2 to serve as their baseline. Subjective hunger and sleepiness scales were collected hourly. Blood was sampled at 30-minute intervals for 4 hours in association with the light exposure period for glucose, insulin, cortisol, leptin, and ghrelin. Homeostatic model assessment of insulin resistance (HOMA-IR) and area under the curve (AUC) for insulin, glucose, HOMA-IR and cortisol were calculated. Comparisons relative to baseline were done using t-tests and repeated measures ANOVAs. In both the morning and evening groups, insulin total area, HOMA-IR, and HOMA-IR AUC were increased and subjective sleepiness was reduced with blue-enriched light compared to dim light. The evening group, but not the morning group, had significantly higher glucose peak value during blue-enriched light exposure compared to dim light. There were no other significant differences between the morning or the evening groups in response to blue-enriched light exposure. Blue-enriched light exposure acutely alters glucose metabolism and sleepiness, however the mechanisms behind this relationship and its impacts on hunger and appetite regulation remain unclear. These results provide further support for a role of environmental light exposure in the regulation of metabolism. PMID:27191727

  12. Morning and Evening Blue-Enriched Light Exposure Alters Metabolic Function in Normal Weight Adults.

    PubMed

    Cheung, Ivy N; Zee, Phyllis C; Shalman, Dov; Malkani, Roneil G; Kang, Joseph; Reid, Kathryn J

    2016-01-01

    Increasing evidence points to associations between light-dark exposure patterns, feeding behavior, and metabolism. This study aimed to determine the acute effects of 3 hours of morning versus evening blue-enriched light exposure compared to dim light on hunger, metabolic function, and physiological arousal. Nineteen healthy adults completed this 4-day inpatient protocol under dim light conditions (<20lux). Participants were randomized to 3 hours of blue-enriched light exposure on Day 3 starting either 0.5 hours after wake (n = 9; morning group) or 10.5 hours after wake (n = 10; evening group). All participants remained in dim light on Day 2 to serve as their baseline. Subjective hunger and sleepiness scales were collected hourly. Blood was sampled at 30-minute intervals for 4 hours in association with the light exposure period for glucose, insulin, cortisol, leptin, and ghrelin. Homeostatic model assessment of insulin resistance (HOMA-IR) and area under the curve (AUC) for insulin, glucose, HOMA-IR and cortisol were calculated. Comparisons relative to baseline were done using t-tests and repeated measures ANOVAs. In both the morning and evening groups, insulin total area, HOMA-IR, and HOMA-IR AUC were increased and subjective sleepiness was reduced with blue-enriched light compared to dim light. The evening group, but not the morning group, had significantly higher glucose peak value during blue-enriched light exposure compared to dim light. There were no other significant differences between the morning or the evening groups in response to blue-enriched light exposure. Blue-enriched light exposure acutely alters glucose metabolism and sleepiness, however the mechanisms behind this relationship and its impacts on hunger and appetite regulation remain unclear. These results provide further support for a role of environmental light exposure in the regulation of metabolism.

  13. Inaccuracy of the disk diffusion method compared with the agar dilution method for susceptibility testing of Campylobacter spp.

    PubMed

    Lehtopolku, Mirva; Kotilainen, Pirkko; Puukka, Pauli; Nakari, Ulla-Maija; Siitonen, Anja; Eerola, Erkki; Huovinen, Pentti; Hakanen, Antti J

    2012-01-01

    The agar dilution method has been standardized by the CLSI for the susceptibility testing of Campylobacter species, and according to these standards, the disk diffusion method should be used only in screening for macrolide and ciprofloxacin resistance. Nevertheless, the disk diffusion test is currently widely used, since it is easy to perform in clinical microbiology laboratories. In this study, the disk diffusion method was compared to the agar dilution method by analyzing the in vitro activities of seven antimicrobial agents against 174 Campylobacter strains collected in Finland between 2003 and 2008. Recommendations of the CLSI were followed using Mueller-Hinton agar plates with 5% of sheep blood. For each strain, the disk diffusion tests were performed two to four times. Of the 33 erythromycin-resistant strains (MIC, ≥16 μg/ml), 24 (73%) constantly showed a 6-mm erythromycin inhibition zone (i.e., no inhibition), while for seven strains the inhibition zone varied from 6 to 44 mm in repeated measurements. Among the 141 erythromycin-susceptible strains (MIC, <16 μg/ml), erythromycin inhibition zones varied between 6 and 61 mm. Of the 87 ciprofloxacin-resistant strains, 47 (54%) showed 6-mm inhibition zones, while 40 strains showed inhibition zones between 6 and 60 mm. Significant differences between the repetitions were observed in the disk diffusion for all antimicrobial agents and all strains except for the macrolide-resistant strains regarding the macrolides. For 17 (10%) strains, the variation in repeated measurements was substantial. These results show that the disk diffusion method may not be a reliable tool for the susceptibility testing of Campylobacter spp. Further studies are needed to assess whether the disk diffusion test could be improved or whether all susceptibilities of campylobacters should be tested using an MIC-based method.

  14. Practical agar-based disk potentiation test for detection of fosfomycin-nonsusceptible Escherichia coli clinical isolates producing glutathione S-transferases.

    PubMed

    Nakamura, Genki; Wachino, Jun-Ichi; Sato, Natsumi; Kimura, Kouji; Yamada, Keiko; Jin, Wanchun; Shibayama, Keigo; Yagi, Tetsuya; Kawamura, Kumiko; Arakawa, Yoshichika

    2014-09-01

    The number of reports concerning Escherichia coli clinical isolates that produce glutathione S-transferases responsible for fosfomycin resistance (FR-GSTs) has been increasing. We have developed a disk-based potentiation test in which FR-GST producers expand the growth inhibition zone around a Kirby-Bauer disk containing fosfomycin in combination with sodium phosphonoformate (PPF). PPF, an analog of fosfomycin, is a transition-state inhibitor of FosA(PA), a type of FR-GST from Pseudomonas aeruginosa. Considering its mechanism of action, PPF was expected to inhibit a variety of FR-GSTs. In the presence of PPF, zone enlargement around the disk containing fosfomycin was observed for FosA3-, FosA4-, and FosC2-producing E. coli clinical isolates. Moreover, the growth inhibition zone was remarkably enlarged when the Mueller-Hinton (MH) agar plate contained 25 μg/ml glucose-6-phosphate (G6P). When we retrospectively tested 12 fosfomycin-resistant (MIC, ≥256 μg/ml) E. coli clinical isolates from our hospital with the potentiation test, 6 FR-GST producers were positive phenotypically by potentiation disk and were positive for FR-GST genes: 5 harbored fosA3 and 1 harbored fosA4. To identify the production of FR-GSTs, we set the provisional cutoff value, 5-mm enlargement, by adding PPF to a fosfomycin disk on the MH agar plates containing G6P. Our disk-based potentiation test reliably identifies FR-GST producers and can be performed easily; therefore, it will be advantageous in epidemiological surveys and infection control of fosfomycin-resistant bacteria in clinical settings.

  15. The impact of bright artificial white and 'blue-enriched' light on sleep and circadian phase during the polar winter.

    PubMed

    Mottram, Victoria; Middleton, Benita; Williams, Peter; Arendt, Josephine

    2011-03-01

    Delayed sleep phase (and sometimes free-run) is common in the Antarctic winter (no natural sunlight) and optimizing the artificial light conditions is desirable. This project evaluated sleep when using 17,000 K blue-enriched lamps compared with standard white lamps (5000 K) for personal and communal illumination. Base personnel, 10 males, five females, 32.5±8 years took part in the study. From 24 March to 21 September 2006 light exposure alternated between 4-5-week periods of standard white (5000 K) and blue-enriched lamps (17,000 K), with a 3-week control before and after extra light. Sleep and light exposure were assessed by actigraphy and sleep diaries. General health (RAND 36-item questionnaire) and circadian phase (urinary 6-sulphatoxymelatonin rhythm) were evaluated at the end of each light condition. Direct comparison (rmanova) of blue-enriched light with white light showed that sleep onset was earlier by 19 min (P=0.022), and sleep latency tended to be shorter by 4 min (P=0.065) with blue-enriched light. Analysing all light conditions, control, blue and white, again provided evidence for greater efficiency of blue-enriched light compared with white (P<0.05), but with the best sleep timing, duration, efficiency and quality in control natural light conditions. Circadian phase was earlier on average in midwinter blue compared with midwinter white light by 45 min (P<0.05). Light condition had no influence on general health. We conclude that the use of blue-enriched light had some beneficial effects, notably earlier sleep, compared with standard white light during the polar winter.

  16. Ocular exposure to blue-enriched light has an asymmetric influence on neural activity and spatial attention

    PubMed Central

    Newman, Daniel P.; Lockley, Steven W.; Loughnane, Gerard M.; Martins, Ana Carina P.; Abe, Rafael; Zoratti, Marco T. R.; Kelly, Simon P.; O’Neill, Megan H.; Rajaratnam, Shantha M. W.; O’Connell, Redmond G.; Bellgrove, Mark A.

    2016-01-01

    Brain networks subserving alertness in humans interact with those for spatial attention orienting. We employed blue-enriched light to directly manipulate alertness in healthy volunteers. We show for the first time that prior exposure to higher, relative to lower, intensities of blue-enriched light speeds response times to left, but not right, hemifield visual stimuli, via an asymmetric effect on right-hemisphere parieto-occipital α-power. Our data give rise to the tantalising possibility of light-based interventions for right hemisphere disorders of spatial attention. PMID:27291291

  17. Performance of the EUCAST disk diffusion method, the CLSI agar screen method, and the Vitek 2 automated antimicrobial susceptibility testing system for detection of clinical isolates of Enterococci with low- and medium-level VanB-type vancomycin resistance: a multicenter study.

    PubMed

    Hegstad, Kristin; Giske, Christian G; Haldorsen, Bjørg; Matuschek, Erika; Schønning, Kristian; Leegaard, Truls M; Kahlmeter, Gunnar; Sundsfjord, Arnfinn

    2014-05-01

    Different antimicrobial susceptibility testing methods to detect low-level vancomycin resistance in enterococci were evaluated in a Scandinavian multicenter study (n=28). A phenotypically and genotypically well-characterized diverse collection of Enterococcus faecalis (n=12) and Enterococcus faecium (n=18) strains with and without nonsusceptibility to vancomycin was examined blindly in Danish (n=5), Norwegian (n=13), and Swedish (n=10) laboratories using the EUCAST disk diffusion method (n=28) and the CLSI agar screen (n=18) or the Vitek 2 system (bioMérieux) (n=5). The EUCAST disk diffusion method (very major error [VME] rate, 7.0%; sensitivity, 0.93; major error [ME] rate, 2.4%; specificity, 0.98) and CLSI agar screen (VME rate, 6.6%; sensitivity, 0.93; ME rate, 5.6%; specificity, 0.94) performed significantly better (P=0.02) than the Vitek 2 system (VME rate, 13%; sensitivity, 0.87; ME rate, 0%; specificity, 1). The performance of the EUCAST disk diffusion method was challenged by differences in vancomycin inhibition zone sizes as well as the experience of the personnel in interpreting fuzzy zone edges as an indication of vancomycin resistance. Laboratories using Oxoid agar (P<0.0001) or Merck Mueller-Hinton (MH) agar (P=0.027) for the disk diffusion assay performed significantly better than did laboratories using BBL MH II medium. Laboratories using Difco brain heart infusion (BHI) agar for the CLSI agar screen performed significantly better (P=0.017) than did those using Oxoid BHI agar. In conclusion, both the EUCAST disk diffusion and CLSI agar screening methods performed acceptably (sensitivity, 0.93; specificity, 0.94 to 0.98) in the detection of VanB-type vancomycin-resistant enterococci with low-level resistance. Importantly, use of the CLSI agar screen requires careful monitoring of the vancomycin concentration in the plates. Moreover, disk diffusion methodology requires that personnel be trained in interpreting zone edges.

  18. Chronic artificial blue-enriched white light is an effective countermeasure to delayed circadian phase and neurobehavioral decrements.

    PubMed

    Najjar, Raymond P; Wolf, Luzian; Taillard, Jacques; Schlangen, Luc J M; Salam, Alex; Cajochen, Christian; Gronfier, Claude

    2014-01-01

    Studies in Polar Base stations, where personnel have no access to sunlight during winter, have reported circadian misalignment, free-running of the sleep-wake rhythm, and sleep problems. Here we tested light as a countermeasure to circadian misalignment in personnel of the Concordia Polar Base station during the polar winter. We hypothesized that entrainment of the circadian pacemaker to a 24-h light-dark schedule would not occur in all crew members (n = 10) exposed to 100-300 lux of standard fluorescent white (SW) light during the daytime, and that chronic non-time restricted daytime exposure to melanopsin-optimized blue-enriched white (BE) light would establish an a stable circadian phase, in participants, together with increased cognitive performance and mood levels. The lighting schedule consisted of an alternation between SW lighting (2 weeks), followed by a BE lighting (2 weeks) for a total of 9 weeks. Rest-activity cycles assessed by actigraphy showed a stable rest-activity pattern under both SW and BE light. No difference was found between light conditions on the intra-daily stability, variability and amplitude of activity, as assessed by non-parametric circadian analysis. As hypothesized, a significant delay of about 30 minutes in the onset of melatonin secretion occurred with SW, but not with BE light. BE light significantly enhanced well being and alertness compared to SW light. We propose that the superior efficacy of blue-enriched white light versus standard white light involves melanopsin-based mechanisms in the activation of the non-visual functions studied, and that their responses do not dampen with time (over 9-weeks). This work could lead to practical applications of light exposure in working environment where background light intensity is chronically low to moderate (polar base stations, power plants, space missions, etc.), and may help design lighting strategies to maintain health, productivity, and personnel safety.

  19. Chronic Artificial Blue-Enriched White Light Is an Effective Countermeasure to Delayed Circadian Phase and Neurobehavioral Decrements

    PubMed Central

    Najjar, Raymond P.; Wolf, Luzian; Taillard, Jacques; Schlangen, Luc J. M.; Salam, Alex

    2014-01-01

    Studies in Polar Base stations, where personnel have no access to sunlight during winter, have reported circadian misalignment, free-running of the sleep-wake rhythm, and sleep problems. Here we tested light as a countermeasure to circadian misalignment in personnel of the Concordia Polar Base station during the polar winter. We hypothesized that entrainment of the circadian pacemaker to a 24-h light-dark schedule would not occur in all crew members (n = 10) exposed to 100–300 lux of standard fluorescent white (SW) light during the daytime, and that chronic non-time restricted daytime exposure to melanopsin-optimized blue-enriched white (BE) light would establish an a stable circadian phase, in participants, together with increased cognitive performance and mood levels. The lighting schedule consisted of an alternation between SW lighting (2 weeks), followed by a BE lighting (2 weeks) for a total of 9 weeks. Rest-activity cycles assessed by actigraphy showed a stable rest-activity pattern under both SW and BE light. No difference was found between light conditions on the intra-daily stability, variability and amplitude of activity, as assessed by non-parametric circadian analysis. As hypothesized, a significant delay of about 30 minutes in the onset of melatonin secretion occurred with SW, but not with BE light. BE light significantly enhanced well being and alertness compared to SW light. We propose that the superior efficacy of blue-enriched white light versus standard white light involves melanopsin-based mechanisms in the activation of the non-visual functions studied, and that their responses do not dampen with time (over 9-weeks). This work could lead to practical applications of light exposure in working environment where background light intensity is chronically low to moderate (polar base stations, power plants, space missions, etc.), and may help design lighting strategies to maintain health, productivity, and personnel safety. PMID:25072880

  20. Antimicrobial Susceptibility of Flavobacterium psychrophilum from Chilean Salmon Farms and Their Epidemiological Cut-Off Values Using Agar Dilution and Disk Diffusion Methods

    PubMed Central

    Miranda, Claudio D.; Smith, Peter; Rojas, Rodrigo; Contreras-Lynch, Sergio; Vega, J. M. Alonso

    2016-01-01

    Flavobacterium psychrophilum is the most important bacterial pathogen for freshwater farmed salmonids in Chile. The aims of this study were to determine the susceptibility to antimicrobials used in fish farming of Chilean isolates and to calculate their epidemiological cut-off (COWT) values. A number of 125 Chilean isolates of F. psychrophilum were isolated from reared salmonids presenting clinical symptoms indicative of flavobacteriosis and their identities were confirmed by 16S rRNA polymerase chain reaction. Susceptibility to antibacterials was tested on diluted Mueller-Hinton by using an agar dilution MIC method and a disk diffusion method. The COWT values calculated by Normalized Resistance Interpretation (NRI) analysis allow isolates to be categorized either as wild-type fully susceptible (WT) or as manifesting reduced susceptibility (NWT). When MIC data was used, NRI analysis calculated a COWT of ≤0.125, ≤2, and ≤0.5 μg mL-1 for amoxicillin, florfenicol, and oxytetracycline, respectively. For the quinolones, the COWT were ≤1, ≤0.5, and ≤0.125 μg mL-1 for oxolinic acid, flumequine, and enrofloxacin, respectively. The disk diffusion data sets obtained in this work were extremely diverse and were spread over a wide range. For the quinolones there was a close agreement between the frequencies of NWT isolates calculated using MIC and disk data. For oxolinic acid, flumequine, and enrofloxacin the frequencies were 45, 39, and 38% using MIC data, and 42, 41, and 44%, when disk data were used. There was less agreement with the other antimicrobials, because NWT frequencies obtained using MIC and disk data, respectively, were 24 and 10% for amoxicillin, 8 and 2% for florfenicol, and 70 and 64% for oxytetracycline. Considering that the MIC data was more precise than the disk diffusion data, MIC determination would be the preferred method for susceptibility testing for this species and the NWT frequencies derived from the MIC data sets should be considered

  1. Antimicrobial Susceptibility of Flavobacterium psychrophilum from Chilean Salmon Farms and Their Epidemiological Cut-Off Values Using Agar Dilution and Disk Diffusion Methods.

    PubMed

    Miranda, Claudio D; Smith, Peter; Rojas, Rodrigo; Contreras-Lynch, Sergio; Vega, J M Alonso

    2016-01-01

    Flavobacterium psychrophilum is the most important bacterial pathogen for freshwater farmed salmonids in Chile. The aims of this study were to determine the susceptibility to antimicrobials used in fish farming of Chilean isolates and to calculate their epidemiological cut-off (COWT) values. A number of 125 Chilean isolates of F. psychrophilum were isolated from reared salmonids presenting clinical symptoms indicative of flavobacteriosis and their identities were confirmed by 16S rRNA polymerase chain reaction. Susceptibility to antibacterials was tested on diluted Mueller-Hinton by using an agar dilution MIC method and a disk diffusion method. The COWT values calculated by Normalized Resistance Interpretation (NRI) analysis allow isolates to be categorized either as wild-type fully susceptible (WT) or as manifesting reduced susceptibility (NWT). When MIC data was used, NRI analysis calculated a COWT of ≤0.125, ≤2, and ≤0.5 μg mL(-1) for amoxicillin, florfenicol, and oxytetracycline, respectively. For the quinolones, the COWT were ≤1, ≤0.5, and ≤0.125 μg mL(-1) for oxolinic acid, flumequine, and enrofloxacin, respectively. The disk diffusion data sets obtained in this work were extremely diverse and were spread over a wide range. For the quinolones there was a close agreement between the frequencies of NWT isolates calculated using MIC and disk data. For oxolinic acid, flumequine, and enrofloxacin the frequencies were 45, 39, and 38% using MIC data, and 42, 41, and 44%, when disk data were used. There was less agreement with the other antimicrobials, because NWT frequencies obtained using MIC and disk data, respectively, were 24 and 10% for amoxicillin, 8 and 2% for florfenicol, and 70 and 64% for oxytetracycline. Considering that the MIC data was more precise than the disk diffusion data, MIC determination would be the preferred method for susceptibility testing for this species and the NWT frequencies derived from the MIC data sets should be

  2. Improvement in routine detection of colistin resistance in E. coli isolated in veterinary diagnostic laboratories.

    PubMed

    Jouy, Eric; Haenni, Marisa; Le Devendec, Laëtitia; Le Roux, Aurélie; Châtre, Pierre; Madec, Jean-Yves; Kempf, Isabelle

    2017-01-01

    We have developed a phenotypic method suited to the systematic screening of resistance to colistin in E. coli, including those with the mcr-1 gene, by the absence of an inhibition zone after an application of a single drop of 8mg/L colistin solution on a previously inoculated Mueller-Hinton agar.

  3. Electro-osmosis in gels: Application to Agar-Agar

    NASA Astrophysics Data System (ADS)

    Cherblanc, Fabien; Boscus, Jérôme; Bénet, Jean-Claude

    2008-10-01

    Widely used in food- and bio-engineering as a reference material, Agar-Agar gel is the focus of an experimental investigation concerning the electro-osmosis phenomenon. After presenting the experimental methods, one trial is discussed in detail. A fair reproducibility of results is obtained, and the averaged electro-osmotic permeability is provided. This value lies in the range generally measured on various kind of soils, even if Agar-Agar gel does not share any micro-structural characteristics with soils. To cite this article: F. Cherblanc et al., C. R. Mecanique 336 (2008).

  4. Gravimorphogenesis in agarics.

    PubMed

    Moore, D; Hock, B; Greening, J P; Kern, V D; Novak Frazer, L; Monzer, J

    1996-03-01

    The shape changes which occur in agaric fruit bodies in response to change in the direction of gravity, usually referred to as gravitropism are morphogenetic changes. Our interest in what we prefer to call gravimorphogenesis is to use it to examine morphogenesis experimentally. We are examining two agarics, Coprinus cinereus and Flammulina velutipes, and applying the best available technologies, including video analysis, all forms of electron microscopy, computer-aided image analysis and experiments in orbit in Spacelab. Responses to gravity of the two organisms differ in ways which can be related to their ecological and structural adaptations. C. cinereus reacts extremely rapidly; its fruit body can regain the vertical within 3 h of being placed horizontal, whereas F. velutipes requires 12 h to bend through 90 degrees. The fungi also differ in the bulk of tissue involved in the response. In Coprinus, a zone extending several cm down from the apex is normally involved in bending. In Flammulina, gravisensing is limited to a region just a few mm immediately below the cap, although curvature is performed in a zone of up to 2 cm below. Flammulina cultures were flown on the Spacelab D-2 mission in 1993, and fruit body disorientation in orbit provides the first definitive proof that 'gravitropism' really is a response to the unidirectional gravity vector. Experiments with different clinostat rotation rates in Flammulina indicate that the perception threshold is about 10(-4) x g. Analysis of different times of exposure to an altered gravity vector prior to clinorotation in Coprinus reveals that the perception time is 7 minutes and that continued response requires continued exposure. Cell size determinations in Coprinus demonstrate that cells of the stem increase in length, not diameter, to produce the growth differential. In Flammulina a unique population of highly electron-transparent microvacuoles changes in distribution; decreasing in upper cells and increasing in the

  5. 21 CFR 184.1115 - Agar-agar.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Agar-agar. 184.1115 Section 184.1115 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) DIRECT FOOD SUBSTANCES AFFIRMED AS GENERALLY RECOGNIZED AS SAFE Listing of...

  6. Detection of Salmonella C1, D and V1 Antigens, by Coagglutination, in Blood Cultures from Patients with Salmonella Infections

    DTIC Science & Technology

    1980-01-01

    on Mueller-Hinton agar at 37C were prcsent, Klig!cr Iron (KIA), lysine iron , for 18 hours. The method of Edwards and motility indole ornithine and urea...DCLS) plated agar media Preparation of the stabilized protein A-rich (Oxoid,London) were inoculated with aliquots Staphylococcus: A Cowan I strain... agar media Larson (1974) was used to prepare stabilized (Difco) were then inoculated with growth cells. Basically, the confluent growth was from the

  7. In Vitro Susceptibilities of Bordetella pertussis and Bordetella parapertussis to Two Ketolides (HMR 3004 and HMR 3647), Four Macrolides (Azithromycin, Clarithromycin, Erythromycin A, and Roxithromycin), and Two Ansamycins (Rifampin and Rifapentine)

    PubMed Central

    Hoppe, Jörg E.; Bryskier, André

    1998-01-01

    When tested by agar dilution on Mueller-Hinton agar supplemented with 5% horse blood, the ketolides HMR 3004 and HMR 3647 were slightly more active (MIC at which 90% of the isolates were inhibited [MIC90], 0.03 μg/ml) against Bordetella pertussis than azithromycin, clarithromycin, erythromycin A, and roxithromycin. Azithromycin (MIC90, 0.06 μg/ml) was the most active compound against B. parapertussis. Rifampin and rifapentine were considerably less active. PMID:9559823

  8. Virulent to avirulent conversion of Legionnaires' disease bacterium (Legionella pneumophila)--its effect on isolation techniques.

    PubMed

    McDade, J E; Shepard, C C

    1979-06-01

    Suspensions of the Legionnaries' disease bacterium (Legionella pneumophila; LDB) were prepared from the yolk sacs of infected egg embryos, the spleens of infected guinea pigs, and cultures of the organism propagated on enriched Mueller-Hinton agar. Each suspension was titrated to determine the number of bacterial colonies (cfu), yolk sac 50% lethal doses (YSLD50), guinea pig 50% infectious doses (GPID50), and guinea pig 50% lethal doses (GPLD50) produced by 1 ml of inoculum. The numbers of cfu/YSLD50, GPID50, and GPLD50 were then calculated for each suspension. The suspension from yolk sacs had 1 cfu/YSLD50 and 10 cfu/GPID50. The suspension from spleens of guinea pigs also had 1 cfu/YSLD50. Organisms propagated on Mueller-Hinton agar, however, had greater than 10(7) cfu/YSLD50 and 10(5) cfu/GPID50. Thus, the LDB lost virulence when it was cultivated on agar. Guinea pigs vaccinated either subcutaneously or intraperitoneally with LDB grown on Mueller-Hinton agar resisted challenge with virulent LDB.

  9. Identification of Enterobacteriaceae and detection of carbapenemases from positive blood cultures by combination of MALDI-TOF MS and Carba NP performed after four hour subculture in Mueller Hinton.

    PubMed

    Fernández, Javier; Rodríguez-Lucas, Carlos; Fernández-Suárez, Jonathan; Vazquez, Fernando; Rodicio, M Rosario

    2016-10-01

    A new protocol for Enterobacteriaceae identification and detection of carbapenemase-producing isolates from blood cultures by combining MALDI-TOF MS and the Carba NP test has been evaluated. Bacterial identification was correct in 129 of the 130 isolates tested while the Carba NP detected 28 out of the 29 carbapenemase producers.

  10. The physicochemical property characterization of agar acetate.

    PubMed

    Xia, Kai; Liu, Xin; Zhao, Jingkun; Zhang, Xiaodong

    2014-09-22

    A series of agar acetates with different degree of substitution (DS) were prepared, and their properties were determined and analyzed. The results showed that the gelling temperature, the gel melting temperature, the gel strength, the gel hardness, the gel fracturability, the gel springiness and the solution apparent viscosity of agar acetates all decreased except that their gel cohesiveness increased with the increase of DS. The variation process of agar molecules in solution from coil to helix could be also observed by measuring solution optical rotation in a lower concentration at which even the solution could not form a gel. The gel skeleton structures of agar acetates were of porous network structures, and the pores became smaller and denser with the increase of DS. After acetylation, the water holding capacity of the agar was improved, but its thermal stability was lowered.

  11. Some Experiments With Agar-Grown Seedlings

    ERIC Educational Resources Information Center

    Freeland, P. W.

    1973-01-01

    Two percent agar gel is reported as a better medium for germination and growth studies. Students can be encouraged to undertake many simple experiments and make precise observations by using this medium. (PS)

  12. Morphological development of Morchella conica mycelium on different agar media.

    PubMed

    Guler, P; Ozkaya, E G

    2009-07-01

    The present study presents the development of mycelium of Morchella conica where different concentration of sucrose added at different agar media. For this sucrose have been added as 0.25, 0.50, 0.75, 1.00 and 1.25% concentration to wheat agar potato dextrose agar malt extract agar and complete medium yeast agar The radial growth speed, morphologic specifications, radial growth radius and pigmentation of mycelium were taken as criteria, the development period of mycelium in wheat agar was completed in 4 days and mycelium were very thin. The colonization period of the mycelium was determined; 7 days in potato dextrose agar 5 days in malt extract agar and 5 days at complete medium yeast agar. The development of the mycelium; at potato dextrose agar was dense and circular; at malt extract agar and at completed medium yeast agar was rhizomorphic. Mycelium has developed very well at sucrose medium and formed creamy and light yellow pigmentation.

  13. Pigments of fly agaric (Amanita muscaria).

    PubMed

    Stintzing, Florian; Schliemann, Willibald

    2007-01-01

    The complex pigment pattern of fly agaric (Amanita muscaria) cap skins has been studied by LC-DAD and mass spectrometry. Among the betaxanthins the corresponding derivatives of serine, threonine, ethanolamine, alanine, Dopa, phenylalanine and tryptophan are reported for the first time to contribute to the pigment pattern of fly agarics. Betalamic acid, the chromophoric precursor of betaxanthins and betacyanins, muscaflavin and seco-dopas were also detected. Furthermore, the red-purple muscapurpurin and the red muscarubrin were tentatively assigned while further six betacyanin-like components could not be structurally allocated. Stability studies indicated a high susceptibility of pigment extracts to degradation which led to rapid colour loss thus rendering a complete characterization of betacyanin-like compounds impossible at present. Taking into account these difficulties the presented results may be a starting point for a comprehensive characterization of the pigment composition of fly agarics.

  14. Standard operating procedure to prepare agar phantoms

    NASA Astrophysics Data System (ADS)

    Souza, R. M.; Santos, T. Q.; Oliveira, D. P.; Souza, R. M.; Alvarenga, A. V.; Costa-Felix, R. P. B.

    2016-07-01

    Agar phantoms are widely used as soft tissue mimics and some preparation techniques are described in the literature. There are also standards that describe the recipe of a soft tissue mimicking material (TMM). However some details of manufacture process are not clearly defined. The standardization of the phantom's preparation can produce a metrological impact on the results of the acoustic properties measured. In this direction, this paper presents a standard operating procedure (SOP) to prepare the agar TMM described on the IEC 60601-237.

  15. Use of agar agar stabilized milled zero-valent iron particles for in situ groundwater remediation

    NASA Astrophysics Data System (ADS)

    Schmid, Doris; Velimirović, Milica; Wagner, Stephan; Micić Batka, Vesna; von der Kammer, Frank; Hofmann, Thilo

    2015-04-01

    A major obstacle for use of nanoscale zero-valent iron (nZVI) particles as a nontoxic material for effective in situ degradation of chlorinated aliphatic hydrocarbons (CAHs) is the high production cost. For that reason, submicro-scale milled zero-valent iron particles were recently developed (milled ZVI, UVR-FIA, Germany) by grinding macroscopic raw materials of elementary iron as a cheaper alternative to products produced by solid-state reduction. However, milled ZVI particles tend to aggregate and due to the rather large particle size (d50= 11.9 µm) also rapidly sediment. To prevent aggregation and consequently sedimentation of milled ZVI particles and therefore improve the mobility after in situ application, the use of a stabilizer is considered in literature as a most promising option. In this study, milled ZVI particles (1 g L-1 of particle concentration) were stabilized by environmentally friendly polymer agar agar (>0.5 g L-1), which had a positive impact on the milled ZVI stability. Sedimentation rate was significantly decreased by increasing the suspension viscosity. Column transport experiments were performed for bare and agar agar stabilized milled ZVI particles in commercially available fine grained quartz sand (DORSILIT® Nr.8, Gebrüder Dorfner GmbH Co, Germany) and different porous media collected from brownfields. The experiments were carried out under field relevant injection conditions of 100 m d-1. The maximal travel distance (LT) of less than 10 cm was determined for non-stabilized suspension in fine grained quartz sand, while agar agar (1 g L-1) stabilized milled ZVI suspension revealed LT of 12 m. Similar results were observed for porous media from brownfields showing that mobility of agar agar stabilized particle suspensions was significantly improved compared to bare particles. Based on the mobility data, agar agar stabilized milled zero-valent iron particles could be used for in situ application. Finally, lab-scale batch degradation

  16. Laboratory identification of Haemophilus influenzae: effects of basal media on the results of the satellitism test and evaluation of the RapID NH system.

    PubMed Central

    Doern, G V; Chapin, K C

    1984-01-01

    The effects of four different basal media, tryptic soy agar, brain heart infusion agar, nutrient agar, and Mueller-Hinton agar, were investigated with respect to the identification of Haemophilus influenzae with a satellitism test in which X and V growth factors were supplied by factor-impregnated filter paper strips. A total of 187 recent clinical isolates of H. influenzae were examined. Of these, 179 strains (95.7%) were correctly identified with tryptic soy agar, 173 (92.5%) with brain heart infusion agar, 105 (56.1%) with nutrient agar, and 133 (71.1%) with Mueller-Hinton agar. Failure to obtain a correct identification was usually the result of satelliting growth around V factor-containing strips, possibly due to the presence of trace amounts of hemin in the basal media, or was because of an absence of growth due to nutritional deficiencies in the basal media. All 187 H. influenzae strains were also examined with a new biochemical and chromogenic substrate micromethod, the RapID NH system (Innovative Diagnostics Systems, Inc., Decatur, Ga.). A total of 168 (89.8%) strains were correctly identified with this system. PMID:6333435

  17. Ultrasonic backscatter coefficients for weakly scattering, agar spheres in agar phantoms

    PubMed Central

    King, Michael R.; Anderson, Janelle J.; Herd, Maria-Teresa; Ma, Darryl; Haak, Alexander; Wirtzfeld, Lauren A.; Madsen, Ernest L.; Zagzebski, James A.; Oelze, Michael L.; Hall, Timothy J.; O’Brien, William D.

    2010-01-01

    Applicability of ultrasound phantoms to biological tissue has been limited because most phantoms have generally used strong scatterers. The objective was to develop very weakly scattering phantoms, whose acoustic scattering properties are likely closer to those of tissues and then compare theoretical simulations and experimental backscatter coefficient (BSC) results. The phantoms consisted of agar spheres of various diameters (nominally between 90 and 212 μm), containing ultrafiltered milk, suspended in an agar background. BSC estimates were performed at two institutions over the frequency range 1–13 MHz, and compared to three models. Excellent agreement was shown between the two laboratory results as well as with the three models. PMID:20707460

  18. Biological treatment of textile dyes by agar-agar immobilized consortium in a packed bed reactor.

    PubMed

    Patel, Yogesh; Gupte, Akshaya

    2015-03-01

    The decolorization of Acid Maroon V was investigated using bacterial consortium EDPA containing Enterobacter dissolvens AGYP1 and Pseudomonas aeruginosa AGYP2 immobilized in different entrapment matrices. The consortium displayed 96% removal of dye (100 mg/l) within 6 h when immobilized in agar-agar. Under optimum concentrations of agar-agar (3.0% w/v) and cell biomass (0.9 g% w/v), the consortium displayed decolorization for 18 successive batches of Acid Maroon V and also decolorized 14 other different textile dyes. A packed bed reactor under batch mode showed 89% decolorization of dye after 56 repetitive cycles. Under continuous flow mode, maximum color removal was achieved with bed length of 36 cm, hydraulic retention time of 2.66 h, and dye concentration of 100 mg/l. Additionally, the reactor decolorized relatively higher concentrations (100-2000 mg/l) of dye. The synthetic dye wastewater containing five textile dyes was decolorized 92% with 62% COD reduction using an immobilized consortium.

  19. Screening fungicides for use in fish culture: Evaluation of the agar plug transfer, cellophane transfer, and agar dilution methods

    USGS Publications Warehouse

    Bailey, Tom A.

    1983-01-01

    The reliability, reproducibility, and usefulness of three screening methods -- the cellophane transfer, the agar plug transfer, and the agar dilution -- to screen aquatic fungicides were evaluated. Achlya flagellata and Saprolegnia hypogyna were exposed to 1, 10, and 100 mg/L of malachite green to test each method. The cellophane transfer and agar plug transfer techniques had similar reliability and reproducibility in rating fungicidal activity, and were both superior to the agar dilution technique. The agar plug transfer and agar dilution techniques adequately projected in vivo activity of malachite green, but the cellophane transfer technique overestimated its activity. Overall, the agar plug transfer technique most accurately rated the activity of malachite green and was the easiest test to perform. It therefore appears to be the method of choice for testing aquatic fungicides.

  20. Improving agar electrospinnability with choline-based deep eutectic solvents.

    PubMed

    Sousa, Ana M M; Souza, Hiléia K S; Uknalis, Joseph; Liu, Shih-Chuan; Gonçalves, Maria P; Liu, LinShu

    2015-09-01

    Very recently our group has produced novel agar-based fibers by an electrospinning technique using water as solvent and polyvinyl alcohol (PVA) as co-blending polymer. Here, we tested the deep eutectic solvent (DES), (2-hydroxyethyl)trimethylammonium chloride/urea prepared at 1:2 molar ratio, as an alternative solvent medium for agar electrospinning. The electrospun materials were collected with an ethanol bath adapted to a previous electrospinning set-up. One weight percent agar-in-DES showed improved viscoelasticity and hence, spinnability, when compared to 1 wt% agar-in-water and pure agar nanofibers were successfully electrospun if working above the temperature of sol-gel transition (∼80 °C). By changing the solvent medium we decreased the PVA concentration (5 wt% starting solution) and successfully produced composite fibers with high agar contents (50/50 agar/PVA). Best composite fibers were formed with the 50/50 and 30/70 agar/PVA solutions. These fibers were mechanically resistant, showed tailorable surface roughness and diverse size distributions, with most of the diameters falling in the sub-micron range. Both nano and micro forms of agar fibers (used separately or combined) may have potential for the design of new and highly functional agar-based materials.

  1. Automatic Surface Inoculation of Agar Trays1

    PubMed Central

    Wilkins, Judd R.; Mills, Stacey M.; Boykin, Elizabeth H.

    1972-01-01

    A machine is described which automatically inoculates a plastic tray containing agar media with a culture by use of either a conventional inoculating loop or a cotton swab. Isolated colonies were obtained with an inoculating loop when a heavy inoculum (109 cells/ml) was used or with a cotton swab when a light inoculum (ca. 104 cells/ml) was used. Trays containing combinations of differential or selective media were used to (i) separate mixtures of gram-positive and gram-negative bacteria, (ii) facilitate isolation of organisms from clinical specimens, and (iii) compare colony growth characteristics of pure cultures. The design of the machine is simple, it is easy to use, and it relieves the operator from the manual task of streaking cultures. Images PMID:16349943

  2. Poisoning with brown fly agaric, Amanita regalis.

    PubMed

    Elonen, E; Tarssanen, L; Härkönen, M

    1979-01-01

    Three patients ate different amounts of a common northern mushroom, brown fly agaric, Amanita regalis. All of them believed they had eaten delicious parasol mushrooms, Macrolepiota procera. The symptoms of poisoning began 1--2 hours after ingestion of the mushrooms. All the patients had marked gastrointestinal symptoms: nausea and heavy vomiting. Two had central nervous system manifestations and cholinergic symptoms: hallucinations, confusion, or loss of consciousness as well as copious salivation, or sweating. All patients recovered within 4--24 hours without any damage to liver, kidneys or central nervous system. It seems that cooking the mushrooms does not completely neutralize the toxic agents of Amanita regalis. The analysis of fried mushrooms shows that it may be possible to identify mushrooms reliably from the remains of a meal.

  3. Improved medium for antimicrobial susceptibility testing of Haemophilus influenzae.

    PubMed Central

    Jorgensen, J H; Redding, J S; Maher, L A; Howell, A W

    1987-01-01

    The need for complex growth media has complicated routine susceptibility testing of Haemophilus influenzae because of antagonism of certain antimicrobial agents by the medium or because of difficulties in interpretation of growth endpoints. Haemophilus test medium (HTM) is a simple, transparent medium for broth- or agar-based tests with H. influenzae. HTM incorporates Mueller-Hinton medium with additions of 15 micrograms of hematin per ml, 15 micrograms of NAD per ml, and 5 mg of yeast extract per ml as growth-promoting additives. Agar or broth microdilution MICs of 10 antimicrobial agents for a collection of 179 H. influenzae isolates determined by using HTM compared favorably with MICs determined by the conventional agar or broth dilution methods recommended by the National Committee for Clinical Laboratory Standards. Disk diffusion tests performed with HTM allowed accurate categorization of susceptible and resistant strains and were easier to interpret than tests performed with Mueller-Hinton chocolate agar. A particular advantage of HTM was the reliability of broth- or agar-based test results with trimethoprim-sulfamethoxazole. The results of the study suggest modification of current National Committee for Clinical Laboratory Standards MIC-interpretive criteria for H. influenzae with amoxicillin-clavulanate, chloramphenicol, and trimethoprim-sulfamethoxazole. Error rate-bounded analysis of MICs and disk diffusion zone sizes also suggest modified zone-interpretive criteria for ampicillin, amoxicillin-clavulanate, chloramphenicol, and tetracycline with HTM or conventional media. Interpretive zone sizes are newly proposed for cefaclor and rifampin disk diffusion tests. PMID:3500965

  4. In vitro susceptibility testing of Paracoccidioides brasiliensis to sulfonamides.

    PubMed Central

    Restrepo, A; Arango, M D

    1980-01-01

    A total of 60 clinical isolates of Paracoccidioides brasiliensis were tested for susceptibility to sulfadiazine and sulfadimethoxyne by the agar dilution technique. A modification of the Mueller-Hinton medium was devised which gave good growth of the yeast form. The minimum inhibitory concentrations for only 51.6% of the isolates were in the range of the recommended blood serum concentration (50 micrograms/ml). For 6 to 8% of the isolates, the minimum inhibitory concentrations were above 200 micrograms of both sulfadiazine and sulfadimethoxyne per ml. A significant decreases in susceptibility was demonstrated for one isolate obtained from a patient relapsing during sulfonamide therapy. Images PMID:7416744

  5. In Vitro Response of Guinea Pig Peritoneal Macrophages to Legionella pneumophila

    DTIC Science & Technology

    1981-03-01

    causative agent of I strains. were cultured onl Mueller-Hinton agar supt)I- Legionnaires disease , have niot heeni well defined. niented with 2...In Vitro Responlse of Guinea Pig Peritoneal Macrophages to Legionella pneumophila It. A. KISIIIMi~O~’ .1. Ii.,W11ITE, F. G. SIREY, V. (U.1 Mc(GANN, R...obtained from the Centers for two washes of Hlanks balanced salt solution. Bacteria. Disease Control. Atlanta, Ga. The virulent P1hiladel- suspended in Earle

  6. Differences in activity profile of bacterial cultures studied by dynamic speckle patterns

    NASA Astrophysics Data System (ADS)

    Ramírez-Miquet, E. E.; Otero, I.; Rodríguez, D.; Darias, J. G.; Combarro, A. M.; Contreras, O. R.

    2013-02-01

    We outline the main differences in the activity profile of bacterial cultures studied by dynamic laser speckle (or biospeckle) patterns. The activity is detected in two sorts of culture mediums. The optical setup and the experimental procedure are presented. The experimentally obtained images are processed by the temporal difference method and a qualitative assessment is made with the time history of speckle patterns of the sample. The main differences are studied after changing the culture medium composition. We conclude that the EC medium is suitable to detect the E. coli bacterial presence in early hours and that Mueller Hinton agar delays some additional hours to make possible the assessment of bacteria in time.

  7. Selected elements in fly agaric Amanita muscaria.

    PubMed

    Falandysz, J; Kunito, T; Kubota, R; Lipka, K; Mazur, A; Falandysz, Justyna J; Tanabe, S

    2007-09-01

    Concentrations of Ag, Al, Ba, Ca, Cd, Co, Cu, Cr, Cs, Fe, Ga, Hg, K, Mg, Mn, Mo, Na, Pb, Rb, Se, Sb, Sr, V, Tl and Zn have been determined in the whole fruiting bodies, as well as separately in caps and stalks, of fly agaric collected from three geographically distant sites in northern part of Poland. The elements were determined using ICP-MS, ICP-OES, HG-AAS and CV-AAS, respectively. For elements such as Al, Ba, Cr, Fe, Ga, Mo, Mn, Pb, Sb, Sr, Tl, and V concentrations were similar in the caps and stalks, respectively, and for K, Zn, Ag, Ca, Cd, Cu, Hg, Mg, Rb and Se were greater in the caps, while for Co, Cs and Na in the stalks. For Ag, Al, Ba, Ca, Cd, Co, Cr, Cs, Fe, Ga, Hg, Mn, Mo, Pb, Rb, Sb, Sr, Tl and V concentration in the caps showed spatial variations (P<0.05), while for Cu, K, Mg, Na, Se and Zn was independent of the site. The elements such as K with median or mean in the caps between 37,000 and 43,000 microg/g.dm and Mg with 920 and 1,100 microg/g dm were most abundant. Next, within median values range from approximately 100 to 500 microg/g dm were such as Ca, Fe and Al, and in descending order they followed by Rb (100-400 microg/g dm); V, Na, Zn (50-200 microg/g dm); Cu, Mn (10-50 microg/g dm); Cd (10-20 microg/g dm); Se (5 microg/g dm); Ba (<1-3); Cr, Ag, Pb, Sr (<1-2 microg/g dm); Cs, Co, Hg (<1-1 microg/g dm); Ga (<0.5), Sb, Mo and Tl (<0.1 microg/g dm).

  8. Comparison of inhibitory mold agar to Sabouraud dextrose agar as a primary medium for isolation of fungi.

    PubMed

    Scognamiglio, Theresa; Zinchuk, Riva; Gumpeni, Pramod; Larone, Davise H

    2010-05-01

    Clinical specimens cultured on two selective fungal media, inhibitory mold agar (IMA) and Sabouraud dextrose agar (SDA), were compared with respect to recovery of fungi. Of the 840 fungal isolates recovered, 69.3% grew on both IMA and SDA; 24.9% grew only on IMA; and 5.8% grew only on SDA, showing that IMA is superior (P=0.003).

  9. Differentiation of Candida dubliniensis from Candida albicans on rosemary extract agar and oregano extract agar.

    PubMed

    de Loreto, Erico Silva; Pozzatti, Patrícia; Alves Scheid, Liliane; Santurio, Deise; Morais Santurio, Janio; Alves, Sydney Hartz

    2008-01-01

    Candida dubliniensis is a recently described pathogenic species which shares many phenotypic features with Candida albicans and therefore, may be misidentified in microbiological laboratories. Because molecular methods can be onerous and unfeasible in routine mycological laboratories with restricted budgets such as those in developing countries, phenotypic techniques have been encouraged in the development of differential media for the presumptive identification of these species. We examined the colony morphology and chlamydospore production of 30 C. dubliniensis isolates and 100 C. albicans isolates on two new proposed media: rosemary (Rosmarinus officinalis) extract agar (REA) and oregano (Origanum vulgare) extract agar (OEA). These substrates are traditionally used as spices and medicinal herbs. In both of these media, all C. dubliniensis isolates (100%) showed rough colonies with peripheral hyphal fringes and abundant chlamydospores after 24 to 48 hr of incubation at 25 degrees C. In contrast, under the same conditions, all isolates of C. albicans (100%) showed smooth colonies without hyphal fringes or chlamydospores. In conclusion, REA and OEA offer a simple, rapid, and inexpensive screening media for the differentiation of C. albicans and C. dubliniensis.

  10. Effect of water structure on gelation of agar in glycerol solutions and phase diagram of agar organogels.

    PubMed

    Boral, Shilpi; Bohidar, H B

    2012-06-21

    A comprehensive study of hydration of polyanionic agar molecules in its solution and gel phase in glycerol-water binary solvent is reported. Raman spectroscopy results predict differential water structure arrangement for glycerol-water binary solvent, 0.02% (w/v) agar in glycerol solution and 0.3% (w/v) agar organogel. The 3200 cm(-1) Raman band pertaining to ice-like structure of water was found to increase in gel phase alike in glycerol-water solvent while it decreased in agar solutions with increase in glycerol concentration. In contrast, the partially structured water corresponding to the component 3310 cm(-1) of Raman spectra increased in agar solution, and decreased in gel phase similar to glycerol-water solvent case. We have explained these observations based on a simple model where the available oxygen to hydrogen atom ratio in a given solvent-polymer system uniquely defines hydration in solution and gel phases. The gelation concentration was found to increase from 0.18 (for water) to 0.22% (w/v) (50% v/v glycerol solution) as the glycerol concentration was raised. Correspondingly, the gelation temperature, T(g), showed a decline from 40 to 20 °C, and the gel melting temperature, T(m), revealed a reduction from 81 to 65 °C in the same glycerol concentration regime. Two distinctive features are evident here: (i) presence of glycerol as a cosolvent does not favor the gelation of agar as compared to water and (ii) agar organogels are softer than their hydrogels. A unique 3D phase diagram for the agar organogel is proposed. Circular dichroism data confirmed that the agar molecules retained their biological activity in these solvents. Thus, it is shown that thermo-mechanical properties of these organogels could be systematically tuned and adapted as per application requirement.

  11. Use of agar/glycerol and agar/glycerol/water as a translucent brain simulant for ballistic testing.

    PubMed

    Falland-Cheung, Lisa; Waddell, J Neil; Lazarjan, Milad Soltanipour; Jermy, Mark C; Winter, Taylor; Tong, Darryl; Brunton, Paul A

    2017-01-01

    The suitability of agar/glycerol/water and agar/glycerol mixtures as brain simulants was investigated. Test specimens (n=15) (50x27×37mm) were fabricated for these different mixtures and conditioned to 12°C, 22°C, and 26°C prior to testing. For comparison, fresh deer brain specimens (n=20) were sourced and prepared to the same dimensions as the agar/glycerol(/water) mixtures and conditioned to 12°C and 37°C. High impact tests were carried out with a 0.22-caliber air rifle pellet and a high-speed camera was used to record the projectile as it passed through the specimens, allowing for energy loss and vertical displacement velocity calculation. Although the agar/glycerol/water mixture presented with similar vertical expansion and contraction of the specimens to the warm and cold deer brains, a two-fold decrease of the vertical expansion and contraction was noticed with the agar/glycerol specimens. Also considerably less extrusion of this mixture out of the exit and entry sides after specimen penetration was observed. Of the simulants tested, agar/glycerol/water was the most suitable brain simulant for ballistic testing and impact studies.

  12. Measuring antimicrobial susceptibility of Pseudomonas aeruginosa using Poloxamer 407 gel.

    PubMed

    Yamada, Hiroyuki; Koike, Naohito; Ehara, Tomoko; Matsumoto, Tetsuya

    2011-04-01

    Pseudomonas aeruginosa is a Gram-negative bacterium that causes various opportunistic infections. Chronic and intractable infections with P. aeruginosa are closely related to the high levels of resistance displayed by this organism to antimicrobial agents and its ability to form biofilms. Although the standard method for examining antimicrobial resistance involves susceptibility testing using Mueller-Hinton agar or broth, this method does not take into account the influence of biofilm formation on antimicrobial susceptibility. Poloxamer 407 is a hydrophilic, nonionic surfactant of the more general class of copolymers that can be used to culture bacteria with similar properties as cells in a biofilm environment. Therefore, the aim of this study was to compare the antimicrobial susceptibility of bacteria cultured in Poloxamer 407 gel to those grown on Mueller-Hinton agar using the Kirby-Bauer disk diffusion method with 24 strains of P. aeruginosa. Antimicrobial sensibility differed between the two mediums, with >60% of the strains displaying increased resistance to β-lactams when cultured on Poloxamer 407 gel. In addition, scanning electron microscopy revealed that typical biofilm formation and extracellular polymeric substance production was only observed with bacteria grown on Poloxamer 407 gel. Therefore, antimicrobial susceptibility test using Poloxamer 407 gel may provide more accurate information and allow the selection of suitable antimicrobial agents for treating patients infected with biofilm-forming pathogens.

  13. Hyperspectral imaging for detecting pathogens grown on agar plates

    NASA Astrophysics Data System (ADS)

    Yoon, Seung Chul; Lawrence, Kurt C.; Siragusa, Gregory R.; Line, John E.; Park, Bosoon; Windham, William R.

    2007-09-01

    This paper is concerned with the development of a hyperspectral imaging technique for detecting and identifying one of the most common foodborne pathogens, Campylobacter. Direct plating using agars is an effective tool for laboratory tests and analyses of microorganisms. The morphology (size, growth pattern, color, etc.) of colonies grown on agar plates has been widely used to tentatively differentiate organisms. However, it is sometimes difficult to differentiate target organisms like Campylobacters from other contaminants grown together on the same agar plates. A hyperspectral imaging system operating at the visible and near infrared (VNIR) spectral region from 400 nm to 900 nm was set up to measure spectral signatures of 17 different Campylobacter and non-Campylobacter subspecies. Protocols for culturing, imaging samples and for calibrating measured data were developed. The VNIR spectral library of all 17 organisms commonly encountered in poultry was established from calibrated hyperspectral images. A classification algorithm was developed to locate and identify Campylobacters, non-Campylobacter contaminants, and background agars with 99.29% accuracy. This research has a potential to be expanded to detect other pathogens grown on agar media.

  14. Fly agaric (Amanita muscaria) poisoning, case report and review.

    PubMed

    Satora, Leszek; Pach, Dorota; Butryn, Beata; Hydzik, Piotr; Balicka-Slusarczyk, Barbara

    2005-06-01

    Gathering and eating mushrooms and other plants containing psychoactive substances has become increasingly popular among young people experimenting with drugs. Dried fly agaric Amanita muscaria fruiting bodies were eaten by five young persons (18-21 years of age) at a party in order to evoke hallucinations. Visual and auditory hallucinations occurred in four of them, whereas a 18-year-old girl lost consciousness. The following morning, she went to the Clinic of Toxicology. Due to the fact that not all the active substances present in the fly agaric have been identified, and some of them have an effect after a period of latency, the patient was admitted for several days of observation during which check-up examinations were performed. After four days without any problems, she was discharged. The poisoning regressed with no organ complications. The remaining persons who had eaten the fly agaric were free from any complaints.

  15. Factors affecting the in vitro activity of cefoperazone against the Bacteroides fragilis group.

    PubMed Central

    Sutter, V L; Kwok, Y Y

    1981-01-01

    The in vitro activity of cefoperazone against 32 strains of bacteria of the Bacteroides fragilis group was determined on four media by using a variety of test parameters. Lower mean minimal inhibitory concentrations (MICs) were obtained on Mueller-Hinton blood agar and supplemented brain heart infusion agar than were obtained on brucella laked blood agar or Wilkins-Chalgren agar. Higher MICs were obtained with 6-h inocula than with 24-h inocula, and slightly higher MICs were obtained with tests read at 48 as compared with 24 h. Conducting tests in an anaerobic glove box had little effect. The greatest differences in mean MICs were seen with inoculum densities of 10(4) and 10(5) colony-forming units. PMID:6459765

  16. Lysine-iron agar in the detection of Arizona cultures.

    PubMed

    EDWARDS, P R; FIFE, M A

    1961-11-01

    A lysine-iron agar is described and recommended for the detection of Arizona strains which ferment lactose rapidly. Black colonies which appear on bismuth sulfite agar should be transferred to the medium. Salmonellae and Arizona cultures produce a distinctive reaction since they are the only recognized groups of enteric bacteria which regularly produce lysine decarboxylase rapidly and form large amounts of hydrogen sulfide. Use of the medium is particularly recommended in the examination of specimens from enteric infections in which shigellae and salmonellae are not detected.

  17. Method for Measuring Changes in Surface Tension on Agar

    PubMed Central

    Weisberg, David S.; Dworkin, Martin

    1983-01-01

    The surface tension of agar surfaces was determined by measuring the contact angles formed by drops of various hydrophobic liquids on the surface and then calculating the composite surface free energy function by solving a series of simultaneous equations derived from these data. This method was used to measure the change in the surface tension of agar produced by the addition of various concentrations of albumin. The resulting curve was typical of the effect of increasing concentrations of surfactants on surface tension. The method was compared with other methods of determining surface tension of solids, and it was concluded that the technique used here provided the most reliable results. PMID:16346273

  18. 21 CFR 866.4600 - Ouchterlony agar plate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Ouchterlony agar plate. 866.4600 Section 866.4600 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Immunology Laboratory Equipment and Reagents §...

  19. 21 CFR 866.4600 - Ouchterlony agar plate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Ouchterlony agar plate. 866.4600 Section 866.4600 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Immunology Laboratory Equipment and Reagents §...

  20. 21 CFR 866.4600 - Ouchterlony agar plate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Ouchterlony agar plate. 866.4600 Section 866.4600 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Immunology Laboratory Equipment and Reagents §...

  1. 21 CFR 866.4600 - Ouchterlony agar plate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Ouchterlony agar plate. 866.4600 Section 866.4600 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Immunology Laboratory Equipment and Reagents §...

  2. 21 CFR 866.4600 - Ouchterlony agar plate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Ouchterlony agar plate. 866.4600 Section 866.4600 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Immunology Laboratory Equipment and Reagents §...

  3. Improving agar electrospinnability with choline-based deep eutectic solvents

    Technology Transfer Automated Retrieval System (TEKTRAN)

    One percent agar (% wt) was dissolved in the deep eutectic solvent (DES), (2-hydroxyethyl) trimethylammonium chloride/urea at a 1:2 molar ratio, and successfully electrospun into nanofibers. An existing electrospinning set-up, operated at 50 deg C, was adapted for use with an ethanol bath to collect...

  4. An improved agar medium for growth of Geobacillus thermoglucosidarius strains.

    PubMed

    Javed, M; Baghaei-Yazdi, N; Qin, W; Amartey, S

    2017-01-01

    Geobacillus species have potential applications in many biotechnological processes. They are fastidious in their vitamin and amino acid requirements. A new semi-defined agar medium (SDM) was developed which gave consistently high viable cell counts of various G. thermoglucosidasius strains (5×10(8)-6×10(8)cfu/ml) under aerobic conditions at 70°C.

  5. [Modification of the lysine-iron agar (author's transl)].

    PubMed

    Wauters, G

    1975-12-01

    The addition of L-phenylalanine to the lysine-iron agar described by Edwards and Fife ]1] allows a more valuable screening of the Proteus group based on its deamination properties. Some minor modifications of the indicator and thiosulfate content lead to improve and earlier recording of the results.

  6. Thermal-induced ageing of agar solutions: impact on the structural and mechanical properties of agar gels

    NASA Astrophysics Data System (ADS)

    Mao, Bosi; Bentaleb, Ahmed; Louerat, Frédéric; Divoux, Thibaut; Snabre, Patrick

    Numerous hydrogels are prepared by cooling down to ambient temperature, aqueous polymer solutions brought to a boil. Although the incubation time of the polymer solution at such a high temperature could be used as a tuning parameter, its impact on the subsequent gelation has been poorly investigated. Here we study the effect of prolonged heating at 80°C on a 1.5% wt solution of agar, a natural polysaccharide. The incubation time is varied from a few hours up to five days. We show that the agar sol. continuously degrades as the result of both the hydrolysis and the intermolecular oxidation of the polymer chains. Furthermore, electronic microscopy and X-ray diffraction experiments reveal that gels formed from older agar sols display an increasingly coarser microstructure composed of micron-sized aggregated pieces of polysaccharides, in contrast with the fibrous-like structure of gels made from fresh sols. Along with structural changes prolonged incubation time leads to weaker gels of lower shear elastic modulus. Finally, macro-indentation experiments coupled to direct visualization show that increasing the incubation time of the agar sol. decreases the yield strain of the gel by a factor of three, while the rupture scenario turns continuously from brittle to ductile-like. Acknowledging funding from BioMérieux & CNRS.

  7. Development of a selective agar plate for the detection of Campylobacter spp. in fresh produce.

    PubMed

    Yoo, Jin-Hee; Choi, Na-Young; Bae, Young-Min; Lee, Jung-Su; Lee, Sun-Young

    2014-10-17

    This study was conducted to develop a selective medium for the detection of Campylobacter spp. in fresh produce. Campylobacter spp. (n=4), non-Campylobacter (showing positive results on Campylobacter selective agar) strains (n=49) isolated from fresh produce, indicator bacteria (n=13), and spoilage bacteria isolated from fresh produce (n=15) were plated on four Campylobacter selective media. Bolton agar and modified charcoal cefoperazone deoxycholate agar (mCCDA) exhibited higher sensitivity for Campylobacter spp. than did Preston agar and Hunt agar, although certain non-Campylobacter strains isolated from fresh produce by using a selective agar isolation method, were still able to grow on Bolton agar and mCCDA. To inhibit the growth of non-Campylobacter strains, Bolton agar and mCCDA were supplemented with 5 antibiotics (rifampicin, polymyxin B, sodium metabisulfite, sodium pyruvate, ferrous sulfate) and the growth of Campylobacter spp. (n=7) and non-Campylobacter strains (n=44) was evaluated. Although Bolton agar supplemented with rifampicin (BR agar) exhibited a higher selectivity for Campylobacter spp. than did mCCDA supplemented with antibiotics, certain non-Campylobacter strains were still able to grow on BR agar (18.8%). When BR agar with various concentrations of sulfamethoxazole-trimethoprim were tested with Campylobacter spp. (n=8) and non-Campylobacter (n=7), sulfamethoxazole-trimethoprim was inhibitory against 3 of 7 non-Campylobacter strains. Finally, we validated the use of BR agar containing 50mg/L sulfamethoxazole (BRS agar) or 0.5mg/L ciprofloxacin (BRCS agar) and other selective agars for the detection of Campylobacter spp. in chicken and fresh produce. All chicken samples were positive for Campylobacter spp. when tested on mCCDA, BR agar, and BRS agar. In fresh produce samples, BRS agar exhibited the highest selectivity for Campylobacter spp., demonstrating its suitability for the detection of Campylobacter spp. in fresh produce.

  8. Comparison of dosimetry gels prepared by agar and bovine gelatine

    NASA Astrophysics Data System (ADS)

    Sağsöz, M. E.; Korkut, Ö.; Alemdar, N.; Aktaş, S.; Çalı, E. B.; Kantarcı, M.

    2016-04-01

    Gel dosimeters are unique materials capable of showing three dimensional (3D) dose distributions of therapeutic or diagnostic exposures. Fricke gel dosimeters can be considered as chemical dosimeters that rely on a radiation-induced chemical reaction. Dose distribution of Fricke solutions containing Fe+2 ions determines the transformation of acidic, oxygen saturated Fe+2 ions to Fe+3 ions by the ionizing radiation in aqueous solutions. In this study we produced two different types of gel dosimeters using agar and bovine gelatin with similar fabrication methods. We compared the magnetic resonance (MR) T1 imaging responses of these two gel dosimeters to acquire a dose dependency of MR intensities. In conclusion agar gel dosimeters found to be produced easily and more consistent.

  9. A modified agar plate method for detection of Strongyloides stercoralis.

    PubMed

    Koga, K; Kasuya, S; Khamboonruang, C; Sukhavat, K; Ieda, M; Takatsuka, N; Kita, K; Ohtomo, H

    1991-10-01

    The agar plate method is a new technique with high detection rates for coprological diagnosis of human strongyloidiasis. This report details modifications of the technique and establishes a standardized procedure. We recommend that all plates should be carefully observed using a microscope because macroscopic observation can lead to false negative results. It is also advisable to pour formalin solution directly into microscopically positive dishes to collect worms by sedimentation. This procedure enables one to observe worms otherwise hidden. Sealing dishes with adhesive tape prevents larvae from crawling out of the dishes, eliminating any possibility in the reduction of detection rates, and greatly improves the safety conditions for the technician performing the procedure. We consider the agar plate method to be superior to the filter paper method in detecting Strongyloides, and we believe that it will eventually become the technique of choice.

  10. Phenotypic identification of Candida albicans by growth on chocolate agar.

    PubMed

    Sheth, Chirag C; Johnson, Elizabeth; Baker, Mark E; Haynes, Ken; Mühlschlegel, Fritz A

    2005-12-01

    In this study, we describe a simple method for the identification of Candida albicans in clinical samples. A total of 383 clinical isolates of Candida species were streaked onto chocolate agar and incubated for 48 h at 37 degrees C in the presence of an atmosphere of 6% CO2. All 208 of the C. albicans isolates tested, developed an easy to identify filamentous colony morphology. Of 175 other Candida species tested, 172 (98.3%) were distinguishable from C. albicans by their smooth colony morphology. Three isolates (1.7%) exhibited weak filamentation after prolonged incubation. Although not a routine medium in medical mycology a significant advantage of using chocolate agar lies in its use in clinical bacteriology laboratories for the isolation of fastidious bacteria. Implementation of the proposed method is applicable across a range of specimen types, thus allowing the direct identification of C. albicans in clinical samples. This simple method may allow a quicker entry into directed treatment.

  11. Agar-degrading bacteria isolated from Antarctic macroalgae.

    PubMed

    Alvarado, Roxana; Leiva, Sergio

    2017-03-10

    This study describes the taxonomic diversity of pigmented, agar-degrading bacteria isolated from the surface of macroalgae collected in King George Island, Antarctica. A total of 30 pigmented, agarolytic bacteria were isolated from the surface of the Antarctic macroalgae Adenocystis utricularis, Monostroma hariotii, Iridaea cordata, and Pantoneura plocamioides. Based on the 16S rRNA data, the agarolytic isolates were affiliated to the genera Algibacter, Arthrobacter, Brachybacterium, Cellulophaga, Citricoccus, Labedella, Microbacterium, Micrococcus, Salinibacterium, Sanguibacter, and Zobellia. Isolates phylogenetically related to Cellulophaga algicola showed the highest agarase activity in culture supernatants when tested at 4 and 37 °C. This is the first investigation of pigmented agar-degrading bacteria, members of microbial communities associated with Antarctic macroalgae, and the results suggest that they represent a potential source of cold-adapted agarases of possible biotechnological interest.

  12. Mupirocin-mucin agar for selective enumeration of Bifidobacterium bifidum.

    PubMed

    Pechar, Radko; Rada, Vojtech; Parafati, Lucia; Musilova, Sarka; Bunesova, Vera; Vlkova, Eva; Killer, Jiri; Mrazek, Jakub; Kmet, Vladimir; Svejstil, Roman

    2014-11-17

    Bifidobacterium bifidum is a bacterial species exclusively found in the human intestinal tract. This species is becoming increasingly popular as a probiotic organism added to lyophilized products. In this study, porcine mucin was used as the sole carbon source for the selective enumeration of B. bifidum in probiotic food additives. Thirty-six bifidobacterial strains were cultivated in broth with mucin. Only 13 strains of B. bifidum utilized the mucin to produce acids. B. bifidum was selectively enumerated in eight probiotic food supplements using agar (MM agar) containing mupirocin (100 mg/L) and mucin (20 g/L) as the sole carbon source. MM agar was fully selective if the B. bifidum species was presented together with Bifidobacterium animalis subsp. lactis, Bifidobacterium breve, and Bifidobacterium longum subsp. longum species and with lactic acid bacteria (lactobacilli, streptococci). Isolated strains of B. bifidum were identified using biochemical, PCR, MALDI-TOF procedures and 16S rRNA gene sequencing. The novel selective medium was also suitable for the isolation of B. bifidum strains from human fecal samples.

  13. Modeling development of inhibition zones in an agar diffusion bioassay.

    PubMed

    Chandrasekar, Vaishnavi; Knabel, Stephen J; Anantheswaran, Ramaswamy C

    2015-09-01

    A two-temperature agar diffusion bioassay is commonly used to quantify the concentration of nisin using Micrococcus luteus as the indicator microorganism. A finite element computational model based on Fick's second law of diffusion was used to predict the radius of the inhibition zone in this diffusion bioassay. The model developed was used to calculate nisin concentration profiles as a function of time and position within the agar. The minimum inhibitory concentration (MIC) of nisin against M. luteus was determined experimentally. The critical time (T c) for growth of M. luteus within the agar diffusion bioassay was experimentally determined using incubation studies with nisin. The radius of the inhibition zone was predicted from the computational model as the location where the predicted nisin concentration at T c was equal to MIC. The MIC was experimentally determined to be 0.156 μg mL(-1), and T c was determined to be 7 h. Good agreement (R (2) = 0.984) was obtained between model-predicted and experimentally determined inhibition zone radii.

  14. Electrospinning of agar/PVA aqueous solutions and its relation with rheological properties

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In this work, we report the successful fabrication of agar-based nanofibers by an electrospinning technique using water as the solvent media. A tubeless spinneret was attached inside the electrospinning chamber, operated at 50 deg C, to avoid agar gelation. Pure agar solution 1% (w/w) showed inadequ...

  15. Development of an eco-friendly agar extraction technique from the red seaweed Gracilaria lemaneiformis.

    PubMed

    Li, Haiyan; Yu, Xingju; Jin, Yan; Zhang, Wei; Liu, Yuanling

    2008-05-01

    The red seaweed, Gracilaria lemaneiformis growing as an aquaculture bioremediator along the coasts of Liaodong Peninsula, China, was investigated for the agar production. An eco-friendly method called agar photobleaching extraction process was developed for the benefit of workers' health and safety of the environment. The native agar (NA), alkali-modified agar (AA), chemical-bleached agar (CA) and photobleached agar (PA), which were extracted using different processes, were evaluated for their physical and chemical properties. The PA showed most desirable performances in terms of gel strength, gelling temperature, sulfate content and 3,6-anhydro-l-galactose content. Among the different processed agars, PA gel strength was 1913 g/cm2, the highest among the different processed agars, which increased 8.6% on the basis of the AA. Further we applied this new technique to extract agars from Gracilaria asiatica, and similar results were obtained with that of G. lemaneiformis. This indicates that the agar photobleaching extraction process is a feasible method for Gracilaria species and has a potential application. During the whole agar photobleaching extraction process the pigment content of G. lemaneiformis declined gradually and the TOC concentration in photobleaching solution increased along with the increase in the irradiation time. The mechanism of agar photobleaching could be elucidated by the photolysis theory.

  16. Actinomyces pyogenes: susceptibility of 103 clinical animal isolates to 22 antimicrobial agents.

    PubMed

    Guérin-Faublée, V; Flandrois, J P; Broye, E; Tupin, F; Richard, Y

    1993-01-01

    Actinomyces pyogenes induces suppurative diseases in ruminants and many other animal species. Most of the earlier antimicrobial susceptibility data has been obtained by disk diffusion techniques. Minimal inhibitory concentrations (MIC) of 22 antibiotics for 103 strains of A pyogenes of animal origin were determined by agar dilution test (Mueller-Hinton agar supplemented with 5% sheep blood). All the strains were susceptible to penicillin G, amoxicillin, methicillin, cephalothin, cefoperazone, pristinamycin, kanamycin, gentamicin, spectinomycin, chloramphenicol, vancomycin, novobiocin and rifampin. Fifty-nine percent were resistant to streptomycin, 67% to tetracycline, doxycycline and minocycline, 12% to erythromycin, spiramycin and lincomycin. Most of the strains resistant to macrolides and lincosamides exhibited a constitutive MLS(B)-like phenotype. In the cultural conditions used, it was not possible to determine accurate MIC of fucidic acid and pefloxacin.

  17. Nosocomial pneumonia caused by a glucose-metabolizing strain of Neisseria cinerea.

    PubMed

    Boyce, J M; Taylor, M R; Mitchell, E B; Knapp, J S

    1985-01-01

    We describe what appears to be the first reported case of nosocomial pneumonia caused by Neisseria cinerea. The isolate metabolized glucose when tested in BACTEC Neisseria Differentiation Kits (Johnston Laboratories), but did not produce detectable acid in cystine-Trypticase (BBL Microbiology Systems) agar medium or in modified oxidation-fermentation medium. Clinical laboratories that rely on the BACTEC method for differentiation of pathogenic neisseriae should be aware of the fact that N. cinerea may mimic N. gonorrhoeae when tested in BACTEC Neisseria Differentiation kits. The ability of N. cinerea to grow well on tryptic soy and Mueller-Hinton agars and its inability to grow on modified Thayer-Martin medium are characteristics which help to distinguish N. cinerea from N. gonorrhoeae.

  18. [A simple method for differentiating methicillin-resistant, penicillinase-positive and -negative staphylococci by agardiffusion test (author's transl)].

    PubMed

    Hirschl, A; Stanek, G; Rotter, M

    1980-01-01

    Coagulase-positive staphylococci (41 methicillin-resistant strains, 28 penicillinase-positive and 12 penicillinase-negative strains) were tested against most types of penicillines commercially available on the Austrian market using both broth-dilution test (incubated during 48 hours at 35 degrees C) and agardiffusion tests (incubated during 24 hours at 30, 35 and 37 degrees C) employing Mueller-Hinton-broth and -agar, respectively, in order to find out the most convenient way of detecting methicillin-resistant strains. Consecutively, the conclusions drawn from these experiments were verified for tests on Isosensitest-agar (Oxoid). It was demonstrated that methicillin-resistant strains could be detected easily with discs of methicillin and oxacillin at 30 degrees C (Fig. 1). At 35 degrees C this was nearly as easily possible for methicillin but oxacillin discs had to be used at amounts of 1 microgram instead of 5 microgram. Excepting penicillin G-discs with the other penicillines differing numbers of methicillin-resistant strains would have been missed at 37 degrees C (Fig. 1, 2). Only with discs containing 6 microgram penicillin G methicillin-resistant strains were unequivocally identifiable in the agardiffusion test at all 3 incubation-temperatures (Fig. 3), the largest inhibition zone diameter being 12 mm. Penicillinase-positive but methicillin-sensitive strains always produced larger inhibition zones up to 30 mm. From these strains again penicillinase-negative strains were equally well distinguishable by much larger inhibition zones. So, the conclusion was drawn that on Mueller-Hinton agar one disc loaded with 6 microgram of penicillin G allows proper distinction not only of methicillin-resistant and -sensitive but also of penicillinase-positive and -negative strains of staphylococci. On Isosensitest-agar this is true for an incubation-temperature of 35 but not 37 degrees C (Tab. 1).

  19. Comparison of Fecal Coliform Agar and Violet Red Bile Lactose Agar for Fecal Coliform Enumeration in Foods

    PubMed Central

    Leclercq, A.; Wanegue, C.; Baylac, P.

    2002-01-01

    A 24-h direct plating method for fecal coliform enumeration with a resuscitation step (preincubation for 2 h at 37 ± 1°C and transfer to 44 ± 1°C for 22 h) using fecal coliform agar (FCA) was compared with the 24-h standardized violet red bile lactose agar (VRBL) method. FCA and VRBL have equivalent specificities and sensitivities, except for lactose-positive non-fecal coliforms such as Hafnia alvei, which could form typical colonies on FCA and VRBL. Recovery of cold-stressed Escherichia coli in mashed potatoes on FCA was about 1 log unit lower than that with VRBL. When the FCA method was compared with standard VRBL for enumeration of fecal coliforms, based on counting carried out on 170 different food samples, results were not significantly different (P > 0.05). Based on 203 typical identified colonies selected as found on VRBL and FCA, the latter medium appears to allow the enumeration of more true fecal coliforms and has higher performance in certain ways (specificity, sensitivity, and negative and positive predictive values) than VRBL. Most colonies clearly identified on both media were E. coli and H. alvei, a non-fecal coliform. Therefore, the replacement of fecal coliform enumeration by E. coli enumeration to estimate food sanitary quality should be recommended. PMID:11916678

  20. Characterization of Leptospiral Chemoreceptors Using a Microscopic Agar Drop Assay.

    PubMed

    Affroze, Samia; Islam, Md Shafiqul; Takabe, Kyosuke; Kudo, Seishi; Nakamura, Shuichi

    2016-08-01

    Bacterial chemotaxis is induced by sensing chemical stimuli via chemoreceptors embedded in the cytoplasmic membrane, enabling the cells to migrate toward nutrients or away from toxins. The chemoreceptors of Escherichia coli and Salmonella spp. have been well studied and are functionally classified on the basis of detectable substrates. The spirochete Leptospira possesses more than ten chemoreceptors and shows attractive or repellent responses against some sugars, amino acids, and fatty acids. However, the roles of these chemoreceptors have not been investigated. In this study, we conducted a chemotaxis assay called microscopic agar drop assay in combination with competition experiments, determining whether two kinds of attractants are recognized by the same type of chemoreceptor in the saprophytic Leptospira strain, Leptospira biflexa. Analyzing the competition effect observed between several pairs of chemicals, we found that L. biflexa senses sugars via chemoreceptors different from those that sense amino acids and fatty acids.

  1. Surface migration of Staphylococcus xylosus on low-agar media.

    PubMed

    Dordet-Frisoni, Emilie; Gaillard-Martinie, Brigitte; Talon, Régine; Leroy, Sabine

    2008-05-01

    Staphylococcus xylosus is a commensal species commonly found on the skin of mammals, but also currently used as starter culture for meat fermentation. Most strains of this species colonize by forming a biofilm on abiotic surfaces. We show here that the majority of S. xylosus strains also exhibit extensive colony spreading on the surface of soft agar media. This phenomenon seemed to be independent of biofilm-forming ability. It occurred in different culture media and was dependent on temperature. Formation of a giant S. xylosus colony did not involve a biosurfactant. Microscopic observation showed that the front of the giant colony comprised a single layer of spacing cells with more packed cells in the median area. Supplementation of the soft media with DNase I increased S. xylosus colony spreading, indicating that extracellular DNA may be involved in limiting the phenomenon. The ability of S. xylosus to spread on semi-solid surfaces may constitute an advantage for surface colonization.

  2. Normal force controlled rheology applied to agar gelation

    NASA Astrophysics Data System (ADS)

    Mao, Bosi; Divoux, Thibaut; Snabre, Patrick

    2016-05-01

    A wide range of thermoreversible gels are prepared by cooling down to ambient temperature hot aqueous polymer solutions. During the sol-gel transition, such materials may experience a volume contraction which is traditionally overlooked as rheological measurements are usually performed in geometries of constant volume. In this article, we revisit the formation of 1.5\\% wt. agar gels through a series of benchmark rheological experiments performed with a plate-plate geometry. We demonstrate on that particular gel of polysaccharides that the contraction associated with the sol/gel transition cannot be neglected. Indeed, imposing a constant gap width during the gelation results in the strain hardening of the sample, as evidenced by the large negative normal force that develops. Such hardening leads to the slow drift in time of the gel elastic modulus $G'$ towards ever larger values, and thus to an erroneous estimate of $G'$. As an alternative, we show that imposing a constant normal force equals to zero during the gelation, instead of a constant gap width, suppresses the hardening as the decrease of the gap compensates for the sample contraction. Using normal force controlled rheology, we then investigate the impact of thermal history on 1.5\\% wt. agar gels. We show that neither the value of the cooling rate, nor the introduction of a constant temperature stage during the cooling process influence the gel elastic properties. Instead, $G'$ only depends on the terminal temperature reached at the end of the cooling ramp, as confirmed by direct imaging of the gel microstructure by cryoelectron microscopy. The present work offers an extensive review of the technical difficulties associated with the rheology of hydrogels and paves the way for a systematic use of normal force controlled rheology to monitor non-isochoric processes.

  3. Comparison of spiral gradient and conventional agar dilution for susceptibility testing of anaerobic bacteria.

    PubMed Central

    Wexler, H M; Molitoris, E; Jashnian, F; Finegold, S M

    1991-01-01

    Antimicrobial susceptibility tests were performed on brucella laked blood agar with 340 isolates and 14 antimicrobial agents by the standard agar dilution technique and the spiral gradient technique in which antibiotic concentrations were established by diffusion from the agar surface. For comparison, spiral gradient MICs were determined by calculating antimicrobial concentrations at growth endpoints and rounding up to the next twofold incremental concentration. The cumulative percentage of strains susceptible at the breakpoint determined from spiral gradient data was within 10%, generally, of the percentage of strains susceptible at the breakpoint determined from agar dilution data. The overall agreement between the two techniques (within one doubling dilution) was 90.6%. The spiral gradient agar dilution technique is a reasonable alternative to the conventional agar dilution technique for susceptibility testing of anaerobic bacteria. Images PMID:1929262

  4. Residual Agar Determination in Bacterial Spores by Electrospray Ionization Mass Spectrometry

    SciTech Connect

    Wahl, Karen L.; Colburn, Heather A.; Wunschel, David S.; Petersen, Catherine E.; Jarman, Kristin H.; Valentine, Nancy B.

    2010-02-15

    Presented here is an analytical method to detect residual agar from a bacterial spore sample as an indication of culturing on an agar plate. This method is based on the resolubilization of agar polysaccharide from a bacterial spore sample, enzymatic digestion, followed by electrospray ionization tandem mass spectrometry (ESI-MSn) analysis for detection of a specific agar fragment ion. A range of Bacillus species and strains were selected to demonstrate the effectiveness of this approach. The characteristic agar fragment ion was detected in the spores grown on agar that were washed from 1 to 5 times, irradiated or non-irradiated and not in the spores grown in broth. A sample containing approximately 108 spores is currently needed for confident detection of residual agar from culture on agar plates in the presence of bacterial spores with a limit of detection of approximately 1 ppm agar spiked into a broth-grown spore sample. The results of a proficiency test with 42 blinded samples are presented demonstrating the utility of this method with no false positives and only 3 false negatives for samples that were below the detection level of the method as documented.

  5. Biochemical differentiation of the Enterobacteriaceae with the aid of lysine-iron-agar.

    PubMed

    Johnson, J G; Kunz, L J; Barron, W; Ewing, W H

    1966-03-01

    A procedure is described for identifying members of the family Enterobacteriaceae isolated from clinical specimens. The methods are based on primary differentiation of the various groups of bacteria by the use of Kligler Iron Agar and lysine-iron-agar. For identification of Salmonella, Shigella, and Arizona group organisms from stools, Triple Sugar Iron Agar and lysine-iron-agar are employed. The usefulness of this schema for diagnostic bacteriology laboratories is discussed. It is not intended to replace methods used in reference or research laboratories.

  6. Comparison of isolation of Haemophilus vaginalis (Corynebacterium vaginale) from peptone-starch-dextrose agar and Columbia colistin-nalidoxic acid agar.

    PubMed Central

    Golberg, R L; Washington JA, I I

    1976-01-01

    A total of 447 cervical or vaginal specimens were inoculated in parallel onto peptone-starch-dextrose (PSD) and Columbia colistin (10 mg/ml)-nalidixic acid (15 mug/ml) (CNA) agar and were incubated for 48 h at 35 degrees C in an atmosphere with 2 to 10% CO2. One hundred (22.4%) of the cultures were positive for Haemophilus vaginalis. Forty-eight of the isolates were recovered from both PSD and Columbia CNA agar, five from PSD only, and 47 from Columbia CNA agar only (P less than 0.001). On Columbia CNA agar, 76 of the isolates were detected after 24 h of incubation, and the remainder were detected within 4 days of incubation. PMID:1085777

  7. NAS agar is more suitable than McKay agar for primary culture of Streptococcus milleri group (SMG) fastidious bacteria, S. intermedius in particular.

    PubMed

    Raclavsky, Vladislav; Novotny, Radko; Stary, Lubomir; Navratilova, Lucie; Zatloukal, Jaromir; Jakubec, Petr; Zapalka, Martin; Kopriva, Frantisek; Kolek, Vitezslav

    2017-01-01

    Streptococcus milleri group (SMG) is a group of three streptococcal species (S. anginosus, intermedius and constellatus) that act as opportunist pathogens, among others in cystic fibrosis. Due to their fastidious character, they are both difficult to cultivate and to differentiate from less pathogenic streptococcal species, therefore being most probably underdiagnosed. Semi-selective McKay agar and NAS agar were developed to facilitate SMG recovery from clinical samples; however, direct comparison of recovery rates has not been published yet. We tested the performance of both media on 123 patient samples and demonstrated general superiority of NAS agar for SMG recovery during primary cultivation convincingly. This observation was also confirmed by quantitative drop tests during subculture. Despite the undisputed overall superiority of NAS agar over McKay agar, a smaller fraction of strains grew better on McKay agar. Inter-strain differences were the most probable explanation. Therefore, when economic conditions are not limiting and maximum recovery rate is desirable, both plates are advised to be used in parallel for primary cultivation of clinical samples.

  8. Evaluation of fluorogenic TSC agar for recovering Clostridium perfringens in groundwater samples.

    PubMed

    Araujo, M; Sueiro, R A; Gómez, M J; Garrido, M J

    2001-01-01

    Clostridium perfringens is widely recognised as a reliable water pollution indicator. Since several media can be employed for the membrane filtration enumeration of this microorganism, the main aim of this work was to investigate the ability of fluorocult-supplemented TSC-agar (Merck) for recovering Cl. perfringens from public springs used for direct human consumption. Cl. perfringens recovery was also performed on mCP agar (Cultimed) according to Directive 98/83 as well as on TSC-Agar (Merck), TSN-Agar (Merck) and SPS-Agar (BBL) media. Variance analysis of data obtained showed no statistically significant differences in the counts obtained among all media employed in this work. However, the Cl. perfringens recovery efficiencies with TSC and fluorogenic TSC agars were significantly greater (P = < 0.05) than the corresponding values of mCP and TSN media. On the other hand, the identification of typical and atypical colonies isolated from all media demonstrated that fluorogenic TSC agar was the most specific medium for Cl. perfringens recovery in groundwater samples (85.3% of typical colonies and 82.8% of atypical colonies confirmed). In summary, the membrane filtration technique with fluorogenic TSC agar showed the best performance characteristics of all the media tested as judged by their recovery efficiency and specificity in these water samples.

  9. Electrospinning of agar/PVA aqueous solutions and its relation with rheological properties.

    PubMed

    Sousa, Ana M M; Souza, Hiléia K S; Uknalis, Joseph; Liu, Shih-Chuan; Gonçalves, Maria P; Liu, LinShu

    2015-01-22

    In this work, we report the successful fabrication of agar-based nanofibers by electrospinning technique, using water as solvent media. A tubeless spinneret was attached inside the electrospinning chamber, operating at 50°C, to avoid agar gelation. Agar pure solution (1 wt%) showed inadequate spinnability regardless of the used electrospinning conditions. The addition of a co-blending polymer such as PVA (10 wt% starting solution) improved the solutions viscoelasticity and hence, the solutions spinnability. Agar/PVA solutions were prepared with different mass ratios (100/0, 50/50, 40/60, 30/70, 20/80 and 0/100) and electrospun at various sets of electrospinning conditions. Best nanofibers were obtained with 30/70 and 20/80 agar/PVA blends while samples with higher agar contents (50/50 and 40/60 agar/PVA) were harder to process and led to discontinuous fibrous mats. This first set of encouraging results can open a new window of opportunities for agar-based biomaterials in the form of nanofibers.

  10. Characteristics of thermoplastic sugar palm Starch/Agar blend: Thermal, tensile, and physical properties.

    PubMed

    Jumaidin, R; Sapuan, S M; Jawaid, M; Ishak, M R; Sahari, J

    2016-08-01

    The aim of this work is to study the behavior of biodegradable sugar palm starch (SPS) based thermoplastic containing agar in the range of 10-40wt%. The thermoplastics were melt-mixed and then hot pressed at 140°C for 10min. SEM investigation showed good miscibility between SPS and agar. FT-IR analysis confirmed that SPS and agar were compatible and inter-molecular hydrogen bonds existed between them. Incorporation of agar increased the thermoplastic starch tensile properties (Young's modulus and tensile strength). The thermal stability and moisture uptake increased with increasing agar content. The present work shows that starch-based thermoplastics with 30wt% agar content have the highest tensile strength. Higher content of agar (40wt%) resulted to more rough cleavage fracture and slight decrease in the tensile strength. In conclusion, the addition of agar improved the thermal and tensile properties of thermoplastic SPS which widened the potential application of this eco-friendly material. The most promising applications for this eco-friendly material are short-life products such as packaging, container, tray, etc.

  11. Synthesis, Characterization and Antimicrobial Activity of d8-10 Metal Complexes of some 2-Substituted-1H-Benzimidazoles

    PubMed Central

    Tavman, Aydin; Ötük, Gülten

    1999-01-01

    The metal complexes of nine 2-substituted-1H-benzimidazoles (I-IX) with Ni(II), Pd(II), Cu(II), Ag(I), Zn(II) salts were synthesized. The compounds were characterized by melting point, analytical data, IR spectroscopy and magnetic susceptibility. The antimicrobial activity of the compounds was determined by the disk diffusion method in Mueller-Hinton Agar on Staphylococcus aureus ATCC 6538, Staphylococcus epidermidis ATCC 12228, Escherichia coli ATCC 8739, Klebsiella pneumoniae ATCC 4352, Pseudomonas aeruginosa ATCC 1539, Salmonella typhi, Shigella flexneri, Proteus mirabilis, Candida albicans ATCC 10231. Cu(II)and Ag(I)complexes of II, III and IV showed considerable activity against S. aureus, S. epidermidis, Ps. aeruginosa, S. typhi, Sh. flexneri and C. albicans microorganisms, the ligands themselves having no effect. PMID:18472907

  12. Influence of Culture Media on Microbial Fingerprints Using Raman Spectroscopy

    PubMed Central

    Mlynáriková, Katarína; Samek, Ota; Bernatová, Silvie; Růžička, Filip; Ježek, Jan; Hároniková, Andrea; Šiler, Martin; Zemánek, Pavel; Holá, Veronika

    2015-01-01

    Raman spectroscopy has a broad range of applications across numerous scientific fields, including microbiology. Our work here monitors the influence of culture media on the Raman spectra of clinically important microorganisms (Escherichia coli, Staphylococcus aureus, Staphylococcus epidermidis and Candida albicans). Choosing an adequate medium may enhance the reproducibility of the method as well as simplifying the data processing and the evaluation. We tested four different media per organism depending on the nutritional requirements and clinical usage directly on a Petri dish. Some of the media have a significant influence on the microbial fingerprint (Roosvelt-Park Institute Medium, CHROMagar) and should not be used for the acquisition of Raman spectra. It was found that the most suitable medium for microbiological experiments regarding these organisms was Mueller-Hinton agar. PMID:26610516

  13. Antimicrobial activity and phytochemical analysis of crude extracts and essential oils from medicinal plants.

    PubMed

    Silva, N C C; Barbosa, L; Seito, L N; Fernandes, A

    2012-01-01

    We aimed to establish a phytochemical analysis of the crude extracts and performed GC-MS of the essential oils (EOs) of Eugenia uniflora L. (Myrtaceae) and Asteraceae species Baccharis dracunculifolia DC, Matricaria chamomilla L. and Vernonia polyanthes Less, as well as determining their antimicrobial activity. Establishment of the minimal inhibitory concentrations of the crude extracts and EOs against 16 Staphylococcus aureus and 16 Escherichia coli strains from human specimens was carried out using the dilution method in Mueller-Hinton agar. Some phenolic compounds with antimicrobial properties were established, and all EOs had a higher antimicrobial activity than the extracts. Matricaria chamomilla extract and E. uniflora EO were efficient against S. aureus strains, while E. uniflora and V. polyanthes extracts and V. polyanthes EO showed the best antimicrobial activity against E. coli strains. Staphylococcus aureus strains were more susceptible to the tested plant products than E. coli, but all natural products promoted antimicrobial growth inhibition.

  14. Green Synthesis and Characterization of Silver Nanoparticles for Antimicrobial Activity Against Burn Wounds Contaminating Bacteria

    NASA Astrophysics Data System (ADS)

    Rout, Anandini; Jena, Padan K.; Sahoo, Debasish; Parida, Umesh K.; Bindhani, Birendra K.

    2014-04-01

    Silver nanoparticles (AgNPs) were prepared from the plant extract of N. arbor-tristis under atmospheric conditions through green synthesis and characterized by various physicochemical techniques like UV-Visible spectroscopy, IR Spectra, energy dispersive X-ray spectrometry (EDS), X-ray diffraction and transmission electron microscopy (TEM) and the results confirmed the synthesis of homogeneous and stable AgNPs by the plant extracts. The antimicrobial activity of AgNPs was investigated against most common bacteria found in burn wound Staphylococcus epidermidis and Pseudomonas aeruginosa. In these tests, Mueller Hinton agar plates were used with AgNPs of various concentrations, supplemented in liquid systems. P. aeruginosa was inhibited at the low concentration of AgNPs, whereas the growth-inhibitory effect on S. epidermidis was mild. These results suggest that AgNPs can be used as effective growth inhibitors of various microorganisms, making them applicable to diverse medical devices and antimicrobial control systems.

  15. In vitro susceptibility of Mycobacterium fortuitum to non-antituberculous antibacterial agents.

    PubMed

    Casal, M J; Rodriguez, F C

    1983-01-01

    A study was made of the in vitro susceptibility of 37 strains of Mycobacterium fortuitum to 14 antimicrobial agents using disc diffusion techniques on Mueller-Hinton agar plates. Nitro-5-hydroxy-8-quinoleine and pipemidic acid inhibited all strains, while furantoin, mandelamine, metronidazole, nalidixic acid, oxolinic acid and trimethoprim proved to be inactive. In addition, various sulphonamides inhibited 59% of the strains tested. Sulphadiazine inhibited 54.1%, sulphafurazole 64.9%, sulphamethizole 64.9%, sulphametoxypyridazine 62.2% and sulphisoxazole 59.5%. Trimethoprim-sulphamethoxazole was effective against 48.6% of the strains due to its sulph component. The sensitivity to sulphonamides varied in accordance with the origin of the strains, those of human origin being generally much more susceptible than those of non-human origin.

  16. Sensitivity to antibiotics of Arcanobacterium pyogenes and Escherichia coli from the uteri of cows with metritis/endometritis.

    PubMed

    Malinowski, Edward; Lassa, Henryka; Markiewicz, Hanna; Kaptur, Maciej; Nadolny, Marek; Niewitecki, Wiesław; Ziętara, Jacek

    2011-02-01

    The aim of the study was to determine the in vitro sensitivity of 161 Arcanobacterium pyogenes strains and 99 Escherichia coli strains isolated from the uteri of 312 cows with metritis/endometritis. Animals with pathological discharges were clinically diagnosed per rectum and per vaginum, and then swabs from the lumen of the uterus were aseptically collected. Bacteriological examination of swabs was according to commonly accepted procedures with the additional use of API tests. Sensitivity to antibiotics was tested by the disk diffusion method and performed in Mueller-Hinton agar. Arc. pyogenes strains were the most sensitive to amoxicillin/clavulanic acid (Amc) (97.3%), bacitracin (96.7%), ceftiofur (95.8%) and cephapirin (77.5%). E. coli strains were the most sensitive to norfloxacin (98.1%), marbofloxacin (95.8%), gentamycin (88%), Amc (80.7%) and ceftiofur (73.1%). Arc. pyogenes and E. coli were most resistant to oxytetracycline (63.7% and 31%, respectively).

  17. Plaque assay for virulent Legionella pneumophila.

    PubMed Central

    Fernandez, R C; Lee, S H; Haldane, D; Sumarah, R; Rozee, K R

    1989-01-01

    Methods of assessing virulence of Legionella pneumophila, the etiologic agent of Legionnaires disease, include the infection of guinea pigs, fertile chicken eggs, and mammalian and protozoan cell cultures. Guinea pig assays, in particular, are expensive, laborious, or unsuitable for routine screening of Legionella isolates. We have developed a virulence assay that requires the enumeration of viruslike plaques which are the result of virulent L. pneumophila infecting mouse L929 cells. Each plaque is the consequence of the initial infection of an L cell with a single bacterium. A nonvirulent mutant derived from the serial passage of virulent L. pneumophila on Mueller-Hinton agar fails to survive within L cells and consequently fails to produce plaques. Images PMID:2674192

  18. Functions and activities of the Area Committee on Microbiology of the National Committee for Clinical Laboratory Standards.

    PubMed Central

    Washington, J A

    1991-01-01

    The Area Committee on Microbiology of the National Committee for Clinical Laboratory Standards has responsibility for the development of guidelines and standards in the field of clinical microbiology. Through the consensus process, representatives from government, industry, and professional societies have developed standards on antibacterial susceptibility testing (M2, M7, and M11), antimycobacterial susceptibility testing (M24), quality assurance on commercially prepared microbiological culture media (M22), evaluation of production lots of dehydrated Mueller-Hinton agar (M6), and preparation and testing of fetal bovine serum for use as cell culture growth supplement (M25) and guidelines on bactericidal tests (M26), protection of laboratory workers from infections transmitted by blood, body fluids, and tissue (M29), blood film examination for parasites (M15), and development of in vitro susceptibility testing criteria and quality control parameters (M23). PMID:2070343

  19. Influence of Culture Media on Microbial Fingerprints Using Raman Spectroscopy.

    PubMed

    Mlynáriková, Katarína; Samek, Ota; Bernatová, Silvie; Růžička, Filip; Ježek, Jan; Hároniková, Andrea; Šiler, Martin; Zemánek, Pavel; Holá, Veronika

    2015-11-24

    Raman spectroscopy has a broad range of applications across numerous scientific fields, including microbiology. Our work here monitors the influence of culture media on the Raman spectra of clinically important microorganisms (Escherichia coli, Staphylococcus aureus, Staphylococcus epidermidis and Candida albicans). Choosing an adequate medium may enhance the reproducibility of the method as well as simplifying the data processing and the evaluation. We tested four different media per organism depending on the nutritional requirements and clinical usage directly on a Petri dish. Some of the media have a significant influence on the microbial fingerprint (Roosvelt-Park Institute Medium, CHROMagar) and should not be used for the acquisition of Raman spectra. It was found that the most suitable medium for microbiological experiments regarding these organisms was Mueller-Hinton agar.

  20. Antimicrobial susceptibility testing of aquatic bacteria: quality control disk diffusion ranges for Escherichia coli ATCC 25922 and Aeromonas salmonicida subsp. salmonicida ATCC 33658 at 22 and 28 degrees C.

    PubMed

    Miller, R A; Walker, R D; Baya, A; Clemens, K; Coles, M; Hawke, J P; Henricson, B E; Hsu, H M; Mathers, J J; Oaks, J L; Papapetropoulou, M; Reimschuessel, R

    2003-09-01

    Quality control (QC) ranges for disk diffusion susceptibility testing of aquatic bacterial isolates were proposed as a result of a multilaboratory study conducted according to procedures established by the National Committee for Clinical Laboratory Standards (NCCLS). Ranges were proposed for Escherichia coli ATCC 25922 and Aeromonas salmonicida subsp. salmonicida ATCC 33658 at 22 and 28 degrees C for nine different antimicrobial agents (ampicillin, enrofloxacin, erythromycin, florfenicol, gentamicin, oxolinic acid, oxytetracycline, ormetoprim-sulfadimethoxine, and trimethoprim-sulfamethoxazole). All tests were conducted on standard Mueller-Hinton agar. With >/=95% of all data points fitting within the proposed QC ranges, the results from this study comply with NCCLS guidelines and have been accepted by the NCCLS Subcommittee for Veterinary Antimicrobial Susceptibility Testing. These QC guidelines will permit greater accuracy in interpreting results and, for the first time, the ability to reliably compare susceptibility test data between aquatic animal disease diagnostic laboratories.

  1. Antimicrobial Susceptibility Testing of Aquatic Bacteria: Quality Control Disk Diffusion Ranges for Escherichia coli ATCC 25922 and Aeromonas salmonicida subsp. salmonicida ATCC 33658 at 22 and 28°C

    PubMed Central

    Miller, R. A.; Walker, R. D.; Baya, A.; Clemens, K.; Coles, M.; Hawke, J. P.; Henricson, B. E.; Hsu, H. M.; Mathers, J. J.; Oaks, J. L.; Papapetropoulou, M.; Reimschuessel, R.

    2003-01-01

    Quality control (QC) ranges for disk diffusion susceptibility testing of aquatic bacterial isolates were proposed as a result of a multilaboratory study conducted according to procedures established by the National Committee for Clinical Laboratory Standards (NCCLS). Ranges were proposed for Escherichia coli ATCC 25922 and Aeromonas salmonicida subsp. salmonicida ATCC 33658 at 22 and 28°C for nine different antimicrobial agents (ampicillin, enrofloxacin, erythromycin, florfenicol, gentamicin, oxolinic acid, oxytetracycline, ormetoprim-sulfadimethoxine, and trimethoprim-sulfamethoxazole). All tests were conducted on standard Mueller-Hinton agar. With ≥95% of all data points fitting within the proposed QC ranges, the results from this study comply with NCCLS guidelines and have been accepted by the NCCLS Subcommittee for Veterinary Antimicrobial Susceptibility Testing. These QC guidelines will permit greater accuracy in interpreting results and, for the first time, the ability to reliably compare susceptibility test data between aquatic animal disease diagnostic laboratories. PMID:12958263

  2. Difficulties in differentiating Neisseria cinerea from Neisseria gonorrhoeae in rapid systems used for identifying pathogenic Neisseria species.

    PubMed

    Boyce, J M; Mitchell, E B

    1985-11-01

    Neisseria cinerea and Neisseria gonorrhoeae may occur at the same body sites and may have similar colony morphologies. Ideally, systems used for rapid identification of N. gonorrhoeae should be able to differentiate N. cinerea from gonococci. We tested seven N. cinerea strains using the Gonochek II (Du Pont Diagnostics), Minitek (BBL Microbiology Systems), RapID-NH (Innovative Diagnostics, Inc.), RIM-N (American Microscan), and Phadebact (Pharmacia Diagnostics) systems. We found that the reactions produced by N. cinerea in Gonochek II, Minitek, and RapID-NH kits could be confused with the results produced by some strains of N. gonorrhoeae. The susceptibility of N. cinerea to colistin, its ability to grow on tryptic soy or Mueller-Hinton agar, and its inability to grow on modified Thayer-Martin medium help differentiate it from gonococci.

  3. Adsorptive removal of methylene blue by agar: effects of NaCl and ethanol

    PubMed Central

    2012-01-01

    Adsorption of methylene blue (MB) on agar was investigated as a function of temperature (308-328 K), different concentrations of NaCl and HCl and various weight percentages of binary mixtures of ethanol with water. It was observed that the maximum experimental adsorption capacity, qm, exp, in water is up to 50 mg g-1 and decreases with increase in weight percentage of ethanol and NaCl and HCl concentration compared to that of water. Analysis of data using ARIAN model showed that MB adsorbs as monomer and dimer on the surface of agar. Binding constants of MB to agar were calculated using the Temkin isotherm. The process is exothermic in water and other solutions. The mean adsorption energy (E) value indicated binding of MB to agar is chemical adsorption. Kinetics of this interaction obeys from the pseudo-second-order model and diffusion of the MB molecules into the agar is the main rate-controlling step. PMID:22339759

  4. [Evaluation of a new medium, eggplant (Solanum melongena) agar as a screening medium for Cryptococcus neoformans in environmental samples].

    PubMed

    Sengul, Mustafa; Ergin, Cağrı; Kartal, Tuğba

    2014-04-01

    Cryptococcus neofomans is an encapsulated yeast-like fungus that causes life-threatening infections, especially in immunosuppresive patients. C.neoformans infection is believed to be acquired via inhalation of aerosolized particles from the environment. Avian guano, decaying tree hollows and soil are the related known environmental niches. Brown pigmented yeast growth from the precursors in growth media is an important step for the identification and isolation of C.neoformans. Seeds of plants in nature are preferred owing to easy accessibility and low costs for the preparation of such media. Guizotia abysinicca (Niger seed) as Staib agar, Helianthus annus (Sunflower) as Pal's medium, Brassica nigra (Mustard) agar, tobacco agar, Mucuna pruriens (Velvet bean) seed agar, Perilla frutescens (Beefsteak plant) seed agar, Rubus fruticosus (Blackberry) agar and ground red hot pepper agar are pigment-based selective media for the differentiation of C.neoformans. The aim of this study was to observe the pigment production of C.neoformans in a new medium based on eggplant (Solanum melongena) and also to compare its performance with the simplified Staib, Pal's and tobacco agar for isolation from the environment. Three different eggplant-based medium (S.melongena Melanzaza viserba, S.melongena Pinstripe F1 and S.ovigerum Ivory F1) were included in the study. Pigment-forming eggplant medium, simplified Staib agar, Pal's agar and tobacco agar were used for the cultivation of the environmental swabbed samples from 19 Eucalyptus camaldulensis trunk hollows in continuous colonization region. While pigment formation were observed with S.melongena Melanzaza viserba and S.melongena Pinstripe F1 containing media, S.ovigerum Ivory F1 medium was found to be non-reactive. In colonization area (Gökova-Akyaka, Turkey), 11 (57.9%) out of 19 E.camaldulensis samples were positive with simplified Staib agar, Pal's agar and eggplant agar while 10 (52.6%) of them are positive with tobacco agar. C

  5. A novel agar formulation for isolation and direct enumeration of Vibrio vulnificus from oyster tissue.

    PubMed

    Griffitt, Kimberly J; Grimes, D Jay

    2013-08-01

    A new selective and differential medium, Vibrio vulnificus X-Gal (VVX), was developed for direct enumeration of V. vulnificus (Vv) from oyster samples. This agar utilizes cellobiose and lactose as carbon sources, and the antibiotics colistin and polymyxin B as selective agents. Hydrolysis of 5-bromo-4-chloro-3-indolyl- beta-d-galactopyranoside (x-gal), used in the agar as a lactose analog, produces an insoluble blue dye that makes lactose positive colonies easily distinguishable from any non-lactose fermenting bacteria. Various bacterial species were spot plated onto thiosulfate-citrate-bile salts-sucrose agar (TCBS), and CHROMagar Vibrio, two vibrio-specific selective agars, non-selective agar, and VVX to compare selectivity of VVX to other widely used media. A V. vulnificus pure culture was serially diluted on VVX and non-selective agar to determine the VVX percent recovery. Water and oyster samples were spread plated on VVX agar and allowed to incubate for 16-18 h at 33 °C. Blue and white colonies from VVX agar were picked and screened by end point PCR for the Vv hemolysin vvhA. VVX agar showed a significant improvement over TCBS and CHROMagar at preventing non-target growth. There was an 87.5% recovery compared to non-selective plating and a 98% positivity rate of blue colonies picked from oyster tissue plating. The findings suggest that this new agar is a fast, distinctive, and accurate method for enumeration of V. vulnificus from the environment.

  6. Detection of methicillin/oxacillin resistance and typing in aminoglycoside-susceptible methicillin-resistant and kanamycin-tobramycin-resistant methicillin-susceptible Staphylococcus aureus.

    PubMed

    Hamdad, F; Donda, F; Lefebvre, J F; Laurans, G; Biendo, M; Thomas, D; Canarelli, B; Rousseau, F; Eb, F

    2006-01-01

    Eighty-five atypical isolates of Staphylococcus aureus divided into 73 aminoglycoside-susceptible methicillinresistant (AS-MRSA) and 12 kanamycin-tobramycin-resistant methicillin-susceptible (KTR-MSSA) were phenotypically and genotypically examined for methicillin resistance. Among these tests, the diffusion method using the oxacillin and cefoxitin disks on Mueller-Hinton agar with and without NaCl, the incubation at 35 degrees C or 30 degrees C for 24 or 48 hr, respectively, and the determination of oxacillin MICs by E-test were performed. We also examined the presence of the mecA gene by PCR and its product PBP 2a by the Slidex MRSA Detection test after induction by cefoxitin disk. All of the AS-MRSA strains (100%) were detected by the cefoxitin disk in all conditions and by the oxacillin disk on Mueller-Hinton agar with 2% of NaCl at 35 degrees C. Without NaCl, the sensitivity fell to 97.2% by oxacillin disk. The oxacillin MICs for these isolates ranged from 2 to 128 mg/L. The mecA gene determinant and its product PBP 2a were detected in all AS-MRSA strains. All KTR-MSSA strains were phenotypically methicillin-susceptible and oxacillin MICs were below or borderline of breakpoint (< or =2 mg/L). The mecA gene determinant and its product were detected in one strain. Pulsed-field gel electrophoresis (PFGE) was applied and revealed the presence of two major patterns A (36.9%) and B (46.2%) in AS-MRSA isolates and seven patterns in the KTR-MSSA strains.

  7. Continuous degradation of maltose: improvement in stability and catalytic properties of maltase (α-glucosidase) through immobilization using agar-agar gel as a support.

    PubMed

    Nawaz, Muhammad Asif; Karim, Asad; Aman, Afsheen; Marchetti, Roberta; Qader, Shah Ali Ul; Molinaro, Antonio

    2015-04-01

    Maltose degrading enzyme was immobilized within agar-agar support via entrapment method due to its industrial utilization. The maximum immobilization efficiency (82.77%) was achieved using 4.0% agar-agar keeping the diameter of bead up to 3.0 mm. The matrix entrapment showed maximum catalytic activity at pH 7.0 and temperature 65 °C. Substrate saturation kinetics showed that the K m of immobilized enzyme increased from 1.717 to 2.117 mM ml(-1) where as Vmax decreased from 8,411 to 7,450 U ml(-1 )min(-1) as compared to free enzyme. The immobilization significantly increased the stability of maltase against various temperatures and immobilized maltase retain 100% of its original activity after 2 h at 50 °C, whereas the free maltase only showed 60% residual activity under same condition. The reusability of entrapped maltase showed activity up to 12 cycles and retained 50% of activity even after 5th cycle. Storage stability of agar entrapped maltase retain 73% of its initial activity even after 2 months when stored at 30 °C while free enzyme showed only 37% activity at same storage conditions.

  8. Universal growth of microdomains and gelation transition in agar hydrogels.

    PubMed

    Boral, Shilpi; Saxena, Anita; Bohidar, H B

    2008-03-27

    Investigations were carried out on aqueous sols and gels of agar (extracted from red seaweed Gelidiella acerosa) to explore the growth of microdomains en route to gelation. Isothermal frequency sweep studies on gel samples revealed master plots showing power-law dependence of gel elastic modulus, |G*|, on oscillation frequency, omega as |G*| approximately omegan, independent of temperature, with 0.5Tg). The S(q,t) behavior close to the gel transition point (Tg approximately (38+/-3 degrees C determined from rheology) followed a stretched exponential function: S(t)=A exp(-t/ts)beta. The beta factor increased from 0.25 to 1 as the gel temperature approached 25 degrees C from Tg, and relaxation time, ts, showed a peak at T approximately 30 degrees C. The SLS data (in the sol state) suggested the scaling of scattered intensity, Is(q) approximately epsilon(-gamma) (epsilon=(T/Tg-1), T>Tg) with gamma=0.13+/-0.03, and the presence of two distinct domains characterized by a Guinier regime (low q) and a power-law regime (high q). Close to and above Tg (+2 degrees C), IS(q) scaled with q as Is(q) approximately q(-alpha) with alpha=2.2+/-0.2, which decreased to 1.4+/-1 just below Tg (-2 degrees C), implying a coil-helix transition for 0.2% (w/v) and 0.3% (w/v) samples. For a 0.01% sample, alpha=3.5+/-0.5 which

  9. A Hidden Pitfall in the Preparation of Agar Media Undermines Microorganism Cultivability

    PubMed Central

    Tanaka, Tomohiro; Kawasaki, Kosei; Daimon, Serina; Kitagawa, Wataru; Yamamoto, Kyosuke; Tamaki, Hideyuki; Tanaka, Michiko; Nakatsu, Cindy H.

    2014-01-01

    Microbiologists have been using agar growth medium for over 120 years. It revolutionized microbiology in the 1890s when microbiologists were seeking effective methods to isolate microorganisms, which led to the successful cultivation of microorganisms as single clones. But there has been a disparity between total cell counts and cultivable cell counts on plates, often referred to as the “great plate count anomaly,” that has long been a phenomenon that still remains unsolved. Here, we report that a common practice microbiologists have employed to prepare agar medium has a hidden pitfall: when phosphate was autoclaved together with agar to prepare solid growth media (PT medium), total colony counts were remarkably lower than those grown on agar plates in which phosphate and agar were separately autoclaved and mixed right before solidification (PS medium). We used a pure culture of Gemmatimonas aurantiaca T-27T and three representative sources of environmental samples, soil, sediment, and water, as inocula and compared colony counts between PT and PS agar plates. There were higher numbers of CFU on PS medium than on PT medium using G. aurantiaca or any of the environmental samples. Chemical analysis of PT agar plates suggested that hydrogen peroxide was contributing to growth inhibition. Comparison of 454 pyrosequences of the environmental samples to the isolates revealed that taxa grown on PS medium were more reflective of the original community structure than those grown on PT medium. Moreover, more hitherto-uncultivated microbes grew on PS than on PT medium. PMID:25281372

  10. Detection of Agar, by Analysis of Sugar Markers, Associated with Bacillus Anthracis Spores, After Culture

    SciTech Connect

    Wunschel, David S.; Colburn, Heather A.; Fox, Alvin; Fox, Karen F.; Harley, William M.; Wahl, Jon H.; Wahl, Karen L.

    2008-08-01

    Detection of small quantities of agar associated with spores of Bacillus anthracis could provide key information regarding its source or growth characteristics. Agar, widely used in growth of bacteria on solid surfaces, consists primarily of repeating polysaccharide units of 3,6-anhydro-L-galactose (AGal) and galactose (Gal) with sulfated and O-methylated galactoses present as minor constituents. Two variants of the alditol acetate procedure were evaluated for detection of potential agar markers associated with spores. The first method employed a reductive hydrolysis step, to stabilize labile anhydrogalactose, by converting to anhydrogalactitol. The second eliminated the reductive hydrolysis step simplifying the procedure. Anhydrogalactitol, derived from agar, was detected using both derivatization methods followed by gas chromatography-mass spectrometry (GC-MS) analysis. However, challenges with artefactual background (reductive hydrolysis) or marker destruction (hydrolysis) lead to the search for alternative sugar markers. A minor agar component, 6-O-methyl galactose (6-O-M gal), was readily detected in agar-grown but not broth-grown bacteria. Detection was optimized by the use of gas chromatography-tandem mass spectrometry (GC-MS-MS). With appropriate choice of sugar marker and analytical procedure, detection of sugar markers for agar has considerable potential in microbial forensics.

  11. Membrane-assisted culture of fungal mycelium on agar plates for RNA extraction and pharmacological analyses.

    PubMed

    Lange, Mario; Müller, Carolin; Peiter, Edgar

    2014-05-15

    Fungal mycelium grown in liquid culture is easy to harvest for RNA extraction and gene expression analyses, but liquid cultures often develop rather heterogeneously. In contrast, growth of fungal mycelium on agar plates is highly reproducible. However, this biological material cannot be harvested easily for downstream analyses. This article describes a PVDF (polyvinylidene difluoride) membrane-assisted agar plate culture method that enables the harvest of mycelium grown on agar plates. This culture method leads to a strongly reduced variation in gene expression between biological replicates and requires less growth space as compared with liquid cultures.

  12. Growth characteristics of Bacillus anthracis compared to other Bacillus spp. on the selective nutrient media Anthrax Blood Agar and Cereus Ident Agar.

    PubMed

    Tomaso, Herbert; Bartling, Carsten; Al Dahouk, Sascha; Hagen, Ralf M; Scholz, Holger C; Beyer, Wolfgang; Neubauer, Heinrich

    2006-01-01

    Anthrax Blood Agar (ABA) and Cereus Ident Agar (CEI) were evaluated as selective growth media for the isolation of Bacillus anthracis using 92 B. anthracis and 132 other Bacillus strains from 30 species. The positive predictive values for the identification of B. anthracis on ABA, CEI, and the combination of both were 72%, 71%, and 90%, respectively. Thus, less than 10% of all species were misidentified using both nutrient media. Species which might be misidentified as B. anthracis were B. cereus, B. mycoides, and B. thuringiensis. Particularly, 30% of B. weihenstephanensis strains were misidentified as B. anthracis.

  13. A fresh liver agar substrate for rearing small numbers of forensically important blow flies (Diptera: Calliphoridae)

    USGS Publications Warehouse

    Gruner, Susan V.; Slone, Daniel H.

    2014-01-01

    Forensically important calliphorids can be reared on a mixture of beef liver and agar. Small pieces of meat, especially fresh or frozen beef liver, will desiccate in 2–6 h, but this simple-to-make feeding substrate remains moist for at least 12 h at 25 and 30°C without desiccation, even in small (5 g) amounts. We determined the survivorship of small numbers of Chrysomya megacephala (F.) (first-instar larvae to adult eclosion) raised on 5 g of liver agar and fresh beef liver. We found that all larvae raised on 5 g of liver died due to desiccation, but survivorship on 5 g of liver agar was equivalent to that on larger (50 g) pieces of either liver agar or beef liver.

  14. A fresh liver agar substrate for rearing small numbers of forensically important blow flies (Diptera: Calliphoridae).

    PubMed

    Gruner, Susan V; Slone, Daniel H

    2014-05-01

    Forensically important calliphorids can be reared on a mixture of beef liver and agar. Small pieces of meat, especially fresh or frozen beef liver, will desiccate in 2-6 h, but this simple-to-make feeding substrate remains moist for at least 12 h at 25 and 30 degrees C without desiccation, even in small (5 g) amounts. We determined the survivorship of small numbers of Chrysomya megacephala (F.) (first-instar larvae to adult eclosion) raised on 5 g of liver agar and fresh beef liver. We found that all larvae raised on 5 g of liver died due to desiccation, but survivorship on 5 g of liver agar was equivalent to that on larger (50 g) pieces of either liver agar or beef liver.

  15. Proton beam writing of microstructures in Agar gel for patterned cell growth

    NASA Astrophysics Data System (ADS)

    Larisch, Wolfgang; Koal, Torsten; Werner, Ronald; Hohlweg, Marcus; Reinert, Tilo; Butz, Tilman

    2011-10-01

    A rather useful prerequisite for many biological and biophysical studies, e.g., for cell-cell communication or neuronal networks, is confined cell growth on micro-structured surfaces. Solidified Agar layers have smooth surfaces which are electrically neutral and thus inhibit receptor binding and cell adhesion. For the first time, Agar microstructures have been manufactured using proton beam writing (PBW). In the irradiated Agar material the polysaccharides are split into oligosaccharides which can easily be washed off leaving Agar-free areas for cell adhesion. The beam diameter of 1 μm allows the fabrication of compartments accommodating single cells which are connected by micrometer-sized channels. Using the external beam the production process is very fast. Up to 50 Petri dishes can be produced per day which makes this technique very suitable for biological investigations which require large throughputs.

  16. Xanthan gum: an economical partial substitute for agar in microbial culture media.

    PubMed

    Babbar, Shashi B; Jain, Ruchi

    2006-04-01

    Xanthan gum, microbial desiccation-resistant polysaccharide prepared commercially by aerobic submerged fermentation from Xanthomonas campestris, has been successfully used alone and in combination with agar for microbial culture media. As illustrative examples, eight bacteria and eight fungi were grown on media solidified with either agar (A, 1.5%), xanthan gum (X, 1%), or combinations of both (0.9% X + 0.1% A, 0.8% X + 0.2% A, 0.7% X + 0.3% A, 0.6% X + 0.4% A). All fungi and bacteria exhibited normal growth and differentiation in all these treatments. Rather, growth of most of the fungi was better on xanthan (alone) and xanthan + agar media than agar medium. As the media gelled with xanthan gum alone flow, it was not possible to incubate Petri plates in inverted position. Moreover, because of the softness, streaking of bacteria was difficult on such media. However, these problems could be overcome by partially replacing xanthan gum with 0.3% agar. Bacterial enumeration studies carried out for Serratia sp. and Pseudomonas sp. by serial dilution and pour-plate method on agar (1.5%), 0.7%/0.6% X + 0.3%/0.4% A yielded similar counts. Selective media, succinate medium for Pseudomonas sp., and MacConkey broth medium for Escherichia coli gelled with 0.7%/0.6% X + 0.3%/0.4% A did not support growth of other bacteria when inoculated along with the above-mentioned bacteria. Likewise, differential medium, CRMA (Congo red mannitol agar) gelled with xanthan-agar combination could differentiate between Agrobacterium tumefaciens and Rhizobium sp.

  17. Genome Sequence of the Agar-Degrading Marine Bacterium Alteromonadaceae sp. Strain G7

    PubMed Central

    Kwak, Min-Jung; Song, Ju Yeon; Kim, Byung Kwon; Chi, Won-Jae; Kwon, Soon-Kyeong; Choi, Soobeom; Chang, Yong-Keun

    2012-01-01

    Here, we present the high-quality draft genome sequence of the agar-degrading marine gammaproteobacterium Alteromonadaceae sp. strain G7, which was isolated from coastal seawater to be utilized as a bioresource for production of agar-derived biofuels. The 3.91-Mb genome contains a number of genes encoding algal polysaccharide-degrading enzymes such as agarases and sulfatases. PMID:23209220

  18. Isolation of Asticcacaulis sp. SA7, a novel agar-degrading alphaproteobacterium.

    PubMed

    Hosoda, Akifumi; Sakai, Masao

    2006-03-01

    An agar-degrading bacterium, strain SA7, was isolated from plant roots cultivated in soil. Analysis of the 16S rDNA sequence showed that strain SA7 is affiliated with the genus Asticcacaulis. Strain SA7 produced extracellular agarase, and grew utilizing agar in the culture medium as sole carbon source. Zymogram analysis showed that strain SA7 extracellularly secreted single agarase protein (about 70 kDa).

  19. Low density, microcellular, dopable, agar/gelatin foams for pulsed power experiments

    SciTech Connect

    McNamara, W.F.; Aubert, J.H.

    1997-04-01

    Low-density, microcellular foams prepared from the natural polymers agar and gelatin have been developed for pulsed-power physics experiments. Numerous experiments were supported with foams having densities at or below 10 mg/cm{sup 3}. For some of the experiments, the agar/gelatin foam was uniformly doped with metallic elements using soluble salts. Depending on the method of preparation, cell sizes were typically below 10 microns and for one process were below 1.0 micron.

  20. Growth and phenotypic characterization of Legionella species on semisolid media made with washed agar.

    PubMed Central

    Rogers, J E; Jones, G W; Engleberg, N C

    1993-01-01

    Legionella pneumophila (and 28 Legionella species) grew efficiently on charcoal-free, buffered yeast extract medium made with washed agar and without apparent loss of infectivity for U937 cells. Because charcoal-free, buffered yeast extract is transparent, it is a suitable base for indicator media and pigment detection. In standard media, charcoal apparently prevents agar contaminants from inhibiting Legionella growth. Images PMID:8417021

  1. [GROWTH OF MICROMYCETES FROM DIFFERENT ECOLOGICAL NICHES ON AGAR NUTRIENT MEDIA].

    PubMed

    Kurchenko, I M; Yurieva, E M; Voychuk, S I

    2015-01-01

    Radial growth rate of (K(r)) 153 strains 6 species of micromycetes from different ecological niches was studied on 7 agar media: three standard (malt extract agar, potato-dextrose agar, Czapek's agar), and on agar media with plant polymers (carboxymethylcellulose, xylan, soluble starch and apple pectin). Endophytic and plant pathogenic strains (biotrophs) of all studied species did not differ significantly in their ability to grow on nutrient media of different composition--average values of K(r) for these two groups were the same (0,200 and 0,199 mm/h, respectively). Soil micromycetes (saprophytes) characterized by the lowest average growth rate (0,169 mm/h) and significantly differed from the endophytic and plant pathogenic ones. Average of the radial growth rates of studied microscopic fungi were higher on standard nutrient media than with plant polymers ones. Growth parameters of endophytes and plant pathogens of all studied species on various agar media differed from the soil strains. High growth rate of endophytic and plant pathogenic strains of Fusarium poae, Alternaria alternata and Ceratocystis sp. provides them the rapid colonization of plants. Penicillium funiculosum strains equally can exist as saprophytes in soil and as endophytic plant symbionts. A wide range of K(r) variation of endophytic dark pigmented Mycelia sterilia indicates the presence in this group of different species of micromycetes, which have no sporulation.

  2. Complex impedance and conductivity of agar-based ion-conducting polymer electrolytes

    NASA Astrophysics Data System (ADS)

    Nwanya, A. C.; Amaechi, C. I.; Udounwa, A. E.; Osuji, R. U.; Maaza, M.; Ezema, F. I.

    2015-04-01

    Agar-based electrolyte standing films with different salts and weak acids as ion and proton conductors were prepared and characterized by X-ray diffraction, UV-visible spectrophotometry, photoluminescence emission spectroscopy and electrochemical impedance spectroscopy. The salts used are lithium perchlorate (LiClO4) and potassium perchlorate (KClO4), while the weak acids used are acetic acid (CH3COOH) and lactic acid (C3H6O3). The values of the ion conductivity obtained for the agar-based polymer films are 6.54 × 10-8, 9.12 × 10-8, 3.53 × 10-8, 2.24 × 10-8 S/cm for the agar/acetic acid, agar/lactic acid, agar/LiClO4 and agar/KClO4 polymer films, respectively. As a function of temperature, the ion conductivity exhibits an Arrhenius behavior and the estimated activation energy is ≈0.1 eV for all the samples. The samples depicted high values of dielectric permittivity toward low frequencies which is due mostly to electrode polarization effect. The samples showed very high transparency (85-98 %) in the visible region, and this high transparency is one of the major requirements for application in electrochromic devices (ECD). The values of conductivity and activation energy obtained indicate that the electrolytes are good materials for application in ECD.

  3. Modification of kanamycin-esculin-azide agar to improve selectivity in the enumeration of fecal streptococci from water samples.

    PubMed Central

    Audicana, A; Perales, I; Borrego, J J

    1995-01-01

    Kanamycin-esculin-azide agar was modified by increasing the concentration of sodium azide to 0.4 g liter-1 and replacing kanamycin sulfate with 5 mg of oxolinic acid liter-1. The modification, named oxolinic acid-esculin-azide (OAA) agar, was compared with Slanetz-Bartley and KF agars by using drinking water and seawater samples. The OAA agar showed higher specificity, selectivity, and recovery efficiencies than those obtained by using the other media. In addition, no confirmation of typical colonies was needed when OAA agar was used, which significantly shortens the time of sample processing and increases the accuracy of the method. PMID:8534085

  4. Augmentation of antibiotic activity by low-frequency electric and electromagnetic fields examining Staphylococcus aureus in broth media.

    PubMed

    Matl, F D; Obermeier, A; Zlotnyk, J; Friess, W; Stemberger, A; Burgkart, R

    2011-07-01

    Systemic treatment of biomaterial-associated bacterial infections with high doses of antibiotics is an established therapeutic concept. The purpose of this in vitro study was to determine the influence of magnetic, electromagnetic, and electric fields on gentamicin-based, antibiotic therapy. It has been previously reported that these fields are successful in the treatment of bone healing and reducing osteitis in infected tibia-pseudarthroses. Four separate experimental setups were used to expose bacterial cultures of Staphylococcus aureus both in Mueller-Hinton broth (MHB) and on Mueller-Hinton agar (MHA), in the presence of gentamicin, to (1) a low-frequency magnetic field (MF) 20 Hz, 5 mT; (2) a low-frequency MF combined with an additional alternating electric field (MF + EF) 20 Hz, 5 mT, 470 mV/cm; (3) a sinusoidal alternating electric field (EF AC) 20 Hz, 470 mV/cm; and (4) a direct current electric field (EF DC) 588 mV/cm. No significant difference between samples and controls was detected on MHA. However, in MHB each of the four fields applied showed a significant growth reduction of planktonically grown Staphylococcus aureus in the presence of gentamicin between 32% and 91% within 24 h of the experiment. The best results were obtained by a direct current EF, decreasing colony-forming units (CFU)/ml more than 91%. The application of electromagnetic fields in the area of implant and bone infections could offer new perspectives in antibiotic treatment and antimicrobial chemotherapy.

  5. Performance of CHROMAGAR candida and BIGGY agar for identification of yeast species

    PubMed Central

    Yücesoy, Mine; Marol, Serhat

    2003-01-01

    Background The importance of identifying the pathogenic fungi rapidly has encouraged the development of differential media for the presumptive identification of yeasts. In this study two differential media, CHROMagar Candida and bismuth sulphite glucose glycine yeast agar, were evaluated for the presumptive identification of yeast species. Methods A total number of 270 yeast strains including 169 Candida albicans, 33 C. tropicalis, 24 C. glabrata, 18 C. parapsilosis, 12 C. krusei, 5 Trichosporon spp., 4 C. kefyr, 2 C. lusitaniae, 1 Saccharomyces cerevisiae and 1 Geotrichum candidum were included. The strains were first identified by germ tube test, morphological characteristics on cornmeal tween 80 agar and Vitek 32 and API 20 C AUX systems. In parallel, they were also streaked onto CHROMagar Candida and bismuth sulphite glucose glycine yeast agar plates. The results were read according to the color, morphology of the colonies and the existance of halo around them after 48 hours of incubation at 37°C. Results The sensitivity and specificity values for C. albicans strains were found to be 99.4, 100% for CHROMagar Candida and 87.0, 75.2% for BiGGY agar, respectively. The sensitivity of CHROMagar Candida to identify C. tropicalis, C. glabrata and C. krusei ranged between 90.9 and 100% while the specificity was 100%. The sensitivity rates for BiGGY agar were 66.6 and 100% while the specificity values were found to be 95.4 and 100% for C. tropicalis and C. krusei, respectively. Conclusions It can be concluded that the use of CHROMagar Candida is an easy and reliable method for the presumptive identification of most commonly isolated Candida species especially C. albicans, C. tropicalis and C. krusei. The lower sensitivity and specificity of BiGGY agar to identify commonly isolated Candida species potentially limits the clinical usefulness of this agar. PMID:14613587

  6. Mass production of spores of lactic acid-producing Rhizopus oryzae NBRC 5384 on agar plate.

    PubMed

    Yamane, Tsuneo; Tanaka, Ryosuke

    2013-01-01

    Mass production of sporangiospores (spores) of Rhizopus oryzae NBRC 5384 (identical to NRRL 395 and ATCC 9363) on potato-dextrose-agar medium was studied aiming at starting its L(+)-lactic acid fermentation directly from spore inoculation. Various parameters including harvest time, sowed spore density, size of agar plate, height of air space, and incubation mode of plate (agar-on-bottom or agar-on-top) were studied. Ordinarily used shallow Petri dishes were found out to be unsuitable for the full growth of R. oryzae sporangiophores. In a very wide range of the sowed spore density, the smaller it was, the greater the number of the harvested spores was. It was also interesting to find out that R. oryzae grown downward vertically with a deep air space in an agar-on-top mode gave larger amount of spores than in an agar-on-bottom mode at 30°C for 7-day cultivation. Scale-up of the agar plate culture from 26.4 to 292 cm(2) was studied, resulting in the proportional relationship between the number of the harvested spores/plate and the plate area in the deep Petri dishes. The number of plates of 50 cm in diameter needed for 100 m(3) industrial submerged fermentation started directly from 2 × 10(5) spores/mL inoculum size was estimated as about 6, from which it was inferred that such a fermentation would be feasible. Designing a 50 cm plate and a method of spreading and collecting the spores were suggested. Bioprocess technological significance of the "full-scale industrial submerged fermentation started directly from spore inoculation omitting pre-culture" has been discussed.

  7. Evaluation of CP Chromo Select Agar for the enumeration of Clostridium perfringens from water.

    PubMed

    Manafi, Mammad; Waldherr, Kerstin; Kundi, Michael

    2013-10-01

    The European Directive on drinking water quality has included mCP agar as the reference method for recovering Clostridium perfringens from drinking waters. In the present study, three media (mCP, TSCF and CP Chromo Select Agar) were evaluated for recovery of C. perfringens in different surface water samples. Out of 139 water samples, using a membrane filtration technique, 131 samples (94.2%) were found to be presumptively positive for C. perfringens in at least one of the culture media. Green colored colonies on CP Chromo Select Agar (CCP agar) were counted as presumptive C. perfringens isolates. Out of 483 green colonies on CCP agar, 96.3% (465 strains, indole negative) were identified as C. perfringens, and 15 strains (3.1%) were indole positive and were identified as Clostridium sordellii, Clostridium bifermentans or Clostridium tetani. Only 3 strains (0.6%) gave false positive results and were identified as Clostridium fallax, Clostridium botulinum, and Clostridium tertium. Variance analysis of the data obtained shows statistically no significant differences in the counts obtained between media employed in this work. The mCP method is very onerous for routine screening and bacterial colonies could not be used for further biochemical testing. The colonies on CCP and TSCF were easy to count and subculture for confirmation tests. TSCF detects sulfite-reducing clostridia, including species other than C. perfringens, and in some cases excessive blackening of the agar frustrated counting of the colonies. If the contamination was too high, TSCF did not consistently produce black colonies and as a consequence, the colonies were white and gave false negative results. On the other hand, the identification of typical and atypical colonies isolated from all media demonstrated that CCP agar was the most useful medium for C. perfringens recovery in water samples.

  8. Preparation and characterization of bio-nanocomposite films of agar and silver nanoparticles: laser ablation method.

    PubMed

    Rhim, Jong-Whan; Wang, Long-Feng; Lee, Yonghoon; Hong, Seok-In

    2014-03-15

    Silver nanoparticles (AgNPs) were prepared by a laser ablation method and composite films with the AgNPs and agar were prepared by solvent casting method. UV-vis absorbance test and transmission electron microscopy (TEM) analysis results revealed that non-agglomerated spherical AgNPs were formed by the laser ablation method. The surface color of the resulting agar/AgNPs films exhibited the characteristic plasmonic effect of the AgNPs with the maximum absorption peaks of 400-407 nm. X-ray diffraction (XRD) test results also exhibited characteristic AgNPs crystals with diffraction peaks observed at 2θ values of 38.39°, 44.49°, and 64.45°, which were corresponding to (111), (200), and (220) crystallographic planes of face-centered cubic (fcc) silver crystals, respectively. Thermogravimetric analysis (TGA) results showed that thermal stability of the agar/AgNPs composite films was increased by the inclusion of metallic silver. Water vapor barrier properties and surface hydrophobicity of the agar/AgNPs films increased slightly with the increase in AgNPs content but they were not statistically significant (p>0.05), while mechanical strength and stiffness of the composite films decreased slightly (p<0.05). The agar/AgNPs films exhibited distinctive antimicrobial activity against both Gram-positive (Listeria monocytogenes) and Gram-negative (Escherichia coli O157:H7) bacterial pathogens.

  9. Strongyloidiasis detected by the agar plate culture method among patients infected by HIV.

    PubMed

    Urdez-Hernández, E; Jiménez-Galán, S; Antonio-Manríquez, M; DE León-Juárez, E A; Terrazas-Estrada, J J; Hernández-García, M C; García-Zaldívar, P; Estrada-Aguilera, A

    1999-10-01

    To evaluate the rate of strongyloidiasis among HIV/AIDS patients, stools and duodenal juice were examined using the agar plate culture method. From January to June 1993, a total of 60 HIV/AIDS patients were required for duodenal aspirate and three serial samples of freshly passed stools. Stools and duodenal aspirate were dispensed on an agar plate culture; after incubation at 28 degrees C during 48 h, screening of plates was made at 10 x. The presence of furrows and worms of short buccal chamber and prominent genital primordium were positive for Strongyloides stercoralis. Most patients were men (91.7%); their mean age, of 33.9 years (SD +/- 10.6); their median CD4(+) T-cells count, of 105/microL (range of 12 to 646). S. stercoralis was detected in three patients (5%). In duodenal juice, the three patients showed the parasite, but in feces, only two (3.3%). In these two individuals, the worms were found in feces by agar culture and Faust's concentration method. The rate of S. stercoralis in feces of HIV/AIDS individuals (3.3%) by agar culture method was similar to that formerly reported from the general Mexican population (2.9%) using standard concentration procedures. Hence, in this immunocompromised population of a low prevalence city, there was no advantage to using an agar plate culture for strongyloidiasis.

  10. Characterization of bionanocomposite films prepared with agar and paper-mulberry pulp nanocellulose.

    PubMed

    Reddy, Jeevan Prasad; Rhim, Jong-Whan

    2014-09-22

    Crystallized nanocellulose (CNC) was separated from paper-mulberry (Broussonetia kazinoki Siebold) bast pulp by sulfuric acid hydrolysis method and they were blended with agar to prepare bionanocomposite films. The effect of CNC content (1, 3, 5 and 10 wt% based on agar) on the mechanical, water vapor permeability (WVP), and thermal properties of the nanocomposites were studied. Changes of the cellulose fibers in structure, morphology, crystallinity, and thermal properties of the films were evaluated using FT-IR, TEM, SEM, XRD, and TGA analysis methods. The CNC was composed of fibrous and spherical or elliptic granules of nano-cellulose with sizes of 50-60 nm. Properties of agar film such as mechanical and water vapor barrier properties were improved significantly (p<0.05) by blending with the CNC. The tensile modulus and tensile strength of agar film increased by 40% and 25%, respectively, in the composite film with 5 wt% of CNC, and the WVP of agar film decreased by 25% after formation of nanocomposite with 3 wt% of CNC. The CNC obtained from the paper-mulberry bast pulp can be used as a reinforcing agent for the preparation of bio-nanocomposites, and they have a high potential for the development of completely biodegradable food packaging materials.

  11. Strategies to improve the mechanical strength and water resistance of agar films for food packaging applications.

    PubMed

    Sousa, Ana M M; Gonçalves, Maria P

    2015-11-05

    Agar films possess several properties adequate for food packaging applications. However, their high cost-production and quality variations caused by physiological and environmental factors affecting wild seaweeds make them less attractive for industries. In this work, native (NA) and alkali-modified (AA) agars obtained from sustainably grown seaweeds (integrated multi-trophic aquaculture) were mixed with locust bean gum (LBG) to make 'knife-coated' films with fixed final concentration (1 wt%) and variable agar/LBG ratios. Agar films were easier to process upon LBG addition (viscosity increase and gelling character decrease of the film-forming solutions observed by dynamic oscillatory and steady shear measurements). The mechanical properties and water resistance were optimal for films with 50 and/or 75% LBG contents and best in the case of NA (cheaper to extract). These findings can help reduce the cost-production of agar packaging films. Moreover, the controlled cultivation of seaweeds can provide continuous and reliable feedstock for transformation industries.

  12. Immobilization of urease from pigeonpea (Cajanus cajan) on agar tablets and its application in urea assay.

    PubMed

    Mulagalapalli, Swati; Kumar, Sandeep; Kalathur, Ravi Charan Reddy; Kayastha, Arvind M

    2007-09-01

    The pigeonpea urease was immobilized on agar, a common gelling substance. The tablet strips were used as moulds to cast agar tablets of uniform shape and size. The time and temperature of solidification of agar was 6 min and 44 degrees C, respectively. The 5 % agar (w/v) and 0.019 mg protein/agar tablet yielded an optimum immobilization of 51.7%. The optimum pH was shifted through 0.2 U (from 7.3 to 7.5) towards basic side upon immobilization. The optimum temperature of soluble and immobilized urease was 30 degrees C and 60 degrees C, respectively, showing the improvement in thermal stability of urease. There was an increase in K m from 3.23 to 5.07 mM after immobilization. The half-lives of soluble and immobilized urease were 21 and 53 days, respectively, at pH 7.3 and 4 degrees C. The urea was estimated in different blood samples with the help of immobilized urease and the results were consistent with those from clinical pathology laboratory through an autoanalyzer (Zydus Co., Rome, Italy).

  13. Comparison of agar-based media for primary isolation of glycopeptide-resistant enterococci.

    PubMed

    Chadwick, P. R.; Brown, D. F. J.; Wilcox, M. H.; Collyns, T. A.; Walpole, E.; Dillon, J.; Smith, R.; Gopal Rao, G.; Oppenheim, B. A.

    1997-01-01

    OBJECTIVE: To compare four vancomycin-containing agar media for the isolation of glycopeptide-resistant enterococci (GRE) from clinical fecal specimens: kanamycin---aesculin---azide (KAA) agar; bile---aesculin---polymixin (BAP) agar; aztreonam---amphotericin blood (CBAA) agar; and neomycin blood (CBN) agar. METHODS: Fecal specimens from 125 patients were inoculated onto each medium. Media were examined for enterococci after incubation for up to 48 h. Enterococci were identified to species level, and glycopeptide phenotypes were determined by measuring minimum inhibitory concentrations of vancomycin and teicoplanin. RESULTS: GRE were isolated from 44/125 samples. Enterococcus faecalis and Enterococcus faecium isolates, expressing glycopeptide resistance of the VanA or VanB phenotypes, were recovered from 27/33 (82%) specimens on BAP medium, 26/33 (79%) on KAA medium, and 21/33 (64%) on CBN and CBAA media. Enterococcus gallinarum and Enterococcus casseliflavus isolates expressing low-level glycopeptide resistance (VanC phenotype) were recovered from 14/15 (93%) specimens on CBAA medium, 7/15 (47%) on KAA and CBN media, and 6/15 (40%) on BAP medium. CONCLUSIONS: The media tested in this study, with the exception of CBN medium, detected at least 75% of patients colonized by GRE. Further development of BAP, CBAA and KAA media is warranted to improve growth and selectivity.

  14. Antimicrobial and physical-mechanical properties of agar-based films incorporated with grapefruit seed extract.

    PubMed

    Kanmani, Paulraj; Rhim, Jong-Whan

    2014-02-15

    The use of synthetic petroleum based packaging films caused serious environmental problems due to their difficulty in recycling and poor biodegradability. Therefore, present study was aimed to develop natural biopolymer-based antimicrobial packaging films as an alternative for the synthetic packaging films. As a natural antimicrobial agent, grapefruit seed extract (GSE) has been incorporated into agar to prepare antimicrobial packaging film. The films with different concentrations of GSE were prepared by a solvent casting method and the resulting composite films were examined physically and mechanically. In addition, the films were characterized by FE-SEM, XRD, FT-IR and TGA. The incorporation of GSE caused increase in color, UV barrier, moisture content, water solubility and water vapor permeability, while decrease in surface hydrophobicity, tensile strength and elastic modulus of the films. As the concentration of GSE increased from 0.6 to 13.3 μg/mL, the physical and mechanical properties of the films were affected significantly. The addition of GSE changed film microstructure of the film, but did not influence the crystallinity of agar and thermal stability of the agar-based films. The agar/GSE films exhibited distinctive antimicrobial activity against three test food pathogens, such as Listeria monocytogenes, Bacillus cereus and Escherichia coli. These results suggest that agar/GSE films have potential to be used in an active food packaging systems for maintaining food safety and extending the shelf-life of the packaged food.

  15. Effects of shape and size of agar gels on heating uniformity during pulsed microwave treatment.

    PubMed

    Soto-Reyes, Nohemí; Temis-Pérez, Ana L; López-Malo, Aurelio; Rojas-Laguna, Roberto; Sosa-Morales, María Elena

    2015-05-01

    Model gel systems with different shape (sphere, cylinder, and slab) and size (180 and 290 g) were prepared with agar (5%) and sucrose (5%). Dielectric constant (ε'), loss factor (ε"), thermophysical properties, and temperature distribution of the model system were measured. Each agar model system was immersed and suspended in water, and then, heated in a microwave oven with intermittent heating until the core temperature reached 50 °C. The ε' and ε" of agar gels decreased when frequency increased. The density and thermal conductivity values of the agar gels were 1033 kg/m(3) and 0.55 W/m °C, respectively. The temperature distribution of sphere, cylinder, and slab was different when similar power doses were applied. The slab reached 50 °C in less time (10 min) and showed a more uniform heating than spheres and cylinders in both sizes. Agar model systems of 180 g heated faster than those of 290 g. The coldest point was the center of the model systems in all studied cases. Shape and size are critical food factors that affect the heating uniformity during microwave heating processes.

  16. Homogeneous Matrix Deposition on Dried Agar for MALDI Imaging Mass Spectrometry of Microbial Cultures

    NASA Astrophysics Data System (ADS)

    Hoffmann, Thomas; Dorrestein, Pieter C.

    2015-11-01

    Matrix deposition on agar-based microbial colonies for MALDI imaging mass spectrometry is often complicated by the complex media on which microbes are grown. This Application Note demonstrates how consecutive short spray pulses of a matrix solution can form an evenly closed matrix layer on dried agar. Compared with sieving dry matrix onto wet agar, this method supports analyte cocrystallization, which results in significantly more signals, higher signal-to-noise ratios, and improved ionization efficiency. The even matrix layer improves spot-to-spot precision of measured m/z values when using TOF mass spectrometers. With this technique, we established reproducible imaging mass spectrometry of myxobacterial cultures on nutrient-rich cultivation media, which was not possible with the sieving technique.

  17. Possible influence of surfactants and proteins on the efficiency of contact agar microbiological surface sampling.

    PubMed

    Deckers, Sylvie M; Sindic, Marianne; Anceau, Christine; Brostaux, Yves; Detry, Jean G

    2010-11-01

    Agar contact microbiological sampling techniques, based on a transfer of the microorganisms present on a surface to a culture medium, are widely used to assess and control surface cleanliness and to evaluate microbial contamination levels. The effectiveness of these techniques depends on many environmental parameters that influence the strength of attachment of the bacteria to the surface. In the present study, stainless steel and high density polyethylene surfaces were inoculated with known concentrations of Staphylococcus epidermidis. Following an experimental design, the surfaces were sampled with different types of replicate organism direct agar contact plates and Petrifilm; results indicated that recovery rates were influenced by the presence of egg white albumin or Tween 80 in the inoculum solutions or by the introduction of surfactants into the contact agar of the microbiological sampling techniques. The techniques yielded significantly different results, depending on sampling conditions, underlining the need for a standardization of laboratory experiments to allow relevant comparisons of such techniques.

  18. Improved soft-agar colony assay in a fluid processing apparatus.

    PubMed

    Forsman, A D; Herpich, A R; Chapes, S K

    1999-01-01

    The standard method for quantitating bone marrow precursor cells has been to count the number of colony-forming units that form in semisolid (0.3%) agar. Recently we adapted this assay for use in hardware, the Fluid Processing Apparatus, that is flown in standard payload lockers of the space shuttle. When mouse or rat macrophage colony-forming units were measured with this hardware in ground-based assays, we found significantly more colony growth than that seen in standard plate assays. The improved growth correlates with increased agar thickness but also appears to be due to properties inherent to the Fluid Processing Apparatus. This paper describes an improved method for determining bone marrow macrophage precursor numbers in semisolid agar.

  19. [DNA and chemical analyses of commercial fly agaric-related products].

    PubMed

    Maruyama, Takuro; Kawahara, Nobuo; Fukiharu, Toshimitsu; Yokoyama, Kazumasa; Makino, Yukiko; Goda, Yukihiro

    2005-04-01

    Since June 6, 2002, psilocin and psilocybin-containing fungi (commonly called "magic mushrooms") have been regulated by the Narcotics and Psychotropics Control Law in Japan. However, various fly agaric-related products are now entering the Japanese market via the internet. In this study, fly agaric-related products available in this way were investigated for raw materials by DNA analysis and for additives by chemical analysis. Nucleotide sequence analysis of the mitochondrial 12S rDNA region suggested that these fly agaric-related products originate from A. muscaria or A. muscaria var. persicina. Furthermore, they were classified into three strains based on the ITS2-LSU nucleotide sequence. Harmine derivatives and/or tryptamine derivatives were detected in some of these products by LC/MS analysis. In accordance with this, the matK gene of Peganum harmala was found in all of the harmine derivative-containing samples.

  20. Expression of an accessory cell phenotype by hairy cells during lymphocyte colony formation in agar culture.

    PubMed

    Farcet, J P; Gourdin, M F; Testa, U; Andre, C; Jouault, H; Reyes, F

    1983-01-01

    Human T lymphocytes require the cooperation of accessory cells to generate lymphocyte colonies in agar culture under PHA stimulation. Various hairy cell enriched fractions, as well as normal monocytes, have been found to be able to initiate colony formation by normal lymphocytes. Leukemic monocytes from CMML patients were also effective, but not the leukemic lymphocytes from CLL patients. The phenotype expressed by HC in agar colonies was further studied using cell surface and enzymatic markers. We have concluded that HC in agar culture in the presence of both normal T lymphocytes and PHA lose the B phenotype that they express in vivo and function like an accessory cell in contrast to normal or leukemic B lymphocytes.

  1. Eradication of bovine leukemia virus infection in commercial dairy herds using the agar gel immunodiffusion test.

    PubMed Central

    Shettigara, P T; Samagh, B S; Lobinowich, E M

    1986-01-01

    Demands for bovine leukemia virus test negative breeding cattle and for semen from bovine leukemia virus test negative bulls by several countries have encouraged the eradication of bovine leukemia virus infection from selected herds in Canada. This project was undertaken to evaluate the suitability of the agar gel immunodiffusion test, standardized to detect anti-bovine leukemia virus glycoprotein antibodies, for eradication of bovine leukemia virus from commercial dairy herds. Of nine participating herds, the prevalence rate of bovine leukemia virus infection was low (less than 10%) in three, medium (11-30%) in four and high (greater than 30%) in two. The herds were tested by the agar gel immunodiffusion test, reactors were removed and the herds were then retested at regular intervals. The results indicate that it is possible to eliminate bovine leukemia virus infection from the herds after two to three cycles of agar gel immunodiffusion tests and prompt removal of the reactors. PMID:3019498

  2. Use of Rambach Propylene Glycol Containing Agar for identification of Salmonella spp.

    PubMed

    Gruenewald, R; Henderson, R W; Yappow, S

    1991-10-01

    When grown on Rambach Propylene Glycol Containing Agar (Rambach agar), 216 of 230 (93.9%) Salmonella organisms isolated from patients and 54 of 62 (87.1%) Salmonella stock cultures produced a crimson-colored growth. Of the 14 clinical Salmonella isolates which displayed colors other than crimson, 8 were Salmonella typhi, 2 were Salmonella paratyphi A, and 4 belonged to other commonly isolated serotypes. All eight Salmonella stock cultures which failed to produce a crimson color belonged to rarely isolated serotypes. In contrast, of 83 non-Salmonella stock cultures distributed among 29 bacterial species, none produced a crimson color. These results suggest that while Rambach agar cannot preidentify S. typhi and S. paratyphi A, the medium can be used for the presumptive identification and can assist in the definitive identification of the overwhelming majority of Salmonella isolates.

  3. [Presumptive identification of Candida spp. and other clinically important yeasts: usefulness of Brilliance Candida Agar].

    PubMed

    Alfonso, Claudia; López, Mónica; Arechavala, Alicia; Perrone, María Del Carmen; Guelfand, Liliana; Bianchi, Mario

    2010-06-30

    Fungal infections caused by yeasts have increased during the last decades and invasive forms represent a serious problem for human health. Candida albicans is the species most frequently isolated from clinical samples. However, other emerging yeast pathogens are increasingly responsible for mycotic infections, and some of them are resistant to some antifungal drugs. Consequently, it is necessary to have methods that can provide a rapid presumptive identification at species level. Numerous chromogenic agar media have been shown to be of value as diagnostic tools. We have compared a chromogenic medium, Brilliance Candida Agar, with CHROMagar Candida, the chromogenic medium most used in our country. A multicentre study was conducted in 16 Hospitals belonging to the Mycology Net of Buenos Aires City Government. A total of 240 yeast isolates were included in this research. The new chromogenic agar showed results very similar to those obtained with CHROMagar Candida.

  4. Agar blue localization of small pulmonary nodules and ground glass opacifications for thoracoscopic resection

    PubMed Central

    2016-01-01

    Background Screening for lung cancer using high resolution computed tomography (CT) has produced encouraging early results. Extremely small nodules and non-palpable areas of opacifications are able to be detected, but pose a challenge to the thoracic surgeon trying to resect these areas. Methods Forty five patients with ground glass opacifications (GGOs) or small pulmonary nodules underwent pre-operative CT-guided placement of methylene blue dyed agar and/or hook wire needle localization prior to thoracoscopic resection. Progel was applied to any intraoperative air leaks observed after successful resection. Results All lesions were successfully excised thoracoscopically. The blue agar aided in localization of these areas and did not affect the histological architecture during pathologic evaluation. Conclusions Careful pre-operative evaluation and planning, including use of selective CT-guided blue agar localization and hook wire placement, may greatly assist in thoracoscopically locating and resecting these often difficult-to-visualize lesions. PMID:28066669

  5. Agar-block microcosms for controlled plant tissue decomposition by aerobic fungi.

    PubMed

    Schilling, Jonathan S; Jacobson, K Brook

    2011-02-03

    The two principal methods for studying fungal biodegradation of lignocellulosic plant tissues were developed for wood preservative testing (soil-block; agar-block). It is well-accepted that soil-block microcosms yield higher decay rates, fewer moisture issues, lower variability among studies, and higher thresholds of preservative toxicity. Soil-block testing is thus the more utilized technique and has been standardized by American Society for Testing and Materials (ASTM) (method D 1413-07). The soil-block design has drawbacks, however, using locally-variable soil sources and in limiting the control of nutrients external (exogenous) to the decaying tissues. These drawbacks have emerged as a problem in applying this method to other, increasingly popular research aims. These modern aims include degrading lignocellulosics for bioenergy research, testing bioremediation of co-metabolized toxics, evaluating oxidative mechanisms, and tracking translocated elements along hyphal networks. Soil-blocks do not lend enough control in these applications. A refined agar-block approach is necessary. Here, we use the brown rot wood-degrading fungus Serpula lacrymans to degrade wood in agar-block microcosms, using deep Petri dishes with low-calcium agar. We test the role of exogenous gypsum on decay in a time-series, to demonstrate the utility and expected variability. Blocks from a single board rip (longitudinal cut) are conditioned, weighed, autoclaved, and introduced aseptically atop plastic mesh. Fungal inoculations are at each block face, with exogenous gypsum added at interfaces. Harvests are aseptic until the final destructive harvest. These microcosms are designed to avoid block contact with agar or Petri dish walls. Condensation is minimized during plate pours and during incubation. Finally, inoculum/gypsum/wood spacing is minimized but without allowing contact. These less technical aspects of agar-block design are also the most common causes of failure and the key source of

  6. New Agar Technique Compared with Sand Flotation for Obtaining Salt Marsh Culicoides mississippiensis Hoffman (Diptera: Ceratopogonidae) Larvae,

    DTIC Science & Technology

    1979-12-26

    compared with 1% and 2% (wt/v) agar formulations for extracting Culicoides ndisaiooippiensis Hoffman larvae from marsh soil samples. The 1% agar formula...been used to recover larvae of biting midges (CuZ.,o;1aa spp .) from salt marsh substrate (soil) samples. They are: (1) sieve-flotation (Kettle and Lawson...Kettle et al., (1975) in which tabanid and culicoid larvae were successfully reared in agar media, we decided that one possibility was to replace the

  7. Effects of medium and inoculum variations on screening for high-level aminoglycoside resistance in Enterococcus faecalis.

    PubMed Central

    Sahm, D F; Torres, C

    1988-01-01

    Enterococcus faecalis isolates that are refractory to aminoglycoside-penicillin synergy can be detected by their ability to grow in the presence of high concentrations of aminoglycoside (2,000 micrograms/ml). In past studies investigators have used a variety of media and inoculum sizes to perform high-level aminoglycoside resistance screens, but little is known about how these variations affect test accuracy. We screened 63 E. faecalis strains on different media by using various inoculum sizes and correlated the results with synergy test results obtained by time-kill studies. Screens were done with dextrose-phosphate agar, brain heart infusion agar, Trypticase soy agar with 5% sheep blood, Mueller-Hinton agar with 5% sheep blood, dextrose-phosphate broth, and Mueller-Hinton broth. Agar screens were inoculated with 10(2), 10(4), and 10(6) CFU; and broth screens contained a final inoculum of 10(5) CFU/ml. The E. faecalis isolates were tested for high-level resistance to streptomycin, kanamycin, amikacin, gentamicin, and tobramycin. Of the 63 isolates tested, 21 did not show high-level resistance to any of the aminoglycosides tested, and 42 demonstrated high-level resistance to one or more drugs. The sensitivity of most screens was greater than or equal to 90%. Regardless of the inoculum size or medium used, false-resistance results were seldom encountered. Screen specificity, which was used as the indicator of false susceptibility, was markedly influenced by both the inoculum size and the drug being tested. Specificity was low whenever a 10(2)-CFU inoculum was used, when amikacin was tested with any inoculum, and when tobramycin was tested in broth media. Data for kanamycin could be used to predict amikacin-penicillin synergy, and the highly accurate gentamicin screen obviated the need for the testing of tobramycin. We recommend a 10(6) -CFU inoculum for agar screens and a 10(5) -CFU/ml inoculum for broth screens. The type of medium used did not substantially

  8. Use of the Soft-agar Overlay Technique to Screen for Bacterially Produced Inhibitory Compounds

    PubMed Central

    Hockett, Kevin L.; Baltrus, David A.

    2017-01-01

    The soft-agar overlay technique was originally developed over 70 years ago and has been widely used in several areas of microbiological research, including work with bacteriophages and bacteriocins, proteinaceous antibacterial agents. This approach is relatively inexpensive, with minimal resource requirements. This technique consists of spotting supernatant from a donor strain (potentially harboring a toxic compound(s)) onto a solidified soft agar overlay that is seeded with a bacterial test strain (potentially sensitive to the toxic compound(s)). We utilized this technique to screen a library of Pseudomonas syringae strains for intraspecific killing. By combining this approach with a precipitation step and targeted gene deletions, multiple toxic compounds produced by the same strain can be differentiated. The two antagonistic agents commonly recovered using this technique are bacteriophages and bacteriocins. These two agents can be differentiated using two simple additional tests. Performing a serial dilution on a supernatant containing bacteriophage will result in individual plaques becoming less in number with greater dilution, whereas serial dilution of a supernatant containing bacteriocin will result a clearing zone that becomes uniformly more turbid with greater dilution. Additionally, a bacteriophage will produce a clearing zone when spotted onto a fresh soft agar overlay seeded with the same strain, whereas a bacteriocin will not produce a clearing zone when transferred to a fresh soft agar lawn, owing to the dilution of the bacteriocin. PMID:28117830

  9. Investigation of dental alginate and agar impression materials as a brain simulant for ballistic testing.

    PubMed

    Falland-Cheung, Lisa; Piccione, Neil; Zhao, Tianqi; Lazarjan, Milad Soltanipour; Hanlin, Suzanne; Jermy, Mark; Waddell, J Neil

    2016-06-01

    Routine forensic research into in vitro skin/skull/brain ballistic blood backspatter behavior has traditionally used gelatin at a 1:10 Water:Powder (W:P) ratio by volume as a brain simulant. A limitation of gelatin is its high elasticity compared to brain tissue. Therefore this study investigated the use of dental alginate and agar impression materials as a brain simulant for ballistic testing. Fresh deer brain, alginate (W:P ratio 91.5:8.5) and agar (W:P ratio 81:19) specimens (n=10) (11×22×33mm) were placed in transparent Perspex boxes of the same internal dimensions prior to shooting with a 0.22inch caliber high velocity air gun. Quantitative analysis to establish kinetic energy loss, vertical displacement elastic behavior and qualitative analysis to establish elasticity behavior was done via high-speed camera footage (SA5, Photron, Japan) using Photron Fastcam Viewer software (Version 3.5.1, Photron, Japan) and visual observation. Damage mechanisms and behavior were qualitatively established by observation of the materials during and after shooting. The qualitative analysis found that of the two simulant materials tested, agar behaved more like brain in terms of damage and showed similar mechanical response to brain during the passage of the projectile, in terms of energy absorption and vertical velocity displacement. In conclusion agar showed a mechanical and subsequent damage response that was similar to brain compared to alginate.

  10. Alternative plasticizers for the production of thermo-compressed agar films

    Technology Transfer Automated Retrieval System (TEKTRAN)

    One percent agar (% wt) was dissolved in the deep eutectic solvent (DES), (2-hydroxyethyl) trimethylammonium chloride/urea at a 1:2 molar ratio, and successfully Electrospun into nanofibers. An existing electrospinning set-up, operated at 50 deg C, was adapted for use with an ethanol bath to collect...

  11. Use of bile-esculin agar for rapid differentiation of Enterobacteriaceae.

    PubMed Central

    Lindell, S S; Quinn, P

    1975-01-01

    Bile-esculin agar has been used for several years for the presumptive identification of group D streptococci. All members of the Enterobacteriaceae family will also grow on this medium, but only certain ones can hydrolyze esculin to 6,7-dihydroxycoumarin, which reacts with iron to produce a characteristic blackening of the medium. One thousand and six cultures from clinical specimens representing 20 genera were isolated and identified. Heavy inocula from fresh pure culture isolates on heart infusion agar were placed on bile-esculin agar slants and incubated at 35 C. The slants were examined at 4 h and again at 18 h for esculin hydrolysis. Shigella, Salmonella, Arizona, Proteus mirabilis, Proteus morganii, Providencia alcalifaciens, and Providencia stuartii all produced negative results. Klebsiella pneumoniae, Enterobacter aerogenes, Serratia marcescens, and Serratia rubidaea produced a positive reaction in 4 h. The other remaining eight genera exhibited varying results. The use of this medium in conjunction with triple sugar iron-lysine iron agar has been of great value in differentiating the Klebsiella-Enterobacter-Serratia group from other Enterobacteriaceae. PMID:1176613

  12. Evaluation of an Automated Instrument for Inoculating and Spreading Samples onto Agar Plates.

    PubMed

    Glasson, J H; Guthrie, L H; Nielsen, D J; Bethell, F A

    2008-04-01

    The findings from a preliminary assessment of a new instrument designed for the inoculation and spreading of specimens for microbiological analysis onto agar plates are described. The study found that the instrument was able to select full or biplates from a number of input cassettes, each containing different agar types. Samples were then inoculated by the instrument onto the agar surfaces and spread by a novel plastic applicator. Following this, the instrument labeled the plates and sorted them into a number of specified output stations. It was found that the instrument was able to inoculate and spread samples over a greater proportion of the agar plate surface than the manual loop-to-plate method. As a consequence, up to 44% more usable colonies were produced per plate from clinical specimens and standard cultures. Viable counts showed that the instrument was able to detect as few as 10(2) CFU/ml in fluids and also facilitated the enumeration of organisms, particularly in specimens such as urine.

  13. Development of hyperspectral imaging technique for salmonella enteritidis and typhimurium on agar plates

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Salmonella is a common cause of foodborne disease resulting from the consumption of contaminated food products. Although a direct plating method is widely used for presumptive positive screening of pathogenic Salmonella colonies on agar plates, it is labor-intensive, time-consuming and also prone to...

  14. Analysis of beta-hemolysis in human blood agars by Streptococcus pyogenes.

    PubMed

    Zomorodian, Kamiar; Rahimi, Mohammad Javad; Safaei, Akbar; Bazargani, Abdollah; Motamadi, Marjan; Kharazi, Mahboobeh; Mostaghni, Setareh; Pakshir, Keyvan; Ghaedi, Hamid; Afsarian, Mohammad Hossein

    2011-06-01

    The aim of the study was to assess the reliability of human blood agar media (HuBA) in identifying Streptococcus pyogenes by hemolysis analysis. We analyze several factors that might affect the accuracy of HuBA media for microbial analysis, including incubation time, blood group, Rh factor and presence of antistreptolysin-o.

  15. Rapid diagnosis of acanthamoeba keratitis using non-nutrient agar with a lawn of E. coli

    PubMed Central

    2013-01-01

    Background A patient presented with a corneal foreign body in his only eye. He was treated with prophylactic antibiotics and sent home, but deteriorated. Findings He returned to the hospital 5 days later, and on slit-lamp examination, there was ciliary injection, corneal oedema and a 1 mm × 1 mm corneal abscess with mild anterior uveitis. Corneal scrapings were taken for culture on a non-nutrient agar with a lawn of Escherichia coli, on chocolate agar and on blood agar. He was treated with fortified gentamicin and cefazolin drops. He improved and was discharged 4 days after admission. On day 5, the culture results showed acanthamoeba. He was brought back to the hospital and treated with hourly chlorhexidine drops, ofloxacin six times daily and neomycin/dexamethasone drops once daily. On day 7, he was discharged to continue treatment at home, at which time his visual acuity in that eye was 6/9, and slit-lamp examination showed punctate keratitis and a stromal opacity with mild peripheral infiltration. Conclusions Culture on non-nutrient agar with a lawn of E. coli is a rapid, reliable and less invasive alternative to corneal biopsy for the diagnosis of acanthamoeba infection. We suggest using this method where acanthamoeba is suspected. Owing to the risk of corneal abscess, orthokeratology should be avoided in an amblyopic patient or an only eye. Acanthamoeba infection may be masked by other eye diseases. PMID:23514313

  16. Radiation survival of murine and human melanoma cells utilizing two assay systems: monolayer and soft agar.

    PubMed Central

    Yohem, K. H.; Slymen, D. J.; Bregman, M. D.; Meyskens, F. L.

    1988-01-01

    The radiation response of murine and human melanoma cells assayed in bilayer soft agar and monolayer was examined. Cells from the murine melanoma Cloudman S91 CCL 53.1 cell line and three human melanoma cell strains (C8146C, C8161, and R83-4) developed in our laboratory were irradiated by single dose X-rays and plated either in agar or on plastic. D0 values were the same within 95% confidence intervals for cells from the human melanoma cell strains C8146C, C8161, and R83-4 but were dissimilar for the murine cell line CCL 53.1 Dq values were different for all cells studied. The shape of the survival curve for all four melanomas was not identical for cells assayed in soft agar versus cells grown on plastic. This would indicate that apparent radiosensitivity was influenced by the method of assay although there were no apparent consistent differences between the curves generated by monolayer or bilayer soft agar assays. PMID:3348949

  17. In vitro growth of bioactive nanostructured apatites via agar-gelatin hybrid hydrogel.

    PubMed

    Deng, Yi; Zhao, Xianghui; Zhou, Yongsheng; Zhu, Peizhi; Zhang, Li; Wei, Shicheng

    2013-12-01

    Biomimetic synthesis of bone-like carbonated apatite with good biocompatibility is a promising strategy for the development of novel biomaterials for bone engineering applications. Most research efforts have been focused on only protein-based or only polysaccharide-based template for synthesis of apatite minerals. To understand the cooperative roles of gelatin and polysaccharide playing in the biomineralization, agar hydrogel, gelatin and agar-gelatin hybrid hydrogel were respectively introduced as mineralization matrix for the in vitro growth of apatite in the study. It was shown that bundle-like carbonated apatite was successfully prepared in agar-gelatin hybrid hydrogel for the first time, through the interaction between apatite and matrix macromolecule under physiological temperature. Moreover, the in vitro biocompatibility of the prepared nanostructured apatite crystals was investigated using CCK-8 assay and alkaline phosphatase activity of osteoblast-like MC3T3-E1. Compared with HA synthesized by traditional method, the obtained apatite in agar-gelatin hybrid hydrogel could provide significantly higher cell viability and alkaline phosphatase activity. Through the study, we could better understand the role of gelatin and polysaccharide in bone formation process, and the product is a promising candidate to be used in bone tissue engineering.

  18. Applying Agar's Concept of "Languaculture" to Explain Asian Students' Experiences in the Australian Tertiary Context

    ERIC Educational Resources Information Center

    Norris, Lindy; Tsedendamba, Nara

    2015-01-01

    This paper reports part of a broader qualitative case study of Asian students "translation" (Agar, 2006) to study in an Australian university. The paper is concerned with the experiences of eight participants and their involvement in a training programme in the use of language learning strategies (LLS) to support their engagement with…

  19. The relationship between growth in agar, karyotype and prognosis in acute leukaemia.

    PubMed

    Gustavsson, A; Mitelman, F; Olofsson, T; Olsson, I

    1984-04-01

    The growth pattern in agar culture and the karyotype of bone marrow cells were studied in 79 patients with untreated acute non-lymphocytic leukaemia (ANLL). Results were divided into the following groups: (A) colony and cluster formation; (B) growth of less than 600 small clusters per 10(5) cells; (C) growth of more than 600 small clusters; (D) no growth in agar. Cytogenetically, the patients were divided into 3 categories: NN, normal metaphases only; AN, both abnormal and normal metaphases and AA, abnormal metaphases only. An association was seen between growth pattern and karyotype: the majority of NN patients (33/37) belonged to group (A + B) while in group (C + D) 20/24 patients were AN or AA. 37 patients were prognostically evaluable. The growth pattern in agar but not the cytogenetic pattern had prognostic implications. 25 patients with acute lymphocytic leukaemia (ALL) were also studied at diagnosis. Different growth patterns in agar had no impact on prognosis. No relationship was detected between growth pattern and karyotype in ALL.

  20. Increased sensitivity of routine laboratory detection of Strongyloides stercoralis and hookworm by agar-plate culture.

    PubMed

    Jongwutiwes, S; Charoenkorn, M; Sitthichareonchai, P; Akaraborvorn, P; Putaporntip, C

    1999-01-01

    The efficacy of agar-plate culture has been evaluated for the detection of Strongyloides stercoralis and hookworm, compared with direct smear, the formalin-ether sedimentation technique and the filter-paper method. Of 1085 stool samples from the routine laboratory service at King Chulalongkorn Memorial Hospital in Bangkok, 241 samples harboured S. stercoralis, 153 hookworm and 2 Rhabditis hominis. The recovery rate of S. stercoralis by agar-plate culture is significantly superior to the other methods (P < 0.005). The ratios of positive results from the methods used to the total number of S. stercoralis-positive cases were as follows: 1:1.03 by agar-plate culture, 1:1.85 by the filter-paper method, 1:1.98 by the sedimentation technique and 1:10.48 by direct stool smear. A similar trend of the efficacy ratio of each method was obtained for hookworm detection. The characteristic furrows left by hookworm larvae, and larvae and adults of S. stercoralis could be used for preliminary species identification. Daily search for furrows on agar plates for up to 6 consecutive days resulted in an increased sensitivity for diagnosis of both S. stercoralis and hookworm infections.

  1. Use of bile-esculin agar for rapid differentiation of Enterobacteriaceae.

    PubMed

    Lindell, S S; Quinn, P

    1975-05-01

    Bile-esculin agar has been used for several years for the presumptive identification of group D streptococci. All members of the Enterobacteriaceae family will also grow on this medium, but only certain ones can hydrolyze esculin to 6,7-dihydroxycoumarin, which reacts with iron to produce a characteristic blackening of the medium. One thousand and six cultures from clinical specimens representing 20 genera were isolated and identified. Heavy inocula from fresh pure culture isolates on heart infusion agar were placed on bile-esculin agar slants and incubated at 35 C. The slants were examined at 4 h and again at 18 h for esculin hydrolysis. Shigella, Salmonella, Arizona, Proteus mirabilis, Proteus morganii, Providencia alcalifaciens, and Providencia stuartii all produced negative results. Klebsiella pneumoniae, Enterobacter aerogenes, Serratia marcescens, and Serratia rubidaea produced a positive reaction in 4 h. The other remaining eight genera exhibited varying results. The use of this medium in conjunction with triple sugar iron-lysine iron agar has been of great value in differentiating the Klebsiella-Enterobacter-Serratia group from other Enterobacteriaceae.

  2. Automated agar plate streaker: a linear plater on Society for Biomolecular Sciences standard plates.

    PubMed

    King, Gregory W; Kath, Gary S; Siciliano, Sal; Simpson, Neal; Masurekar, Prakash; Sigmund, Jan; Polishook, Jon; Skwish, Stephen; Bills, Gerald; Genilloud, Olga; Peláez, Fernando; Martín, Jesus; Dufresne, Claude

    2006-09-01

    Several protocols for bacterial isolation and techniques for aerobic plate counting rely on the use of a spiral plater to deposit concentration gradients of microbial suspensions onto a circular agar plate to isolate colony growth. The advantage of applying a gradient of concentrations across the agar surface is that the original microbiological sample can be applied at a single concentration rather than as multiple serial dilutions. The spiral plater gradually dilutes the sample across a compact area and therefore saves time preparing dilutions and multiple agar plates. Commercial spiral platers are not automated and require manual sample loading. Dispensing of the sample volume and rate of gradients are often very limited in range. Furthermore, the spiral sample application cannot be used with rectangular microplates. Another limitation of commercial spiral platers is that they are useful only for dilute, filtered suspensions and cannot plate suspensions of coarse organic particles therefore precluding the use of many kinds of microorganism-containing substrata. An automated agar plate spreader capable of processing 99 rectangular microplates in unattended mode is described. This novel instrument is capable of dispensing discrete volumes of sample in a linear pattern. It can be programmed to dispense a sample suspense at a uniform application rate or across a decreasing concentration gradient.

  3. Comparison of the antibacterial activity of chelating agents using the agar diffusion method

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The agar diffusion assay was used to examine antibacterial activity of 2 metal chelators. Concentrations of 0 to 40 mM of ethylenediaminetetraacetic acid (EDTA) and ethylenediamine-N,N’-disuccinic acid (EDDS) were prepared in 1.0 M potassium hydroxide (KOH). The pH of the solutions was adjusted to 1...

  4. Hyperspectral image reconstruction using RGB color for foodborne pathogen detection on agar plates

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This paper reports the latest development of a color vision technique for detecting colonies of foodborne pathogens grown on agar plates with a hyperspectral image classification model that was developed using full hyperspectral data. The hyperspectral classification model depended on reflectance sp...

  5. Hyperspectral image reconstruction using RGB color for foodborne pathogen detection on agar plates

    NASA Astrophysics Data System (ADS)

    Yoon, Seung-Chul; Shin, Tae-Sung; Park, Bosoon; Lawrence, Kurt C.; Heitschmidt, Gerald W.

    2014-03-01

    This paper reports the latest development of a color vision technique for detecting colonies of foodborne pathogens grown on agar plates with a hyperspectral image classification model that was developed using full hyperspectral data. The hyperspectral classification model depended on reflectance spectra measured in the visible and near-infrared spectral range from 400 and 1,000 nm (473 narrow spectral bands). Multivariate regression methods were used to estimate and predict hyperspectral data from RGB color values. The six representative non-O157 Shiga-toxin producing Eschetichia coli (STEC) serogroups (O26, O45, O103, O111, O121, and O145) were grown on Rainbow agar plates. A line-scan pushbroom hyperspectral image sensor was used to scan 36 agar plates grown with pure STEC colonies at each plate. The 36 hyperspectral images of the agar plates were divided in half to create training and test sets. The mean Rsquared value for hyperspectral image estimation was about 0.98 in the spectral range between 400 and 700 nm for linear, quadratic and cubic polynomial regression models and the detection accuracy of the hyperspectral image classification model with the principal component analysis and k-nearest neighbors for the test set was up to 92% (99% with the original hyperspectral images). Thus, the results of the study suggested that color-based detection may be viable as a multispectral imaging solution without much loss of prediction accuracy compared to hyperspectral imaging.

  6. Mercury in fruiting bodies of Fly Agaric Amanita muscaria (L.: Fr.) Pers. collected from Poland

    NASA Astrophysics Data System (ADS)

    Falandysz, J.; Lipka, K.

    2003-05-01

    Total mercury concentrations were determined in the fruiting bodies of Fly Agaric Amanita muscaria (L.: FL) Pers. and underlying soil substrate collected from several sites in Poland in 1993-2000 to evaluate mercury status as contaminant and bioindicating features of this species. The samples were collected from the spatially distant sites such as: Zaborski Landscape Park, Mierzeja Wiślana Landscape Park, Wdzydzki Landscape Park, Borecka Forest, Tucholskie Forest, Wieluńska Upland, the communities of Gubin, Manowo, Lubiana and Morag. Total mercury content of caps and stalks of Fly agaric varied widely depending on the sites examined. The range of the mean mercury concentrations for all 17 sites was between 96±10 and 1900±1400 ng/g dry wt for the caps and between 6l±32 and 920±760 ng/g dry wt for the stalks, while between 4.4±3.1 and 150±20 ng/g were noted for soil substrate samples from 9 sites examined. Fly agaric independently of the site examined showed relatively good capacity to accumulate total mercury and BCF values varied between 16±10 and 74±15 for the caps and between 11±8 and 42±10 for the stalks. Nevertheless, relatively high bioconcentration potential of mercury by Fly agaric seems to be specific for that species and under soil mercury concentrations noted no bioindication properties of this mushroom could be observed.

  7. Use of the Soft-agar Overlay Technique to Screen for Bacterially Produced Inhibitory Compounds.

    PubMed

    Hockett, Kevin L; Baltrus, David A

    2017-01-14

    The soft-agar overlay technique was originally developed over 70 years ago and has been widely used in several areas of microbiological research, including work with bacteriophages and bacteriocins, proteinaceous antibacterial agents. This approach is relatively inexpensive, with minimal resource requirements. This technique consists of spotting supernatant from a donor strain (potentially harboring a toxic compound(s)) onto a solidified soft agar overlay that is seeded with a bacterial test strain (potentially sensitive to the toxic compound(s)). We utilized this technique to screen a library of Pseudomonas syringae strains for intraspecific killing. By combining this approach with a precipitation step and targeted gene deletions, multiple toxic compounds produced by the same strain can be differentiated. The two antagonistic agents commonly recovered using this technique are bacteriophages and bacteriocins. These two agents can be differentiated using two simple additional tests. Performing a serial dilution on a supernatant containing bacteriophage will result in individual plaques becoming less in number with greater dilution, whereas serial dilution of a supernatant containing bacteriocin will result a clearing zone that becomes uniformly more turbid with greater dilution. Additionally, a bacteriophage will produce a clearing zone when spotted onto a fresh soft agar overlay seeded with the same strain, whereas a bacteriocin will not produce a clearing zone when transferred to a fresh soft agar lawn, owing to the dilution of the bacteriocin.

  8. Agar media that indicate acid production from sorbitol by oral microorganisms.

    PubMed Central

    Kalfas, S; Edwardsson, S

    1985-01-01

    Two varieties of agar medium (Trypticase [BBL Microbiology Systems]-serum-sorbitol-bromcresol purple agar [TSSB] and Trypticase-blood-sorbitol-CaCO3 agar [TBSCa]) indicating microbial acid production from sorbitol were tested. The media were devised for use in studies on the prevalence of sorbitol-fermenting human oral microorganisms incubated in an anaerobic or microaerophilic atmosphere containing 5 to 6% CO2. TSSB contains bromcresol purple as the pH indicator and NaHCO3 as the main buffering salt. TBSCa contains CaCO3 as both the buffering salt and the indicator of acid production. The growth yield of pure cultures of oral microorganisms on TBSCa was shown to equal that on blood agar incubated under similar conditions. TSSB inhibited the growth of several bacteria to various extents. The recovery of sorbitol-fermenting microorganisms from oral specimens was the greatest when the specimens were assayed with TBSCa. The poorer results obtained with TSSB were mainly due to the decoloration of the pH indicator in this medium and the presence of greater numbers of sorbitol false-positive colonies. Images PMID:2933424

  9. Micro-agar salt bridge in patch-clamp electrode holder stabilizes electrode potentials

    PubMed Central

    Shao, Xuesi M.; Feldman, Jack L.

    2015-01-01

    Maintaining a stable electrode potential is critical for patch-clamp measurements. The electrode potential of conventional patch electrode-holder assembly, where an Ag/AgCl wire is in direct contact with the patch pipette filling solution, is subject to drift if the pipette solution contains a low concentration of chloride ions (Cl−). We developed an agar bridge of 3 M KCl filled in a polyimide microtubing which forms an electrical connection between an Ag/AgCl wire and the pipette solution. We examined the offset potentials of the micro-agar salt bridge electrode assembly in parallel with a conventional electrode assembly in generic recording conditions (the pipette solution contained 5 mM NaCl). The junction potential between the Ag/AgCl wire and the pipette filling solution in the conventional electrode contributed to most of the offset potential drift observed during the course of 30 min recordings. The drift was up to 27.3 mV after several changes of the glass pipette. In contrast, the micro-agar salt bridge stabilized the electrode potential within typically 2 mV without affecting the patch electrode resistance, capacitance or noise level. Numerical simulations showed that Cl− diffusion from the agar bridge to the tip caused a negligible 0.4 μM Cl− concentration change at the pipette tip within 30 min. This method is easy to implement and provides long-term recording stability. The micro-agar salt bridge can fit in most commercial patch electrode holders and can be conveniently maintained. PMID:16916545

  10. Performance of chromID Clostridium difficile agar compared with BBL C. difficile selective agar for detection of C. difficile in stool specimens.

    PubMed

    Han, Sang Bong; Chang, Jiyoung; Shin, Sang Hyun; Park, Kang Gyun; Lee, Gun Dong; Park, Yong Gyu; Park, Yeon-Joon

    2014-09-01

    We evaluated the performance of a new chromogenic medium for detection of Clostridium difficile, chromID C. difficile agar (CDIF; bioMérieux, France), by comparison with BBL C. difficile Selective Agar (CDSA; Becton Dickinson and Company, USA). After heat pre-treatment (80℃, 5 min), 185 diarrheal stool samples were inoculated onto the two media types and incubated anaerobically for 24 hr and 48 hr for CDIF and for 48 hr and 72 hr for CDSA. All typical colonies on each medium were examined by Gram staining, and the gram-positive rods confirmed to contain the tpi gene by PCR were identified as C. difficile. C. difficile was recovered from 36 samples by using a combination of the two media. The sensitivity with CDIF 48 hr was highest (100%) and was significantly higher than that with CDIF 24 hr (58.3%; P<0.001), because samples with a low burden of C. difficile tended to require prolonged incubation up to 48 hr (P<0.001). The specificity of CDIF 24 hr and CDIF 48 hr (99.3% and 90.6%, respectively) was significantly higher than that of CDSA 48 hr and CDSA 72 hr (72.5% and 67.1%, respectively; P<0.001). CDIF was effective for detecting C. difficile in heat-pretreated stool specimens, thus reducing unnecessary testing for toxin production in non-C. difficile isolates and turnaround time.

  11. Differentiating non-0157:H7 STEC serogroups from ground beef plated on agar media by hyperspetral imaging

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Introduction: The development of an assay to detect and confirm a positive non-O157:H7 isolate is challenging when mixed morphologically results are obtained from the serogroups growing on Rainbow agar. Rainbow agar is only claimed by the manufacturer to be very specific for E.coli O157:H7 strain...

  12. Effect of lignin on water vapor barrier, mechanical, and structural properties of agar/lignin composite films.

    PubMed

    Shankar, Shiv; Reddy, Jeevan Prasad; Rhim, Jong-Whan

    2015-11-01

    Biodegradable composite films were prepared using two renewable resources based biopolymers, agar and lignin alkali. The lignin was used as a reinforcing material and agar as a biopolymer matrix. The effect of lignin concentration (1, 3, 5, and 10wt%) on the performance of the composite films was studied. In addition, the mechanical, water vapor barrier, UV light barrier properties, FE-SEM, and TGA of the films were analyzed. The agar/lignin films exhibited higher mechanical and UV barrier properties along with lower water vapor permeability compared to the neat agar film. The FTIR and SEM results showed the compatibility of lignin with agar polymer. The swelling ratio and moisture content of agar/lignin composite films were decreased with increase in lignin content. The thermostability and char content of agar/lignin composite films increased with increased lignin content. The results suggested that agar/lignin films have a potential to be used as a UV barrier food packaging material for maintaining food safety and extending the shelf-life of the packaged food.

  13. Agar Sediment Test for Assessing the Suitability of Organic Waste Streams for Recovering Nutrients by the Aquatic Worm Lumbriculus variegatus

    PubMed Central

    Laarhoven, Bob; Elissen, H. J. H.; Temmink, H.; Buisman, C. J. N.

    2016-01-01

    An agar sediment test was developed to evaluate the suitability of organic waste streams from the food industry for recovering nutrients by the aquatic worm Lumbriculus variegatus (Lv). The effects of agar gel, sand, and food quantities in the sediment test on worm growth, reproduction, and water quality were studied. Agar gel addition ameliorated growth conditions by reducing food hydrolysis and altering sediment structure. Best results for combined reproduction and growth were obtained with 0.6% agar-gel (20 ml), 10 g. fine sand, 40 g. coarse sand, and 105 mg fish food (Tetramin). With agar gel, ingestion and growth is more the result of addition of food in its original quality. Final tests with secondary potato starch sludge and wheat bran demonstrated that this test is appropriate for the comparison of solid feedstuffs and suspended organic waste streams. This test method is expected to be suitable for organic waste studies using other sediment dwelling invertebrates. PMID:26937632

  14. Agar Sediment Test for Assessing the Suitability of Organic Waste Streams for Recovering Nutrients by the Aquatic Worm Lumbriculus variegatus.

    PubMed

    Laarhoven, Bob; Elissen, H J H; Temmink, H; Buisman, C J N

    2016-01-01

    An agar sediment test was developed to evaluate the suitability of organic waste streams from the food industry for recovering nutrients by the aquatic worm Lumbriculus variegatus (Lv). The effects of agar gel, sand, and food quantities in the sediment test on worm growth, reproduction, and water quality were studied. Agar gel addition ameliorated growth conditions by reducing food hydrolysis and altering sediment structure. Best results for combined reproduction and growth were obtained with 0.6% agar-gel (20 ml), 10 g. fine sand, 40 g. coarse sand, and 105 mg fish food (Tetramin). With agar gel, ingestion and growth is more the result of addition of food in its original quality. Final tests with secondary potato starch sludge and wheat bran demonstrated that this test is appropriate for the comparison of solid feedstuffs and suspended organic waste streams. This test method is expected to be suitable for organic waste studies using other sediment dwelling invertebrates.

  15. Agar plate freezing assay for the in situ selection of transformed ice nucleating bacteria.

    PubMed

    Anastassopoulos, Elias

    2006-10-01

    An agar plate freezing assay is described based on the incorporation of fluorescein dye in agar medium. Upon addition of fluorescein the medium becomes transparent. This facilitates the monitoring of the ice nucleation event in vivo and the subsequent in situ selection of transformed ice nucleating bacteria. In comparison with known assays for the screening of transformants, the proposed assay is very accurate and reproducible. It may be applied in environmental samples screening for ice nucleating organisms, or in cDNA or genomic libraries for identifying novel ice nucleation genes. It may also prove useful in comparative studies of the ice nucleation activity, e.g. in directed evolution experiments involving ice nucleation genes.

  16. Crystallization of brushite from EDTA-chelated calcium in agar gels

    NASA Astrophysics Data System (ADS)

    Plovnick, Ross H.

    1991-10-01

    Brushite (dicalcium phosphate dihydrate, CaHPO 4·2H 2O, DCPD) has been crystallized from ethylenediaminetetraacetic acid (EDTA)-chelated calcium in agar gels at initial pH 4.5-6.4 and Ca/P molar ratio above about 0.8. White, spherular crystalline DCPD aggregates up to 1 mm in diameter grew in 8-10 weeks. Liesegang ring were occassionally observed at initial gel pH 5 and Ca/P molar ratio near 1. Crystals were characterized by X-ray diffraction analysis, scanning electron microscopy, and infrared absorption spectroscopy. Brushite crystals were also grown in agar gels with either unchelated Ca initially present in the gels and EDTA in overlying solutions, or EDTA initially present in the gels and unchelated Ca in overlying solutions. These crystals grew as 2-3 mm aggregates mainly within 1-3 cm of the gel-solution interface.

  17. [Physical properties of the agar of Gracilariopsis tenuifrons (Gracilariacea) from Sucre, Venezuela].

    PubMed

    Zecchinel, E; Brito, L; Lárez, G

    2000-12-01

    The yield, gel strength, gelling and melting temperatures of Gracilariopsis tenuifrons agar from Guayacán, Araya Peninsula, Sucre State, Venezuela were determined. Yield values with and without alkali treatment ranged from 23.22 to 39.57% and from 16.29 to 22.42% respectively, while gel strength with alkali treatment fluctuated betwen 699.31 and 1231.69 g/cm2 and without treatment varied from 278.0 to 691.06 g/cm2. Gelling and melting temperatures were in the range reported for other agarophytes. Considering gel strength, the agar quality of G. tenuifrons was higher than in other species and its exploitation in economically feasible.

  18. Modification of the Congo red agar method to detect biofilm production by Staphylococcus epidermidis.

    PubMed

    Kaiser, Thaís Dias Lemos; Pereira, Eliezer Menezes; Dos Santos, Kátia Regina Netto; Maciel, Ethel Leonor Noia; Schuenck, Ricardo Pinto; Nunes, Ana Paula Ferreira

    2013-03-01

    Staphylococcus epidermidis in immunocompromised patients can cause bacteremia related to the use of catheter due to biofilm production. There are different phenotypic methods to detect biofilm formation. One method is based on culture in brain heart infusion agar (BHIA) containing sucrose and red Congo dye (original Congo red agar). Our group created a new CRA formula and we have confirmed its capacity to detect biofilm production in 210 S. epidermidis strains, including 76 (36.2%) icaAB gene-positive strains. Other parameters were also evaluated. The new CRA formula that gave the best results was BHIA with sucrose (5%), Congo red (0.08%), NaCl (1.5%), glucose (2%), and vancomycin (0.5 mg/mL) (vancomycin-modified CRA-CRAmod). The CRAmod plus vancomycin may be a promising tool and can help to determine the real participation of S. epidermidis in the infectious process.

  19. Tentative inhibition zone criteria (Bauer-Kirby agar disk diffusion method) for rifampin against staphylococci.

    PubMed

    Traub, W H; Spohr, M; Bauer, D

    1987-01-01

    Two of 359 (0.6%) clinical isolates of Staphylococcus aureus and 12 of 218 (5.5%) clinical isolates of coagulase-negative staphylococci were resistant or of intermediate susceptibility against rifampin as based on minimal inhibitory concentration (MIC) breakpoints obtained with the agar dilution method: MIC greater than or equal to 2 micrograms/ml = resistant; MIC 0.25-1 microgram/ml = intermediate susceptible; MIC less than 0.125 microgram/ml = susceptible. The following inhibition zone criteria with 2 micrograms rifampin disks were proposed for staphylococcal isolates utilizing the Bauer-Kirby agar disk diffusion test: diameter of inhibition zones less than or equal to 13 mm = resistant; diameter 14-21 mm = intermediate susceptible; diameter greater than or equal to 22 mm = susceptible.

  20. Enhancing Bioaerosol Sampling by Andersen Impactors Using Mineral-Oil-Spread Agar Plate

    PubMed Central

    Xu, Zhenqiang; Wei, Kai; Wu, Yan; Shen, Fangxia; Chen, Qi; Li, Mingzhen; Yao, Maosheng

    2013-01-01

    As a bioaerosol sampling standard, Andersen type impactor is widely used since its invention in 1950s, including the investigation of the anthrax attacks in the United States in 2001. However, its related problems such as impaction and desiccation stress as well as particle bounce have not been solved. Here, we improved its biological collection efficiencies by plating a mineral oil layer (100 µL) onto the agar plate. An Andersen six-stage sampler and a BioStage impactor were tested with mineral-oil-spread agar plates in collecting indoor and outdoor bacterial and fungal aerosols. The effects of sampling times (5, 10 and 20 min) were also studied using the BioStage impactor when sampling environmental bioaerosols as well as aerosolized Bacillus subtilis (G+) and Escherichia coli (G-). In addition, particle bounce reduction by mineral-oil-plate was also investigated using an optical particle counter (OPC). Experimental results revealed that use of mineral-oil-spread agar plate can substantially enhance culturable bioaerosol recoveries by Andersen type impactors (p-values<0.05). The recovery enhancement was shown to depend on bioaerosol size, type, sampling time and environment. In general, more enhancements (extra 20%) were observed for last stage of the Andersen six-stage samplers compared to the BioStage impactor for 10 min sampling. When sampling aerosolized B. subtilis, E. coli and environmental aerosols, the enhancement was shown to increase with increasing sampling time, ranging from 50% increase at 5 min to ∼100% at 20 min. OPC results indicated that use of mineral oil can effectively reduce the particle bounce with an average of 66% for 10 min sampling. Our work suggests that enhancements for fungal aerosols were primarily attributed to the reduced impaction stress, while for bacterial aerosols reduced impaction, desiccation and particle bounce played major roles. The developed technology can readily enhance the agar-based techniques including those high

  1. The Resazurin-Agar Method - a Quick Test to Determine Water Quality

    NASA Astrophysics Data System (ADS)

    Huckfeldt, J.; Westphal, B.; Claußen, L.

    2015-12-01

    Rezasurin has been used as a smart tracer in stream ecosystems to indicate metabolic activity, specifically aerobic respiration by heterotrophic bacteria. Resazurin is a blue compound which is irreversibly reduced to the pink resorufin in the presence of aerobic bacteria. The degree and speed of colour change from blue to pink is a measure of the degree of oxygen consumption and thus an indirect indication of the concentration of aerobic bacteria in a given medium. A high concentration of bacteria in water indicates a bad water quality. In our work a method was developed using resazurin agar plates to find a quick and easy way for testing water quality and comparing concentrations of bacteria in freshwater and seawater samples. The theory was to concentrate bacteria from a defined volume of water sample onto polycarbonate filters (0.2 μm), which are then placed onto the resazurin agar plate. The presence of aerobic bacteria on the filter will reduce the resazurin in the agar and the compound changes its colour. First tests conducted with different dilutions of a pure culture of yoghurt bacteria showed promising results and confirmed the feasibility of the method. In a further assay, we used water samples from different water layers and different temperatures and were also able to observe differences in the concentration of bacteria, depending on these different environmental conditions.The assay was also successfully used with seawater samples, collected from 2 different stations at 3 different depths in the Baltic Sea (salinity=15). The discolouration of the plates showed good correlation with the oxygen concentrations in the water. The resazurin-agar plate method is economical and fast. Several samples could be investigated at the same time without sacrificing the reliability of the results. Thus it is a good pre-screening test for a quantitative evaluation of bacteria in a water sample.

  2. Rapid Isolation and Susceptibility Testing of Leptospira spp. Using a New Solid Medium, LVW Agar

    PubMed Central

    Wuthiekanun, Vanaporn; Amornchai, Premjit; Paris, Daniel H.; Langla, Sayan; Thaipadunpanit, Janjira; Chierakul, Wirongrong; Smythe, Lee D.; White, Nicholas J.; Day, Nicholas P. J.; Peacock, Sharon J.

    2013-01-01

    Pathogenic Leptospira spp., the causative agents of leptospirosis, are slow-growing Gram-negative spirochetes. Isolation of Leptospira from clinical samples and testing of antimicrobial susceptibility are difficult and time-consuming. Here, we describe the development of a new solid medium that facilitates more-rapid growth of Leptospira spp. and the use of this medium to evaluate the Etest's performance in determining antimicrobial MICs to drugs in common use for leptospirosis. The medium was developed by evaluating the effects of numerous factors on the growth rate of Leptospira interrogans strain NR-20157. These included the type of base agar, the concentration of rabbit serum (RS), and the concentration and duration of CO2 incubation during the initial period of culture. The highest growth rate of NR-20157 was achieved using a Noble agar base supplemented with 10% RS (named LVW agar), with an initial incubation at 30°C in 5% CO2 for 2 days prior to continuous culture in air at 30°C. These conditions were used to develop the Etest for three species, L. interrogans (NR-20161), L. kirschnerii (NR-20327), and L. borgpetersenii (NR-20151). The MICs were read on day 7 for all samples. The Etest was then performed on 109 isolates of pathogenic Leptospira spp. The MIC90 values for penicillin G, doxycycline, cefotaxime, ceftriaxone, and chloramphenicol were 0.64 units/ml and 0.19, 0.047, 0.5, and 2 μg/ml, respectively. The use of LVW agar, which enables rapid growth, isolation of single colonies, and simple antimicrobial susceptibility testing for Leptospira spp., provides an opportunity for new areas of fundamental and applied research. PMID:23114772

  3. Draft genome of agar-degrading marine bacterium Gilvimarinus agarilyticus JEA5.

    PubMed

    Lee, Youngdeuk; Lee, Su-Jin; Park, Gun-Hoo; Heo, Soo-Jin; Umasuthan, Navaneethaiyer; Kang, Do-Hyung; Oh, Chulhong

    2015-06-01

    Gilvimarinus agarilyticus JEA5, which effectively degrades agar, was isolated from the seawater of Jeju Island, Republic of Korea. Here, we report the draft genome sequence of G. agarilyticus JEA5 with a total genome size of 4,179,438bp from 2 scaffolds (21 contigs) with 53.15% G+C content. Various polysaccharidases including 11 predicted agarases were observed from the draft genome of G. agarilyticus JEA5.

  4. Enhancing bioaerosol sampling by Andersen impactors using mineral-oil-spread agar plate.

    PubMed

    Xu, Zhenqiang; Wei, Kai; Wu, Yan; Shen, Fangxia; Chen, Qi; Li, Mingzhen; Yao, Maosheng

    2013-01-01

    As a bioaerosol sampling standard, Andersen type impactor is widely used since its invention in 1950s, including the investigation of the anthrax attacks in the United States in 2001. However, its related problems such as impaction and desiccation stress as well as particle bounce have not been solved. Here, we improved its biological collection efficiencies by plating a mineral oil layer (100 µL) onto the agar plate. An Andersen six-stage sampler and a BioStage impactor were tested with mineral-oil-spread agar plates in collecting indoor and outdoor bacterial and fungal aerosols. The effects of sampling times (5, 10 and 20 min) were also studied using the BioStage impactor when sampling environmental bioaerosols as well as aerosolized Bacillus subtilis (G+) and Escherichia coli (G-). In addition, particle bounce reduction by mineral-oil-plate was also investigated using an optical particle counter (OPC). Experimental results revealed that use of mineral-oil-spread agar plate can substantially enhance culturable bioaerosol recoveries by Andersen type impactors (p-values<0.05). The recovery enhancement was shown to depend on bioaerosol size, type, sampling time and environment. In general, more enhancements (extra 20%) were observed for last stage of the Andersen six-stage samplers compared to the BioStage impactor for 10 min sampling. When sampling aerosolized B. subtilis, E. coli and environmental aerosols, the enhancement was shown to increase with increasing sampling time, ranging from 50% increase at 5 min to ∼100% at 20 min. OPC results indicated that use of mineral oil can effectively reduce the particle bounce with an average of 66% for 10 min sampling. Our work suggests that enhancements for fungal aerosols were primarily attributed to the reduced impaction stress, while for bacterial aerosols reduced impaction, desiccation and particle bounce played major roles. The developed technology can readily enhance the agar-based techniques including those high

  5. How do microorganisms influence trace element uptake by plants? Screening in an agar model rhizosphere.

    NASA Astrophysics Data System (ADS)

    Marchetti, M.; Robinson, B. H.; Evangelou, M. W. H.; Vachey, A.; Schwitzguebel, J. P.; Bernier-Latmani, R.; Schulin, R.

    2009-04-01

    Trace elements (TE) are essential for humans and plants, but they may be toxic if their concentration is too high. For this reason, the management of TE in soils is very important. In some cases it may be necessary to increase the uptake of nutrients or TE by plants, for example in a biofortification perspective. Conversely, in some other cases TE uptake by plants should be decreased, for instance to avoid heavy metals entering the food chain via edible crops. Microorganisms living in the rhizosphere affect trace element (TE) uptake by plants. However, due to the complexity of this space and the variety of microorganisms that occur there, it is difficult to isolate the effect of any particular strain. To overcome this hurdle, we developed a system in which we grew plants under sterile conditions in agar and inoculated their rhizosphere with a single, well-defined microbial strain. For many years, agar has been used as a growth substrate for microorganisms and plant tissues. It is cheap, easy to use, and can be autoclaved to ensure its sterility. Because of its widespread use, an experiment conducted using this substrate can be reproduced under the same conditions in any laboratory. In contrast to soil, there is little interaction between the trace elements and the agar matrix. There are many studies investigating the influence of microorganisms on TE uptake by plants. However, so far only a small variety of microorganisms has been tested on few plant species. Therefore, the first objective of our research was to develop a method to rapidly screen a large variety of microorganisms on various plant species. Once this goal was achieved, we sought to study the effect of single, well-defined microbial strains on TE uptake by sunflower and wheat. The substrate for plants growth was a 10% agar solution prepared with modified Hoagland's solution and a TE solution containing 1 mg/kg Pb and molar equivalents of Cu, Ni and Zn. The agar solution was autoclaved and poured into

  6. Selection of brain metastasis-initiating breast cancer cells determined by growth on hard agar.

    PubMed

    Guo, Lixia; Fan, Dominic; Zhang, Fahao; Price, Janet E; Lee, Ju-Seog; Marchetti, Dario; Fidler, Isaiah J; Langley, Robert R

    2011-05-01

    An approach that facilitates rapid isolation and characterization of tumor cells with enhanced metastatic potential is highly desirable. Here, we demonstrate that plating GI-101A human breast cancer cells on hard (0.9%) agar selects for the subpopulation of metastasis-initiating cells. The agar-selected cells, designated GI-AGR, were homogeneous for CD44(+) and CD133(+) and five times more invasive than the parental GI-101A cells. Moreover, mice injected with GI-AGR cells had significantly more experimental brain metastases and shorter overall survival than did mice injected with GI-101A cells. Comparative gene expression analysis revealed that GI-AGR cells were markedly distinct from the parental cells but shared an overlapping pattern of gene expression with the GI-101A subline GI-BRN, which was generated by repeated in vivo recycling of GI-101A cells in an experimental brain metastasis model. Data mining on 216 genes shared between GI-AGR and GI-BRN breast cancer cells suggested that the molecular phenotype of these cells is consistent with that of cancer stem cells and the aggressive basal subtype of breast cancer. Collectively, these results demonstrate that analysis of cell growth in a hard agar assay is a powerful tool for selecting metastasis-initiating cells in a heterogeneous population of breast cancer cells, and that such selected cells have properties similar to those of tumor cells that are selected based on their potential to form metastases in mice.

  7. Ultrasound induced bubble clusters and tunnels in tissue-mimicking agar phantoms

    NASA Astrophysics Data System (ADS)

    Movahed, Pooya; Kreider, Wayne; Maxwell, Adam D.; Bailey, Michael R.; Freund, Jonathan B.

    2016-11-01

    Soft tissue fractionation induced by acoustic cavitation is desired for non-invasive tissue removal in histotripsy, while being a potential injury mechanism in other therapeutic ultrasound treatments such as lithotripsy. In this work, we investigate the formation of bubble clusters and tunnels in tissue-mimicking agar phantoms by focused ultrasound bursts to inform a class of damage models. Agar phantoms of different stiffness were subjected to a series of multi-cycle ultrasound bursts, using a burst wave lithotripsy (BWL) protocol, and simultaneously imaged at 200 frames per second (1 image per ultrasound burst). Some bubbles become visible in images ( 200 microns) due to the negative pressure ( 7.5 MPa) in the initial bursts, and the number of visible bubbles increases continuously during the subsequent bursts. A Rayleigh-Plesset-type bubble dynamics model, which accounts for viscoelastic confinement of agar gels, is developed. Material fatigue leading to eventual irreversible fracture-like failure in this model is proposed to explain the key observations. In addition to isolated, approximately spherical bubbles, long tunnel-like features are observed, which are seemingly lines of joined bubbles along a possible fracture or defect. The geometry of these tunnel-like features is quantified, and a physical explanation for tunnel formation is proposed in terms of bubble expansion and unstable collapse. This work was supported by NIH NIDDK Grant P01-DK043881.

  8. A supplemented soft agar chemotaxis assay demonstrates the Helicobacter pylori chemotactic response to zinc and nickel

    PubMed Central

    Sanders, Lisa; Andermann, Tessa M.

    2013-01-01

    Directed motility, or chemotaxis, is required for Helicobacter pylori to establish infection in the stomach, although the full repertoire of this bacterium’s chemotactic responses is not yet known. Here we report that H. pylori responds to zinc as an attractant and nickel as a repellent. To reach this conclusion, we employed both a temporal chemotaxis assay based on bacterial reversals and a supplemented soft agar spatial assay. We refined the temporal assay using a previously described chemorepellent, acid, and found that H. pylori requires rich media with serum to maintain optimal swimming motility. Surprisingly, we found that some strains respond to acid as an attractant, and that the TlpC chemoreceptor correlated with whether acid was sensed as an attractant or repellent. Using this same assay, we detected weak repellent responses to nickel and copper, and a varied response to zinc. We thus developed an alternative spatial chemotactic assay called the supplemented soft agar assay, which utilizes soft agar medium supplemented with the test compound. With Escherichia coli, the attractant serine slowed overall bacterial migration, while the repellent nickel increased the speed of overall migration. In H. pylori we detected slowed migration with doubled tryptone media, as well as zinc, consistent with an attractant response. In contrast, nickel increased migration, consistent with repulsion. PMID:23139399

  9. Pig and Goat Blood as Substitutes for Sheep Blood in Blood-Supplemented Agar Media

    PubMed Central

    Anand, Chandar; Gordon, Rhonda; Shaw, Helene; Fonseca, Kevin; Olsen, Merle

    2000-01-01

    In many developing countries sheep and horse blood, the recommended blood supplements in bacteriological media, are not readily available, whereas pig and goat blood are. Therefore, this study examined the use of pig and goat blood as potential substitutes for sheep blood in blood-supplemented bacteriologic media commonly used in clinical microbiology laboratories. In general, the growth characteristics and colony morphologies of a wide range of aerobic and anaerobic bacteria and Candida albicans were similar on media containing pig, goat, and sheep blood, although differences were found. Enterococcus sp. uniformly produced alpha-hemolysis when incubated in CO2, but in anaerobic conditions the hemolysis varied. In contrast, beta-hemolytic streptococci produced identical hemolytic reactions on all three media. Synergistic hemolysis was not observed on pig blood agar in the CAMP test nor on goat blood agar in the reverse CAMP test. The preparation of chocolate agar (heated) with pig blood required heating to a higher temperature than with sheep or goat blood to yield suitable growth of Haemophilus species. In general, we conclude that pig and goat blood are suitable alternatives to sheep blood for use in bacteriological media in settings where sheep and horse blood are not readily available. PMID:10655351

  10. Predicting the growth situation of Pseudomonas aeruginosa on agar plates and meat stuffs using gas sensors

    NASA Astrophysics Data System (ADS)

    Gu, Xinzhe; Sun, Ye; Tu, Kang; Dong, Qingli; Pan, Leiqing

    2016-12-01

    A rapid method of predicting the growing situation of Pseudomonas aeruginosa is presented. Gas sensors were used to acquire volatile compounds generated by P. aeruginosa on agar plates and meat stuffs. Then, optimal sensors were selected to simulate P. aeruginosa growth using modified Logistic and Gompertz equations by odor changes. The results showed that the responses of S8 or S10 yielded high coefficients of determination (R2) of 0.89–0.99 and low root mean square errors (RMSE) of 0.06–0.17 for P. aeruginosa growth, fitting the models on the agar plate. The responses of S9, S4 and the first principal component of 10 sensors fit well with the growth of P. aeruginosa inoculated in meat stored at 4 °C and 20 °C, with R2 of 0.73–0.96 and RMSE of 0.25–1.38. The correlation coefficients between the fitting models, as measured by electronic nose responses, and the colony counts of P. aeruginosa were high, ranging from 0.882 to 0.996 for both plate and meat samples. Also, gas chromatography–mass spectrometry results indicated the presence of specific volatiles of P. aeruginosa on agar plates. This work demonstrated an acceptable feasibility of using gas sensors—a rapid, easy and nondestructive method for predicting P. aeruginosa growth.

  11. An Agar-Based Method for Plating Marine Protozoan Parasites of the Genus Perkinsus

    PubMed Central

    Cold, Emma R.; Freyria, Nastasia J.; Martínez Martínez, Joaquín; Fernández Robledo, José A.

    2016-01-01

    The genus Perkinsus includes protozoan parasites of mollusks responsible for losses in the aquaculture industry and hampering the recovery of natural shellfish beds worldwide, and they are a key taxon for understanding intracellular parasitism adaptations. The ability to propagate the parasite in liquid media, in the absence of the host, has been crucial for improving understanding of its biology; however, alternative techniques to grow the parasite are needed to explore other basic aspects of the Perkinsus spp. biology. We optimized a DME: Ham’s F12–5% FBS- containing solid agar medium for plating Perkinsus marinus. This solid medium supported trophozoite propagation both by binary fission and schizogony. Colonies were visible to the naked eye 17 days after plating. We tested the suitability of this method for several applications, including the following: 1) Subcloning P. marinus isolates: single discrete P. marinus colonies were obtained from DME: Ham’s F12–5% FBS– 0.75% agar plates, which could be further propagated in liquid medium; 2) Subcloning engineered Perkinsus mediterraneus MOE[MOE]: GFP by streaking cultures on plates; 3) Chemical susceptibility: Infusing the DME: Ham’s F12–5% FBS– 0.75% agar plates with triclosan resulted in inhibition of the parasite propagation in a dose-dependent manner. Altogether, our plating method has the potential for becoming a key tool for investigating diverse aspects of Perkinsus spp. biology, developing new molecular tools, and for biotechnological applications. PMID:27149378

  12. The use of agar as a novel filler for monolithic matrices produced using hot melt extrusion.

    PubMed

    Lyons, John G; Devine, Declan M; Kennedy, James E; Geever, Luke M; O'Sullivan, Patrick; Higginbotham, Clement L

    2006-08-01

    The use of filler materials in an extended release monolithic polymer matrix can lead to a vastly altered release profile for the active pharmaceutical ingredient. A range of excipients for use in monolithic matrices have been discussed in the literature. The body of work described in this research paper outlines the use of agar as a novel filler material in a hot melt extruded polymer matrix. Several batches of matrix material were prepared with Diclofenac sodium used as the active pharmaceutical ingredient (API). Agar and microcrystalline cellulose were used as the filler materials in varying ratios, to examine the effect of % filler content as well as filler type on the properties of the hot melt extruded matrix. The resultant extrudates were characterised using steady state parallel plate rheometry, differential scanning calorimetry (DSC) and dissolution testing. The rheometry analysis concluded that the fillers used resulted in an increase in the matrix viscosity. The DSC scans obtained showed negligible effects on the melting behavior of the matrix as a result of the filler inclusion. Dissolution analysis showed that the presence of the fillers resulted in a slower release rate of API than for the matrix alone. The results detailed within this paper indicate that agar is a viable filler for extended release hot melt produced dosage forms.

  13. Pig and goat blood as substitutes for sheep blood in blood-supplemented agar media.

    PubMed

    Anand, C; Gordon, R; Shaw, H; Fonseca, K; Olsen, M

    2000-02-01

    In many developing countries sheep and horse blood, the recommended blood supplements in bacteriological media, are not readily available, whereas pig and goat blood are. Therefore, this study examined the use of pig and goat blood as potential substitutes for sheep blood in blood-supplemented bacteriologic media commonly used in clinical microbiology laboratories. In general, the growth characteristics and colony morphologies of a wide range of aerobic and anaerobic bacteria and Candida albicans were similar on media containing pig, goat, and sheep blood, although differences were found. Enterococcus sp. uniformly produced alpha-hemolysis when incubated in CO(2), but in anaerobic conditions the hemolysis varied. In contrast, beta-hemolytic streptococci produced identical hemolytic reactions on all three media. Synergistic hemolysis was not observed on pig blood agar in the CAMP test nor on goat blood agar in the reverse CAMP test. The preparation of chocolate agar (heated) with pig blood required heating to a higher temperature than with sheep or goat blood to yield suitable growth of Haemophilus species. In general, we conclude that pig and goat blood are suitable alternatives to sheep blood for use in bacteriological media in settings where sheep and horse blood are not readily available.

  14. An Agar-Based Method for Plating Marine Protozoan Parasites of the Genus Perkinsus.

    PubMed

    Cold, Emma R; Freyria, Nastasia J; Martínez Martínez, Joaquín; Fernández Robledo, José A

    2016-01-01

    The genus Perkinsus includes protozoan parasites of mollusks responsible for losses in the aquaculture industry and hampering the recovery of natural shellfish beds worldwide, and they are a key taxon for understanding intracellular parasitism adaptations. The ability to propagate the parasite in liquid media, in the absence of the host, has been crucial for improving understanding of its biology; however, alternative techniques to grow the parasite are needed to explore other basic aspects of the Perkinsus spp. biology. We optimized a DME: Ham's F12-5% FBS- containing solid agar medium for plating Perkinsus marinus. This solid medium supported trophozoite propagation both by binary fission and schizogony. Colonies were visible to the naked eye 17 days after plating. We tested the suitability of this method for several applications, including the following: 1) Subcloning P. marinus isolates: single discrete P. marinus colonies were obtained from DME: Ham's F12-5% FBS- 0.75% agar plates, which could be further propagated in liquid medium; 2) Subcloning engineered Perkinsus mediterraneus MOE[MOE]: GFP by streaking cultures on plates; 3) Chemical susceptibility: Infusing the DME: Ham's F12-5% FBS- 0.75% agar plates with triclosan resulted in inhibition of the parasite propagation in a dose-dependent manner. Altogether, our plating method has the potential for becoming a key tool for investigating diverse aspects of Perkinsus spp. biology, developing new molecular tools, and for biotechnological applications.

  15. Isolation and characterization of agar-degrading endophytic bacteria from plants.

    PubMed

    Song, Tao; Zhang, Weijia; Wei, Congchong; Jiang, Tengfei; Xu, Hui; Cao, Yi; Cao, Yu; Qiao, Dairong

    2015-02-01

    Agar is a polysaccharide extracted from the cell walls of some macro-algaes. Among the reported agarases, most of them come from marine environment. In order to better understand different sources of agarases, it is important to search new non-marine native ones. In this study, seven agar-degrading bacteria were first isolated from the tissues of plants, belonging to three genera, i.e., Paenibacillus sp., Pseudomonas sp., and Klebsiella sp. Among them, the genus Klebsiella was first reported to have agarolytic ability and the genus Pseudomonas was first isolated from non-marine environment with agarase activity. Besides, seven strains were characterized by investigating the growth and agarase production in the presence of various polysaccharides. The results showed that they could grow on several polysaccharides such as araban, carrageenan, chitin, starch, and xylan. Besides, they could also produce agarase in the presence of different polysaccharides other than agar. Extracellular agarases from seven strains were further analyzed by SDS-PAGE combined with activity staining and estimated to be 75 kDa which has great difference from most reported agarases.

  16. Simulation of Bacillus subtilis biofilm growth on agar plate by diffusion-reaction based continuum model

    NASA Astrophysics Data System (ADS)

    Zhang, Xianlong; Wang, Xiaoling; Nie, Kai; Li, Mingpeng; Sun, Qingping

    2016-08-01

    Various species of bacteria form highly organized spatially-structured aggregates known as biofilms. To understand how microenvironments impact biofilm growth dynamics, we propose a diffusion-reaction continuum model to simulate the formation of Bacillus subtilis biofilm on an agar plate. The extended finite element method combined with level set method are employed to perform the simulation, numerical results show the quantitative relationship between colony morphologies and nutrient depletion over time. Considering that the production of polysaccharide in wild-type cells may enhance biofilm spreading on the agar plate, we inoculate mutant colony incapable of producing polysaccharide to verify our results. Predictions of the glutamate source biofilm’s shape parameters agree with the experimental mutant colony better than that of glycerol source biofilm, suggesting that glutamate is rate limiting nutrient for Bacillus subtilis biofilm growth on agar plate, and the diffusion-limited is a better description to the experiment. In addition, we find that the diffusion time scale is of the same magnitude as growth process, and the common-employed quasi-steady approximation is not applicable here.

  17. Predicting the growth situation of Pseudomonas aeruginosa on agar plates and meat stuffs using gas sensors

    PubMed Central

    Gu, Xinzhe; Sun, Ye; Tu, Kang; Dong, Qingli; Pan, Leiqing

    2016-01-01

    A rapid method of predicting the growing situation of Pseudomonas aeruginosa is presented. Gas sensors were used to acquire volatile compounds generated by P. aeruginosa on agar plates and meat stuffs. Then, optimal sensors were selected to simulate P. aeruginosa growth using modified Logistic and Gompertz equations by odor changes. The results showed that the responses of S8 or S10 yielded high coefficients of determination (R2) of 0.89–0.99 and low root mean square errors (RMSE) of 0.06–0.17 for P. aeruginosa growth, fitting the models on the agar plate. The responses of S9, S4 and the first principal component of 10 sensors fit well with the growth of P. aeruginosa inoculated in meat stored at 4 °C and 20 °C, with R2 of 0.73–0.96 and RMSE of 0.25–1.38. The correlation coefficients between the fitting models, as measured by electronic nose responses, and the colony counts of P. aeruginosa were high, ranging from 0.882 to 0.996 for both plate and meat samples. Also, gas chromatography–mass spectrometry results indicated the presence of specific volatiles of P. aeruginosa on agar plates. This work demonstrated an acceptable feasibility of using gas sensors—a rapid, easy and nondestructive method for predicting P. aeruginosa growth. PMID:27941841

  18. Identification of bacteria causing acute otitis media using Raman microspectroscopy

    NASA Astrophysics Data System (ADS)

    Ayala, Oscar D.; Wakeman, Catherine A.; Skaar, Eric P.; Mahadevan-Jansen, Anita

    2016-03-01

    Otitis media (OM) is the leading cause of acute physician visits and prescription of antibiotics for children. Current standard techniques to diagnose acute otitis media (AOM) are limited by their ability to probe only changes in symptoms of the bacterial infection that cause AOM. Furthermore, they are not able to detect the presence of or identify bacteria causing AOM, which is important for diagnosis and proper antibiotic treatment. Our goal is to detect the presence of and identify the pathogens involved in causing AOM based on their biochemical profile using Raman spectroscopy (RS). An inVia confocal Raman microscope (Renishaw) at 785 nm was used to detect bacteria causing AOM in vitro. The three main bacteria that cause AOM, Haemophilus influenzae, Moraxella catarrhalis, and Streptococcus pneumoniae were cultured in chocolate agar and Mueller-Hinton agar to determine which agar type would minimize Raman signal from the growth agar. Preliminary results identified specific Raman spectral features characteristic of S. pneumoniae. RS has the potential to accurately diagnose AOM, which will help in identifying the antibiotic that will be most beneficial for the patient and ultimately decrease the course of infection.

  19. Comparative evaluation of chromogenic agar medium and conventional culture system for isolation and presumptive identification of uropathogens

    PubMed Central

    Akter, Laila; Haque, Rezwana; Salam, Md. Abdus

    2014-01-01

    Objective: Urine is the most frequent specimen received for culture/sensitivity by clinical laboratories. The microbiological performance of HiCrome UTI agar medium was compared with Blood agar and MacConkey agar for isolation and presumptive identification of bacteria from urine culture. Methods: A total of 443 consecutively collected midstream and/or catheter-catch urine samples from patients attending the Islami Bank Medical College Hospital, Rajshahi, Bangladesh during January to December, 2012 were cultured. Urine samples showing pus cells ≥ 5/HPF were inoculated on to Blood agar (BA), MacConkey agar (MAC) and HiCrome UTI agar (CA) media simultaneously and incubated overnight aerobically at 370C. Rate of isolation and presumptive identification of bacterial species were compared for different media. Results: Culture yielded a total of 199 bacterial isolates from 189 (42.67%) positive plates including 179 (40.40%) unimicrobial and 10 (2.26%) polymicrobial (mixed growth of pair of bacteria) growths. Both HiCrome UTI agar and Blood agar media supported 100% growths while 151 (75.88%) growths were observed on MacConkey agar. The rate of presumptive identification was found significantly higher on HiCrome UTI agar (97.49%) than MAC agar (67.34%) (P<0.001) as primary urine culture medium. Of 199 isolates, E. coli was found to be the leading uropathogen isolated from 118 (59.30%) samples with its presumptive identification rate of 95.76%, 93.22% and 5.93% on CA, MAC and BA respectively. All 10 (100%) polymicrobial growths were demonstrated distinctly on CA against only 01(10%) on each BA and MAC. Conclusion: HiCrome UTI agar was found to be more useful as primary urine culture medium in both higher rate of isolation and presumptive identification of uropathogens in comparison to conventional media. Its inherent characteristics in demonstrating polymicrobial growth and ease of rapid identification by distinct colony colour are unique. PMID:25225521

  20. Comparison of performance of the novel chromogenic spectra VRE agar to that of bile esculin azide and Campylobacter agars for detection of vancomycin-resistant enterococci in fecal samples.

    PubMed

    Jenkins, S G; Raskoshina, L; Schuetz, A N

    2011-11-01

    A total of 142 stool specimens were evaluated for vancomycin-resistant enterococcus (VRE). Twenty-four-hour sensitivities and specificities, respectively, were 98% and 95% for Spectra VRE chromogenic agar (Remel, Lenexa, KS), 86% and 92% for bile esculin azide with vancomycin (BEAV; Remel), and 96.5% and 92% for Campylobacter agar (CAMPY; Remel). Spectra VRE and CAMPY are significantly more sensitive at 24 h than BEAV.

  1. Virulence conversion of Legionella pneumophila: a one-way phenomenon.

    PubMed Central

    Catrenich, C E; Johnson, W

    1988-01-01

    Previous investigations have shown that Legionella pneumophila converts from virulence to avirulence after passage on supplemented Mueller-Hinton (SMH) agar and may convert back to virulence after passage in guinea pigs. However, there is no additional information concerning the apparent interconversion of virulent and avirulent derivatives of L. pneumophila cultures. We investigated the stability of a parental virulent culture and its avirulent derivatives and the growth and viability of these cultures on charcoal-yeast extract (CYE) and SMH agars. Avirulent derivatives of a highly virulent L. pneumophila culture were obtained by passage of the virulent parent culture on SMH agar. The only time a virulent L. pneumophila culture was recoverable from an avirulent culture was when the avirulent culture was derived from a saline suspension of a virulent culture which had been passaged only five times on SMH agar. When an avirulent culture was derived from a virulent culture passaged 25 times on SMH agar or from an isolated colony which grew on a SMH agar plate, we were unable to recover a virulent culture after successive passage through guinea pigs. These results suggest that the conversion process which occurs between virulent and avirulent forms of L. pneumophila is a one-way phenomenon from virulence to avirulence and that stable avirulent derivatives can be isolated. Furthermore, our findings suggest that SMH agar acts as a selective medium for the growth of avirulent L. pneumophila, and growth on SMH agar may be a phenotypic marker for avirulence. Virulent cells, although unable to grow on SMH agar, may remain viable for several passages on SMH agar and propagate when inoculated into guinea pigs. Images PMID:3182073

  2. Evaluation of a new agar in Uricult-Trio for rapid detection of Escherichia coli in urine.

    PubMed Central

    Dalet, F; Segovia, T

    1995-01-01

    A new commercial agar (Uricult-Trio) with 8-hydroxyquinoline-beta-glucuronide was used to assess 2,536 uropathogens for beta-glucuronidase activity typical of Escherichia coli. Included in the study were 1,807 strains of the family Enterobacteriaceae, 284 strains of nonfermentative bacilli, 345 strains of gram-positive cocci, and 100 yeast strains. In identifying E. coli, the test agar gave a sensitivity of 95.5% and a specificity of 97.2%. Fifty E. coli isolates gave negative reactions; 31 non-E. coli strains produced black colonies characteristic of E. coli. No growth of gram-positive cocci and no false-positive reactions from yeasts were observed. The recovery rate for E. coli on this agar was at least 10% higher than that on blood agar. PMID:7615766

  3. Antiserum-agar plate method for simultaneous detection and direct isolation of Legionella species in clinical and environmental specimens.

    PubMed Central

    Janssen, W A; Hedlund, K W

    1982-01-01

    Colonies of Legionella pneumophila serotypes 1 through 6, L. micdadei, L. bozemanii, L. dumoffii, and L. gormanii, which were developed on filtered yeast extract agar containing polyvalent antiserum, were surrounded by distinct, specific precipitin rings. Images PMID:7050153

  4. Prospective Two-Center Comparison of Three Chromogenic Agars for Methicillin-Resistant Staphylococcus aureus Screening in Hospitalized Patients

    PubMed Central

    Verhulst, Carlo; Nonhoff, Claire; Nagant, Carole; Denis, Olivier; Kluytmans, Jan

    2015-01-01

    Three chromogenic media, chromID MRSA SMART (SMART), chromID MRSA first generation (chromID), and Brilliance MRSA (OX2), were evaluated for methicillin-resistant Staphylococcus aureus (MRSA) screening using 1,220 samples. The sensitivity at 24 h was significantly better with the SMART agar (66.4%) than that with chromID agar (50.5%). Enrichment and incubation until 48 h are still needed for an optimal yield. PMID:26109446

  5. Trace Amounts of Furan-2-Carboxylic Acids Determine the Quality of Solid Agar Plates for Bacterial Culture

    PubMed Central

    Hara, Shintaro; Isoda, Reika; Tahvanainen, Teemu; Hashidoko, Yasuyuki

    2012-01-01

    Background Many investigators have recognised that a significant proportion of environmental bacteria exist in a viable but non-culturable state on agar plates, and some researchers have also noticed that some of such bacteria clearly recover their growth on matrices other than agar. However, the reason why agar is unsuitable for the growth of some bacteria has not been addressed. Methodology/Principal Findings According to the guide of a bioassay for swarming inhibition, we identified 5-hydroxymethylfuran-2-carboxylic acid (5-HMFA) and furan-2-carboxylic acid (FA) as factors that inhibit bacterial swarming and likely inhibit extracellular polysaccharide production on agar. The furan-2-carboxylic acids 5-HMFA and FA effectively inhibited the swarming and swimming of several environmental bacteria at concentrations of 1.8 and 2.3 µg L−1 (13 and 21 nmol L−1), respectively, which are equivalent to the concentrations of these compounds in 0.3% agar. On Luria-Bertani (LB) plates containing 1.0% agar that had been previously washed with MeOH, a mixture of 5-HMFA and FA in amounts equivalent to their original concentrations in the unwashed agar repressed the swarming of Escherichia coli K12 strain W3110, a representative swarming bacterium. Conclusions/Significance Agar that contains trace amounts of 5-HMFA and FA inhibits the proliferation of some slow-growing or difficult-to-culture bacteria on the plates, but it is useful for single colony isolation due to the ease of identification of swarmable bacteria as the non-swarmed colonies. PMID:22848437

  6. Cavitation-enhanced delivery of insulin in agar and porcine models of human skin

    NASA Astrophysics Data System (ADS)

    Feiszthuber, Helga; Bhatnagar, Sunali; Gyöngy, Miklós; Coussios, Constantin-C.

    2015-03-01

    Ultrasound-assisted transdermal insulin delivery offers a less painful and less invasive alternative to subcutaneous insulin injections. However, ultrasound-based drug delivery, otherwise known as sonophoresis, is a highly variable phenomenon, in part dependent on cavitation. The aim of the current work is to investigate the role of cavitation in transdermal insulin delivery. Fluorescently stained, soluble Actrapid insulin was placed on the surface of human skin-mimicking materials subjected to 265 kHz, 10% duty cycle focused ultrasound. A confocally and coaxially aligned 5 MHz broadband ultrasound transducer was used to detect cavitation. Two different skin models were used. The first model, 3% agar hydrogel, was insonated with a range of pressures (0.25-1.40 MPa peak rarefactional focal pressure—PRFP), with and without cavitation nuclei embedded within the agar at a concentration of 0.05% w/v. The second, porcine skin was insonated at 1.00 and 1.40 MPa PRFP. In both models, fluorescence measurements were used to determine penetration depth and concentration of delivered insulin. Results show that in agar gel, both insulin penetration depth and concentration only increased significantly in the presence of inertial cavitation, with up to a 40% enhancement. In porcine skin the amount of fluorescent insulin was higher in the epidermis of those samples that were exposed to ultrasound compared to the control samples, but there was no significant increase in penetration distance. The results underline the importance of instigating and monitoring inertial cavitation during transdermal insulin delivery.

  7. Cavitation-enhanced delivery of insulin in agar and porcine models of human skin.

    PubMed

    Feiszthuber, Helga; Bhatnagar, Sunali; Gyöngy, Miklós; Coussios, Constantin-C

    2015-03-21

    Ultrasound-assisted transdermal insulin delivery offers a less painful and less invasive alternative to subcutaneous insulin injections. However, ultrasound-based drug delivery, otherwise known as sonophoresis, is a highly variable phenomenon, in part dependent on cavitation. The aim of the current work is to investigate the role of cavitation in transdermal insulin delivery. Fluorescently stained, soluble Actrapid insulin was placed on the surface of human skin-mimicking materials subjected to 265 kHz, 10% duty cycle focused ultrasound. A confocally and coaxially aligned 5 MHz broadband ultrasound transducer was used to detect cavitation. Two different skin models were used. The first model, 3% agar hydrogel, was insonated with a range of pressures (0.25-1.40 MPa peak rarefactional focal pressure-PRFP), with and without cavitation nuclei embedded within the agar at a concentration of 0.05% w/v. The second, porcine skin was insonated at 1.00 and 1.40 MPa PRFP. In both models, fluorescence measurements were used to determine penetration depth and concentration of delivered insulin. Results show that in agar gel, both insulin penetration depth and concentration only increased significantly in the presence of inertial cavitation, with up to a 40% enhancement. In porcine skin the amount of fluorescent insulin was higher in the epidermis of those samples that were exposed to ultrasound compared to the control samples, but there was no significant increase in penetration distance. The results underline the importance of instigating and monitoring inertial cavitation during transdermal insulin delivery.

  8. Methicillin-Resistant Staphylococcus aureus Grown on Vancomycin-Supplemented Screening Agar Displays Enhanced Biofilm Formation

    PubMed Central

    Chang, Wenjiao; Ding, Ding; Zhang, Shanshan; Dai, Yuanyuan; Pan, Qing; Lu, Huaiwei; Luo, Qingli; Shen, Jilong

    2015-01-01

    Brain heart infusion agar containing 3 mg/liter vancomycin (BHI-V3) was used to screen for heterogeneous vancomycin-intermediate Staphylococcus aureus (hVISA). There was markedly greater biofilm formation by isolates that grew on BHI-V3 than by strains that did not grow on BHI-V3. Increased biofilm formation by hVISA may be mediated by FnbA- and polysaccharide intercellular adhesin-dependent pathways, and upregulation of atlA and sarA may also contribute to enhanced biofilm formation by hVISA upon prolonged exposure to vancomycin. PMID:26459889

  9. Coma in the course of severe poisoning after consumption of red fly agaric (Amanita muscaria).

    PubMed

    Mikaszewska-Sokolewicz, Małgorzata A; Pankowska, Sylwestra; Janiak, Marek; Pruszczyk, Piotr; Łazowski, Tomasz; Jankowski, Krzysztof

    2016-01-01

    Red fly agaric poisoning is rare. It can be consumed for suicidal purposes or its psychedelic effect. The paper describes the case of a young men, who fell into a coma after ingestion of the red toadstools. Quick identification of the poison, early use of gastric lavage and symptomatic treatment resulted in regression of symptoms and lead to the patient's discharge from the hospital on the third day after intoxication. Authors discussing the poisonous alkaloids contained in the red toadtools: ibotenic acid, muscimol, muscasone and muscarine and theirs properties, responsible for the symptoms of intoxication.

  10. CHROMagar Yersinia, a New Chromogenic Agar for Screening of Potentially Pathogenic Yersinia enterocolitica Isolates in Stools

    PubMed Central

    Renaud, Nicolas; Lecci, Laetitia; Courcol, René J.; Simonet, Michel

    2013-01-01

    CHROMagar Yersinia (CAY) is a new chromogenic medium for the presumptive detection of virulent Yersinia enterocolitica in stools. Based on a comparative analysis of 1,494 consecutive stools from hospitalized patients, CAY was found to be just as sensitive as the reference medium (cefsulodin-irgasan-novobiocin agar) but was significantly more specific and had a very low false-positive rate. CAY reduces the workload (and thus costs) for stool analysis and can therefore be recommended for routine laboratory use. PMID:23363840

  11. Comparative study of 6-APA production by free and agar immobilized bacteria in nutrient broth culture.

    PubMed

    Dolui, A K; Das, S

    2011-04-01

    In the present study different bacterial samples were isolated from soil of different places of Dibrugarh and screened for biotransformation ability to produce 6-Aminopenicillanic acid. Among ten isolated bacterial samples, three gram positive bacterial samples designated as AKDD-2, AKDD-4 and AKDD-6 showed the production of 6-APA from penicillin G. Assessment of production of 6-APA after incubation in penicillin G (2 mg/ml) by three different samples separately in free and agar immobilization state was done by HPLC analysis. Reusability of immobilized cells was found successful up to 14 days.

  12. Rapid identification of Candida albicans by using Albicans ID and fluoroplate agar plates.

    PubMed Central

    Rousselle, P; Freydiere, A M; Couillerot, P J; de Montclos, H; Gille, Y

    1994-01-01

    Two commercially available agar media, Albicans ID and Fluoroplate, that use a chromogenic or a fluorogenic substrate for the detection and identification of Candida albicans were evaluated. From 1,006 clinical samples containing 723 yeast strains, 352 C. albicans strains were detected with either of the two media. The sensitivity of each of the two media was 93.8% and the specificity was 98.6%, with five false-positive reactions for Candida tropicalis and no false-negative reactions. PMID:7883894

  13. The Efficiency of UVC Radiation in the Inactivation of
Listeria monocytogenes on Beef-Agar Food Models

    PubMed Central

    James, Christian; James, Stephen

    2015-01-01

    Summary The aim of this study is to evaluate the effect of meat content and surface smoothness on the deactivation of Listeria monocytogenes in beef-agar food models achieved by shortwave ultraviolet (UVC) light. Food models with various meat contents were made using chopped beef slices and agar solution. Prepared models together with a Listeria selective agar (LSA) plate and a slice of cooked beef were inoculated with L. monocytogenes and then exposed to UVC light. Population of Listeria reduced to below the level of detection on the LSA plates. As the content of beef in the beef-agar models increased, more L. monocytogenes cells survived. Survival was greatest on the treated cooked slice of beef. To better understand the effect of surface irregularities, a white light interferometer was used to analyse the surface smoothness of beef-agar media and LSA plates. No correlation was observed between the surface roughness of seven out of nine types of produced beef-agar media and the degree of inactivation resulting from UVC radiation at the given dose, whereas, less bacterial cells were killed as beef content of the food models increased. The findings of the current study show that the chemical composition of the treated sample also plays an important role in pathogen resistance and survival, meaning that two samples with similar surface irregularities but different chemical composition might produce very different inactivation results when exposed to UVC light. PMID:27904353

  14. Antibiotic susceptibility of Stenotrophomonas (Xanthomonas) maltophilia: comparative (NCCLS criteria) evaluation of antimicrobial drugs with the agar dilution and the agar disk diffusion (Bauer-Kirby) tests.

    PubMed

    Traub, W H; Leonhard, B; Bauer, D

    1998-01-01

    Ninety-six clinical isolates of Stenotrophomonas maltophilia were examined with the agar dilution method for susceptibility to 19 antimicrobial drugs. Doxycycline, cotrimoxazole, timentin, ofloxacin, fosfomycin, and piperacillin + tazobactam, in that order, inhibited the majority of strains. All isolates were resistant to nitrofurantoin. Concurrent disk susceptibility (Bauer-Kirby method) testing, using currently valid NCCLS interpretative criteria for Pseudomonas aeruginosa, uncovered a significant incidence of very major (category I), major (category II), and minor (categories III and IV) discrepancies for aminoglycosides, cephalosporins, chloramphenicol, and piperacillin + tazobactam and ticarcillin + clavulanic acid. Therefore, new interpretative criteria indicative of intermediate (I) susceptibility of S. maltophilia to these various antibiotics were proposed. In addition, new intermediate susceptibility criteria were proposed for the two beta-lactam-beta-lactamase inhibitor combinations. It was recommended to exclude ciprofloxacin from test batteries against this microorganism due to the wide scatter of minimal inhibitory concentration values and diameters of inhibition zones; the same was true for polymyxin B. It is hoped that the proposed modified, species-specific criteria will improve the clinical utility of laboratory-generated disk antibiograms with respect to the inherently multiple antibiotic-resistant, opportunistic pathogen S. maltophilia.

  15. Antibacterial synergy of curcumin with antibiotics against biofilm producing clinical bacterial isolates

    PubMed Central

    Kali, Arunava; Bhuvaneshwar, Devaraj; Charles, Pravin M. V.; Seetha, Kunigal Srinivasaiah

    2016-01-01

    Introduction: The role of natural bioactive substances in treating infections has been rediscovered as bacterial resistance become common to most of the antibiotics. Curcumin is a bioactive substance from turmeric. Owing to antimicrobial properties, its prospect as an antibacterial agent is currently under focus. Materials and Methods: We have evaluated the in vitro synergy of curcumin with antibiotics against sixty biofilm producing bacterial isolates. Congo red agar method was used to identify the biofilm producing isolates. Curcumin minimum inhibitory concentration (MIC) was determined by agar dilution method. Its antibiotic synergy was identified by the increase in disc diffusion zone size on Mueller-Hinton agar with 32 mg/L curcumin. Results: The mean MICs of curcumin against Gram-positive and Gram-negative isolates were 126.9 mg/L and 117.4 mg/L, respectively. Maximum synergy was observed with ciprofloxacin among Gram-positive and amikacin, gentamicin, and cefepime among Gram-negative isolates. Conclusions: Curcumin per se as well as in combination with other antibiotics has a demonstrable antibacterial action against biofilm producing bacterial isolates. It may have a beneficial role in supplementing antibiotic therapy. PMID:27330262

  16. PubMed Central

    Nicolas, P.; Cavallo, J. D.; Fabre, R.; Martet, G.

    1998-01-01

    Studying the susceptibility of 189 Neisseria meningitidis strains to penicillin, amoxicillin, cefotaxime, ceftriaxone, chloramphenicol and rifampicin by determination of minimum inhibitory concentrations (MICs) by agar dilution (reference method), E-test and disc diffusion method on Mueller-Hinton agar at 37 degrees C with 5% CO2 enabled us to standardize the antibiograms. While MIC determination by agar dilution is still the reference method, it is possible to obtain exact or approximate MIC values using the E-test. For laboratories that cannot determine penicillin MICs, it is impossible to detect strains that are relatively resistant to penicillin (RRP strains: 0.1 < or = MIC < or = 1 mg/l) using a 10-U penicillin disc. A 1 microgram-oxacillin disc allows MIC to be determined in most cases when the oxacillin inhibition zone is < or = 10 mm. Such strains must be sent to a reference laboratory for exact MIC determination. Based on our results and literature data on pharmacokinetics, we propose critical concentrations for these various antibiotics as well as critical diameters for chloramphenicol and rifampicin discs. PMID:9803590

  17. [Standardization of the Neisseria meningitidis antibiogram. Detection of strains relatively resistant to penicillin].

    PubMed

    Nicolas, P; Cavallo, J D; Fabre, R; Martet, G

    1998-01-01

    Studying the susceptibility of 189 Neisseria meningitidis strains to penicillin, amoxicillin, cefotaxime, ceftriaxone, chloramphenicol and rifampicin by determination of minimum inhibitory concentrations (MICs) by agar dilution (reference method), E-test and disc diffusion method on Mueller-Hinton agar at 37 degrees C with 5% CO2 enabled us to standardize the antibiograms. While MIC determination by agar dilution is still the reference method, it is possible to obtain exact or approximate MIC values using the E-test. For laboratories that cannot determine penicillin MICs, it is impossible to detect strains that are relatively resistant to penicillin (RRP strains: 0.1 < or = MIC < or = 1 mg/l) using a 10-U penicillin disc. A 1 microgram-oxacillin disc allows MIC to be determined in most cases when the oxacillin inhibition zone is < or = 10 mm. Such strains must be sent to a reference laboratory for exact MIC determination. Based on our results and literature data on pharmacokinetics, we propose critical concentrations for these various antibiotics as well as critical diameters for chloramphenicol and rifampicin discs.

  18. Penetration barrier contributes to bacterial biofilm-associated resistance against only select antibiotics, and exhibits genus-, strain- and antibiotic-specific differences.

    PubMed

    Singh, Rachna; Sahore, Simmi; Kaur, Preetinder; Rani, Alka; Ray, Pallab

    2016-08-01

    Bacterial biofilms are implicated in a wide range of implant-based and chronic infections. These infections are often associated with adverse therapeutic outcomes, owing to the decreased antibiotic susceptibility of biofilms compared with their planktonic counterparts. This altered biofilm susceptibility has been attributed to multiple factors, including a reduced antibiotic penetration. Although several studies have addressed the role of penetration barrier in biofilm-associated drug resistance, it remains inconclusive. This study was done to elucidate antibiotic penetration through biofilms formed by Staphylococcus aureus, S. epidermidis, Escherichia coli and Klebsiella pneumoniae, using an agar disk diffusion assay. Penetration capacity of six antimicrobial drugs from different classes (β-lactams, aminoglycosides, tetracyclines, phenicols, fluoroquinolones and glycopeptides) through biofilms formed by standard strains and clinical isolates from catheter-related bloodstream infections (CRBSI) was elucidated by measuring their growth-inhibition zones in lawn cultures on Mueller-Hinton agar, following diffusion of an antibiotic from an overlying disk through their biofilm to the agar medium. Penetration of only select antimicrobials (vancomycin and chloramphenicol) was hindered through biofilms. There was considerable variation in biofilm-permeating capacity depending upon the genus, strain/CRBSI isolate and antibiotic tested. Furthermore, antibiotics failed to kill the biofilm cells independent of penetration, indicating that other factors contributed substantially to biofilm resistance.

  19. Does tea tree oil have a place in the topical treatment of burns?

    PubMed

    Faoagali, J; George, N; Leditschke, J F

    1997-06-01

    Burnaid is a sorbalene-based cream containing 40 mg/g of tea tree oil and 1 mg/g of triclosan. This investigation was carried out to determine the effect of Burnaid, a commercial tea tree oil preparation, against Enterococcus faecalis (ATCC29212), Staphylococcus aureus (ATCC29213), Escherichia coli (ATCC25922), and Pseudomonas aeruginosa (ATCC27853), with the activity of the base product in the commercial preparation. The organisms were suspended in sterile saline (0.5 McFarland Standard) and inoculated onto horse blood agar (E. faecalis and S. aureus) or Mueller-Hinton agar (E. coli and P. aeruginosa). One hundred microliters of Burnaid unsterilized, Burnaid sterilized and the base product (Tinasolve) were placed in duplicate in wells cut into the agar plates. Sterility and inactivation cultures were also performed on the samples. None of the samples were found to be contaminated with bacteria prior to testing. Only S. aureus and E. coli showed zones of growth inhibition around the Burnaid and Tinasolve. Zones of growth inhibition (22 mm) were similar for the active product (Burnaid) and the base (Tinasolve). There was no activity against E. faecalis or P. aeruginosa. In view of our findings and literature indicating the cytotoxicity of tea tree oil against human fibroblasts and epithelial cells, it is recommended that this product should not be used on burn wounds.

  20. Evaluation of commercial selective agars in screening for methicillin-resistant Staphylococcus aureus.

    PubMed

    Yang, Hee-Young; Suh, Jin-Tae; Lee, Hee-Joo

    2010-01-01

    To evaluate methicillin-resistant S. aureus (MRSA) detection methods, we compared (a) mannitol salt agar with cefoxitin (MSA-FX), (b) MRSASelect agar (Bio-Rad), (c) MRSA ID (bioMerieuex), and (d) CHROMagar MRSA (BD Diagnostics) as selective media for culturing nasal swab specimens collected from intensive care unit (ICU) patients and healthcare personnel. A total of 99 (17.1%) cases of MRSA were recovered from 578 specimens. Four (5.5%) cases were identified from healthcare personnel and 95 (18.8%) were from ICU patients. The sensitivity of MSA-FX, MRSASelect, MRSA ID, and CHROMagar MRSA was 83.8, 87.9, 80.8, and 84.8% after 18 hr; 92.9, 94.9, 90.9, and 91.9% after 24 hr; and 96.0, 100, 99.0, and 99.0% after 48 hr, respectively. The specificity of MSA-FX, MRSASelect, MRSA ID, and CHROMagar MRSA was 97.7, 99.0, 98.7. and 99.8% after 18 hr; 97.1, 98.5, 98.1, and 99.5% after 24 hr; and 95.2, 97.7, 97.9, and 99.0% after 48 hr, respectively. In conclusion, all four media showed good results after the 24 hr readings, but MRSA ID and CHROMagar MRSA media required readings at 48 hr due to increased sensitivity at this time point.

  1. Measuring Survival of Hematopoietic Cancer Cells with the Colony-Forming Assay in Soft Agar.

    PubMed

    Crowley, Lisa C; Waterhouse, Nigel J

    2016-08-01

    Colony-forming assays measure the ability of cells in culture to grow and divide into groups. Any cell that has the potential to form a colony may also have the potential to cause cancer or relapse in vivo. Colony-forming assays also provide an indirect measurement of cell death because any cell that is dead or dying will not continue to proliferate. The proliferative capacity of adherent cells such as fibroblasts can be determined by growing cells at low density on culture dishes and counting the number of distinct groups that form over time. Cells that grow in suspension, such as hematopoietic cells, cannot be assayed this way because the cells move freely in the media. Assays to determine the colony-forming ability of hematopoietic cells must therefore be performed in solid matrices that restrict large-scale movement of the cells. One such matrix is soft agar. This protocol describes the use of soft agar to compare the colony-forming ability of untreated hematopoietic cells to the colony-forming ability of hematopoietic cells that have been treated with a cytotoxic agent.

  2. Abolition of Swarming of Proteus by p-Nitrophenyl Glycerin: Application to Blood Agar Media

    PubMed Central

    Williams, Fred D.

    1973-01-01

    Comparative plate counts were made of Staphylococcus aureus and Streptococcus pyogenes growing on blood agar supplemented with individual chemicals to abolish the swarming of Proteus. B-phenylethanol, sodium azide, and p-nitrophenyl glycerin (PNPG) were used as anti-swarm agents. Each anti-swarm agent effectively abolished swarming for 24 h, but azide failed to control swarming for longer periods of incubation. In addition, azide displayed growth inhibition towards the staphylococci and streptococci resulting in no hemolysis and reduced viable cell numbers with the streptococci. Phenylethanol showed reduced viable cell numbers with the streptococci and unreliable hemolytic reactions. At 0.1 to 0.3 mM, PNPG proved to be a superior anti-swarm agent in that it showed no growth inhibition and allowed normal hemolysis, but abolished swarming for extended periods of time. When laboratory strains of Streptococcus pneumoniae, Klebsiella pneumoniae, Pseudomonas aeruginosa. Listeria monocytogenes, and Vibrio cholerae were screened on a blood agar medium containing 0.1 mm PNPG, they displayed similar growth and hemolytic characteristics to the identical medium without PNPG. PMID:4715553

  3. [Development of chromogenic agar medium for isolation of enterohaemorrhagic Escherichia coli O26].

    PubMed

    Ikedo, M; Komatsu, O; Hara-Kudo, Y; Yamamoto, S; Kumagai, S

    2001-04-01

    Agar media for isolation of enterohaemorrhagic Escherichia coli (EHEC) have been developed primarily for E. coli O157, because this bacterium has most frequently caused EHEC infection. However, there have been few studies for isolation of other serotypes of EHEC, and media appropriate for isolation of such organisms, especially from food samples, are not yet available. Among such serotypes, E. coli O26 has often been isolated from clinical specimens from patients and animals, but not from food samples in outbreaks, because of lack of an appropriate method for isolation. In this study, we tried to develop a new chromogenic agar medium for selective isolation of E. coli O26 using the characteristics of E. coli O26. Fifteen strains of E. coli O26, 11 strains of E. coli O157 and 36 strains of other sero-types E. coli were tested for fermentation of rhamnose, cellobiose, dulcitol, salicin, raffinose, sorbitol, sucrose, lactose, mannitol, arabinose, maltose, xylose and glucose. Rhamnose was fermented by all E. coli strains except for E. coli O26. The other substrates were not effective for differentiating E. coli O26 from the other strains of E. coli. Thus the medium containing rhamnose and 5-bromo-4-chloro-3-indolyl-beta-D-galactopyranoside, which is a substrate of beta-galactosidase specific to coliforms, produced a color of E. coli O26 colonies different from colors of the other bacteria. Furthermore, cefixime and sodium tellulite were added to the composition of the medium for gaining higher selectivity.

  4. Visualization of Biosurfactant Film Flow in a Bacillus subtilis Swarm Colony on an Agar Plate

    PubMed Central

    Kim, Kyunghoon; Kim, Jung Kyung

    2015-01-01

    Collective bacterial dynamics plays a crucial role in colony development. Although many research groups have studied the behavior of fluidic swarm colonies, the detailed mechanics of its motion remains elusive. Here, we developed a visualization method using submicron fluorescent beads for investigating the flow field in a thin layer of fluid that covers a Bacillus subtilis swarm colony growing on an agar plate. The beads were initially embedded in the agar plate and subsequently distributed spontaneously at the upper surface of the expanding colony. We conducted long-term live cell imaging of the B. subtilis colony using the fluorescent tracers, and obtained high-resolution velocity maps of microscale vortices in the swarm colony using particle image velocimetry. A distinct periodic fluctuation in the average speed and vorticity of flow in swarm colony was observed at the inner region of the colony, and correlated with the switch between bacterial swarming and growth phases. At the advancing edge of the colony, both the magnitudes of velocity and vorticity of flow in swarm colony were inversely correlated with the spreading speed of the swarm edge. The advanced imaging tool developed in this study would facilitate further understanding of the effect of micro vortices in swarm colony on the collective dynamics of bacteria. PMID:26343634

  5. An electrochemical approach to monitor pH change in agar media during plant tissue culture.

    PubMed

    Wang, Min; Ha, Yang

    2007-05-15

    In this work, metal oxide microelectrodes were developed to monitor pH change in agar media during plant tissue culture. An antimony wire was produced by a new approach "capillary melt method". The surface of the obtained antimony wire was oxidized in a potassium nitrate melt to fabricate an antimony oxide film for pH sensing. Characterization results show that the oxide layer grown on the wire surface consists of Sb(2)O(3) crystal phase. The sensing response, open-circuit potential, of the electrode has a good linear relationship (R(2)=1.00) with pH value of the test solution. Adding organic compounds into the test media would not affect the linear relationship, although the slope of the lines varied with different ingredients added. The antimony oxide electrodes were employed to continuously monitor pH change of agar culture media during a 2-week plant tissue culture of Dendrobium candidum. The antimony oxide electrode fabricated this way has the advantages of low cost, easy fabrication, fast response, and almost no contamination introduced into the system. It would be suitable for in situ and continuous pH measurement in many bio applications.

  6. Mechanical response of agar gel irradiated with Nd:YAG nanosecond laser pulses

    NASA Astrophysics Data System (ADS)

    Pérez-Gutiérrez, Francisco G.; Evans, Rodger; Camacho-López, Santiago; Aguilar, Guillermo

    2010-02-01

    Nanosecond long laser pulses are used in medical applications where precise tissue ablation with minimal thermal and mechanical collateral damage is required. When a laser pulse is incident on a material, optical energy will be absorbed by a combination of linear and nonlinear absorption according to both: laser light intensity and material properties. In the case of water or gels, the first results in heat generation and thermoelastic expansion; while the second results in an expanding plasma formation that launches a shock wave and a cavitation/boiling bubble. Plasma formation due to nonlinear absorption of nanosecond laser pulses is originated by a combination of multiphoton ionization and thermionic emission of free electrons, which is enhanced when the material has high linear absorption coefficient. In this work, we present measurements of pressure transients originated when 6 ns laser pulses are incident on agar gels with varying linear absorption coefficient, mechanical properties and irradiation geometry using laser radiant exposures above threshold for bubble formation. The underlying hypothesis is that pressure transients are composed of the superposition of both: shock wave originated by hot expanding plasma resulting from nonlinear absorption of optical energy and, thermoelastic expansion originated by heat generation due to linear absorption of optical energy. The objective of this work is to evaluate the relative contribution of each absorption mechanism to mechanical effects in agar gel. Real time pressure transients are recorded with PVDF piezoelectric sensors and time-resilved imaging from 50 μm to 10 mm away from focal point.

  7. Evaluation of brilliance CRE agar for the detection of carbapenem-resistant gram-negative bacteria.

    PubMed

    Bracco, Silvia; Migliavacca, Roberta; Pini, Beatrice; Corbo, Nicoletta; Nucleo, Elisabetta; Brigante, Gioconda; Piazza, Aurora; Micheletti, Piero; Luzzaro, Francesco

    2013-04-01

    The aim of this work was to evaluate the performance of the new chromogenic medium BrillianceTM CREAgar (Thermo Fisher Scientific) for determining the limit of detection of carbapenem-resistant enterobacteria (CRE). A total of 70 clinical isolates were studied. Of these, 30 were well-characterized CRE, including Klebsiella pneumoniae strains producing KPC-, VIM-, and OXA-type enzymes, VIM-positive Enterobacter cloacae and Escherichia coli, NDM-positive E. coli, and enterobacterial isolates characterized by porin loss associated with ESBL production or AmpC hyperproduction. Ten carbapenem-resistant non-fermentative isolates were also included as well as 30 carbapenem-susceptible isolates. Carbapenem-resistant strains were inoculated at three different concentrations onto Brilliance CRE Agar (from 1.5x101 CFU/ml up to 1.5x104 CFU/ml) whereas carbapenem-susceptible isolates were inoculated at a concentration of 1.5x102 CFU/ml. The medium sustained the growth of carbapenem-resistant isolates, showing detection limits from 1.5x101 CFU/ml (in 31/40 cases) to 1.5x104 CFU/ml. No growth was observed with carbapenem-sensitive control strains. Our results indicate that the Brilliance CRE Agar allows the growth of carbapenem-resistant isolates with low detection limits and could represent a useful screening medium for both enterobacteria and non-fermentative Gram-negative strains resistant to carbapenems.

  8. Stable isotope ratios as a tool in microbial forensics--part 3. Effect of culturing on agar-containing growth media.

    PubMed

    Kreuzer-Martin, Helen W; Chesson, Lesley A; Lott, Michael J; Ehleringer, James R

    2005-11-01

    Stable isotope ratios of hydrogen and oxygen in microbes have been shown to be functions of the corresponding isotope ratios of the water with which the culture medium was prepared, and thus to contain a potential geographic signal. Water can evaporate from agar (solid) media during culturing, changing its isotope ratios. Here we describe the effect of drying on the isotope ratios of water extracted from agar media and the H and O stable isotope ratios ratios of Bacillus subtilis spores cultured on agar. The delta2H vs delta18O relationship of water in Petri dish agar was surprisingly constant during evaporation regardless of the ambient relative humidity, making it possible to calculate the approximate isotope ratios of the original water, even in significantly evaporated agar. The H stable isotope ratios of spores cultured on agar remained relatively unchanged as the agar dried, but the O ratio became significantly enriched.

  9. Multilaboratory Comparison of Proficiencies in Susceptibility Testing of Helicobacter pylori and Correlation between Agar Dilution and E Test Methods

    PubMed Central

    Best, L. M.; Haldane, D. J. M.; Keelan, M.; Taylor, D. E.; Thomson, A. B. R.; Loo, V.; Fallone, C. A.; Lyn, P.; Smaill, F. M.; Hunt, R.; Gaudreau, C.; Kennedy, J.; Alfa, M.; Pelletier, R.; Veldhuyzen van Zanten, S. J. O.

    2003-01-01

    Susceptibility testing was performed at seven Canadian microbiology laboratories and the Helicobacter Reference Laboratory, Halifax, Nova Scotia, Canada, to assess susceptibility testing proficiency and the reproducibility of the results for clarithromycin and metronidazole and to compare the Epsilometer test (E test) method to the agar dilution reference method. Control strain Helicobacter pylori ATCC 43504 (American Type Culture Collection) and 13 clinical isolates (plus duplicates of four of these strains including ATCC 43504) were tested blindly. The National Committee for Clinical Laboratory Standards (NCCLS) guidelines for agar dilution testing were followed, and the same suspension of organisms was used for agar dilution and E test. Antimicrobials and E test strips were provided to the investigators. Methods were provided on a website (www.Helicobactercanada.org). Each center reported MICs within the stated range for strain ATCC 43504. Compared to the average MICs, interlaboratory agreements within 2 log2 dilutions were 90% (range, 69 to 100%) for clarithromycin by agar dilution, with seven very major errors [VMEs], and 85% (range, 65 to 100%) by E test, with three VMEs. Interlaboratory agreements within 2 log2 dilutions were 83% (range, 50 to 100%) for metronidazole by agar dilution, with six VMEs and eight major errors (MEs), and 75% (range, 50 to 94%) by E test, with four VMEs and four MEs. At lower and higher concentrations of antibiotic, E test MICs were slightly different from agar dilution MICs, but these differences did not result in errors. When a standardized protocol based on NCCLS guidelines was used, most participants in this study correctly identified clarithromycin- and metronidazole-susceptible and -resistant strains of H. pylori 93% of the time by either the agar dilution or E test method, and the numbers of errors were relatively equivalent by both methods. PMID:14506021

  10. Multilaboratory comparison of proficiencies in susceptibility testing of Helicobacter pylori and correlation between agar dilution and E test methods.

    PubMed

    Best, L M; Haldane, D J M; Keelan, M; Taylor, D E; Thomson, A B R; Loo, V; Fallone, C A; Lyn, P; Smaill, F M; Hunt, R; Gaudreau, C; Kennedy, J; Alfa, M; Pelletier, R; Veldhuyzen Van Zanten, S J O

    2003-10-01

    Susceptibility testing was performed at seven Canadian microbiology laboratories and the Helicobacter Reference Laboratory, Halifax, Nova Scotia, Canada, to assess susceptibility testing proficiency and the reproducibility of the results for clarithromycin and metronidazole and to compare the Epsilometer test (E test) method to the agar dilution reference method. Control strain Helicobacter pylori ATCC 43504 (American Type Culture Collection) and 13 clinical isolates (plus duplicates of four of these strains including ATCC 43504) were tested blindly. The National Committee for Clinical Laboratory Standards (NCCLS) guidelines for agar dilution testing were followed, and the same suspension of organisms was used for agar dilution and E test. Antimicrobials and E test strips were provided to the investigators. Methods were provided on a website (www.Helicobactercanada.org). Each center reported MICs within the stated range for strain ATCC 43504. Compared to the average MICs, interlaboratory agreements within 2 log(2) dilutions were 90% (range, 69 to 100%) for clarithromycin by agar dilution, with seven very major errors [VMEs], and 85% (range, 65 to 100%) by E test, with three VMEs. Interlaboratory agreements within 2 log(2) dilutions were 83% (range, 50 to 100%) for metronidazole by agar dilution, with six VMEs and eight major errors (MEs), and 75% (range, 50 to 94%) by E test, with four VMEs and four MEs. At lower and higher concentrations of antibiotic, E test MICs were slightly different from agar dilution MICs, but these differences did not result in errors. When a standardized protocol based on NCCLS guidelines was used, most participants in this study correctly identified clarithromycin- and metronidazole-susceptible and -resistant strains of H. pylori 93% of the time by either the agar dilution or E test method, and the numbers of errors were relatively equivalent by both methods.

  11. Evaluation of the Granada agar plate for detection of vaginal and rectal group B streptococci in pregnant women.

    PubMed

    Gil, E G; Rodríguez, M C; Bartolomé, R; Berjano, B; Cabero, L; Andreu, A

    1999-08-01

    Granada medium was evaluated for the detection of group B streptococci (GBS) in vaginal and rectal swabs compared with selective Columbia blood agar and selective Lim broth. From May 1996 to March 1998, 702 pregnant women (35 to 37 weeks of gestation) participated in this three-phase study; 103 (14.7%) of these women carried GBS. In the first phase of the experiment (n = 273 women), vaginorectal specimens were collected on the same swab; the sensitivities of Granada tube, selective Columbia blood agar, and Lim broth were 31.4, 94.3, and 74.3%, respectively. In the second and third phases (n = 429 women), vaginal and rectal specimens were collected separately; the sensitivities of Granada plate, selective Columbia blood agar, and Lim broth (subcultured at 4 h on selective Columbia agar in the second phase and at 18 to 24 h in Granada plate in the third phase) were 91.1, 83.9, and 75%, respectively, in the second phase and 88.5, 90.4, and 63.5%, respectively, in the third phase. There were no statistically significant differences in GBS recovery between the Granada agar plate and selective Columbia blood agar, but the Granada plate provided a clear advantage; the characteristic red-orange colonies produced overnight by GBS can be identified by the naked eye and is so specific that further identification is unnecessary. The use of the Granada tube and Lim broth did not result in increased isolation of GBS. In conclusion, the Granada agar plate is highly sensitive for detecting GBS in vaginal and rectal swabs from pregnant women and can provide results in 18 to 24 h.

  12. Evaluation of the Granada Agar Plate for Detection of Vaginal and Rectal Group B Streptococci in Pregnant Women

    PubMed Central

    Gil, E. García; Rodríguez, M. C.; Bartolomé, R.; Berjano, B.; Cabero, L.; Andreu, A.

    1999-01-01

    Granada medium was evaluated for the detection of group B streptococci (GBS) in vaginal and rectal swabs compared with selective Columbia blood agar and selective Lim broth. From May 1996 to March 1998, 702 pregnant women (35 to 37 weeks of gestation) participated in this three-phase study; 103 (14.7%) of these women carried GBS. In the first phase of the experiment (n = 273 women), vaginorectal specimens were collected on the same swab; the sensitivities of Granada tube, selective Columbia blood agar, and Lim broth were 31.4, 94.3, and 74.3%, respectively. In the second and third phases (n = 429 women), vaginal and rectal specimens were collected separately; the sensitivities of Granada plate, selective Columbia blood agar, and Lim broth (subcultured at 4 h on selective Columbia agar in the second phase and at 18 to 24 h in Granada plate in the third phase) were 91.1, 83.9, and 75%, respectively, in the second phase and 88.5, 90.4, and 63.5%, respectively, in the third phase. There were no statistically significant differences in GBS recovery between the Granada agar plate and selective Columbia blood agar, but the Granada plate provided a clear advantage; the characteristic red-orange colonies produced overnight by GBS can be identified by the naked eye and is so specific that further identification is unnecessary. The use of the Granada tube and Lim broth did not result in increased isolation of GBS. In conclusion, the Granada agar plate is highly sensitive for detecting GBS in vaginal and rectal swabs from pregnant women and can provide results in 18 to 24 h. PMID:10405415

  13. Preparation and characterization of agar-based nanocomposite films reinforced with bimetallic (Ag-Cu) alloy nanoparticles.

    PubMed

    Arfat, Yasir Ali; Ahmed, Jasim; Jacob, Harsha

    2017-01-02

    Agar-based active nanocomposite films were prepared by incorporating silver-copper (Ag-Cu) alloy nanoparticles (NPs) (0.5-4wt%) into glycerol plasticized agar solution. Thermo-mechanical, morphological, structural, and optical properties of the nanocomposite films were characterized by texture analyzer, differential scanning calorimetry (DSC), scanning electron microscope (SEM), X-ray diffraction (XRD), Fourier transforms infrared (FTIR) spectroscopy, and surface color measurement. Tensile strength and the melting temperature of the film increased linearly with NPs loading concentration. Color, transparency and UV barrier properties of agar films were influenced by the reinforcement of Ag-Cu NPs. XRD analysis confirmed the crystalline structure of the Agar/Ag-Cu nanocomposite films, whereas the smoothness and the homogeneity of film surface strongly reduced as observed through the SEM. The nanocomposite films exhibited a profound antibacterial activity against both Gram-positive (Listeria monocytogenes) and Gram-negative (Salmonella enterica sv typhimurium) bacteria. Overall, the agar nanocomposite films could be used as packaging material for food preservation by controlling foodborne pathogens and spoilage bacteria.

  14. Infrared thermography analysis of thermal diffusion induced by RF magnetic field on agar phantoms loaded with magnetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Bante-Guerra, Jose; Macías, J. D.; Caballero-Aguilar, L.; Vales-Pinzón, C.; Alvarado-Gil, J. J.

    2013-02-01

    Recently, several treatments for fighting malignant tumors have been designed. However these procedures have well known inconveniences, depending on their applicability, tumor size and side effects, among others. Magnetic hyperthermia is a safe, non-invasive method for cancer therapy. This treatment is applied via elevation of target tissue temperature by dissipation of heat from Magnetic Nanoparticles (MNPs), previously located within the tumor. The induction of heat causes cell death and therefore the removal of the tumor. In this work the thermal diffusion in phantoms of agar loaded with magnetic nanoparticles (MNPs) is studied using the infrared thermography technique, which is widely used in biology/medicine (e.g. skin temperature mapping). Agar is one of the materials used to simulate different types of body tissues, these samples are known as "phantoms". Agar is of natural origin, low cost and high degree of biocompatibility. In this work the agar gel was embedded with MNPs by coprecipitation and placed in an alternating magnetic field radiation. As a consequence, the energy from the radiation source is dissipated as heat and then transferred from the MNP to the gel, increasing its temperature. For the temperature analysis, the samples of agar gel were stimulated by RF magnetic field generated by coils. Heating was measured with infrared thermography using a Thermovision A20M infrared camera. Thermographic images allowed obtaining the dependence of thermal diffusion in the phantom as a function of the magnitude of the applied RF magnetic field and the load of magnetic particles.

  15. Agar extraction from integrated multitrophic aquacultured Gracilaria vermiculophylla: evaluation of a microwave-assisted process using response surface methodology.

    PubMed

    Sousa, A M M; Alves, V D; Morais, S; Delerue-Matos, C; Gonçalves, M P

    2010-05-01

    Microwave-assisted extraction (MAE) of agar from Gracilaria vermiculophylla, produced in an integrated multitrophic aquaculture (IMTA) system, from Ria de Aveiro (northwestern Portugal), was tested and optimized using response surface methodology. The influence of the MAE operational parameters (extraction time, temperature, solvent volume and stirring speed) on the physical and chemical properties of agar (yield, gel strength, gelling and melting temperatures, as well as, sulphate and 3,6-anhydro-L-galactose contents) was evaluated in a 2(4) orthogonal composite design. The quality of the extracted agar compared favorably with the attained using traditional extraction (2 h at 85 degrees Celsius) while reducing drastically extraction time, solvent consumption and waste disposal requirements. Agar MAE optimum results were: an yield of 14.4 + or - 0.4%, a gel strength of 1331 + or - 51 g/cm(2), 40.7 + or - 0.2 degrees Celsius gelling temperature, 93.1 + or - 0.5 degrees Celsius melting temperature, 1.73 + or - 0.13% sulfate content and 39.4 + or - 0.3% 3,6-anhydro-L-galactose content. Furthermore, this study suggests the feasibility of the exploitation of G. vermiculophylla grew in IMTA systems for agar production.

  16. Evaluation of Albicans ID2 and Biggy agar for the isolation and direct identification of vaginal yeast isolates.

    PubMed

    Ilkit, Macit; Hilmioglu, Suleyha; Tasbakan, Meltem; Aydemir, Sohret

    2007-06-01

    In this study, 250 vaginal samples from patients with vulvovaginal candidosis were inoculated onto two chromogenic media, Albicans ID(2) and Biggy agar, as well as onto Sabouraud chloramphenicol agar, yielding a total of 63 yeast (25.2 %) on all three media. These strains were identified as Candida glabrata in 20 (31.8 %) samples, Candida albicans in 15 samples (23.8 %), Candida tropicalis in 10 samples (15.9 %), Candida krusei in five samples (7.9 %), Candida kefyr in five samples (7.9 %), Candida dubliniensis in four samples (6.3 %), Candida parapsilosis in two samples (3.2 %) and Candida guilliermondii in two samples (3.2 %). Mixed fungal cultures and bacterial growth or filamentous fungi were not detected on any of the selected media. The sensitivity and specificity of the Albicans ID(2) and Biggy agar with regard to the identification of C. albicans were 80.0 and 64.6 %, and 86.7 and 56.3 %, respectively. This study showed these two chromogenic media to be as effective as Sabouraud chloramphenicol agar with respect to fungal detection. However, neither Albicans ID(2) nor Biggy agar was sufficient for reliable differentiation of yeasts to the species level.

  17. Comparison of Mast Burkholderia Cepacia, Ashdown + Gentamicin, and Burkholderia Pseudomallei Selective Agar for the Selective Growth of Burkholderia Spp.

    PubMed

    Edler, Carola; Derschum, Henri; Köhler, Mirko; Neubauer, Heinrich; Frickmann, Hagen; Hagen, Ralf Matthias

    2017-03-01

    Reliable identification of pathogenic Burkholderia spp. like Burkholderia mallei and Burkholderia pseudomallei in clinical samples is desirable. Three different selective media were assessed for reliability and selectivity with various Burkholderia spp. and nontarget organisms. Mast Burkholderia cepacia agar, Ashdown + gentamicin agar, and B. pseudomallei selective agar were compared. A panel of 116 reference strains and well-characterized clinical isolates, comprising 30 B. pseudomallei, 20 B. mallei, 18 other Burkholderia spp., and 48 nontarget organisms, was used for this assessment. While all B. pseudomallei strains grew on all three tested selective agars, the other Burkholderia spp. showed a diverse growth pattern. Nontarget organisms, i.e., nonfermentative rod-shaped bacteria, other species, and yeasts, grew on all selective agars. Colony morphology did not allow unambiguous discrimination. While the assessed selective media reliably allowed the growth of a wide range of B. pseudomallei strains, growth of other Burkholderia spp. is only partially ensured. Growth of various nontarget organisms has to be considered. Therefore, the assessed media can only be used in combination with other confirmative tests in the diagnostic procedure for the screening for melioidosis or glanders.

  18. Isolation and characterization of agar-digesting Vibrio species from the rotten thallus of Gracilariopsis heteroclada Zhang et Xia.

    PubMed

    Martinez, Joval N; Padilla, Philip Ian P

    2016-08-01

    Gracilariopsis heteroclada Zhang et Xia (Gracilariaceae, Rhodophyta) is one of the most studied marine seaweeds due to its economic importance. This has been cultivated extensively on commercial scale in the Philippines and other Asian countries. However, sustainable production of G. heteroclada in the Philippines could not be maximized due to the occurrence of rotten thallus disease. Thus, isolation and characterization of agar-digesting bacteria from the rotten thalli of G. heteroclada was conducted. A total of seven representative bacterial isolates were randomly selected based on their ability to digest agar as evidenced by the formation of depressions around the bacterial colonies on nutrient agar plates supplemented with 1.5% NaCl and liquefaction of agar. Gram-staining and biochemical characterization revealed that isolates tested were gram-negative rods and taxonomically identified as Vibrio parahaemolyticus (86-99.5%) and Vibrio alginolyticus (94.2-97.7%), respectively. It is yet to be confirmed whether these agar-digesting vibrios are involved in the induction and development of rotten thallus disease in G. heteroclada in concomitance with other opportunistic bacterial pathogens coupled with adverse environmental conditions.

  19. Comparison of Mast Burkholderia Cepacia, Ashdown + Gentamicin, and Burkholderia Pseudomallei Selective Agar for the Selective Growth of Burkholderia Spp.

    PubMed Central

    Edler, Carola; Derschum, Henri; Köhler, Mirko; Neubauer, Heinrich; Frickmann, Hagen; Hagen, Ralf Matthias

    2017-01-01

    Reliable identification of pathogenic Burkholderia spp. like Burkholderia mallei and Burkholderia pseudomallei in clinical samples is desirable. Three different selective media were assessed for reliability and selectivity with various Burkholderia spp. and nontarget organisms. Mast Burkholderia cepacia agar, Ashdown + gentamicin agar, and B. pseudomallei selective agar were compared. A panel of 116 reference strains and well-characterized clinical isolates, comprising 30 B. pseudomallei, 20 B. mallei, 18 other Burkholderia spp., and 48 nontarget organisms, was used for this assessment. While all B. pseudomallei strains grew on all three tested selective agars, the other Burkholderia spp. showed a diverse growth pattern. Nontarget organisms, i.e., nonfermentative rod-shaped bacteria, other species, and yeasts, grew on all selective agars. Colony morphology did not allow unambiguous discrimination. While the assessed selective media reliably allowed the growth of a wide range of B. pseudomallei strains, growth of other Burkholderia spp. is only partially ensured. Growth of various nontarget organisms has to be considered. Therefore, the assessed media can only be used in combination with other confirmative tests in the diagnostic procedure for the screening for melioidosis or glanders. PMID:28386468

  20. Visualization of Thermal Distribution Caused by Focused Ultrasound Field in an Agar Phantom

    NASA Astrophysics Data System (ADS)

    Kim, Jungsoon; Kim, Moojoon; Ha, Kanglyeol

    2011-07-01

    Ultrasound waves have been widely used not only in medical diagnostic systems but also in medical treatment. There has been increasing interest in the thermal distribution caused by ultrasound waves. In this study, using thermochromic particles, a visualization method was suggested in a mimic phantom for organic materials. By blending various thermochromic particles with different critical temperatures, the thermal field distribution in the phantom could be observed. The effect of a concave-type ultrasound transducer on the temperature distribution in an agar phantom mixed with thermochromic particles was observed. The temperature distribution corresponded to changes in the brightness distribution of gray. It was confirmed that the thermal distribution pattern in the vicinity of the focal area varies with the time exposure to ultrasound waves.

  1. [Methicillin resistance and vancomycin susceptibility pattern among blood isolates of Staphylococcus aureus].

    PubMed

    Rodríguez-Pineda, Jonathan; Terrazas-Estrada, José Juan; Urdez-Hernández, Elena; Hernández-Sánchez, Eva Aurora; Sánchez-Tejeda, Sandra Leticia

    2016-01-01

    Introducción: el Staphylococcus aureus es capaz de desarrollar resistencia a todos los antimicrobianos. La vancomicina es clave para tratar infecciones graves causadas por S. aureus meticilino-resistente. Sin embargo, últimamente se reportan fallas terapéuticas. El objetivo fue establecer la resistencia a la meticilina y el perfil de susceptibilidad a la vancomicina del S. aureus. Métodos: de marzo a agosto del 2010, se determinó la meticilino-resistencia y la susceptibilidad a vancomicina de S. aureus aislados de hemocultivos, mediante el método estándar de microdilución. Para la meticilino-resistencia se utilizó una placa de agar Mueller-Hinton con 4 µg/mL de oxacilina, más NaCl al 2 % y una prueba de aglutinación. El desarrollo bacteriano o la aglutinación positiva identificaron al microorganismo meticilino-resistente. Para la susceptibilidad a vancomicina se determinó la concentración mínima inhibitoria (CMI) en placas de agar Mueller-Hinton con dilución de 16 a 0.5 µg/mL. Resultados: en total se incluyeron 25 S. aureus. El 60 % fue meticilino-resistente; el 100 % sensible a vancomicina (CMI ≤ 2 µg/mL), con las siguientes CMI: el 48 %, ≤ 0.5 µg/mL; 44 %, 1 µg/mL; y el 8 %, 2 µg/mL. Conclusión: la proporción alta de meticilino-resistencia y la evidencia de fenotipos sensibles a la vancomicina, pero asociados a falla terapéutica (CMI 2 µg/mL), demandan no solo el reforzamiento continuo de las precauciones estándar y el control de antimicrobianos sino también la vigilancia sistemática del patrón de susceptibilidad a la vancomicina con un método de referencia.

  2. Copper removal by algae Gelidium, agar extraction algal waste and granulated algal waste: kinetics and equilibrium.

    PubMed

    Vilar, Vítor J P; Botelho, Cidália M S; Boaventura, Rui A R

    2008-03-01

    Biosorption of copper ions by an industrial algal waste, from agar extraction industry has been studied in a batch system. This biosorbent was compared with the algae Gelidium itself, which is the raw material for agar extraction, and the industrial waste immobilized with polyacrylonitrile (composite material). The effects of contact time, pH, ionic strength (IS) and temperature on the biosorption process have been studied. Equilibrium data follow both Langmuir and Langmuir-Freundlich models. The parameters of Langmuir equilibrium model were: q(max)=33.0mgg(-1), K(L)=0.015mgl(-1); q(max)=16.7mgg(-1), K(L)=0.028mgl(-1) and q(max)=10.3mgg(-1), K(L)=0.160mgl(-1) respectively for Gelidium, algal waste and composite material at pH=5.3, T=20 degrees C and IS=0.001M. Increasing the pH, the number of deprotonated active sites increases and so the uptake capacity of copper ions. In the case of high ionic strengths, the contribution of the electrostatic component to the overall binding decreases, and so the uptake capacity. The temperature has little influence on the uptake capacity principally for low equilibrium copper concentrations. Changes in standard enthalpy, Gibbs energy and entropy during biosorption were determined. Kinetic data at different solution pH (3, 4 and 5.3) were fitted to pseudo-first-order and pseudo-second-order models. The adsorptive behaviour of biosorbent particles was modelled using a batch reactor mass transfer kinetic model, which successfully predicts Cu(II) concentration profiles.

  3. Evaluation of agar dilution and broth microdilution methods to determine the disinfectant susceptibility.

    PubMed

    Wu, Guoyan; Yang, Qianru; Long, Mei; Guo, Lijuan; Li, Bei; Meng, Yue; Zhang, Anyun; Wang, Hongning; Liu, Shuliang; Zou, Likou

    2015-11-01

    A variety of disinfectants have been widely used in veterinary hygiene, food industries and environments, which could induce the development of bacterial resistance to disinfectants. The methods used to investigate antimicrobial effects of disinfectant vary considerably among studies, making comparisons difficult. In this study, agar dilution and broth microdilution methods were used to compare the antimicrobial activities of four quaternary ammonium compounds (QACs) against foodborne and zoonotic pathogens. The potential relationship between the presence of QACs resistance genes and phenotypic resistance to QACs was also investigated. Our results indicated that the minimum inhibitory concentrations (MICs) determined by two methods might be different depended upon different QACs and bacteria applied. Regardless of the testing methods, Klebsiella pneumoniae was more tolerant among Gram-negative strains to four QACs, followed by Salmonella and Escherichia coli. The agreement between MICs obtained by the two methods was good, for benzalkonium chloride (78.15%), didecyldimethylammonium chloride (DDAC) (82.35%), cetylpyridinium chloride (CTPC) (97.48%) and cetyltrimethylammonium bromide (CTAB) (99.16%), respectively. Among all Gram-negative bacteria, 94.55% (n=52) of qacEΔ1-positive strains showed higher MICs (512 mg l(-1)) to CTAB. The qacEΔ1 gene was highly associated (P<0.05) with the high MICs of QACs (⩾512 mg l(-1)). In addition, DDAC remained as the most effective disinfectant against both Gram-positive and Gram-negative bacteria. This is the first study that compared the agar dilution and broth microdilution methods to assess the antimicrobial activity of QACs. The study demonstrated the need to standardize method that would be used in evaluating QACs antimicrobial properties in the future.

  4. Inhibition of Aspergillus flavus on agar media and brown rice cereal bars using cold atmospheric plasma treatment.

    PubMed

    Suhem, Kitiya; Matan, Narumol; Nisoa, Mudtorlep; Matan, Nirundorn

    2013-02-01

    This study aimed to optimize the operating parameters of cold atmospheric plasma treatment to inhibit the growth of Aspergillus flavus on agar media and brown rice cereal bars. The effects of argon plasma jet treatment on the growth of A. flavus on malt extract agar (MEA) at powers of 20 W and 40 W with exposure times at 5, 15 and 25 min were studied using response surface methodology (RSM) with a central composite face-centered (CCF) design. Multiple regression analysis indicated that plasma treatment at 40 W for 25 min is most effective for inhibiting growth of A. flavus on the agar medium. On brown rice cereal bars, plasma powered at 40 W for 20 min was capable of giving protection against A. flavus growth for up to 20 days under storage conditions of 25°C and 100% RH. These results demonstrated the potential of cold atmospheric plasma jet treatment to control mold growth on various food products.

  5. Antimicrobial susceptibility of Erysipelothrix rhusiopathiae isolated from pigs in Southern Japan with a modified agar dilution method.

    PubMed

    Chuma, Takehisa; Kawamoto, Toshio; Shahada, Francis; Fujimoto, Hideki; Okamoto, Karoku

    2010-05-01

    The determination of antimicrobial minimum inhibitory concentration (MIC) in Erysipelothrix rhusiopathiae by using the agar dilution method has not been covered by the Clinical and Laboratory Institute (CLSI). Only the broth microdilution method has been outlined. This report describes a modification of the agar dilution procedure for E. rhusiopathiae using Trypto-soy agar supplemented with 0.1% Tween 80 and incubation in ambient air at 37 degrees C for 24 hr. The MICs of the assay were in agreement with those of the broth microdilution method recommended by the CLSI. Antimicrobial susceptibility test was performed using this method for 149 E. rhusiopathiae isolates from 2 meat processing plants in Kagoshima Prefecture during the period of April 2004 to March 2005. The number of strains resistant to oxytetracycline, erythromycin, lincomycin, ofloxacin and enrofloxacin were 56 (37.6%), 4 (2.7%), 18 (12.1%), 21 (14.1%) and 19 (12.8%), respectively. All strains were susceptible to ampicillin.

  6. Enhanced chlorine resistance of tap water-adapted Legionella pneumophila as compared with agar medium-passaged strains.

    PubMed

    Kuchta, J M; States, S J; McGlaughlin, J E; Overmeyer, J H; Wadowsky, R M; McNamara, A M; Wolford, R S; Yee, R B

    1985-07-01

    Previous studies have shown that bacteria maintained in a low-nutrient "natural" environment such as swimming pool water are much more resistant to disinfection by various chemical agents than strains maintained on rich media. In the present study a comparison was made of the chlorine (Cl2) susceptibility of hot-water tank isolates of Legionella pneumophila maintained in tap water and strains passaged on either nonselective buffered charcoal-yeast extract or selective differential glycine-vancomycin-polymyxin agar medium. Our earlier work has shown that environmental and clinical isolates of L. pneumophila maintained on agar medium are much more resistant to Cl2 than coliforms are. Under the present experimental conditions (21 degrees C, pH 7.6 to 8.0, and 0.25 mg of free residual Cl2 per liter, we found the tap water-maintained L. pneumophila strains to be even more resistant than the agar-passaged isolates. Under these conditions, 99% kill of tap water-maintained strains of L. pneumophila was usually achieved within 60 to 90 min compared with 10 min for agar-passaged strains. Samples from plumbing fixtures in a hospital yielded legionellae which were "super"-chlorine resistant when assayed under natural conditions. After one agar passage their resistance dropped to levels of comparable strains which had not been previously exposed to additional chlorination. These studies more closely approximate natural conditions than our previous work and show that tap water-maintained L. pneumophila is even more resistant to Cl2 than its already resistant agar medium-passaged counterpart.

  7. In vitro anti-Helicobacter pylori potential of methanol extract of Allium ascalonicum Linn. (Liliaceae) leaf: susceptibility and effect on urease activity.

    PubMed

    Adeniyi, Bolanle A; Anyiam, Festus M

    2004-05-01

    The crude methanol extract of the leaf of Allium ascalonicum was screened in vitro against fi ve strains of Helicobacter pylori (Hp) (ATCC 24376, UCH 97001, UCH 97009, UCH 98026 and UCH 99039) for antibacterial activity by the agar diffusion method in Mueller-Hinton agar supplemented with de fi brinated horse blood. All the strains were inhibited by the extract to varying degrees. The minimum inhibitory concentrations (MICs) of the extract against all the tested strains ranged from 6.25 to 12.5 mg/mL. The effects of increasing concentrations of the extract on the urease activity of three of the Helicobacter pylori strains were investigated further. The results showed that increasing the concentration of the extract decreased the urease activity of all the strains tested. Phytochemical screening of the plant showed that it contains alkaloids, cardiac glycosides and saponins. The anti-Hp activity observed is discussed in relation to the chemical constituents reportedly isolated from these plants and their traditional uses. The result of this work suggests that Allium ascalonicum has some therapeutic potential against Helicobacter pylori infection, which could be explored for patients with gastroduodenal disorders.

  8. Prevalence, Antibiogram and Molecular Characterization of Comunity-Acquired Methicillin-Resistant Staphylococcus Aureus in AWKA, Anambra Nigeria

    PubMed Central

    Ike, Blessing; Ugwu, Malachy C.; Ikegbunam, Moses N.; Nwobodo, David; Ejikeugwu, Chika; Gugu, Thaddeus; Esimone, Charles O.

    2016-01-01

    Objectives: This study evaluated the prevalence, antibiogram and molecular features of CA-MRSA in Awka, Nigeria. Methods: Confirmation of MRSA was done by testing resistance to oxacillin (1µg), cloxacillin (5µg) and cefoxitin (30µg) on sterile Mueller Hinton agar supplemented with 4% sodium chloride. The MRSA strains were subjected to antimicrobial susceptibility testing using Kirby-Bauer disc diffusion method. Minimum inhibitory concentration was determined using agar dilution method. Penicillin binding protein 2a was detected through rapid latex agglutination assay while mecA gene was detected by polymerase chain reaction. A total of 142 S. aureus isolates were obtained from 261 samples sourced from Staff, students and fomites of the Faculty of Pharmaceutical Sciences Result: The overall prevalence of MRSA was 22.6%. The carriage rate was higher in females (56.5%) than male (43.5%) and was highest in individuals of 20-30 years of age (57.65%). The MIC of the oxacillin sodium salt ranged from 4-32 μg/ml. The multi-antibiotic resistance indices show that 53.4% had Multiple Antibiotic Resistance Indexing (MARI) higher than 0.2. Penicillin binding protein 2a was detected in 8.4% of MRSA isolates, all from nasal carriage while mecA gene was detected in 5 of isolates. Conclusion: This study showed a very high prevalence of MRSA carriage among studied subjects. PMID:28217194

  9. [Status of emerging drug resistance in Shiga toxin-producing Escherichia coli in Japan during 1996: a minireview].

    PubMed

    Yamamoto, T; Wakisaka, N

    1998-10-01

    A total of 192 Shiga toxin-producing Escherichia coli (STEC) strains isolated from the 1996 episodes in Japan were tested for their in vitro susceptibilities to 41 antimicrobial agents. Drug resistance was found with kanamycin, tetracycline, nalidixic acid, ampicillin, streptomycin, sulfamethoxazole, and fosfomycin. The expression of fosfomycin resistance was greatly dependent on culture conditions and resistance was detected (e.g.) when Mueller-Hinton agar or nutrient agar supplemented with horse blood (or glucose-6-phosphate) was used as test media. All the STEC strains belonging to serotype O26 exhibited fosfomycin resistance. Multiple drug-resistant strains spread 8 of 18 prefectures examined. Out of eleven O157: H7 outbreaks, only one outbreak revealed infections due to multiple drug-resistant strains which carried an R plasmid. Tetracycline, streptomycin, and sulfamethoxazole resistance, which was previously described with O157: H7 strains isolated from a large outbreak as well as sporadic cases in the United States, were also found in Japan with human and bovine isolates (but not with porcine isolates). In contrast, the STEC strains were highly susceptible to newer quinolones, cephems, trimethoprim, gentamicin, and azithromycin. No drug resistance was observed with dibekacin and minocycline.

  10. Comparison of the antimicrobial activity of direct pulp-capping materials: Mineral trioxide aggregate-Angelus and Biodentine

    PubMed Central

    Özyürek, Taha; Demiryürek, Ebru Özsezer

    2016-01-01

    Purpose: To compare the antimicrobial activity of the tricalcium silicate-based Biodentine (BD) and mineral trioxide aggregate (MTA)-Angelus cement with the aid of agar diffusion test. Materials and Methods: Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, and Enterococcus faecium were inoculated in the Brucella liquid medium and were incubated at 37°C for 24 h. Thereafter, 100 >μl of the liquid culture of bacteria inoculated in the Mueller-Hinton agar with spread plate technique. Petri plates were dried in room temperature. For every microorganism, 3 petri plates were prepared (12 in total). In the medium, in every petri plate, 2 holes with 5 mm diameter and 2 mm depth were made. Afterward, BD and MTA-Angelus were filled into these holes under aseptic conditions according to the instructions of the manufacturing company. Then, the plates were kept in the incubator at 37°C for 24 h, and the diameters of the inhibition zones were measured with a digital caliper. Results: Inhibition zones formed by BD against E. coli and S. aureus were significantly larger than the zones formed by MTA-Angelus (P < 0.05). However, the inhibition zones formed by MTA-Angelus against P. aureus and E. faecium were larger than the zones formed by BD (P < 0.05). Conclusion: Within the limits of the present study, tricalcium silicate-based MTA-Angelus and BD have antimicrobial activity against E. coli, S. aureus, P. aureus, and E. faecium. PMID:27994321

  11. Antibacterial Activity and Fluoride Release of Glass-Ionomer Cement, Compomer and Zirconia Reinforced Glass-Ionomer Cement

    PubMed Central

    Kenchappa, Mallikarjuna; Bhayya, Deepak; Gupta, Shilpi; Saxena, Sudhanshu; Satyarth, Saurabh; Singh, Aishwarya; Gupta, Manoj

    2016-01-01

    Introduction The cariostatic property of glass ionomer cement (GIC) stems from its ability to release fluoride into the oral environment. Recently, zirconia reinforced GIC has been launched which promises the protective benefits of glass ionomer while completely eliminating the hazard of mercury. Aim To evaluate invitro antibacterial activity and fluoride release from two conventional glass ionomer cements (GC II and GC IX), compomer (Compoglass) and a zirconia reinforced glass ionomer cement (Zirconomer). Materials and Methods The antibacterial activity of the cement specimens was evaluated against Streptococcus mutans using the agar inhibition test. Zone of inhibition on Mueller-Hinton agar plates was measured after 48 hours. The fluoride release from the cement specimens in ppm were measured at day 1, 7, 14 and 21 using a fluoride ion selective electrode. Data was analysed using one-way and two-way analysis of variance (ANOVA) followed by LSD post-hoc test. A p-value <0.05 was considered statistically significant. Results Statistically significant largest zone of inhibition was observed with Zirconomer. Also, significant differences were seen in fluoride release of different materials. At all the time intervals maximum fluoride release was observed with Zirconomer and minimum with Compoglass. Conclusion This invitro investigation has revealed that zirconia reinforced GIC (Zirconomer) had maximum antibacterial activity against S.mutans and fluoride release. PMID:27190961

  12. [Is it necessary to know which workers are carriers of MRSA in contact with cancer patients?].

    PubMed

    García-Lozano, Tomás; Egido, Adoración; Contel, Elena; Picón, María Isabel; Martínez, María Ángeles; Aznar, Eduardo

    2012-12-01

    Our objective was to determine the prevalence of methicillin-resistant Staphylococcus aureus in workers who had direct contact with oncologic patients infected with MRSA and admitted to the intensive care unit of the Valencian Institute of Oncology. A study of prevalence of MRSA colonization of 62 workers was performed. Samples were taken from nose and pharynx in each of the workers. After 24 hours of incubation in Amies transport medium Viscose (Eurotubo®), 124 samples were seeded (N = 124) in chocolate agar agar, MRSA II and BHI broth (Brain Heart Infusion). Those colonies that were identified by Gram stain gram-positive cocci in clusters available, catalase positive and coagulase positive were processed for study of sensitivity by Kirby-Bauer method and screening test for methicillin (10μg of Oxoid®) on Mueller-Hinton (Becton-Dickinson®, BD), supplemented with NaCl (2%). Those confirmed MRSA isolates, he returned to perform sensitivity study by microdilution (MicroScan®, Siemens) to determine the MIC (mg/L). The prevalence of methicillin-resistant Staphylococcus aureus (MRSA) was 1.61% (1) and 12.90% (8) for methicillin-sensitive Staphylococcus aureus (MSSA), from nostrils. The measures implemented were: nasal application of mupirocin to the worker colonized control isolation measures in infected patients and indoctrination of the personnel involved.

  13. Enhancement by sodium chloride of the selectivity of thiosulfate citrate bile salts sucrose agar for isolating Vibrio cholerae biotype El Tor.

    PubMed Central

    Morris, G K; DeWitt, W E; Gangarosa, E J; McCormack, W M

    1976-01-01

    In this study we utilized the salt-tolerant characteristics of vibrios to develop a more selective medium by addition of NaCl to thiosulfate citrate bile salts sucrose (TCBS) agar. The effect of adding salt to TCBS agar varied greatly among brands of TCBS agar and between lots of the same brand. The addition of salt at concentrations as high as 1.5% (2.5% total NaCl) caused the inhibition of growth of three species of commonly encountered normal bowel flora and one strain of classical Vibrio cholerae but did not compromise the use of TCBS agar for isolation of V. cholerae biotype El Tor. PMID:965476

  14. Effects of immersion disinfection of agar-alginate combined impressions on the surface properties of stone casts.

    PubMed

    Iwasaki, Yukiko; Hiraguchi, Hisako; Iwasaki, Eriko; Yoneyama, Takayuki

    2016-01-01

    This study investigated the effects of disinfection of agar-alginate combined impressions on the surface properties of the resulting stone casts. Two brands of cartridge-form agar impression material and one alginate impression material were used. Agar-alginate combined impressions of smooth glass plates were prepared. The impressions were immersed in 0.55% ortho-phthalaldehyde solution or 0.5% sodium hypochlorite solution for 1, 3, 5 and 10 min. A stone cast made with an impression that had not been immersed was prepared as a control. The surface roughness (Ra) of the stone casts was measured, and the cast surfaces were observed by SEM. Immersion of agar-alginate combined impressions in 0.5% sodium hypochlorite solution for up to 10 min had no serious adverse effects on the surface properties of the stone casts. In contrast, even 1 min of immersion in 0.55% ortho-phthalaldehyde solution caused deterioration of the cast surface properties.

  15. Choline chloride based ionic liquid analogues as tool for the fabrication of agar films with improved mechanical properties

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In the present paper, we test the suitability of Choline-Cl/urea (DES-U) and Choline-Cl/glycerol (DES-G) eutectic mixtures at 1:2 molar ratios for the production of agar biodegradable films. A three-step process is proposed: pre-solubilization of polymer in DES followed by compression-molding and s...

  16. Campylobacter in broiler slaughter samples assessed by direct count on mCCDA and Campy-Cefex agar.

    PubMed

    Gonsalves, Camila Cristina; Borsoi, Anderlise; Perdoncini, Gustavo; Rodrigues, Laura Beatriz; do Nascimento, Vladimir Pinheiro

    2016-01-01

    Campylobacter spp. cause foodborne illnesses in humans primarily through the consumption of contaminated chicken. The aim of this study was to evaluate the United States Department of Agriculture's (USDA) recommended methodology, protocol MLG 41.02, for the isolation, identification and direct plate counting of Campylobacter jejuni and C. coli samples from the broiler slaughtering process. A plating method using both mCCDA and Campy-Cefex agars is recommended to recover Campylobacter cells. It is also possible to use this method in different matrices (cloacal swabs and water samples). Cloacal swabs, samples from pre-chiller and post-chiller carcasses and samples of pre-chiller, chiller and direct supply water were collected each week for four weeks from the same flock at a slaughterhouse located in an abattoir in southern Brazil. Samples were analyzed to directly count Campylobacter spp., and the results showed a high frequency of Campylobacter spp. on Campy-Cefex agar. For the isolated species, 72% were identified as Campylobacter jejuni and 38% as Campylobacter coli. It was possible to count Campylobacter jejuni and Campylobacter coli from different samples, including the water supply samples, using the two-agar method. These results suggest that slaughterhouses can use direct counting methods with both agars and different matrices as a monitoring tool to assess the presence of Campylobacter bacteria in their products.

  17. Intelligent pH indicator film composed of agar/potato starch and anthocyanin extracts from purple sweet potato.

    PubMed

    Choi, Inyoung; Lee, Jun Young; Lacroix, Monique; Han, Jaejoon

    2017-03-01

    A new colorimetric pH indicator film was developed using agar, potato starch, and natural dyes extracted from purple sweet potato, Ipomoea batatas. Both agar and potato starch are solid matrices used to immobilize natural dyes, anthocyanins. The ultraviolet-visible (UV-vis) spectrum of anthocyanin extract solutions and agar/potato starch films with anthocyanins showed color variations to different pH values (pH 2.0-10.0). Fourier transform infrared (FT-IR) and UV-vis region spectra showed compatibility between agar, starch, and anthocyanin extracts. Color variations of pH indicator films were measured by a colorimeter after immersion in different pH buffers. An application test was conducted for potential use as a meat spoilage sensor. The pH indicator films showed pH changes and spoilage point of pork samples, changing from red to green. Therefore, the developed pH indicator films could be used as a diagnostic tool for the detection of food spoilage.

  18. [An observation on the histological structure of Oncomelania hupensis soft tissue by agar-paraffin double-embedding method].

    PubMed

    Tan, Ping; Zhang, Jie; Li, Qing; Yu, Zhi-jun

    2014-12-01

    In order to study the histological structure of Oncomelania hupensis soft tissue, the fixed soft tissues of O. hupensis were pre-embedded in the agar and made blocks, then dehydrated, transparentized, immersed in paraffin, sectioned, and stained with haematoxylin-eosin (HE). Permanent slides of O. hupensis soft tissue were obtained. The histological structure of soft tissues was clear under the microscope.

  19. Thermal inactivation and sublethal injury kinetics of Salmonella enterica and Listeria monocytogenes in broth versus agar surface.

    PubMed

    Wang, Xiang; Devlieghere, Frank; Geeraerd, Annemie; Uyttendaele, Mieke

    2017-02-21

    The objective of the present study was to compare the thermal inactivation and sublethal injury kinetics of Salmonella enterica and Listeria monocytogenes in broth (suspended cells) and on solid surface (agar-seeded cells). A 3-strain cocktail of S. enterica or L. monocytogenes inoculated in broth or on agar was subjected to heating in a water bath at various set temperatures (55.0, 57.5 and 60.0°C for S. enterica and 60.0, 62.5 and 65°C for L. monocytogenes). The occurrence of sublethally injured cells was determined by comparing enumerations on nonselective (TSAYE) and selective (XLD or ALOA) media. Results showed that the inactivation curves obtained from selective media were log-linear, and significant shoulders (p<0.05) were observed on some of the inactivation curves from TSAYE media. The D-values derived from the total population were higher than those from the uninjured cells. Generally, cells on agar surface exhibited higher heat resistance than those in broth. For S. enterica, cell injury increased with the exposure time, no difference was observed when treated at temperatures from 55.0 to 60.0°C, while for L. monocytogenes, cell injury increased significantly with heating time and treatment temperature (from 60.0 to 65°C). Moreover, the degree of sublethal injury affected by thermal treatment in broth or on agar surface depended upon the target microorganism. Higher proportions of injured S. enterica cells were observed for treatment in broth than on agar surface, while the opposite was found for L. monocytogenes. The provided information may be used to assess the efficacy of thermal treatment processes on surfaces for inactivation of S. enterica and L. monocytogenes, and it provides insight into the sublethally injured survival state of S. enterica and L. monocytogenes treated in liquid or on solid food.

  20. Control of Drug Diffusion Behavior of Xanthan and Locust Bean Gum Gel by Agar Gel.

    PubMed

    Hishikawa, Yoshihiro; Kakino, Yukari; Tsukamoto, Hoshi; Tahara, Kohei; Onodera, Risako; Takeuchi, Hirofumi

    2016-01-01

    Oral gel formulations are known as easy to administer drug products for patients who have problems taking drugs including those with conditions such as dysphagia. In addition, there are numerous commercially available oral gel products, most of which are immediate-release formulation that release their pharmaceutical ingredient content by diffusion. This study is focused on developing oral gel formulations that reduce the dosing frequency and dosage compared to the conventional types. This is with the aim of facilitating the use of gel formulations for producing pharmaceutical agents with different dose regimens, thereby enhancing patient convenience. Here, we used naturally derived high-molecular-weight agar (Ag), xanthan gum (Xa), and locust bean gum (Lo) as gel bases to prepare a variety of gel membranes, and evaluated the diffusion coefficient of the model substances. The result revealed that the Ag content in the Xa-Lo combination gel concentration-dependently increased the diffusion coefficient. Moreover, these findings were applied in an attempt to mask the taste of intensely bitter levofloxacin. The results indicated that the Xa-Lo combination gel exhibited a significantly superior masking effect to that of the Ag gel. This study demonstrates the feasibility of using oral gel formulations to modulate the controlled-release functionality of pharmaceutical agents.

  1. Characterisation of Elastic and Acoustic Properties of an Agar-Based Tissue Mimicking Material.

    PubMed

    Brewin, M P; Birch, M J; Mehta, D J; Reeves, J W; Shaw, S; Kruse, C; Whiteman, J R; Hu, S; Kenz, Z R; Banks, H T; Greenwald, S E

    2015-10-01

    As a first step towards an acoustic localisation device for coronary stenosis to provide a non-invasive means of diagnosing arterial disease, measurements are reported for an agar-based tissue mimicking material (TMM) of the shear wave propagation velocity, attenuation and viscoelastic constants, together with one dimensional quasi-static elastic moduli and Poisson's ratio. Phase velocity and attenuation coefficients, determined by generating and detecting shear waves piezo-electrically in the range 300 Hz-2 kHz, were 3.2-7.5 ms(-1) and 320 dBm(-1). Quasi-static Young's modulus, shear modulus and Poisson's ratio, obtained by compressive or shear loading of cylindrical specimens were 150-160 kPa; 54-56 kPa and 0.37-0.44. The dynamic Young's and shear moduli, derived from fitting viscoelastic internal variables by an iterative statistical inverse solver to freely oscillating specimens were 230 and 33 kPa and the corresponding relaxation times, 0.046 and 0.036 s. The results were self-consistent, repeatable and provide baseline data required for the computational modelling of wave propagation in a phantom.

  2. Theoretical and experimental NMR studies on muscimol from fly agaric mushroom (Amanita muscaria)

    NASA Astrophysics Data System (ADS)

    Kupka, Teobald; Wieczorek, Piotr P.

    2016-01-01

    In this article we report results of combined theoretical and experimental NMR studies on muscimol, the bioactive alkaloid from fly agaric mushroom (Amanita muscaria). The assignment of 1H and 13C NMR spectra of muscimol in DMSO-d6 was supported by additional two-dimensional heteronuclear correlated spectra (2D NMR) and gauge independent atomic orbital (GIAO) NMR calculations using density functional theory (DFT). The effect of solvent in theoretical calculations was included via polarized continuum model (PCM) and the hybrid three-parameter B3LYP density functional in combination with 6-311++G(3df,2pd) basis set enabled calculation of reliable structures of non-ionized (neutral) molecule and its NH and zwitterionic forms in the gas phase, chloroform, DMSO and water. GIAO NMR calculations, using equilibrium and rovibrationally averaged geometry, at B3LYP/6-31G* and B3LYP/aug-cc-pVTZ-J levels of theory provided muscimol nuclear magnetic shieldings. The theoretical proton and carbon chemical shifts were critically compared with experimental NMR spectra measured in DMSO. Our results provide useful information on its structure in solution. We believe that such data could improve the understanding of basic features of muscimol at atomistic level and provide another tool in studies related to GABA analogs.

  3. A selective chromogenic agar that distinguishes Bacillus anthracis from Bacillus cereus and Bacillus thuringiensis.

    PubMed

    Juergensmeyer, Margaret A; Gingras, Bruce A; Restaino, Lawrence; Frampton, Elon W

    2006-08-01

    A selective and differential plating medium, R & F anthracis chromogenic agar (ACA), has been developed for isolating and identifying presumptive colonies of Bacillus anthracis. ACA contains the chromogenic substrate 5-bromo-4-chloro-3-indoxyl-choline phosphate that upon hydrolysis yields teal (blue green) colonies indicating the presence of phosphatidylcholine-specific phospholipase C (PC-PLC) activity. Among seven Bacillus species tested on ACA, only members of the Bacillus cereus group (B. anthracis, B. cereus, and B. thuringiensis) produced teal colonies (PC-PLC positive) having cream rings. Examination of colony morphology in 18 pure culture strains of B. anthracis (15 ATCC strains plus AMES-1-RIID, ANR-1, and AMED-RIID), with one exception, required 48 h at 35 to 37 degrees C for significant color production, whereas only 24 h was required for B. cereus and B. thuringiensis. This differential rate of PC-PLC synthesis in B. anthracis (due to the truncated plcR gene and PlcR regulator in B. anthracis) allowed for the rapid differentiation on ACA of presumptive colonies of B. anthracis from B. cereus and B. thuringiensis in both pure and mixed cultures. Effective recovery of B. anthracis from a variety of matrices having both high (soil and sewage) and low microbial backgrounds (cloth, paper, and blood) spiked with B. anthracis ANR-1 spores suggests the probable utility of ACA plating for B. anthracis recovery in a diversity of applications.

  4. Theoretical and experimental NMR studies on muscimol from fly agaric mushroom (Amanita muscaria).

    PubMed

    Kupka, Teobald; Wieczorek, Piotr P

    2016-01-15

    In this article we report results of combined theoretical and experimental NMR studies on muscimol, the bioactive alkaloid from fly agaric mushroom (Amanita muscaria). The assignment of (1)H and (13)C NMR spectra of muscimol in DMSO-d6 was supported by additional two-dimensional heteronuclear correlated spectra (2D NMR) and gauge independent atomic orbital (GIAO) NMR calculations using density functional theory (DFT). The effect of solvent in theoretical calculations was included via polarized continuum model (PCM) and the hybrid three-parameter B3LYP density functional in combination with 6-311++G(3df,2pd) basis set enabled calculation of reliable structures of non-ionized (neutral) molecule and its NH and zwitterionic forms in the gas phase, chloroform, DMSO and water. GIAO NMR calculations, using equilibrium and rovibrationally averaged geometry, at B3LYP/6-31G* and B3LYP/aug-cc-pVTZ-J levels of theory provided muscimol nuclear magnetic shieldings. The theoretical proton and carbon chemical shifts were critically compared with experimental NMR spectra measured in DMSO. Our results provide useful information on its structure in solution. We believe that such data could improve the understanding of basic features of muscimol at atomistic level and provide another tool in studies related to GABA analogs.

  5. Mercury and its bioconcentration factors in fly agaric (Amanita muscaria) from spatially distant sites in Poland.

    PubMed

    Falandysz, J; Lipka, K; Mazur, A

    2007-09-01

    Total mercury content has been determined in the fruiting bodies of fly agaric (Amanita muscaria) and topsoil layer (0-10 cm) collected from 14 spatially distant sites across Poland. Mercury was measured by cold-vapor atomic absorption spectroscopy (CV-AAS) after nitric acid (mushrooms) or nitric acid and sulfuric acid (soil) digestion of the samples. The caps, depending on the site, contained total mercury at mean concentrations from 0.24+/-0.13 to 1.4+/-0.6 microg/g dm (median 0.19-1.4 microg/g dm), and stalks from 0.18+/-0.06 to 0.71+/-0.26 microg/g dm (median 0.18-0.67 microg/g dm). An overall-mean the total mercury content for 204 caps and stalks was, respectively, 0.73+/-0.55 (0.05-3.3 microg/g dm) and 0.43+/-0.33 (0.09-2.3 microg/g dm).

  6. Comparison of CHROMagar Salmonella Medium and Hektoen Enteric Agar for Isolation of Salmonellae from Stool Samples

    PubMed Central

    Gaillot, Olivier; Di Camillo, Patrick; Berche, Patrick; Courcol, René; Savage, Colette

    1999-01-01

    CHROMagar Salmonella (CAS), a new chromogenic medium, was retrospectively compared to Hektoen enteric agar (HEA) with 501 Salmonella stock isolates and was then prospectively compared to HEA for the detection and presumptive identification of Salmonella spp. with 508 stool samples before and after enrichment. All stock cultures (100%), including cultures of H2S-negative isolates, yielded typical mauve colonies on CAS, while 497 (99%) isolates produced typical lactose-negative, black-centered colonies on HEA. Following overnight incubation at 37°C, a total of 20 Salmonella strains were isolated from the 508 clinical samples. Sensitivities for primary plating and after enrichment were 95% (19 isolates) and 100% (20 isolates), respectively, for CAS and 80% (16 isolates) and 100% (20 isolates), respectively, for HEA. The specificity of CAS (88.9%) was significantly higher than that of HEA (78.5%; P < 0.0001). On the basis of its good sensitivity and specificity, CAS medium can be recommended for use for primary plating when human stool samples are screened for Salmonella spp. PMID:9986847

  7. Usefulness of Candida ID2 agar for the presumptive identification of Candida dubliniensis.

    PubMed

    Eraso, Elena; Sahand, Ismail H; Villar-Vidal, María; Marcos, Cristina; Dolores Moragues, María; Madariaga, Lucila; Pontón, José; Quindós, Guillermo

    2006-11-01

    CHROMagar Candida and Candida ID2 are widely used for the isolation and presumptive identification of Candida spp. based on the color of the colonies on these two media. We have studied the usefulness of these chromogenic media for differentiating Candida dubliniensis from Candida albicans isolates. One hundred isolates of C. dubliniensis and 100 C. albicans isolates were tested on Candida ID2, CHROMagar Candida (CHROMagar), and CHROMagar Candida reformulated by BBL. CHROMagar Candida and CHROMagar Candida BBL did not allow a clear differentiation of the two species based upon the shade of the green color of C. dubliniensis colonies. However, on Candida ID2, all C. dubliniensis isolates produced turquoise blue colonies whereas 91% of C. albicans colonies were cobalt blue. The sensitivity and the specificity for differentiating between C. dubliniensis fromC. albicans on Candida ID2 were 100% and 91%, respectively; whereas on CHROMagar Candida these values were 63% and 89% and on CHROMagar Candida BBL they were 18% and 98%. Candida ID2 agar provides a simple and accurate laboratory approach for the identification and differentiation of C. dubliniensis on the basis of the colony color.

  8. Antimicrobial susceptibility of Brazilian Clostridium difficile strains determined by agar dilution and disk diffusion.

    PubMed

    Fraga, Edmir Geraldo; Nicodemo, Antonio Carlos; Sampaio, Jorge Luiz Mello

    2016-01-01

    Clostridium difficile is a leading cause of diarrhea in hospitalized patients worldwide. While metronidazole and vancomycin are the most prescribed antibiotics for the treatment of this infection, teicoplanin, tigecycline and nitazoxanide are alternatives drugs. Knowledge on the antibiotic susceptibility profiles is a basic step to differentiate recurrence from treatment failure due to antimicrobial resistance. Because C. difficile antimicrobial susceptibility is largely unknown in Brazil, we aimed to determine the profile of C. difficile strains cultivated from stool samples of inpatients with diarrhea and a positive toxin A/B test using both agar dilution and disk diffusion methods. All 50 strains tested were sensitive to metronidazole according to CLSI and EUCAST breakpoints with an MIC90 value of 2μg/mL. Nitazoxanide and tigecycline were highly active in vitro against these strains with an MIC90 value of 0.125μg/mL for both antimicrobials. The MIC90 were 4μg/mL and 2μg/mL for vancomycin and teicoplanin, respectively. A resistance rate of 8% was observed for moxifloxacin. Disk diffusion can be used as an alternative to screen for moxifloxacin resistance, nitazoxanide, tigecycline and metronidazole susceptibility, but it cannot be used for testing glycopeptides. Our results suggest that C. difficile strains from São Paulo city, Brazil, are susceptible to metronidazole and have low MIC90 values for most of the current therapeutic options available in Brazil.

  9. Development and validation of a microbiological agar assay for determination of cefuroxime sodium in pharmaceutical preparations.

    PubMed

    Schmidt, Cleber A; Agarrayua, Danielle A; Laporta, Luciane V; Machado, Jaison C; Manfio, Maria L; Bittencourt, Celso F

    2009-06-01

    Cefuroxime (CFU) is a semi-synthetic cephalosporin with a relatively broad-spectrum antimicrobial activity, and belongs to the second generation of cephalosporins. Regarding the quality control of medicines, a validated microbiological assay for determination of cefuroxime sodium in pharmaceutical formulations has not been reported yet. With this purpose, this paper reports the development and validation of a simple, sensitive, accurate and reproducible agar diffusion method to quantify CFU sodium in injectable formulations. The assay is based on the inhibitory effect of CFU upon the strain of Staphylococcus aureus ATCC 6538P used as test microorganism. The results were treated statistically by analysis of variance and were found to be linear (r=0.9998) in the selected range of 8.0-32.0 microg/ml; precise [repeatability: relative standard deviation (RSD)=1.56%; intermediate precision: between-day RSD=1.27%; between analyst RSD=1.13%] and accurate (101.58%). The bioassay specificity was studied by evaluation of degraded sample at 50 degrees C with analysis at 0, 24 and 48 h in parallel with the pharmacopeial liquid chromatography method for CFU. The results demonstrated the validity of the proposed bioassay, which allows reliable quantitation of CFU sodium in pharmaceutical samples and therefore can be used as a useful alternative methodology for the routine quality control of this medicine.

  10. Dichromated agar: a promising doped biocopolymer for real time holographic recording

    NASA Astrophysics Data System (ADS)

    Bolte, Michèle; Israëli, Yaël; Rivaton, Agnès; Lessard, Roger A.

    2006-09-01

    Agar is a natural polysaccharide which, when doped with dichromate ammonium, can be considered as a promising light sensitive material used for real time hologram recording. The volume transmission gratings were recorded with a Kypton laser at 413 nm and they were read in real-time with a He/Ne laser at 632.8 nm contrary to dichromated gelatin. The so obtained holograms formed were phase holograms due to a refraction index modulation. The optimisation of chemical and physical parameters was investigated in order to form high quality holograms. It was demonstrated the crucial role played by the remaining water in the final film on the value of the diffraction efficiency. In the optimal conditions, a maximum diffraction efficiency of 37 % was attained. Both on-off experiments and the storage of the exposed materials at room temperature and in the dark reveal that the holograms were stable. An attempt to rationalize the set of results in terms of chemical structure of the polymeric matrix and of its ability to stabilize chromium (V) is presented.

  11. Physico-chemical and microstructural properties of fish gelatin/agar bio-based blend films.

    PubMed

    Mohajer, Setareh; Rezaei, Masoud; Hosseini, Seyed Fakhreddin

    2017-02-10

    This study was conducted with the aim of improving the physico-chemical properties of fish gelatin (FG) based films. For this purpose, FG was blended with agar (AG) in different compositions to acquire biodegradable films (100:0, 80:20, 60:40, 50:50 & 0:100, FG:AG). The obtained results showed that the AG addition strongly increased the film rigidity and resistance to fracture, while reducing the film stretchability, mainly at 50FG: 50AG ratio. AG incorporation greatly reduced the water vapor permeability (WVP) and solubility of gelatin films, as this decline for the blend film with a 50:50 ratio of biopolymers has been about 41% and 66%, respectively (p<0.05). Additional advantages of AG inclusion to FG films are the reduction of the UV-transmittance. Both polymers showed good compatibility, as demonstrated by scanning electron microscopy (SEM) and atomic force microscopy (AFM) images. Therefore, the blend composition influenced the properties of FG/AG bio-based films.

  12. Development and Validation of a Microbiological Agar Assay for Determination of Orbifloxacin in Pharmaceutical Preparation

    PubMed Central

    Cazedey, Edith C. L.; Salgado, Hérida R. N.

    2011-01-01

    Orbifloxacin is a fluoroquinolone with broad-spectrum antimicrobial activity, and belongs to the third generation of quinolones. Regarding the quality control of medicines, a validated microbiological assay for determination of orbifloxacin in pharmaceutical formulations has not as yet been reported. For this purpose, this paper reports the development and validation of a simple, sensitive, accurate and reproducible agar diffusion method to quantify orbifloxacin in tablet formulations. The assay is based on the inhibitory effect of orbifloxacin upon the strain of Staphylococcus aureus ATCC 25923 used as test microorganism. The results were treated statistically by analysis of variance and were found to be linear (r = 0.9992) in the selected range of 16.0–64.0 μg/mL, precise with relative standard deviation (RSD) of repeatability intraday = 2.88%, intermediate precision RSD = 3.33%, and accurate (100.31%). The results demonstrated the validity of the proposed bioassay, which allows reliable orbifloxacin quantitation in pharmaceutical samples and therefore can be used as a useful alternative methodology for the routine quality control of this medicine. PMID:24310597

  13. Comparison of sorbitol MacConkey and hemorrhagic coli agars for recovery of Escherichia coli O157:H7 from brie, ice cream, and whole milk.

    PubMed

    Hammack, T S; Feng, P; Amaguaña, R M; June, G A; Sherrod, P S; Andrews, W H

    1997-01-01

    The relative efficacies of hemorrhagic coli (HC) agar and several formulations of sorbitol MacConkey (SorMac) agar, with and without 0.1% (w/v) 4-methyllumbelliferyl-beta-D-glucuronide (MUG), in recovering unstressed and heat-stressed Escherichia coli O157:H7 from Brie cheese, ice cream, and whole milk were determined. Recovery of unstressed E. coli O157:H7 was determined quantitatively by spread-plating diluted samples onto different agars and performing plate counts. Recovery of stressed E. coli O157:H7 was determined qualitatively by enriching samples in modified trypticase soy broth, streaking the incubated enrichments, and isolating E. coli O157:H7 colonies from the agars. HC agar and the SorMac agar formulations did not differ significantly in their ability to recover unstressed E. coli O157:H7 from ice cream and whole milk; however, HC agar recovered significantly more unstressed E. coli O157:H7 from Brie cheese than did the SorMac agar formulations. Bacteriological Analytical Manual and Oxoid SorMac agar formulations made from individual ingredients, did not differ significantly in recovering unstressed E. coli O157:H7 from Brie cheese. The efficiency of the commercially available Oxoid SorMac agar could not be determined because of overgrowth by indigenous microflora. HC and SorMac agars did not differ significantly in recovering stressed E. coli O157:H7 from Brie cheese, ice cream, and whole milk. MUG had no apparent effect on recovery of either stressed or unstressed E. coli O157:H7 from the dairy foods examined.

  14. Multilaboratory evaluation of disk diffusion antimicrobial susceptibility testing of Neisseria meningitidis isolates.

    PubMed

    Jorgensen, James H; Crawford, Sharon A; Fulcher, Letitia C; Glennen, Anita; Harrington, Susan M; Swenson, Jana; Lynfield, Ruth; Murray, Patrick R; Tenover, Fred C

    2006-05-01

    In 2005, the Clinical and Laboratory Standards Institute published MIC interpretive criteria for 13 antimicrobial agents used for either therapy or prophylaxis of Neisseria meningitidis infections. The MIC method includes the use of lysed horse blood-supplemented Mueller-Hinton broth with incubation in 5% CO2 for 20 to 24 h. Since some clinical laboratories might prefer the option of disk diffusion testing for infrequently encountered isolates a multicenter collaborative study was conducted to evaluate the reproducibility of a disk diffusion method for testing isolates of N. meningitidis. Interpretive criteria were developed for 12 antimicrobial agents. Four laboratories tested a common collection of 50 meningococcal strains and then tested 25 unique isolates per laboratory. Isolates were tested using Mueller-Hinton sheep blood agar plates incubated for 20 to 24 h in 5% CO2; they were also tested by the reference broth microdilution method in parallel. Pooling of the MIC and disk diffusion data from the common and unique isolates provided a sufficient sample size to develop susceptible, intermediate, and resistant zone diameter interpretive criteria using the error rate-bounded method for the following agents: chloramphenicol, trimethoprim-sulfamethoxazole, ciprofloxacin, and rifampin. Due to the lack of resistant strains at the present time, "susceptible only" interpretive criteria were proposed for cefotaxime, ceftriaxone, meropenem, azithromycin, and minocycline. The numbers of minor interpretive errors with penicillin and ampicillin disk tests were unacceptably high and precluded recommended testing of those agents by the disk method. However, amdinocillin, an agent that preferentially binds to the altered penicillin binding protein responsible for diminished penicillin susceptibility, has potential utility as a surrogate screening reagent for ampicillin resistance. A disk diffusion breakpoint was derived for nalidixic acid to serve as a surrogate marker for

  15. Equivalency testing of TTC Tergitol 7 agar (ISO 9308-1:2000) with five culture media for the detection of E. coli in water samples in Greece.

    PubMed

    Mavridou, A; Smeti, E; Mandilara, G; Mandilara, G; Boufa, P; Vagiona-Arvanitidou, M; Vantarakis, A; Vassilandonopoulou, G; Pappa, O; Roussia, V; Tzouanopoulos, A; Livadara, M; Aisopou, I; Maraka, V; Nikolaou, E; Mandilara, G

    2010-01-01

    In this study ten laboratories in Greece compared the performance of reference method TTC Tergitol 7 Agar (with the additional test of beta-glucuronidase production) with five alternative methods, to detect E. coli in water, in line with European Water Directive recommendations. The samples were prepared by spiking drinking water with sewage effluent following a standard protocol. Chlorinated and non-chlorinated samples were used. The statistical analysis was based on the mean relative difference of confirmed counts and was performed in line with ISO 17994. The results showed that in total, three of the alternative methods (Chromocult Coliform agar, Membrane Lauryl Sulfate agar and Trypton Bilex-glucuronidase medium) were not different from TTC Tergitol 7 agar (TTC Tergitol 7 agar vs Chromocult Coliform agar, 294 samples, mean RD% 5.55; vs MLSA, 302 samples, mean RD% 1; vs TBX, 297 samples, mean RD% -2.78). The other two alternative methods (Membrane Faecal coliform medium and Colilert 18/ Quantitray) gave significantly higher counts than TTC Tergitol 7 agar (TTC Tergitol 7 agar vs MFc, 303 samples, mean RD% 8.81; vs Colilert-18/Quantitray, 76 samples, mean RD% 18.91). In other words, the alternative methods generated performance that was as reliable as, or even better than, the reference method. This study will help laboratories in Greece overcome culture and counting problems deriving from the EU reference method for E. coli counts in water samples.

  16. Use of agar diffusion assay to evaluate bactericidal activity of formulations of alkaline salts of fatty acids against bacteria associated with poultry processing

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The agar diffusion assay was used to examine antibacterial activity of alkaline salts of fatty acids (FA). Wells in agar media seeded with bacteria were filled with FA-potassium hydroxide (KOH) solutions, plates were incubated, and zones of inhibition were measured. The relationship between bacteric...

  17. Chromium and zinc uptake by algae Gelidium and agar extraction algal waste: kinetics and equilibrium.

    PubMed

    Vilar, Vítor J P; Botelho, Cidália M S; Boaventura, Rui A R

    2007-11-19

    Biosorption of chromium and zinc ions by an industrial algal waste, from agar extraction industry has been studied in a batch system. This biosorbent was compared with the algae Gelidium itself, which is the raw material for agar extraction, and the industrial waste immobilized with polyacrylonitrile (composite material). Langmuir and Langmuir-Freundlich equilibrium models describe well the equilibrium data. The parameters of Langmuir equilibrium model at pH 5.3 and 20 degrees C were for the algae, q(L)=18 mg Cr(III)g(-1) and 13 mgZn(II)g(-1), K(L) = 0.021l mg(-1)Cr(III) and 0.026l mg(-1) Zn(II); for the algal waste, q(L)=12 mgCr(III)g(-1) and 7mgZn(II)g(-1), K(L)=0.033lmg(-1) Cr(III) and 0.042l mg(-1) Zn(II); for the composite material, q(L) = 9 mgCr(III)g(-1) and 6 mgZn(II)g(-1), K(L)=0.032l mg(-1)Cr(III) and 0.034l mg(-1)Zn(II). The biosorbents exhibited a higher preference for Cr(III) ions and algae Gelidium is the best one. The pseudo-first-order Lagergren and pseudo-second-order models fitted well the kinetic data for the two metal ions. Kinetic constants and equilibrium uptake concentrations given by the pseudo-second-order model for an initial Cr(III) and Zn(II) concentration of approximately 100 mgl(-1), at pH 5.3 and 20 degrees C were k(2,ads)=0.04 g mg(-1)Cr(III)min(-1) and 0.07 g mg(-1)Zn(II)min(-1), q(eq)=11.9 mgCr(III)g(-1) and 9.5 mgZn(II)g(-1) for algae; k(2,ads)=0.17 g mg(-1)Cr(III)min(-1) and 0.19 g mg(-1)Zn(II)min(-1), q(eq)=8.3 mgCr(III)g(-1) and 5.6 mgZn(II)g(-1) for algal waste; k(2,ads)=0.01 g mg(-1)Cr(III)min(-1) and 0.18 g mg(-1)Zn(II)min(-1), q(eq)=8.0 mgCr(III)g(-1) and 4.4 mgZn(II)g(-1) for composite material. Biosorption was modelled using a batch adsorber mass transfer kinetic model, which successfully predicts Cr(III) and Zn(II) concentration profiles. The calculated average homogeneous diffusivities, D(h), were 4.2 x 10(-8), 8.3 x 10(-8) and 1.4 x 10(-8)cm(2)s(-1) for Cr(III) and 4.8 x 10(-8), 9.7 x 10(-8) and 6.2 x 10(-8)cm(2)s(-1

  18. Brown-red pigment formation by the mycelial phase of a clinical isolate of Histoplasma capsulatum on Staib agar. A preliminary report.

    PubMed

    Staib, F; Grosse, G

    1996-04-01

    In an HIV-positive patient, the suspected diagnosis of histoplasmosis capsulatum (being the first opportunistic infection indicating AIDS) on the basis of histopathological findings in biopsy material could be proved by culture on Staib agar (syn. Guizotia abyssinica creatinine agar, bird seed agar, etc.). On Staib agar, after 4 weeks at 26 degrees C, there was a cockade-like colony growth, consisting of a white centre, followed by a brown-red pigmented zone surrounded by a border of submerged mycelial growth of tan to brownish colour. Morphologically, there was a moderate formation of tuberculate macroconidia and a heavy formation of microconidia. On neutral Sabouraud's dextrose agar, there was a colony formation without pigment (albino type) free of tuberculate macroconidia and microconidia. Proposals for further investigation of these preliminary observations are made.

  19. Evaluation of the antibacterial effects of vancomycin hydrochloride released from agar-gelatin-bioactive glass composites.

    PubMed

    Rivadeneira, Josefina; Di Virgilio, Ana Laura; Audisio, M Carina; Boccaccini, Aldo R; Gorustovich, Alejandro A

    2015-01-13

    The aim of this work was to evaluate the perfomance of agar-gelatin (AG) composites and AG-containing 45S5 bioactive glass (BG) microparticles (AGBG) in relation to their water uptake capacity, sustained release of a drug over time, and antibacterial effects. The composites were fabricated by the gel-casting method. To impart the local drug release capacity, vancomycin hydrochloride (VC) was loaded in the composites in concentrations of 0.5 and 1 mg ml(-1). VC release was assessed in distilled water at 37 °C up to 72 h and quantified spectrophotometrically. The antibacterial activity of composites was evaluated by the inhibition zone test and the plate count method. The experiments were performed in vitro up to 48 h on three staphylococcus strains: Staphylococcus aureus ATCC29213, S. aureus ATCC6538 and Staphylococcus epidermidis ATCC12228. The results showed that the addition of BG to AG composites did not affect the degree of water uptake. The release of VC was significantly affected by the presence of BG. VC release was higher from AGBGVC films than from AGVC ones over prolonged incubation times. Bacterial inhibition zones were found around the composites. The halos were larger when the cells were put in contact with AGVC composites than when they were put in contact with AGBGVC ones. Nevertheless, the viable count method demonstrated that the composites inhibited Staphylococcus cell growth with no statistical differences. In conclusion, the addition of BG did not reflect an improvement in the parameters studied. On the other hand, composites loaded with VC would have a role in prophylaxis against bacterial infection.

  20. Preparation and application of agar/alginate/collagen ternary blend functional food packaging films.

    PubMed

    Wang, Long-Feng; Rhim, Jong-Whan

    2015-09-01

    Ternary blend agar/alginate/collagen (A/A/C) hydrogel films with silver nanoparticles (AgNPs) and grapefruit seed extract (GSE) were prepared. Their performance properties, transparency, tensile strength (TS), water vapor permeability (WVP), water contact angle (CA), water swelling ratio (SR), water solubility (WS), and antimicrobial activity were determined. The A/A/C film was highly transparent, and both AgNPs and GSE incorporated blend films (A/A/C(AgNPs) and A/A/C(GSE)) exhibited UV-screening effect, especially, the A/A/C(GSE) film had high UV-screening effect without sacrificing the transmittance. In addition, the A/A/C blend films formed efficient hydrogel film with the water holding capacity of 23.6 times of their weight. Both A/A/C(AgNPs) and A/A/C(GSE) composite films exhibited strong antimicrobial activity against both Gram-positive (Listeria monocytogenes) and Gram-negative (Escherichia coli) food-borne pathogenic bacteria. The test results of fresh potatoes packaging revealed that all the A/A/C ternary blend films prevented forming of condensed water on the packaged film surface, both A/A/C(AgNPs) and A/A/C(GSE) composite films prevented greening of potatoes during storage. The results indicate that the ternary blend hydrogel films incorporated with AgNPs or GSE can be used not only as antifogging packaging films for highly respiring fresh agriculture produce, but also as an active food packaging system utilizing their strong antimicrobial activity.

  1. In vitro antifungal susceptibility testing of Scopulariopsis brevicaulis strains using agar diffusion method.

    PubMed

    Skóra, Magdalena; Macura, Anna B

    2011-01-01

    The genus Scopulariopsis is a common soil saprotroph and has been isolated from air, organic waste and also from plant, animal and human tissues. Scopulariopsis has mainly been associated in humans with superficial mycoses, but it has also been described as the cause of subcutaneous and invasive infections. The most common aetiological agent of infections in humans is Scopulariopsis brevicaulis. This species has been reported to be resistant in vitro to broad-spectrum antifungal agents available today. The aim of the study was to establish in vitro antifungal susceptibility of 35 S. brevicaulis strains against amphotericin B (AMB), flucytosine (FC), caspofungin (CAS), terbinafine (TER), ciclopirox (CIC), voriconazole (VOR), clotrimazole (CTR), miconazole (MCZ), econazole (ECO), ketoconazole (KET), itraconazole (ITR), and fluconazole (FLU). Antifungal susceptibility tests were evaluated by an agar diffusion method (Neo-Sensitabs, Rosco, Denmark). AMB, FC, CAS, ITR and FLU showed no antifungal activity against S. brevicaulis. TER, CIC, CTR, KET, VOR, ECO, and MCZ revealed inhibitory activity for S. brevicaulis, but it varied for each of the drugs. The best antifungal effect was observed for TER and CIC. All isolates had large inhibition zones for TER and CIC. CTR was also inhibitory for all tested S. brevicaulis isolates, but the diameters of inhibition zones were smaller than for TER and CIC. Nearly 89% isolates showed inhibition zones for KET and the mean diameter of the inhibition zone was comparable to CTR. The least antifungal activity exhibited VQR, ECO and MCZ. Because of the multiresistance of S. brevicaulis, infections due to this species may not respond to particular antifungal treatment and other therapeutic approaches should be considered, e.g., combined therapy and/or surgery.

  2. Effect of EDTA on Pb(II) Uptake and Translocation by Tumbleweed (Salsola Kali): Agar and Hydroponics Studies

    SciTech Connect

    de la Rosa, Guadalupe; Gardea-Torresdey, Jorge L.; Peralta-Videa, Jose R.; Aldrich, Mary

    2004-03-31

    Environmental accumulation of Pb represents a worldwide health hazard. While conventional cleanup techniques are generally expensive and soil disturbing, phytoremediation represents an inexpensive friendly option for the removal of contaminants from soil and water. In this research, tumbleweed (Salsola kali) plants exposed for 15 days to Pb(NO3)2 at 80 and 125 ppm in hydroponics and agar media, demonstrated a high capacity to uptake lead. The results showed that the plants cultivated in agar accumulated 25563, 5534 and 2185 mg Pb kg-1 DW in roots, stems and leaves, respectively. Moreover, Pb concentrations found in hydroponically grown tumbleweed plants tissues were 30744, 1511 and 1421 mg kg-1 DW in roots, stems and leaves, respectively. It was observed that EDTA enhanced Pb translocation. No Pb phytotoxic effects were observed during the experimental time period. Cellular structural features were also observed using TEM.

  3. A new chromogenic agar medium, chromID VRE, to screen for vancomycin-resistant Enterococcus faecium and Enterococcus faecalis.

    PubMed

    Ledeboer, Nathan A; Tibbetts, Robert J; Dunne, William M

    2007-12-01

    We compared the performance of a chromogenic agar medium chromID VRE (bioMérieux, Marcy-l'Etoile, France) designed to recover and identify vancomycin-resistant enterococci (VRE) from clinical specimens with bile esculin azide vancomycin (BEAV) agar. For this study, 120 stool specimens were plated on chromID VRE and BEAV and examined after 24 and 48 h. At 24 h, the sensitivity and specificity were as follows: BEAV, 90.2% and 73%, respectively; chromID VRE, 86.3% and 100.0%, respectively. Furthermore, we determined that the sensitivity and specificity of chromID VRE for Enterococcus faecium were 85.4% and 100%, respectively, and for Enterococcus faecalis, 90% and 100%, respectively. We conclude that chromID VRE provides an equivalent sensitivity for the recovery of VRE from stool specimens, with improved specificity, and the added advantage of providing differentiation between vancomycin-resistant E. faecium and E. faecalis.

  4. [Clinical symptoms and circumastances of acute poisonings with fly agaric (Amanita muscaria) and panther cap (Amanita pantherina)].

    PubMed

    Łukasik-Głebocka, Magdalena; Druzdz, Artur; Naskret, Maciej

    2011-01-01

    Mushroom poisonings in Poland are quite common, especially in summer and autumn, but fly agaric (Amanita muscaria) and panther cap (Amanita pantherina) are rather rare cause of these intoxications. Fly agaric is a cause of deliberate poisoning, whereas panther cap poisoning also happens accidentally. The main toxins of these two mushrooms are ibotenic acid (pantherine, agarine), muscimol, muscazone and muscaridine. The other bioactive substances are stizolobic and stizolobinic acids and aminodicarboxyethylthiopropanoic acids. All these compounds are responsible for diverse picture of intoxication. An analysis of patients with Amanita muscaria and Amanita pantherina poisoning hospitalized in the Poznan Departament of Toxicology revealed that symptoms occurred after 30 minutes to 2 hours with vomiting, hallucinations, restlessness, increased psychomotor drive and central nervous system depression. Other antycholinergic symptoms like tachycardia and increased blood pressure, mydriasis, dry and red skin were seen only in a few cases. Acute respiratory failure was the most dangerous symptom observed in the course of poisoning.

  5. Natural occurrence and growth reaction on canavanine-glycine-bromothymol blue agar of non-neoformans Cryptococcus spp. in Malaysia.

    PubMed

    Tay, S T; Na, S L; Tajuddin, T H

    2008-11-01

    Cryptococcus albidus and C. laurentii were the predominant non-neoformans cryptococci isolated during an environmental sampling study for C. gattii at Klang Valley, Malaysia. Cryptococcus gattii was not isolated from any of the environmental samples. Cryptococcus albidus and C. laurentii were isolated mainly from vegetative samples of Eucalyptus trees and bird droppings. Upon testing on canavanine-glycine-bromothymol blue (CGB) agar, all the C. albidus isolates remained unchanged. Interestingly, a total of 29 (76.3%) C. laurentii isolates formed blue colours on the CGB agar. Sequence analysis of ITS1-5.8rDNA-ITS2 gene sequences (468 bp) of four CGB-blue C. laurentii isolates demonstrated the closest match (99%) with that of C. laurentii CBS 7140. This study demonstrated the diverse environmental niche of C. albidus and C. laurentii in Malaysia.

  6. Preparation of agar nanospheres: comparison of response surface and artificial neural network modeling by a genetic algorithm approach.

    PubMed

    Zaki, Mohammad Reza; Varshosaz, Jaleh; Fathi, Milad

    2015-05-20

    Multivariate nature of drug loaded nanospheres manufacturing in term of multiplicity of involved factors makes it a time consuming and expensive process. In this study genetic algorithm (GA) and artificial neural network (ANN), two tools inspired by natural process, were employed to optimize and simulate the manufacturing process of agar nanospheres. The efficiency of GA was evaluated against the response surface methodology (RSM). The studied responses included particle size, poly dispersity index, zeta potential, drug loading and release efficiency. GA predicted greater extremum values for response factors compared to RSM. However, real values showed some deviations from predicted data. Appropriate agreement was found between ANN model predicted and real values for all five response factors with high correlation coefficients. GA was more successful than RSM in optimization and along with ANN were efficient tools in optimizing and modeling the fabrication process of drug loaded in agar nanospheres.

  7. Solvent-tolerance of fungi located on an interface between an agar plate and an organic solvent.

    PubMed

    Oda, Shinobu; Sugitani, Ayaka; Ohashi, Shinichi

    2014-01-01

    While 6 by 20 of type culture fungi could grow on an interface between organic solvent (log P, 4.12) and agar plate, 13 by 20 of strains could form a large colony after the removal of more toxic solvent, such as styrene (log P, 2.95) and tert-butyl acetate (log P, 1.76) because of viability of spores on the interface.

  8. Morphometric and colorimetric analyses of human tumor cell line growth and drug sensitivity in soft agar culture.

    PubMed

    Alley, M C; Pacula-Cox, C M; Hursey, M L; Rubinstein, L R; Boyd, M R

    1991-02-15

    Previous studies have demonstrated the suitability of image analysis of tetrazolium-stained colonies to assess growth and drug sensitivity of human tumor cells cultivated in soft agar culture. In the present study, the potential utility of colorimetric analysis to expedite experimental drug evaluations using human tumor cell lines was investigated. The same culture dishes were assessed by image analysis and by formazan colorimetry for purposes of comparing multiple methods of measuring growth as well as growth inhibition. Replicate cultures treated with 2-(p-iodonitrophenyl)-3-p-nitrophenyl-5-phenyltetrazolium chloride or 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide exhibited nearly identical colony count and volume indices as well as excellent correlation in colorimetric end points. Colony-forming unit volume analysis versus colorimetric assessment of the same cultures following dimethyl sulfoxide extraction of protamine sulfate-rinsed, dried soft agar cultures exhibited excellent linear correlation for both growth (Pearson r ranging from 0.95 to 1.00) and drug sensitivity (Pearson r ranging from 0.90 to 0.99, and Spearman r ranging from 0.82 to 0.97) and similar drug sensitivity profiles. Results of the current investigation indicate that end points of soft agar culture remain stable for a period of at least 2 weeks following assay termination. In addition, a colorimetric detection range of 1.3-2.2 log units permits determinations of survival levels ranging from 100 to 5% of respective control levels. Colorimetric analysis is anticipated to expedite soft agar colony formation assay evaluations (a) by reducing the need to use the more rigorous and time-consuming image analysis procedures to measure activity in preliminary drug sensitivity assays and (b) by permitting the determination of effective concentration ranges of new experimental agents for subsequent, more detailed investigations.

  9. Isolation of Shiga Toxin-Producing Escherichia coli from Ground Beef Using Multiple Combinations of Enrichment Broths and Selective Agars.

    PubMed

    Brusa, Victoria; Piñeyro, Pablo E; Galli, Lucía; Linares, Luciano H; Ortega, Emanuel E; Padola, Nora L; Leotta, Gerardo A

    2016-03-01

    Shiga toxin-producing Escherichia coli (STEC) are foodborne pathogens, and beef cattle are recognized as the principal reservoir. The aims of this study were (1) to identify the most sensitive combination of selective enrichment broths and agars for STEC isolation in artificially inoculated ground beef samples, and (2) to evaluate the most efficient combination(s) of methods for naturally contaminated ground beef samples. A total of 192 ground beef samples were artificially inoculated with STEC and non-stx bacterial strains. A combination of four enrichment broths and three agars were evaluated for sensitivity, specificity, and positive predictive value for STEC isolation from experimentally inoculated samples. Enrichments with either modified tryptic soy broth (mTSB) containing 8 mg/L novobiocin (mTSB-8) or modified Escherichia coli (mEC) broth followed by isolation in MacConkey agar were the most sensitive combinations for STEC isolation of artificially inoculated samples. Independently, both enrichments media followed by isolation in MacConkey were used to evaluate ground beef samples from 43 retail stores, yielding 65.1% and 58.1% stx-positive samples by RT-PCR, respectively. No difference was observed in the isolate proportions between these two methods (8/25 [32%] and 8/28 [28.6%]). Identical serotypes and stx genotypes were observed in STEC strains isolated from the same samples by either method. In this study, no single enrichment protocol was sufficient to detect all STEC in artificially inoculated samples and had considerable variation in detection ability with naturally contaminated samples. Moreover, none of the single or combinations of multiple isolation agars used were capable of identifying all STEC serogroups in either artificially inoculated or naturally occurring STEC-contaminated ground beef. Therefore, it may be prudent to conclude that there is no single method or combination of isolation methods capable of identifying all STEC serogroups.

  10. Performance of Chromogenic Candida agar and CHROMagar Candida in recovery and presumptive identification of monofungal and polyfungal vaginal isolates.

    PubMed

    Ozcan, Kadri; Ilkit, Macit; Ates, Aylin; Turac-Bicer, Aygul; Demirhindi, Hakan

    2010-02-01

    Chromogenic Candida agar (OCCA) is a novel medium facilitating isolation and identification of Candida albicans, C. tropicalis, and C. krusei, as well as indicating polyfungal population in clinical samples. We compare the performance of OCCA, to CHROMagar Candida (CAC) and Sabouraud chloramphenicol agar (SCA). Vaginal swab samples from 392 women were simultaneously inoculated onto three study media. A total of 161 (41.1%) were found to be positive for fungi of which 140 (87%) were monofungal, and 21 (13%) polyfungal. One-hundred and fifty-seven samples (97.5%) were positive on CAC, 156 (96.9%) on OCCA, 148 (91.9%) on SCA and 144 (89.4%) samples were positive on all three media. The yeasts were identified by conventional methods including germ tube test, microscopic morphology on cornmeal-Tween 80 agar, and the commercial API 20C AUX. The 182 isolates were C. albicans (n = 104), C. glabrata (n = 51), C. krusei (n = 7), C. tropicalis (n = 5), C. famata (n = 3), C. kefyr (n = 3), C. zeylanoides (n = 3), C. colliculosa (n = 2), and other species of Candida (n = 4). Among the 21 polyfungal populations, 20 (95.2%) were detected in OCCA, 14 (66.7%) in CAC, and 13 (61.9%) in CAC and OCCA (P <0.05). Most polyfungal populations (47.6%) yielded C. albicans + C. glabrata. The efficiency of both chromogenic media for C. albicans was >or=92.9% at 72 h. OCCA is more efficient and reliable for rapidly identifying C. albicans and polyfungal populations than CAC. However, CAC is more efficient for identifying C. krusei and C. tropicalis. A chromogenic agar with a higher isolation rate of yeasts and better detection of polyfungal populations than SCA, is suggested as a medium of first choice when available.

  11. Comparison of the BBL CHROMagar Staph aureus Agar Medium to Conventional Media for Detection of Staphylococcus aureus in Respiratory Samples

    PubMed Central

    Flayhart, Diane; Lema, Clara; Borek, Anita; Carroll, Karen C.

    2004-01-01

    Screening for Staphylococcus aureus has become routine in certain patient populations. This study is the first clinical evaluation of the BBL CHROMagar Staph aureus agar (CSA) medium (BD Diagnostics, Sparks, Md.) for detection of S. aureus in nasal surveillance cultures and in respiratory samples from cystic fibrosis (CF) patients. S. aureus colonies appear mauve on CSA. Other organisms are inhibited or produce a distinctly different colony color. S. aureus was identified from all media by slide coagulase, exogenous DNase, and mannitol fermentation assays. Susceptibility testing was performed using the agar dilution method. A total of 679 samples were evaluated. All samples were inoculated onto CSA. Nasal surveillance cultures were inoculated onto sheep blood agar (SBA) (BD Diagnostics), and samples from CF patients were inoculated onto mannitol salt agar (MSA) (BD Diagnostics). Of the 679 samples cultured, 200 organisms produced a mauve color on CSA (suspicious for S. aureus) and 180 were positive for S. aureus on SBA or MSA. Of 200 CSA-positive samples 191 were identified as S. aureus. Nine mauve colonies were slide coagulase negative and were subsequently identified as Staphylococcus lugdunensis (one), Staphylococcus epidermidis (three), Staphylococcus haemolyticus (one), and Corynebacterium species (four). CSA improved the ability to detect S. aureus by recovering 12 S. aureus isolates missed by conventional media. Of the 192 S. aureus isolates recovered, 122 were methicillin susceptible and 70 were methicillin resistant. Overall, the sensitivity and specificity of CSA in this study were 99.5 and 98%, respectively. There was no difference in the performance of the slide coagulase test or in susceptibility testing performed on S. aureus recovered from CSA compared to SBA or MSA. Our data support the use of CSA in place of standard culture media for detection of S. aureus in heavily contaminated respiratory samples. PMID:15297498

  12. Arthromyces and Blastosporella, two new genera of conidia-producing lyophylloid agarics (Agaricales, Basidiomycota) from the neotropics.

    PubMed

    Baroni, Timothy J; Franco-Molano, Ana Esperanza; Lodge, D Jean; Lindner, Daniel L; Horak, Egon; Hofstetter, Valerie

    2007-05-01

    Two new genera encompassing three new species of lyophylloid agarics that produce conidia on the basidiomata are described. Arthromyces is a genus comprised of two very different arthrospore-producing mushroom species found in the Greater Antilles and Central America. Blastosporella is a monotypic genus with spherical balls of blastospores covering the pileus surface with age and is known from Hispaniola and Colombia. A key to the species of Arthromyces is included.

  13. Epidemiology of Klebsiella oxytoca-associated diarrhea detected by Simmons citrate agar supplemented with inositol, tryptophan, and bile salts.

    PubMed

    Cheng, Vincent C C; Yam, Wing-Cheong; Tsang, Lee-Lee; Yau, Miranda C Y; Siu, Gilman K H; Wong, Sally C Y; Chan, Jasper F W; To, Kelvin K W; Tse, Herman; Hung, Ivan F N; Tai, Josepha W M; Ho, Pak-Leung; Yuen, Kwok-Yung

    2012-05-01

    We studied the clinical and epidemiological characteristics of Klebsiella oxytoca-associated diarrhea in hospitalized patients in Hong Kong. Between 1 November 2009 and 30 April 2011, all inositol-fermenting colonies found on Simmons citrate agar supplemented with inositol, tryptophan, and bile salts (SCITB agar) used for the culturing of diarrheal stool samples were screened by a spot indole test for K. oxytoca. The overall sensitivity of SCITB agar plus the spot indole test (93.3%) for the detection of K. oxytoca in stool samples was superior to that of MacConkey agar (63.3%), while the specificities were 100% and 60.4%, respectively. The former achieved a 23-fold reduction in the workload and cost of subsequent standard biochemical identifications. Cytotoxin production and the clonality of K. oxytoca were determined by a cell culture cytotoxicity neutralization assay using HEp-2 cells and pulsed-field gel electrophoresis (PFGE), respectively. Of 5,581 stool samples from 3,537 patients, K. oxytoca was cultured from 117/5,581 (2.1%) stool samples from 104/3,537 (2.9%) patients. Seventy-six of 104 (73.1%) patients with K. oxytoca had no copathogens in their diarrheal stool samples. Twenty-four (31.6%) of 76 patients carried cytotoxin-producing strains, which were significantly associated with antibiotic therapy after hospital admission (50% versus 21.2%; P = 0.01). Health care-associated diarrhea was found in 44 (42%) of 104 patients with K. oxytoca, but there was no epidemiological linkage suggestive of a nosocomial outbreak, and PFGE showed a diverse pattern. None of the patients with cytotoxin-producing K. oxytoca developed antibiotic-associated hemorrhagic colitis, suggesting that K. oxytoca can cause a mild disease manifesting as uncomplicated antibiotic-associated diarrhea with winter seasonality.

  14. Identification of Salmonella spp. with Rambach agar in conjunction with the 4-methylumbelliferyl caprylate (MUCAP) fluorescence test.

    PubMed

    Abdalla, S; Vila, J; Jimenez de Anta, M T

    1994-03-01

    The utility of Rambach agar to identify Salmonella spp. was examined relative to its usefulness in clinical microbiology. Forty-four of 54 (82%) salmonella organisms isolated from faecal cultures and 66 of 82 (84%) salmonella stock cultures produced bright red colour colonies after 24 h incubation at 37 degrees C, whereas 48 of 54 (89%) salmonellae isolated from faecal cultures, and 74 of 82 (90%) salmonella stock cultures, yielded the bright red colour when the incubation time was extended to 48 h. Apart from Salmonella typhi and Salmonella paratyphi A the sensitivity of Rambach agar to detect salmonella strains belonging to five serogroups was 83% and 92% after 24 and 48 h of incubation, respectively. In contrast, other members of the family Enterobacteriaceae tested failed to give the bright red colour, except for one strain of Pseudomonas aeruginosa and another of Acinetobacter baumannii. The non-salmonella strains either gave a different colour--blue, green or orange--or were colourless. To supplement the use of Rambach agar in the detection of Salm. typhi and Salm. paratyphi A and other late or negative acid-producing salmonella species on this medium, the 4-methylumbelliferyl caprylate fluorescence (MUCAP) test was carried out, and this showed positive results with all the salmonella strains tested. These results suggest that while Rambach agar can not pre-identify Salm. typhi and Salm. paratyphi A, the use of a simple and rapid (MUCAP) test in combination would make it very useful to identify all Salmonella spp. after 24 h incubation.

  15. Irradiation of silver and agar/silver nanoparticles with argon, oxygen glow discharge plasma, and mercury lamp.

    PubMed

    Ahmad, Mahmoud M; Abdel-Wahab, Essam A; El-Maaref, A A; Rawway, Mohammed; Shaaban, Essam R

    2014-01-01

    The irradiation effect of argon, oxygen glow discharge plasma, and mercury lamp on silver and agar/silver nanoparticle samples is studied. The irradiation time dependence of the synthesized silver and agar/silver nanoparticle absorption spectra and their antibacterial effect are studied and compared. In the agar/silver nanoparticle sample, as the irradiation time of argon glow discharge plasma or mercury lamp increases, the peak intensity and the full width at half maximum, FWHM, of the surface plasmon resonance absorption band is increased, however a decrease of the peak intensity with oxygen glow plasma has been observed. In the silver nanoparticle sample, as the irradiation time of argon, oxygen glow discharge plasma or mercury lamp increases, the peak intensity of the surface plasmon resonance absorption band is increased, however, there is no significant change in the FWHM of the surface plasmon resonance absorption band. The SEM results for both samples showed nanoparticle formation with mean size about 50 nm and 40 nm respectively. Throughout the irradiation time with the argon, oxygen glow discharge plasma or mercury lamp, the antibacterial activity of several kinds of Gram-positive and Gram-negative bacteria has been examined.

  16. Reliability of the agar based method to assess the production of degradative enzymes in clinical isolates of Candida albicans.

    PubMed

    Arantes, Paula Tamião; Sanitá, Paula Volpato; Santezi, Carolina; Barbeiro, Camila de Oliveira; Reina, Bárbara Donadon; Vergani, Carlos Eduardo; Dovigo, Lívia Nordi

    2016-03-01

    The aim of this study was to establish a reproducible protocol using the methodology of hyaline zones around the colonies on specific agar plates for phospholipase and proteinase production. This was an in vitro double-blind experiment, in which the dependent variables were the enzymatic activity measurements (Pz) for the production of phospholipase (Pz-ph) and the production of secreted aspartyl proteinases (Pz-sap). Three independent variables give rise to different measurement protocols. All measurements were carried out at two different moments by four examiners (E1, E2, E3, and E4). The minimum sample size was 30 Candida albicans clinical isolates. Specific agar plates for phospholipase and SAPs production were prepared according the literature. The intra-and inter-examiner reproducibility for each protocol was estimated using the Intraclass Correlation Coefficient (ICC) and its confidence interval (95% CI). Based on the results obtained for both phospholipase and SAPs, there appears to be no consensus on the protocol chosen for each particular examiner. Measuring the colonies in triplicate may be the main factor associated with the increase in measurement accuracy and should therefore take precedence over measuring only one colony. When only one examiner is responsible for taking measurements, a standard protocol should be put in place and the statistical calibration of this researcher should be done prior to data collection. However, if two or more researchers are involved in the assessment of agar plates, our results suggest that the protocols using software to undertake plate reading is preferred.

  17. Metronidazole susceptibility testing for Helicobacter pylori: comparison of disk, broth, and agar dilution methods and their clinical relevance.

    PubMed Central

    DeCross, A J; Marshall, B J; McCallum, R W; Hoffman, S R; Barrett, L J; Guerrant, R L

    1993-01-01

    Since the methods for metronidazole susceptibility testing of Helicobacter pylori have not been standardized or validated, we compared three methods that are used to test the metronidazole susceptibilities of 25 isolates of H. pylori. Specifically, we examined the methods of Steer's replicator agar dilution, tube broth microdilution, and modified Kirby-Bauer disk diffusion. The metronidazole disk zone sizes obtained by the disk diffusion method correlated well (r = 0.74) with the MICs obtained by the agar dilution method. Afterward, the disk diffusion method was used to characterize the metronidazole susceptibilities of 44 isolates of H. pylori. Dual therapy (bismuth and metronidazole) proved to be highly effective against metronidazole-susceptible strains (81.6% eradication rate) but fared poorly against resistant strains (16.7% eradication rate; P < 0.01). Using agar dilution testing, we validated the modified Kirby-Bauer disk diffusion method for metronidazole susceptibility testing of H. pylori and conclude that it is practical, accurate, and clinically applicable. PMID:8370723

  18. Broth and agar hop-gradient plates used to evaluate the beer-spoilage potential of Lactobacillus and Pediococcus isolates.

    PubMed

    Haakensen, M; Schubert, A; Ziola, B

    2009-03-15

    Identification of the beer-spoilage Lactobacillus and Pediococcus bacteria has largely taken two approaches; identification of spoilage-associated genes or identification of specific species of bacteria regardless of ability to grow in beer. The problem with these two approaches is that they are either overly inclusive (i.e., detect all bacteria of a given species regardless of spoilage potential) or overly selective (i.e., rely upon individual, putative spoilage-associated genes). Our goal was to design a method to assess the ability of Lactobacillus and Pediococcus to spoil beer that is independent of speciation or genetic background. In searching for a method by which to differentiate between beer-spoilage bacteria and bacteria that cannot grow in beer, we explored the ability of lactobacilli and pediococci isolates to grow in the presence of varying concentrations of hop-compounds and ethanol in broth medium versus on agar medium. The best method for differentiating between bacteria that can grow in beer and bacteria that do not pose a threat as beer-spoilage organisms was found to be a hop-gradient agar plate containing ethanol. This hop-gradient agar plate technique provides a rapid and simple solution to the dilemma of assessing the ability of Lactobacillus and Pediococcus isolates to grow in beer, and provides new insights into the different strategies used by these bacteria to survive under the stringent conditions of beer.

  19. Measurement of human tumour cell growth in soft-agar cultures using computer-assisted volume analysis.

    PubMed Central

    Alley, M. C.; Lieber, M. M.

    1985-01-01

    Growth in soft-agar bilayer cultures of human tumour cells derived from 4 in vitro continuous cell lines, from 21 xenografts carried in athymic mice, and from 197 samples of fresh human solid tumours of various histologic types was analyzed by computer-assisted image analysis. Replicate cultures for each specimen were assessed on successive days of incubation for the number and volume of growth units within multiple size categories. Our results confirm the recent finding of others that there is an upper limit of approximately 10(9) microns 3 to the cumulative growth unit volume obtainable in a 2 ml bilayer soft agar culture system. Since this upper limit to the carrying capacity of the closed culture system exists, the extent of growth within the cultures is determined in a fundamental way by the cumulative volume of growth units initially inoculated into cultures. A growth index of greater than or equal to 16-fold was only seen when initial cumulative growth unit volume was less than 10(7) microns 3 per culture dish. Computer-assisted volume analysis (CAVA) appears to be a useful quantitative method to study the growth of human tumour cells in soft agar cultures. PMID:4027164

  20. Mechanical touch responses of Arabidopsis TCH1-3 mutant roots on inclined hard-agar surface

    NASA Astrophysics Data System (ADS)

    Zha, Guodong; Wang, Bochu; Liu, Junyu; Yan, Jie; Zhu, Liqing; Yang, Xingyan

    2016-01-01

    The gravity-induced mechanical touch stimulus can affect plant root architecture. Mechanical touch responses of plant roots are an important aspect of plant root growth and development. Previous studies have reported that Arabidopsis TCH1-3 genes are involved in mechano-related events, how-ever, the physiological functions of TCH1-3 genes in Arabidopsis root mechanoresponses remain unclear. In the present study, we applied an inclined hard agar plate method to produce mechanical touch stimulus, and provided evidence that altered mechanical environment could influence root growth. Furthermore, tch1-3 Arabidopsis mutants were investigated on inclined agar surfaces to explore the functions of TCH1-3 genes on Arabidopsis root mechanoresponses. The results showed that two tch2 mutants, cml24-2 and cml24-4, exhibited significantly reduced root length, biased skewing, and decreased density of lateral root. In addition, primary root length and density of lateral root of tch3 (cml12-2) was significantly decreased on inclined agar surfaces. This study indicates that the tch2 and tch3 mutants are hypersensitive to mechanical touch stimulus, and TCH2 (CML24-2 and CML24-4) and TCH3 (CML12-2) genes may participate in the mechanical touch response of Arabidopsis roots.

  1. Development of blood-yolk-polymyxin B-trimethoprim agar for the enumeration of Bacillus cereus in various foods.

    PubMed

    Kim, Dong-Hyeon; Kim, Hyunsook; Chon, Jung-Whan; Moon, Jin-San; Song, Kwang-Young; Seo, Kun-Ho

    2013-07-15

    Blood-yolk-polymyxin B-trimethoprim agar (BYPTA) was developed by the addition of egg yolk, laked horse blood, sodium pyruvate, polymyxin B, and trimethoprim, and compared with mannitol-yolk-polymyxin B agar (MYPA) for the isolation and enumeration of Bacillus cereus (B. cereus) in pure culture and various food samples. In pure culture, there was no statistical difference (p>0.05) between the recoverability and sensitivity of MYPA and BYPTA, whereas BYPTA exhibited higher specificity (p<0.05). To evaluate BYPTA agar with food samples, B. cereus was experimentally spiked into six types of foods, triangle kimbab, sandwich, misugaru, Saengsik, red pepper powder, and soybean paste. No statistical difference was observed in recoverability (p>0.05) between MYPA and BYPTA in all tested foods, whereas BYPTA exhibited higher selectivity than MYPA, especially in foods with high background microflora, such as Saengsik, red pepper powder, and soybean paste. The newly developed selective medium BYPTA could be a useful enumeration tool to assess the level of B. cereus in foods, particularly with high background microflora.

  2. Nutrient limitation leads to penetrative growth into agar and affects aroma formation in Pichia fabianii, P. kudriavzevii and Saccharomyces cerevisiae.

    PubMed

    van Rijswijck, Irma M H; Dijksterhuis, Jan; Wolkers-Rooijackers, Judith C M; Abee, Tjakko; Smid, Eddy J

    2015-01-01

    Among fermentative yeast species, Saccharomyces cerevisiae is most frequently used as a model organism, although other yeast species may have special features that make them interesting candidates to apply in food-fermentation processes. In this study, we used three yeast species isolated from fermented masau (Ziziphus mauritiana) fruit, S. cerevisiae 131, Pichia fabianii 65 and Pichia kudriavzevii 129, and determined the impact of nitrogen and/or glucose limitation on surface growth mode and the production of volatile organic compounds (VOCs). All three species displayed significant changes in growth mode in all nutrient-limited conditions, signified by the formation of metafilaments or pseudohyphae. The timing of the transition was found to be species-specific. Transition in growth mode is suggested to be linked to the production of certain fusel alcohols, such as phenylethyl alcohol, which serve as quorum-sensing molecules. Interestingly, we did not observe concomitant increased production of phenylethyl alcohol and filamentous growth. Notably, a broader range of esters was found only for the Pichia spp. grown on nitrogen-limited agar for 21 days compared to nutrient-rich agar, and when grown on glucose- and glucose- plus nitrogen-limited agar. Our data suggest that for the Pichia spp., the formation of esters may play an important role in the switch in growth mode upon nitrogen limitation. Further biological or ecological implications of ester formation are discussed.

  3. Beyond Agar: Gel Substrates with Improved Optical Clarity and Drug Efficiency and Reduced Autofluorescence for Microbial Growth Experiments

    PubMed Central

    McElfresh, Cameron; Wong, Lily R.

    2015-01-01

    Agar, a seaweed extract, has been the standard support matrix for microbial experiments for over a century. Recent developments in high-throughput genetic screens have created a need to reevaluate the suitability of agar for use as colony support, as modern robotic printing systems now routinely spot thousands of colonies within the area of a single microtiter plate. Identifying optimal biophysical, biochemical, and biological properties of the gel support matrix in these extreme experimental conditions is instrumental to achieving the best possible reproducibility and sensitivity. Here we systematically evaluate a range of gelling agents by using the yeast Saccharomyces cerevisiae as a model microbe. We find that carrageenan and Phytagel have superior optical clarity and reduced autofluorescence, crucial for high-resolution imaging and fluorescent reporter screens. Nutrient choice and use of refined Noble agar or pure agarose reduce the effective dose of numerous selective drugs by >50%, potentially enabling large cost savings in genetic screens. Using thousands of mutant yeast strains to compare colony growth between substrates, we found no evidence of significant growth or nutrient biases between gel substrates, indicating that researchers could freely pick and choose the optimal gel for their respective application and experimental condition. PMID:26070672

  4. Choline chloride based ionic liquid analogues as tool for the fabrication of agar films with improved mechanical properties.

    PubMed

    Sousa, Ana M M; Souza, Hiléia K S; Latona, Nicholas; Liu, Cheng-Kung; Gonçalves, Maria P; Liu, LinShu

    2014-10-13

    In the present paper, we test the suitability of ChCl/urea (DES-U) and ChCl/glycerol (DES-G) eutectic mixtures, each one prepared at 1:2 molar ratio, for the production of agar films. A three-step process is proposed: pre-solubilization of polymer in DES followed by compression-molding and subsequent drying. The mechanical properties, water resistance and microstructure of the films were evaluated at different polymer concentrations (i.e. 2-6%, w/w). DES-U showed by far, the best film forming ability. Agreeing with the diffusion and SEM data, films with the best mechanical properties were found at the lowest and highest agar concentrations (tensile strengths of 24.2-42 MPa and elongations of 15.4-38.9%). The water sorption and contact angle studies suggested increased hydrophilicity for the film containing the lowest concentration of agar. The use of choline chloride based ionic liquid analogues as solvent and plasticizer might be a promising tool for the development of new non-aqueous materials based on seaweed polysaccharides.

  5. Antibiotic Resistance: New Challenge in the Management of Bacterial Eye Infections.

    PubMed

    Talukder, A K; Sultana, Z; Jahan, I; Khanam, M; Rahman, M; Rahman, M F; Rahman, M B

    2017-01-01

    Ophthalmologists are still facing difficulties in managing bacterial eye infections. The study was designed for the isolation and identification of bacteria from infected eyes and observation of the sensitivity and resistant pattern. This cross sectional study was performed among 160 patients of suspected bacterial eye infection at Dr. K. Zaman BNSB Eye Hospital, Mymensingh and Department of Microbiology and Hygiene, Bangladesh Agricultural University, Mymensingh from March, 2010 to June, 2014. After collection of the samples from suspected infected eyes, it was nourished into nutrient broth in shaking incubator for three hours and then cultured into nutrient agar media followed by Mannitol salt agar, MacConkey's agar and blood agar. Bacteria were categorized by colony characteristics and Gram staining. Antibiogram was performed by disc diffusion method on Mueller Hinton agar media. McFarland Equivalence Turbidity Standard was maintained. The efficacy of the drug was evaluated by measuring the diameter of the zone of inhibition surrounding the disc. Ten percent Staphylococcus species isolates was resistant to Gatifloxacin, Gentamicin, Tobramycin and Cloxacillin, 26.0% to Ciprofloxacin, 40.0% to Azythromycin and Moxifloxacin, 58.0% to Cefixime and 64.0% to Cephalexin. Methicillin resistant Staphylococcus aureus was 62.8%. About 24.0% Streptococcus species isolates was resistant to Gatifloxacin, 33.3% to Azythromycin, Ciprofloxacin, Gentamycin, Moxifloxacin and Tobramycin, 52.4% to Cefixime and 71.4% to Cephalexin. About 9.0% of Pseudomonas species was resistant to Gatifloxacin and Tobramycin, 14.7% to Ciprofloxacin, 26.5% to Cefixime, 29.4% to Gentamicin and Moxifloxacin, 44.1% to Azythromycin and 82.3% to Cephalexin and Cloxacillin. Rational use of antibiotics and proper attentions of concerned authorities are necessary to overcome the emergent ocular situation leaded by antibiotic resistant.

  6. Antibacterial activity of Thymus daenensis methanolic extract.

    PubMed

    Mojab, Faraz; Poursaeed, Mahshid; Mehrgan, Hadi; Pakdaman, Shima

    2008-07-01

    Medicinal plants are potential of antimicrobial compounds. The present study deals with the antibacterial activity of methanolic extract of Thymus daenensis. Aerial parts of the plant were collected from Alvand mountainside (Hamadan, Iran) in May 2005, air-dried and extracted by methanol. The dried extract was redissolved in methanol to make a 100 mg/ml solution and then filtered. Antibacterial activity of the extract was evaluated against various Gram-positive and Gram-negatives bacteria using disk diffusion technique. Blank paper disks were loaded with 40 microl of the methanol solution and then dried up. The impregnated disks were placed on Mueller-Hinton agar inoculated with bacterial suspension equal to 0.5 McFarland. The extract inhibited the growth Gram-positive bacteria, i.e., Staphylococcus aureus, Micrococcus luteus, Entrococcus faecalis, Streptococcus pyogenes, but it showed no activity against Gram-negative bacteria. The most significant effect was seen against S.aureus including MRSA, which are important nosocomial pathogens. MIC90 of the extract was determined against Gram-positive bacteria (3.12 mg/ml) and 11 MRSA strain (1.56 mg/ml).

  7. [Influence of staphylococcin T on Enterococcus sp. growth].

    PubMed

    Białucha, Agata; Kozuszko, Sylwia; Gospodarek, Eugenia; Bugalski, Roman Marian; Gierlotka, Krzysztof

    2007-01-01

    Bacteriocins are ribosomally synthesised, extracellular bacterial products. Generally, spectrum of inhibition is limited to the same or closely related species to bacteriocin producer. Staphylococcin T is produced by Staphylococcus cohnii strain. The present study concerns influence of StT to 267 Enterococcus sp. strains growth isolated between 2003 and 2006 in Department of Microbiology University Hospital of dr. A. Jurasz in Bydgoszcz. S. cohnii T antagonistic ability evaluated towards bacteries on Mueller-Hinton Agar (bio Mérieux) in aerobic conditions. After 24 and 48 hours tested enterococci suspensions were plated perpendiculary. Susceptibility to antibiotics was assessed by disc diffusion method according to the guideless of Clinical and Laboratory Standards Institute and National Reference Centre for Antimicrobial Susceptibility. Among Enterococcus sp. strains tested 7.1% were sensitive to StT. The highest percentage of sensitive enterococci isolated from wound swabs, urine, blood and pus. Enterococcus faecium strains dominated (63.2%) among enterococci sensitive to StT. Moderate inhibition degree on S. cohnii T bacteriocin action was observed in majority sensitive enterococci strains. Enterococcus sp. sensitive to StT strains were frequently multidrug resistant (68.4%). According to the study results and increasing resistance to antibiotics, StT could be an alternative agent used to treat infections caused by Enterococcus sp.

  8. Trimebutine as a potential antimicrobial agent: a preliminary in vitro approach

    PubMed Central

    KountourasJ, E; Sofianou, D; Gavalas, E; Sianou, E; Zavos, C; Meletis, G; Tsiaousi, E

    2012-01-01

    Aim: The aim of this preliminary study was to investigate the in vitro effect of "non-antibiotic" trimebutine against reference strains Staphylococcus aureus ATCC 29213, ATCC 25923, Escherichia coli ATCC 25922, ATCC 35218, Pseudomonas aeruginosa ATCC 27853 and Enterococcus faecalis ATCC 29212; microbiota that are potentially involved in the pathophysiology of post-infectious functional gastrointestinal disorders. Methods: Trimebutine activity was assessed by the broth microdilution method according to Clinical and Laboratory Standards Institute recommendations against reference strains S. aureus ATCC 29213 and ATCC 25923, E. coli ATCC 25922 and ATCC 35218, P. aeruginosa ATCC 27853 and E. faecalis ATCC 29212. Bactericidal activity of the compound was determined by spreading a 10 μL aliquot on Mueller-Hinton agar from each dilution showing non-visible growth. All tests were carried out in triplicate. Results: Trimebutine was active against all strains tested presenting with MIC ranging from 1024 to 4000 mg/L. MIC and MBC were similar for E. coli ATCC 25922 and P. aeruginosa ATCC 27853 whereas for Gram-positive isolates and E. coli ATCC 35218 the MBC was higher. Conclusions: We demonstrated the in vitro bacteriostatic/bactericidal activity of trimebutine against bacteria frequently colonizing the gastrointestinal tract and potentially involved in human gastrointestinal infections that might trigger post-infectious functional gastrointestinal disorders. PMID:23935315

  9. Addition of thymidine to culture media for accurate examination of thymidine-dependent small-colony variants of methicillin-resistant Staphylococcus aureus: a pilot study.

    PubMed

    Horiuchi, Kazuki; Matsumoto, Takehisa; Ota, Yusuke; Kasuga, Eriko; Negishi, Tatsuya; Yaguchi, Tomomi; Sugano, Mitsutoshi; Honda, Takayuki

    2015-03-01

    Small-colony variants (SCVs) are slow-growing subpopulations of various auxotrophic bacterial strains. Thymidine-dependent SCVs (TD-SCVs) are unable to synthesize thymidine; hence, these variants fail to grow in a medium without thymidine. In this study, we used 10 TD-SCVs of Staphylococcus aureus, of which four strains possessed mecA. We compared the efficacy of a newly modified medium containing thymidine for the detection of TD-SCVs of methicillin-resistant S. aureus (MRSA) to the efficacy of routinely used laboratory media. We observed that none of the 10 TD-SCVs of S. aureus grew in Mueller-Hinton agar, and four TD-SCVs of MRSA failed to grow on all MRSA screening media, except for the ChromID™ MRSA medium. Laboratory tests conducted using medium with thymidine incorporated showed that thymidine did not affect the minimum inhibitory concentrations of oxacillin and cefoxitin for clinical isolates of S. aureus, and was able to detect MRSA, including TD-SCVs. These findings showed that thymidine-incorporated media are able to detect TD-SCVs of MRSA without altering the properties of other clinically isolated MRSA strains.

  10. [Inhibition of Paenibacillus larvae employing a mixture of essential oils and thymol].

    PubMed

    Fuselli, S R; García De La Rosa, S B; Gende, L B; Eguaras, M J; Fritz, R

    2006-01-01

    In vitro antimicrobial activity of a mixture of two essential oils and thymol against Paenibacillus larvae, causal agent of American Foulbrood (AFB), was evaluated. The essential oils were extracted from cinnamon (Cinnamomum zeylanicum) and thyme (Thymus vulgaris). The third component used, thymol, is the major component of the essential oil of thyme which contains 39.9% of thymol. Minimal inhibitory concentration (MIC) in Mueller-Hinton broth by the tube dilution method and minimal bactericide concentration (MBC) on MYPGP agar were evaluated. Thyme registered MIC values of 150-250 microg/ml and MBC values of 200-300 microg/ml, while the MIC and MBC values obtained for cinnamon were of 50-100 microg/ml and 100-125 microg/ml. Thymol showed similar MIC and MBC values of 100-150 microg/ml. No significant differences between the bacterial strains were detected, but significant differences between essential oils and thymol activity were registered (P<0,01). An inhibitory synergetic effect on AFB was observed reducing MIC and MBC values due to the use of a mixture of 62.5% of thyme, 12.5% of cinnamon and 25% of thymol.

  11. The effects of different intensities, frequencies and exposure times of extremely low-frequency electromagnetic fields on the growth of Staphylococcus aureus and Escherichia coli O157:H7.

    PubMed

    Bayır, Ece; Bilgi, Eyüp; Şendemir-Ürkmez, Aylin; Hameş-Kocabaş, E Esin

    2015-03-01

    The impact of different types of extremely low-frequency electromagnetic fields (ELF-EMF) on the growth of Staphylococcus aureus and Escherichia coli O157:H7 was investigated. The cultures of bacteria in broth media were exposed to sinusoidal homogenous ELF-EMF with 2 and 4 mT magnetic intensities. Each intensity for each bacteria was combined with three different frequencies (20, 40 and 50 Hz), and four different exposure times (1, 2, 4 and 6 h). A cell suspension of each experiment was diluted for the appropriate range and inoculated to Mueller-Hinton Agar (MHA) plates after exposure to ELF-EMF. The number of colony forming units (CFU) of both strains was obtained after incubation at 37 °C for 24 h. Data were statistically evaluated by one-way analysis of variance (ANOVA), statistical significance was described at p < 0.05 and data were compared with their non-exposed controls. Magnetic intensity, frequency and exposure time of ELF-EMFs changed the characteristic responses for both microorganisms. Samples exposed to ELF-EMF showed a statistically significant decrease compared to their controls in colony forming capability, especially at long exposure times. An exposure to 4 mT-20 Hz ELF-EMF of 6 h produced maximum inhibition of CFU compared to their controls for both microorganisms (95.2% for S. aureus and 85% for E. coli).

  12. Antimicrobial Activity of Calcium Hydroxide and Betamethasone on Enterococcus faecalis; An in vitro Assessment

    PubMed Central

    Tabrizizadeh, Mahdi; Rasti, Mojtaba; Ayatollahi, Fatemeh; Mossadegh, Mohammad Hossein; Zandi, Hengameh; Dehghan, Farzad; Mousavi, Zohreh

    2015-01-01

    Introduction: Calcium hydroxide (CH) is one of the most common intracanal medications. Corticosteroids (CS) are used in endodontics because of their anti-inflammatory activity. This study aimed to evaluate the antimicrobial effect of CH+betamethasone and CH+saline against Enterococcus faecalis (E. faecalis) using agar diffusion test and measuring the microbial zone of inhibition (ZOI). Methods and Materials: Four plates containing Mueller-Hinton broth and E. faecalis culture media, were prepared. In each plate, 5 holes (5×3 mm) were created and a creamy mixture of CH+betamethasone was inserted into the holes (10 holes for each material). Two holes with ampicillin disks and two empty holes were used as negative and positive controls, respectively. Plates were incubated for 24 h and then the diameter of microbial ZOI was measured. The pH of each mixture was measured by pH meter. Data were analyzed using the Mann-Whitney U test. Results: The mean diameter of ZOI for CH+betamethasone and CH+saline was 3.4 and 3 mm, respectively. The difference was not significant (P=0.143). The pH was 12.5 for CH+saline and 12.3 CH+betamethasone, respectively. Conclusion: The mixture of CH+betamethasone had good antimicrobial effects against E. faecalis. Further studies are needed to confirm the value of this mixture in clinical settings. PMID:26213541

  13. Interpretation of the Disk Diffusion Susceptibility Test for Amikacin: Report of a Collaborative Study

    PubMed Central

    Washington, John A.; Yu, Pauline K. W.; Gavan, Thomas L.; Schoenknecht, Fritz D.; Thornsberry, Clyde

    1979-01-01

    Because excessively high rates of false resistance have been encountered with the 10-μg amikacin disk in diffusion susceptibility tests, a study was performed to examine existing zone diameter interpretative criteria and to compare the accuracy of 10- and 30-μg amikacin disks by the error rate-bounded classification scheme. Although current zone diameter interpretative criteria eliminate false susceptibles, there is an unacceptably high rate of false resistants. This problem can be resolved in most instances by revising the zone diameter interpretative criteria for the 10-μg disk (resistant, ≤9 mm; indeterminate, 10 to 11 mm; susceptible, ≥12 mm) or, preferably, by replacing the 10-μg disk with a 30-μg disk and adopting new interpretative criteria (resistant, ≤14 mm; indeterminate, 15 to 16 mm; susceptible, ≥17 mm). Because of significant differences in performance among media, it is necessary to include Pseudomonas aeruginosa ATCC 27853 among controls routinely tested and to exclude from use lots of Mueller-Hinton agar yielding results outside the 75% tolerance (90% confidence) limits for amikacin. PMID:464567

  14. Antimicrobial susceptibility of Streptococcus suis isolated from swine in France and from humans in different countries between 1996 and 2000.

    PubMed

    Marie, J; Morvan, H; Berthelot-Hérault, F; Sanders, P; Kempf, I; Gautier-Bouchardon, A V; Jouy, E; Kobisch, M

    2002-08-01

    The susceptibility of 135 Streptococcus suis strains isolated from pigs (n = 110) and from humans (n = 25) to 13 antimicrobial agents was studied by microdilution and disc diffusion methods using Mueller-Hinton Agar II (MH) supplemented with either defibrinated sheep blood (MHSB) or horse serum (MHHS). Results were similar for both methods used except for penicillin G whose zone diameters were reduced with MHSB compared with MHHS. When MH was supplemented with sheep blood, 39% of S. suis strains classified as penicillin susceptible by MHHS microdilution showed intermediate susceptibility. Nearly all strains were susceptible to penicillin G (except by disc diffusion in MHSB), amoxicillin, ceftiofur, florfenicol, gentamicin and bacitracin. The least active antimicrobial agents were doxycycline and macrolides/lincosamides. High-level resistance (MIC > 500 mg/L or zone diameters < 10 mm) to streptomycin and kanamycin was detected in only a few strains. The virulence of strains did not seem to be related to antimicrobial resistance because no statistical difference was reported between the proportion of resistant strains of S. suis isolated from pigs with meningitis, septicaemia and arthritis, and those from tonsils and nasal cavities. However, significant differences were found in the proportions of macrolide- or doxycycline-resistant strains between S. suis serotype 2 and other serotypes. The results of antibiotic susceptibility testing presented in this study indicate that beta-lactams can be used in empirical treatment of human and pig S. suis infections in France.

  15. D test: a simple test with big implication for Staphylococcus aureus macrolide-lincosamide-streptograminB resistance pattern.

    PubMed

    Shrestha, B; Rana, S S

    2014-09-01

    D test is a simple disc diffusion test giving high throughput results. It is used to study the macrolide lincosamide streptogramin resistance (MLSB), both constitutive and inducible as well as macrolide streptogramin resistance (MSB) in Staphylococcus aureus. In this test, erythromycin (macrolide) and clindamycin (lincosamide derivative) discs are placed adjacent to each other over the Mueller Hinton agar medium inoculated with the test organism. The growth of the organism up to the edges of the disc, flattening of the clindamycin zone (D test positive) near the erythromycin disc (resistant) and susceptible to both antibiotics implicate that the organism is having constitutive MLSB (CMLSB), inducible MLSB (IMLSB) and no resistance respectively. Further, the organism susceptible to clindamycin without any flattening of the zone (D test negative) near clindamycin disc (resistant) implicates that the organism is having macrolide streptogramin resistance (MSB). The test is performed in the same MHA plate in which the antibiotic sensitivity test is being done, taking into consideration that the discs are placed adjacent to each other maintaining the distance. Since clindamycin and streptogramin are among the few drugs of choice in the treatment of methicillin resistant S. aureus (MRSA) infections, knowing the resistance to these antibiotics is imperative.

  16. Effects of bovine milk lactoperoxidase system on some bacteria.

    PubMed

    Cankaya, M; Sişecioğlu, M; Bariş, O; Güllüce, M; Ozdemir, H

    2010-01-01

    Bovine lactoperoxidase (LPO) was purified from skimmed milk using amberlite CG-50-H+ resin, CM sephadex C-50 ion-exchange chromatography, and sephadex G-100 gel filtration chromatography. Lactoperoxidase was purified 20.45-fold with a yield of 28.8%. Purity of enzyme checked by sodium dodecyl sulphate-polyacrylamide gel electrophoresis method and a single band was observed. Km was 0.25 mM at 20 degrees C, Vmax value was 7.95 micromol/ml min at 20 degrees C (pH 6.0). Antibacterial study was done by disk diffusion method of Kir-by-Bauer using Mueller-Hinton agar medium with slight modification. Bovine LPO showed high antibacterial activity in 100 mM thiocyanate-100 mM H2O2 medium for some bacteria (Brevibacillus centrosaurus, B. choshinensis, B. lyticum, Cedecea davisae, Chryseobacterium indoltheticum, Clavibacter michiganense pv. insidiosum, Kocuria erythromyxa, K. kristinae, K. rosea, K. varians, Paenibacillus validus, Pseudomonas syringae pv. populans, Ralstonia pickettii, Rhodococcus wratislaviensis, Serratia fonticola, Streptomyces violaceusniger, Vibrio cholerae-nonO1) respectively, and compared with well known antibacterial substances (levofloxacin, netilmicin). LPO system has inhibition effects on all type bacteria and concentration is really important such as LPO-100 mM thiocyanate-100 mM H2O2 system was proposed as an effective agent against many factors causing several diseases.

  17. Synthesis of silver nanoparticles in montmorillonite and their antibacterial behavior

    PubMed Central

    Shameli, Kamyar; Ahmad, Mansor Bin; Zargar, Mohsen; Yunus, Wan Md Zin Wan; Rustaiyan, Abdolhossein; Ibrahim, Nor Azowa

    2011-01-01

    Silver nanoparticles (Ag NPs) were synthesized by the chemical reducing method in the external and interlamellar space of montmorillonite (MMT) as a solid support at room temperature. AgNO3 and NaBH4 were used as a silver precursor and reducing agent, respectively. The most favorable experimental conditions for synthesizing Ag NPs in the MMT are described in terms of the initial concentration of AgNO3. The interlamellar space limits changed little (d-spacing = 1.24–1.47 nm); therefore, Ag NPs formed on the MMT suspension with d-average = 4.19–8.53 nm diameter. The Ag/MMT nanocomposites (NCs), formed from AgNO3/MMT suspension, were characterizations with different instruments, for example UV-visible, PXRD, TEM, SEM, EDXRF, FT-IR, and ICP-OES analyzer. The antibacterial activity of different sizes of Ag NPs in MMT were investigated against Gram-positive, ie, Staphylococcus aureus and methicillin-resistant S. aureus (MRSA) and Gram-negative bacteria, ie, Escherichia coli, Escherichia coli O157:H7, and Klebsiella pneumoniae, by the disk diffusion method using Mueller-Hinton agar (MHA). The smaller Ag NPs were found to have significantly higher antibacterial activity. These results showed that Ag NPs can be used as effective growth inhibitors in different biological systems, making them applicable to medical applications. PMID:21674015

  18. Antimicrobial activity of tetraacetylethylenediamine-sodium perborate versus sodium hypochlorite against Enterococcus faecalis

    PubMed Central

    Shakouie, Sahar; Salem Milani, Amin; Eskandarnejad, Mahsa; Rahimi, Saeed; Froughreyhani, Mohammad; Galedar, Saeede; Ranjbar, Ehsan

    2016-01-01

    Background. This study evaluated the antimicrobial activity of Tetraacetylethylenediamine-sodium perborate (TAED-SP) in comparison to 2.5% and 5% sodium hypochlorite (NaOCl) against Enterococcus faecalis. Methods. A standard suspension of E. faecalis was inoculated on 60 plates containing Mueller-Hinton agar culture medium. Four sterile disks of Beckman filtration paper were placed on each plate. TAED-SP, 5% and 2.5% NaOCl were placed on three disks. Sterile physiologic saline was placed on the fourth disk as negative control. After 24-hour incubation, the diameter of the inhibition zone around the disks was measured using a transparent ruler. One-way Analysis of Variance (ANOVA) was used to compare the mean zone of microbial growth in the groups. P-values less than 0.05 were considered statistically significant. Results. There was a significant difference in the diameter of the inhibition zones between groups (P < 0.05). The Tukey post hoc test showed a higher diameter of the inhibitory zone with TAED-SP than that of 2.5% NaOCl. However, there were no significant differences between the inhibitory zones of TAED-SP and 5% NaOCl. Conclusion. TAED-SP and 5% NaOCl have similar antibacterial activity against E. faecalis; however, TAED-SP has a greater antibacterial effect compared to 2.5% NaOCl. PMID:27092214

  19. Enhanced catalytic efficiency of endo-β-agarase I by fusion of carbohydrate-binding modules for agar prehydrolysis.

    PubMed

    Alkotaini, Bassam; Han, Nam Soo; Kim, Beom Soo

    2016-11-01

    Recently, Microbulbifer thermotolerans JAMB-A94 endo-β-agarase I was expressed as catalytic domain (GH16) without a carbohydrate-binding module (CBM). In this study, we successfully constructed different fusions of GH16 with its original CBM6 and CBM13 derived from Catenovulum agarivorans. The optimum temperature and pH for fusions GH16-CBM6, GH16-CBM13, GH16-CBM6-CBM13 and GH16-CBM13-CBM6 were similar to GH16, at 55°C and pH 7. All the constructed fusions significantly enhanced the GH16 affinity (Km) and the catalytic efficiency (Kcat/Km) toward agar. Among them, GH16-CBM6-CBM13 exhibited the highest agarolytic activity, for which Km decreased from 3.67 to 2.11mg/mL and Kcat/Km increased from 98.6 (mg/mL)(-1)sec(-1) to 400.6 (mg/mL)(-1)sec(-1). Moreover, all fusions selectively increased GH16 binding ability to agar, in which the highest binding ability of 95% was obtained with fusion GH16-CBM6-CBM13. Melted agar was prehydrolyzed with GH16-CBM6-CBM13, resulting in a degree of liquefaction of 45.3% and reducing sugar yield of 14.2%. Further addition of Saccharophagus degradans agarolytic enzymes resulted in mono-sugar yields of 35.4% for galactose and 31.5% for 3,6-anhydro-l-galactose. There was no pH neutralization step required and no 5-hydroxymethylfurfural detected, suggesting the potential of a new enzymatic prehydrolysis process for efficient production of bio-products such as biofuels.

  20. Use of urease-bromothymol blue-agar method for large-scale testing of urine on grain and seeds.

    PubMed

    Valdes, P A; Ziobro, G C; Ferrera, R S

    1996-01-01

    The current AOAC method (963.28) for large-scale (50 g) testing of urine on grain is based on the reaction of sodium in urine with magnesium uranyl acetate. Detection of sodium suggests that urine is present and that a test for urea is appropriate. Urea is detected with urease-bromothymol blue-paper and is confirmed through its reaction with xanthydrol to form dixanthylurea crystals, which are detected microscopically. The initial nonspecific test for sodium can be influenced by the presence of salt or other sodium compounds. Furthermore, the magnesium uranyl acetate spray used in Method 963.28 potentially exposes the analyst to the aerosol of a volatile, toxic uranium compound. Excess reagents and analyzed test portions must be disposed of as radioactive waste. In addition, Method 963.28 requires several steps to determine the presence of urea. The alternative AOAC method (972.41) tests for the presence of urea from urine on individual seeds. Urea is enzymatically decomposed to ammonia and carbon dioxide by urease. Liberated ammonia shifts the pH, changing the color of the indicator in the agar from yellow to blue. This study adapts Method 972.41 to larger test samples. Up to 25 g grains and seeds are sprayed with urease test agar instead of being individually immersed in the urease test agar. The modified method was used to analyze urea on seeds and grains of 24 plants from 4 families. The method has a limit of detection of one seed contaminated with 1 microgram urea.

  1. Antimicrobial Activity of Endodontic Medicaments and Vehicles using Agar Well Diffusion Method on Facultative and Obligate Anaerobes

    PubMed Central

    Bhat, Kishore G; Sogi, Suma

    2016-01-01

    Aims The aim of this study was to determine the relative antimicrobial effectiveness of these endodontic medicaments and various vehicles using an agar well diffusion assay. Materials and methods Double Antibiotic Paste(DAP), modified DAP, 2% Chlorhexidine gluconate and their combination with four vehicles namely Polyethylene glycol 400 (PEG), Propylene glycol (PG), combinations of PG with PEG and lastly Glycerine were tested using agar well diffusion assay. The minimum bactericidal concentration was noted against four standard strains of organisms ie Streptococcus mutans ATCC( American Type Culture Collection) 25175, Staphylococcus aureus ATCC 12598, Enterococcus faecalis ATCC 35550 and Eschericia coli ATCC 25922. Successful endodontic therapy depends upon thorough disinfection of root canals. In some refractory cases, routine endodontic therapy is not sufficient, so intracanal medicaments are used for proper disinfection of canals. Issues of resistance, limited spectrum of activity and lack of antifungal properties, the hunt for the ideal intracanal medicament continues. In this regard, the vehicles used to form the pastes play a supportive role by forming the appropriate consistency for placement and may dramatically influence their chemical characteristics like their solubility and diffusion. Thus, inorder to use safer and equally effective intracanal medicaments, Chlorhexidine gluconate is being unveiled in this study. Results The difference between the four vehicles when combined with the same endodontic medicament studied above is nonsignificant (NS) except against Porphyromonas gingivalis. Propylene glycol is significantly effective than Glycerine when used with DAP ie C+M medicament combination. (p = 0.029) Conclusion 2% chlorhexidine gluconate and modified DAP can definitely replace DAP and triple antibiotic paste as end-odontic medicaments with chlorhexidine having an added advantage of bactericidal action, substantivity, biocompatibility, low toxicity

  2. Optimization of modified Middlebrook 7H11 agar for isolation of Mycobacterium bovis from raw milk cheese.

    PubMed

    Forgrave, R; Donaghy, J A; Fisher, A; Rowe, M T

    2014-10-01

    Reports have highlighted the absence of contemporary peer reviewed publications pertaining to Mycobacterium bovis culture from raw milk and cheese. By replicating traditional methods, cheese-making methodology and equipment were devised to produce Cheddar (n = 6) and Caerphilly (n = 3) artificially contaminated with M. bovis (three genotypes) under stringent laboratory-containment guidelines for handling hazardous microbiological material. Middlebrook 7H11, modified for M. bovis isolation, was assessed for capacity to enumerate M. bovis despite changing cheese microflora and prolonged M. bovis exposure to the cheese matrix using maturing cheese test portions (n = 63; up to 16 weeks). Malachite green (MG) containing media isolated M. bovis at significantly (P < 0·05) lower levels than unmodified Middlebrook 7H11 agar despite MG being a common adjunct of Middlebrook 7H11 agar modified for M. bovis growth. Subsequently, a selective MG-free Middlebrook 7H11 agar modified using haemolysed red cells and calf serum was demonstrated as the best performing (P < 0·05) medium for recovery of M. bovis from typical UK cheese types, Cheddar and Caerphilly. Significance and impact of the study: Following increased M. bovis infection of UK cattle, the risk posed to consumers from consumption of unpasteurized milk and dairy products has changed. Furthermore, published methods for the culture and molecular detection of M. bovis in raw milk products are limited. Cheese-making protocols and M. bovis culture media reported here provide tools for further investigation of M. bovis survival during all stages of cheese manufacture and could inform future assessment of the risk to consumers from M. bovis contamination of unpasteurized dairy products.

  3. High internal phase agar hydrogel dispersions in cocoa butter and chocolate as a route towards reducing fat content.

    PubMed

    Skelhon, Thomas S; Olsson, Patrik K A; Morgan, Adam R; Bon, Stefan A F

    2013-09-01

    Reducing the fat content of chocolate formulations is a major challenge for the confectionery industry. We report the suspension of aqueous microgel agar particles of up to 80% v/v within sunflower oil, cocoa butter, and ultimately chocolate. The optimised emulsification process involves a shear-cooling step. We demonstrate the versatility of our method when applied to white, milk, and dark chocolate formulations, whilst preserving the desired polymorph V of the cocoa butter matrix. In addition, we show that this technology can be used as a strategy to disperse alcoholic beverages into chocolate confectionery.

  4. Multicenter clinical evaluation of VRESelect agar for identification of vancomycin-resistant Enterococcus faecalis and Enterococcus faecium.

    PubMed

    Anderson, Neil W; Buchan, Blake W; Young, Carol L; Newton, Duane W; Brenke, Connie; Lapsley, Linda; Granato, Paul A; Ledeboer, Nathan A

    2013-08-01

    A chromogenic medium for identification of vancomycin-resistant Enterococcus faecalis and Enterococcus faecium, VRESelect, was compared to bile esculin azide agar with 6 μg/ml vancomycin (BEAV) for the isolation of vancomycin-resistant enterococci (VRE) from stool specimens. At 24 to 28 h, VRESelect demonstrated 98.7% (confidence interval [CI], 96.1 to 99.7%) sensitivity and 99.0% (CI, 98.0 to 99.6%) specificity versus 85.1% (CI, 79.8 to 89.5%) and 90.1% (CI, 79.8 to 89.5%) sensitivity and specificity, respectively, for BEAV.

  5. Oxacillin susceptibility testing of Staphylococcus saprophyticus using disk diffusion, agar dilution, broth microdilution, and the Vitek GPS-105 card.

    PubMed

    Ramotar, K; Woods, W; Toye, B

    2001-08-01

    Eighty-three mecA negative isolates of S. saprophyticus had oxacillin zone diameters agar dilution, broth microdilution, or the Vitek GPS-105 card. Greater than 90% of these isolates would be considered resistant using NCCLS M7-A5, M100-S10 criteria. These results suggest that the current NCCLS MIC and zone diameter breakpoints for oxacillin resistance in coagulase-negative Staphylococci are not appropriate for S. saprophyticus as they do not correlate with the presence of the mecA gene.

  6. Highly efficient synthesis of exopolysaccharides by Lactobacillus curvatus DPPMA10 during growth in hydrolyzed wheat flour agar.

    PubMed

    Minervini, F; De Angelis, M; Surico, R F; Di Cagno, R; Gänzle, M; Gobbetti, M

    2010-06-30

    The aim of this study was to optimize the production of exopolysaccharides (EPS) by sourdough Lactobacillus curvatus DPPMA10 for industrial application. The effects of pH, temperature, planktonic or attached cells and of some food matrices as substrates were studied. Wheat flour hydrolysate (WFH), reconstituted skimmed milk (RSM) and whey milk were supplemented with fresh yeast extract, mineral salts, and/or molasses. Non-controlled pH, starting from 5.6 to 3.5, was the optimal condition for L. curvatus DPPMA10. Temperature of 30 degrees C was also found to be optimal. Solid surfaces (agar culture media) stimulated attached bacteria to synthesize EPS (> or = of two-fold, P<0.05) with respect to planktonic cells (broth media). The highest production of EPS (ca. 46-50 g/kg of wet medium) was found during growth as attached cells in WFH agar supplemented with glucose, sucrose or molasses, mineral salts and fresh yeast extract at 30 degrees C for 48 h. As shown by high-performance liquid chromatography analysis, glucose was the only hydrolysis end-product for EPS synthesized during 48 h of incubation. The EPS synthesized by L. curvatus DPPMA10 improved the quality of bread and was utilized as carbon course by intestinal strains of lactobacilli and bifidobacteria. The synthesis of EPS by L. curvatus DPPMA10 under the conditions of this study may open new perspectives for their industrial applications.

  7. Algivirga pacifica gen. nov., sp. nov., a novel agar-degrading marine bacterium of the family Flammeovirgaceae isolated from Micronesia.

    PubMed

    Kim, Jennifer Jooyoun; Kim, Ji Hyung; Kwon, Young-Kyung; Kwon, Kae Kyoung; Yang, Sung-Hyun; Jang, Jiyi; Heo, Soo-Jin; Park, Heung-Sik; Jung, Won-Kyo; Lee, Youngdeuk; Kang, Do-Hyung; Oh, Chulhong

    2013-12-01

    An aerobic, Gram-negative, coccoid to short rod-shaped and non-flagellated marine bacterial strain S354(T) was isolated from seawater of Micronesia. The strain was capable to degrade agar-forming slight depression into agar plate. Growth occurred at a temperature range of 12-44 °C, a pH range of 5-9, and a salinity range of 1-7 % (w/v) NaCl. Phylogenetic analyses based on 16S rRNA gene sequences suggested that S354(T) belongs to the family Flammeovirgaceae. The novel strain was most closely related to Limibacter armeniacum YM 11-185(T) with similarity of 92.5 %. The DNA G+C content was 43.8 mol%. The major fatty acids (>10 %) were iso-C15:0 and C16:1 ω5c. The predominant isoprenoid quinone was determined to be MK-7. Polar lipid profile of S354(T) consisted of phosphatidylethanolamine, unknown polar lipid, and unknown glycolipids. Based on the phenotypic, phylogenetic, biochemical, and physiological tests conducted in this study, S354(T) is proposed to represent a type strain of a novel genus and species. The 16S rRNA gene sequence of S354(T) is registered in GenBank under the accession number JQ639084. The type of strain Algivirga pacifica gen. nov., sp. nov. is S354(T) (=KCCM 90107(T)=JCM 18326(T)).

  8. Visualization of the Charcoal Agar Resazurin Assay for Semi-quantitative, Medium-throughput Enumeration of Mycobacteria

    PubMed Central

    Gold, Ben; Lopez Quezada, Landys; Glasheen, Jou; Ballinger, Elaine; Somersan-Karakaya, Selin; Warrier, Thulasi; Nathan, Carl

    2016-01-01

    There is an urgent need to discover and progress anti-infectives that shorten the duration of tuberculosis (TB) treatment. Mycobacterium tuberculosis, the etiological agent of TB, is refractory to rapid and lasting chemotherapy due to the presence of bacilli exhibiting phenotypic drug resistance. The charcoal agar resazurin assay (CARA) was developed as a tool to characterize active molecules discovered by high-throughput screening campaigns against replicating and non-replicating M. tuberculosis. Inclusion of activated charcoal in bacteriologic agar medium helps mitigate the impact of compound carry-over, and eliminates the requirement to pre-dilute cells prior to spotting on CARA microplates. After a 7-10 day incubation period at 37 °C, the reduction of resazurin by mycobacterial microcolonies growing on the surface of CARA microplate wells permits semi-quantitative assessment of bacterial numbers via fluorometry. The CARA detects approximately a 2-3 log10 difference in bacterial numbers and predicts a minimal bactericidal concentration leading to ≥99% bacterial kill (MBC≥99). The CARA helps determine whether a molecule is active on bacilli that are replicating, non-replicating, or both. Pilot experiments using the CARA facilitate the identification of which concentration of test agent and time of compound exposure require further evaluation by colony forming unit (CFU) assays. In addition, the CARA can predict if replicating actives are bactericidal or bacteriostatic. PMID:28060290

  9. In vitro fermentation and prebiotic potential of novel low molecular weight polysaccharides derived from agar and alginate seaweeds.

    PubMed

    Ramnani, Priya; Chitarrari, Roberto; Tuohy, Kieran; Grant, John; Hotchkiss, Sarah; Philp, Kevin; Campbell, Ross; Gill, Chris; Rowland, Ian

    2012-02-01

    Fermentation properties and prebiotic potential of novel low molecular weight polysaccharides (LMWPs) derived from agar and alginate bearing seaweeds was investigated. Ten LMWPs were supplemented to pH, temperature controlled anaerobic batch cultures inoculated with human feces from three donors, in triplicate. Microbiota changes were monitored using Fluorescent in-situ hybridization and short chain fatty acids, the fermentation end products were analysed using gas chromatography. Of the ten LMWPs tested, Gelidium seaweed CC2253 of molecular weight 64.64 KDa showed a significant increase in bifidobacterial populations from log(10) 8.06 at 0 h to log(10) 8.55 at 24 h (p = 0.018). For total bacterial populations, alginate powder CC2238 produced a significant increase from log(10) 9.01 at 0 h to log(10) 9.58 at 24 h (p = 0.032). No changes were observed in the other bacterial groups tested viz. Bacteroides, Lactobacilli/Enterococci, Eubacterium rectale/Clostridium coccoides and Clostridium histolyticum. The polysaccharides also showed significant increases in total SCFA production, particularly acetic and propionic acids, indicating that they were readily fermented. In conclusion, some LMWPs derived from agar and alginate bearing seaweeds were fermented by gut bacteria and exhibited potential to be used a novel source of prebiotics.

  10. Acrylamide synthesis using agar entrapped cells of Rhodococcus rhodochrous PA-34 in a partitioned fed batch reactor.

    PubMed

    Raj, Jog; Sharma, Nitya Nand; Prasad, Shreenath; Bhalla, Tek Chand

    2008-01-01

    The nitrile hydratase (Nhase) induced cells of Rhodococcus rhodochrous PA-34 catalyzed the conversion of acrylonitrile to acrylamide. The cells of R. rhodochrous PA-34 immobilized in 2% (w/v) agar (1.76 mg dcw/ml agar matrix) exhibited maximum Nhase activity (8.25 U/mg dcw) for conversion of acrylonitrile to acrylamide at 10 degrees C in the reaction mixture containing 0.1 M potassium phosphate buffer (pH 7.5), 8% (w/v) acrylonitrile and immobilized cells equivalent to 1.12 mg dcw (dry cell weight) per ml. In a partitioned fed batch reaction at 10 degrees C, using 1.12 g dcw immobilized cells in a final volume of 1 l, a total of 372 g of acrylonitrile was completely hydrated to acrylamide (498 g) in 24 h. From the above reaction mixture 87% acrylamide (432 g) was recovered through crystallization at 4 degrees C. By recycling the immobilized biocatalyst (six times), a total of 2,115 g acrylamide was produced.

  11. Internal structures of agar-gelatin co-hydrogels by light scattering, small-angle neutron scattering and rheology.

    PubMed

    Santinath Singh, S; Aswal, V K; Bohidar, H B

    2011-06-01

    Internal structures of agar-gelatin co-hydrogels were investigated as a function of their volumetric mixing ratio, [Formula: see text] , 1.0 and 2.0 using dynamic light scattering (DLS), small-angle neutron scattering (SANS) and rheology. The degree of non-ergodicity ( X = 0.2 ± 0.02) , which was extracted as a heterodyne contribution from the measured dynamic structure factor data remained less than that of homogeneous solutions where ergodicity is expected (X = 10. The static structure factor, I(q) , results obtained from SANS were interpreted in the Guinier regime (low-q , which implied the existence of ≈ 250 nm long rod-like structures (double-helix bundles), and the power law (intermediate-q regions) yielded I (q) ~ q(−α) with α = 2.3 , 1.8 and 1.6 for r = 0.5 , 1.0 and 2.0. This is indicative of the presence of Gaussian chains at low r , while at r = 2 there was a propensity of rod-shaped structures. The gel strength and transition temperatures measured from frequency sweep and temperature ramp studies were suggestive of the presence of a stronger association between the two biopolymer networks at higher r . The results indicate that the internal structures of agar-gelatin co-hydrogels were highly dependent on the volumetric mixing ratio.

  12. Josamycin: interpretation of inhibition zones with the Bauer-Kirby agar disk diffusion test as compared with erythromycin.

    PubMed

    Karthein, J; Spohr, M; Traub, W H

    1986-01-01

    A total of 432 clinical isolates of Staphylococcus aureus (128), coagulase-negative staphylococci (123), group A and B beta-hemolytic streptococci (61), group D streptococci (30), Streptococcus penumoniae (29), Haemophilus influenzae (19), Haemophilus parainfluenzae (12), and Legionella pneumophila (30) were examined with the agar dilution and Bauer-Kirby agar disk diffusion tests for susceptibility to josamycin as compared with erythromycin. On a weight-for-weight basis, erythromycin was more active than josamycin against all bacterial species, including L. pneumophila. Josamycin inhibited 18 of 23 S. aureus and 11 of 16 coagulase-negative staphylococcal strains resistant to erythromycin. Utilizing minimal inhibitory concentrations (MIC) breakpoints of less than or equal to 2 micrograms/ml (sensitive), 4 microgram/ml (intermediate) and of greater than or equal to 8 micrograms/ml (resistant), and inhibition zone criteria of greater than or equal to 18 mm diameter (sensitive), 14-17 mm (intermediate), and less than or equal to 13 mm (resistant), and excluding L. pneumophila, there was good correlation between erythromycin MIC and corresponding disk diffusion data for staphylococci and streptococci, but not for Haemophilus species. In comparison, josamycin yielded a significant number of minor discrepant data for group D streptococci and Haemophilus species. It is suggested that erythromycin and josamycin should not be tested against Haemophilus species, and that josamycin should be excluded from test batteries against enterococci. Erythromycin-resistant staphylococci require separate testing with josamycin.

  13. Agar-Silica-Gel Heating Phantom May Be Suitable for Long-Term Quality Assurance of MRgHIFU

    NASA Astrophysics Data System (ADS)

    Partanen, Ari

    2009-04-01

    In MRgHIFU, the purpose of frequent quality assurance is to detect changes in system performance to prevent adverse effects during treatments. Due to high ultrasound intensities in MRgHIFU, it is essential to assure that the procedure is safe and efficacious and that image-based guidance of the treatment is reliable. We aimed to develop a guideline for MRgHIFU QA by acquiring MR temperature maps during ultrasonic heating of an agar-silica-gel phantom over a four month-period using three separate MRgHIFU uterine leiomyoma treatment systems. From this data, the stability of the maximum temperature elevation, the targeting accuracy, and the dimensions of the heated volume were analyzed. Additionally, we studied the sensitivity of these parameters to reveal hypothetical decrease in HIFU performance. After calibration, the mean targeting offsets of the heated volume were observed to be less than 2 mm in the three orthogonal directions. The measured maximum temperature elevation and the length and the width of the heated volume remained consistent throughout the four-month period. Furthermore, it was found that the parameters under investigation were sensitive to reveal the decreased HIFU performance. We conclude that an agar-silica -based phantom is suitable for targeting accuracy and heating properties QA of MRgHIFU system even in long-term use. Moreover, this simple QA method may be used to reveal small changes in HIFU performance assuring consistent functionality and safety of the MRgHIFU system.

  14. [Analysis of bactericidal material generated by electrical devices advertising bactericidal ability against bacteria on the agar gel plates].

    PubMed

    Nishimura, Hidekazu

    2012-11-01

    Several Japanese companies sell electrical devices advertised as effective in inactivating viruses and killing bacteria by releasing special materials, e.g., Plasmacluster ions, Nanoe particle and minus ions, into the air. These companies claim that their devices killed bacteria on plates in their own experiments. We tested device effectiveness using the same experiments from the Plasmacluster ioniser SHARP Co., Japan, the Nanoe generator Panasonic Co., Japan, and the Vion KING JIM Co., Japan, to test their advertising claims. Bactericidal ability on agar plate was tested, using Staphylococcus aureus, Pseudomonas aeruginosa, Bacillus cereus, and Enterococcus faecalis as follows: the medium containing a certain amount of each bacterium was put onto an agar plate and smeared. Plates were kept in a closed chamber (inner volume 14.4 m3) or a glove box (inner volume 0.2 m), with one of the devices run for 2 hours. Plates not exposed to any device were used as controls. Each plate was retrieved and put in an incubator to count the number of bacterial colonies formed on the plate. There was no significant difference in the number of colonies on plates exposed to devices compared to control, in the number for all devices, or in all bacteria tested in experiments in the 14.4 m3 chamber. These results strongly suggest that these devices have almost no bactericidal effect, at least in space exceeding this volume. Colony formation was suppressed in the glove box in all devices and in all bacteria tested except P. aeruginosa, although the degree of suppression differed among experiments. The colony formation suppression mechanism was analyzed, and indicated that:colony formation did not change even after the removal of Plasmacluster ions, Nanoe particles, or negative ions from the air, while colony formation was decreased drastically by the removal of ozone from space, which was revealed to be generated inevitably during device operation. These results strongly suggest that the

  15. Phenotypic Screening of Carbapenemases and Associated β-Lactamases in Carbapenem-Resistant Enterobacteriaceae

    PubMed Central

    Birgy, André; Bidet, Philippe; Genel, Nathalie; Doit, Catherine; Decré, Dominique; Arlet, Guillaume

    2012-01-01

    Dissemination of carbapenem resistance among Enterobacteriaceae poses a considerable threat to public health. Carbapenemase gene detection by molecular methods is the gold standard but is available in only a few laboratories. The aim of this study was to test phenotypic methods for the detection of metallo-β-lactamase (MBL)- or Klebsiella pneumoniae carbapenemase (KPC)-producing Enterobacteriaceae and associated mechanisms of β-lactam resistance against a panel of 30 genotypically characterized carbapenem-resistant Enterobacteriaceae : 9 MBL, 7 KPC, 6 OXA-48, and 8 extended-spectrum β-lactamase (ESBL) or AmpC β-lactamases associated with decreased permeability. We used carbapenemase inhibitor-impregnated agar to test for carbapenem-resistant strains. Differences in the inhibition zone sizes of the meropenem, imipenem, ertapenem, and doripenem disks were measured between control and inhibitor (EDTA or phenylboronic acid [PBA] with or without cloxacillin)-impregnated Mueller-Hinton agar with a cutoff of 10 mm. All 9 MBL- and 7 KPC-producing Enterobacteriaceae were identified from the differences in zone size in the presence and absence of specific inhibitors, regardless of the carbapenem MICs and including isolates with low-level resistance to carbapenems. We also detected their associated β-lactam resistance mechanisms (11 ESBL-type and 5 class A β-lactamase 2b). No differences in zone size were observed for OXA-48-producing strains or other carbapenem resistance mechanisms such as ESBL and decreased permeability. We propose a new strategy to detect carbapenemases (MBL- and KPC-type) and associated mechanisms of β-lactam resistance (ESBL or class A β-lactamase 2b) by the use of inhibitor-impregnated agar. A rapid phenotypic detection of resistance mechanisms is important for epidemiological purposes and for limiting the spread of resistant strains by implementing specific infection control measures. PMID:22259214

  16. Optimized In Vitro Antibiotic Susceptibility Testing Method for Small-Colony Variant Staphylococcus aureus

    PubMed Central

    Precit, Mimi R.; Wolter, Daniel J.; Griffith, Adam; Emerson, Julia; Burns, Jane L.

    2016-01-01

    Staphylococcus aureus small-colony variants (SCVs) emerge frequently during chronic infections and are often associated with worse disease outcomes. There are no standardized methods for SCV antibiotic susceptibility testing (AST) due to poor growth and reversion to normal-colony (NC) phenotypes on standard media. We sought to identify reproducible methods for AST of S. aureus SCVs and to determine whether SCV susceptibilities can be predicted on the basis of treatment history, SCV biochemical type (auxotrophy), or the susceptibilities of isogenic NC coisolates. We tested the growth and stability of SCV isolates on 11 agar media, selecting for AST 2 media that yielded optimal SCV growth and the lowest rates of reversion to NC phenotypes. We then performed disk diffusion AST on 86 S. aureus SCVs and 28 isogenic NCs and Etest for a subset of 26 SCVs and 24 isogenic NCs. Growth and reversion were optimal on brain heart infusion agar and Mueller-Hinton agar supplemented with compounds for which most clinical SCVs are auxotrophic: hemin, menadione, and thymidine. SCVs were typically nonsusceptible to either trimethoprim-sulfamethoxazole or aminoglycosides, in accordance with the auxotrophy type. In contrast, SCVs were variably nonsusceptible to fluoroquinolones, macrolides, lincosamides, fusidic acid, and rifampin; mecA-positive SCVs were invariably resistant to cefoxitin. All isolates (both SCVs and NCs) were susceptible to quinupristin-dalfopristin, vancomycin, minocycline, linezolid, chloramphenicol, and tigecycline. Analysis of SCV auxotrophy type, isogenic NC antibiograms, and antibiotic treatment history had limited utility in predicting SCV susceptibilities. With clinical correlation, this AST method and these results may prove useful in directing treatment for SCV infections. PMID:26729501

  17. Improved detection of vanB2-containing enterococcus faecium with vancomycin susceptibility by Etest using oxgall supplementation.

    PubMed

    Grabsch, E A; Chua, K; Xie, S; Byrne, J; Ballard, S A; Ward, P B; Grayson, M L

    2008-06-01

    We have isolated a number of vanB-containing Enterococcus faecium isolates on bile esculin screening agar containing 6 mg/liter vancomycin, which on subsequent susceptibility testing using Etest have repeatedly demonstrated vancomycin MICs of Mueller-Hinton agar (MHA) and brain heart infusion agar (BHIA) were supplemented with 10 g/liter oxgall (MHA-Oxg and BHIA-Oxg, respectively). We assessed the sensitivity and specificity of these media to detect vancomycin resistance using vancomycin-resistant vanB-containing E. faecium (n = 11), vancomycin-susceptible (van negative) E. faecium (n = 11), vancomycin-susceptible (van negative) E. faecalis (n = 11), and our LM-VRE (n = 23) isolates. After 48 h of incubation, both MHA-Oxg and BHIA-Oxg were 100% (34/34) sensitive and 100% (22/22) specific in the identification of vancomycin resistance. These findings suggest that supplementation of MHA or BHIA with 10 g/liter oxgall should be considered in laboratories where VRE detection protocols rely primarily on strain phenotype rather than early vanB gene detection by PCR.

  18. Colistin MIC Variability by Method for Contemporary Clinical Isolates of Multidrug-Resistant Gram-Negative Bacilli

    PubMed Central

    Hindler, Janet A.

    2013-01-01

    In vitro evaluation of colistin susceptibility is fraught with complications, due in part to the inherent cationic properties of colistin. In addition, no reference method has been defined against which to compare the results of colistin susceptibility testing. This study systematically evaluated the available methods for colistin MIC testing in two phases. In phase I, colistin MICs were determined in 107 fresh clinical isolates of multidrug-resistant (MDR) Gram-negative bacilli (GNB) by broth microdilution with polysorbate 80 (BMD-T), broth macrodilution (TDS), and the Etest. In phase II, 50 of these isolates, 10 of which were colistin resistant, were tested in parallel using BMD-T, TDS, agar dilution, broth microdilution without polysorbate 80 (BMD), and the TREK Gram-negative extra MIC format (GNXF) Sensititre. The Etest was also performed on these 50 isolates using Mueller-Hinton agar (MHA) from three different manufacturers. Colistin MIC results obtained from the five methods were compared to the MIC results obtained using BMD-T, the method that enables the highest nominal concentration of colistin in the test medium. Essential agreement ranged from 34% (BMD) to 83% (TDS), whereas categorical agreement was >90% for all methods except for BMD, which was 88%. Very major errors (VMEs) (i.e., false susceptibility) for the Etest were found in 47 to 53% of the resistant isolates, depending on the manufacturer of the MHA that was used. In contrast, VMEs were found for 10% (n = 1) of the resistant isolates by BMD and 0% of the isolates by the TDS, agar dilution, and Sensititre methods. Based on these data, we urge clinical laboratories to be aware of the variable results that can occur when using different methods for colistin MIC testing and, in particular, to use caution with the Etest. PMID:23486719

  19. Antibacterial activity of epidural infusions.

    PubMed

    Coghlan, M W; Davies, M J; Hoyt, C; Joyce, L; Kilner, R; Waters, M J

    2009-01-01

    The incidence of epidural abscess following epidural catheterisation appears to be increasing, being recently reported as one in 1000 among surgical patients. This study was designed to investigate the antibacterial activity of various local anaesthetics and additives, used in epidural infusions, against a range of micro-organisms associated with epidural abscess. The aim was to determine which, if any, epidural infusion solution has the greatest antibacterial activity. Bupivacaine, ropivacaine and levobupivacaine crystals were dissolved and added to Mueller-Hinton Agar in concentrations of 0.06%, 0.125%, 0.2%, 0.25%, 0.5% and 1%. Fentanyl, adrenaline and clonidine were also mixed with agar in isolation and in combination with the local anaesthetics. Using a reference agar dilution method, the minimum inhibitory concentrations were determined for a range of bacteria. Bupivacaine showed antibacterial activity against Staphylococcus aureus, Enterococcus faecalis and Escherichia coli with minimum inhibitory concentrations between 0.125% and 0.25%. It did not inhibit the growth of Pseudomonas aeruginosa at any of the concentrations tested. Levobupivacaine and ropivacaine showed no activity against Staphylococcus aureus, Enterococcus faecalis and Pseudomonas aeruginosa, even at the highest concentrations tested, and minimal activity against Escherichia coli (minimum inhibitory concentrations 0.5% and 1% respectively). The presence of fentanyl, adrenaline and clonidine had no additional effect on the antibacterial activity of any of the local anaesthetic agents. The low concentrations of local anaesthetic usually used in epidural infusions have minimal antibacterial activity. While the clinical implications of this in vitro study are not known, consideration should be given to increasing the concentration of bupivacaine in an epidural infusion or to administering a daily bolus of 0.25% bupivacaine to reduce the risk of epidural bacterial growth.

  20. Antimicrobial Susceptibility of Enteric Gram Negative Facultative Anaerobe Bacilli in Aerobic versus Anaerobic Conditions

    PubMed Central

    Amachawadi, Raghavendra G.; Renter, David G.; Volkova, Victoriya V.

    2016-01-01

    Antimicrobial treatments result in the host’s enteric bacteria being exposed to the antimicrobials. Pharmacodynamic models can describe how this exposure affects the enteric bacteria and their antimicrobial resistance. The models utilize measurements of bacterial antimicrobial susceptibility traditionally obtained in vitro in aerobic conditions. However, in vivo enteric bacteria are exposed to antimicrobials in anaerobic conditions of the lower intestine. Some of enteric bacteria of food animals are potential foodborne pathogens, e.g., Gram-negative bacilli Escherichia coli and Salmonella enterica. These are facultative anaerobes; their physiology and growth rates change in anaerobic conditions. We hypothesized that their antimicrobial susceptibility also changes, and evaluated differences in the susceptibility in aerobic vs. anaerobic conditions of generic E. coli and Salmonella enterica of diverse serovars isolated from cattle feces. Susceptibility of an isolate was evaluated as its minimum inhibitory concentration (MIC) measured by E-Test® following 24 hours of adaptation to the conditions on Mueller-Hinton agar, and on a more complex tryptic soy agar with 5% sheep blood (BAP) media. We considered all major antimicrobial drug classes used in the U.S. to treat cattle: β-lactams (specifically, ampicillin and ceftriaxone E-Test®), aminoglycosides (gentamicin and kanamycin), fluoroquinolones (enrofloxacin), classical macrolides (erythromycin), azalides (azithromycin), sulfanomides (sulfamethoxazole/trimethoprim), and tetracyclines (tetracycline). Statistical analyses were conducted for the isolates (n≥30) interpreted as susceptible to the antimicrobials based on the clinical breakpoint interpretation for human infection. Bacterial susceptibility to every antimicrobial tested was statistically significantly different in anaerobic vs. aerobic conditions on both media, except for no difference in susceptibility to ceftriaxone on BAP agar. A satellite experiment

  1. Application of in vitro soft agar techniques for growth of tumor cells to the study of colon cancer.

    PubMed

    Buick, R N; Fry, S E; Salmon, S E

    1980-03-15

    An in vitro assay to measure the clonogenic or colony-forming capability of cancer cells present in biopsy samples has recently been applied to study the biology and drug-sensitivity of a variety of human neoplasms. This approach appears to be suitable for study of the tumor stem or progenitor cells present in malignant effusions from patients with colonic carcinoma. In our preliminary studies, morphology of the tumor colonies by inverted microscopy and with Papanicolaou staining of dried agar plating layers as well as immunofluorescent localization with a specific antiserum to human carcinoembrionic antigen have been used as markers of the neoplastic origin of colon tumor colony-forming cells. Successful application of this assay to colonic solid tumors will require improvement in techniques for disaggregation of viable clonogenic cells. We anticipate that short term clonal assays will have increasing use for clinical and biological studies of human colon cancer.

  2. The agar diffusion scratch assay - A novel method to assess the bioactive and cytotoxic potential of new materials and compounds

    PubMed Central

    Pusnik, Mascha; Imeri, Minire; Deppierraz, Grégoire; Bruinink, Arie; Zinn, Manfred

    2016-01-01

    A profound in vitro evaluation not only of the cytotoxic but also of bioactive potential of a given compound or material is crucial for predicting potential effects in the in vivo situation. However, most of the current methods have weaknesses in either the quantitative or qualitative assessment of cytotoxicity and/or bioactivity of the test compound. Here we describe a novel assay combining the ISO 10993-5 agar diffusion test and the scratch also termed wound healing assay. In contrast to these original tests this assay is able to detect and distinguish between cytotoxic, cell migration modifying and cytotoxic plus cell migration modifying compounds, and this at higher sensitivity and in a quantitative way. PMID:26861591

  3. Biomimetic synthesis of hollow calcium carbonate with the existence of the agar matrix and bovine serum albumin.

    PubMed

    Feng, Jianhua; Wu, Gang; Qing, Chengsong

    2016-01-01

    Proteins play important roles in the process of biomineralization. Vaterite and calcite have been synthesized by the reaction of Na2CO3 and CaCl2 in the bovine serum albumin (BSA) and agar system. The samples have been characterized by Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD). The shape of CaCO3 crystal has been analyzed by scanning electronic microscopy (SEM). The results show that calcite is a single product in the absence of BSA, but the product is a mixture of calcite and vaterite in the presence of BSA. The spheral shell of CaCO3 crystal was obtained when the concentration of BSA increased to 9.0mg/mL.

  4. Effect of seaweed on mechanical, thermal, and biodegradation properties of thermoplastic sugar palm starch/agar composites.

    PubMed

    Jumaidin, Ridhwan; Sapuan, Salit M; Jawaid, Mohammad; Ishak, Mohamad R; Sahari, Japar

    2017-06-01

    The aim of this paper is to investigate the characteristics of thermoplastic sugar palm starch/agar (TPSA) blend containing Eucheuma cottonii seaweed waste as biofiller. The composites were prepared by melt-mixing and hot pressing at 140°C for 10min. The TPSA/seaweed composites were characterized for their mechanical, thermal and biodegradation properties. Incorporation of seaweed from 0 to 40wt.% has significantly improved the tensile, flexural, and impact properties of the TPSA/seaweed composites. Scanning electron micrograph of the tensile fracture showed homogeneous surface with formation of cleavage plane. It is also evident from TGA results that thermal stability of the composites were enhanced with addition of seaweed. After soil burial for 2 and 4 weeks, the biodegradation of the composites was enhanced with addition of seaweed. Overall, the incorporation of seaweed into TPSA enhances the properties of TPSA for short-life product application such as tray, plate, etc.

  5. Effects of extracellular matrix proteins on macrophage differentiation, growth, and function: comparison of liquid and agar culture systems

    NASA Technical Reports Server (NTRS)

    Armstrong, J. W.; Chapes, S. K.; Spooner, B. S. (Principal Investigator)

    1994-01-01

    Both spaceflight and skeletal unloading suppress the haematopoietic differentiation of macrophages (Sonnenfeld et al., Aviat. Space Environ. Med., 61:648-653, 1990; Armstrong et al., J. Appl. Physiol., 75:2734-2739, 1993). The mechanism behind this reduction in haematopoiesis has yet to be elucidated. However, changes in bone marrow extracellular matrix (ECM) may be involved. To further understand the role of ECM products in macrophage differentiation, we have performed experiments evaluating the effects of fibronectin, laminin, collagen type I, and collagen type IV on macrophage development and function. Bone marrow-derived macrophages cultured on four different ECM substrates in liquid culture medium showed less growth than those cultured on plastic. Significant morphological differences were seen on each of the substrates used. Phenotypically and functionally, as measured by class II major histocompatibility molecule (MHCII) expression, MAC-2 expression, and the secretion of interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-alpha), these macrophages were similar. In contrast, bone marrow-derived macrophages cultured in suspension, using agar, showed no difference in growth when exposed to ECM proteins. However, IL-6 and TNF-alpha secretion was affected by fibronectin, laminin, collagen type I, and collagen type IV in a concentration-dependent manner. We conclude that the ECM products fibronectin, laminin, collagen type I, and collagen type IV have profound effects on macrophage development and function. Additionally, we suggest that an ECM-supplemented agar culture system provides an environment more analogous to in vivo bone marrow than does a traditional liquid culture system.

  6. Equilibrium and kinetic modelling of Cd(II) biosorption by algae Gelidium and agar extraction algal waste.

    PubMed

    Vilar, Vítor J P; Botelho, Cidália M S; Boaventura, Rui A R

    2006-01-01

    In this study an industrial algal waste from agar extraction has been used as an inexpensive and effective biosorbent for cadmium (II) removal from aqueous solutions. This biosorbent was compared with the algae Gelidium itself, which is the raw material for agar extraction. Equilibrium data follow both Langmuir and Redlich-Peterson models. The parameters of Langmuir equilibrium model are q(max)=18.0 mgg(-1), b=0.19 mgl(-1) and q(max)=9.7 mgg(-1), b=0.16 mgl(-1), respectively for Gelidium and the algal waste. Kinetic experiments were conducted at initial Cd(II) concentrations in the range 6-91 mgl(-1). Data were fitted to pseudo-first- and second-order Lagergren models. For an initial Cd(II) concentration of 91 mgl(-1) the parameters of the pseudo-first-order Lagergren model are k(1,ads)=0.17 and 0.87 min(-1); q(eq)=16.3 and 8.7 mgg(-1), respectively, for Gelidium and algal waste. Kinetic constants vary with the initial metal concentration. The adsorptive behaviour of biosorbent particles was modelled using a batch reactor mass transfer kinetic model. The model successfully predicts Cd(II) concentration profiles and provides significant insights on the biosorbents performance. The homogeneous diffusivity, D(h), is in the range 0.5-2.2 x10(-8) and 2.1-10.4 x10(-8)cm(2)s(-1), respectively, for Gelidium and algal waste.

  7. Evaluation of potassium-clavulanate-supplemented modified charcoal-cefoperazone-deoxycholate agar for enumeration of Campylobacter in chicken carcass rinse.

    PubMed

    Chon, Jung-Whan; Kim, Hong-Seok; Kim, Hyunsook; Oh, Deog-Hwan; Seo, Kun-Ho

    2014-05-01

    Potassium-clavulanate-supplemented modified charcoal-cefoperazone-deoxycholate agar (C-mCCDA) that was described in our previous study was compared with original mCCDA for the enumeration of Campylobacter in pure culture and chicken carcass rinse. The quantitative detection of viable Campylobacter cells from a pure culture, plated on C-mCCDA, is statistically similar (P > 0.05) to mCCDA. In total, 120 chickens were rinsed using 400 mL buffered peptone water. The rinses were inoculated onto C-mCCDA and mCCDA followed by incubation at 42 °C for 48 h. There was no statistical difference between C-mCCDA (45 of 120 plates; mean count, 145.5 CFU/mL) and normal mCCDA (46 of 120 plates; mean count, 160.8 CFU/mL) in the isolation rate and recovery of Campylobacter (P > 0.05) from chicken carcass rinse. The Pearson correlation coefficient value for the number of Campylobacter cells recovered in the 2 media was 0.942. However, the selectivity was much better on C-mCCDA than on mCCDA plates (P < 0.05). Significantly fewer C-mCCDA plates (33 out of 120 plates; mean count, 1.9 CFU/mL) were contaminated with non-Campylobacter cells than the normal mCCDA plates (67 out of 120 plates; mean count, 27.1 CFU/mL). The C-mCCDA may provide improved results for enumeration of Campylobacter in chicken meat alternative to mCCDA with its increased selectivity the modified agar possess.

  8. Evaluation of the thin agar layer method for the recovery of pressure-injured and heat-injured Listeria monocytogenes.

    PubMed

    Lavieri, Nicolas A; Sebranek, Joseph G; Cordray, Joseph C; Dickson, James S; Jung, Stephanie; Manu, David K; Mendonça, Aubrey F; Brehm-Stecher, Byron F; Stock, Joseph; Stalder, Kenneth J

    2014-05-01

    A sublethally injured bacterial cell has been defined as a cell that survives a stress such as heating, freezing, acid treatment, or other antimicrobial intervention but can repair the cellular damage exerted by the stressor and later regain its original ability to grow. Consequently, sublethally injured cells are not likely to be included in conventional enumeration procedures, which could result in unrealistically low counts unless efforts are made to encourage recovery of the injured cells before enumeration. The objective of this study was to evaluate the use of the thin agar layer (TAL) method for the recovery of pressure-injured and heat-injured Listeria monocytogenes in a tryptic soy broth with 0.6% yeast extract system. Pressure injury consisted of treatment of a culture of mixed L. monocytogenes strains with high hydrostatic pressure at 400 or 600 MPa for 1 s, 2 min, 4 min, or 6 min at a process temperature of 12±2 °C. Heat injury consisted of treatment of a culture of mixed L. monocytogenes strains at 60±1 °C for 3, 6, or 9 min. Growth media were tryptic soy agar (TSA) with 0.6% yeast extract, modified Oxford medium (MOX), and TAL, which consisted of a 7-ml layer of TSA overlaid onto solidified MOX. Counts of viable L. monocytogenes on TAL were higher than those on MOX in the heat-injury experiment but not in the pressure-injury experiment. Therefore, the effectiveness of the TAL method may be specific to the type of injury applied to the microorganism and should be investigated in a variety of cellular injury scenarios.

  9. Reproducibility of control organism zone diameters for batches of IsoSensitest agar manufactured from 1996 to 2000 using the BSAC disc susceptibility test method.

    PubMed

    Landrygan, Janine; James, Peter A; Brooks, Dawn; Kubiak, Elizabeth M

    2002-02-01

    The BSAC Working Party on Susceptibility Testing has recently suggested that the performance of IsoSensitest agar has changed since 1991. Twenty batches of IsoSensitest agar that had been manufactured between 1996 and 2000 were tested using the BSAC standardized disc susceptibility testing method. Antibiotic discs containing amoxicillin 10 microg, ceftazidime 30 microg, gentamicin 10 microg, ciprofloxacin 1 microg and colistin sulphate 25 microg were tested on each batch of media 12 times against Escherichia coli ATCC 25922, Staphylococcus aureus ATCC 25923 and Pseudomonas aeruginosa ATCC 27853 where appropriate. There was a small reduction in zone sizes for most antibiotics on batches of media that were near their expiration date, but otherwise zone sizes were remarkably consistent. We could find no evidence to suggest that a change in the performance of IsoSensitest agar for the disc diffusion method had occurred since 1996.

  10. Comparison of eight different agars for the recovery of clinically relevant non-O157 Shiga toxin-producing Escherichia coli from baby spinach, cilantro, alfalfa sprouts and raw milk.

    PubMed

    Kase, Julie A; Maounounen-Laasri, Anna; Son, Insook; Lin, Andrew; Hammack, Thomas S

    2015-04-01

    The FDA Bacteriological Analytical Manual (BAM) Chapter 4a recommends several agars for isolating non-O157 Shiga toxin-producing Escherichia coli (STEC); not all have been thoroughly tested for recovering STECs from food. Using E. coli strains representing ten clinically relevant O serogroups (O26, O45, O91, O103, O104, O111, O113, O121, O128, O145) in artificially-contaminated fresh produce--bagged baby spinach, alfalfa sprouts, cilantro, and raw milk--we evaluated the performance of 8 different agars. Performance was highly dependent upon strain used and the presence of inhibitors, but not necessarily dependent on food matrix. Tellurite resistant-negative strains, O91:-, O103:H6, O104:H21, O113:H21, and O128, grew poorly on CHROMagar STEC, Rainbow agar O157, and a modified Rainbow O157 (mRB) agar. Although adding washed sheep's blood to CHROMagar STEC and mRB agars improved overall performance; however, this also reversed the inhibition of non-target bacteria provided by original formulations. Variable colony coloration made selecting colonies from Rainbow agar O157 and mRB agars difficult. Study results support a strategy using inclusive agars (e.g. L-EMB, SHIBAM) in combination with selective agars (R & F E. coli O157:H7, CHROMagar STEC) to allow for recovery of the most STECs while increasing the probability of recovering STEC in high bacterial count matrices.

  11. Strain-rate and temperature dependent material properties of Agar and Gellan Gum used in biomedical applications.

    PubMed

    Schiavi, Alessandro; Cuccaro, Rugiada; Troia, Adriano

    2016-01-01

    Agar and Gellan Gum are biocompatible polymers extensively used in several fields of tissue engineering research (e.g. tissue replacement, tissue support, tissue mimicking), due to their mechanical behaviour effectively representative of actual biological tissues. Since mechanical properties of artificial tissues are related to biocompatibility and functionality of medical implants and significantly influence adhesion, growth and differentiation of cells in tissue-engineering scaffolds, an accurate characterization of Young׳s modulus and relaxation time processes is needed. In this study, the strain-rate and temperature dependent material properties of Agarose and one among the numerous kind of Gellan Gum commercially available, known as Phytagel(®), have been investigated. Nine hydrogel samples have been realized with different mechanical properties: the first one Agar-based as a reference material, the further eight samples Gellan Gum based in which the effect of dispersed solid particles like kieselguhr and SiC, as enhancing mechanical properties factors, have been investigated as a function of concentration. Stress-strain has been investigated in compression and relaxation time has been evaluated by means of the Kohlrausch-Williams-Watts time decay function. Mechanical properties have been measured as a function of temperature between 20 °C and 35 °C and at different strain rates, from ~10(-3)s(-1) and ~10(-2)s(-1) (or deformation rate from ~0.01 mms(-1) to ~0.1 mms(-1)). From experimental data, the combined temperature and strain-rate dependence of hydrogels Young׳s modulus is determined on the basis of a constitutive model. In addition to a dependence of Young׳s modulus on temperature, a remarkable influence of strain-rate has been observed, especially in the sample containing solid particles; in same ranges of temperature and strain-rate, also relaxation time variations have been monitored in order to identify a possible dependence of damping

  12. Evaluation of an immunochromatographic assay for direct identification of thermostable direct hemolysin-producing Vibrio parahaemolyticus colonies on selective agar plates.

    PubMed

    Kawatsu, Kentaro; Sakata, Junko; Yonekita, Taro; Kumeda, Yuko

    2015-12-01

    We evaluated the utility of an immunochromatographic assay (NH IC TDH) in identifying thermostable direct hemolysin (TDH)-producing Vibrio parahaemolyticus colonies on selective agar plates. The sensitivity of the NH IC TDH assay was 100% (189 samples) and its specificity was 100% (41 samples) compared with the presence of tdh.

  13. Experimenting with a Visible Copper-Aluminum Displacement Reaction in Agar Gel and Observing Copper Crystal Growth Patterns to Engage Student Interest and Inquiry

    ERIC Educational Resources Information Center

    Xu, Xinhua; Wu, Meifen; Wang, Xiaogang; Yang, Yangyiwei; Shi, Xiang; Wang, Guoping

    2016-01-01

    The reaction process of copper-aluminum displacement in agar gel was observed at the microscopic level with a stereomicroscope; pine-like branches of copper crystals growing from aluminum surface into gel at a constant rate were observed. Students were asked to make hypotheses on the pattern formation and design new research approaches to prove…

  14. Characterization of a novel alkaline arylsulfatase from Marinomonas sp. FW-1 and its application in the desulfation of red seaweed agar.

    PubMed

    Wang, Xueyan; Duan, Delin; Xu, Jiachao; Gao, Xin; Fu, Xiaoting

    2015-10-01

    A bacterial strain capable of hydrolyzing sulfate ester bonds of p-nitrophenyl sulfate (pNPS) and agar was isolated from the coast area of Qingdao, China. It was identified as Marinomonas based on its 16S rRNA gene sequence and named as Marinomonas sp. FW-1. An arylsulfatase with a recovery of 13 % and a fold of 12 was purified to a homogeneity using ion exchange and gel filtration chromatographies. The enzyme was composed of a single polypeptide chain with the molecular mass of 33 kDa estimated using SDS-PAGE. The optimal pH and temperature of arylsulfatase were pH 9.0 and 45, respectively. Arylsulfatase was stable over pH 8-11 and at temperature below 55 °C. The K m and V max of this enzyme for the hydrolysis of pNPS were determined to be 13.73 and 270.27 μM/min, respectively. The desulfation ratio against agar from red seaweed Gelidium amansii and Gracilaria lemaneiformis were 86.11 and 89.61 %, respectively. There was no difference between the DNA electrophoresis spectrum on the gel of the arylsulfatase-treated G. amansii agar and that of the commercial agarose. Therefore, this novel alkaline arylsulfatase might have a great potential for application in enzymatic conversion of agar to agarose.

  15. A comparison of a new centrifuge sugar flotation technique with the agar method for the extraction of immature Culicoides (Diptera: Ceratopogonidae) life stages from salt marsh soils.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Two sampling techniques, agar extraction (AE) and centrifuge sugar flotation extraction (CSFE) were compared to determine their relative efficacy to recover immature stages of Culicoides spp from salt marsh substrates. Three types of samples (seeded with known numbers of larvae, homogenized field s...

  16. Use of agar diffusion assay to measure bactericidal activity of alkaline salts of fatty acids against bacteria associated with poultry processing

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The agar diffusion assay was used to examine antibacterial activity of alkaline salts of caproic, caprylic, capric, lauric, and myristic acids. A 0.5M concentration of each fatty acid was dissolved in 1.0 M potassium hydroxide (KOH), and pH of the mixtures was adjusted to 10.5 with citric acid. Solu...

  17. Comparative assessment of antimicrobial efficacy of different hand sanitizers: An in vitro study

    PubMed Central

    Jain, Vardhaman Mulchand; Karibasappa, Gundabaktha Nagappa; Dodamani, Arun Suresh; Prashanth, Vishwakarma K.; Mali, Gaurao Vasant

    2016-01-01

    Background: To evaluate the antimicrobial efficacy of four different hand sanitizers against Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa, Escherichia coli, and Enterococcus faecalis as well as to assess and compare the antimicrobial effectiveness among four different hand sanitizers. Materials and Methods: The present study is an in vitro study to evaluate antimicrobial efficacy of Dettol, Lifebuoy, PureHands, and Sterillium hand sanitizers against clinical isolates of the aforementioned test organisms. The well variant of agar disk diffusion test using Mueller-Hinton agar was used for evaluating the antimicrobial efficacy of hand sanitizers. McFarland 0.5 turbidity standard was taken as reference to adjust the turbidity of bacterial suspensions. Fifty microliters of the hand sanitizer was introduced into each of the 4 wells while the 5th well incorporated with sterile water served as a control. This was done for all the test organisms and plates were incubated in an incubator for 24 h at 37΀C. After incubation, antimicrobial effectiveness was determined using digital caliper (mm) by measuring the zone of inhibition. Results: The mean diameters of zones of inhibition (in mm) observed in Group A (Sterillium), Group B (PureHands), Group C (Lifebuoy), and Group D (Dettol) were 22 ± 6, 7.5 ± 0.5, 9.5 ± 1.5, and 8 ± 1, respectively. Maximum inhibition was found with Group A against all the tested organisms. Data were statistically analyzed using analysis of variance, followed by post hoc test for group-wise comparisons. The difference in the values of different sanitizers was statistically significant at P < 0.001. Conclusion: Sterillium was the most effective hand sanitizer to maintain the hand hygiene. PMID:27857768

  18. In Vitro Susceptibility of Mycobacterium ulcerans to Clarithromycin

    PubMed Central

    Portaels, F.; Traore, H.; De Ridder, K.; Meyers, W. M.

    1998-01-01

    Buruli ulcer (BU), caused by Mycobacterium ulcerans, was recently recognized by the World Health Organization as an important emerging disease. While antimycobacterial therapy is often effective for the earliest nodular or ulcerative lesions, medical management of BU lesions in patients presenting for treatment is usually disappointing, leaving wide surgical excision the only alternative. Advanced ulcerated lesions of BU rarely respond to antimycobacterial agents; however, perioperative administration of such drugs may prevent relapses or disseminated infections. Clarithromycin possesses strong activity in vitro and in vivo against most nontuberculous mycobacteria. In this study we determined the antimycobacterial activity of this drug in vitro against 46 strains of M. ulcerans isolated from 11 countries. The MIC of clarithromycin was determined at pH 6.6 (on 7H11 agar) and at pH 7.4 (on Mueller-Hinton agar). The MICs ranged from 0.125 to 2 μg/ml at pH 6.6 and from <0.125 to 0.5 μg/ml at pH 7.4. For the majority of the strains, geographic origin did not play a significant role. Thirty-eight strains (83%) were inhibited by 0.5 μg/ml at pH 7.4. These MICs are below peak therapeutic concentrations of clarithromycin obtainable in blood. These results suggest that clarithromycin is a promising drug both for the treatment of early lesions of M. ulcerans and for the prevention of hematogenous dissemination of the etiologic agent during and after surgery. Studies should be initiated to evaluate the effects of clarithromycin in combination with ethambutol and rifampin on M. ulcerans both in vitro and in experimentally infected mice. Multidrug regimens containing clarithromycin may also help control the secondary bacterial infections sometimes seen in BU patients, most importantly osteomyelitis. PMID:9687409

  19. Approach to Carbapenemase Detection in Klebsiella pneumoniae in Routine Diagnostic Laboratories

    PubMed Central

    Shenoy, Shalini; Mala, Suchitra Shenoy; Baliga, Shrikala; Ashish, Agarwal

    2016-01-01

    Introduction Resistance to Carbapenems in Klebsiella may be due to Carbapenem hydrolysing enzymes. Accurate detection of carbapenemase must be done for patient treatment and epidemiological purposes. Aim To detect carbapenemase production by performing Modified Hodge Test (MHT), Combined Disk Test (CDT) for Metallo-β-Lactamases (MBL) and PCR for blaKPC gene, to evaluate the performance of MHT using MacConkey Agar (MCA) and to access the value of MHT for carbapenemase detection. Material and Methods Using a prospective laboratory study design, 153 Extended Spectrum Beta-Lactamases (ESBL) producing Klebsiella pneumoniae from clinical samples of patients admitted in the Kasturba Medical College were collected from January 2014 to December 2015. Isolates resistant to carbapenems by disk diffusion were subjected to MHT on MCA and Mueller Hinton agar (MHA). All isolates were tested for (MBL) production by Imipenem and Imipenem-EDTA CDT and subjected to PCR for the presence of blaKPC gene. Results Out of 153 isolates, 54 were resistant to one of the carbapenems. Among these, 13 were positive for MHT on MHA, while 23 were positive by MHT on MCA. Number of MBL producers was 23 (42.5%), while blaKPC was detected in 2 out of the 54 isolates. Conclusion Though detection of drug resistance gene remains the method of choice, it can be performed only in centers with adequate resources. Hence, for most laboratories in resource poor countries, the MHT performed on MCA with concomitant CDT for MBL detection seem to be a better option for detection of Carbapenem resistance. PMID:28208858

  20. Further Modification of the Modified Hodge Test for Detecting Metallo-β-Lactamase-Producing Carbapenem-Resistant Enterobacteriaceae

    PubMed Central

    Kim, Hyun-Ki; Park, Jeong Su; Sung, Heungsup

    2015-01-01

    Background The modified Hodge test (MHT) was designed to detect carbapenemase-producing Enterobacteriaceae (CPE). This study evaluated variables to improve the performance of MHT. Methods Carbapenem-resistant Enterobacteriaceae isolated from November 2010 to March 2013 at the Asan Medical Center, were evaluated, including 33 metallo-β-lactamase (MBL) producers and 103 non-CPEs. MHT was performed by using two carbapenem disks (ertapenem and meropenem; Becton Dickinson, USA), three media (Mueller-Hinton agar (MHA), MacConkey agar (MAC), and zinc-enriched MHA), and two inoculums (0.5-McFarland [McF] suspension and a 10-fold dilution of it.) PCR was performed to detect β-lactamase genes of the MBL, AmpC, and CTX-M types. Results The sensitivity of MHT for detecting New Delhi metallo-β-lactamase (NDM) producers was highest using ertapenem and 0.5-McF, 52.0% on MHA and 68.0% on MAC, respectively. NDM-producing Klebsiella pneumoniae (NDMKP) were detected with higher sensitivity on MAC (78.6%) vs. MHA (28.6%) (P=0.016), but VIM-producing Enterobacter, Citrobacter, and Serratia were detected with higher sensitivity on MHA (78.5%) vs. MAC (14.3%) (P=0.004). MBL producers were consistently identified with lower sensitivity using meropenem vs. ertapenem, 39.4% vs. 60.6% (P=0.0156), respectively. The effects of zinc and inoculum size were insignificant. Enterobacter aerogenes producing unspecified AmpC frequently demonstrated false positives, 66.7% with ertapenem and 22.2% with meropenem. Conclusions The MHT should be adjusted for the local distribution of species and the carbapenemase type of MBL producers. MAC and ertapenem are preferable for assessing NDMKP, but MHA is better for VIM. Laboratory physicians should be aware of the limited sensitivity of MHT and its relatively high false-positive rate. PMID:25932437

  1. Influence of penicillin/amoxicillin non-susceptibility on the activity of third-generation cephalosporins against Streptococcus pneumoniae.

    PubMed

    Fenoll, A; Giménez, M J; Robledo, O; Aguilar, L; Tarragó, D; Granizo, J J; Martín-Herrero, J E

    2008-01-01

    To study the influence of penicillin/amoxicillin non-susceptibility on the activity of third-generation cephalosporins, 430 consecutive penicillin non-susceptible Streptococcus pneumoniae 2007 isolates received in the Spanish Reference Pneumococcal Laboratory were tested. For comparative purposes, 625 penicillin-susceptible 2007 isolates were also tested. Susceptibility was determined by agar dilution using Mueller-Hinton agar supplemented with 5% sheep blood. Penicillin-susceptible strains were susceptible to amoxicillin, cefotaxime and ceftriaxone, 99.8% to cefpodoxime and 99.5% to cefdinir, and were inhibited by 0.12 microg/ml of cefditoren and 4 microg/ml of cefixime. Penicillin-intermediate strains were susceptible to cefotaxime and ceftriaxone, with <50% susceptibility to cefdinir and cefpodoxime. The MIC(50) and MIC(90) values of cefditoren were 0.25 microg/ml and 0.5 microg/ml, respectively, whereas cefixime exhibited only marginal activity (MIC(90)=16 microg/ml). Penicillin-resistant strains were resistant to cefdinir and cefpodoxime, with 74.8% and 94.1% susceptibility to cefotaxime and ceftriaxone, respectively. Cefditoren MIC(50)/MIC(90) (0.5/1 microg/ml) were lower than cefotaxime and ceftriaxone. Among amoxicillin non-susceptible strains, susceptibility to cefdinir and cefpodoxime was <10%, and susceptibility to cefotaxime decreased from 87.9% in the intermediate category to 63.0% in the resistant group. Cefditoren MIC(50)/MIC(90) (0.5/1 microg/ml) were lower than cefotaxime. In conclusion, the activity of cefixime, cefdinir and cefpodoxime was highly affected by penicillin/amoxicillin non-susceptibility, while parenteral third-generation cephalosporins exhibited higher intrinsic activity (MIC(90)=1 microg/ml for penicillin-resistant and 2 microg/ml for amoxicillin-resistant strains). Cefditoren exhibited one-dilution lower MIC(90) values for these strains, even against those of the most troublesome serotypes.

  2. Evaluation of liquid and solid culture media for the recovery and enrichment of Burkholderia cenocepacia from distilled water.

    PubMed

    Ahn, Youngbeom; Kim, Jeong Myeong; Ahn, Hyeri; Lee, Yong-Jin; LiPuma, John J; Hussong, David; Cerniglia, Carl E

    2014-07-01

    Burkholderia cepacia complex (BCC) presence has been the cause of recalls of both sterile and non-sterile pharmaceutical products since these opportunistic pathogens have been implicated to cause infections to susceptible individuals. BCC are ubiquitous in nature, but in pharmaceutical settings the most common source is contaminated water systems. Some strains of BCC, previously described as Pseudomonas cepacia, were not readily detected by standard culture methods. We have explored different strategies to recover and enrich Burkholderia cenocepacia previously cultured in distilled water for 40 days. Enrichment media of varied nutrient concentrations and composition were used, including modified Tryptic Soy Agar or Broth (TSA or TSB), Reasoner's 2nd Agar or Broth (R2A or R2AB), Brain-Heart Infusion Broth (BHIB), Mueller-Hinton Broth (MHB), and Ashdown's (ASH) medium. Of the various broth media tested, cell growth was significantly greater in TSB and R2AB than in BHIB, MHB, or ASH broth. TSB and R2AB were also compared for their recovery efficiency. Generally, there was no significant difference between the numbers of B. cenocepacia grown on 15 differently modified TSA and five modified R2A solid media. Overall, however, diluted TSA and TSB media, and R2A and R2AB showed better recovery efficiency than TSA and TSB for inocula containing small numbers of cells. All strains persisted in distilled water for 40 days. Broth media were more effective than solid media for recovery of B. cenocepacia from distilled water. These results may assist in improving detection assays with recovery and enrichment strategies to maximize recovery of these fastidious organisms.

  3. DETERMINATION OF THE MAXIMUM INHIBITORY DILUTION OF CETYLPYRIDINIUM CHLORIDE-BASED MOUTHWASHES AGAINST STAPHYLOCOCCUS AUREUS: AN IN VITRO STUDY

    PubMed Central

    Watanabe, Evandro; Tanomaru, Juliane Maria Guerreiro; Nascimento, Andresa Piacezzi; Matoba, Fumio; Tanomaru, Mario; Ito, Izabel Yoko

    2008-01-01

    The aim of this in vitro study was to determine the maximum inhibitory dilution (MID) of four cetylpyridinium chloride (CPC)-based mouthwashes: CPC+Propolis, CPC+Malva, CPC+Eucaliptol+Juá+Romã+Propolis (Natural Honey®) and CPC (Cepacol®), against 28 Staphylococcus aureus field strains, using the agar dilution method. Decimal dilutions ranging from 1/10 to 1/ 655,360 were prepared and added to Mueller Hinton Agar. Strains were inoculated using Steers multipoint inoculator. The inocula were seeded onto the surface of the culture medium in Petri dishes containing different dilutions of the mouthwashes. The dishes were incubated at 37°C for 24 h. For readings, the MID was considered as the maximum dilution of mouthwash still capable of inhibiting microbial growth. The obtained data showed that CPC+Propolis had antimicrobial activity against 27 strains at 1/320 dilution and against all 28 strains at 1/160 dilution, CPC+Malva inhibited the growth of all 28 strains at 1/320 dilution, CPC+Eucaliptol+Juá+Romã+Propolis inhibited the growth of 2 strains at 1/640 dilution and all 28 strains at 1/320 dilution, and Cepacol® showed antimicrobial activity against 3 strains at 1/320 dilution and against all 28 strains at 1/160 dilution. Data were submitted to Kruskal-Wallis test, showing that the MID of Cepacol® was lower than that determined for the other products (p<0.05). In conclusion, CPC-mouthwashes showed antimicrobial activity against S. aureus and the addition of other substances to CPC improved its antimicrobial effect. PMID:19089260

  4. Antibacterial activity of silver bionanocomposites synthesized by chemical reduction route

    PubMed Central

    2012-01-01

    Background The aim of this study is to investigate the functions of polymers and size of nanoparticles on the antibacterial activity of silver bionanocomposites (Ag BNCs). In this research, silver nanoparticles (Ag NPs) were incorporated into biodegradable polymers that are chitosan, gelatin and both polymers via chemical reduction method in solvent in order to produce Ag BNCs. Silver nitrate and sodium borohydride were employed as a metal precursor and reducing agent respectively. On the other hand, chitosan and gelatin were added as a polymeric matrix and stabilizer. The antibacterial activity of different sizes of silver nanoparticles was investigated against Gram-positive and Gram-negative bacteria by the disk diffusion method using Mueller-Hinton Agar. Results The properties of Ag BNCs were studied as a function of the polymer weight ratio in relation to the use of chitosan and gelatin. The morphology of the Ag BNCs films and the distribution of the Ag NPs were also characterized. The diameters of the Ag NPs were measured and their size is less than 20 nm. The antibacterial trait of silver/chitosan/gelatin bionanocomposites was investigated. The silver ions released from the Ag BNCs and their antibacterial activities were scrutinized. The antibacterial activities of the Ag BNC films were examined against Gram-negative bacteria (E. coli and P. aeruginosa) and Gram-positive (S. aureus and M. luteus) by diffusion method using Muller-Hinton agar. Conclusions The antibacterial activity of Ag NPs with size less than 20 nm was demonstrated and showed positive results against Gram-negative and Gram-positive bacteria. The Ag NPs stabilized well in the polymers matrix. PMID:22967920

  5. Simple screening method for gram-positive bacterial beta-lactam antibiotic tolerance on routine laboratory Bauer-Kirby antibiogram plates.

    PubMed

    Traub, W H

    1982-01-01

    A simple screening method served to detect beta-lactam antibiotic-tolerant variants of clinical isolates and laboratory control strains of staphylococcus aureus, S. epidermis, group B beta-hemolytic streptococci, and Listeria monocytogenes. The beta-lactamase(s) of a multiple drug-resistant strain of Enterobacter cloacae (isolate No. 19) yielded most consistent results as compared with several other beta-lactamase producers; the E. cloacae beta-lactamase(s) was neutralized by clavulanic acid. Spot inocula of E. cloacae isolate No. 19, following overnight "induction" with 1 microgram/ml of ampicillin and 3 microgram/ml of cephalothin in tryptic soya broth, were applied centrally to beta-lactam antibiotic inhibition zones of Bauer-Kirby antibiogram plates (Mueller-Hinton agar, MHA, and diagnostic sensitivity test agar, DSTA) following removal of the appropriate disks. The spot-inoculated plates were incubated overnight at 35 degrees C and inspected for satellite growths of tolerant variants around the E. cloacae spot inocula. Satellite growths of less than or equal to 10 colonies were interpreted to indicate tolerance of the relevant cell wall synthesis inhibitor. The method readily permitted detection of variants tolerant for ampicillin, cephalothin, penicillin G, piperacillin, azlocillin, and mezlocillin. However, strains documented by minimal inhibitory and minimal bactericidal concentrations to be tolerant for cefotaxime, cefoxitin, fosfomycin, and vancomycin only rarely gave rise to respective satellite growths. DSTA proved superior to MHA with respect to "rescue" of inhibited tolerant staphylococcal variants; furthermore, the diameters of inhibition zones obtained on DSTA correlated well with those on MHA. Therefore, DSTA was adopted as the routine test medium for clinical staphylococcal isolates.

  6. Kinetics and equilibrium modelling of lead uptake by algae Gelidium and algal waste from agar extraction industry.

    PubMed

    Vilar, Vítor J P; Botelho, Cidália M S; Boaventura, Rui A R

    2007-05-08

    Pb(II) biosorption onto algae Gelidium, algal waste from agar extraction industry and a composite material was studied. Discrete and continuous site distribution models were used to describe the biosorption equilibrium at different pH (5.3, 4 and 3), considering competition among Pb(II) ions and protons. The affinity distribution function of Pb(II) on the active sites was calculated by the Sips distribution. The Langmuir equilibrium constant was compared with the apparent affinity calculated by the discrete model, showing higher affinity for lead ions at higher pH values. Kinetic experiments were conducted at initial Pb(II) concentrations of 29-104 mgl(-1) and data fitted to pseudo-first Lagergren and second-order models. The adsorptive behaviour of biosorbent particles was modelled using a batch mass transfer kinetic model, which successfully predicts Pb(II) concentration profiles at different initial lead concentration and pH, and provides significant insights on the biosorbents performance. Average values of homogeneous diffusivity, D(h), are 3.6 x 10(-8); 6.1 x 10(-8) and 2.4 x 10(-8)cm(2)s(-1), respectively, for Gelidium, algal waste and composite material. The concentration of lead inside biosorbent particles follows a parabolic profile that becomes linear near equilibrium.

  7. Multicenter Evaluation of MRSASelect II Chromogenic Agar for Identification of Methicillin-Resistant Staphylococcus aureus from Wound and Nasal Specimens.

    PubMed

    Hernandez, Diana R; Newton, Duane W; Ledeboer, Nathan A; Buchan, Blake; Young, Carol; Clark, Andrew E; Connoly, Jessica; Wolk, Donna M

    2016-02-01

    Hospitals strive to reduce methicillin-resistant Staphylococcus aureus (MRSA) prevalence via active surveillance of inpatient populations. Rapid and inexpensive screening methods are utilized when molecular methods are not operationally feasible. In this multisite clinical trial, the utility of Bio-Rad's MRSASelect II was evaluated for MRSA identification from remnant nares and wound swabs. The prevalence of MRSA was 11.1% (n = 1,384) from nares samples and 18.1% (n = 842) from wound samples. MRSASelect II had an overall concordance of 95.4% (confidence interval [CI] = 94.5% to 96.2%) compared to a broth-enriched reference standard. Comparisons between results, stratified by examination times, exhibited a nonsignificant trend toward increased positivity at prolonged incubation times. Cefoxitin screening of colonies directly from MRSASelect II was 96.7% (95.8% to 97.3%) concordant compared to testing of colonies following broth enrichment. A comparison of MRSASelect and MRSASelect II revealed no statistical differences; however, the latter exhibited earlier positivity, greater selectivity, and more intense indicator staining, which resulted in facilitated differentiation of positive results. MRSASelect II agar is a simple, rapid, and robust method to routinely screen patients for MRSA colonization without the need for additional testing.

  8. Thermal, mechanical, and physical properties of seaweed/sugar palm fibre reinforced thermoplastic sugar palm Starch/Agar hybrid composites.

    PubMed

    Jumaidin, Ridhwan; Sapuan, Salit M; Jawaid, Mohammad; Ishak, Mohamad R; Sahari, Japar

    2017-04-01

    The aim of this research is to investigate the effect of sugar palm fibre (SPF) on the mechanical, thermal and physical properties of seaweed/thermoplastic sugar palm starch agar (TPSA) composites. Hybridized seaweed/SPF filler at weight ratio of 25:75, 50:50 and 75:25 were prepared using TPSA as a matrix. Mechanical, thermal and physical properties of hybrid composites were carried out. Obtained results indicated that hybrid composites display improved tensile and flexural properties accompanied with lower impact resistance. The highest tensile (17.74MPa) and flexural strength (31.24MPa) was obtained from hybrid composite with 50:50 ratio of seaweed/SPF. Good fibre-matrix bonding was evident in the scanning electron microscopy (SEM) micrograph of the hybrid composites' tensile fracture. Fourier transform infrared spectroscopy (FT-IR) analysis showed increase in intermolecular hydrogen bonding following the addition of SPF. Thermal stability of hybrid composites was enhanced, indicated by a higher onset degradation temperature (259°C) for 25:75 seaweed/SPF composites than the individual seaweed composites (253°C). Water absorption, thickness swelling, water solubility, and soil burial tests showed higher water and biodegradation resistance of the hybrid composites. Overall, the hybridization of SPF with seaweed/TPSA composites enhances the properties of the biocomposites for short-life application; that is, disposable tray, plate, etc.

  9. Mutations in Arabidopsis thaliana genes involved in the tryptophan biosynthesis pathway affect root waving on tilted agar surfaces

    NASA Technical Reports Server (NTRS)

    Rutherford, R.; Gallois, P.; Masson, P. H.

    1998-01-01

    Arabidopsis thaliana roots grow in a wavy pattern upon a slanted surface. A novel mutation in the anthranilate synthase alpha 1 (ASA1) gene, named trp5-2wvc1, and mutations in the tryptophan synthase alpha and beta 1 genes (trp3-1 and trp2-1, respectively) confer a compressed root wave phenotype on tilted agar surfaces. When trp5-2wvc1 seedlings are grown on media supplemented with anthranilate metabolites, their roots wave like wild type. Genetic and pharmacological experiments argue that the compressed root wave phenotypes of trp5-2wvc1, trp2-1 and trp3-1 seedlings are not due to reduced IAA biosynthetic potential, but rather to a deficiency in L-tryptophan (L-Trp), or in a L-Trp derivative. Although the roots of 7-day-old seedlings possess higher concentrations of free L-Trp than the shoot as a whole, trp5-2wvc1 mutants show no detectable alteration in L-Trp levels in either tissue type, suggesting that a very localized shortage of L-Trp, or of a L-Trp-derived compound, is responsible for the observed phenotype.

  10. Correlation between Agar Plate Screening and Solid-State Fermentation for the Prediction of Cellulase Production by Trichoderma Strains

    PubMed Central

    Florencio, Camila; Couri, Sonia; Farinas, Cristiane Sanchez

    2012-01-01

    The viability of converting biomass into biofuels and chemicals still requires further development towards the reduction of the enzyme production costs. Thus, there is a growing demand for the development of efficient procedures for selection of cellulase-producing microorganisms. This work correlates qualitative screening using agar plate assays with quantitative measurements of cellulase production during cultivation under solid-state fermentation (SSF). The initial screening step consisted of observation of the growth of 78 preselected strains of the genus Trichoderma on plates, using microcrystalline cellulose as carbon source. The 49 strains that were able to grow on this substrate were then subjected to a second screening step using the Congo red test. From this test it was possible to select 10 strains that presented the highest enzymatic indices (EI), with values ranging from 1.51 to 1.90. SSF cultivations using sugarcane bagasse and wheat bran as substrates were performed using selected strains. The CG 104NH strain presented the highest EGase activity (25.93 UI·g−1). The EI results obtained in the screening procedure using plates were compared with cellulase production under SSF. A correlation coefficient (R2) of 0.977 was obtained between the Congo red test and SSF, demonstrating that the two methodologies were in good agreement. PMID:23227312

  11. Development and Validation of a Successful Microbiological Agar Assay for Determination of Ceftriaxone Sodium in Powder for Injectable Solution

    PubMed Central

    Aléssio, Patrícia V.; Salgado, Hérida R. N.

    2012-01-01

    Ceftriaxone sodium is a cephalosporin with broad-spectrum antimicrobial activity and belongs to the third generation of cephalosporins. Regarding the quality control of medicines, a validated microbiological assay for the determination of ceftriaxone sodium in powder for injectable solution has not been reported yet. This paper reports the development and validation of a simple, accurate and reproducible agar diffusion method to quantify ceftriaxone sodium in powder for injectable solution. The assay is based on the inhibitory effect of ceftriaxone sodium on the strain of Bacillus subtilis ATCC 9371 IAL 1027 used as test microorganism. The results were treated statistically by analysis of variance and were found to be linear (r = 0.999) in the selected range of 15.0–60.0 μg/mL, precise with a relative standard deviation (RSD) of repeatability intraday = 1.40%, accurate (100.46%) and robust with a RSD lower than 1.28%. The results demonstrated the validity of the proposed bioassay, which allows reliable ceftriaxone sodium quantitation in pharmaceutical samples and therefore can be used as a useful alternative methodology for the routine quality control of this medicine. PMID:24300294

  12. Analysis of Keystone Enzyme in Agar Hydrolysis Provides Insight into the Degradation (of a Polysaccharide from) Red Seaweeds*

    PubMed Central

    Hehemann, Jan-Hendrik; Smyth, Leo; Yadav, Anuj; Vocadlo, David J.; Boraston, Alisdair B.

    2012-01-01

    Agars are abundant polysaccharides from marine red algae, and their chemical structure consists of alternating d-galactose and 3,6-anhydro-l-galactose residues, the latter of which are presumed to make the polymer recalcitrant to degradation by most terrestrial bacteria. Here we study a family 117 glycoside hydrolase (BpGH117) encoded within a recently discovered locus from the human gut bacterium Bacteroides plebeius. Consistent with this locus being involved in agarocolloid degradation, we show that BpGH117 is an exo-acting 3,6-anhydro-α-(1,3)-l-galactosidase that removes the 3,6-anhydrogalactose from the non-reducing end of neoagaro-oligosaccharides. A Michaelis complex of BpGH117 with neoagarobiose reveals the distortion of the constrained 3,6-anhydro-l-galactose into a conformation that favors catalysis. Furthermore, this complex, supported by analysis of site-directed mutants, provides evidence for an organization of the active site and positioning of the catalytic residues that are consistent with an inverting mechanism of catalysis and suggests that a histidine residue acts as the general acid. This latter feature differs from the vast majority of glycoside hydrolases, which use a carboxylic acid, highlighting the alternative strategies that enzymes may utilize in catalyzing the cleavage of glycosidic bonds. PMID:22393053

  13. Improvement of mannitol lysine crystal violet brilliant green agar for the selective isolation of H2S-positive Salmonella.

    PubMed

    Kodaka, H; Mizuochi, S; Honda, T; Yamaguchi, K

    2000-12-01

    Mannitol lysine crystal violet brilliant green agar (MLCB) is widely used in Japan for Salmonella isolation because the medium has been commercially available. Colonies of Salmonella on MLCB appear colorless with black centers due to H2S gas production; however, most Citrobacter freundii also produce H2S gas. In order to distinguish H2S-positive Salmonella from C. freundii we have improved MLCB. To MLCB was added 1% lactose (L-MLCB). The relation for pH and black center colony formation was examined. The pH of MLCB and L-MLCB inoculated with Salmonella species was slightly acid after 7 h, but the pH of L-MLCB inoculated with C. freundii did not become acid for 24 h. The colony of C. freundii did not have a black center because the production of acid from lactose lowers the pH below 10 where it is needed for H2S to react with iron to produce black pigments. Of 99 Salmonella strains including 13 serotypes tested, all strains had the same colony morphologies on MLCB and L-MLCB. When MLCB and L-MLCB were evaluated with 36 C. freundii strains isolated from foods, only colonies on MLCB had black centers. We conclude that L-MLCB is useful for detection of nonlactose-fermenting, H2S-positive Salmonella in food samples.

  14. Multicenter Evaluation of MRSASelect II Chromogenic Agar for Identification of Methicillin-Resistant Staphylococcus aureus from Wound and Nasal Specimens

    PubMed Central

    Newton, Duane W.; Ledeboer, Nathan A.; Young, Carol; Clark, Andrew E.; Connoly, Jessica; Wolk, Donna M.

    2015-01-01

    Hospitals strive to reduce methicillin-resistant Staphylococcus aureus (MRSA) prevalence via active surveillance of inpatient populations. Rapid and inexpensive screening methods are utilized when molecular methods are not operationally feasible. In this multisite clinical trial, the utility of Bio-Rad's MRSASelect II was evaluated for MRSA identification from remnant nares and wound swabs. The prevalence of MRSA was 11.1% (n = 1,384) from nares samples and 18.1% (n = 842) from wound samples. MRSASelect II had an overall concordance of 95.4% (confidence interval [CI] = 94.5% to 96.2%) compared to a broth-enriched reference standard. Comparisons between results, stratified by examination times, exhibited a nonsignificant trend toward increased positivity at prolonged incubation times. Cefoxitin screening of colonies directly from MRSASelect II was 96.7% (95.8% to 97.3%) concordant compared to testing of colonies following broth enrichment. A comparison of MRSASelect and MRSASelect II revealed no statistical differences; however, the latter exhibited earlier positivity, greater selectivity, and more intense indicator staining, which resulted in facilitated differentiation of positive results. MRSASelect II agar is a simple, rapid, and robust method to routinely screen patients for MRSA colonization without the need for additional testing. PMID:26582836

  15. Comparison of agar dilution and antibiotic gradient strip test with broth microdilution for susceptibility testing of swine Brachyspira species.

    PubMed

    Mirajkar, Nandita S; Gebhart, Connie J

    2016-03-01

    Production-limiting diseases in swine caused by Brachyspira are characterized by mucohemorrhagic diarrhea (B. hyodysenteriae and "B. hampsonii") or mild colitis (B. pilosicoli), while B. murdochii is often isolated from healthy pigs. Emergence of novel pathogenic Brachyspira species and strains with reduced susceptibility to commonly used antimicrobials has reinforced the need for standardized susceptibility testing. Two methods are currently used for Brachyspira susceptibility testing: agar dilution (AD) and broth microdilution (BMD). However, these tests have primarily been used for B. hyodysenteriae and rarely for B. pilosicoli. Information on the use of commercial susceptibility testing products such as antibiotic gradient strips is lacking. Our main objective was to validate and compare the susceptibility results, measured as the minimum inhibitory concentration (MIC), of 6 antimicrobials for 4 Brachyspira species (B. hyodysenteriae, "B. hampsonii", B. pilosicoli, and B. murdochii) by BMD and AD (tiamulin, valnemulin, lincomycin, tylosin, and carbadox) or antibiotic gradient strip (doxycycline) methods. In general, the results of a high percentage of all 4 Brachyspira species differed by ±1 log2 dilution or less by BMD and AD for tiamulin, valnemulin, lincomycin, and tylosin, and by BMD and antibiotic gradient strip for doxycycline. The carbadox MICs obtained by BMD were 1-5 doubling dilutions different than those obtained by AD. BMD for Brachyspira was quicker to perform with less ambiguous interpretation of results when compared with AD and antibiotic gradient strip methods, and the results confirm the utility of BMD in routine diagnostics.

  16. Mitogenomes from type specimens, a genotyping tool for morphologically simple species: ten genomes of agar-producing red algae

    PubMed Central

    Boo, Ga Hun; Hughey, Jeffery R.; Miller, Kathy Ann; Boo, Sung Min

    2016-01-01

    DNA sequences from type specimens provide independent, objective characters that enhance the value of type specimens and permit the correct application of species names to phylogenetic clades and specimens. We provide mitochondrial genomes (mitogenomes) from archival type specimens of ten species in agar-producing red algal genera Gelidium and Pterocladiella. The genomes contain 43–44 genes, ranging in size from 24,910 to 24,970 bp with highly conserved gene synteny. Low Ka/Ks ratios of apocytochrome b and cytochrome oxidase genes support their utility as markers. Phylogenies of mitogenomes and cox1+rbcL sequences clarified classification at the genus and species levels. Three species formerly in Gelidium and Pterocladia are transferred to Pterocladiella: P. media comb. nov., P. musciformis comb. nov., and P. luxurians comb. and stat. nov. Gelidium sinicola is merged with G. coulteri because they share identical cox1 and rbcL sequences. We describe a new species, Gelidium millariana sp. nov., previously identified as G. isabelae from Australia. We demonstrate that mitogenomes from type specimens provide a new tool for typifying species in the Gelidiales and that there is an urgent need for analyzing mitogenomes from type specimens of red algae and other morphologically simple organisms for insight into their nomenclature, taxonomy and evolution. PMID:27739454

  17. The importance of matrix-assisted laser desorption ionization-time of flight mass spectrometry for correct identification of Clostridium difficile isolated from chromID C. difficile chromogenic agar.

    PubMed

    Chen, Jonathan H K; Cheng, Vincent C C; Wong, Oi-Ying; Wong, Sally C Y; So, Simon Y C; Yam, Wing-Cheong; Yuen, Kwok-Yung

    2016-01-11

    The clinical workflow of using chromogenic agar and matrix-assisted laser desorption ionization time-of-fight mass spectrometry (MALDI-TOF MS) for Clostridium difficile identification was evaluated. The addition of MALDI-TOF MS identification after the chromID C. difficile chromogenic agar culture could significantly improve the diagnostic accuracy of C. difficile.

  18. Accumulation of dibenzocyclooctadiene lignans in agar cultures and in stationary and agitated liquid cultures of Schisandra chinensis (Turcz.) Baill.

    PubMed

    Szopa, Agnieszka; Kokotkiewicz, Adam; Marzec-Wróblewska, Urszula; Bucinski, Adam; Luczkiewicz, Maria; Ekiert, Halina

    2016-05-01

    Schisandra chinensis plant in vitro cultures were maintained on Murashige and Skoog (MS) medium supplemented with 3 mg/l 6-benzyladenine (BA) and 1 mg/l 1-naphthaleneacetic acid (NAA) in an agar system and also in two different liquid systems: stationary and agitated. Liquid cultures were grown in batch (30 and 60 days) and fed-batch modes. In the methanolic extracts from lyophilized biomasses and in the media, quantification of fourteen dibenzocyclooctadiene lignans identified based on co-chromatography with authentic standards using high-performance liquid chromatography with diode array detection (HPLC-DAD) and/or liquid chromatography with diode array detection and electrospray ionization mass spectrometry (LC-DAD-ESI-MS) methods. For comparison purposes, phytochemical analyses were performed of lignans in the leaves and fruits of the parent plant. The main lignans detected in the biomass extracts from all the tested systems were schisandrin (max. 65.62 mg/100 g dry weight (DW)), angeloyl-/tigloylgomisin Q (max. 49.73 mg/100 g DW), deoxyschisandrin (max. 43.65 mg/100 g DW), and gomisin A (max. 34.36 mg/100 g DW). The highest total amounts of lignans in the two tested stationary systems were found in extracts from the biomass harvested after 30 days of batch cultivation: 237.86 mg/100 g DW and 274.65 mg/100 g DW, respectively. In the agitated culture, the total content reached a maximum value of 244.80 mg/100 g DW after 60 days of the fed-batch mode of cultivation. The lignans were not detected in the media. This is the first report which documents the potential usefulness of S. chinensis shoot cultures cultivated in liquid systems for practical purposes.

  19. Performance of CHROMagar Selective Medium and Oxacillin Resistance Screening Agar Base for Identifying Staphylococcus aureus and Detecting Methicillin Resistance

    PubMed Central

    Kluytmans, Jan; Van Griethuysen, Arjanne; Willemse, Piet; Van Keulen, Peter

    2002-01-01

    Two new selective media, oxacillin resistance screening agar base (ORSAB) and CHROMagar Staph aureus (CSA), were evaluated for identification of Staphylococcus aureus and for screening of methicillin resistance by addition of antimicrobial agents to these media. A well-defined collection consisting of 1,140 staphylococci was used. A total of 624 were S. aureus, of which 358 were methicillin susceptible and 266 were methicillin resistant, and 516 were coagulase-negative staphylococci. The methicillin-resistant S. aureus (MRSA) strains were selected based on the results of phage typing; 247 different types were included in the analysis. For identification of S. aureus, both media performed better after 24 h than after 48 h. The sensitivities at 24 h were comparable (CSA, 98.6%; ORSAB, 97.1%), but the specificity of CSA was significantly higher (CSA, 97.1%; ORSAB, 92.1%). For screening of methicillin resistance, antibiotic supplements were added to both media. The sensitivity was lower after 24 h (CSA, 58.6%; ORSAB, 84.2%) and increased significantly after 48 h (CSA, 77.5%; ORSAB, 91.4%). At both time intervals ORSAB was significantly more sensitive than CSA. However, the specificities of both media were high after 24 h (CSA, 99.1%; ORSAB, 98.3%) and decreased significantly after 48 h of incubation (CSA, 94.7%; ORSAB, 95.5%). In conclusion, for identification of S. aureus, CSA is more accurate than ORSAB because of a significantly higher specificity. For screening of MRSA, ORSAB performs better than CSA, but the usefulness in clinical practice is limited because a significant number of strains are not detected. PMID:12089266

  20. Diagnostic accuracy assessment of Sensititre and agar disk diffusion for determining antimicrobial resistance profiles of bovine clinical mastitis pathogens.

    PubMed

    Saini, V; Riekerink, R G M Olde; McClure, J T; Barkema, H W

    2011-04-01

    Determining the accuracy and precision of a measuring instrument is pertinent in antimicrobial susceptibility testing. This study was conducted to predict the diagnostic accuracy of the Sensititre MIC mastitis panel (Sensititre) and agar disk diffusion (ADD) method with reference to the manual broth microdilution test method for antimicrobial resistance profiling of Escherichia coli (n = 156), Staphylococcus aureus (n = 154), streptococcal (n = 116), and enterococcal (n = 31) bovine clinical mastitis isolates. The activities of ampicillin, ceftiofur, cephalothin, erythromycin, oxacillin, penicillin, the penicillin-novobiocin combination, pirlimycin, and tetracycline were tested against the isolates. Diagnostic accuracy was determined by estimating the area under the receiver operating characteristic curve; intertest essential and categorical agreements were determined as well. Sensititre and the ADD method demonstrated moderate to highly accurate (71 to 99%) and moderate to perfect (71 to 100%) predictive accuracies for 74 and 76% of the isolate-antimicrobial MIC combinations, respectively. However, the diagnostic accuracy was low for S. aureus-ceftiofur/oxacillin combinations and other streptococcus-ampicillin combinations by either testing method. Essential agreement between Sensititre automatic MIC readings and MIC readings obtained by the broth microdilution test method was 87%. Essential agreement between Sensititre automatic and manual MIC reading methods was 97%. Furthermore, the ADD test method and Sensititre MIC method exhibited 92 and 91% categorical agreement (sensitive, intermediate, resistant) of results, respectively, compared with the reference method. However, both methods demonstrated lower agreement for E. coli-ampicillin/cephalothin combinations than for Gram-positive isolates. In conclusion, the Sensititre and ADD methods had moderate to high diagnostic accuracy and very good essential and categorical agreement for most udder pathogen

  1. VIDAS Salmonella (SLM) assay method EasySLM with ChromID Salmonella (SM2) Agar. Performance Tested Method 020901.

    PubMed

    Johnson, Ronald; Mills, John; Colón-Reveles, Judith

    2009-01-01

    A method modification study was conducted for the VIDAS Salmonella (SLM) assay (AOAC Performance Tested Method 020901) using the EasySLM method to validate a matrix extension for peanut butter. The VIDAS EasySLM method is a simple enrichment procedure compared to traditional Salmonella methods, requiring only pre-enrichment and a single selective enrichment media, Salmonella Xpress 2 (SX2) broth. SX2 replaces the two selective broths in traditional methods and eliminates the M broth transfer, incubation, and subsequent pooling of M broths prior to VIDAS assay. The validation study was conducted under the AOAC Research Institute Emergency Response Validation program. VIDAS SLM was compared to the U.S. Food and Drug Administration's Bacteriological Analytical Manual (FDA-BAM) method for detection of S. enterica ser. Typhimurium in peanut butter. All peanut butter samples were prepared, blind-coded, and shipped to the method developers' laboratory by Q Laboratories. In addition, Q Laboratories performed most probable number and reference method analyses on peanut butter samples. The VIDAS EasySLM ChromID Salmonella (SM2) Agar was previously validated in the Performance Tested Methods program for the detection of Salmonella in roast beef, raw ground pork, turkey, pork sausage, raw chicken breast, dry pet food, whole milk, ice cream, bagged spinach, shrimp (raw, peeled), raw cod, spent irrigation water, pecans, peanut butter, dry pasta, cake mix, ground black pepper, nonfat dry milk, liquid eggs, cantaloupe, and orange juice. In the matrix extension study for peanut butter, the VIDAS EasySLM method was shown to be equivalent to the appropriate reference culture procedure using both buffered peptone water pre-enrichment and the FDA-BAM lactose pre-enrichment in the two-step enrichment method with SX2 media. The current study extends the validation to include peanut butter.

  2. Coculture of spermatogonia with somatic cells in a novel three-dimensional soft-agar-culture-system.

    PubMed

    Stukenborg, Jan-Bernd; Wistuba, Joachim; Luetjens, C Marc; Elhija, Mahmoud Abu; Huleihel, Mahmoud; Lunenfeld, Eitan; Gromoll, Jörg; Nieschlag, Eberhard; Schlatt, Stefan

    2008-01-01

    Isolation and culture of spermatogonial stem cells (SSCs) has become an approach to study the milieu and the factors controlling their expansion and differentiation. Traditional conventional cell culture does not mimic the complex situation in the seminiferous epithelium providing a basal, intraepithelial, and adluminal compartment to the developing male germ cells. SSCs are located in specific stem cell niches whose features and functional parameters are thus far poorly understood. It was the aim of this study to isolate SSCs and to explore their expansion and differentiation potential in a novel three-dimensional Soft-Agar-Culture-System (SACS). This system provides three-dimensional structural support and multiple options for manipulations through the addition of factors, cells, or other changes. The system has revolutionized research on blood stem cells by providing a tool for clonal analysis of expanding and differentiating blood cell lineages. In our studies, SSCs are enriched using Gfralpha-1 as a specific surface marker and magnetic-activated cell sorting as a separation approach. At termination of the culture, we determined the type and number of germ cells obtained after the first 24 hours of culture. We also determined cell types and numbers in expanding cell clones of differentiating germ cells during the subsequent 15 days of culture. We analyzed a supportive effect of somatic cell lineages added to the solid part of the culture system. We conclude that our enrichment and culture approach is highly useful for exploration of SSC expansion and have found indications that the system supports differentiation up to the level of postmeiotic germ cells.

  3. Assessment of the suitability of mannitol salt agar for growing bovine-associated coagulase-negative staphylococci and its use under field conditions.

    PubMed

    De Visscher, A; Haesebrouck, F; Piepers, S; Vanderhaeghen, W; Supré, K; Leroy, F; Van Coillie, E; De Vliegher, S

    2013-10-01

    This study aimed at testing the applicability of mannitol salt agar (MSA), a medium generally used in human medicine for differentiating Staphylococcus aureus from coagulase-negative staphylococci (CNS), for culturing bovine-associated CNS species. All test isolates from a comprehensive collection of well-identified CNS species, including both reference strains and field isolates, were able to grow. Subsequently, bulk milk samples and teat apex swabs were used to examine the capability of MSA for yielding CNS under field conditions. Sixty-nine and 47 phenotypically different colonies were retrieved from bulk milk and teat apices, respectively. The majority of isolates from teat apices were staphylococci, whereas in bulk milk, staphylococci formed a minority. After 24h of growth, recovery of separate colonies of CNS was much more convenient on MSA compared to a non-selective blood agar. The results of this study indicate that MSA is a suitable medium for both growth and recovery of bovine-associated CNS.

  4. [Detection of TDH-producing Vibrio parahaemolyticus O3:K6 from naturally contaminated shellfish using an immunomagnetic separation method and chromogenic agar medium].

    PubMed

    Hara-Kudo, Y; Sugiyama, K; Nishina, T; Saitoh, A; Nakagawa, H; Ichihara, T; Konuma, H; Hasegawa, J; Kumagai, S

    2001-11-01

    We attempted to isolate TDH-producing Vibrio parahaemolyticus O3:K6 from shellfish. Asari samples were incubated with TSB supplemented with 2% (w/v) NaCl for 6 h, and then the 6-h cultures were incubated with salt polymyxin broth for 18 h. After the two-step enrichment, a 1 ml portion of the culture was treated with magnetic beads coated with K6 antibody for immunoconcentration of V. parahaemolyticus O3:K6. The immunoconcentrated and untreated cultures were plated onto a chromogenic agar and TCBS agar media for isolation of V. parahaemolyticus. TDH-producing V. parahaemolyticus O3:K6 was isolated from 3 out of 66 lots (4.5%) of naturally contaminated Asari. Six of 4,265 colonies suspected as V. parahaemolyticus (0.14%) were TDH-producing V. parahaemolyticus O3:K6.

  5. Preparation of nanocellulose from micro-crystalline cellulose: The effect on the performance and properties of agar-based composite films.

    PubMed

    Shankar, Shiv; Rhim, Jong-Whan

    2016-01-01

    A facile approach has been performed to prepare nanocellulose (NC) from micro-crystalline cellulose (MCC) and test their effect on the performance properties of agar-based composite films. The NC was characterized by STEM, XRD, FTIR, and TGA. The NC was well dispersed in distilled water after sonication and their size was in the range of 100-500nm. The XRD results revealed the crystallinity of NC. The crystallinity index of NC (0.71) was decreased compared to the MCC (0.81). The effect of NC or MCC content (1, 3, 5 and 10wt% based on agar) on the mechanical, water vapor permeability (WVP), and thermal properties of the composites were studied. The NC obtained from MCC can be used as a reinforcing agent for the preparation of biodegradable composites films for their potential use in the development of biodegradable food packaging materials.

  6. Effects of Agar Gel Strength and Fat on Oral Breakdown, Volatile Release, and Sensory Perception Using in Vivo and in Vitro Systems.

    PubMed

    Frank, Damian; Eyres, Graham T; Piyasiri, Udayasika; Cochet-Broch, Maeva; Delahunty, Conor M; Lundin, Leif; Appelqvist, Ingrid M

    2015-10-21

    The density and composition of a food matrix affect the rates of oral breakdown and in-mouth flavor release as well as the overall sensory experience. Agar gels of increasing concentration (1.0, 1.7, 2.9, and 5% agarose) with and without added fat (0, 2, 5, and 10%) were spiked with seven aroma volatiles. Differences in oral processing and sensory perception were systematically measured by a trained panel using a discrete interval time intensity method. Volatile release was measured in vivo and in vitro by proton transfer reaction mass spectrometry. Greater oral processing was required as agar gel strength increased, and the intensity of flavor-related sensory attributes decreased. Volatile release was inversely related to gel strength, showing that physicochemical phenomena were the main mechanisms underlying the perceived sensory changes. Fat addition reduced the amount of oral processing and had differential effects on release, depending on the fat solubility or lipophilicity of the volatiles.

  7. Antimicrobial susceptibility testing for Helicobacter pylori isolates from Brazilian children and adolescents: comparing agar dilution, E-test, and disk diffusion.

    PubMed

    Ogata, Silvio Kazuo; Gales, Ana Cristina; Kawakami, Elisabete

    2014-01-01

    Antimicrobial susceptibility testing for Helicobacter pylori is increasingly important due to resistance to the most used antimicrobials agents. Only agar dilution method is approved by CLSI, but it is difficult to perform routinely. We evaluated the reliability of E-test and disk diffusion comparing to agar dilution method on Helicobacter pylori antimicrobial susceptibility testing. Susceptibility testing was performed for amoxicillin, clarithromycin, furazolidone, metronidazole and tetracycline using E-test, disk-diffusion and agar dilution method in 77 consecutive Helicobacter pylori strains from dyspeptic children and adolescents. Resistance rates were: amoxicillin - 10.4%, 9% and 68.8%; clarithromycin - 19.5%, 20.8%, 36.3%; metronidazole - 40.2%33.7%, 38.9%, respectively by agar dilution, E-test and disk diffusion method. Furazolidone and tetracycline showed no resistance rates. Metronidazole presented strong correlation to E-test (r = 0.7992, p < 0.0001) and disk diffusion method (r=-0.6962, p < 0.0001). Clarithromycin presented moderate correlation to E-test (r = 0.6369, p < 0.0001) and disk diffusion method (r=-0.5656, p < 0.0001). Amoxicillin presented weak correlation to E-test (r = 0.3565, p = 0.0015) and disk diffusion (r=-0.3565, p = 0.0015). Tetracycline presented weak correlation with E-test (r = 0.2346, p = 0.04) and furazolidone to disk diffusion (r=-0.0288, p = 0.8038). E-test presented better agreement with gold standard. It is an easy and reliable method for Helicobacter pylori susceptibility testing. Disk diffusion method presented high disagreement and high rates of major errors.

  8. Comparison of the Copan eSwab System with an Agar Swab Transport System for Maintenance of Fastidious Anaerobic Bacterium Viability

    PubMed Central

    Citron, Diane M.; Leoncio, Eliza S.; Goldstein, Ellie J. C.

    2016-01-01

    We compared the eSwab system to a swab with an anaerobic transport semisolid agar system for their capacities to maintain the viability of 20 species of fastidious anaerobes inoculated on the bench and held at ambient or refrigerator temperature for 24 or 48 h. On average, both systems maintained similar viabilities among analogous groups of organisms at both temperatures, although there were quantitative differences among some species. PMID:26888906

  9. Abilities of the mCP Agar method and CRENAME alpha toxin-specific real-time PCR assay to detect Clostridium perfringens spores in drinking water.

    PubMed

    Maheux, Andrée F; Bérubé, Eve; Boudreau, Dominique K; Villéger, Romain; Cantin, Philippe; Boissinot, Maurice; Bissonnette, Luc; Bergeron, Michel G

    2013-12-01

    We first determined the analytical specificity and ubiquity (i.e., the ability to detect all or most strains) of a Clostridium perfringens-specific real-time PCR (rtPCR) assay based on the cpa gene (cpa rtPCR) by using a bacterial strain panel composed of C. perfringens and non-C. perfringens Clostridium strains. All non-C. perfringens Clostridium strains tested negative, whereas all C. perfringens strains tested positive with the cpa rtPCR, for an analytical specificity and ubiquity of 100%. The cpa rtPCR assay was then used to confirm the identity of 116 putative C. perfringens isolates recovered after filtration of water samples and culture on mCP agar. Colonies presenting discordant results between the phenotype on mCP agar and cpa rtPCR were identified by sequencing the 16S rRNA and cpa genes. Four mCP(-)/rtPCR(+) colonies were identified as C. perfringens, whereas 3 mCP(+)/rtPCR(-) colonies were identified as non-C. perfringens. The cpa rtPCR was negative with all 51 non-C. perfringens strains and positive with 64 of 65 C. perfringens strains. Finally, we compared mCP agar and a CRENAME (concentration and recovery of microbial particles, extraction of nucleic acids, and molecular enrichment) procedure plus cpa rtPCR (CRENAME + cpa rtPCR) for their abilities to detect C. perfringens spores in drinking water. CRENAME + cpa rtPCR detected as few as one C. perfringens CFU per 100 ml of drinking water sample in less than 5 h, whereas mCP agar took at least 25 h to deliver results. CRENAME + cpa rtPCR also allows the simultaneous and sensitive detection of Escherichia coli and C. perfringens from the same potable water sample. In itself, it could be used to assess the public health risk posed by drinking water potentially contaminated with pathogens more resistant to disinfection.

  10. Gelatin-agar lumbosacral spine phantom: a simple model for learning the basic skills required to perform real-time sonographically guided central neuraxial blocks.

    PubMed

    Li, Jia Wei; Karmakar, Manoj K; Li, Xiang; Kwok, Wing Hong; Ngan Kee, Warwick Dean

    2011-02-01

    This report describes the preparation of a gelatin-agar spine phantom that was used for spinal sonography and to practice the hand-eye coordination skills required to perform sonographically guided central neuraxial blocks. The phantom was prepared by embedding a lumbosacral spine model into a mixture of gelatin and agar in a plastic box. Cellulose powder and chlorhexidine were also added to the mixture, after which it was allowed to solidify. Sonography of the osseous elements of the lumbosacral spine in the phantom was then performed, and their sonographic appearances were compared to those in volunteers. Simulated real-time sonographically guided paramedian spinal needle insertions were also performed in the phantom. The texture and echogenicity of the phantom were subjectively comparable to those of tissue in vivo. The osseous elements of the spine in the phantom were clearly delineated, and their sonographic appearances were comparable to those seen in vivo in the volunteers. During the simulated sonographically guided spinal injections, the needle could be clearly visualized, but the phantom provided little tactile feedback. In conclusion, the gelatin-agar spine phantom is a simple and inexpensive sonographic spine model that has a tissuelike texture and echogenicity. It can be used to study the osseous anatomy of the lumbar spine and practice the skills required to perform sonographically guided central neuraxial blocks.

  11. A modified MacConkey agar for selective enumeration of necrotoxigenic E. coli O55 and probiotic E. coli Nissle 1917.

    PubMed

    Splichalova, Alla; Splichal, Igor; Sonnenborn, Ulrich; Rada, Vojtech

    2014-09-01

    An agar selective enumeration of necrotoxigenic Escherichia coli O55 (NTEC2) and probiotic E. coli Nissle 1917, using modified MacConkey agar, was developed to study bacterial interference between these E. coli strains in a gnotobiotic piglet model. Replacement of lactose with saccharose in the agar enables the direct visual enumeration of red colonies of E. coli O55 and yellow colonies of E. coli Nissle 1917 that are co-cultured in the same Petri dish. A total of 336 colonies (168 for each color) were subjected to strain-specific PCR identification with LNA probes. Sensitivity, specificity, and positive and negative predictive values were 96.43%, 95.83%, 95.86% and 96.41% respectively in E. coli O55, and 98.21%, 97.02%, 97.06% and 98.19% respectively in E. coli Nissle 1917. Color-based enumeration of both E. coli strains in colonic contents and mesenteric lymph nodes homogenates of gnotobiotic piglets demonstrated the applicability of this method for the gnotobiotic piglet model of enteric diseases.

  12. Comparison of agar-based methods for the isolation and enumeration of heterotrophic bacteria with the new multidose IDEXX SimPlate method.

    PubMed

    Vulindlu, M; Charlett, A; Surman, S; Lee, J V

    2004-01-01

    Pour and spread plates are the conventional methods of choice for the isolation and enumeration of heterotrophic microorganisms in treated water supplies. The tests are performed at 22 degrees C and 37 degrees C for 72 h and 48 h respectively. Counts at 22 degrees C are associated with pollution of water systems from external sources, while counts at 37 degrees C are used as an indication of treatment plant performance and the deterioration of the general quality of water. Conventional methods using Yeast Extract Agar for a pour plate and R2A agar for a spread plate were compared with the multidose IDEXX SimPlate method for the isolation and enumeration of heterotrophic bacteria in water. SimPlate gave a significantly higher count on average than the conventional methods. The R2A method showed the next highest count, being significantly higher than Yeast Extract Agar. In addition, unlike the pour and spread plate methods, SimPlate was easier to use, reduced labour, and the test results were far easier to read.

  13. Evaluation of the ANSR for Salmonella assay for identification of Salmonella spp. from colony picks from selective/differential agar media: first action 2013.14.

    PubMed

    Mozola, Mark; Botimer, Maximilian; Jagadics, Carolyn; Norton, Paul; Caballero, Oscar; Enslin, Nicole; Biswas, Preetha; Rice, Jennifer

    2014-01-01

    A collaborative study was conducted to evaluate performance of the ANSR for Salmonella assay for identification of Salmonella spp. from colony picks taken from selective/differential agar media. The ANSR Salmonella assay is an isothermal nucleic acid amplification test based on the nicking enzyme amplification reaction chemistry. The test can be completed in less than 40 min including sample preparation. A total of 18 laboratories representing industry, government, academic, and commercial testing laboratories participated in the study. Each collaborator tested up to 84 samples, comprised of colony picks of six Salmonella spp. and six non-salmonellae taken from six selective/differential agar media as well as tryptic soy agar. A total of 1441 analyses were performed, 1416 of which gave the correct identification, for overall accuracy of 98.3%. For identification of Salmonella spp., 755 of 756 tests (99.9%) produced the correct result. For identification of non-salmonellae as such, 661 of 685 assays (96.5%) produced the correct result. Of the 18 laboratories, 15 produced data sets with 99-100% accuracy. The majority of false-positive results were clustered in three laboratories; analysis of raw data suggests procedural difficulties in at least two cases, which may explain the atypical data from these collaborators. The ANSR Salmonella assay can be used as a rapid, accurate adjunct or alternative to biochemical testing for identification of presumptive Salmonella spp. isolates.

  14. Aerococcus urinae and trimethoprim-sulfamethoxazole.

    PubMed

    Humphries, Romney M; Lee, Courtney; Hindler, Janet A

    2011-11-01

    Aerococcus urinae has been described as resistant to trimethoprim-sulfamethoxazole (SXT), but the test medium may affect this observation. Twenty-seven clinical isolates of A. urinae tested susceptible to SXT in cation-adjusted Mueller-Hinton broth (CAMHB) plus lysed horse blood and resistant in CAMHB plus lysed sheep blood.

  15. Aerococcus urinae and Trimethoprim-Sulfamethoxazole ▿

    PubMed Central

    Humphries, Romney M.; Lee, Courtney; Hindler, Janet A.

    2011-01-01

    Aerococcus urinae has been described as resistant to trimethoprim-sulfamethoxazole (SXT), but the test medium may affect this observation. Twenty-seven clinical isolates of A. urinae tested susceptible to SXT in cation-adjusted Mueller-Hinton broth (CAMHB) plus lysed horse blood and resistant in CAMHB plus lysed sheep blood. PMID:21918023

  16. Extended-Spectrum beta (β)-Lactamases and Antibiogram in Enterobacteriaceae from Clinical and Drinking Water Sources from Bahir Dar City, Ethiopia

    PubMed Central

    Abera, Bayeh; Kibret, Mulugeta; Mulu, Wondemagegn

    2016-01-01

    Background The spread of Extended-Spectrum beta (β)-Lactamases (ESBL)-producing Enterobacteriaceae has become a serious global problem. ESBL-producing Enterobacteriaceae vary based on differences in antibiotic use, nature of patients and hospital settings. This study was aimed at determining ESBL and antibiogram in Enterobacteriaceae isolates from clinical and drinking water sources in Bahir Dar City, Northwest Ethiopia. Methods Enterobacteriaceae species were isolated from clinical materials and tap water using standard culturing procedures from September 2013 to March 2015. ESBL-producing-Enterobacteriaceae were detected using double-disk method by E-test Cefotaxim/cefotaxim+ clavulanic acid and Ceftazidime/ceftazidime+ clavulanic acid (BioMerieux SA, France) on Mueller Hinton agar (Oxoid, UK). Results Overall, 274 Enterobacteriaceae were isolated. Of these, 210 (44%) were from patients and 64 (17.1%) were from drinking water. The median age of the patients was 28 years. Urinary tract infection and blood stream infection accounted for 60% and 21.9% of Enterobacteriaceae isolates, respectively. Klebsiella pneumoniae was isolated from 9 (75%) of neonatal sepsis. The overall prevalence of ESBL-producing Enterobacteriaceae in clinical and drinking water samples were 57.6% and 9.4%, respectively. The predominant ESBL-producers were K. pneumoniae 34 (69.4%) and Escherichia coli 71 (58.2%). Statistically significant associations were noted between ESBL-producing and non- producing Enterobacteriaceae with regard to age of patients, infected body sites and patient settings (P = 0.001). ESBL-producing Enterobacteriaceae showed higher levels of resistance against chloramphenicol, ciprofloxacin and cotrimoxazole than non-ESBL producers (P = 0.001) Conclusions ESBL-producing Enterobacteriaceae coupled with high levels of other antimicrobials become a major concern for treatment of patients with invasive infections such as blood stream infections, neonatal sepsis and urinary

  17. OXA-23 and ISAba1-OXA-66 class D β-lactamases in Acinetobacter baumannii isolates from companion animals.

    PubMed

    Ewers, Christa; Klotz, Peter; Leidner, Ursula; Stamm, Ivonne; Prenger-Berninghoff, Ellen; Göttig, Stephan; Semmler, Torsten; Scheufen, Sandra

    2017-01-01

    Acinetobacter baumannii is recognised as a major pathogen of nosocomial infections that frequently show resistance to last-resort antimicrobials. To investigate whether A. baumannii from companion animals harbour carbapenem resistance mechanisms, 223 clinical isolates obtained from veterinary clinics between 2000 and 2013 in Germany were screened for carbapenem-non-susceptibility employing meropenem-containing Mueller-Hinton agar plates. Minimum inhibitory concentration (MIC) data were obtained using the VITEK(®)2 system. Assignment to international clones (ICs) was done by multiplex PCR or repetitive sequence-based PCR employing the DiversiLab system. Clonality was studied using pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST). Genes encoding carbapenemases and aminoglycoside-modifying enzymes were detected by PCR. In three samples from dogs, carbapenem-resistant A. baumannii carrying the blaOXA-23 gene on plasmids and located on transposon Tn2008 were identified. The isolates belonged to sequence type ST1(P) (clonal complex CC1/IC1/pulsotype II) and ST10(P) (CC10/IC8/pulsotype IV) according to the Pasteur MLST scheme, and to ST231(Ox) (CC109) and ST585(Ox) (CC447) following the Oxford scheme. Insertion sequence ISAba1 was identified upstream of blaOXA-66 in 58 A. baumannii isolates. MLST referred them to ST2(P) (CC2/IC2/pulsotypes I and III), ST208(Ox), ST350(Ox) and ST556(Ox) (all CC118), respectively. PFGE suggested nosocomial spread of these highly related strains, which frequently demonstrated a multidrug-resistant phenotype, in one veterinary clinic. These data show that A. baumannii from companion animals reveal resistance determinants and clonal lineages of strains globally emerging in humans. This suggests an interspecies transmission and warrants molecular surveillance of A. baumannii in veterinary clinics to mitigate its further spread.

  18. First characterization of a Providencia stuartii clinical isolate from a Tunisian intensive care unit coproducing VEB-1-a, OXA-2, qnrA6 and aac(6')-Ib-cr determinants.

    PubMed

    Mahrouki, Sihem; Chihi, Hela; Bourouis, Amel; Ben Moussa, Mohamed; Belhadj, Omrane

    2014-01-01

    A clinical Providencia stuartii isolate SM662 was recovered from a patient hospitalized in the intensive care unit at the Military hospital, Tunisia. This isolate was resistant to penicillins, cephalosporins, aminoglycosides and fluoroquinolones. A marked in vitro synergy between ceftazidime or cefotaxime and amoxicillin-clavulanic acid on Mueller-Hinton agar plates suggested the presence of an extended-spectrum-β-lactamase. In addition, an unusual synergy was found between cefepime or aztreonam, and cefoxitin or imipenem on a double disk synergy test suggesting a VEB-type extended-spectrum-β-lactamase. The characterization of β-lactamases and associated resistance genes was performed by isoelectric focusing, polymerase chain reaction and nucleotide sequencing. Two β-lactamases bands with pI values of 5.4 and 7.7, which were matched to TEM-1, VEB-1-a and OXA-2-like β-lactamases were detected. The blaVEB-1-a gene was found to be associated with complex genetic structures, including Re elements. These β-lactamases were not transferred by electroporation or conjugation experiments to the transconjugants and electroporants. Hybridization methods showed that the extended-spectrum-β-lactamase encoding gene may have a chromosomal localization. The isolate SM662 produced the quinolone resistance determinants qnrA6 and aac(6')-Ib-cr which were successfully transferred. The detection of an associated chromosomal quinolone resistance revealed the presence of a gyrA mutation at codon 83 (Ser83Ile). This is the first report of the linkage VEB-1-a/OXA-2-like in P. stuartii associated with the description of qnrA6 and aac(6')-Ib-cr genes in this isolate.

  19. Environmental Methicillin-Resistant Staphylococcus aureus in a Veterinary Teaching Hospital During a Nonoutbreak Period

    PubMed Central

    Johnson, Amanda; Nava-Hoet, Rocio C.; Bateman, Shane; Hillier, Andrew; Dyce, John; Gebreyes, Wondwossen A.; Wittum, Thomas E.

    2011-01-01

    Abstract Concurrent to reports of zoonotic and nosocomial transmission of methicillin-resistant Staphylococcus aureus (MRSA) in veterinary settings, recent evidence indicates that the environment in veterinary hospitals may be a potential source of MRSA. The present report is a cross-sectional study to determine the prevalence of MRSA on specific human and animal contact surfaces at a large veterinary hospital during a nonoutbreak period. A total of 156 samples were collected using Swiffers® or premoistened swabs from the small animal, equine, and food animal sections. MRSA was isolated and identified by pre-enrichment culture and standard microbiology procedures, including growth on Mueller-Hinton agar supplemented with NaCl and oxacillin, and by detection of the mecA gene. Staphylococcal chromosome cassette mec (SCCmec) typing and pulsed-field gel electrophoresis profile were also determined. MRSA was detected in 12% (19/157) of the hospital environments sampled. The prevalence of MRSA in the small animal, equine, and food animal areas were 16%, 4%, and 0%, respectively. Sixteen of the MRSA isolates from the small animal section were classified as USA100, SCCmec type II, two of which had pulsed-field gel electrophoresis pattern that does not conform to any known type. The one isolate obtained from the equine section was classified as USA500, SCCmec type IV. The molecular epidemiological analysis revealed a very diverse population of MRSA isolates circulating in the hospital; however, in some instances, multiple locations/surfaces, not directly associated, had the same MRSA clone. No significant difference was observed between animal and human contact surfaces in regard to prevalence and type of isolates. Surfaces touched by multiple people (doors) and patients (carts) were frequently contaminated with MRSA. The results from this study indicate that MRSA is present in the environment even during nonoutbreak periods. This study also identified specific surfaces in

  20. Silver resistance in MRSA isolated from wound and nasal sources in humans and animals.

    PubMed

    Loh, Jia V; Percival, Steven L; Woods, Emma J; Williams, Nicola J; Cochrane, Christine A

    2009-02-01

    Methicillin-resistant Staphylococcus aureus (MRSA) colonises skin, nasal passages and dermal wounds. Methods used to manage wounds infected and colonised with MRSA often include the use of topical antiseptics such as ionic silver and iodine. The objectives of this study were to determine the prevalence of silver-resistance (sil) genes in MRSA and methicillin-resistant coagulase-negative staphylococci (MR-CNS) isolated from wounds and nasal cavities of humans and animals, and also to determine the susceptibility of sil-positive and sil-negative MRSA isolates to a silver-containing Hydrofiber (SCH) wound dressing, on planktonic silE-positive and silE-negative MRSA. Polymerase chain reaction was used to determine the presence of three silver-resistance (sil) genes, silE, silP and silS in 33 MRSA and 8 methicillin-resistant staphylococci (MR-CNS). SilP and silS genes were absent in all isolates tested; however, two MRSA strains were found to contain the silE gene, together with one isolate of MR-CNS. Phenotypic resistance of the silE-positive strains and their susceptibility to the SCH dressing was evaluated using the zone of inhibition test on Mueller Hinton agar, and confocal laser microscopy using a live/dead fluorescent stain. Results confirmed that the SCH dressing was effective in killing all MRSA strains with and without the silE gene. First, this study showed that the prevalence of sil genes was low in the isolates investigated; and secondly, that the presence of a silver-resistance gene (silE) in MRSA and MR-CNS did not afford protection to the organism in the presence of a SCH wound dressing. The use of topical antiseptics in chronic wound care should be considered before the use of antibiotics that can result in their overuse and the risk of further resistance.

  1. In vitro Comparison of Generic and Branded Preparations of Amoxicillin with Potassium Clavulanate

    PubMed Central

    Dawane, Jayshree

    2016-01-01

    Introduction The Medical Council of India (MCI) has guidelines for physicians to prescribe drugs with generic names. But physicians and patients might have prejudices against generic drug substitution or concerns regarding quality and generics effectiveness. If the drugs are ineffective, they can result in adverse clinical outcomes such as treatment failure. According to WHO, β-lactams are the most common substandard drugs to be produced amongst antibiotics. Aim To evaluate and compare invitro efficacy of generic and branded preparations of Amoxicillin with Potassium Clavulanate. Materials and Methods One generic (C) and 5 branded formulations (A,B,D,E,F) of amoxicillin with potassium clavulanate were taken for microbiological assay. Coding was done. Sterile disks were instilled with 10μl of preparations and disk diffusion was screened by Kirby Bauer Method using Mueller Hinton Agar. Bacterial Strains used were Staphylococcus aureus (S. aureus) and Escherichia Coli. Zone of inhibition was measured. Statistical Analysis was done using repeated measures one-way ANOVA followed by Tukey’s test. Results Disk Diffusion test showed that branded Drug F has statistically significant less zone of inhibition (p < 0.001) for S. Aureus and (p < 0.05) for E.coli in comparison with generic drug C. Zone of inhibition of branded Drug A, B & E was comparable with the generic drug C. Conclusion The results of this study indicate that the generic drug tested was equally effective compared to the tested branded drugs except branded Drug D and F. This suggests that efficacy of generic drug is equivalent to branded drugs and maybe used interchangeably with branded drugs. PMID:27790457

  2. Evaluation of the Antibacterial Activity of Green Propolis Extract and Meadowsweet Extract Against Staphylococcus aureus Bacteria: Importance in Would Care Compounding Preparations.

    PubMed

    Lupatini, Nogueira Rodrigo José; Danopoulos, Panagiota; Swikidisa, Rosita; Alves, Pinheiro Vanessa

    2016-01-01

    The use of natural products in compounded wound care formulas is an exciting avenue to pursue for compounding pharmacists since these natural products may contain compounds that promote healing on their own. The use of these natural extracts as an alternative therapy for wound care may also provide several benefits, such as decreased inflammation, infection, side effects, and treatment costs. Thus far, several studies have demonstrated antimicrobial activity for various natural product extracts, including green propolis and meadowsweet. The antimicrobial properties of these extracts make them particularly interesting for wound care because the healing process is significantly delayed by bacterial infection and colonization at the site of injury. Therefore, to further investigate the antimicrobial properties of green propolis and meadowsweet extracts, we performed minimum inhibitory concentration and minimum bactericidal concentration assays against Staphylococcus aureus, a microorganism known to cause wound infections. The antimicrobial activity of green propolis and meadowsweet extracts was tested in vitro against a standard strain of Staphylococcus aureus in brain heart infusion broth and Mueller-Hinton agar plates. Green propolis extract demonstrated antimicrobial activity against Staphylococcus aureus with a minimum inhibitory concentration of 1.25 mg/mL and a minimum bactericidal concentration of 1.25 mg/mL. In contrast, meadowsweet extract failed to inhibit Staphylococcus aureus growth at the highest concentration tested (30 mg/mL). Green propolis was more effective than meadowsweet extract at inhibiting the growth of Staphylococcus aureus, suggesting that the addition of green propolis extract in wound care formulas might be more beneficial for the treatment of wounds. Therefore, we propose that green propolis extract is a promising natural product for wound care formulations.

  3. Standardization of Operator-Dependent Variables Affecting Precision and Accuracy of the Disk Diffusion Method for Antibiotic Susceptibility Testing

    PubMed Central

    Maurer, Florian P.; Pfiffner, Tamara; Böttger, Erik C.; Furrer, Reinhard

    2015-01-01

    Parameters like zone reading, inoculum density, and plate streaking influence the precision and accuracy of disk diffusion antibiotic susceptibility testing (AST). While improved reading precision has been demonstrated using automated imaging systems, standardization of the inoculum and of plate streaking have not been systematically investigated yet. This study analyzed whether photometrically controlled inoculum preparation and/or automated inoculation could further improve the standardization of disk diffusion. Suspensions of Escherichia coli ATCC 25922 and Staphylococcus aureus ATCC 29213 of 0.5 McFarland standard were prepared by 10 operators using both visual comparison to turbidity standards and a Densichek photometer (bioMérieux), and the resulting CFU counts were determined. Furthermore, eight experienced operators each inoculated 10 Mueller-Hinton agar plates using a single 0.5 McFarland standard bacterial suspension of E. coli ATCC 25922 using regular cotton swabs, dry flocked swabs (Copan, Brescia, Italy), or an automated streaking device (BD-Kiestra, Drachten, Netherlands). The mean CFU counts obtained from 0.5 McFarland standard E. coli ATCC 25922 suspensions were significantly different for suspensions prepared by eye and by Densichek (P < 0.001). Preparation by eye resulted in counts that were closer to the CLSI/EUCAST target of 108 CFU/ml than those resulting from Densichek preparation. No significant differences in the standard deviations of the CFU counts were observed. The interoperator differences in standard deviations when dry flocked swabs were used decreased significantly compared to the differences when regular cotton swabs were used, whereas the mean of the standard deviations of all operators together was not significantly altered. In contrast, automated streaking significantly reduced both interoperator differences, i.e., the individual standard deviations, compared to the standard deviations for the manual method, and the mean of the

  4. Antifungal susceptibility and virulence factors of clinically isolated dermatophytes in Tehran, Iran

    PubMed Central

    Afshari, Mohammad Ali; Shams-Ghahfarokhi, Masoomeh; Razzaghi-Abyaneh, Mehdi

    2016-01-01

    Background and Objectives: Dermatophytes possess a wide array of virulence factors and various antifungal susceptibility patterns which influence their pathogenesis in humans and animals. The aim of this study was to evaluate antifungal susceptibility and keratinase and proteinase activity of 49 dermatophyte strains from the genera Microsporum, Trichophyton and Epidermophyton which were isolated from human cases of dermatophytosis. Materials and Methods: Forty-nine dermatophyte strains isolated from clinical samples were cultured on general and specific culture media. Keratinase and proteinase activity was screened on solid mineral media and confirmed in liquid cultures. Drug susceptibility toward azoles (fluconazole, ketoconazole and itraconazole), griseofulvin and terbinafine was evaluated using disk diffusion method on Mueller-Hinton agar and minimum inhibitory concentrations (MICs) were determined using microbroth dilution assay according to the Clinical and Laboratory Standards Institute (CLSI) guidelines. Results: Our results indicated that clinically isolated dermatophytes from 7 major species produced keratinase and proteinase at different extents. The mean keratinase and proteinase activity was reported as 6.69 ± 0.31 (U/ml) and 2.10 ± 0.22 (U/ml) respectively. Disk diffusion and microbroth dilution (MIC) results of antifungal susceptibility testing showed that ketoconazole was the most effective drug against Epidermophyton floccosum and Trichophyton mentagrophytes, itraconazole against T. rubrum and E. floccosum, and griseofulvin and terbinafine against Trichophyton verrucosum. Our results showed that all dermatophyte isolates were resistant to fluconazole. Overall, ketoconazole and itraconazole were the most effective drugs for all dermatophyte species tested. Conclusion: Our results showed that antifungal susceptibility testing is an urgent need to select drugs of choice for treatment of different types of dermatophytosis and further indicated the

  5. Rates of gastrointestinal tract colonization of carbapenem-resistant Enterobacteriaceae and Pseudomonas aeruginosa in hospitals in Saudi Arabia

    PubMed Central

    Abdalhamid, B.; Elhadi, N.; Alabdulqader, N.; Alsamman, K.; Aljindan, R.

    2016-01-01

    Carbapenem-resistant Enterobacteriaceae (CRE) and carbapenem-resistant Pseudomonas aeruginosa (CRPAE) are globally a major medical issue, especially in intensive care units. The digestive tract is the main reservoir for these isolates; therefore, rectal swab surveillance is highly recommended. The purpose of this study was to detect the prevalence of gastrointestinal tract colonization of CRE and CRPAE in patients admitted to intensive care units in Saudi Arabia. This project also aimed to characterize carbapenem-hydrolyzing enzyme production in these isolates. From February to May 2015, 200 rectal swab specimens were screened by CHROMagar KPC. Organism identification and susceptibility testing were performed using the Vitek 2 system. One CRE and 13 CRPAE strains were identified, for a prevalence of 0.5% (1/200) and 6.5% (13/200) respectively. Strains showed high genetic diversity using enterobacterial repetitive intergenic consensus sequence-based PCR. NDM type and VIM type were detected by PCR in four and one CRPAE isolates respectively. ampC overexpression was detected in eight CRPAE isolates using Mueller-Hinton agar containing 1000 μg/mL cloxacillin. CTX-M-15 type was detected in 1 CRE by PCR. The prevalence of CRE strain colonization was lower than that of CRPAE isolates. The detection of NDM and VIM in the colonizing CRPAE strains is a major infection control concern. To our knowledge, this is the first study in Saudi Arabia and the gulf region focusing on digestive tract colonization of CRE and CRPAE organisms and characterizing the mechanisms of carbapenem resistance. PMID:26933499

  6. Evaluation of an Automated System for Reading and Interpreting Disk Diffusion Antimicrobial Susceptibility Testing of Fastidious Bacteria

    PubMed Central

    Idelevich, Evgeny A.; Becker, Karsten; Schmitz, Janne; Knaack, Dennis; Peters, Georg; Köck, Robin

    2016-01-01

    Results of disk diffusion antimicrobial susceptibility testing depend on individual visual reading of inhibition zone diameters. Therefore, automated reading using camera systems might represent a useful tool for standardization. In this study, the ADAGIO automated system (Bio-Rad) was evaluated for reading disk diffusion tests of fastidious bacteria. 144 clinical isolates (68 β-haemolytic streptococci, 28 Streptococcus pneumoniae, 18 viridans group streptococci, 13 Haemophilus influenzae, 7 Moraxella catarrhalis, and 10 Campylobacter jejuni) were tested on Mueller-Hinton agar supplemented with 5% defibrinated horse blood and 20 mg/L β-NAD (MH-F, Oxoid) according to EUCAST. Plates were read manually with a ruler and automatically using the ADAGIO system. Inhibition zone diameters, indicated by the automated system, were visually controlled and adjusted, if necessary. Among 1548 isolate-antibiotic combinations, comparison of automated vs. manual reading yielded categorical agreement (CA) without visual adjustment of the automatically determined zone diameters in 81.4%. In 20% (309 of 1548) of tests it was deemed necessary to adjust the automatically determined zone diameter after visual control. After adjustment, CA was 94.8%; very major errors (false susceptible interpretation), major errors (false resistant interpretation) and minor errors (false categorization involving intermediate result), calculated according to the ISO 20776–2 guideline, accounted to 13.7% (13 of 95 resistant results), 3.3% (47 of 1424 susceptible results) and 1.4% (21 of 1548 total results), respectively, compared to manual reading. The ADAGIO system allowed for automated reading of disk diffusion testing in fastidious bacteria and, after visual validation of the automated results, yielded good categorical agreement with manual reading. PMID:27391898

  7. DNA Sequence Heterogeneity of Campylobacter jejuni CJIE4 Prophages and Expression of Prophage Genes

    PubMed Central

    Clark, Clifford G.; Chong, Patrick M.; McCorrister, Stuart J.; Mabon, Philip; Walker, Matthew; Westmacott, Garrett R.

    2014-01-01

    Campylobacter jejuni carry temperate bacteriophages that can affect the biology or virulence of the host bacterium. Known effects include genomic rearrangements and resistance to DNA transformation. C. jejuni prophage CJIE1 shows sequence variability and variability in the content of morons. Homologs of the CJIE1 prophage enhance both adherence and invasion to cells in culture and increase the expression of a specific subset of bacterial genes. Other C. jejuni temperate phages have so far not been well characterized. In this study we describe investigations into the DNA sequence variability and protein expression in a second prophage, CJIE4. CJIE4 sequences were obtained de novo from DNA sequencing of five C. jejuni isolates, as well as from whole genome sequences submitted to GenBank by other research groups. These CJIE4 DNA sequences were heterogenous, with several different insertions/deletions (indels) in different parts of the prophage genome. Two variants of a 3–4 kb region inserted within CJIE4 had different gene content that distinguished two major conserved CJIE4 prophage families. Additional indels were detected throughout the prophage. Detection of proteins in the five isolates characterized in our laboratory in isobaric Tags for Relative and Absolute Quantitation (iTRAQ) experiments indicated that prophage proteins within each of the two large indel variants were expressed during growth of the bacteria on Mueller Hinton agar plates. These proteins included the extracellular DNase associated with resistance to DNA transformation and prophage repressor proteins. Other proteins associated with known or suspected roles in prophage biology were also expressed from CJIE4, including capsid protein, the phage integrase, and MazF, a type II toxin-antitoxin system protein. Together with the results previously obtained for the CJIE1 prophage these results demonstrate that sequence variability and expression of moron genes are both general properties of temperate

  8. Synthesis and characterization of silver/montmorillonite/chitosan bionanocomposites by chemical reduction method and their antibacterial activity

    PubMed Central

    Shameli, Kamyar; Ahmad, Mansor Bin; Zargar, Mohsen; Yunus, Wan Md Zin Wan; Ibrahim, Nor Azowa; Shabanzadeh, Parvaneh; Moghaddam, Mansour Ghaffari

    2011-01-01

    Silver nanoparticles (AgNPs) of a small size were successfully synthesized using the wet chemical reduction method into the lamellar space layer of montmorillonite/chitosan (MMT/Cts) as an organomodified mineral solid support in the absence of any heat treatment. AgNO3, MMT, Cts, and NaBH4 were used as the silver precursor, the solid support, the natural polymeric stabilizer, and the chemical reduction agent, respectively. MMT was suspended in aqueous AgNO3/Cts solution. The interlamellar space limits were changed (d-spacing = 1.24–1.54 nm); therefore, AgNPs formed on the interlayer and external surface of MMT/Cts with d-average = 6.28–9.84 nm diameter. Characterizations were done using different methods, ie, ultraviolet-visible spectroscopy, powder X-ray diffraction, transmission electron microscopy, scanning electron microscopy, energy dispersive X-ray fluorescence spectrometry, and Fourier transform infrared spectroscopy. Silver/montmorillonite/chitosan bionanocomposite (Ag/MMT/Cts BNC) systems were examined. The antibacterial activity of AgNPs in MMT/Cts was investigated against Gram-positive bacteria, ie, Staphylococcus aureus and methicillin-resistant S. aureus and Gram-negative bacteria, ie, Escherichia coli, E. coli O157:H7, and Pseudomonas aeruginosa by the disc diffusion method using Mueller Hinton agar at different sizes of AgNPs. All of the synthesized Ag/MMT/Cts BNCs were found to have high antibacterial activity. These results show that Ag/MMT/Cts BNCs can be useful in different biological research and biomedical applications, including surgical devices and drug delivery vehicles. PMID:21499424

  9. Molecular detection of metallo-β-lactamase gene blaVIM-1 in imipenem-resistant Pseudomonas aeruginosa strains isolated from hospitalized patients in the hospitals of Isfahan

    PubMed Central

    Sedighi, Mansour; Vaez, Hamid; Moghoofeie, Mohsen; Hadifar, Shima; Oryan, Golfam; Faghri, Jamshid

    2015-01-01

    Background: Pseudomonas aeruginosa is an opportunistic human pathogen that causes serious problems, especially in people, who have immunodeficiency. In recent times, metallo-β-lactamase (MBLs) resistance in this bacterium has led to some difficulties in treating bacterial infections. The metallo-beta-lactamase family of genes, including blaVIM-1, is being reported with increasing frequency worldwide. The aim of this study is the detection of the metallo-β-lactamase gene blaVIM-1 in imipenem-resistant P. aeruginosa (IRPA) strains isolated from hospitalized patients. Materials and Methods: In this study, 106 P. aeruginosa samples were isolated from various nosocomial infections. The isolates were identified, tested for susceptibility to various antimicrobial agents by the Kirby-Bauer disk diffusion method, and all the imipenem-resistant isolates were screened for the presence of MBLs by using the combined disk (IMP-EDTA). The minimal inhibitory concentration (MIC) of imipenem was determined by E-test on the Mueller-Hinton agar. To detect the blaVIM-1 gene, the isolates were subjected to a polymerase chain reaction (PCR). Results: Of all the P. aeruginosa isolates, 62 (58.5%) were found to be imipenem-resistant P. aeruginosa (MIC ≥32 μg/ml). Twenty-six (42%) of the imipenem-resistant isolates were MBL positive. None of these isolates carried the blaVIM-1 gene using the PCR assay. Conclusion: The results demonstrated the serious therapeutic threat of the MBL-producing P. aeruginosa populations. The rate of imipenem resistance due to MBL was increased dramatically. Early detection and infection-control practices are the best antimicrobial strategies for this organism. None of MBL-producing isolates in this study carry the blaVIM-1 gene; therefore, another gene in the MBL family should be investigated. PMID:25802826

  10. Environmental methicillin-resistant Staphylococcus aureus in a veterinary teaching hospital during a nonoutbreak period.

    PubMed

    Hoet, Armando E; Johnson, Amanda; Nava-Hoet, Rocio C; Bateman, Shane; Hillier, Andrew; Dyce, John; Gebreyes, Wondwossen A; Wittum, Thomas E

    2011-06-01

    Concurrent to reports of zoonotic and nosocomial transmission of methicillin-resistant Staphylococcus aureus (MRSA) in veterinary settings, recent evidence indicates that the environment in veterinary hospitals may be a potential source of MRSA. The present report is a cross-sectional study to determine the prevalence of MRSA on specific human and animal contact surfaces at a large veterinary hospital during a nonoutbreak period. A total of 156 samples were collected using Swiffers(®) or premoistened swabs from the small animal, equine, and food animal sections. MRSA was isolated and identified by pre-enrichment culture and standard microbiology procedures, including growth on Mueller-Hinton agar supplemented with NaCl and oxacillin, and by detection of the mecA gene. Staphylococcal chromosome cassette mec (SCCmec) typing and pulsed-field gel electrophoresis profile were also determined. MRSA was detected in 12% (19/157) of the hospital environments sampled. The prevalence of MRSA in the small animal, equine, and food animal areas were 16%, 4%, and 0%, respectively. Sixteen of the MRSA isolates from the small animal section were classified as USA100, SCCmec type II, two of which had pulsed-field gel electrophoresis pattern that does not conform to any known type. The one isolate obtained from the equine section was classified as USA500, SCCmec type IV. The molecular epidemiological analysis revealed a very diverse population of MRSA isolates circulating in the hospital; however, in some instances, multiple locations/surfaces, not directly associated, had the same MRSA clone. No significant difference was observed between animal and human contact surfaces in regard to prevalence and type of isolates. Surfaces touched by multiple people (doors) and patients (carts) were frequently contaminated with MRSA. The results from this study indicate that MRSA is present in the environment even during nonoutbreak periods. This study also identified specific surfaces in a

  11. Comparison of a novel, inhibitor-potentiated disc-diffusion test with other methods for the detection of extended-spectrum beta-lactamases in Escherichia coli and Klebsiella pneumoniae.

    PubMed

    Ho, P L; Chow, K H; Yuen, K Y; Ng, W S; Chau, P Y

    1998-07-01

    A novel, inhibitor-potentiated disc-diffusion test for detecting extended-spectrum beta-lactamases (ESBLs) in bacteria was evaluated. This test uses the principle of augmentation (by > or = 10 mm) of inhibition zones produced by ceftazidime, cefotaxime, ceftriaxone or aztreonam discs on Mueller-Hinton agar supplemented with clavulanate (4 mg/L). The test was initially compared with the double-disc synergy test, Kirby-Bauer disc-diffusion test and Etest ESBL screen with a panel of 45 reference strains with known resistance profiles. This panel consisted of 27 ESBL-positive Escherichia coli strains expressing 14 Bush group 2be enzymes and 18 other E. coli and Klebsiella pneumoniae strains (14 non-ESBL beta-lactamase producers and four non-beta-lactamase producers). The Kirby-Bauer disc-diffusion test was the least sensitive method: 11-44% of the ESBL-positive control strains were misclassified as susceptible to ceftazidime, cefotaxime, ceftriaxone or aztreonam when interpreted by National Committee for Clinical Laboratory Standards (NCCLS) criteria. The sensitivities of the inhibitor-potentiated disc-diffusion test, the double-disc synergy test (when discs were 25 or 30 mm apart) and the Etest ESBL screen (with a breakpoint of > 4-fold reduction in ceftazidime MIC in the presence of clavulanate) were 100%, 96% and 89-96%, respectively. The inhibitor-potentiated disc-diffusion test was further evaluated with 81 E. coli and K. pneumoniae clinical isolates, which were identified as putative ESBL-producers by the double-disc synergy test. For these isolates, the sensitivity of both the inhibitor-potentiated disc-diffusion test and the Etest ESBL screen was 100%. In conclusion, the inhibitor-potentiated disc-diffusion test is a sensitive, convenient and inexpensive method of screening for ESBLs in E. coli and K. pneumoniae isolates, with potential for incorporation into routine clinical laboratory service.

  12. Correlation between the number of Pro-Ala repeats in the EmrA homologue of Acinetobacter baumannii and resistance to netilmicin, tobramycin, imipenem and ceftazidime.

    PubMed

    Nowak-Zaleska, Alicja; Wieczór, Miłosz; Czub, Jacek; Nierzwicki, Łukasz; Kotłowski, Roman; Mikucka, Agnieszka; Gospodarek, Eugenia

    2016-12-01

    Acinetobacter baumannii coccobacilli are dangerous to patients in intensive care units because of their multidrug resistance to antibiotics, developed mainly in the past decade. This study aimed to examine whether there is a significant correlation between the number of Pro-Ala repeats in the CAP01997 protein, the EmrA homologue of A. baumannii, and resistance to antibiotics. A total of 79 multidrug-resistant A. baumannii strains isolated from patients were analysed. Resistance to antibiotics was determined on Mueller-Hinton agar plates using the Kirby-Bauer disk diffusion method. The number of CCTGCA repeats encoding Pro-Ala repeats in CAP01997 was determined by PCR and capillary electrophoresis. The 3D models of CAP01997 containing Pro-Ala repeats were initially generated using RaptorX Structure Prediction server and were assembled with EasyModeller 4.0. The models were embedded in a model bacterial membrane based on structural information from homologous proteins and were refined using 100-ns molecular dynamics simulations. The results of this research show significant correlation between susceptibility to netilmicin, tobramycin and imipenem and the number of repeated Pro-Ala sequences in the CAP01997 protein, a homologue of the Escherichia coli transporter EmrA. Predicted structures suggest potential mechanisms that confer drug resistance by reshaping the cytoplasmic interface between CAP01997 protein and the critical component of the multidrug efflux pump homologous to EmrB. Based on these results, we can conclude that the CAP01997 protein, an EmrA homologue of A. baumannii, confers resistance to netilmicin, tobramycin and imipenem, depending on the number of Pro-Ala repeats.

  13. Is Streptococcus pyogenes Resistant or Susceptible to Trimethoprim-Sulfamethoxazole?

    PubMed Central

    Lilliebridge, Rachael A.; Tong, Steven Y. C.; Baird, Robert W.; Ward, Peter; McDonald, Malcolm I.; Currie, Bart J.; Carapetis, Jonathan R.

    2012-01-01

    Streptococcus pyogenes is commonly believed to be resistant to trimethoprim-sulfamethoxazole (SXT), resulting in reservations about using SXT for skin and soft tissue infections (SSTI) where S. pyogenes is involved. S. pyogenes' in vitro susceptibility to SXT depends on the medium's thymidine content. Thymidine allows S. pyogenes to bypass the sulfur-mediated inhibition of folate metabolism and, historically, has resulted in apparently reduced susceptibility of S. pyogenes to sulfur antibacterials. The low thymidine concentration in Mueller-Hinton agar (MHA) is now regulated. We explored S. pyogenes susceptibility to SXT on various media. Using two sets of 100 clinical S. pyogenes isolates, we tested for susceptibility using SXT Etests on MHA containing defibrinated horse blood and 20 mg/liter β-NAD (MHF), MHA with sheep blood (MHS), MHA alone, MHA with horse blood (MHBA), and MHA with lysed horse blood (MHLHBA). European Committee on Antibacterial Susceptibility Testing (EUCAST) breakpoints defined susceptibility (MIC, ≤1 mg/liter) and resistance (MIC, >2 mg/liter). In study 1, 99% of S. pyogenes isolates were susceptible to SXT on MHA, MHBA, and MHLHBA, with geometric mean MICs of 0.04, 0.04, and 0.05 mg/liter, respectively. In study 2, all 100 S. pyogenes isolates were susceptible to SXT on MHF, MHS, MHA, and MHLHBA with geometric mean MICs of 0.07, 0.16, 0.07, and 0.09 mg/liter, respectively. This study confirms the in vitro susceptibility of S. pyogenes to SXT, providing support for the use of SXT for SSTIs. A clinical trial using SXT for impetigo is ongoing. PMID:23052313

  14. ['In vitro' activity of different antimicrobial agents on Gram-negative nonfermentative bacilli, excluding Pseudomonas aeruginosa and Acinetobacter spp].

    PubMed

    Vay, C A; Almuzara, M N; Rodríguez, C H; Pugliese, M L; Lorenzo Barba, F; Mattera, J C; Famiglietti, A M R

    2005-01-01

    Gram-negative nonfermentative bacilli (NFB) are widely spread in the environment. Besides of difficulties for identification, they often have a marked multiresistance to antimicrobial agents, including those active against Pseudomonas aeruginosa. The objective of this study was to evaluate the 'in vitro' activity of different antimicrobial agents on 177 gram-negative nonfermentative bacilli isolates (excluding Pseudomonas aeruginosa and Acinetobacter spp.) isolated from clinical specimens. Minimum inhibitory concentrations (MIC) were determined according to the Mueller Hinton agar dilution method against the following antibacterial agents: ampicillin, piperacillin, piperacillin-tazobactam, sulbactam, cefoperazone, cefoperazone-sulbactam, ceftazidime, cefepime, aztreonam, imipenem, meropenem, colistin, gentamicin, amikacin, trimethoprim-sulfamethoxazole, chloramphenicol, erythromycin, rifampin, norfloxacin, ciprofloxacin and minocycline. Seven isolates: Sphingobacterium multivorum (2), Sphingobacteriumspiritivorum (1), Empedobacterbrevis (1), Weeksella virosa (1), Bergeyella zoohelcum (1) and Oligella urethralis (1), were tested for amoxicillin-clavulanic acid and ampicillin-sulbactam susceptibility, and susceptibility to cefoperazone or sulbactam was not determined. Multiresistance was generally found in Stenotrophomonas maltophilia, Burkholderia cepacia, Chryseobacterium spp., Myroides spp., Achromobacter xylosoxidans, and Ochrobactrum anthropi isolates. On the other hand, Pseudomonas stutzeri, Shewanella putrefaciens-algae, Sphingomonas paucimobilis, and Pseudomonas oryzihabitans, Bergeyella zoohelcum, Weeksella virosa and Oligella urethralis were widely susceptible to the antibacterial agents tested. As a result of the wide variation in antimicrobial susceptibility shown by different species, a test on susceptibility to different antibacterial agents is essential in order to select an adequate therapy. The marked multiresistance evidenced by some species

  15. Evaluation of Antimicrobial Effects of Different Concentrations of Triple Antibiotic Paste on Mature Biofilm of Enterococcus faecalis

    PubMed Central

    Frough Reyhani, Mohammad; Rahimi, Saeed; Fathi, Zahra; Shakouie, Sahar; Salem Milani, Amin; Soroush Barhaghi, Mohammad Hossein; Shokri, Javad

    2015-01-01

    Background and aims. Triple antibiotic paste (TAP) is widely used in endodontics for root canal disinfection, particularly in regenerative procedures. The aim of this in vitro study was to evaluate the antimicrobial effects of different concentrations of TAP at 1-, 2-, 3-, and 4-week intervals on mature Enterococcus faecalis biofilm. Materials and methods. A total of 287 extracted one-rooted human central incisors were infected with E. faecalis ATCC 29212 after removing the crown and preparation. The root canal space was filled with one of the 0.01-, 0.1-, 1-, 10-, 100-, and 1000-mg/mL concentrations of TAP or normal saline (control). The root canal dentin was sampled after 1, 2, 3, and 4 weeks. The dentinal shavings were cultured on Mueller-Hinton agar plates after serial dilutions. The classic colony-forming unit (CFU) counting technique was used to determine remaining bacterial counts. Data were analyzed by using the two-way ANOVA, post hoc Tukey tests and one-way ANOVA (P<0.05). Results. TAP completely eliminated E. faecalis biofilms at all the intervals at concentrations of 1000, 100, and 10 mg/mL, whereas 1-, 0.1-, and 0.01-mg/mL TAP resulted in significant reduction of CFU means compared with the control group. There were no statistically significant differences between the four time intervals. Conclusion. Use of lower concentrations of TAP at short term could eradicate E. faecalis biofilm and decrease high-concentration side effects. PMID:26697145

  16. The in Vitro Antibacterial Efficacy of Persian Green Tea Extract as an Intracanal Irrigant on Enterococcus faecalis Biofilm

    PubMed Central

    Ramezanali, Fatemeh; Samimi, Shiva; Kharazifard, Mohammadjavad; Afkhami, Farzaneh

    2016-01-01

    Introduction: The aim of this study was to compare the antibacterial effect of Persian green tea extract (GTE) and 2.5% sodium hypochlorite (NaOCl) against Enterococcus faecalis (E. faecalis) as an intracanal irrigant. Methods and Materials: Thirty freshly extracted teeth were instrumented and sectioned into mesial and distal segments. The specimens were put into wells containing 2 mL of E. faecalis-containing medium. After 3 weeks, the specimens were removed and divided randomly into three groups (n=20). Each group was exposed to 3 mL of different irrigants for 3 min. Groups 1, 2 and 3 were irrigated with GTE, 2.5% NaOCl and normal saline, respectively. Biofilm formed in the middle third of the root canal was carved by sterile scalpel and cultured in Mueller-Hinton medium. Number of colony forming units (CFU) was counted on each plate. In addition, antimicrobial activity of the irrigants was evaluated by the agar disc diffusion test. The diameter of inhibition zone (IZ) around each irrigant was evaluated. The Kruskal-Wallis and Dunn tests were used to analysis the data. Results: While in NaOCl group no bacterial colonies were observed, the mean number of E. faecalis in GTE and control groups were 275±74 CFU/mL (P<0.001) and 119×108±11×108 (P<0.001), respectively. The mean of IZ in NaOCl and GTE groups were 24.35±0.78 and 6.9±0.87 mm, in order of appearance (P<0.001). Zone of inhibition was not observed around the control group (P<0.001). Conclusion: This research highlighted the potential role of plant extracts in antimicrobial root canal irrigation protocol. PMID:27790260

  17. Inactivation efficiency and mechanism of UV-TiO2 photocatalysis against murine norovirus using a solidified agar matrix.

    PubMed

    Park, Daseul; Shahbaz, Hafiz Muhammad; Kim, Sun-Hyoung; Lee, Mijin; Lee, Wooseong; Oh, Jong-Won; Lee, Dong-Un; Park, Jiyong

    2016-12-05

    Human norovirus (HuNoV) is the primary cause of viral gastroenteritis worldwide. Fresh blueberries are among high risk foods associated with norovirus related outbreaks. Therefore, it is important to assess intervention strategies to reduce the risk of foodborne illness. The disinfection efficiency of decontamination methods is difficult to evaluate for fruits and vegetables due to an inconsistent degree of contamination and irregular surface characteristics. The inactivation efficiency and mechanism of murine norovirus 1 (MNV-1, a surrogate for HuNoV) was studied on an experimentally prepared solidified agar matrix (SAM) to simulate blueberries using different wavelengths (A, B, C) of UV light both with and without TiO2 photocatalysis (TP). MNV-1 was inoculated on exterior and interior of SAM and inactivation efficiencies of different treatments were investigated using a number of assays. Initial inoculum levels of MNV-1 on the SAM surface and interior were 5.2logPFU/mL. UVC with TiO2 (UVC-TP) achieved the highest level of viral reduction for both externally inoculated and internalized MNV-1. Externally inoculated MNV-1 was reduced to non-detectable levels after UVC-TP treatment for 5min while there was still a 0.9 log viral titer after UVC alone. For internalized MNV-1, 3.2 log and 2.7 log reductions were obtained with UVC-TP and UVC alone treatments for 10min, respectively. The Weibull model was applied to describe the inactivation behavior of MNV-1, and the model showed a good fit to the data. An excellent correlation between the steady-state concentration of OH radicals ([OH]ss) and viral inactivation was quantified using a para-chlorobenzoic acid (pCBA) probe compound, suggesting that OH radicals produced in the UV-TP reaction were the major species for MNV-1 inactivation. Transmission electron microscopy images showed that the structure of viral particles was completely disrupted with UVC-TP and UVC alone. SDS-PAGE analysis showed that the major capsid

  18. Comparison of CHROMagar Salmonella Medium and Xylose-Lysine-Desoxycholate and Salmonella-Shigella Agars for Isolation of Salmonella Strains from Stool Samples

    PubMed Central

    Maddocks, Susan; Olma, Tom; Chen, Sharon

    2002-01-01

    The growth and appearance of 115 stock Salmonella isolates on a new formulation of CHROMagar Salmonella (CAS) medium were compared to those on xylose-lysine-desoxycholate agar (XLD), Salmonella-Shigella agar (SS), and Hektoen enteric agar (HEA) media. CAS medium was then compared prospectively to XLD and SS for the detection and presumptive identification of Salmonella strains in 500 consecutive clinical stool samples. All stock Salmonella isolates produced typical mauve colonies on CAS medium. Nine Salmonella strains were isolated from clinical specimens. The sensitivities for the detection of salmonellae after primary plating on CAS medium and the combination of XLD and SS after enrichment were 100%. The specificity for the detection of salmonellae after primary plating on CAS medium (83%) was significantly (P < 0.0001) higher than that after primary plating on the combination of SS and XLD media (55%) (a 28% difference in rates; 95% confidence interval, 23.0 to 34%). Twenty-nine non-Salmonella organisms produced mauve colonies on CAS medium, including 17 Candida spp. (59%) and 8 Pseudomonas spp. (28%). These were easily excluded as salmonellae by colony morphology, microscopic examination of a wet preparation, or oxidase testing. One biochemically inert Escherichia coli isolate required further identification to differentiate it from Salmonella spp. The use of plating on CAS medium demonstrated high levels of sensitivity and specificity and reduced the time to final identification of Salmonella spp., resulting in substantial cost savings. It can be recommended for use for the primary isolation of Salmonella spp. from stool specimens. Other media (e.g., XLD) are required to detect Shigella spp. concurrently. PMID:12149365

  19. Evaluating survival of Escherichia coli O157:H7 in frozen and thawed apple cider: potential use of a hydrophobic grid membrane filter-SD-39 agar method.

    PubMed

    Sage, J R; Ingham, S C

    1998-04-01

    To determine the susceptibility of Escherichia coli O157:H7 to freezing and thawing in apple cider, methods that recover injured cells are needed for accurate enumeration. This study compared the ISO-GRID hydrophobic grid membrane filter (HGMF) SD-39 agar method to two other methods: a reference most probable number (MPN) method, and plating on sorbitol MacConkey agar (SMA). To determine numbers of injured cells, SMA spread plating was also compared to Trypticase soy agar (TSA) spread plating. Two strains of E. coli O157:H7 QA 326 and ATCC 43895, were inoculated into presterilized apple cider (10 ml) which was then frozen (-20 degrees C for 24 h). Samples were thawed at 4 degrees C for 4 h, or at 23 degrees C for 1.5 h, or in a microwave oven (700 W for 10 s). Substantial cell death (0.69- to 6.33 log10 CFU/ml decreases) and injury (0.70- to 2.38-log10 CFU/ml decreases) occurred during freezing and thawing. The extent of death and injury varied with strain and thawing method. The TSA spread plating method recovered the most cells while the HGMF method always recovered more viable cells than the reference MPN method and also either recovered significantly more (P < 0.05) cells or a not significantly different number of cells than SMA spread plating. Some injured cells of both strains were not counted by the HGMF method. Significant numbers of cells injured by freezing and thawing at 4 degrees C in apple cider were enumerated in the cider was diluted 1:2 Trypticase soy broth immediately before plating. Two epifluorescent microscopic methods showed that injury was not associated with loss of cell membrane integrity.

  20. Effect of post-treatments and concentration of cotton linter cellulose nanocrystals on the properties of agar-based nanocomposite films.

    PubMed

    Oun, Ahmed A; Rhim, Jong-Whan

    2015-12-10

    Cellulose nanocrystals (CNCs) were prepared by acid hydrolysis of cotton linter pulp fibers and three different purification methods, i.e., without post purification (CNC1), dialyzed against distilled water (CNC2), and neutralized with NaOH (CNC3), and their effect on film properties was evaluated by preparation of agar/CNCs composite films. All the CNCs were rod in shape with diameter of 15-50 nm and length of 210-480 nm. FTIR result indicated that there was no distinctive differences in the chemical structure between CNCs and cotton linter cellulose fiber. No significant relationship was observed between the sulfate content and crystallinity index of CNCs. The CNC3 showed higher thermal stability than the other type of CNCs due to the less adverse effect on the thermal stability of sulfate groups induced by the neutralization with NaOH. The tensile strength (TS) of agar film increased by 15% with incorporation of 5 wt% of CNC3, on the contrary, it decreased by 10% and 15% with incorporation of CNC1 and CNC2, respectively. Other performance properties of agar/CNCs composite films such as optical and water vapor barrier properties showed that the CNC3 was more effective filler than the other CNCs. In the range of concentration of CNC3 tested (1-10 wt%), inclusion of 5 wt% of CNC3 was the maximum concentration for improving or maintaining film properties of the composite films. The neutralization of acid hydrolyzed cellulose using NaOH was simple and convenient for the preparation of CNC and bionanocomposite films.

  1. Combined Use of Pastorex Staph-Plus and Either of Two New Chromogenic Agars, MRSA ID and CHROMagar MRSA, for Detection of Methicillin-Resistant Staphylococcus aureus▿

    PubMed Central

    Compernolle, Veerle; Verschraegen, Gerda; Claeys, Geert

    2007-01-01

    We describe the search toward a fast and reliable strategy to detect and confirm the presence of methicillin-resistant Staphylococcus aureus (MRSA) in screening samples. First, we evaluated the sensitivities and specificities of oxacillin resistance screening agar (ORSA) with enrichment (tryptic soy broth [TSB] and ORSA [TSB-ORSA]) and without enrichment (ORSA), MRSA ID (MRSA_ID) plates, and CHROMagar MRSA (C_MRSA) plates, all of which were inoculated with equal volumes of a suspension made by emulsifying screening swabs. Whereas the sensitivities after 48 h were similar for all media tested (77% for MRSA_ID and ORSA; 73% for C_MRSA and ORSA after enrichment [TSB-ORSA]), the specificities of MRSA_ID (98% after 24 h and 94% after 48 h) and C_MRSA (98% after 24 h and 90% after 48 h) were superior to the specificities of ORSAs (92% after 24 h and 83% after 48 h) and TSB-ORSA (86% after 24 h and 81% after 48 h). Subsequently, the performance of the Pastorex Staph-Plus agglutination test with presumptive MRSA isolates taken directly from chromogenic agars (direct_Pastorex agglutination) was compared to that of the Pastorex Staph-Plus agglutination test with isolates from blood agar subcultures (conventional_Pastorex agglutination). When the direct_Pastorex agglutination test on MRSA_ID plates was combined with Gram staining, the direct_Pastorex agglutination test with samples from MRSA_ID plates was as reliable as the conventional_Pastorex agglutination test with samples from blood agar subcultures from MRSA_ID plates. In contrast, the direct_Pastorex agglutination test with samples from C_MRSA plates gave false-negative results. Finally, we calculated the processing times of the four different strategies, namely, (i) enrichment in TSB supplemented with NaCl, subsequent culture on ORSA, and the conventional_Pastorex agglutination test; (ii) direct inoculation of ORSA combined with conventional_Pastorex agglutination test; (iii) direct inoculation of MRSA_ID plates

  2. Trisodium phosphate and sodium hypochlorite are more effective as antimicrobials against Campylobacter and Salmonella on duck as compared to chicken meat.

    PubMed

    Sarjit, Amreeta; Dykes, Gary A

    2015-06-16

    Little work has been reported on the use of commercial antimicrobials against foodborne pathogens on duck meat. We investigated the effectiveness of trisodium phosphate (TSP) and sodium hypochlorite (SH) as antimicrobial treatments against Campylobacter and Salmonella on duck meat under simulated commercial water chilling conditions. The results were compared to the same treatments on well-studied chicken meat. A six strain Campylobacter or Salmonella cocktail was inoculated (5 ml) at two dilution levels (10(4) and 10(8) cfu/ml) onto 25 g duck or chicken meat with skin and allowed to attach for 10 min. The meat was exposed to three concentrations of pH adjusted TSP (8, 10 and 12% (w/v), pH 11.5) or SH (40, 50 and 60 ppm, pH 5.5) in 30 ml water under simulated spin chiller conditions (4 °C, agitation) for 10 min. In a parallel experiment the meat was placed in the antimicrobial treatments before inoculation and bacterial cocktails were added to the meat after the antimicrobial solution was removed while all other parameters were maintained. Untreated controls and controls using water were included in all experiments. Bacterial numbers were determined on Campylobacter blood-free selective agar and Mueller Hinton agar or xylose deoxycholate agar and tryptone soya agar using the thin agar layer method for Campylobacter and Salmonella, respectively. All TSP concentrations significantly (p<0.05) reduced numbers of Campylobacter (~1.2-6.4 log cfu/cm(2)) and Salmonella (~0.4-6.6 log cfu/cm(2)) on both duck and chicken meat. On duck meat, numbers of Campylobacter were less than the limit of detection at higher concentrations of TSP and numbers of Salmonella were less than the limit of detection at all concentrations of TSP except one. On chicken meat, numbers of Campylobacter and Salmonella were less than the limit of detection only at the lower inoculum level and higher TSP concentrations. By contrast only some of the concentrations of SH significantly (p<0.05) reduced

  3. The fungicidal and phytotoxic properties of benomyl and PPM in supplemented agar media supporting transgenic arabidopsis plants for a Space Shuttle flight experiment

    NASA Technical Reports Server (NTRS)

    Paul, A. L.; Semer, C.; Kucharek, T.; Ferl, R. J.

    2001-01-01

    Fungal contamination is a significant problem in the use of sucrose-enriched agar-based media for plant culture, especially in closed habitats such as the Space Shuttle. While a variety of fungicides are commercially available, not all are equal in their effectiveness in inhibiting fungal contamination. In addition, fungicide effectiveness must be weighed against its phytotoxicity and in this case, its influence on transgene expression. In a series of experiments designed to optimize media composition for a recent shuttle mission, the fungicide benomyl and the biocide "Plant Preservative Mixture" (PPM) were evaluated for effectiveness in controlling three common fungal contaminants, as well as their impact on the growth and development of arabidopsis seedlings. Benomyl proved to be an effective inhibitor of all three contaminants in concentrations as low as 2 ppm (parts per million) within the agar medium, and no evidence of phytotoxicity was observed until concentrations exceeded 20 ppm. The biocide mix PPM was effective as a fungicide only at concentrations that had deleterious effects on arabidopsis seedlings. As a result of these findings, a concentration of 3 ppm benomyl was used in the media for experiment PGIM-01 which flew on shuttle Columbia mission STS-93 in July 1999.

  4. Evaluation of side effects of radiofrequency capacitive hyperthermia with magnetite on the blood vessel walls of tumor metastatic lesion surrounding the abdominal large vessels: an agar phantom study

    PubMed Central

    2014-01-01

    Background Magnetite used in an 8-MHz radiofrequency (RF) capacitive heating device can increase the temperature of a specific site up to 45°C. When treating a metastatic lesion around large abdominal vessels via hyperthermia with magnetite, heating-induced adverse effects on these vessels need to be considered. Therefore, this study examined hyperthermia-induced damage to blood vessel walls in vitro. Methods A large agar phantom with a circulatory system consisting of a swine artery and vein connected to a peristaltic pump was prepared. The blood vessels were placed on the magnetite-containing agar piece. Heating was continued for 30 min at 45°C. After heating, a histological study for injury to the blood vessels was performed. Results The inner membrane temperature did not reach 45°C due to the cooling effect of the blood flow. In the heated vessels, vascular wall collagen degenerated and smooth muscle cells were narrowed; however, no serious changes were noted in the vascular endothelial cells or vascular wall elastic fibers. The heated vessel wall was not severely damaged; this was attributed to cooling by the blood flow. Conclusions Our findings indicate that RF capacitive heating therapy with magnetite may be used for metastatic lesions without injuring the surrounding large abdominal vessels. PMID:25114787

  5. Improvement of Polymyxin-Egg Yolk-Mannitol-Bromothymol Blue Agar for the Enumeration and Isolation of Bacillus cereus in Various Foods.

    PubMed

    Kang, Il-Byeong; Chon, Jung-Whan; Kim, Dong-Hyeon; Jeong, Dana; Kim, Hong-Seok; Kim, Hyunsook; Seo, Kun-Ho

    2017-03-01

    A modified polymyxin-egg yolk-mannitol-bromothymol blue agar (mPEMBA) was developed by supplementing polymyxin-egg yolk-mannitol-bromothymol blue agar (PEMBA) with trimethoprim to improve the selectivity for and recoverability of Bacillus cereus from naturally and artificially contaminated food samples. The number of B. cereus in mPEMBA was significantly higher than in PEMBA, indicating better recoverability (P < 0.05) in red pepper powder (PEMBA 0.80 ± 0.22 log CFU/g versus mPEMBA 1.95 ± 0.17 log CFU/g) and soybean paste (PEMBA 2.19 ± 0.18 log CFU/g versus mPEMBA 3.09 ± 0.13 log CFU/g). In addition, mPEMBA provided better visual differentiation of B. cereus colonies than PEMBA, which is attributable to the reduced number of competing microflora. We conclude that the addition of trimethoprim to PEMBA could generate a synergistic effect to improve selectivity for B. cereus .

  6. In vitro susceptibility of Burkholderia cepacia complex isolates: Comparison of disk diffusion, Etest®, agar dilution, and broth microdilution methods.

    PubMed

    Fehlberg, Lorena Cristina Corrêa; Nicoletti, Adriana Gianinni; Ramos, Ana Carolina; Rodrigues-Costa, Fernanda; de Matos, Adriana Pereira; Girardello, Raquel; Marques, Elizabeth Andrade; Gales, Ana Cristina

    2016-12-01

    Broth microdilution, agar dilution, Etest® and disk diffusion techniques were compared to evaluate the susceptibility profile of 82 Bcc clinical isolates against six antimicrobials as recommended by CLSI. Broth microdilution was considered the "gold standard" method. The regression analysis was applied to determine the essential (EA) and categorical (CA) agreement rates. STX (MIC50, 1 mg/L) was the most potent antimicrobial tested against Bcc isolates. The worst in vitro activity was observed for chloramphenicol (MIC50, 16 mg/L) and ticarcillin-clavulanic acid (MIC50, >256 mg/L). The EA among broth microdilution and agar dilution results was good for the majority of antimicrobial tested. When comparing broth microdilution and Etest®, ceftazidime, SXT and chloramphenicol exhibited EA rates below 90%. SXT showed an excellent CA (100%) when dilution methodologies were compared. However, a low CA rate was found for this agent between dilution and disk diffusion methodologies resulting in unacceptable very major and minor error rates.

  7. The fungicidal and phytotoxic properties of benomyl and PPM in supplemented agar media supporting transgenic arabidopsis plants for a Space Shuttle flight experiment.

    PubMed

    Paul, A L; Semer, C; Kucharek, T; Ferl, R J

    2001-05-01

    Fungal contamination is a significant problem in the use of sucrose-enriched agar-based media for plant culture, especially in closed habitats such as the Space Shuttle. While a variety of fungicides are commercially available, not all are equal in their effectiveness in inhibiting fungal contamination. In addition, fungicide effectiveness must be weighed against its phytotoxicity and in this case, its influence on transgene expression. In a series of experiments designed to optimize media composition for a recent shuttle mission, the fungicide benomyl and the biocide "Plant Preservative Mixture" (PPM) were evaluated for effectiveness in controlling three common fungal contaminants, as well as their impact on the growth and development of arabidopsis seedlings. Benomyl proved to be an effective inhibitor of all three contaminants in concentrations as low as 2 ppm (parts per million) within the agar medium, and no evidence of phytotoxicity was observed until concentrations exceeded 20 ppm. The biocide mix PPM was effective as a fungicide only at concentrations that had deleterious effects on arabidopsis seedlings. As a result of these findings, a concentration of 3 ppm benomyl was used in the media for experiment PGIM-01 which flew on shuttle Columbia mission STS-93 in July 1999.

  8. Effects of PVA, agar contents, and irradiation doses on properties of PVA/ws-chitosan/glycerol hydrogels made by γ-irradiation followed by freeze-thawing

    NASA Astrophysics Data System (ADS)

    Yang, Xiaomin; Zhu, Zhiyong; Liu, Qi; Chen, Xiliang; Ma, Mingwang

    2008-08-01

    Poly(vinyl alcohol) (PVA)/water soluble chitosan (ws-chitosan)/glycerol hydrogels were prepared by γ-irradiation and γ-irradiation followed by freeze-thawing, respectively. The effects of irradiation dose and the contents of PVA and agar on the swelling, rheological, and thermal properties of these hydrogels were investigated. The swelling capacity decreases while the mechanical strength increases with increasing PVA or agar content. Increasing the irradiation dose leads to an increase in chemical crosslinking density but a decrease in physical crosslinking density. Hydrogels made by irradiation followed by freeze-thawing own smaller swelling capacity but larger mechanical strength than those made by pure irradiation. The storage modulus of the former hydrogels decreases above 50 °C and above 70 °C it comes to the same value as that prepared by irradiation. The ordered association of PVA is influenced by both chemical and physical crosslinkings and by the presence of ws-chitosan and glycerol. These hydrogels are high sensitive to pH and ionic strength, indicating that they may be useful in stimuli-responsive drug release system.

  9. [Evaluation of the Yersinia enterocolitica pathogenicity through some phenotypic and genotypic characters: CRMOX agar positivity and presence of the ail gene].

    PubMed

    Sacco, C; Ciapini, A; Santomauro, F; Dei, R; Donato, R

    2005-01-01

    Sixty-nine strains of Y. enterocolitica isolated from environmental and human matrices (waste water, food and faeces) were studied in order to evidence the presence of ail gene, calcium-dependency and Congo Red absorption for pathogenic strains identification. Out of 24 clinical strains, the ail gene was present in 21 (87%), among which 79% were CRMOX-positive as well. On the contrary, none of the 45 environmental strains showed the ail gene although only one (isolated from cooked vegetables) was CRMOX agar positive. Our results confirmed the importance of molecular methods to evidence the Y. enterocolitica pathogenic strains. However, our study pointed also the utility to consider the approach of classic bacteriology, like the subcoltivation on CRMOX agar to show calcium-dependency and Congo Red absorption. In particular, when dealing with environmental isolates, that medium will be useful as a preliminary screening to identify those isolates which need further research to indicate their pathogenic potential by the use of more complex but also more expensive molecular methods.

  10. Potential application of extracts from Indian almond (Terminalia catappa Linn.) leaves in Siamese fighting fish (Betta splendens Regan) culture.

    PubMed

    Purivirojkul, Watchariya

    2012-01-01

    Indian almond (Terminalia catappa Linn.) leaves with green and red coloration were tested for bactericidal activity with pathogenic bacteria and their acute toxicity to Siamese fighting fish (Betta splendens Regan). Powder of Indian almond leaves was extracted with water at the ratio of 1:10 (w/v) and then freeze-dried to a dry powder. Bactericidal efficacy was tested against 28 isolates of pathogenic bacteria (Aeromonas hydrophila, Edwardsiella tarda, Enterobacter spp., Plesiomonas shigelloides, Pseudomonas spp., Shewanella putrefaciens, Staphylococcus sp. and Streptococcus sp.) isolated from Siamese fighting fish. A paper disc diffusion method was tested on Mueller Hinton Agar (MHA) by inoculating 1 x 106 CFU/mL of each bacterial suspension. Paper disks (5 mm) were impregnated with either 10 microl of green or red Indian almond leaf extract at a concentration of 12,000 ppm, then laid on the surface of the MHA. The results revealed that aqueous extract of red Indian almond leaves could inhibit the growth of tested bacteria better than the green extract. The minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) were determined. Extracts of green and red leaves were diluted in Mueller Hinton Broth (MHB) to obtain a starting extract concentration of 6,000 ppm then twofold serially diluted in a 96-well microtitre plate. The pathogenic bacteria were inoculated into each well at a density of 1 x 105 CFU/mL and incubated at 35 degrees C for 24 h. The growth of bacteria was detected by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazoliium bromide. The MIC of the red leaf extract ranged from 187.5 to 375 ppm which was lower than for green leaf extract (375-750 ppm). The MBC range of the red leaf extract was 375-750 ppm which was lower than for the green leaf extract (750-1,500 ppm). Acute toxicity tests (96-h LC50) of Indian almond green and red leaf water extracts in Siamese fighting fish were conducted. A logarithmic-spaced series of Indian

  11. Serological differentiation of Brucella-vaccinated and -infected domesticated animals by the agar gel immunodiffusion test using Brucella polysaccharide in mongolia.

    PubMed

    Erdenebaatar, Janchivdorj; Sugar, Sengee; Yondondorj, Agchbazar; Nagabayashi, Toshihiko; Syuto, Bunei; Watarai, Masahisa; Makino, Sou-Ichi; Shirahata, Toshikazu

    2002-09-01

    To investigate Brucella infection in cattle, sheep, goat, reindeer and yak in Mongolia, serological reactions of Brucella-infected and -vaccinated domestic animals were compared by the agar gel immunodiffusion (AGID) test with a polysaccharide (poly-B) of the B. Abortus strain S-19. The sensitivity and specificity were compared with conventional serological tests that are commonly used in Mongolia, such as the rose Bengal test, the tube agglutination test and the compliment fixation test. A total of 73.3, 100, 100, 95.8 and 61.9% of the sera from suspected cattle, yak, goat, sheep and reindeer, respectively, that were positive in the compliment fixation test, were also positive in the AGID test. Sera from vaccinated cattle, sheep and goat were positive over 90% by conventional tests 3 months after vaccination, but were negative by the AGID. These results suggest that the AGID test may be useful to differentiate infected and vaccinated animals in the field.

  12. Bioactive polyketides isolated from agar-supported fermentation of Phomopsis sp. CMU-LMA, taking advantage of the scale-up device, Platotex.

    PubMed

    Adelin, Emilie; Martin, Marie-Thérèse; Cortial, Sylvie; Retailleau, Pascal; Lumyong, Saisamorn; Ouazzani, Jamal

    2013-09-01

    Phomopsis sp. CMU-LMA was cultivated on agar-supported fermentation (Ag-SF) using the scale-up prototype Platotex. In total nine compounds were isolated from the ethyl acetate extract of the culture. Among them, compounds LMA-P1, Sch-642305, DHTO and LMA-P2 had already been reported in our previous work on liquid state fermentation. The trihydroxybenzene lactone cytosporone D and dothiorelone A has been recently isolated from Phomopsis and Magnaporthe species. In addition, three compounds were isolated consisting in the reduced methoxy derivative of Sch-642305 (1), a hydroxylated derivative of LMA-P2 (2) and a linear ethyl ester polyketide (3) similar to the previously reported LMA-P3. Antimicrobial activity and inhibition of Escherichia coli DnaG primase were investigated. Cytosporone D inhibited the E. coli DnaG primase, a Gram-negative antimicrobial target, with an IC50 of 0.25 mM.

  13. Time-resolved x-ray imaging of high-power laser-irradiated under-dense silica aerogels and agar foams

    SciTech Connect

    Koch, J.A.; Estabrook, K.G.; Bauer, J.D.

    1995-08-01

    This paper presents the results of experiments in which a high-power laser was used to irradiate low density (4 - 9 mg/cm{sup 3}) silica aerogel and agar foam targets. The laser-solid interaction and energy transport through the material were monitored with time-resolved imaging diagnostics, and the data show the production and propagation of an x-ray emission front in the plasma. The emission-front trajectory data are found to be in significant disagreement with detailed simulations, which predict a much more rapid heating of the cold material, and the data suggest that this discrepancy is not explainable by target inhomogeneities. Evidence suggests that energy transport into the cold material may be dominated by thermal conduction; however, no completely satisfactory explanation for the discrepancies is identified, and further experimental and theoretical research is necessary in order to resolve this important problem in laser-plasma interaction physics.

  14. Standardized methods and quality control limits for agar and broth microdilution susceptibility testing of Mycoplasma pneumoniae, Mycoplasma hominis, and Ureaplasma urealyticum.

    PubMed

    Waites, Ken B; Duffy, Lynn B; Bébéar, Cécile M; Matlow, Anne; Talkington, Deborah F; Kenny, George E; Totten, Patricia A; Bade, Donald J; Zheng, Xiaotian; Davidson, Maureen K; Shortridge, Virginia D; Watts, Jeffrey L; Brown, Steven D

    2012-11-01

    An international multilaboratory collaborative study was conducted to develop standard media and consensus methods for the performance and quality control of antimicrobial susceptibility testing of Mycoplasma pneumoniae, Mycoplasma hominis, and Ureaplasma urealyticum using broth microdilution and agar dilution techniques. A reference strain from the American Type Culture Collection was designated for each species, which was to be used for quality control purposes. Repeat testing of replicate samples of each reference strain by participating laboratories utilizing both methods and different lots of media enabled a 3- to 4-dilution MIC range to be established for drugs in several different classes, including tetracyclines, macrolides, ketolides, lincosamides, and fluoroquinolones. This represents the first multilaboratory collaboration to standardize susceptibility testing methods and to designate quality control parameters to ensure accurate and reliable assay results for mycoplasmas and ureaplasmas that infect humans.

  15. Evaluation of a novel chromogenic agar medium for isolation and differentiation of vancomycin-resistant Enterococcus faecium and Enterococcus faecalis isolates.

    PubMed

    Ledeboer, Nathan A; Das, Kingshuk; Eveland, Michael; Roger-Dalbert, Céline; Mailler, Sandrine; Chatellier, Sonia; Dunne, William Michael

    2007-05-01

    The development of reliable and rapid methods for the identification of patients colonized with vancomycin-resistant enterococci (VRE) is central to the containment of this agent within a hospital environment. To this end, we evaluated a prototype chromogenic agar medium (VRE-BMX; bioMérieux, Marcy l'Etoile, France) used to recover VRE from clinical specimens. This medium can also identify isolated colonies as either vancomycin-resistant Enterococcus faecium or Enterococcus faecalis, based on distinct colony colors. We compared the performance of VRE-BMX with bile esculin azide agar supplemented with vancomycin (BEAV). For this study, 147 stool samples were plated on each test medium and examined after 24 and 48 h of incubation. At 24 h, the sensitivity and specificity of each medium were as follows: BEAV, 90.9% and 89.9%, respectively; VRE-BMX, 96.4% and 96.6%, respectively. The positive predictive values (PPV) of VRE-BMX and BEAV at 24 h were 89.8% and 80.7%, respectively. VRE-BMX provided the identification of 10 isolates of vancomycin-resistant E. faecalis and 4 isolates of vancomycin-resistant E. faecium that were not recovered by BEAV. Further, VRE-BMX was capable of identifying patients colonized with both E. faecium and E. faecalis, a feature useful for infection control purposes that is not a function of BEAV. In terms of the recovery of vancomycin-resistant E. faecium and E. faecalis, the sensitivity and PPV were as follows: BEAV, 75.7% and 74.6%, respectively; VRE-BMX, 95.5% and 91.3%, respectively. In this initial evaluation, we found that VRE-BMX provided improved recovery of VRE from stool specimens, with the added advantage of being able to differentiate between vancomycin-resistant E. faecalis and E. faecium. Extending the incubation period beyond 24 h did not significantly improve the recovery of VRE and resulted in decreased specificity.

  16. Soft-agar-coated filter method for early detection of viable and thermostable direct hemolysin (TDH)- or TDH-related hemolysin-producing Vibrio parahaemolyticus in seafood.

    PubMed

    Hayashi, Sachiko; Okura, Masatoshi; Osawa, Ro

    2006-07-01

    A novel method for detecting viable and thermostable direct hemolysin (TDH)-producing or TDH-related hemolysin (TRH)-producing Vibrio parahaemolyticus in seafood was developed. The method involved (i) enrichment culture, selective for viable, motile cells penetrating a soft-agar-coated filter paper, and (ii) a multiplex PCR assay targeting both the TDH gene (tdh) and TRH gene (trh) following DNase pretreatment on the test culture to eradicate any incidental DNAs that might have been released from dead cells of tdh- or trh-positive (tdh+ trh+) strains and penetrated the agar-coated filter. A set of preliminary laboratory tests performed on 190 ml of enrichment culture that had been inoculated simultaneously with ca. 100 viable cells of a strain of tdh+ trh+ V. parahaemolyticus and dense populations of a viable strain of tdh- and trh-negative V. parahaemolyticus or Vibrio alginolyticus indicated that the method detected the presence of viable tdh+ trh+ strains. Another set of preliminary tests on 190 ml of enrichment culture that had been initially inoculated with a large number of dead cells of the tdh+ trh+ strain together with dense populations of the tdh- and trh-negative strains confirmed that the method did not yield any false-positive results. Subsequent quasi-field tests using various seafood samples (ca. 20 g), each of which was experimentally contaminated with either or both hemolysin-producing strains at an initial density of ca. 5 to 10 viable cells per gram, demonstrated that contamination could be detected within 2 working days.

  17. Evaluation of CHROMagar STEC and STEC O104 Chromogenic Agar Media for Detection of Shiga Toxin-Producing Escherichia coli in Stool Specimens

    PubMed Central

    Ruckly, Corinne; Carle, Isabelle; Lejay-Collin, Monique

    2013-01-01

    The performance of CHROMagar STEC and CHROMagar STEC O104 (CHROMagar Microbiology, Paris, France) media for the detection of Shiga toxin-producing Escherichia coli (STEC) was assessed with 329 stool specimens collected over 14 months from patients with suspected STEC infections (June 2011 to August 2012). The CHROMagar STEC medium, after an enrichment broth step, allowed the recovery of the STEC strain from 32 of the 39 (82.1%) Shiga toxin-positive stool specimens, whereas the standard procedure involving Drigalski agar allowed the recovery of only three additional STEC strains. The isolates that grew on CHROMagar STEC medium belonged to 15 serotypes, including the prevalent non-sorbitol-fermenting (NSF) O157:H7, O26:H11, and O104:H4 serotypes. The sensitivity, specificity, and positive and negative predictive values for the CHROMagar STEC medium were between 89.1% and 91.4%, 83.7% and 86.7%, 40% and 51.3%, and 98% and 98.8%, respectively, depending on whether or not stx-negative eae-positive E. coli was considered atypical enteropathogenic E. coli (EPEC) or STEC that had lost Shiga toxin genes during infection. In conclusion, the good performance of CHROMagar STEC agar medium, in particular, the high negative predictive value, and its capacity to identify NSF O157:H7 as well as common non-O157 STEC may be useful for clinical bacteriology, public health, and reference laboratories; it could be used in addition to a method targeting Shiga toxins (detection of stx genes by PCR, immunodetection of Shiga toxins in stool specimens, or Vero cell cytotoxicity assay) as an alternative to O157 culture medium. This combined approach should allow rapid visualization of both putative O157 and non-O157 STEC colonies for subsequent characterization, essential for real-time surveillance of STEC infections and investigations of outbreaks. PMID:23284030

  18. The Growth of Steroidobacter agariperforans sp. nov., a Novel Agar-Degrading Bacterium Isolated from Soil, is Enhanced by the Diffusible Metabolites Produced by Bacteria Belonging to Rhizobiales

    PubMed Central

    Sakai, Masao; Hosoda, Akifumi; Ogura, Kenjiro; Ikenaga, Makoto

    2014-01-01

    An agar-degrading bacterium was isolated from soil collected in a vegetable cropping field. The growth of this isolate was enhanced by supplying culture supernatants of bacteria belonging to the order Rhizobiales. Phylogenetic analysis based on 16S rRNA gene sequences indicated the novel bacterium, strain KA5–BT, belonged to the genus Steroidobacter in Gammaproteobacteria, but differed from its closest relative, Steroidobacter denitrificans FST, at the species level with 96.5% similarity. Strain KA5–BT was strictly aerobic, Gram-negative, non-motile, non-spore forming, and had a straight to slightly curved rod shape. Cytochrome oxidase and catalase activities were positive. The strain grew on media containing culture supernatants in a temperature range of 15–37°C and between pH 4.5 and 9.0, with optimal growth occurring at 30°C and pH 6.0–8.0. No growth occurred at 10 or 42°C or at NaCl concentrations more than 3% (w/v). The main cellular fatty acids were iso–C15:0, C16:1ω7c, and iso–C17:1ω9c. The main quinone was ubiquinone-8 and DNA G+C content was 62.9 mol%. In contrast, strain FST was motile, did not grow on the agar plate, and its dominant cellular fatty acids were C15:0 and C17:1ω8c. Based on its phylogenetic and phenotypic properties, strain KA5–BT (JCM 18477T = KCTC 32107T) represents a novel species in genus Steroidobacter, for which the name Steroidobacter agariperforans sp. nov. is proposed. PMID:24621511

  19. Melatonin Protects Human Cells from Clustered DNA Damages, Killing and Acquisition of Soft Agar Growth Induced by X-rays or 970 MeV/n Fe ions

    SciTech Connect

    Das, B.; Sutherland, B.; Bennett, P. V.; Cutter, N. C.; Sutherland, J. C.

    2011-06-01

    We tested the ability of melatonin (N-acetyl-5 methoxytryptamine), a highly effective radical scavenger and human hormone, to protect DNA in solution and in human cells against induction of complex DNA clusters and biological damage induced by low or high linear energy transfer radiation (100 kVp X-rays, 970 MeV/nucleon Fe ions). Plasmid DNA in solution was treated with increasing concentrations of melatonin (0.0-3.5 mM) and were irradiated with X-rays. Human cells (28SC monocytes) were also irradiated with X-rays and Fe ions with and without 2 mM melatonin. Agarose plugs containing genomic DNA were subjected to Contour Clamped Homogeneous Electrophoretic Field (CHEF) followed by imaging and clustered DNA damages were measured by using Number Average length analysis. Transformation experiments on human primary fibroblast cells using soft agar colony assay were carried out which were irradiated with Fe ions with or without 2 mM melatonin. In plasmid DNA in solution, melatonin reduced the induction of single- and double-strand breaks. Pretreatment of human 28SC cells for 24 h before irradiation with 2 mM melatonin reduced the level of X-ray induced double-strand breaks by {approx}50%, of abasic clustered damages about 40%, and of Fe ion-induced double-strand breaks (41% reduction) and abasic clusters (34% reduction). It decreased transformation to soft agar growth of human primary cells by a factor of 10, but reduced killing by Fe ions only by 20-40%. Melatonin's effective reduction of radiation-induced critical DNA damages, cell killing, and striking decrease of transformation suggest that it is an excellent candidate as a countermeasure against radiation exposure, including radiation exposure to astronaut crews in space travel.

  20. Quenching of the antibacterial activity of chlorhexidine and benzalkonium by Letheen broth and Letheen agar in relation to wild-type and envelope mutant strains of gram-negative bacteria.

    PubMed

    el-Falaha, B M; Furr, J R; Russell, A D

    1987-01-01

    Letheen broth and Letheen agar have been investigated for their ability to act as neutralising and recovery media for wild-type and envelope mutants exposed to chlorhexidine diacetate and benzalkonium chloride. At high dilutions, untreated cells of the envelope mutant of Pseudomonas aeruginosa 799/61 were unable to produce colonies on Letheen agar. As a result of various procedures, it was concluded that dilution in Letheen broth and plating in Isosensitest agar was a suitable method for quenching cationic bactericides without harming the test strains, and that the increasing use of Gram-negative bacteria with outer membrane defects means that considerable care may be necessary in selecting media for evaluating bactericidal activity.

  1. Novel single-tube agar-based test system for motility enhancement and immunocapture of Escherichia coli O157:H7 by H7 flagellar antigen-specific antibodies.

    PubMed

    Murinda, Shelton E; Nguyen, Lien T; Ivey, Susan J; Almeida, Raul A; Oliver, Stephen P

    2002-12-01

    This paper describes a novel single-tube agar-based technique for motility enhancement and immunoimmobilization of Escherichia coli O157:H7. Motility indole ornithine medium and agar (0.4%, wt/vol) media containing either nutrient broth, tryptone broth, or tryptic soy broth (TSBA) were evaluated for their abilities to enhance bacterial motility. Twenty-six E. coli strains, including 19 O157:H7 strains, 1 O157:H(-) strain, and 6 generic E. coli strains, were evaluated. Test bacteria were stab inoculated in the center of the agar column, and tubes were incubated at 37 degrees C for 18 to 96 h. Nineteen to 24 of the 26 test strains (73.1 to 92.3%) were motile in the different media. TSBA medium performed best and was employed in subsequent studies of motility enhancement and H7 flagellar immunocapture. H7 flagellar antiserum (30 and 60 micro l) mixed with TSBA was placed as a band (1 ml) in the middle of an agar column separating the top (3-ml) and bottom (3-ml) agar layers. The top agar layer was inoculated with the test bacterial strains. The tubes were incubated at 37 degrees C for 12 to 18 h and for 18 to 96 h. The specificity and sensitivity of the H7 flagellar immunocapture tests were 75 and 100%, respectively. The procedure described is simple and sensitive and could be adapted easily for routine use in laboratories that do not have sophisticated equipment and resources for confirming the presence of H7 flagellar antigens. Accurate and rapid identification of H7 flagellar antigen is critical for the complete characterization of E. coli O157:H7, owing to the immense clinical, public health, and economic significance of this food-borne pathogen.

  2. Detection of Oxacillin Resistance in Staphylococcus aureus Isolated from the Neonatal and Pediatric Units of a Brazilian Teaching Hospital

    PubMed Central

    Pereira, Valéria Cataneli; Martins, André; de Souza Rugolo, Lígia Maria Suppo; de Lourdes Ribeiro de Souza da Cunha, Maria

    2009-01-01

    Objective: To determine, by phenotypic and genotypic methods, oxacillin susceptibility in Staphylococcus aureus strains isolated from pediatric and neonatal intensive care unit patients seen at the University Hospital of the Botucatu School of Medicine. Methods: A total of 100 S. aureus strains isolated from the following materials were studied: 25 blood cultures, 21 secretions, 12 catheters, 3 cannulae and one chest drain from 62 patients in the neonatal unit, and 36 blood cultures, one pleural fluid sample and one peritoneal fluid sample from 38 patients in the pediatric unit. Resistance of the S. aureus isolates to oxacillin was evaluated by the disk diffusion method with oxacillin (1 μg) and cefoxitin (30 μg), agar screening test using Mueller-Hinton agar supplemented with 6 μg/ml oxacillin and 4% NaCl, and detection of the mecA gene by PCR. In addition, the isolates were tested for β-lactamase production using disks impregnated with Nitrocefin and hyperproduction of β-lactamase using amoxicillin (20 μg) and clavulanic acid (10 μg) disks. Results: Among the 100 S. aureus strains included in the study, 18.0% were resistant to oxacillin, with 16.1% MRSA being detected in the neonatal unit and 21.0% in the pediatric unit. The oxacillin (1 μg) and cefoxitin (30 μg) disk diffusion methods presented 94.4% and 100% sensitivity, respectively, and 98.8% specificity. The screening test showed 100% sensitivity and 98.8% specificity. All isolates produced β-lactamase and one of these strains was considered to be a hyperproducer. Conclusions: The 30 μg cefoxitin disk diffusion method presented the best result when compared to the 1 μg oxacillin disk. The sensitivity of the agar screening test was similar to that of the cefoxitin disk diffusion method and higher than that of the oxacillin disk diffusion method. We observed variations in the percentage of oxacillin-resistant isolates during the study period, with a decline over the last years which might be

  3. The acoustic properties, centered on 20 MHZ, of an IEC agar-based tissue-mimicking material and its temperature, frequency and age dependence.

    PubMed

    Brewin, M P; Pike, L C; Rowland, D E; Birch, M J

    2008-08-01

    The purpose of this study was to characterize the ultrasonic properties of agar-based tissue-mimicking materials (TMMs) at ultrasound frequencies centered around 20 MHz. The TMM acoustic properties measured are the amplitude attenuation coefficient alpha (dB cm(-1)MHz(-1)), the speed of sound (ms(-1)) and the backscattered power spectral density (distribution of power per unit frequency normalized to the total received power) characteristics of spectral slope (dB MHz(-1)), y-axis intercept (dB) and reflected power (dB). The acoustic properties are measured over a temperature range of 22 to 37 degrees C. An intercomparison of results between two independent ultrasound measurement laboratories is also presented. A longitudinal study of the acoustic properties over a period of two years is also detailed, and the effect of water immersion on the acoustic properties of TMM is measured. In addition, the physical parameters of mass density rho (kg m(-3)) and specific heat capacity C (J kg(-1) K(-1)) are included. The measurement techniques used were based on the substitution technique using both broadband and narrowband pulses centered on 20 MHz. Both the attenuation coefficient and speed of sound (both group and phase) showed good agreement with the expected values of 0.5 dB cm(-1) MHz(-1) and 1540 ms(-1), respectively, with average values over the three-year period of 0.49 dBcm(-1)MHz1 (SD +/- 0.05) and 1540.9 ms(-1) (SD +/- 8.7). These results also showed agreement between the two independent measurement laboratories. Speed of sound and attenuation coefficient were shown to change with temperature with rates of + 2.1 m s(-1) degrees C(-1) and -0.005 dB cm(-1) MHz(-1) degrees C(-1), respectively. Attenuation changed linearly with frequency at the high frequency range of 17 to 23 MHz, and speed of sound was found to be independent of frequency in this range. The spectral slope of relative backscattered power for the material increased with frequency at typically 1.5 d

  4. Comparison of the recoveries of Escherichia coli and total coliforms from drinking water by the MI agar method and the U.S. Environmental Protection Agency-approved membrane filter method.

    PubMed Central

    Brenner, K P; Rankin, C C; Sivaganesan, M; Scarpino, P V

    1996-01-01

    Drinking water regulations under the Final Coliform Rule require that total coliform-positive drinking water samples be examined for the presence of Escherichia coli or fecal coliforms. The current U.S. Environmental Protection Agency-approved membrane filter (MF) method for E. coli requires two media, an MF transfer, and a total incubation time of 28 h. A newly developed MF method, the MI agar method, containing indoxyl-beta-D-glucuronide and 4-methylumbelliferyl-beta-D-galactopyranoside for the simultaneous detection of E. coli and total coliforms, respectively, by means of their specific enzyme reactions, was compared with the approved method by the use of wastewater-spiked tap water samples. Overall, weighted analysis of variance (significance level, 0.05) showed that the new medium recoveries of total coliforms and E. coli were significantly higher than those of mEndo agar and nutrient agar plus MUG (4-methylumbelliferyl-beta-D-glucuronide), respectively, and the background counts were significantly lower than those of mEndo agar (< 5%). Generally, the tap water source, overall chlorine level, wastewater source, granular activated carbon treatment of the tap water, and method of grouping data by E. coli count for statistical analysis did not affect the performance of the new medium. PMID:8572697

  5. The effect of regions of interest and spectral pre-processing on the detection of non-O157 shiga-toxin producing escherichia coli serogroups on agar media by hyperspectral imaging

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Food borne infection caused by Shiga toxin-producing Escherichia coli (STEC) is a major worldwide health concern. The best known STEC serotype is E. coli O157:H7, which can be easily identified when cultured on sorbitol-MacConkey (SMAC) agar. Recently, six non-O157 STEC serotypes have been found t...

  6. Comparison of rose bengal-chloramphenicol and modified aureomycin-rose bengal-glucose-peptone agar as media for the enumeration of molds and yeasts in water by membrane filtration techniques.

    PubMed

    Albaum, Silva; Masaphy, Segula

    2009-03-01

    The present study compares the suitability of rose bengalchloramphenicol (RBCh) and modified aureomycin-rose bengal glucose-peptone agar for enumerating fungi recovered from diverse water sources using the membrane filtration method. Both mold and yeast colonies were established more rapidly, with more intensified colony colors and higher RBCh counts.

  7. A comparison of serial plate agar dilution, Bauer-Kirby disk diffusion, and the Vitek AutoMicrobic system for the determination of susceptibilities of Klebsiella spp., Enterobacter spp., and Pseudomonas aeruginosa to ten antimicrobial agents.

    PubMed

    Fekete, T; Tumah, H; Woodwell, J; Truant, A; Satishchandran, V; Axelrod, P; Kreter, B

    1994-04-01

    The use of rapid, automated technologies for assessment of antimicrobial susceptibility and determination of minimum inhibitory concentrations has been evolving for over a decade. We compared the Vitek AutoMicrobic system and Bauer-Kirby disk diffusion with the National Committee for Clinical Laboratory Standards methods of serial plate agar dilution for qualitative and quantitative susceptibilities of 301 hospital isolates of Klebsiella spp., Enterobacter spp., and Pseudomonas aeruginosa. Antibiotics tested were aztreonam, cefoperazone, ceftazidime, ceftriaxone, ciprofloxacin, gentamicin, imipenem, piperacillin, ticarcillin-clavulanic acid, and tobramycin. Agar dilution and Bauer-Kirby results were more strongly correlated for all three genera than were the results for agar dilution and Vitek. If agar dilution is presumed to be the "gold standard," Bauer-Kirby disk diffusion had only half the number of false susceptibles as did the Vitek. Thus, the Vitek AutoMicrobic system seems to be somewhat less reliable for both qualitative and quantitative measurement of susceptibility and resistance than is Bauer-Kirby disk diffusion.

  8. Auxofuran, a novel metabolite that stimulates the growth of fly agaric, is produced by the mycorrhiza helper bacterium Streptomyces strain AcH 505.

    PubMed

    Riedlinger, Julia; Schrey, Silvia D; Tarkka, Mika T; Hampp, Rüdiger; Kapur, Manmohan; Fiedler, Hans-Peter

    2006-05-01

    The mycorrhiza helper bacterium Streptomyces strain AcH 505 improves mycelial growth of ectomycorrhizal fungi and formation of ectomycorrhizas between Amanita muscaria and spruce but suppresses the growth of plant-pathogenic fungi, suggesting that it produces both fungal growth-stimulating and -suppressing compounds. The dominant fungal-growth-promoting substance produced by strain AcH 505, auxofuran, was isolated, and its effect on the levels of gene expression of A. muscaria was investigated. Auxofuran and its synthetic analogue 7-dehydroxy-auxofuran were most effective at a concentration of 15 microM, and application of these compounds led to increased lipid metabolism-related gene expression. Cocultivation of strain AcH 505 and A. muscaria stimulated auxofuran production by the streptomycete. The antifungal substances produced by strain AcH 505 were identified as the antibiotics WS-5995 B and C. WS-5995 B completely blocked mycelial growth at a concentration of 60 microM and caused a cell stress-related gene expression response in A. muscaria. Characterization of these compounds provides the foundation for molecular analysis of the fungus-bacterium interaction in the ectomycorrhizal symbiosis between fly agaric and spruce.

  9. The speed of sound and attenuation of an IEC agar-based tissue-mimicking material for high frequency ultrasound applications.

    PubMed

    Sun, Chao; Pye, Stephen D; Browne, Jacinta E; Janeczko, Anna; Ellis, Bill; Butler, Mairead B; Sboros, Vassilis; Thomson, Adrian J W; Brewin, Mark P; Earnshaw, Charles H; Moran, Carmel M

    2012-07-01

    This study characterized the acoustic properties of an International Electromechanical Commission (IEC) agar-based tissue mimicking material (TMM) at ultrasound frequencies in the range 10-47 MHz. A broadband reflection substitution technique was employed using two independent systems at 21°C ± 1°C. Using a commercially available preclinical ultrasound scanner and a scanning acoustic macroscope, the measured speeds of sound were 1547.4 ± 1.4 m∙s(-1) and 1548.0 ± 6.1 m∙s(-1), respectively, and were approximately constant over the frequency range. The measured attenuation (dB∙cm(-1)) was found to vary with frequency f (MHz) as 0.40f + 0.0076f(2). Using this polynomial equation and extrapolating to lower frequencies give values comparable to those published at lower frequencies and can estimate the attenuation of this TMM in the frequency range up to 47 MHz. This characterisation enhances understanding in the use of this TMM as a tissue equivalent material for high frequency ultrasound applications.

  10. Correlation of agar dilution and VITEK2 system for detection of resistance to macrolides, lincosamides and pristinamycin among Staphylococcus aureus and Staphylococcus epidermidis: association with genotypes.

    PubMed

    Bémer, P; Juvin, M-E; Corvec, S; Ros, A; Drugeon, H

    2005-08-01

    The performance of the VITEK2 system was evaluated against the agar dilution reference procedure for testing susceptibility of Staphylococcus aureus and Staphylococcus epidermidis to macrolides, lincosamides and streptogramins (MLS). Eighty clinical isolates were selected according to their resistance phenotype and genotype. Results for erythromycin and clindamycin showed 100% agreement; results for lincomycin showed agreement of 78%, with one very major error and 17 minor errors; and results for pristinamycin showed agreement of 46%, with one major error and 43 minor errors. Most isolates resistant to lincomycin and streptogramin A (L SgAr phenotype) were falsely susceptible to lincomycin, and intermediately-resistant or resistant to pristinamycin, with the VITEK2 system. No resistance gene was detected. Most (80%) isolates resistant constitutively to MLS (MLS(r)BC phenotype) were falsely intermediately-resistant to pristinamycin with the VITEK2 system. The erm(A) gene was more common than erm(C) in MLS(r)BC strains. Resistance to pristinamycin alone (SgA SgB PTr phenotype), or associated with either lincomycin resistance (L SgA SgB PTr phenotype) or constitutive MLS(B) resistance (MLS(BC) SgA PTr phenotype), was well-characterised without discordant results. Resistance to pristinamycin was always associated with resistance to streptogramin A, encoded by the vga(A), vga(B), vgb(A) and vat(A) genes in association with the erm(A) or erm(C) genes.

  11. Genes required for and effects of alginate overproduction induced by growth of Pseudomonas aeruginosa on Pseudomonas isolation agar supplemented with ammonium metavanadate.

    PubMed

    Damron, F Heath; Barbier, Mariette; McKenney, Elizabeth S; Schurr, Michael J; Goldberg, Joanna B

    2013-09-01

    Pseudomonas aeruginosa is an opportunistic pathogen that can adapt to changing environments and can secrete an exopolysaccharide known as alginate as a protection response, resulting in a colony morphology and phenotype referred to as mucoid. However, how P. aeruginosa senses its environment and activates alginate overproduction is not fully understood. Previously, we showed that Pseudomonas isolation agar supplemented with ammonium metavanadate (PIAAMV) induces P. aeruginosa to overproduce alginate. Vanadate is a phosphate mimic and causes protein misfolding by disruption of disulfide bonds. Here we used PIAAMV to characterize the pathways involved in inducible alginate production and tested the global effects of P. aeruginosa growth on PIAAMV by a mutant library screen, by transcriptomics, and in a murine acute virulence model. The PA14 nonredundant mutant library was screened on PIAAMV to identify new genes that are required for the inducible alginate stress response. A functionally diverse set of genes encoding products involved in cell envelope biogenesis, peptidoglycan remodeling, uptake of phosphate and iron, phenazine biosynthesis, and other processes were identified as positive regulators of the mucoid phenotype on PIAAMV. Transcriptome analysis of P. aeruginosa cultures growing in the presence of vanadate showed differential expression of genes involved in virulence, envelope biogenesis, and cell stress pathways. In this study, it was observed that growth on PIAAMV attenuates P. aeruginosa in a mouse pneumonia model. Induction of alginate overproduction occurs as a stress response to protect P. aeruginosa, but it may be possible to modulate and inhibit these pathways based on the new genes identified in this study.

  12. Restoring the selectivity of modified charcoal cefoperazone deoxycholate agar for the isolation of Campylobacter species using tazobactam, a β-lactamase inhibitor.

    PubMed

    Smith, Shaun; Meade, Joseph; McGill, Kevina; Gibbons, James; Bolton, Declan; Whyte, Paul

    2015-10-01

    Extended spectrum β-lactamase (ESBL) producing Escherichia coli have emerged as a contaminant on modified charcoal cefoperazone deoxycholate agar (mCCDA) when attempting to selectively isolate Campylobacter spp. from poultry. E. coli are particularly problematic given their ability to grow under microaerophilic conditions and have been shown to outcompete Campylobacter species making Campylobacter detection or enumeration difficult. This paper recommends a novel method for restoring the selectivity of mCCDA using tazobactam, a β-lactamase inhibitor. The method significantly inhibited ESBL E. coli growth in spiked or naturally contaminated broiler caecal samples (p≤0.01) when compared to conventional mCCDA. This effect was seen at concentrations as low as 1mg/L tazobactam. TmCCDA(1) was found to inhibit up to 8 log10 CFU/mL of ESBL E. coli in mixed pure cultures and 7.5 log10 CFU/mL in caecal samples. Furthermore TmCCDA concentrations up to 10 mg/L had no statistically significant inhibitory effect (p≥0.05) on the recovery of a panel of 27 Campylobacter jejuni and 5 Campylobacter coli isolates when compared to conventional mCCDA. From this study it is suggested that tazobactam, which is more chemically stable than clavulanic acid or sulbactam, is more suitable for restoring the selectivity of mCCDA for the detection or isolation of campylobacters.

  13. Effects of low molecular weight agar and Lactobacillus plantarum on growth performance, immunity, and disease resistance of basa fish (Pangasius bocourti, Sauvage 1880).

    PubMed

    Van Doan, Hien; Doolgindachbaporn, Sompong; Suksri, Amnuaysilpa

    2014-12-01

    This study evaluated effects of low molecular weight agar (LMWA) and Lactobacillus plantarum singly or combined on growth performance, immunity and disease resistance of basa fish (Pangasius bocourti). Two hundred forty fish were divided into four treatments, i.e. 0 g kg(-1) LMWA (Control), 2 g kg(-1) LMWA, 10(8) cfu g(-1)L. plantarum, and 2 g kg(-1) LMWA + 10(8) cfu g(-1)L. plantarum. Following 7, 14 and 28 days of the treatment, specific growth rate (SGR), feed conversion ratio (FCR), serum lysozyme, phagocytosis, respiratory burst and alternative complement activity (ACP) were measured. A Completely Randomized Design with four replications was applied. At the end of the feeding trial, five fish were randomly selected for a challenge test against Aeromonas hydrophila. The results showed that fish fed diet of 2 g kg(-1) LMWA and 10(8) cfu g(-1) of L. plantarum singly or combined significantly enhanced SGR, FCR, serum lysozyme, phagocytosis, respiratory burst, alternative complement activities and post-challenge survival rate of P. bocourti. The results inferred that dietary of LMWA and L. plantarum stimulated growth, immunity and disease resistance of the P. bocourti.

  14. Identification of non-Listeria spp. bacterial isolates yielding a β-D-glucosidase-positive phenotype on Agar Listeria according to Ottaviani and Agosti (ALOA).

    PubMed

    Angelidis, Apostolos S; Kalamaki, Mary S; Georgiadou, Sofia S

    2015-01-16

    Agar Listeria according to Ottaviani and Agosti (ALOA) is the mandatory medium used for the detection and enumeration of Listeria monocytogenes in foods according to the official International Organization for Standardization (ISO) methods. On ALOA, Listeria spp. appear as bluish-green colonies due to the production of β-D-glucosidase, an enzyme that cleaves 5-bromo-4-chloro-3-indolyl-β-D-glucopyranoside, a chromogenic substrate included in the formulation of the medium. The present work reports on bacterial isolates (n=64) from ready-to-eat soft cheeses, which are able to grow on ALOA, forming bluish-green colonies and therefore phenotypically resemble Listeria spp. All isolates were also capable of growing on the selective media PALCAM and RAPID L'mono. The isolates were characterised with biochemical tests including those specified in the ISO standards for the confirmation of Listeria spp. and identified via partial sequencing of their 16S rRNA gene. According to sequencing results the isolates represented 12 different bacterial species or species-groups belonging to seven different genera: Bacillus spp. (B. circulans, B. clausii, B. licheniformis and B. oleronius), Cellulosimicrobium spp. (C. funkei), Enterococcus spp. (E. faecalis, E. faecium/durans), Kocuria spp. (K. kristinae), Marinilactibacillus spp. (M. psychrotolerans), Rothia spp. (R. terrae) and Staphylococcus spp. (S. sciuri and S. saprophyticus subsp. saprophyticus/xylosus). Cellulosimicrobium spp. have never been previously isolated from foods. These results significantly extend the list of bacteria previously known as capable of growing on ALOA as bluish-green colonies and suggest that there may be room for further improvement in the medium's inhibitory properties towards non-Listeria spp., Gram-positive bacteria present in foods.

  15. Bacteria holding times for fecal coliform by mFC agar method and total coliform and Escherichia coli by Colilert®-18 Quanti-Tray® method

    USGS Publications Warehouse

    Aulenbach, Brent T.

    2010-01-01

    Bacteria holding-time experiments of up to 62 h were performed on five surface-water samples from four urban stream sites in the vicinity of Atlanta, GA, USA that had relatively high densities of coliform bacteria (Escherichia coli densities were all well above the US Environmental Protection Agency criterion of 126 colonies (100 ml) − 1 for recreational waters). Holding-time experiments were done for fecal coliform using the membrane filtration modified fecal coliform (mFC) agar method and for total coliform and E. coli using the Colilert®-18 Quanti-Tray® method. The precisions of these analytical methods were quantified. Precisions determined for fecal coliform indicated that the upper bound of the ideal range of counts could reasonably be extended upward and would improve precision. For the Colilert®-18 method, analytical precisions were similar to the theoretical precisions for this method. Fecal and total coliform densities did not change significantly with holding times up to about 27 h. Limited information indicated that fecal coliform densities might be stable for holding times of up to 62 h, whereas total coliform densities might not be stable for holding times greater than about 27 h. E. coli densities were stable for holding times of up to 18 h—a shorter period than indicated from a previous studies. These results should be applicable to non-regulatory monitoring sampling designs for similar urban surface-water sample types.

  16. Detection of Aspergillus-specific antibodies by agar gel double immunodiffusion and IgG ELISA in feline upper respiratory tract aspergillosis.

    PubMed

    Barrs, V R; Ujvari, B; Dhand, N K; Peters, I R; Talbot, J; Johnson, L R; Billen, F; Martin, P; Beatty, J A; Belov, K

    2015-03-01

    Feline upper respiratory tract aspergillosis (URTA) is an emerging infectious disease. The aims of this study were: (1) to assess the diagnostic value of detection of Aspergillus-specific antibodies using an agar gel double immunodiffusion (AGID) assay and an indirect immunoglobulin G (IgG) ELISA; and (2) to determine if an aspergillin derived from mycelia of Aspergillus fumigatus, Aspergillus niger and Aspergillus flavus can be used to detect serum antibodies against cryptic Aspergillus spp. in Aspergillus section Fumigati. Sera from cats with URTA (group 1: n = 21) and two control groups (group 2: cats with other upper respiratory tract diseases, n = 25; group 3: healthy cats and cats with non-respiratory, non-fungal illness, n = 84) were tested. Isolates from cats with URTA comprised A. fumigatus (n = 5), A. flavus (n = 1) and four cryptic species: Aspergillus felis (n = 12), Aspergillus thermomutatus (Neosartorya pseudofischeri, n = 1), Aspergillus lentulus (n = 1) and Aspergillus udagawae (n = 1). Brachycephalic purebred cats were significantly more likely to develop URTA than other breeds (P = 0.013). The sensitivity (Se) of the AGID was 43% and the specificity (Sp) was 100%. At a cut-off value of 6 ELISA units/mL, the Se of the IgG ELISA was 95.2% and the Sp was 92% and 92.9% for groups 2 and 3 cats, respectively. Aspergillus-specific antibodies against all four cryptic species were detected in one or both assays. Assay Se was not associated with species identity. Detection of Aspergillus-specific antibodies by IgG ELISA has high Se and Sp for diagnosis of feline URTA.

  17. Reference characterisation of sound speed and attenuation of the IEC agar-based tissue-mimicking material up to a frequency of 60 MHz.

    PubMed

    Rajagopal, Srinath; Sadhoo, Neelaksh; Zeqiri, Bajram

    2015-01-01

    To support the development of clinical applications of high-frequency ultrasound, appropriate tissue-mimicking materials (TMMs) are required whose acoustic properties have been measured using validated techniques. This paper describes the characterisation of the sound speed (phase velocity) and attenuation coefficient of the International Electrotechnical Commission (IEC) agar-based TMM over the frequency range 1 to 60 MHz. Measurements implemented a broadband through-transmission substitution immersion technique over two overlapping frequency ranges, with co-axially aligned 50 MHz centre-frequency transducers employed for characterisation above 15 MHz. In keeping with usual practice employed within the technical literature, thin acoustic windows (membranes) made of 12-μm-thick Mylar protected the TMM from water damage. Various important sources of uncertainty that could compromise measurement accuracy have been identified and evaluated through a combination of experimental studies and modelling. These include TMM sample thickness, measured both manually and acoustically, and the influence of interfacial losses that, even for thin protective membranes, are significant at the frequencies of interest. In agreement with previous reports, the attenuation coefficient of the IEC TMM exhibited non-linear frequency dependence, particularly above 20 MHz, yielding a value of 0.93 ± 0.04 dB cm(-1) MHz(-1) at 60 MHz, derived at 21 ± 0.5°C. For the first time, phase velocity, measured with an estimated uncertainty of ±3.1 m s(-1), has been found to be dispersive over this extended frequency range, increasing from 1541 m s(-1) at 1 MHz to 1547 m s(-1) at 60 MHz. This work will help standardise acoustic property measurements, and establishes a reference measurement capability for TMMs underpinning clinical applications at elevated frequencies.

  18. Klebsiella pneumonia, a Microorganism that Approves the Non-linear Responses to Antibiotics and Window Theory after Exposure to Wi-Fi 2.4 GHz Electromagnetic Radiofrequency Radiation

    PubMed Central

    Taheri, M.; Mortazavi, S. M. J.; Moradi, M.; Mansouri, Sh.; Nouri, F.; Mortazavi, S. A. R.; Bahmanzadegan, F.

    2015-01-01

    Background Drug resistance is widely believed to be an increasingly serious threat to global public health. We have previously reported that short term exposure of microorganisms to diagnostic ultrasound waves could significantly alter their sensitivity to antibiotics. In our previous studies, Klebsiella pneumoniae showed major differences in the sensitivity to antibiotics in exposed and non-exposed samples. This study was aimed at investigating the alteration of antibiotic resistance of Klebsiella pneumonia, after exposure to Wi-Fi 2.4 GHz electromagnetic radiofrequency radiation. Materials and Methods In this in vitro study, three replicate agar plates were used for each test. The antibiotic susceptibility test was carried out using disc diffusion method on Mueller Hinton agar plates and the inhibition zones in both control and exposed groups were measured. A common Wi-Fi router was used in this study as the radiofrequency exposure source. Irradiated samples were exposed to Wi-Fi radiofrequency radiation for 3, 4.5 and 8 hours. Results Statistically significant variations of sensitivity to antibiotics were found for all studied antibiotics after 4.5 hours of RF exposure, compared to non-exposed bacteria. Interestingly, the mean diameters of the inhibition zones after 3 hours of exposure were less than those exposed for 4.5 hours. Following this rise in the sensitivity to antibiotics, a fall was observed in the bacteria exposed for 8 hours for all studied antibiotics. Conclusion The findings of this study show a statistically significant rise in the sensitivity of Klebsiella pneumoniae to different antibiotics after 4.5 hours of exposure to 2.4 GHz Wi-Fi radiation, followed by a fall after 8 hours of exposure. These observations can be interpreted by the concept of non-linearity in the responses of Klebsiella pneumoniae to different antibiotics after exposure to electromagnetic radiofrequency radiation. As in this study a minimum level of effect was needed for the

  19. Alteration of Bacterial Antibiotic Sensitivity After Short-Term Exposure to Diagnostic Ultrasound

    PubMed Central

    Mortazavi, Seyed Mohammad Javad; Darvish, Leili; Abounajmi, Mohammad; Zarei, Samira; Zare, Tahereh; Taheri, Mohammad; Nematollahi, Samaneh

    2015-01-01

    Background Many pathogenic bacteria show different levels of antibiotic resistance. Furthermore, a lot of hospital-acquired infections are caused by highly resistant or multidrug-resistant Gram-negative bacteria. According to WHO, patients with drug-resistant infections have higher morbidity and mortality. Moreover, patients infected with bacteria that are resistant to antibiotics considerably consume more healthcare resources. Objectives In this study, we explored a physical method of converting drug-resistant bacteria to drug-sensitive ones. Materials and Methods This is an in vitro case-control study, performed at the Ionizing and Non-ionizing Radiation Protection Research Center (INIRPRC), Shiraz University of Medical Sciences (SUMS), Shiraz, Iran in 2014. All experiments were carried out using Gram-negative bacteria Klebsiella pneumonia and E. coli and Gram-positive Staphylococcus aureus and Streptococcus group A, isolated from hospitalized patients. The bacterial strains were obtained from the Persian Type Culture Collection, IROST, Iran (Klebsiella pneumonia PTCC 1290) and Bacteriology Department of Shahid Faghihi Teaching Hospital, Shiraz, Iran (E. coli, Staphylococcus aureus, and Streptococcus group A). The bacteria in culture plates were exposed to diagnostic ultrasound using a MyLab70XVG sonography system for 5 minutes. Then, the bacteria were cultured on Mueller-Hinton agar and incubated at 35°C for 18 hours. Finally, antibiotic susceptibility test was performed and the inhibition zone in both control and exposed groups were measured. Three replicate agar plates were used for each test and the inhibition zones of the plates were recorded. Results Compared with the results obtained from unexposed bacteria, statistically significant variations of sensitivity to antibiotics were found in some strains after short-term exposure. In particular, we found major differences (making antibiotic-resistant bacteria susceptible or vice versa) in the diameters of

  20. [Risk factors for gastrointestinal colonization by ESBL-producing Klebsiella pneumoniae and Escherichia coli in anaesthesiology and reanimation intensive care unit].

    PubMed

    Oğuz Mızrakçı, Serpil; Arda, Bilgin; Erdem, Hüseyin Aytaç; Uyar, Mehmet; Tünger, Alper; Sipahi, Oğuz Reşat; Ulusoy, Sercan

    2013-04-01

    In this study it was aimed to investigate the risk factors for gastrointestinal colonization by extended-spectrum beta-lactamase (ESBL)-producing Klebsiella pneumoniae and Escherichia coli in intensive care unit (ICU) of anaesthesiology and reanimation, Ege University Faculty of Medicine, Izmir, Turkey. This study was performed prospectively on adult patients hospitalized in ICU of anaesthesiology and reanimation and rectal swab cultures were performed in all patients in the first 48 hours of hospitalization and every one week until discharge or death. Samples were transported to the laboratory in Stuart transport medium and were cultured on two EMB agar plates (one including 4 mg/L ceftazidime) and incubated for 48 hours. E.coli and K.pneumoniae isolates were identified by conventional methods. Antibiotic susceptibility tests were performed by disc diffusion method on Mueller Hinton agar and interpreted according to CLSI guidelines. ESBL was confirmed by double disc synergy test. A total of 140 patients (49 female 91 male; age range: 18-83 years, mean age: 56.3 years) were evaluated, and 41 (29.3%) of the patients were found to be colonized with ESBL positive E.coli (n= 39) or K.pneumoniae (n= 2). The mean time for colonization was 11.15 ± 10.91 (range between 2-39) days. Age and gender of the patients and antibiotic consumption before or during the stay in ICU of anaesthesiology and reanimation were not found to be associated with colonization (p> 0.05). However length of ICU of anaesthesiology and reanimation stay in colonized patients was longer than non-colonized patients (27.59 ± 22.52 vs. 17.78 ± 11.74 days; p< 0.05). Infectious episodes developed in 22% (9/41) of the colonized cases and three of the nine strains were isolated from the blood cultures, five from the urine cultures and one from both blood and bronchoalveolar lavage cultures. ESBL-positive E.coli or K.pneumoniae colonization was found as an independent risk factor for the development of

  1. Antimicrobial activity and probable mechanisms of action of medicinal plants of Kenya: Withania somnifera, Warbugia ugandensis, Prunus africana and Plectrunthus barbatus.

    PubMed

    Mwitari, Peter G; Ayeka, Peter A; Ondicho, Joyce; Matu, Esther N; Bii, Christine C

    2013-01-01

    Withania somnifera, Warbugia ugandensis, Prunus africana and Plectrunthus barbatus are used traditionally in Kenya for treatment of microbial infections and cancer. Information on their use is available, but scientific data on their bioactivity, safety and mechanisms of action is still scanty. A study was conducted on the effect of organic extracts of these plants on both bacterial and fungal strains, and their mechanisms of action. Extracts were evaluated through the disc diffusion assay. Bacteria and yeast test strains were cultured on Mueller-Hinton agar and on Sabouraud dextrose agar for the filamentous fungi. A 0.5 McFarland standard suspension was prepared. Sterile paper discs 6 mm in diameter impregnated with 10 µl of the test extract (100 mg/ml) were aseptically placed onto the surface of the inoculated media. Chloramphenicol (30 µg) and fluconazole (25 µg) were used as standards. Discs impregnated with dissolution medium were used as controls. Activity of the extracts was expressed according to zone of inhibition diameter. MIC was determined at 0.78-100 mg/ml. Safety studies were carried using Cell Counting Kit 8 cell proliferation assay protocol. To evaluate extracts mechanisms of action, IEC-6 cells and RT-PCR technique was employed in vitro to evaluate Interleukin 7 cytokine. Investigated plants extracts have both bactericidal and fungicidal activity. W. ugandensis is cytotoxic at IC50<50 µg/ml with MIC values of less than 0.78 mg/ml. Prunus africana shuts down expression of IL 7 mRNA at 50 µg/ml. W. somnifera has the best antimicrobial (1.5625 mg/ml), immunopotentiation (2 times IL 7 mRNA expression) and safety level (IC50>200 µg/ml). Fractions from W. ugandensis and W. somnifera too demonstrated antimicrobial activity. Mechanisms of action can largely be attributed to cytotoxicity, Gene silencing and immunopotentiation. Use of medicinal plants in traditional medicine has been justified and possible mechanisms of action demonstrated. Studies to

  2. Effects of Daytime Exposure to Light from Blue-Enriched Light-Emitting Diodes on the Nighttime Melatonin Amplitude and Circadian Regulation of Rodent Metabolism and Physiology

    PubMed Central

    Dauchy, Robert T; Wren-Dail, Melissa A; Hoffman, Aaron E; Hanifin, John P; Warfield, Benjamin; Brainard, George C; Hill, Steven M; Belancio, Victoria P; Dauchy, Erin M; Blask, David E

    2016-01-01

    Regular cycles of exposure to light and dark control pineal melatonin production and temporally coordinate circadian rhythms of metabolism and physiology in mammals. Previously we demonstrated that the peak circadian amplitude of nocturnal blood melatonin levels of rats were more than 6-fold higher after exposure to cool white fluorescent (CWF) light through blue-tinted (compared with clear) rodent cages. Here, we evaluated the effects of light-phase exposure of rats to white light-emitting diodes (LED), which emit light rich in the blue-appearing portion of the visible spectrum (465–485 nm), compared with standard broad-spectrum CWF light, on melatonin levels during the subsequent dark phase and on plasma measures of metabolism and physiology. Compared with those in male rats under a 12:12-h light:dark cycle in CWF light, peak plasma melatonin levels at the middark phase (time, 2400) in rats under daytime LED light were over 7-fold higher, whereas midlight phase levels (1200) were low in both groups. Food and water intakes, body growth rate, and total fatty acid content of major metabolic tissues were markedly lower, whereas protein content was higher, in the LED group compared with CWF group. Circadian rhythms of arterial plasma levels of total fatty acids, glucose, lactic acid, pO2, pCO2, insulin, leptin, and corticosterone were generally lower in LED-exposed rats. Therefore, daytime exposure of rats to LED light with high blue emissions has a marked positive effect on the circadian regulation of neuroendocrine, metabolic, and physiologic parameters associated with the promotion of animal health and wellbeing and thus may influence scientific outcomes. PMID:27780004

  3. Effects of Daytime Exposure to Light from Blue-Enriched Light-Emitting Diodes on the Nighttime Melatonin Amplitude and Circadian Regulation of Rodent Metabolism and Physiology.

    PubMed

    Dauchy, Robert T; Wren-Dail, Melissa A; Hoffman, Aaron E; Hanifin, John P; Warfield, Benjamin; Brainard, George C; Hill, Steven M; Belancio, Victoria P; Dauchy, Erin M; Blask, David E

    2016-01-01

    Regular cycles of exposure to light and dark control pineal melatonin production and temporally coordinate circadian rhythms of metabolism and physiology in mammals. Previously we demonstrated that the peak circadian amplitude of nocturnal blood melatonin levels of rats were more than 6-fold higher after exposure to cool white fluorescent (CWF) light through blue-tinted (compared with clear) rodent cages. Here, we evaluated the effects of light-phase exposure of rats to white light-emitting diodes (LED), which emit light rich in the blue-appearing portion of the visible spectrum (465-485 nm), compared with standard broadspectrum CWF light, on melatonin levels during the subsequent dark phase and on plasma measures of metabolism and physiology. Compared with those in male rats under a 12:12-h light:dark cycle in CWF light, peak plasma melatonin levels at the middark phase (time, 2400) in rats under daytime LED light were over 7-fold higher, whereas midlight phase levels (1200) were low in both groups. Food and water intakes, body growth rate, and total fatty acid content of major metabolic tissues were markedly lower, whereas protein content was higher, in the LED group compared with CWF group. Circadian rhythms of arterial plasma levels of total fatty acids, glucose, lactic acid, pO2, pCO2, insulin, leptin, and corticosterone were generally lower in LED-exposed rats. Therefore, daytime exposure of rats to LED light with high blue emissions has a marked positive effect on the circadian regulation of neuroendocrine, metabolic, and physiologic parameters associated with the promotion of animal health and wellbeing and thus may influence scientific outcomes.

  4. A comparison study of the EF-18 agar/Hydrophobic Grid Membrane Filter (HGMF) method and the enzyme linked antibody (ELA)/HGMF method to the HPB standard method in the isolation of Salmonella.

    PubMed

    Warburton, D W; Arling, V; Worobec, S; Mackenzie, J; Todd, E C; Lacasse, P; Lamontagne, G; Plante, R; Shaw, S; Bowen, B

    1994-09-01

    As part of a comparative and collaborative study of rapid methods for the detection of Salmonella and the standard Health Protection Branch (HPB) method, six Federal and Provincial Laboratories compared the EF-18 agar/Hydrophobic Grid Membrane Filters (HGMF) method to the standard HPB method. Two Federal Laboratories also compared the enzyme linked antibody (ELA)/HGMF method (which is a further development of the EF-18 agar/HGMF method) to the standard method. During this study the false-negative rates ranged from 0% to 15% for the standard HPB method, from 5.88% to 43.5% for the EF-18 agar/HGMF method, and from 0% to 10.5% for the ELA/HGMF method. The EF-18 agar/HGMF method did not compare well with the standard HPB method due to the number of false-negatives. Problems with this method resulted from the inability to isolate colonies of Salmonella on the HGMF due to the small colony size, abnormal colony coloration, and overgrowth by competitors. The ELA/HGMF method, however, was shown to be comparable to the standard HPB method. The main advantages of this method are that the antibody-staining step is independent of colony coloration and carbohydrate utilization on the plating media; the ability to detect some unusual strains of Salmonella irrespective of their atypical reactions on the media; and the ELA staining can indicate the presence of Salmonella even when the HGMF is overgrown by competitors. Also, cultural confirmation can proceed simultaneously yet independently of the ELA staining procedure. The data presented here indicate that this method is worth further study.

  5. Comparative avoidance behaviour of the earthworm Eisenia fetida towards chloride, nitrate and sulphate salts of Cd, Cu and Zn using filter paper and extruded water agar gels as exposure media.

    PubMed

    Demuynck, Sylvain; Lebel, Aurélie; Grumiaux, Fabien; Pernin, Céline; Leprêtre, Alain; Lemière, Sébastien

    2016-07-01

    We studied the avoidance behaviour of the earthworm Eisenia fetida towards Cd, Cu, and Zn, trace elements (TEs) tested as chloride, nitrate and sulphate salts. Sub adults were exposed individually using dual-cell chambers at 20+2°C in the dark. Recordings were realised at different dates from 2h to 32h. We used filter paper and extruded water agar gel as exposure media to evaluate the contribution of the dermal and the digestive exposure routes on the avoidance reactions. Exposures to Cu or Cd (10mgmetal ionL(-1)) resulted in highly significant avoidance reactions through the exposure duration. Worms avoided Zn poorly and reactions towards Zn salts varied along the exposure. Worm sensitivity towards TEs differed between salts and this could result from differential toxicity or accessibility of these TE salts to earthworms. The anion in itself was not the determinant of the avoidance reactions since exposures to similar concentrations of these anions using calcium salts did not result in significant avoidance worm behaviour. Avoidance responses towards TEs were higher in the case of water agar exposures than in filter paper exposures. Thus, dermal contacts with TE solutions would elicit worm avoidance but signals from receptors located inside the digestive tract could reinforce this behaviour. The use of extruded water agar gels as the substrate allows checking the real sensitivity of earthworm species towards TEs since the TE concentrations leading to significant avoidance reactions were below those reported in the literature when using TE-spiked soils.

  6. Distribution of Streptococcus mutans and Streptococcus sobrinus in Dental Plaque of Indian Pre-School Children Using PCR and SB-20M Agar Medium

    PubMed Central

    Sharma, Arun; Sachdev, Vinod; Chopra, Radhika

    2016-01-01

    Introduction Dental caries is one of the most common infectious diseases affecting the oral cavity. Among the oral bacteria, mutans streptococci have been implicated as major cariogenic bacteria as they can produce high levels of dental caries causing substances such as lactic acid and extracellular polysaccharides. Aim The aim of the study was to detect the presence of Streptococcus mutans and Streptococcus sobrinus in dental plaque by using Polymerase Chain Reaction (PCR) method, quantification of these micro-organisms using Modified Sucrose-Bacitracin (SB-20M) agar medium and to correlate their presence in Caries Active (CA) and Caries Free (CF) pre-school children. Materials and Methods Sixty-eight pre-school children, in the age group of 3-5 years were divided equally into 34 CA and 34 CF children. Dental plaque samples were obtained for detection of these microorganisms by PCR method and quantification was done using SB-20M culture medium. The data was analyzed using statistical software SPSS version 16. For statistical analysis, the frequencies and means of Colony Forming Units (CFU) were used with CI = 95%. For bivariate analysis, Fisher exact test was used at 5% level of significance. The comparison of mean of number of CFU of S. mutans and S. sobrinus was made by Mann Whitney U test and Spearman’s Rho test at 1% level of significance was used for correlation between dmft and CFU in CA group. Results The results showed that S. sobrinus was significantly higher in CA group as compared to CF group whereas S. mutans showed no significant difference. On quantification of these micro-organisms, S. sobrinus was present in significantly higher numbers in CA group as compared to CF group. On correlating the CFU/ml of the micro-organisms with the dmft index, both the micro-organisms showed a positive correlation. Conclusion We conclude that S. mutans and S. sobrinus were detected in higher numbers in CA children as compared to CF children. PCR is a sensitive

  7. CHROMagar Candida Medium for Direct Susceptibility Testing of Yeast from Blood Cultures

    PubMed Central

    Tan, Grace L.; Peterson, Ellena M.

    2005-01-01

    An evaluation was performed on 95 blood cultures positive for Candida spp. to determine the correlation of direct susceptibility testing of fluconazole versus both standardized disk diffusion and MIC methods. For direct testing, an aliquot taken from BD BACTEC Plus and/or BD BACTEC Lytic/10 bottles (Becton Dickinson [BD], Sparks, MD) positive by gram stain for yeast was subcultured to CHROMagar Candida (BD), and a 25-μg fluconazole disk (BD) was placed on the plate. The area of growth inhibition surrounding the disk was measured at 24 and 48 h. In addition, a subculture of the isolate was tested by a microdilution MIC using YeastOne (TREK Diagnostics Systems Inc., OH) and disk diffusion (NCCLS M44-A) using a standardized inoculum plated onto CHROMagar Candida as well as Mueller-Hinton agar to which 2% glucose and 0.5 μg/ml methylene blue dye was added (MH-GMB). The categorical interpretation derived from the MIC was used as the reference to which the disk diffusion results were compared. There were a total of 41 Candida albicans, 23 Candida glabrata, 20 Candida parapsilosis, 9 Candida tropicalis, and 1 each of Candida krusei and Candida lusitaniae tested. At 24 h there was full agreement among the methods for all C. albicans, C. tropicalis, C. lusitaniae, and C. krusei isolates. For the C. parapsilosis isolates at 24 h there was one very major discrepancy using the direct CHROMagar and one major error with the standardized MH-GMB. The majority of the errors were seen at 24 h with the C. glabrata isolates. Of the 23 C. glabrata isolates at 24 h by direct CHROMagar, there were 10 minor and 1 very major error; by MH-GMB there were 12 minor and 2 very major errors; and by standardized CHROMagar Candida there were 13 minor and 2 major errors. There were no very major errors with C. glabrata when all plates were read at 48 h. At 24 h by the direct and standardized CHROMagar the majority of C. glabrata isolates were more resistant, whereas by MH-GMB they were more

  8. Characterizing Vancomycin-Resistant Enterococcus Strains with Various Mechanisms of Daptomycin Resistance Developed in an In Vitro Pharmacokinetic/Pharmacodynamic Model▿

    PubMed Central

    Steed, Molly E.; Vidaillac, Celine; Rose, Warren E.; Winterfield, Patricia; Kaatz, Glenn W.; Rybak, Michael J.

    2011-01-01

    Two daptomycin (DAP) regimens were evaluated in a pharmacokinetic/pharmacodynamic (PK/PD) model, and the mutants recovered were examined for changes in phenotypic characteristics. Three Enterococcus faecium strains (vancomycin-resistant Enterococcus [VRE] ATCC 51559, VRE 12311, and VRE SF 12047) were utilized in a 7-day, 1-compartment in vitro PK/PD model. The simulated dosing regimens were DAP at 6 mg/kg/day (free Cmax [fCmax] = 7.9 μg/ml, half-life [t1/2] = 8 h) and DAP at 10 mg/kg/day (fCmax = 13.17 μg/ml, t1/2 = 8 h). Samples were plated daily on Mueller-Hinton agar containing DAP at 16 μg/ml and 50 mg/liter Ca2+ to assess the emergence of DAP resistance. For each strain, the mutant with the highest DAP MIC was then evaluated for changes in relative surface charge, cell wall thickness, and cytoplasmic membrane depolarization induced by DAP. The initial DAP MICs were 4 μg/ml for all 3 strains. A dose-dependent response and regrowth were observed for DAP 6 mg/kg/day and DAP 10 mg/kg/day against all 3 strains. Mutants of VRE ATCC 51559 (MIC = 128 and 64 μg/ml) and VRE 12311 (MIC = 256 and 32 μg/ml) were recovered from the DAP 6 mg and DAP 10 mg regimen, respectively. For VRE SF 12047, a mutant (MIC = 64 μg/ml) was recovered from the DAP 6 mg model. All mutants displayed an increase in relative surface charge compared to those of their respective parent strains. The DAP-resistant mutants displayed a 43 to 58% increase in cell wall thickness (P < 0.0001), while DAP membrane depolarization decreased by 53 to 65% compared to that of the susceptible strains. VRE with DAP resistance displayed increased surface charge, increased cell wall thickness, and decreased depolarization induced by DAP, consistent with previous observations in Staphylococcus aureus with reduced DAP susceptibility. Further characterization of DAP-resistant VRE is warranted. PMID:21788457

  9. Specific detection and confirmation of Campylobacter jejuni by DNA hybridization and PCR.

    PubMed Central

    Ng, L K; Kingombe, C I; Yan, W; Taylor, D E; Hiratsuka, K; Malik, N; Garcia, M M

    1997-01-01

    Conventional detection and confirmation methods for Campylobacter jejuni are lengthy and tedious. A rapid hybridization protocol in which a 1,475-bp chromogen-labelled DNA probe (pDT1720) and Campylobacter strains filtered and grown on 0.22-micron-pore-size hydrophobic grid membrane filters (HGMFs) are used was developed. Among the environmental and clinical isolates of C. jejuni, Campylobacter coli, Campylobacter jejuni subsp. doylei, Campylobacter lari, and Arcobacter nitrofigilis and a panel of 310 unrelated bacterial strains tested, only C. jejuni and C. jejuni subsp. doylei isolates hybridized with the probe under stringent conditions. The specificity of the probe was confirmed when the protocol was applied to spiked skim milk and chicken rinse samples. Based on the nucleotide sequence of pDT1720, a pair of oligonucleotide primers was designed for PCR amplification of DNA from Campylobacter spp. and other food pathogens grown overnight in selective Mueller-Hinton broth with cefoperazone and growth supplements. All C. jejuni strains tested, including DNase-producing strains and C. jejuni subsp. doylei, produced a specific 402-bp amplicon, as confirmed by restriction and Southern blot analysis. The detection range of the assay was as low as 3 CFU per PCR to as high as 10(5) CFU per PCR for pure cultures. Overnight enrichment of chicken rinse samples spiked initially with as little as approximately 10 CFU/ml produced amplicons after the PCR. No amplicon was detected with any of the other bacterial strains tested or from the chicken background microflora. Since C. jejuni is responsible for 99% of Campylobacter contamination in poultry, PCR and HGMF hybridization were performed on naturally contaminated chicken rinse samples, and the results were compared with the results of conventional cultural isolation on Preston agar. All samples confirmed to be culture positive for C. jejuni were also identified by DNA hybridization and PCR amplification, thus confirming that

  10. Specific detection and confirmation of Campylobacter jejuni by DNA hybridization and PCR.

    PubMed

    Ng, L K; Kingombe, C I; Yan, W; Taylor, D E; Hiratsuka, K; Malik, N; Garcia, M M

    1997-11-01

    Conventional detection and confirmation methods for Campylobacter jejuni are lengthy and tedious. A rapid hybridization protocol in which a 1,475-bp chromogen-labelled DNA probe (pDT1720) and Campylobacter strains filtered and grown on 0.22-micron-pore-size hydrophobic grid membrane filters (HGMFs) are used was developed. Among the environmental and clinical isolates of C. jejuni, Campylobacter coli, Campylobacter jejuni subsp. doylei, Campylobacter lari, and Arcobacter nitrofigilis and a panel of 310 unrelated bacterial strains tested, only C. jejuni and C. jejuni subsp. doylei isolates hybridized with the probe under stringent conditions. The specificity of the probe was confirmed when the protocol was applied to spiked skim milk and chicken rinse samples. Based on the nucleotide sequence of pDT1720, a pair of oligonucleotide primers was designed for PCR amplification of DNA from Campylobacter spp. and other food pathogens grown overnight in selective Mueller-Hinton broth with cefoperazone and growth supplements. All C. jejuni strains tested, including DNase-producing strains and C. jejuni subsp. doylei, produced a specific 402-bp amplicon, as confirmed by restriction and Southern blot analysis. The detection range of the assay was as low as 3 CFU per PCR to as high as 10(5) CFU per PCR for pure cultures. Overnight enrichment of chicken rinse samples spiked initially with as little as approximately 10 CFU/ml produced amplicons after the PCR. No amplicon was detected with any of the other bacterial strains tested or from the chicken background microflora. Since C. jejuni is responsible for 99% of Campylobacter contamination in poultry, PCR and HGMF hybridization were performed on naturally contaminated chicken rinse samples, and the results were compared with the results of conventional cultural isolation on Preston agar. All samples confirmed to be culture positive for C. jejuni were also identified by DNA hybridization and PCR amplification, thus confirming that

  11. [Evaluation of carbapenem inactivation method for the identification of carbapenemase-producing Enterobacteriaceae strains].

    PubMed

    Bayramoğlu, Gülçin; Uluçam, Gülşen; Gençoğlu Özgür, Çiğdem

    2016-07-01

    The rapid and accurate identification of carbapenemases is of crucial importance in terms of infection control. Methods employed in the determination of carbapenemases should be constantly updated in the light of technical advances and newly emerging carbapenemase variants. The aim of this study was to evaluate the performance of the newly developed carbapenem inactivation method (CIM) for the identification of carbapenemases defined in the members of the family Enterobacteriaceae. Enterobacteriaceae isolates with resistance to at least one of the carbapenems (ertapenem, imipenem or meropenem) were included in the study. The study isolates were obtained from various clinical specimens between 2008-2014 and consisted of 56 Enterobacteriaceae strains (12 Escherichia coli, 32 Klebsiella spp., and 12 Enterobacter spp.) in which the presence of the 38 blaOXA-48, 8 blaVIM, 7 blaIMP, 1 blaNDM-1, 1 blaKPC-2 and 1 blaOXA-48+blaVIM genes had been previously determined using the polymerase chain reaction (PCR) and 78 in which no carbapenemase gene were detected. For the performance of the CIM, the test bacteria were suspended in sterile water and then a 10 μg meropenem disc was immersed in the suspension and incubated for 2 hours. This meropenem disc was then removed and subsequently placed on a Mueller-Hinton agar plate inoculated with E. coli ATCC 29522 and incubated at 35°C. The results were assessed after 6 hours and after overnight incubation. Development of an inhibition zone around the meropenem disk was interpreted as the absence of carbapenemase and the lack of an inhibition zone as the presence of carbapenemase. The results of the CIM were obtained after 8 hours. With the CIM, all isolates with previously determined carbapenemase genes were found to be positive and the isolates with no genes revealed to be negative. The sensitivity and specificity of CIM were estimated as 100%. The high sensitivity and specificity, ease of application and interpretation, rapid

  12. CHROMagar Candida medium for direct susceptibility testing of yeast from blood cultures.

    PubMed

    Tan, Grace L; Peterson, Ellena M

    2005-04-01

    An evaluation was performed on 95 blood cultures positive for Candida spp. to determine the correlation of direct susceptibility testing of fluconazole versus both standardized disk diffusion and MIC methods. For direct testing, an aliquot taken from BD BACTEC Plus and/or BD BACTEC Lytic/10 bottles (Becton Dickinson [BD], Sparks, MD) positive by gram stain for yeast was subcultured to CHROMagar Candida (BD), and a 25-microg fluconazole disk (BD) was placed on the plate. The area of growth inhibition surrounding the disk was measured at 24 and 48 h. In addition, a subculture of the isolate was tested by a microdilution MIC using YeastOne (TREK Diagnostics Systems Inc., OH) and disk diffusion (NCCLS M44-A) using a standardized inoculum plated onto CHROMagar Candida as well as Mueller-Hinton agar to which 2% glucose and 0.5 microg/ml methylene blue dye was added (MH-GMB). The categorical interpretation derived from the MIC was used as the reference to which the disk diffusion results were compared. There were a total of 41 Candida albicans, 23 Candida glabrata, 20 Candida parapsilosis, 9 Candida tropicalis, and 1 each of Candida krusei and Candida lusitaniae tested. At 24 h there was full agreement among the methods for all C. albicans, C. tropicalis, C. lusitaniae, and C. krusei isolates. For the C. parapsilosis isolates at 24 h there was one very major discrepancy using the direct CHROMagar and one major error with the standardized MH-GMB. The majority of the errors were seen at 24 h with the C. glabrata isolates. Of the 23 C. glabrata isolates at 24 h by direct CHROMagar, there were 10 minor and 1 very major error; by MH-GMB there were 12 minor and 2 very major errors; and by standardized CHROMagar Candida there were 13 minor and 2 major errors. There were no very major errors with C. glabrata when all plates were read at 48 h. At 24 h by the direct and standardized CHROMagar the majority of C. glabrata isolates were more resistant, whereas by MH-GMB they were more

  13. Standardization of Neisseria meningitidis Serogroup B Colorimetric Serum Bactericida Assay

    PubMed Central

    Rodríguez, Tamara; Lastre, Miriam; Cedré, Barbara; Campo, Judith del; Bracho, Gustavo; Zayas, Caridad; Taboada, Carlos; Díaz, Miriam; Sierra, Gustavo; Pérez, Oliver

    2002-01-01

    The correlate of protection for serogroup B meningococci is not currently known, but for serogroup C it is believed to be the serum bactericidal assay (SBA). The current SBAs are labor intensive and the variations in protocols among different laboratories make interpretation of results difficult. A colorimetric SBA (cSBA), based on the ability of Neisseria meningitidis serogroup B to consume glucose, leading to acid production, was standardized by using group B strain Cu385-83 as the target. The cSBA results were compared to those obtained for a traditional colony-counting microassay (mSBA). Glucose and bromocresol purple pH indicator were added to the medium in order to estimate growth of cSBA target cell survivors through color change. Different variants of the assay parameters were optimized: growth of target cells (Mueller Hinton agar plates), target cell number (100 CFU/per well), and human complement source used at a final concentration of 25%. After the optimization, three other group B strains (H44/76, 490/91, and 511/91) were used as targets for the cSBA. The selection of the assay parameters and the standardization of cSBA were done with 13 sera from vaccinated volunteers. The titers were determined as the higher serum dilution that totally inhibited the bacterial growth marked by the color invariability of the pH indicator. This was detected visually as well as spectrophotometrically and was closely related to a significant difference in the growth of target cell survivors determined using Student’s t test. Intralaboratory reproducibility was ±1 dilution. The correlation between bactericidal median titers and specific immunoglobulin G serum concentration by enzyme immunoassay was high (r = 0.910, P < 0.01). The bactericidal titers generated by the cSBA and the mSBA were nearly identical, and there was a high correlation between the two assays (r = 0.974, P < 0.01). The standardized cSBA allows easy, fast, and efficient evaluation of samples. PMID

  14. Panton-Valentine leukocidin and some exotoxins of Staphylococcus aureus and antimicrobial susceptibility profiles of staphylococci isolated from milks of small ruminants.

    PubMed

    Ünal, Nilgün; Askar, Şinasi; Macun, Hasan Ceyhun; Sakarya, Fatma; Altun, Belgin; Yıldırım, Murat

    2012-03-01

    The aims of this study were to determine the existence of pvl gene, some toxin genes, and mecA gene in Staphylococcus aureus strains isolated from sheep milk and to examine antimicrobial resistance profiles in staphylococci from sheep and goats' milk. The milk samples were collected from 13 different small ruminant farms in Kirikkale province from February to August 2009. A total of 1,604 half-udder milk samples from 857 ewes and 66 half-udder milk samples from 33 goats were collected. Staphylococcus spp. were isolated and identified from the samples. Toxin genes and mecA gene among S. aureus strains were determined by PCR. Antimicrobial susceptibility of staphylococci was examined by the disk diffusion method on Mueller-Hinton agar, and interpreted according to the Clinical Laboratory Standards Institute (CLSI) guidelines. The prevalence of subclinical intramammary infection in both ewes and goats was 5.2%. The most prevalent subclinical mastitis agents were coagulase-negative staphylococci and S. aureus with prevalences 2.8% (n:46) and 1.3% (n = 21), respectively. The prevalence of resistances in isolated Staphylococcus spp. to penicilin G, tetracycline, erythromycin, gentamicin, and enrofloxacin were found as 26.9% (18), 7.5% (5), 6.0% (4), 3.0% (2), and 1.5% (1), respectively. Only 3 of the 21 S. aureus ewe isolates (13.4%) were shown to harbor enterotoxin genes being either seh, sej or sec. However, fourteen (66.6%) of the 21 S. aureus isolates had pvl gene while none of the isolates harbored mecA gene. In conclusion, Staphylococci were shown to be the most prevalent bacteria isolated from subclinical mastitis of ewes and goats and these isolates were susceptible to most of the antibiotics. In addition, S. aureus strains isolated from ewes were harboring few staphylococcal enterotoxin genes. However, Panton-Valentine leukocidin produced by S. aureus could be an important virulence factor and contribute to subclinical mastitis pathogenicity.

  15. An interlaboratory study on efficient detection of Shiga toxin-producing Escherichia coli O26, O103, O111, O121, O145, and O157 in food using real-time PCR assay and chromogenic agar.

    PubMed

    Hara-Kudo, Yukiko; Konishi, Noriko; Ohtsuka, Kayoko; Iwabuchi, Kaori; Kikuchi, Rie; Isobe, Junko; Yamazaki, Takumiko; Suzuki, Fumie; Nagai, Yuhki; Yamada, Hiroko; Tanouchi, Atsuko; Mori, Tetsuya; Nakagawa, Hiroshi; Ueda, Yasufumi; Terajima, Jun

    2016-08-02

    To establish an efficient detection method for Shiga toxin (Stx)-producing Escherichia coli (STEC) O26, O103, O111, O121, O145, and O157 in food, an interlaboratory study using all the serogroups of detection targets was firstly conducted. We employed a series of tests including enrichment, real-time PCR assays, and concentration by immunomagnetic separation, followed by plating onto selective agar media (IMS-plating methods). This study was particularly focused on the efficiencies of real-time PCR assays in detecting stx and O-antigen genes of the six serogroups and of IMS-plating methods onto selective agar media including chromogenic agar. Ground beef and radish sprouts samples were inoculated with the six STEC serogroups either at 4-6CFU/25g (low levels) or at 22-29CFU/25g (high levels). The sensitivity of stx detection in ground beef at both levels of inoculation with all six STEC serogroups was 100%. The sensitivity of stx detection was also 100% in radish sprouts at high levels of inoculation with all six STEC serogroups, and 66.7%-91.7% at low levels of inoculation. The sensitivity of detection of O-antigen genes was 100% in both ground beef and radish sprouts at high inoculation levels, while at low inoculation levels, it was 95.8%-100% in ground beef and 66.7%-91.7% in radish sprouts. The sensitivity of detection with IMS-plating was either the same or lower than those of the real-time PCR assays targeting stx and O-antigen genes. The relationship between the results of IMS-plating methods and Ct values of real-time PCR assays were firstly analyzed in detail. Ct values in most samples that tested negative in the IMS-plating method were higher than the maximum Ct values in samples that tested positive in the IMS-plating method. This study indicates that all six STEC serogroups in food contaminated with more than 29CFU/25g were detected by real-time PCR assays targeting stx and O-antigen genes and IMS-plating onto selective agar media. Therefore, screening

  16. Wide variability in Pseudomonas aeruginosa aminoglycoside results among seven susceptibility testing procedures.

    PubMed Central

    Staneck, J L; Glenn, S; DiPersio, J R; Leist, P A

    1989-01-01

    Seven commonly used antimicrobial susceptibility testing methods were used to test the susceptibility of 150 isolates of Pseudomonas aeruginosa against gentamicin, tobramycin, amikacin, carbenicillin, and piperacillin. Results were compared with respect to the susceptibility characteristics of the population of isolates as defined by each method. Conventional methods included agar disk diffusion and agar dilution, carried out in accordance with current recommendations of the National Committee for Clinical Laboratory Standards, as well as broth microdilution testing with cation-supplemented Mueller-Hinton broth (CSMHB). Methods in which instrumentation was used for result determination included the Autobac I, Avantage, Sensititre Autoreader (using a breakpoint panel at 18 h of incubation), and Vitek (AMS-240, using the GNS susceptibility card). When necessary for comparison, MIC data were converted to categorical interpretations (susceptible, intermediate, and resistant). With respect to gentamicin, no significant differences were noted among the results of disk diffusion, broth microdilution, Sensititre Auto breakpoint, or Vitek methods which characterized 60 to 67% of isolates as susceptible, 16 to 22% as intermediate, and 13 to 17% as resistant. In contrast, agar dilution, Autobac, and Avantage, although yielding gentamicin results similar to those of one another, were each significantly different in result reporting from the other four methods above for gentamicin results, and they characterized the Pseudomonas population largely as susceptible (88 to 97%), with 0 to 6% intermediate and only 3% to 6% resistant. More isolates were characterized as being resistant to gentamicin in the Avantage test if an assay broth supplemented with increased amounts of calcium was used. Cation impregnation of Autobac disks did not appreciably change Autobac results. The geometric mean MIC of gentamicin was 4 micrograms/ml lower in the agar dilution method than in the CSMHB

  17. Evaluation of risk factors in patients with vulvovaginal candidiasis and the value of chromID Candida agar versus CHROMagar Candida for recovery and presumptive identification of vaginal yeast species.

    PubMed

    Guzel, Ahmet Bariş; Ilkit, Macit; Akar, Tuba; Burgut, Refik; Demir, S Cansun

    2011-01-01

    Vulvovaginal candidiasis (VVC), particularly the recurrent form, remains an intractable problem for clinicians, microbiologists, and patients. It is essential to confirm the clinical diagnosis by mycological methods and avoid empirical therapy. The recovery of yeast in fungal culture, such as on Sabouraud dextrose agar, remains the gold standard for diagnosis. In this investigation, we examined 474 participants, including 122 (25.7%) with acute VVC cases, 249 (52.5%) who had recurrent VVC (RVVC) cases, and 103 (21.7%) healthy controls. We also administered a questionnaire to obtain information on patient lifestyle and medical, gynecological, and sexual history. In addition, we compared the performance of chromID Candida agar (CAN2) to CHROMagar Candida (CAC) and Sabouraud dextrose agar with gentamicin and chloramphenicol (SGC2). The yeasts were identified by conventional methods including the germ tube test, microscopic morphology on cornmeal-Tween 80 agar, and the commercial API 20C AUX system. We detected yeasts in 60 of 122 (49.2%) patients with acute VVC cases, 110 of 249 (44.2%) with RVVC cases, and in 35 of 103 (34%) healthy controls (P = 0.07). A total of 205 samples were found to be positive for fungi (43.2%), of which 176 (85.9%) were monofungal, and 29 (14.1%) were polyfungal. In addition, 198 of these samples (96.6%) were positive on CAN2, 195 (95.1%) on CAC, 189 (92.2%) on SGC2, and 183 (89.3%) samples on all three (P = 0.17). The 234 yeast isolates recovered were C. albicans (n = 118), C. glabrata (n = 82), C. kefyr (n = 11), C. krusei (n = 9), C. lipolytica (n = 3), C. colliculosa (n = 2), C. parapsilosis (n = 2), C. pelliculosa (n = 2), C. tropicalis (n = 2), and other species of Candida (n = 3). Of the 29 polyfungal populations, 28 (96.6%) were detected in CAN2, 25 in (86.2%) CAC, and 25 (86.2%) on both (P = 0.35). Notably, we detected the high predominance of C. albicans+C. glabrata (86.2%) in polyfungal populations. Briefly, the detection of C

  18. New methods for isolation of keratolytic bacteria inducing intractable hoof wall cavity (Gidoh) in a horse; double screening procedures of the horn powder agar-translucency test and horn zymography

    PubMed Central

    KUWANO, Atsutoshi; NIWA, Hidekazu; ARAI, Katsuhiko

    2017-01-01

    ABSTRACT To establish a new system to isolate keratolytic bacteria from the hoof wall cavity (Gidoh) of a racehorse, we invented the horn powder agar-translucency (HoPAT) test and horn zymography (HZ). Using routine bacteriological techniques and these methods, we isolated five strains of keratolytic soil bacteria, which were then identified by means of 16S ribosomal RNA (rRNA) gene sequencing analysis. The findings from the study on the horse suggested that Brevibacterium luteolum played the main role in the local fragility of the hoof, eventually forming a Gidoh in coordination with four other strains of keratolytic bacteria. The double screening procedures of the HoPAT test and HZ were useful and easy techniques for isolating the keratolytic bacteria from the horn lesions.

  19. Evaluation of Trans-Vag Broth, Colistin-Nalidixic Agar, and CHROMagar StrepB for Detection of Group B Streptococcus in Vaginal and Rectal Swabs from Pregnant Women in South Africa

    PubMed Central

    Kwatra, Gaurav; Madhi, Shabir A.; Cutland, Clare L.; Buchmann, Eckhart J.

    2013-01-01

    Maternal vaginal colonization with group B streptococcus (GBS) is a major risk factor for invasive GBS infection in newborns. The CDC-recommended method for detecting GBS colonization is to culture vaginal and rectal swabs in a selective broth followed by subculture on blood agar or a selective medium. A high incidence of antimicrobial resistance in the fecal microflora can compromise the recovery of GBS from the selective broth. Here, we compared CHROMagar StrepB (CA), Columbia colistin-nalidixic agar (CNA), and Trans-Vag selective broth enrichment for the isolation of GBS from 130 vaginal and 130 rectal swabs from pregnant women. The swabs were randomized for plating first on either CA or CNA, and they then were inoculated in Trans-Vag broth. GBS was cultured from 37.7% of the vaginal swabs and 33.1% of the rectal swabs. There were no differences in the detection rates for the vaginal swabs between CA (31.5%), CNA (26.2%), and the selective broth (30.0%). The sensitivities in relation to a composite score were 83.7%, 69.4%, and 79.6%, respectively. However, recovery of GBS from the rectal swabs was significantly higher from CA (29.2%; P < 0.0001) and CNA (23.8%; P = 0.002) than from the selective broth (9.2%). The sensitivities were 88.4%, 72.1%, and 27.9%, respectively. The order of plating on the solid medium was significant (P = 0.003), with GBS detection rates of 30.8% and 24.6% when swabs were plated first and second, respectively. These findings show that a selective broth is not suitable for the recovery of GBS from rectal swabs in settings such as ours, due to masking of the GBS colonies by persistent microflora. PMID:23698527

  20. Methicillin-Resistant Staphylococcus aureus (MRSA) Detection: Comparison of Two Molecular Methods (IDI-MRSA PCR Assay and GenoType MRSA Direct PCR Assay) with Three Selective MRSA Agars (MRSA ID, MRSASelect, and CHROMagar MRSA) for Use with Infection-Control Swabs▿

    PubMed Central

    van Hal, S. J.; Stark, D.; Lockwood, B.; Marriott, D.; Harkness, J.

    2007-01-01

    Methicillin-resistant Staphylococcus aureus (MRSA) is an increasing problem. Rapid detection of MRSA-colonized patients has the potential to limit spread of the organism. We evaluated the sensitivities and specificities of MRSA detection by two molecular methods (IDI-MRSA PCR assay and GenoType MRSA Direct PCR assay) and three selective MRSA agars (MRSA ID, MRSASelect, and CHROMagar MRSA), using 205 (101 nasal, 52 groin, and 52 axillary samples) samples from consecutive known MRSA-infected and/or -colonized patients. All detection methods had higher MRSA detection rates for nasal swabs than for axillary and groin swabs. Detection of MRSA by IDI-MRSA was the most sensitive method, independent of the site (94% for nasal samples, 80% for nonnasal samples, and 90% overall). The sensitivities of the GenoType MRSA Direct assay and the MRSA ID, MRSASelect, and CHROMagar MRSA agars with nasal swabs were 70%, 72%, 68%, and 75%, respectively. All detection methods had high specificities (95 to 99%), independent of the swab site. Extended incubation for a further 24 h with selective MRSA agars increased the detection of MRSA, with a corresponding decline in specificity secondary to a significant increase in false-positive results. There was a noticeable difference in test performance of the GenoType MRSA Direct assay in detection of MRSA (28/38 samples [74%]) compared with detection of nonmultiresistant MRSA (17/31 samples [55%]) (susceptible to two or more non-β-lactam antibiotics). This was not observed with selective MRSA agar plates or IDI-MRSA. Although it is more expensive, in addition to rapid turnaround times of 2 to 4 h, IDI-MRSA offers greater detection of MRSA colonization, independent of the swab site, than do conventional selective agars and GenoType MRSA Direct. PMID:17537949

  1. Production of pseudorabies virus recombinant glycoprotein B and its use in an agar gel immunodiffusion (AGID) test for detection of antibodies with sensitivity and specificity equal to the virus neutralization assay.

    PubMed

    Serena, María Soledad; Geisler, Christoph; Metz, Germán Ernesto; Mórtola, Eduardo Carlos; Echeverría, María Gabriela

    2016-04-01

    Pseudorabies virus (PrV) causes Aujeszky's disease (AD), which affects mainly swine, but also cattle, sheep, and wild animals, resulting in substantial economic losses due to animal mortality and lost productivity worldwide. To combat PrV, eradication programs using PrV strains lacking the gene encoding glycoprotein E (gE) are ongoing in several countries. These eradication programs have generated a currently unmet demand for affordable, easy-to-use, and sensitive tests that can detect PrV infection in pigs infected with either wild-type virus or vaccine strain (gE-deleted) virus. To meet this demand, we used the baculovirus-insect cell system to produce recombinant glycoprotein B (gB) as antigen for an immune assay. The high GC-content (70% average) of the gB gene from the Argentinian PrV CL15 strain necessitated the use of betaine as a PCR enhancer to amplify the extracellular domain. Recombinant gB was expressed at high levels and reacted strongly with sera from PrV infected pigs. We used the recombinant gB to develop an agar gel immunodiffusion (AGID) test for detection of PrV antibodies. Compared to the gold standard virus neutralization (VN) assay, the AGID sensitivity and specificity were 95% and 96.6% respectively. Thus, recombinant gB produced in the baculovirus-insect cell system is a viable source of antigen for the detection of PrV antibodies in AGID tests. Considering its relatively lower cost, simplicity of use and result interpretation, our AGID is a valuable alternative tool to the VN assay.

  2. Comparison of MRSASelect Agar, CHROMagar Methicillin-Resistant Staphylococcus aureus (MRSA) Medium, and Xpert MRSA PCR for Detection of MRSA in Nares: Diagnostic Accuracy for Surveillance Samples with Various Bacterial Densities ▿

    PubMed Central

    Wolk, D. M.; Marx, J. L.; Dominguez, L.; Driscoll, D.; Schifman, R. B.

    2009-01-01

    Rapid laboratory methods provide optimal support for active surveillance efforts to screen for methicillin-resistant Staphylococcus aureus (MRSA). Most laboratories struggle to determine the optimal use of resources, considering options to balance cost, speed, and diagnostic accuracy. To assess the performance of common methods, the first comparison of MRSASelect agar (MS) and CHROMagar MRSA (CA), with and without broth enrichment followed by a 24-h subculture to MS, was performed. Results were compared to those of the Xpert MRSA assay. For direct culture methods, the agreement between MS and CA was 98.8%. At 18 h, direct MS identified 93% of all positive samples from direct culture and 84% of those identified by the Xpert MRSA. For Trypticase soy broth-enriched MS culture, incubated overnight and then subcultured for an additional 24 h, the agreement with Xpert MRSA was 96%. The agreement between direct MS and Xpert MRSA was 100% when semiquantitative culture revealed a bacterial density of 2+ or greater; however, discrepancies between culture and Xpert MRSA arose for MRSA bacterial densities of 1+ or less, indicating low density as a common cause of false-negative culture results. Since 1+ or less was established as the most common MRSA carrier state, broth enrichment or PCR may be critical for the identification of all MRSA carriers who may be reservoirs for transmission. In this active-surveillance convenience sample, the use of broth enrichment followed by subculture to MS offered a low-cost but sensitive method for MRSA screening, with performance similar to that of Xpert MRSA PCR. PMID:19828738

  3. Comparison of MRSASelect Agar, CHROMagar Methicillin-Resistant Staphylococcus aureus (MRSA) Medium, and Xpert MRSA PCR for detection of MRSA in Nares: diagnostic accuracy for surveillance samples with various bacterial densities.

    PubMed

    Wolk, D M; Marx, J L; Dominguez, L; Driscoll, D; Schifman, R B

    2009-12-01

    Rapid laboratory methods provide optimal support for active surveillance efforts to screen for methicillin-resistant Staphylococcus aureus (MRSA). Most laboratories struggle to determine the optimal use of resources, considering options to balance cost, speed, and diagnostic accuracy. To assess the performance of common methods, the first comparison of MRSASelect agar (MS) and CHROMagar MRSA (CA), with and without broth enrichment followed by a 24-h subculture to MS, was performed. Results were compared to those of the Xpert MRSA assay. For direct culture methods, the agreement between MS and CA was 98.8%. At 18 h, direct MS identified 93% of all positive samples from direct culture and 84% of those identified by the Xpert MRSA. For Trypticase soy broth-enriched MS culture, incubated overnight and then subcultured for an additional 24 h, the agreement with Xpert MRSA was 96%. The agreement between direct MS and Xpert MRSA was 100% when semiquantitative culture revealed a bacterial density of 2+ or greater; however, discrepancies between culture and Xpert MRSA arose for MRSA bacterial densities of 1+ or less, indicating low density as a common cause of false-negative culture results. Since 1+ or less was established as the most common MRSA carrier state, broth enrichment or PCR may be critical for the identification of all MRSA carriers who may be reservoirs for transmission. In this active-surveillance convenience sample, the use of broth enrichment followed by subculture to MS offered a low-cost but sensitive method for MRSA screening, with performance similar to that of Xpert MRSA PCR.

  4. Early detection of oxacillin-resistant staphylococcal strains with hypertonic broth diluent for microdilution panels.

    PubMed Central

    Dillon, L K; Howe, S E

    1984-01-01

    A total of 292 coagulase-positive and 111 coagulase-negative staphylococcal strains were tested in microdilution MIC panels containing 16 to 0.13 microgram of oxacillin per ml diluted in cation-supplemented Mueller-Hinton broth with and without an additional 2% NaCl. All strains were tested using the stationary-phase inoculum procedure with an incubation temperature of 35 degrees C. Test results were recorded after 16 to 20 h of incubation; staphylococcal strains susceptible to oxacillin (less than or equal to 2 micrograms/ml) were reincubated for 20 to 24 h, and endpoints were determined again. Oxacillin resistance was found in 27 (9%) of the 292 coagulase-positive strains and 39 (35%) of the 111 coagulase-negative strains. Of these resistant strains, 5 (19%) of the 27 coagulase-positive strains and 13 (33%) of the 39 coagulase-negative strains were detected 24 h earlier in cation-supplemented Mueller-Hinton broth with 2% NaCl than in cation-supplemented Mueller-Hinton broth without the additional NaCl. However, 9 (33%) of the 27 resistant coagulase-positive strains and 10 (26%) of the 39 resistant coagulase-negative strains were detected only after an additional 24 h of incubation. Oxacillin MICs for the 265 coagulase-positive susceptible strains and 72 coagulase-negative susceptible strains were not affected by the additional 2% NaCl. These results support the utility of addi