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Sample records for disc susceptibility testing

  1. BSAC standardized disc susceptibility testing method (version 11).

    PubMed

    Howe, R A; Andrews, J M

    2012-12-01

    This article highlights key amendments incorporated into version 11 of the BSAC standardized disc susceptibility testing method, available as Supplementary data at JAC Online (http://jac.oxfordjournals.org/) and on the BSAC web site (http://bsac.org.uk/susceptibility/guidelines-standardized-disc-susceptibility-testing-method/). The basic disc susceptibility testing method remains unchanged, but there have been a number of alterations to the interpretive criteria for certain organism/drug combinations due to continuing harmonization with the EUCAST MIC breakpoints and constant efforts to improve the reliability and clinical applicability of the guidance.

  2. 21 CFR 866.1620 - Antimicrobial susceptibility test disc.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Antimicrobial susceptibility test disc. 866.1620 Section 866.1620 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Diagnostic Devices § 866.1620...

  3. 21 CFR 866.1620 - Antimicrobial susceptibility test disc.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Antimicrobial susceptibility test disc. 866.1620 Section 866.1620 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Diagnostic Devices § 866.1620...

  4. 21 CFR 866.1620 - Antimicrobial susceptibility test disc.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Antimicrobial susceptibility test disc. 866.1620 Section 866.1620 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Diagnostic Devices § 866.1620...

  5. 21 CFR 866.1620 - Antimicrobial susceptibility test disc.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Antimicrobial susceptibility test disc. 866.1620 Section 866.1620 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Diagnostic Devices § 866.1620...

  6. 21 CFR 866.1620 - Antimicrobial susceptibility test disc.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Antimicrobial susceptibility test disc. 866.1620 Section 866.1620 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... to determine the antimicrobial agent of choice in the treatment of bacterial diseases....

  7. BSAC standardized disc susceptibility testing method (version 10).

    PubMed

    Andrews, J M; Howe, R A

    2011-12-01

    The BSAC standardized disc susceptibility testing method remains unchanged, but there are considerable changes to the interpretative criteria due to continuing harmonization with the European Committee on Antimicrobial Susceptibility Testing (EUCAST) MIC breakpoints. There are a number of agents for which interpretative criteria have been removed. These MIC and/or zone diameter breakpoints will be published on the BSAC web site as a 'Legacy' table; they may be used for research or comparative purposes, but are not recommended for clinical management. Notably, testing of staphylococci for susceptibility to glycopeptides by disc diffusion has been removed because this method has been found to be unreliable, particularly for the detection of low-level resistance; low-level vancomycin resistance in staphylococci is increasingly deemed to be of clinical relevance. The tables for anaerobes have been expanded to include MIC breakpoints that have been determined by EUCAST. There are currently no zone diameter breakpoints for these organisms and an MIC method is recommended if susceptibility testing is required.

  8. BSAC standardized disc susceptibility testing method (version 8).

    PubMed

    Andrews, J M

    2009-09-01

    azithromycin, clarithromycin, erythromycin and telithromycin (Table 15); clarithromycin and erythromycin MIC and zone diameter BPs for Moraxella catarrhalis (Table 16); azithromycin MIC BPs for Neisseria gonorrhoeae (Table 17); chloramphenicol and rifampicin MIC BPs for Neisseria meningitidis (Table 18); azithromycin MIC BPs for Haemophilus influenzae (Table 19); MIC BPs for metronidazole for Bacteroides fragilis, Bacteroides thetaiotaomicron and Clostridium perfringens (Tables 23-25, respectively); susceptibility testing of Listeria spp. (Appendix 3); the acceptable range for ATCC 25923 to a 10 microg tobramycin disc (Table 26).

  9. BSAC standardized disc susceptibility testing method (version 7).

    PubMed

    Andrews, J M

    2008-08-01

    The changes that have been made to the previous version of the recommendations (version 6) are as follows: medium and incubation condition for testing Acinetobacter spp. (Tables 1 and 6); use of cefoxitin as an indicator antibiotic for detecting methicillin/oxacillin/cefoxitin resistance in coagulase-negative staphylococci (Tables 1, 6 and 11); MIC breakpoint for co-trimoxazole based on the trimethoprim concentration in a 1:19 combination with sulfamethoxazole (Tables 7, 10, 11, 12, 15, 16 and 19); advice on the use of azithromycin for the treatment of infections with Salmonella typhi (footnote to Table 7); amendment to the recommendation for cefuroxime for the treatment of infections with Proteus mirabilis (footnote Table 7); MIC and zone diameter breakpoints for Stenotrophomonas maltophilia only (Table 10); MIC breakpoints for daptomycin (Tables 11 and 15); clarification for staphylococci that the neomycin zone diameter breakpoints are for topical use only and differentiate the isolates outside the 'wild-type' population in Table 11; clarification for beta-haemolytic streptococci that the linezolid zone diameter breakpoints relate to an MIC breakpoint of 2 mg/L as no data for the intermediate category are currently available (Table 15); clarification that strains with reduced susceptibility to fluoroquinolones give no zone of inhibition with a 30 microg nalidixic acid disc (Tables 16 and 21); erythromycin is no longer used for therapy of Neisseria gonorrhoeae, but may be tested for epidemiological purposes (Table 17); clarification that the ciprofloxacin zone diameter breakpoint for Neisseria meningitidis relates to the MIC breakpoint of 0.03 mg/L as no data for the intermediate category are currently available; clarification that the ciprofloxacin zone diameter breakpoints for Campylobacter spp. relate to an MIC breakpoint of 0.5 mg/L as no data for the intermediate category are currently available; clarification that for ciprofloxacin and vancomycin zone

  10. Rifaximin disc diffusion test for in vitro susceptibility testing of Clostridium difficile.

    PubMed

    Huhulescu, Steliana; Sagel, Ulrich; Fiedler, Anita; Pecavar, Verena; Blaschitz, Marion; Wewalka, Guenther; Allerberger, Franz; Indra, Alexander

    2011-08-01

    Rifaximin is a rifampicin derivative, poorly absorbed by the gastro-intestinal tract. We studied the in vitro susceptibility to rifamixin of 1082 Clostridium difficile isolates; among these, 184 isolates from a strain collection were tested by an in-house rifaximin disc (40 µg) diffusion test, by an in-house rifaximin broth microdilution test, by rifampicin Etest and by rpoB gene sequencing. In the absence of respective CLSI or EUCAST MIC breakpoints for rifaximin and rifampicin against C. difficile we chose MIC ≥32 µg ml(-1) as criterion for reduced in vitro susceptibility. To further validate the disc diffusion test 898 consecutive clinical isolates were analysed using the disc diffusion test, the Etest and rpoB gene sequence analysis for all resistant strains. Rifaximin broth microdilution tests of the 184 reference strains yielded rifaximin MICs ranging from 0.001 (n = 1) to ≥1024 µg ml(-1) (n = 61); 62 isolates showed a reduced susceptibility (MIC ≥32 µg ml(-1)). All of these 62 strains showed rpoB gene mutations producing amino acid substitutions; the rifampicin- and rifaximin-susceptible strains showed either a wild-type sequence or silent amino acid substitutions (19 strains). For 11 arbitrarily chosen isolates with rifaximin MICs of >1024 µg ml(-1), rifaximin end-point MICs were determined by broth dilution: 4096 µg ml(-1) (n = 2), 8192 µg ml(-1) (n = 6), 16,384 µg ml(-1) (n = 2) and 32,678 µg ml(-1) (n = 1). Rifampicin Etests on the 184 C. difficile reference strains yielded MICs ranging from ≤0.002 (n = 117) to ≥32 µg ml(-1) (n = 59). Using a 38 mm inhibition zone as breakpoint for reduced susceptibility the use of rifaximin disc diffusion yielded 59 results correlating with those obtained by use of rifaximin broth microdilution in 98.4 % of the 184 strains tested. Rifampicin Etests performed on the 898 clinical isolates revealed that 67 isolates had MICs of ≥32 µg ml(-1). There were no discordant

  11. Susceptibility Testing

    MedlinePlus

    ... Also known as: Sensitivity Testing; Drug Resistance Testing; Culture and Sensitivity; C & S; Antimicrobial Susceptibility Formal name: Bacterial and Fungal Susceptibility Testing Related tests: Urine Culture ; Blood Culture ; Bacterial Wound Culture ; AFB Testing ; MRSA ; ...

  12. 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.

  13. Comparative assessment of CDS, CLSI disc diffusion and Etest techniques for antimicrobial susceptibility testing of Neisseria gonorrhoeae: a 6-year study

    PubMed Central

    Singh, Vikram; Kakran, Monika; Ramesh, V

    2012-01-01

    Background A variety of techniques are available for antimicrobial susceptibility testing of Neisseria gonorrhoeae. Objective The aim of this study was to find a cost-effective, reliable and easily applicable microbiological method to detect antimicrobial susceptibilities of N. gonorrhoeae in resource-poor countries. Design Prospective study. Setting Male and female STD clinic of Regional STD Teaching, Training and Research Centre, New Delhi, India. Participants N. gonorrhoeae isolates from all male and female patients presenting with acute gonococcal urethritis and cervical discharge. Material and methods A total of 295 consecutive N. gonorrhoeae isolates during 2005–2010 was used to compare the Clinical and Laboratory Standards Institute (CLSI) and CDS disc diffusion technique with Etest by performing antimicrobial susceptibility testing in parallel for penicillin, tetracycline, ceftriaxone, ciprofloxacin and spectinomycin. WHO reference strains were used as controls. Results CDS disc diffusion zones of inhibition showed that complete percentage agreement for penicillin, ciprofloxacin and tetracycline was high with their analogous Etest minimal inhibitory concentrations in comparison to CLSI disc diffusion technique, that is, 91.5%, 92.9% and 99.3% versus 87.5%, 88.5% and 74.9%, respectively. CDS results had less number of major and minor category discrepancies in comparison to CLSI and CDS method showed excellent correlation coefficient (r=1) with Etest for all five antimicrobial agents tested in comparison to CLSI (r=0.92). It was very poor (r=0.61) by CLSI method for tetracycline. The correlation coefficients between the two methods and the Etest were identical if tetracycline was removed from the CLSI analysis. Conclusions The CDS technique is an attractive alternative for N. gonorrhoeae susceptibility testing and is recommended for monitoring the antimicrobial susceptibility in less developed and resource-poor settings to facilitate enhanced antimicrobial

  14. Evaluation of the mastascanelite image analysis system for measuring zones of inhibition in disc diffusion susceptibility tests.

    PubMed

    Clarke, R E H; Winstanley, T G; Ridgway, E J

    2003-01-01

    In this evaluation a mastascanelite image analysis system is compared with manual measurement of disc diffusion inhibition zones. Data for 213 diverse organisms and a total of 1679 organism/antibiotic combinations gave an overall correlation coefficient of 0.988. The mean difference between readings was +0.425 mm, with 95% confidence limits of +/-2.94 mm, and the majority of scanned zones (97.51%) fell within +/-3 mm of the manual measurement. The mastascanelite system forms part of a laboratory suite and was found to be objective, accurate and rapid, reading and interpreting each plate in less than a second. Interfacing to the laboratory computer system facilitated data handling and performance control.

  15. Instrumentation in antimicrobial susceptibility testing.

    PubMed

    Felmingham, D; Brown, D F

    2001-07-01

    Studies in the 1960s demonstrated the problems of variability in susceptibility testing methods, especially those affecting the performance of disc diffusion procedures. These studies made apparent the need for standardization and resulted in more clearly defined performance limits for growth medium, incubation conditions, inoculum concentration, disc content for diffusion methods, the setting of interpretative MIC breakpoints and the establishment of quality control parameters. More recently, there has been a growing interest in the use of instrumentation for reading disc diffusion tests and the endpoints of agar or broth dilution MIC determinations. Instrumentation ranges in complexity from the simple optical reading of zones of inhibition or growth endpoints, requiring operator interpretation, to more sophisticated devices for reading, recording and 'expert system' analysis of results with interfacing of instruments to laboratory information management systems. Some of the more developed systems are fully automated and can also identify the organisms tested. The pressure to reduce labour costs and provide results earlier favours the use of more automated systems whilst the requirement for resistance surveillance provides impetus for the use of systems that provide quantitative results and electronic data handling.

  16. Antifungal susceptibility testing.

    PubMed Central

    Rex, J H; Pfaller, M A; Rinaldi, M G; Polak, A; Galgiani, J N

    1993-01-01

    Unlike antibacterial susceptibility testing, reliable antifungal susceptibility testing is still largely in its infancy. Many methods have been described, but they produce widely discrepant results unless such factors as pH, inoculum size, medium formulation, incubation time, and incubation temperature are carefully controlled. Even when laboratories agree upon a common method, interlaboratory agreement may be poor. As a result of numerous collaborative projects carried out both independently and under the aegis of the Subcommittee on Antifungal Susceptibility Testing of the National Committee for Clinical Laboratory Standards, the effects of varying these factors have been extensively studied and a standard method which minimizes interlaboratory variability during the testing of Candida spp. and Cryptococcus neoformans has been proposed. This review summarizes this work, reviews the strengths and weaknesses of the proposed susceptibility testing standard, and identifies directions for future work. PMID:8269392

  17. Real-time video imaging as a new and rapid tool for antibiotic susceptibility testing by the disc diffusion method: a paradigm for evaluating resistance to imipenem and identifying extended-spectrum β-lactamases.

    PubMed

    Le Page, Stéphanie; Raoult, Didier; Rolain, Jean-Marc

    2015-01-01

    The disc diffusion method has long been considered the standard technique for antibiotic susceptibility testing (AST) in clinical microbiology laboratories because of its simplicity, reproducibility and low cost compared with commercial automated microdilution systems that are usually more rapid but less sensitive for detecting important mechanisms of resistance. Here we measured reading zone diameters around antibiotics in a series of 25 well-characterised Gram-negative bacteria by the disc diffusion technique in real-time using an Advencis Bio-System instrument consisting of a real-time high-resolution video imager in a dedicated incubator. The susceptibility of wild-type Gram-negative bacteria to imipenem, determined by reading the diameter of inhibition, was detectable as early as 3.5h (mean time 3.7 ± 0.45 h), whereas carbapenemase-producing Gram-negative bacteria could be correctly categorised as early as 3h (mean time 4.2 ± 0.8 h) of incubation. Similarly, the characteristic champagne cork aspect of extended-spectrum β-lactamase (ESBL) could be detected by the system as early as 3.5 h. Moreover, we present here for the first time video movies of the appearance of the diameter of inhibition by disc diffusion in real-time. This preliminary study using a new and innovative technology provides for a renewed interest for microbiologists who wish to continue to use the disc diffusion method as a reference method for AST. New video imaging technology presents a proof of concept that could improve the real-time management of patients with AST within a very rapid turnaround time and can provide a large financial saving for hospitals.

  18. Testing hydrodynamics schemes in galaxy disc simulations

    NASA Astrophysics Data System (ADS)

    Few, C. G.; Dobbs, C.; Pettitt, A.; Konstandin, L.

    2016-08-01

    We examine how three fundamentally different numerical hydrodynamics codes follow the evolution of an isothermal galactic disc with an external spiral potential. We compare an adaptive mesh refinement code (RAMSES), a smoothed particle hydrodynamics code (SPHNG), and a volume-discretized mesh-less code (GIZMO). Using standard refinement criteria, we find that RAMSES produces a disc that is less vertically concentrated and does not reach such high densities as the SPHNG or GIZMO runs. The gas surface density in the spiral arms increases at a lower rate for the RAMSES simulations compared to the other codes. There is also a greater degree of substructure in the SPHNG and GIZMO runs and secondary spiral arms are more pronounced. By resolving the Jeans length with a greater number of grid cells, we achieve more similar results to the Lagrangian codes used in this study. Other alterations to the refinement scheme (adding extra levels of refinement and refining based on local density gradients) are less successful in reducing the disparity between RAMSES and SPHNG/GIZMO. Although more similar, SPHNG displays different density distributions and vertical mass profiles to all modes of GIZMO (including the smoothed particle hydrodynamics version). This suggests differences also arise which are not intrinsic to the particular method but rather due to its implementation. The discrepancies between codes (in particular, the densities reached in the spiral arms) could potentially result in differences in the locations and time-scales for gravitational collapse, and therefore impact star formation activity in more complex galaxy disc simulations.

  19. Antifungal susceptibility testing of Malassezia yeast: comparison of two different methodologies.

    PubMed

    Rojas, Florencia D; Córdoba, Susana B; de Los Ángeles Sosa, María; Zalazar, Laura C; Fernández, Mariana S; Cattana, María E; Alegre, Liliana R; Carrillo-Muñoz, Alfonso J; Giusiano, Gustavo E

    2017-02-01

    All Malassezia species are lipophilic; thus, modifications are required in susceptibility testing methods to ensure their growth. Antifungal susceptibility of Malassezia species using agar and broth dilution methods has been studied. Currently, few tests using disc diffusion methods are being performed. The aim was to evaluate the in vitro susceptibility of Malassezia yeast against antifungal agents using broth microdilution and disc diffusion methods, then to compare both methodologies. Fifty Malassezia isolates were studied. Microdilution method was performed as described in reference document and agar diffusion test was performed using antifungal tablets and discs. To support growth, culture media were supplemented. To correlate methods, linear regression analysis and categorical agreement was determined. The strongest linear association was observed for fluconazole and miconazole. The highest agreement between both methods was observed for itraconazole and voriconazole and the lowest for amphotericin B and fluconazole. Although modifications made to disc diffusion method allowed to obtain susceptibility data for Malassezia yeast, variables cannot be associated through a linear correlation model, indicating that inhibition zone values cannot predict MIC value. According to the results, disc diffusion assay may not represent an alternative to determine antifungal susceptibility of Malassezia yeast.

  20. Diffusion Disk Susceptibility Testing with Cefaclor

    PubMed Central

    Shadomy, Smith; Carver, Melinda

    1978-01-01

    The reliability of the standardized 30-μg cephalothin disk and that of an experimental 30-μg cefaclor disk in predicting probable clinical susceptibility to cefaclor were compared. Quantitative determinations of cefaclor susceptibility were measured by the World Health Organization International Collaborative Study agar dilution procedure; diffusion disk tests were performed by the standardized U.S. Food and Drug Administration disk test. The cephalothin disk erred in predicting probable susceptibility in 52% of isolates of Enterococcus spp. resistant to 16 μg or less of cefaclor per ml; the cefaclor disk did not. The cephalothin disk erred in correctly predicting susceptibility in only 20% of cefaclor-susceptible isolates of Enterobacter spp.; the cefaclor disk correctly predicted susceptibility for 70%. These results indicate the need for further evaluation of a separate cefaclor disk for use in susceptibility testing with this new cephalosporin. PMID:646345

  1. Antimicrobial susceptibility and susceptibility testing of Mycoplasma hominis: a review.

    PubMed

    Bygdeman, S M; Mårdh, P A

    1983-01-01

    The determination of the minimal growth-inhibiting concentration (MIC), the minimal metabolism-inhibiting concentration (MMC), and the minimal mycoplasmacidal concentration (MCC) of various antimicrobial compounds for Mycoplasma hominis is influenced by the pH of the test media, the inoculum size, and the incubation time, although each of these factors generally do not affect the minimal concentration more than fourfold. M. hominis is resistant to beta-lactam antibiotics, vancomycin, sulfonamides, trimethoprim, and polymyxin B. There are great differences in the susceptibility of M. hominis to various macrolide antibiotics. Thus the organism is resistant to erythromycin and oleandomycin, moderately resistant to tylosin and spiramycin, susceptible to josamycin as well as to another macrolide drug, labelled M-4365G. M. hominis is also highly susceptible to the macrolide-like compound rosaramicin and to the tetracyclines (although resistant strains occur). It is susceptible to lincomycin and clindamycin, and moderately susceptible to chloramphenicol and rifampicin. The aminoglycosides have limited activity against M. hominis.

  2. Colistin susceptibility testing: evaluation of reliability for cystic fibrosis isolates of Pseudomonas aeruginosa and Stenotrophomonas maltophilia

    PubMed Central

    Moskowitz, Samuel M.; Garber, Elizabeth; Chen, Yunhua; Clock, Sarah A.; Tabibi, Setareh; Miller, Amanda K.; Doctor, Michael; Saiman, Lisa

    2010-01-01

    Objectives Antibiotic susceptibility methods that are commonly used to test bacterial isolates from patients with cystic fibrosis are of uncertain reliability for the polymyxins. To assess the reliability of four standard testing methods, this pilot study used a challenge set that included polymyxin-resistant isolates of Pseudomonas aeruginosa and Stenotrophomonas maltophilia. Methods Twenty-five P. aeruginosa and 12 S. maltophilia isolates were tested for susceptibility to colistin (polymyxin E). Repeatability (concordance of replicates performed concurrently), reproducibility (concordance of replicates performed over time) and comparability (concordance of different methods) of agar dilution, broth microdilution, Etest and disc diffusion were assessed through the use of descriptive statistics and scatterplot analyses. Results All four methods displayed excellent repeatability (overall concordance rate of 99%). However, analysis of reproducibility revealed substantially lower rates of concordance (74% for agar dilution, 84% for broth microdilution and Etest, and 91% for disc diffusion). In addition, comparability to agar dilution of the three other methods was generally poor, with overall rates of very major error ranging from 12% for broth microdilution to 18% for Etest and disc diffusion. Conclusions Compared with agar dilution, other susceptibility testing methods give high rates of apparent false polymyxin susceptibility for cystic fibrosis isolates of P. aeruginosa and S. maltophilia. Prospective study of the correlation between in vitro susceptibility and clinical response is needed to clarify whether these discrepancies reflect oversensitivity of the agar dilution method or insensitivity of the other methods. PMID:20430789

  3. Antianaerobic Antimicrobials: Spectrum and Susceptibility Testing

    PubMed Central

    Wexler, Hannah M.; Goldstein, Ellie J. C.

    2013-01-01

    SUMMARY Susceptibility testing of anaerobic bacteria recovered from selected cases can influence the choice of antimicrobial therapy. The Clinical and Laboratory Standards Institute (CLSI) has standardized many laboratory procedures, including anaerobic susceptibility testing (AST), and has published documents for AST. The standardization of testing methods by the CLSI allows comparisons of resistance trends among various laboratories. Susceptibility testing should be performed on organisms recovered from sterile body sites, those that are isolated in pure culture, or those that are clinically important and have variable or unique susceptibility patterns. Organisms that should be considered for individual isolate testing include highly virulent pathogens for which susceptibility cannot be predicted, such as Bacteroides, Prevotella, Fusobacterium, and Clostridium spp.; Bilophila wadsworthia; and Sutterella wadsworthensis. This review describes the current methods for AST in research and reference laboratories. These methods include the use of agar dilution, broth microdilution, Etest, and the spiral gradient endpoint system. The antimicrobials potentially effective against anaerobic bacteria include beta-lactams, combinations of beta-lactams and beta-lactamase inhibitors, metronidazole, chloramphenicol, clindamycin, macrolides, tetracyclines, and fluoroquinolones. The spectrum of efficacy, antimicrobial resistance mechanisms, and resistance patterns against these agents are described. PMID:23824372

  4. Antimicrobic susceptibility testing. A personal perspective.

    PubMed

    Sherris, J C

    1989-06-01

    The development of antimicrobic susceptibility testing is outlined with particular reference to standardization of procedures and organizational developments that have led to substantially improved performance. Special problems continue to be posed by increased proportions of opportunistic pathogens and newly recognized mechanisms of resistance, and these require updating. The role of automated procedures and technical problems in MBC and serum bactericidal testing are considered.

  5. Susceptibility testing of Entamoeba histolytica

    SciTech Connect

    Cedeno, J.R.; Krogstad, D.J.

    1983-12-01

    The growth of Entamoeba histolytica in microtiter plates in vitro in a variety of environments with reduced oxygen tensions is reported. With 3% O/sub 2/, 3% CO/sub 2/, and 94% N/sub 2/, the parasite growth in microtiter plates was identical to that in screw-capped culture tubes, as measured by (/sup 3/H)thymidine incorporation and by quantitative parasite counts. There were no significant differences between the drug concentrations necessary to inhibit parasite growth by 50% based on (/sup 3/H)thymidine incorporation vs those defined by quantitative parasite counts for the 15 antimicrobial agents tested (including seven drugs used for the treatment of amebiasis). This technique provides a reproducible method to quantitate the activity of potential antiamebic agents in vitro. The isotopic method should be of particular value in defining the metabolism of the parasite and effects of antimicrobial agents on it, whereas the morphologic method may be more valuable for workers with limited resources available to them.

  6. [Rapid antibiotic susceptibility test in Clinical Microbiology].

    PubMed

    March Rosselló, Gabriel Alberto; Bratos Pérez, Miguel Ángel

    2016-01-01

    The most widely used antibiotic susceptibility testing methods in Clinical Microbiology are based on the phenotypic detection of antibiotic resistance by measuring bacterial growth in the presence of the antibiotic being tested. These conventional methods take typically 24hours to obtain results. A review is presented here of recently developed techniques for the rapid determination of antibiotic susceptibility. Data obtained with different methods such as molecular techniques, flow cytometry, chemiluminescence, mass spectrometry, commercial methods used in routine work, colorimetric methods, nephelometry, microarrays, microfluids, and methods based on cell disruption and sequencing, are analyzed and discussed in detail.

  7. [Methods for in vitro antifungal susceptibility testing].

    PubMed

    Dannaoui, Eric

    2006-01-01

    During the last years, a large amount of work has been completed to improve the methods used for in vitro antifungal susceptibility testing. Reference techniques are currently available both for yeasts and filamentous fungi, but in some instances, technical improvement are needed. Etest is another well standardized method that can be used as an alternative on a routine basis in the clinical microbiology laboratory. Studies of in vitro-in vivo correlations have led to the definition of susceptibility breakpoints for yeasts for fluconazole, itraconazole, and flucytosine.

  8. [Antimicrobial susceptibility testing of anaerobic bacteria].

    PubMed

    García-Sánchez, José E; García-Sánchez, Enrique; García-García, María Inmaculada

    2014-02-01

    The anaerobic bacteria resistance to antibiotics is increasing, and even has appeared against the most active of those, like metronidazol and carbapenems. This fact forces to make and periodical sensibility tests -at least in the most aggressive and virulent species, in cases that they are isolated from life locations and in the absence of therapeutic response- to check the local sensibility and to establish suitable empiric therapies, all based on multicentric studies carried out in order to this or well to check the activity of new antibiotics. For the laboratory routine, the easiest sensibility method is the E-test/MIC evaluator. Another alternative is microdilution, that's only normalized for Bacteroides. There are preliminary facts that allow the use of disc diffusion method in some species of Bacteroides and Clostridium. For the temporal and multicentric studies, the procedure is dilution in agar plate, the reference method.

  9. Hydrogen gas embrittlement and the disc pressure test

    NASA Technical Reports Server (NTRS)

    Bachelet, E. J.; Troiano, A. R.

    1973-01-01

    A disc pressure test has been used to study the influenced of a hydrogen gas environment on the mechanical properties of three high strength superalloys, Inconel 718, L-605 and A-286, in static and dynamic conditions. The influence of the hydrogen pressure, loading rate, temperature, mechanical and thermal fatigue has investigated. The permeation characteristics of Inconel 718 have been determined in collaboration with the French AEC. The results complemented by a fractographic study are consistent either with a stress-sorption or with an internal embrittlement type of mechanism.

  10. Utility of direct susceptibility testing on blood cultures: is it still worthwhile?

    PubMed

    Menon, Vidthiya; Lahanas, Sophie; Janto, Catherine; Lee, Andie

    2016-06-01

    Earlier targeted therapy for bacteraemia optimizes patient outcomes and reduces broad spectrum antibiotic use. Standardized susceptibility testing results are available at 36-48 h. Direct disc susceptibility testing from blood culture broth reduces time to results but the inoculum is not standardized. No studies have looked at the clinical utility of direct susceptibility results. This retrospective cohort study aimed to assess the correlation between direct and formal testing methods as well as the clinical utility of direct susceptibility results. 160 episodes of bacteraemia with paired direct and formal susceptibility testing were studied. Direct disc testing was performed on blood culture broth. Formal testing was performed on isolates, using automated broth microdilution or Etests. The rate of error was 9.0 % (95 % CI 7.0-11.6 %). In 10 cases (6.3 %, 95 % CI 3.0-11.2 %), inappropriate antibiotics were used due to direct susceptibility results, including two cases with ineffective (as opposed to too broad) antibiotics being used. Antibiotics were changed in 28.1 % of cases once direct susceptibility data was available. There was a decreased time to effective antibiotics in 9.3 % (95 % CI 5.3-15.0 %), and a decreased time to a targeted antibiotics in 14.3 % (95 % CI 9.3-20.8 %) of cases. Despite the error rate, the advantages of earlier times to effective and targeted antibiotics justifies continuing direct testing in bacteraemia episodes with Gram-negative rods. In the Gram-positive group, given the contamination rate, the availability of adjunctive PCR, and the fact that early identification of the isolate could equally influence antibiotic choices, direct susceptibility testing may no longer be warranted.

  11. Vitamin D Receptor Gene, Matrix Metalloproteinase 3 Polymorphisms and the Risk of Intervertebral Disc Degeneration Susceptibility: Meta-Analysis

    PubMed Central

    Huang, Yongjing; Zhao, Shujie; Xu, Nanwei

    2016-01-01

    Several studies have evaluated the association between vitamin D receptor, matrix metalloproteinase 3 (MMP-3) polymorphisms and the risk of intervertebral disc degeneration susceptibility. The findings were inconsistent. This meta-analysis aimed to systematically assess the association between vitamin D receptor, MMP-3 polymorphisms and the risk of intervertebral disc degeneration susceptibility. A search of various databases was done covering all papers published until December 31th, 2014. Eight, 4, 3 studies were finally included that addressed the risk of intervertebral disc degeneration susceptibility and vitamin D receptor FokI (rs2228570), ApaI (rs7975232), and MMP-3 (rs731236) polymorphisms, respectively. FokI (f vs. F: summary odds ratio [OR], 1.13; 95% confidence interval [CI], 0.76–1.69; ff vs. FF: OR, 1.02; 95% CI, 0.59–1.77; ff vs. Ff/FF: OR, 1.05; 95% CI, 0.70–1.58), ApaI (a vs. A: OR, 0.73; 95% CI, 0.45–1.19; aa vs. AA: OR, 0.53; 95% CI, 0.22–1.25 p=0.14; aa vs. AA/Aa: OR, 0.69; 95% CI, 0.53–0.89) in the vitamin D receptor gene and MMP3 polymorphisms (5A vs. 6A: OR, 1.92; 95% CI, 0.77–4.80; 5A5A vs. 6A6A: OR, 2.17; 95% CI, 0.75–6.24; 5A5A vs. 5A6A/6A6A: OR, 1.58; 95% CI, 0.72–3.44) were not obviously associated with risk of intervertebral disc degeneration susceptibility. FokI, ApaI polymorphisms in the vitamin D receptor gene and MMP-3 polymorphism are not obvious risk factors for intervertebral disc degeneration susceptibility. PMID:27790329

  12. Tests and developments of the PANDA Endcap Disc DIRC

    NASA Astrophysics Data System (ADS)

    Etzelmüller, E.; Belias, A.; Dzhygadlo, R.; Gerhardt, A.; Götzen, K.; Kalicy, G.; Krebs, M.; Lehmann, D.; Nerling, F.; Patsyuk, M.; Peters, K.; Schepers, G.; Schmitt, L.; Schwarz, C.; Schwiening, J.; Traxler, M.; Zühlsdorf, M.; Britting, A.; Eyrich, W.; Lehmann, A.; Pfaffinger, M.; Uhlig, F.; Düren, M.; Föhl, K.; Hayrapetyan, A.; Kröck, B.; Merle, O.; Rieke, J.; Schmidt, M.; Cowie, E.; Keri, T.; Achenbach, P.; Cardinali, M.; Hoek, M.; Lauth, W.; Schlimme, S.; Sfienti, C.; Thiel, M.

    2016-04-01

    The PANDA experiment at the future Facility for Antiproton and Ion Research (FAIR) requires excellent particle identification. Two different DIRC detectors will utilize internally reflected Cherenkov light of charged particles to enable the separation of pions and kaons up to momenta of 4 GeV/c. The Endcap Disc DIRC will be placed in the forward endcap of PANDA's central spectrometer covering polar angles between 5° and 22°. Its final design is based on MCP-PMTs for the photon detection and an optical system made of fused silica. A new prototype has been investigated during a test beam at CERN in May 2015 and first results will be presented. In addition a new synthetic fused silica material by Nikon has been tested and was found to be radiation hard.

  13. [A new rapid antibiotic susceptibility test for enteric bacteria using a color change method].

    PubMed

    Kocagöz, T; Hayran, M; Kocagöz, S

    1988-01-01

    The rapid antibiotic susceptibility tests that have been developed so far cannot be used in daily work, because of their many difficulties and disadvantages. We have developed a new antibiotic susceptibility test for enteric bacteria which gives the result in 4 hours, easy to perform and inexpensive. This method depends upon the mechanism which detects the acid formed by the bacteria, by the change of the color of the pH indicator in the medium. The susceptibility of 110 different isolates of enteric bacteria (E. coli, Klebsiella, Salmonella, Shigella, Proteus, Enterobacter) to ampicillin, amikacin, trimethoprim-sulfamethoxazole, cephradine, cefazolin, erythromycin, gentamicin, and ofloxacin is examined by this new "Rapid Color Change Test" and disc diffusion method. For most organisms tested, there was a good correlation between the results of the two methods. The overall agreement is found to be 91.43%.

  14. Electromagnetic Radiation System (EMRS) for Susceptibility Testing.

    DTIC Science & Technology

    ELECTROMAGNETIC COMPATIBILITY, *ELECTROMAGNETIC SUSCEPTIBILITY, COMMUNICATION EQUIPMENT, ELECTRONIC EQUIPMENT, ELECTROMAGNETIC RADIATION , ANTENNAS, ELECTROMAGNETIC INTERFERENCE, RADAR SIGNALS, RADIO SIGNALS, FIELD INTENSITY.

  15. Neuropsychological Test Performance and Hypnotic Susceptibility.

    ERIC Educational Resources Information Center

    Query, William T.; And Others

    1983-01-01

    Examined the relationship between brain-behavior and hypnotic susceptibility in 70 alcoholic patients, using the Stanford Hypnotic Susceptibility Scale and its Fromm-Weingarten modification. Results showed the two scales were interchangeable insofar as they measured the same ability, and indicated that hypnotic susceptibility is related to…

  16. 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.

  17. Awareness of Cancer Susceptibility Genetic Testing

    PubMed Central

    Mai, Phuong L.; Vadaparampil, Susan Thomas; Breen, Nancy; McNeel, Timothy S.; Wideroff, Louise; Graubard, Barry I.

    2014-01-01

    Background Genetic testing for several cancer susceptibility syndromes is clinically available; however, existing data suggest limited population awareness of such tests. Purpose To examine awareness regarding cancer genetic testing in the U.S. population aged ≥25 years in the 2000, 2005, and 2010 National Health Interview Surveys. Methods The weighted percentages of respondents aware of cancer genetic tests, and percent changes from 2000–2005 and 2005–2010, overall and by demographic, family history, and healthcare factors were calculated. Interactions were used to evaluate the patterns of change in awareness between 2005 and 2010 among subgroups within each factor. To evaluate associations with awareness in 2005 and 2010, percentages were adjusted for covariates using multiple logistic regression. The analysis was performed in 2012. Results Awareness decreased from 44.4% to 41.5% (p<0.001) between 2000 and 2005, and increased to 47.0% (p<0.001) in 2010. Awareness increased between 2005 and 2010 in most subgroups, particularly among individuals in the South (p-interaction=0.03) or with a usual place of care (p-interaction=0.01). In 2005 and 2010, awareness was positively associated with personal or family cancer history and high perceived cancer risk, and inversely associated with racial/ethnic minorities, age 25–39 or ≥60 years, male gender, lower education and income levels, public or no health insurance, and no provider contact in 12 months. Conclusions Despite improvement from 2005 to 2010, ≤50% of the U.S. adult population was aware of cancer genetic testing in 2010. Notably, disparities persist for racial/ethnic minorities and individuals with limited health care access or income. PMID:24745633

  18. Development of EUCAST disk diffusion method for susceptibility testing of the Bacteroides fragilis group isolates.

    PubMed

    Nagy, Elisabeth; Justesen, Ulrik Stenz; Eitel, Zsuzsa; Urbán, Edit

    2015-02-01

    With the emergence of antibiotic resistance among Bacteroides fragilis group isolates the need of susceptibility testing in routine laboratories is increasing. The aims of the present study were to evaluate the disk diffusion method for susceptibility testing in case of different clinical isolates of Bacteroides spp by comparing zone diameter results with MICs obtained earlier during an Europe-wide antibiotic susceptibility surveillance, and to propose zone diameter breakpoints, which correlate for the EUCAST MIC breakpoints. We tested 381 clinical isolates of the B. fragilis group to amoxicillin/clavulanic acid, cefoxitin, clindamycin, imipenem, metronidazole, moxifloxacin, piperacillin/tazobactam, tigecycline by agar dilution method previously. The inhibition zones of the same antibiotics including meropenem disc were determined by the disc diffusion on Brucella blood agar supplemented with haemin and vitamin K1. Plates were incubated at 37 °C in an anaerobic atmosphere for 24 h. The zone diameters were read at 100% inhibition. In case of discrepant results MICs were determined by gradient test and compared with the inhibition zones on the same plate. We found a good agreement between the inhibition zone diameters and the MICs for imipenem, metronidazole, moxifloxacin and tigecyclin. The inhibition zone diameters of meropenem also separated clearly the isolates, which can be considered wild-type isolates. In case of amoxicillin/clavulanic acid and piperacillin/tazobactam intermediate and susceptible isolates according to the MIC determination, overlap during the zone diameter determination. Isolates with an inhibition zone <23 mm for amoxicillin/clavulanic acid and <25 mm for piperacillin/tazobactam should be retested by a MIC determination method. The 10 μg clindamycin disc clearly separated the resistant and the susceptible population of B. fragilis group strains. In the case of cefoxitin only resistant population could be separated with an inhibition

  19. Reliability of provocative tests of motion sickness susceptibility

    NASA Technical Reports Server (NTRS)

    Calkins, D. S.; Reschke, M. F.; Kennedy, R. S.; Dunlop, W. P.

    1987-01-01

    Test-retest reliability values were derived from motion sickness susceptibility scores obtained from two successive exposures to each of three tests: (1) Coriolis sickness sensitivity test; (2) staircase velocity movement test; and (3) parabolic flight static chair test. The reliability of the three tests ranged from 0.70 to 0.88. Normalizing values from predictors with skewed distributions improved the reliability.

  20. [Should metal alloy discs be used for patch testing in suspected metal implant intolerance reaction?].

    PubMed

    Thomas, P; Geier, J; Dickel, H; Diepgen, T; Hillen, U; Kreft, B; Schnuch, A; Szliska, C; Mahler, V

    2015-11-01

    Intolerance reactions to metal implants may be caused by metal allergy. However, prior to implantation, patch testing should not be done in a prophylactic-prophetic approach. Pre-implant patch testing should only be performed to verify or exclude metal allergy in patients with a reported respective history. In the case of implant-in particular arthroplasty-related complications like, for example, pain, effusion, skin changes, reduced range of motion, or loosening, orthopedic-surgical differential diagnostics should be performed first. Allergological workup of suspected metal implant allergy should be done with the DKG baseline series which contains nickel-, cobalt- and chromium-preparations. Various studies assessing the usefulness of metal alloy discs for patch testing proved that this approach does not give reliable information about metal allergy. Positive patch test reactions to the discs cannot be assigned to a specific metal within the disc alloy components. Furthermore, availability of such metal discs might be an invitation to uncritical testing. Accordingly, due to lack of benefit in comparison to patch testing with standardized metal salt preparations, we do not recommend patch testing with metal alloy discs.

  1. Automatic Radiated Susceptibility Test System for Payload Equipment

    NASA Technical Reports Server (NTRS)

    Ngo, Hoai T.; Sturman, John C.; Sargent, Noel B.

    1995-01-01

    An automatic radiated susceptibility test system (ARSTS) was developed for NASA Lewis Research Center's Electro-magnetic Interference laboratory. According to MSFC-SPEC 521B, any electrical or electronic equipment that will be transported by the spacelab and space shuttle must be tested for susceptibility to electromagnetic interference. This state-of-the-art automatic test system performs necessary calculations; analyzes, processes, and records a great quantity of measured data; and monitors the equipment being tested in real-time and with minimal user intervention. ARSTS reduces costly test time, increases test accuracy, and provides reliable test results.

  2. Use of a proposed antimicrobial susceptibility testing method for Haemophilus parasuis.

    PubMed

    Dayao, Denise Ann E; Kienzle, Marco; Gibson, Justine S; Blackall, Patrick J; Turni, Conny

    2014-08-27

    The aim of this study was to examine the antimicrobial susceptibility of 97 Haemophilus parasuis cultured from Australian pigs. As there is no existing standard antimicrobial susceptibility technique available for H. parasuis, methods utilising the supplemented media, BA/SN for disc diffusion and test medium broth (TMB) for a microdilution technique, were initially evaluated with the reference strains recommended by the Clinical and Laboratory Standards Institute. The results of the media evaluation suggested that BA/SN and TMB can be used as suitable media for susceptibility testing of H. parasuis. The proposed microdilution technique was then used with 97 H. parasuis isolates and nine antimicrobial agents. The study found that Australian isolates showed elevated minimum inhibitory concentrations (MICs) for ampicillin (1%), penicillin (2%), erythromycin (7%), tulathromycin (9%), tilmicosin (22%), tetracycline (31%) and trimethoprim-sulfamethoxazole (40%). This study has described potential antimicrobial susceptibility methods for H. parasuis and has detected a low percentage of Australian H. parasuis isolates with elevated antimicrobial MICs.

  3. Are Creativity Tests Susceptible to Coaching?

    ERIC Educational Resources Information Center

    Fairweather, Elizabeth C.; Cramond, Bonnie; Landis, Rebecca Nordin

    2015-01-01

    Critics of creativity tests, some of which are used widely in determining student eligibility for special educational opportunities such as gifted programs, claim that scores on these tests can be improved with specific training on the scoring components of the tests. However, we could find no empirical evidence supporting this claim. So, we…

  4. Posterior pelvic pain provocation test is negative in patients with lumbar herniated discs.

    PubMed

    Gutke, Annelie; Hansson, Eva Roos; Zetherström, Gunilla; Ostgaard, Hans Christian

    2009-07-01

    The classification of pelvic girdle pain can only be reached after lumbar causes have been excluded by a clinical examination. During clinical examination, the posterior pelvic pain provocation test is a well-established method for verifying pelvic girdle pain. However, a criticism of pelvic pain provocation tests is that they may have an effect on lumbar structures, thus yielding false-positive results. The posterior pelvic pain provocation test was performed with four groups of patients: patients with computed tomography-verified disc herniations (1) on the waiting list for surgery (14 women; 9 men); (2) 6 weeks after disc surgery (18 women, 12 men); (3) pregnant women seeking care for pelvic girdle pain (n = 25); and (4) women with persistent pelvic girdle pain after delivery (n = 32). The sensitivity of the posterior pelvic pain provocation test was 0.88 and the specificity was 0.89. The positive predictive value was 0.89 and the negative predictive value was 0.87. Analysis of only women showed similar results. In our study, the posterior pelvic pain provocation test was negative in patients with a well-defined lumbar diagnosis of lumbar disc herniation, both before and after disc surgery. Our results are an important step toward the more accurate classification of lumbopelvic pain.

  5. Comparison of susceptibility patterns using commercially available susceptibility testing methods performed on prevalent Candida spp.

    PubMed

    Cretella, David; Barber, Katie E; King, S Travis; Stover, Kayla R

    2016-12-01

    The rising rates of invasive fungal infections caused by non-albicans Candida and the increasing emergence of antifungal resistance complicate the management of invasive candidiasis. Accurate and timely antifungal susceptibility testing is critical to targeting antifungal therapy. The purpose of this study was to compare commercially available susceptibility testing methods using prospectively collected Candida isolates. Susceptibility testing was performed on 74 Candida isolates collected from July 2014 to March 2015 using broth microdilution according to the Clinical and Laboratory Standards Institute method, Etest, Vitek 2 (YS-05) and Sensititre. Essential agreement and categorical agreement (CA) were assessed using the reference method. Of the 34 total blood isolates collected, Candida albicans comprised only 38 % (13) of the Candida spp. with Candidaglabrata being nearly as prevalent (29 %, 10). CA using Etest was 86 % for fluconazole, 72 % for caspofungin, 98 % for micafungin and 97 % for anidulafungin. Vitek 2 CA was 90 % for fluconazole and 98 % for caspofungin. Sensititre CA was 93 % for fluconazole, 98 % for caspofungin, 98 % for micafungin and 100 % for anidulafungin. Although our study tested a small population of Candida isolates, our results were variable by method. When implementing antifungal susceptibility testing, clinicians should be aware of the strengths and limitations of each testing method.

  6. Susceptibility testing of anaerobic bacteria: myth, magic, or method?

    PubMed Central

    Wexler, H M

    1991-01-01

    The demand for susceptibility testing of anaerobes has increased, yet consensus as to procedure and interpretation in this area has not been achieved. While routine testing of anaerobic isolates is not needed, certain isolates in specific clinical settings should be tested. Also, laboratories may monitor their local antibiograms by doing periodic surveillance batch testing. The National Committee for Clinical Laboratory Standards has published a protocol of methods approved for susceptibility testing of anaerobic bacteria. Both agar and broth microdilution are included; however, the broth disk elution method is no longer approved by the National Committee for Clinical Laboratory Standards because of method-related interpretive errors. A number of newer methods are undergoing evaluation and seem promising. Clinicians and microbiologists reviewing susceptibility reports should be aware of sources of variability in the test results. Variables in susceptibility testing of anaerobes include the media and methods used, organisms chosen for testing, breakpoints chosen for interpretation, antibiotic, and determination of endpoint. Clustering of MICs around the breakpoint may lead to significant variability in test results. Adherence of testing laboratories to approved methods and careful descriptions of the method and the breakpoints used for interpretation would facilitate interlaboratory comparisons and allow problems of emerging resistance to be noted. A variety of resistance mechanisms occurs in anaerobic bacteria, including the production of beta-lactamase and other drug-inactivating enzymes, alteration of target proteins, and inability of the drug to penetrate the bacterial wall. Antimicrobial resistance patterns in the United States and abroad are described. PMID:1747863

  7. Antifungal Susceptibility Testing of Ascomycetous Yeasts Isolated from Animals

    PubMed Central

    Álvarez-Pérez, Sergio; García, Marta E.; Peláez, Teresa; Martínez-Nevado, Eva

    2016-01-01

    Recent studies suggest that antifungal resistance in yeast isolates of veterinary origin may be an underdiagnosed threat. We tested a collection of 92 ascomycetous yeast isolates that were obtained in Spain from birds, mammals and insects for antifungal susceptibility. MICs to amphotericin B and azoles were low, and no resistant isolates were detected. Despite these results, and given the potential role of animals as reservoirs of resistant strains, continuous monitoring of antifungal susceptibility in the veterinary setting is recommended. PMID:27216048

  8. Improved method for azole antifungal susceptibility testing.

    PubMed Central

    Gordon, M A; Lapa, E W; Passero, P G

    1988-01-01

    A reproducible method is described for the determination of the MICs of ketoconazole, miconazole, fluconazole, and itraconazole with sharp endpoints when employed with either yeasts or molds. A semisolid medium is used with controlled pH and standardized inoculum. The time of reading results is a critical factor in the conduct of this test. The medium is simple to prepare and has a relatively long refrigerator shelf life in a user-ready state, requiring only the addition of a freshly prepared inoculum after restoration to room temperature. Images PMID:2846651

  9. 21 CFR 866.1640 - Antimicrobial susceptibility test powder.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Antimicrobial susceptibility test powder. 866.1640 Section 866.1640 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... agents. Test results are used to determine the antimicrobial agent of choice in the treatment...

  10. Antimicrobial resistance in campylobacter: susceptibility testing methods and resistance trends.

    PubMed

    Ge, Beilei; Wang, Fei; Sjölund-Karlsson, Maria; McDermott, Patrick F

    2013-10-01

    Most Campylobacter infections are self-limiting but antimicrobial treatment (e.g., macrolides, fluoroquinolones) is necessary in severe or prolonged cases. Susceptibility testing continues to play a critical role in guiding therapy and epidemiological monitoring of resistance. The methods of choice for Campylobacter recommended by the Clinical and Laboratory Standards Institute (CLSI) are agar dilution and broth microdilution, while a disk diffusion method was recently standardized by the European Committee on Antimicrobial Susceptibility Testing (EUCAST). Macrolides, quinolones, and tetracyclines are among the common antimicrobials recommended for testing. Molecular determination of Campylobacter resistance via DNA sequencing or PCR-based methods has been performed. High levels of resistance to tetracycline and ciprofloxacin are frequently reported by many national surveillance programs, but resistance to erythromycin and gentamicin in Campylobacter jejuni remains low. Nonetheless, variations in susceptibility observed over time underscore the need for continued public health monitoring of Campylobacter resistance from humans, animals, and food.

  11. US physicians' attitudes toward genetic testing for cancer susceptibility.

    PubMed

    Freedman, A N; Wideroff, L; Olson, L; Davis, W; Klabunde, C; Srinath, K P; Reeve, B B; Croyle, R T; Ballard-Barbash, R

    2003-07-01

    Genetic testing for an inherited susceptibility to cancer is an emerging technology in medical practice. Little information is currently available about physicians' attitudes toward these tests. To assess US physicians' opinions on unresolved issues surrounding genetic testing, a 15-min survey was administered to a stratified random sample of 1,251 physicians from 8 specialties, selected from a file of all licensed physicians in the US (response rate = 71.0%). Dependent measures included physicians' attitudes toward genetic counseling and testing qualifications, availability of guidelines, patient confidentiality and insurance discrimination issues, and clinical utility of genetic tests. More than 89% of physicians reported a need for physician guidelines, 81% thought that patients with positive genetic test results are at risk for insurance discrimination, and more than 53% thought that it was difficult to ensure the confidentiality of test results. Almost 25% indicated that genetic tests for cancer susceptibility have too many inaccurate or ambiguous results; nearly 75% thought that clear guidelines are not available for managing patients with positive test results. Only 29% of physicians reported feeling qualified to provide genetic counseling to their patients. More than 84% of oncologists considered themselves qualified to recommend genetic testing to their patients compared with 40% of primary care physicians (PCPs), and 57% of tertiary care physicians (TCPs). US physicians expressed great uncertainty about issues surrounding genetic testing for cancer susceptibility. Results of this national survey underscore the need to provide physicians with clear guidelines on the use of genetic cancer susceptibility tests and effective medical training on their appropriate implementation.

  12. Antimycobacterial susceptibility testing methods for natural products research

    PubMed Central

    Sánchez, Juan Gabriel Bueno; Kouznetsov, Vladimir V.

    2010-01-01

    The emergence of multidrug-resistant strains of Mycobacterium tuberculosis underscores the need of continuous developments on new and efficient methods to determine the susceptibility of isolates of M. tuberculosis in the search for novel antimicrobial agents. Natural products constitute an important source of new drugs, but design and implementation of antimycobacterial susceptibility testing methods are necessary for evaluate the different extracts and compounds. A number of biological assay methodologies are in current use, ranging from the classical disk diffusion and broth dilution assay format, to radiorespirometric (BACTEC), dye-based, and fluorescent/luminescence reporter assays. This review presents an analysis on the in vitro susceptibility testing methods developed for determinate antitubercular activity in natural products and related compounds (semi-synthetic natural products and natural products-derived compounds) and the criteria to select the adequate method for determination of biological activity of new natural products. PMID:24031490

  13. Mechanical testing and modelling of carbon-carbon composites for aircraft disc brakes

    NASA Astrophysics Data System (ADS)

    Bradley, Luke R.

    The objective of this study is to improve the understanding of the stress distributions and failure mechanisms experienced by carbon-carbon composite aircraft brake discs using finite element (FE) analyses. The project has been carried out in association with Dunlop Aerospace as an EPSRC CASE studentship. It therefore focuses on the carbon-carbon composite brake disc material produced by Dunlop Aerospace, although it is envisaged that the approach will have broader applications for modelling and mechanical testing of carbon-carbon composites in general. The disc brake material is a laminated carbon-carbon composite comprised of poly(acrylonitrile) (PAN) derived carbon fibres in a chemical vapour infiltration (CVI) deposited matrix, in which the reinforcement is present in both continuous fibre and chopped fibre forms. To pave the way for the finite element analysis, a comprehensive study of the mechanical properties of the carbon-carbon composite material was carried out. This focused largely, but not entirely, on model composite materials formulated using structural elements of the disc brake material. The strengths and moduli of these materials were measured in tension, compression and shear in several orientations. It was found that the stress-strain behaviour of the materials were linear in directions where there was some continuous fibre reinforcement, but non-linear when this was not the case. In all orientations, some degree of non-linearity was observed in the shear stress-strain response of the materials. However, this non-linearity was generally not large enough to pose a problem for the estimation of elastic moduli. Evidence was found for negative Poisson's ratio behaviour in some orientations of the material in tension. Additionally, the through-thickness properties of the composite, including interlaminar shear strength, were shown to be positively related to bulk density. The in-plane properties were mostly unrelated to bulk density over the range of

  14. A test of truncation in the accretion discs of X-ray Binaries.

    NASA Astrophysics Data System (ADS)

    Eckersall, A.

    2016-06-01

    The truncated-disc model is generally used to help explain the change between the soft and hard states in X-ray Binaries, where the standard accretion disc is truncated in the inner regions and replaced by a radiatively inefficient accretion flow. There is still disagreement though in the extent of this truncation, particularly in at what point truncation begins. Here we analyze XMM EPIC-pn spectra in both the soft and hard states for a number of galactic XRBs, along with RGS data and the latest absorption and emission models to get an independent fit for the ISM column densities for each source. Specifically, we assume the 'canonical' model where the luminous accretion disc extends down to the innermost stable orbit at 6r_g, and construct a spectral model accounting for thermal, reflection and Compton processes ensuring consistent geometrical properties of the models. Rather than attempting to infer the inner disc location from spectral fitting and/or reflection models, we instead attempt a direct test of whether a consistent model will fit assuming no truncation. We discuss the implications for emission models of XRBs.

  15. Effect of lubricants on friction in laboratory tests of a total disc replacement device.

    PubMed

    Moghadas, Parshia; Mahomed, Aziza; Hukins, David W L; Shepherd, Duncan E T

    2013-09-01

    Some designs of total disc replacement devices have articulating bearing surfaces, and these devices are tested in vitro with a lubricant of diluted calf serum. It is believed that the lubricant found in total disc replacement devices in vivo is interstitial fluid that may have properties between that in Ringer's solution and diluted calf serum. To investigate the effect of lubricants, a set of friction tests were performed on a generic model of a metal against metal ball-and-socket total disc replacement device. Two devices were tested: one with a ball radius of 10 mm and other with a ball radius of 16 mm; each device had a radial clearance of 0.015 mm. A spine simulator was used to measure frictional torque for each device in axial rotation, flexion-extension and lateral bending at frequencies of 0.25-2 Hz, under 1200 N axial load. Each device was tested with two different lubricants: a solution of new born calf serum diluted with deionised water and Ringer's solution. The results showed that the frictional torque generated between the bearing surfaces was significantly higher in Ringer's solution than in diluted calf serum. The use of Ringer's solution as a lubricant provides a stringent test condition to detect possible problems. Diluted calf serum is more likely to provide an environment closer to that in vivo. However, the precise properties of the fluid lubricating a total disc replacement device are not known; hence, tests using diluted calf serum may not necessarily give the same results as those obtained in vivo.

  16. 21 CFR 866.1640 - Antimicrobial susceptibility test powder.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Antimicrobial susceptibility test powder. 866.1640 Section 866.1640 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Diagnostic Devices § 866.1640...

  17. 21 CFR 866.1640 - Antimicrobial susceptibility test powder.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Antimicrobial susceptibility test powder. 866.1640 Section 866.1640 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Diagnostic Devices § 866.1640...

  18. 21 CFR 866.1640 - Antimicrobial susceptibility test powder.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Antimicrobial susceptibility test powder. 866.1640 Section 866.1640 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Diagnostic Devices § 866.1640...

  19. 21 CFR 866.1640 - Antimicrobial susceptibility test powder.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Antimicrobial susceptibility test powder. 866.1640 Section 866.1640 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Diagnostic Devices § 866.1640...

  20. Rapid flow cytometric susceptibility testing of Candida albicans.

    PubMed Central

    Ramani, R; Ramani, A; Wong, S J

    1997-01-01

    A rapid flow cytometric assay for in vitro antifungal drug susceptibility testing was developed by adapting the proposed reference method for broth macrodilution testing of yeasts. Membrane permeability changes caused by the antifungal agent were measured by flow cytometry using propidium iodide, a nucleic acid-binding fluorochrome largely excluded by the intact cell membrane. We determined the in vitro susceptibility of 31 Candida albicans isolates and two quality control strains (Candida parapsilosis ATCC 22019 and Candida krusei ATCC 6258) to amphotericin B and fluconazole. Amphotericin B MICs ranged from 0.03 to 2.0 microg/ml, while fluconazole MICs ranged from 0.125 to 128 microg/ml. This method results in clear-cut endpoints that were reproducible. Four-hour incubation was required for fluconazole, whereas a 2-h incubation was sufficient for amphotericin B to provide MICs comparable to the reference macrodilution method developed by the National Committee for Clinical Laboratory Standards Subcommittee on Antifungal Susceptibility Tests. Results of these studies show that flow cytometry provides a rapid and sensitive in vitro method for antifungal susceptibility testing of C. albicans. PMID:9276410

  1. 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

  2. Paper based point-of-care testing disc for multiplex whole cell bacteria analysis.

    PubMed

    Li, Chen-zhong; Vandenberg, Katherine; Prabhulkar, Shradha; Zhu, Xuena; Schneper, Lisa; Methee, Kalai; Rosser, Charles J; Almeide, Eugenio

    2011-07-15

    Point-of-care testing (POCT) of infectious bacterial agents offers substantial benefits for disease diagnosis, mainly by shortening the time required to obtain results and by making the test available bedside or at remote care centers. Immunochromatographic lateral flow biosensors offer a low cost, highly sensitive platform for POCT. In this article, we describe the fabrication and testing of a multiplex immuno-disc sensor for the specific detection of Pseudomonas aeruginosa and Staphylococcus aureus. Antibody conjugated gold nanoparticles were used as the signaling agents. The detection range of the bacteria lies within 500-5000 CFU/ml. The advantage of the immuno-disc sensor is that it does not require any preprocessing of biological sample and is capable of whole cell bacterial detection. We also describe the design and fabrication of a compact portable device which converts the color intensity of the gold nanoparticles that accumulate at the test region into a quantitative voltage reading proportional to the bacterial concentration in the sample. The combination of the immuno-disc and the portable color reader provides a rapid, sensitive, low cost, and quantitative tool for the detection of a panel of infectious agents present in the patient sample.

  3. AGARD (Advisory Group for Aerospace Research & Development) Engine Disc Cooperative Test Programme,

    DTIC Science & Technology

    1988-08-01

    4薗ii 759 so A AOR!nRU spa A44 IFOR I L J32 I 2 11I1L2 1. 1111. BBIC fiLL W;UV AGARM36R-766 AGARD REPORT No.766 AGARD Engine Disc Cooperative Test...J \\ND MlR I ItON \\I (MROi\\NIS.\\I ION 1)t I RiNI Ir iIM I 1~ .\\%NII I NORIp A(6ARI) Report No.700 AGARD ENGINE DISC (’O )PERAI IVE TEST PROG;RAMME h...cim p, met for manyv years. In I 9X2 a Suh-comrnittee on ’-Damage Tolerance Concepts for Critical Engine Comiponents’ "as formed ito studs the

  4. Innovative antimicrobial susceptibility testing method using surface plasmon resonance.

    PubMed

    Chiang, Ya-Ling; Lin, Chi-Hung; Yen, Muh-Yong; Su, Yuan-Deng; Chen, Shean-Jen; Chen, How-Foo

    2009-03-15

    Utilizing the ultra sensitivity of surface plasmon resonance (SPR) biosensor to examine drug resistance of bacteria was studied in this research. Susceptible and resistant strains of Escherichia coli JM109 to ampicillin and those of Staphylococcus epidermidis to tetracycline, served as a blind test, were examined. The bacteria adhered on the Au thin film was treated by the injection of antibiotic flow. The optical property change of the bacteria responded to antibiotics were recorded through SPR mechanism. As a result, the susceptible strain of E. coli generally revealed more than three times of SPR angle shift when compared to the resistant one; the susceptible strain of S. epidermidis revealed irregular SPR angle shift while the resistant strain kept the SPR angle almost unchanged. The new SPR method took less than 2h of antibiotic treatment time to complete the antimicrobial susceptibility test. Different from conventional applications of SPR, specific antibodies is not required in this method. As compared to the conventional assays, Kirby-Bauer disk diffusion and variations of broth microdilution usually take 1 day to weeks to issue the report. Using this SPR assay can greatly reduce the waiting period for laboratory tests, and can therefore benefit patients who need proper antibiotic treatments to control bacterial infections. The sensitivity of the SPR biosensor built for the application is around 1.4 x 10(-4) on the refractive index.

  5. Nonweekend schedule for BACTEC drug susceptibility testing of Mycobacterium tuberculosis.

    PubMed Central

    Hawkins, J E

    1986-01-01

    Determination of the drug susceptibility of Mycobacterium tuberculosis by conventional methods using an agar-based medium may take 3 weeks or more to complete. On the other hand, results on positive cultures are generally available in 4 to 7 days with the radiometric (BACTEC, Johnston Laboratories, Towson, Md.) procedure. One disadvantage to the latter is the requirement to determine the quantity of 14CO2 in each test vial on a daily basis from the day of inoculation. Growth index readings often must be made over weekends, adding to the work load of clinical laboratories during periods of reduced staff or necessitating compensatory pay or time. Susceptibility tests with streptomycin, isoniazid, ethambutol, and rifampin against 104 M. tuberculosis strains were performed by the submerged disk method, the recommended BACTEC method with daily growth index readings, and the radiometric procedure with readings delayed for 2 days after inoculation. Criteria for interpretation of "delayed" tests were established. Drug concentrations tested included some modifications of those available commercially. Overall agreement for the four drugs by the three methods was greater than 90%. We conclude that under our test conditions a schedule of inoculation of radiometric test vials on Friday with growth index readings commencing on Monday gives susceptibility results that correlate well with the daily BACTEC method and with a conventional 7H10 agar method. PMID:3086371

  6. Radiated Susceptibility Tests in Thermal Vacuum Chambers for Space Systems

    NASA Astrophysics Data System (ADS)

    Anon Cancela, Manuel; Hernandez-Gomez, Daniel; Vazquez-Pascual, Mercedes; Lopez-Sanz, Daniel

    2016-05-01

    INTA EMC Area has a wide experience in performing Radiated Susceptibility (RS) tests according to civilian, military and aeronautical standards in Mode Tuned Chambers (MTC) for national and international projects; besides, INTA has two Thermal Vacuum Chamber (TVC) facilities in service for Space Systems tests. In order to perform RS tests to Space Systems in a more realistic environment, INTA EMC Area has stablished an internal research program to develop a procedure to perform this kind of tests inside a TVC as a Mode Tuned Chamber (MTC). In this paper the results of the TVC-04 validation measurements as a MTC are presented.

  7. Genetic susceptibility testing for neurodegenerative diseases: Ethical and practice issues

    PubMed Central

    Roberts, J. Scott; Uhlmann, Wendy R.

    2013-01-01

    As the genetics of neurodegenerative disease become better understood, opportunities for genetic susceptibility testing for at-risk individuals will increase. Such testing raises important ethical and practice issues related to test access, informed consent, risk estimation and communication, return of results, and policies to prevent genetic discrimination. The advent of direct-to-consumer genetic susceptibility testing for various neurodegenerative disorders (including Alzheimer’s disease, Parkinson’s disease, and certain prion diseases) means that ethical and practical challenges must be faced not only in traditional research and clinical settings, but also in broader society. This review addresses several topics relevant to the development and implementation of genetic susceptibility tests across research, clinical, and consumer settings; these include appropriate indications for testing, the implications of different methods for disclosing test results, clinical versus personal utility of risk information, psychological and behavioral responses to test results, testing of minors, genetic discrimination, and ethical dilemmas posed by whole-genome sequencing. We also identify future areas of likely growth in the field, including pharmacogenomics and genetic screening for individuals considering or engaged in activities that pose elevated risk of brain injury (e.g., football players, military personnel). APOE gene testing for risk of Alzheimer’s disease is used throughout as an instructive case example, drawing upon the authors’ experience as investigators in a series of multisite randomized clinical trials that have examined the impact of disclosing APOE genotype status to interested individuals (e.g., first-degree relatives, persons with mild cognitive impairment). PMID:23583530

  8. Radiated Susceptibility Test Procedure and Setup Exploiting Crosstalk

    NASA Astrophysics Data System (ADS)

    Grassi, F.; Pignari, S. A.; Spadacini, G.; Bisognin, P.; Pelissou, P.; Marra, S.

    2016-05-01

    In this work, basic principles of an alternative test procedure exploiting crosstalk to reproduce in the terminal loads of a wiring structure the same disturbances that would be induced by traditional radiated susceptibility (RS) tests are presented. Equivalence with radiation is achieved by the use of a generator circuit properly fed with two synchronized RF generators, and holds for whatever loads (even not linear) connected to the terminations of the cable harness. The proposed procedure is here tailored to the specific conditions of incidence foreseen by aerospace Standards on RS. Its effectiveness is validated by measurements carried out in an ad hoc test setup.

  9. Bacterial Nanoscale Cultures for Phenotypic Multiplexed Antibiotic Susceptibility Testing

    PubMed Central

    Weibull, Emilie; Antypas, Haris; Kjäll, Peter; Brauner, Annelie; Andersson-Svahn, Helene

    2014-01-01

    An optimal antimicrobial drug regimen is the key to successful clinical outcomes of bacterial infections. To direct the choice of antibiotic, access to fast and precise antibiotic susceptibility profiling of the infecting bacteria is critical. We have developed a high-throughput nanowell antibiotic susceptibility testing (AST) device for direct, multiplexed analysis. By processing in real time the optical recordings of nanoscale cultures of reference and clinical uropathogenic Escherichia coli strains with a mathematical algorithm, the time point when growth shifts from lag phase to early logarithmic phase (Tlag) was identified for each of the several hundreds of cultures tested. Based on Tlag, the MIC could be defined within 4 h. Heatmap presentation of data from this high-throughput analysis allowed multiple resistance patterns to be differentiated at a glance. With a possibility to enhance multiplexing capacity, this device serves as a high-throughput diagnostic tool that rapidly aids clinicians in prescribing the optimal antibiotic therapy. PMID:24989602

  10. Development of Rifapentine Susceptibility Tests for Mycobacterium tuberculosis

    PubMed Central

    Heifets, L.; Sanchez, T.; Vanderkolk, J.; Pham, V.

    1999-01-01

    Two methods for testing the susceptibility of Mycobacterium tuberculosis to rifapentine have been developed: the agar proportion method and the radiometric BACTEC technique. A critical concentration of 0.5 μg of rifapentine per ml is proposed for both methods since it provides a reliable means of distinguishing between susceptible and resistant M. tuberculosis isolates. It is recommended that two quality control M. tuberculosis strains be used at the introduction of these tests in a clinical laboratory: one that is pansusceptible (H37Rv) and one that is resistant to rifapentine. The resistant strain can be obtained from the American Type Culture Collection, where it is deposited under the number ATCC 700457. PMID:9869560

  11. Frost Susceptibility of Soil, Review of Index Tests,

    DTIC Science & Technology

    1981-12-01

    ADA111 752 COLD REGIONS RESEARCH AND ENGINEERING LAB HANOVER NH F/$ 8/13 FROST SUSCEPTIBILITY OF SOIL, REVIEW OF INDEX TESTS,(U) DEC 81 E J...ADMINISTRATION FEDERAL AVIATION ADMINISTRATION OFFICE OF THE CHIEF OF ENGINEERS By UNITED STATES ARMY CORPS OF ENGINEERS COLD) REGIONS RESEARCH AND...Development December 1981 Service) and 13. NUMBER OF PAGES Federal Highway Administration (Office of Research ) 121 Washineton. D.C. 20590 14. MONITORING

  12. Susceptibility testing for bovine respiratory and enteric disease.

    PubMed

    Apley, Michael D

    2003-11-01

    The interpretation of susceptibility results for antimicrobials with NCCLS-approved veterinary-specific breakpoints and where the methods also were NCCLS-approved are well established. When these same breakpoints are applied to other applications, however, the interpretation is not so clear. In these cases, a finding of S based on serial-dilution breakpoints puts the isolate in a defined population of bacteria with an MIC equal to or below the S breakpoint. An R result, in these cases, indicates that the organism may have an MIC equal to or greater (with no limits) than the R breakpoint. Extended-dilution testing yields more specific information about the isolate MIC. The relationship of disk-diffusion zone diameters to serial-dilution MICs is correlated on the basis of specific bacterial populations. When disk-diffusion results are interpreted for isolates other than those used for interpretive criteria development, the clinician is left wondering if the zone-diameter results now have a different relationship to serial-dilution results. Furthermore, the question of predictive value of the serial-dilution break-points still remains. The veterinary clinician should be aware of the differences in susceptibility testing predictive value for different applications. When approved veterinary-specific interpretive criteria are not available, then it is appropriate to keep records of clinical response related to susceptibility testing results for common therapies. Advice should be sought on the relationship of pathogen MICs to pharmacokinetic-pharmacodynamic parameters in these situations.

  13. 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

  14. ATPD-2354 Revision 10 Verification Test, Disc Brake Version Only (16 NOV 06) Article Test of High Mobility Multipurpose Wheeled Vehicle (HMMWV-ECV)

    DTIC Science & Technology

    2007-05-23

    standard measuring caliper . Close brake pad dimension tolerances are critical to ensuring proper brake operation. 4.1.5.1. The analysis of results...070169 ATPD-2354 REVISION 10 VERIFICATION TEST, DISC BRAKE VERSION ONLY (16 NOV 06) ARTICLE TEST OF HIGH MOBILITY MULTIPURPOSE WHEELED...Verification Test, Disc Brake Verson Only (16 NOV 06) Article Test of High Mobility Multipurpose Wheeled Vehicle (HMMWV-ECV) 5a. CONTRACT NUMBER

  15. A multiplexed microfluidic platform for rapid antibiotic susceptibility testing.

    PubMed

    Mohan, Ritika; Mukherjee, Arnab; Sevgen, Selami E; Sanpitakseree, Chotitath; Lee, Jaebum; Schroeder, Charles M; Kenis, Paul J A

    2013-11-15

    Effective treatment of clinical infections is critically dependent on the ability to rapidly screen patient samples to identify antibiograms of infecting pathogens. Existing methods for antibiotic susceptibility testing suffer from several disadvantages, including long turnaround times, excess sample and reagent consumption, poor detection sensitivity, and limited combinatorial capabilities. Unfortunately, these factors preclude the timely administration of appropriate antibiotics, complicating management of infections and exacerbating the development of antibiotic resistance. Here, we seek to address these issues by developing a microfluidic platform that relies on fluorescence detection of bacteria that express green fluorescent protein for highly sensitive and rapid antibiotic susceptibility testing. This platform possesses several advantages compared to conventional methods: (1) analysis of antibiotic action in two to four hours, (2) enhanced detection sensitivity (≈ 1 cell), (3) minimal consumption of cell samples and antibiotic reagents (<6 µL), and (4) improved portability through the implementation of normally closed valves. We employed this platform to quantify the effects of four antibiotics (ampicillin, cefalexin, chloramphenicol, tetracycline) and their combinations on Escherichia coli. Within four hours, the susceptibility of bacteria to antibiotics can be determined by detecting variations in maxima of local fluorescence intensity over time. As expected, cell density is a major determinant of antibiotic efficacy. Our results also revealed that combinations of three or more antibiotics are not necessarily better for eradicating pathogens compared to pairs of antibiotics. Overall, this microfluidic based biosensor technology has the potential to provide rapid and precise guidance in clinical therapies by identifying the antibiograms of pathogens.

  16. [Rapid test for detection of susceptibility to cefotaxime in Enterobacteriaceae].

    PubMed

    Jiménez-Guerra, Gemma; Hoyos-Mallecot, Yannik; Rodríguez-Granger, Javier; Navarro-Marí, José María; Gutiérrez-Fernández, José

    In this work an "in house" rapid test based on the change in pH that is due to hydrolysis for detecting Enterobacteriaceae susceptible to cefotaxime is evaluated. The strains of Enterobacteriaceae from 1947 urine cultures were assessed using MicroScan panels and the "in house" test. This rapid test includes red phenol solution and cefotaxime. Using MicroScan panels, 499 Enterobacteriaceae isolates were evaluated, which included 27 isolates of Escherichia coli producing extended-spectrum beta-lactamases (ESBL), 16 isolates of Klebsiella pneumoniae ESBL and 1 isolate of Klebsiella oxytoca ESBL. The "in house" test offers the following values: sensitivity 98% and specificity 97%, with negative predictive value 100% and positive predictive value 78%. The "in house" test based on the change of pH is useful in our area for detecting presumptively cefotaxime-resistant Enterobacteriaceae strains.

  17. Preparation of a blood culture pellet for rapid bacterial identification and antibiotic susceptibility testing.

    PubMed

    Croxatto, Antony; Prod'hom, Guy; Durussel, Christian; Greub, Gilbert

    2014-10-15

    Bloodstream infections and sepsis are a major cause of morbidity and mortality. The successful outcome of patients suffering from bacteremia depends on a rapid identification of the infectious agent to guide optimal antibiotic treatment. The analysis of Gram stains from positive blood culture can be rapidly conducted and already significantly impact the antibiotic regimen. However, the accurate identification of the infectious agent is still required to establish the optimal targeted treatment. We present here a simple and fast bacterial pellet preparation from a positive blood culture that can be used as a sample for several essential downstream applications such as identification by MALDI-TOF MS, antibiotic susceptibility testing (AST) by disc diffusion assay or automated AST systems and by automated PCR-based diagnostic testing. The performance of these different identification and AST systems applied directly on the blood culture bacterial pellets is very similar to the performance normally obtained from isolated colonies grown on agar plates. Compared to conventional approaches, the rapid acquisition of a bacterial pellet significantly reduces the time to report both identification and AST. Thus, following blood culture positivity, identification by MALDI-TOF can be reported within less than 1 hr whereas results of AST by automated AST systems or disc diffusion assays within 8 to 18 hr, respectively. Similarly, the results of a rapid PCR-based assay can be communicated to the clinicians less than 2 hr following the report of a bacteremia. Together, these results demonstrate that the rapid preparation of a blood culture bacterial pellet has a significant impact on the identification and AST turnaround time and thus on the successful outcome of patients suffering from bloodstream infections.

  18. Preparation of a Blood Culture Pellet for Rapid Bacterial Identification and Antibiotic Susceptibility Testing

    PubMed Central

    Croxatto, Antony; Prod'hom, Guy; Durussel, Christian; Greub, Gilbert

    2014-01-01

    Bloodstream infections and sepsis are a major cause of morbidity and mortality. The successful outcome of patients suffering from bacteremia depends on a rapid identification of the infectious agent to guide optimal antibiotic treatment. The analysis of Gram stains from positive blood culture can be rapidly conducted and already significantly impact the antibiotic regimen. However, the accurate identification of the infectious agent is still required to establish the optimal targeted treatment. We present here a simple and fast bacterial pellet preparation from a positive blood culture that can be used as a sample for several essential downstream applications such as identification by MALDI-TOF MS, antibiotic susceptibility testing (AST) by disc diffusion assay or automated AST systems and by automated PCR-based diagnostic testing. The performance of these different identification and AST systems applied directly on the blood culture bacterial pellets is very similar to the performance normally obtained from isolated colonies grown on agar plates. Compared to conventional approaches, the rapid acquisition of a bacterial pellet significantly reduces the time to report both identification and AST. Thus, following blood culture positivity, identification by MALDI-TOF can be reported within less than 1 hr whereas results of AST by automated AST systems or disc diffusion assays within 8 to 18 hr, respectively. Similarly, the results of a rapid PCR-based assay can be communicated to the clinicians less than 2 hr following the report of a bacteremia. Together, these results demonstrate that the rapid preparation of a blood culture bacterial pellet has a significant impact on the identification and AST turnaround time and thus on the successful outcome of patients suffering from bloodstream infections. PMID:25350577

  19. Rolling contact fatigue of surface modified 440C using a 'Ge-Polymet' type disc rod test rig

    NASA Technical Reports Server (NTRS)

    Thom, Robert L.

    1989-01-01

    Through hardened 440 C martensitic stainless steel test specimens were surface modified and tested for changes in rolling contact fatigue using a disc on rod test rig. The surface modifications consisted of nitrogen, boron, titanium, chromium, tantalum, carbon, or molybdenum ion implantation at various ion fluences and energies. Tests were also performed on specimens reactively sputtered with titanium nitride.

  20. Localized strain measurements of the intervertebral disc annulus during biaxial tensile testing.

    PubMed

    Karakolis, Thomas; Callaghan, Jack P

    2015-01-01

    Both inter-lamellar and intra-lamellar failures of the annulus have been described as potential modes of disc herniation. Attempts to characterize initial lamellar failure of the annulus have involved tensile testing of small tissue samples. The purpose of this study was to evaluate a method of measuring local surface strains through image analysis of a tensile test conducted on an isolated sample of annular tissue in order to enhance future studies of intervertebral disc failure. An annulus tissue sample was biaxial strained to 10%. High-resolution images captured the tissue surface throughout testing. Three test conditions were evaluated: submerged, non-submerged and marker. Surface strains were calculated for the two non-marker conditions based on motion of virtual tracking points. Tracking algorithm parameters (grid resolution and template size) were varied to determine the effect on estimated strains. Accuracy of point tracking was assessed through a comparison of the non-marker conditions to a condition involving markers placed on tissue surface. Grid resolution had a larger effect on local strain than template size. Average local strain error ranged from 3% to 9.25% and 0.1% to 2.0%, for the non-submerged and submerged conditions, respectively. Local strain estimation has a relatively high potential for error. Submerging the tissue provided superior strain estimates.

  1. Fracturing and Failure Behavior of Carrara Marble in Quasistatic and Dynamic Brazilian Disc Tests

    NASA Astrophysics Data System (ADS)

    Wong, Louis Ngai Yuen; Zou, Chunjiang; Cheng, Yi

    2014-07-01

    The tensile strength and fracturing behavior of Carrara marble subjected to the dynamic Brazilian disc test using the split Hopkinson pressure bar technique are determined and compared with those obtained by the conventional quasistatic Brazilian disc test. Detailed observation of the cracking processes is aided by high-speed video footage captured at a frame rate of 100,000 frames per second. The dynamic increase factor is computed, revealing a strong strain rate dependence of the Carrara marble when subjected to strain rates above 1 s-1. Similar to the quasistatic loading tests, conspicuous white zones/patches commonly appear prior to the initiation of visible cracks in the dynamic loading tests. Identification of the white patch initiation and evolution is aided by image comparison software. Comparing the cracking and failure processes under quasistatic and dynamic loading, some distinct differences in the white patch geometry and initiation load are observed. In addition, the extent of the compressive failure zones around the contact points between the loading platens and specimens is found to increase with the strain rate.

  2. Development of a national EUCAST challenge panel for antimicrobial susceptibility testing.

    PubMed

    Desmet, S; Verhaegen, J; Glupzcynski, Y; Van Eldere, J; Melin, P; Goossens, H; Piérard, D; Declercq, P; Lagrou, K; Boel, A; Cartuyvels, R; Denis, O; Vandewal, W; Saegeman, V

    2016-08-01

    A challenge panel of bacterial strains useful for clinical laboratories to validate their European Committee on Antimicrobial Susceptibility Testing (EUCAST) antimicrobial susceptibility test (AST) system was established. A total of 117 strains, obtained from Belgian Reference Centres (n = 57) and from routine clinical samples (n = 60) was selected based on resistance pattern. These strains were analysed in seven different laboratories by three different automated AST systems (Vitek (n = 2), Phoenix (n = 2) and Microscan (n = 2)) and by disc diffusion from five different manufacturers (Rosco (n = 2), Becton-Dickinson (n = 2), Biomérieux (n = 1), Bio-rad (n = 1) and i2a (n = 1)). To select the challenge panel, selection criteria were set for categorical agreement between the different systems and the number of very major errors, major errors and minor errors. Very major and major errors for at least two antibiotics were observed in 43% of all strains, leading to the exclusion of these strains from the selected panel. In only 10% of all tested strains was there 100% categorical agreement for all antibiotics. Finally, 28 strains (14 Gram-positive and 14 Gram-negative) covering a wide spectrum of resistance mechanisms were selected. Pilot-testing of this challenge panel in 20 laboratories mainly confirmed the results of the validation study. Only six strains withheld for the pilot study could not be used as challenge strain due to an overall (very) major error rate of >5% for a particular antibiotic (n = 5) or for two antibiotics (n = 1). To conclude, this challenge panel should facilitate the implementation and use of EUCAST breakpoints in laboratories.

  3. In Vitro Susceptibility Testing of Bedaquiline against Mycobacterium avium Complex.

    PubMed

    Brown-Elliott, Barbara A; Philley, Julie V; Griffith, David E; Thakkar, Foram; Wallace, Richard J

    2017-02-01

    We performed bedaquiline broth microdilution susceptibility testing using Clinical and Laboratory Standards Institute (CLSI) guidelines on 103 respiratory isolates of Mycobacterium avium complex (MAC), including multidrug-resistant isolates. Approximately 90% of isolates had bedaquiline MICs of ≤0.008 μg/ml, and 102/103 isolates had MICs of ≤0.015 μg/ml. Bedaquiline has excellent potential for use in patients with MAC infections, although for reasons of its metabolism by the cytochrome P450 system, it should not be given with rifampin.

  4. Chemically defined antimicrobial susceptibility test medium for Pseudomonas aeruginosa.

    PubMed

    Jorgensen, J H; Lee, J C; Jones, P M

    1977-03-01

    A chemically defined growth medium containing physiological concentrations of magnesium and calcium ions was utilized in a microdilution procedure for antimicrobial drug susceptibility testing of Pseudomonas aeruginosa. Determinations of growth end points were simplified by use of sodium citrate as a sole carbon source and bromothymol blue as a pH indicator. Growth of the test organisms was detectable by a change in the indicator color from green to blue after alkalinization of the medium due to citrate utilization. Minimal inhibitory concentrations of amikacin, carbenicillin, gentamicin, and tobramycin were determined on 100 recent clinical isolates of Pseudomonas. Parallel determinations using the microdilution procedure and a conventional tube-broth dilution technique incorporating Mueller-Hinton broth with identical magnesium and calcium content generally agreed within one twofold dilution. Modal minimal inhibitory concentrations for susceptible strains using the microdilution method were: amikacin, 6 mug/ml; carbenicillin, 50 mug/ml; gentamicin, 1.5 mug/ml; tobramycin, 1.5 mug/ml. This modified microdilution technique allowed rapid, definitive minimal inhibitory concentration determinations, using growth end points defined by a color indicator change.

  5. Collaborative Evaluation of Optimal Antifungal Susceptibility Testing Conditions for Dermatophytes

    PubMed Central

    Fernández-Torres, Belkys; Cabañes, Francisco J.; Carrillo-Muñoz, Alfonso J.; Esteban, Alexandre; Inza, Isabel; Abarca, Lourdes; Guarro, Josep

    2002-01-01

    A multicenter study was conducted to define the most suitable testing conditions for antifungal susceptibility of dermatophytes. Broth microdilution MICs of clotrimazole, itraconazole, and terbinafine were determined in three centers against 60 strains of dermatophytes. The effects of inoculum density (ca. 103 and 104 CFU/ml), incubation time (3, 7, and 14 days), endpoint criteria for MIC determination (complete [MIC-0] and prominent [MIC-2] growth inhibition), and incubation temperature (28 and 37°C) on intra- and interlaboratory agreement were analyzed. The optimal testing conditions identified were an inoculum of 104 CFU/ml, a temperature of incubation of 28°C, an incubation period of 7 days, and MIC-0. PMID:12409365

  6. Equilibrium star formation in a constant Q disc: model optimization and initial tests

    NASA Astrophysics Data System (ADS)

    Zheng, Zheng; Meurer, Gerhardt R.; Heckman, Timothy M.; Thilker, David A.; Zwaan, Martin A.

    2013-10-01

    We develop a model for the distribution of the interstellar medium (ISM) and star formation in galaxies based on recent studies that indicate that galactic discs stabilize to a constant stability parameter, which we combine with prescriptions of how the phases of the ISM are determined and for the star formation law (SFL). The model predicts the gas surface mass density and star formation intensity of a galaxy given its rotation curve, stellar surface mass density and the gas velocity dispersion. This model is tested on radial profiles of neutral and molecular ISM surface mass density and star formation intensity of 12 galaxies selected from the H I Nearby Galaxy Survey sample. Our tests focus on intermediate radii (0.3 to 1 times the optical radius) because there are insufficient data to test the outer discs and the fits are less accurate in detail in the centre. Nevertheless, the model produces reasonable agreement with the ISM mass and star formation rate integrated over the central region in all but one case. To optimize the model, we evaluate four recipes for the stability parameter, three recipes for apportioning the ISM into molecular and neutral components, and eight versions of the SFL. We find no clear-cut best prescription for the two-fluid (gas and stars) stability parameter Q2f and therefore for simplicity, we use the Wang and Silk approximation (QWS). We found that an empirical scaling between the molecular-to-neutral ISM ratio (Rmol) and the stellar surface mass density proposed by Leroy et al. works marginally better than the other two prescriptions for this ratio in predicting the ISM profiles, and noticeably better in predicting the star formation intensity from the ISM profiles produced by our model with the SFLs we tested. Thus, in the context of our modelled ISM profiles, the linear molecular SFL and the two-component SFL work better than the other prescriptions we tested. We incorporate these relations into our `constant Q disc' model.

  7. OT1_bmatthew_4: Testing Planetary Dynamics and Evolutionary History in the HR 8799 Planet/Disc System

    NASA Astrophysics Data System (ADS)

    Matthews, B.

    2010-07-01

    We propose to map the debris disc associated with the multi-planet system HR 8799 in order to constrain the current dynamical state of the planetary system and refine models for dust production in the disc, thereby testing models for the origins of the three known giant planets. Herschel's sensitivity and resolution make it possible to image both the cold planetesimal disc (posited to lie between radii of 90-300 AU) as well as the fainter extended halo (300 - 1000 AU radius) at multiple wavelengths. Direct detection of the edges of the cold belt of dust and an independent measure of the system's inclination will provide critical constraints on models of the planetary orbits within the system, particularly for the outer-most planet for which mass and orbit information can be constrained by simultaneous fits to the planet and disc. The combination of three massive, coeval, and spectroscopically characterizable planets, together with the dust disc, makes this system a "Rosetta Stone" for planet formation studies. The disc is also important for differentiating between planet formation scenarios. Models predict variations in resonance structure for migration versus in situ formation, and multi-wavelength variations in observed structure within Herschel's wavelength range in the case of planetary migration. This proposal is at the very heart of Herschel's top science goal of understanding the mechanisms involved in the formation of stars and planetary bodies. The resolution, sensitivity and multi-wavelength imaging of Herschel are crucial to this program.

  8. DVD technology-based molecular diagnosis platform: quantitative pregnancy test on a disc.

    PubMed

    Li, Xiaochun; Weng, Samuel; Ge, Bixia; Yao, Zhihui; Yu, Hua-Zhong

    2014-05-21

    A diagnosis platform based entirely on DVD technology was developed for on-site quantitation of molecular analytes of interest, e.g., human chorionic gonadotropin (hCG) in urine samples ("quantitative pregnancy test on a disc"). An hCG-specific monoclonal antibody-binding assay prepared on a regular DVD-R was labeled with nanogold-streptavidin conjugates for signal enhancement with a customized silver-staining protocol. An unmodified, conventional computer optical drive was used for assay reading, and free disc-quality analysis software for data processing. The performance (sensitivity and selectivity) of this DVD assay is comparable to that of well-established colorimetric methods (determination of optical darkness ratios) and standard enzyme-linked immunosorbent assays (ELISA). As validated by examining its linear correlation with the ELISA results on the same set of samples, the DVD assay promises to be a low-cost, multiplex, point-of-care (POC) diagnostic tool for physicians and even for individuals at home, producing prompt results.

  9. Reliability of the Kirby-Bauer disc diffusion method for detecting methicillin-resistant strains of Staphylococcus aureus.

    PubMed

    Drew, W L; Barry, A L; O'Toole, R; Sherris, J C

    1972-08-01

    The resistance of Staphylococcus aureus to methicillin and related drugs can be reliably determined by using the Kirby-Bauer method of susceptibility testing if the incubation temperature is 35 C or below, but resistance may be missed at 37 C. The 1-mug discs of oxacillin and nafcillin or the 5-mug discs of methicillin may be used for this purpose but not the 1-mug discs of cloxacillin. The latter fail to discriminate between sensitive and resistant staphylococci by zone measurement; some resistant strains of staphylococci may show larger zones of inhibition than sensitive strains. Stability of these antibiotic-containing discs was studied under conditions of temperature and humidity variation that might be encountered in a clinical laboratory refrigerator. Oxacillin discs were the most stable and are to be preferred for susceptibility testing. Nafcillin discs were less stable, and methicillin discs lose their potency rapidly unless carefully stored in a refrigerator with a desiccant.

  10. A New Approach for Pyrazinamide Susceptibility Testing in Mycobacterium tuberculosis

    PubMed Central

    Loli, Sebastian; Gilman, Robert H.; Gutierrez, Andrés; Fuentes, Patricia; Cotrina, Milagros; Kirwan, Daniela; Sheen, Patricia

    2012-01-01

    Background: Pyrazinamide (PZA) is an important drug in the treatment of tuberculosis. Microbiological methods of PZA susceptibility testing are controversial and have low reproducibility. After conversion of PZA into pyrazinoic acid (POA) by the bacterial pyrazinamidase enzyme, the drug is expelled from the bacteria by an efflux pump. Objective: To evaluate the rate of POA extrusion from Mycobacterium tuberculosis as a parameter to detect PZA resistance. Methods: The rate of POA extrusion and PZA susceptibility determined by BACTEC 460 were measured for 34 strains in a previous study. PZA resistance was modeled in a logistic regression with the pyrazinoic efflux rate. Result: POA efflux rate predicted PZA resistance with 70.83%–92.85% sensitivity and 100% specificity compared with BACTEC 460. Conclusion: POA efflux rate could be a useful tool for predicting PZA resistance in M. tuberculosis. Further exploration of this approach may lead to the development of new tools for diagnosing PZA resistance, which may be of public health importance. PMID:22372927

  11. Laboratory tests to study the influence of rock stress confinement on the performances of TBM discs in tunnels

    NASA Astrophysics Data System (ADS)

    Innaurato, N.; Oggeri, C.; Oreste, P.; Vinai, R.

    2011-06-01

    To clarify some aspects of rock destruction with a disc acting on a high confined tunnel face, a series of tests were carried out to examine fracture mechanisms under an indenter that simulates the tunnel boring machine (TBM) tool action, in the presence of an adjacent groove, when a state of stress (lateral confinement) is imposed on a rock sample. These tests proved the importance of carefully establishing the optimal distance of grooves produced by discs acting on a confined surface, and the value (as a mere order of magnitude) of the increase of the thrust to produce the initiation of chip formation, as long as the confinement pressure becomes greater.

  12. Everlasting sliding-disc valve. METC SOA test valve No. B-3, State-of-the-art lockhopper valve testing and development project. Summary test report

    SciTech Connect

    Gardner, J.F.; Hall, R.C.; Hornbeck, R.G.; Griffith, R.A.; Yost, T.M.; Harvey, D.M.; Galvin, W.E.; Gayheart, T.R.; Kapur, S.K.

    1980-08-01

    The Everlasting Sliding-Disc Valve (METC SOA Test Valve No. B-3) accumulated 740 valve cycles in the Valve Static Test Unit and over 16,000 valve cycles in the Valve Dynamic Test Unit. Only minor operating problems, primarily erratic motion and some scoring of the seating surface, where encountered with coarse limestone (5/16'' x 1/8'') particles. Operation with fine solids (100-mesh limestone) showed excellent performance. The actuator level arm failed twice but a change in clearances solved the problem. Based on its performance in testing, the Everlastinc Sliding-Disc Valve, with minor modifications, is a very promising choice for feedside lockhopper service in coal conversion and utilization.

  13. High-Throughput Intracellular Antimicrobial Susceptibility Testing of Legionella pneumophila

    PubMed Central

    Chiaraviglio, Lucius

    2015-01-01

    Legionella pneumophila is a Gram-negative opportunistic human pathogen that causes a severe pneumonia known as Legionnaires' disease. Notably, in the human host, the organism is believed to replicate solely within an intracellular compartment, predominantly within pulmonary macrophages. Consequently, successful therapy is predicated on antimicrobials penetrating into this intracellular growth niche. However, standard antimicrobial susceptibility testing methods test solely for extracellular growth inhibition. Here, we make use of a high-throughput assay to characterize intracellular growth inhibition activity of known antimicrobials. For select antimicrobials, high-resolution dose-response analysis was then performed to characterize and compare activity levels in both macrophage infection and axenic growth assays. Results support the superiority of several classes of nonpolar antimicrobials in abrogating intracellular growth. Importantly, our assay results show excellent correlations with prior clinical observations of antimicrobial efficacy. Furthermore, we also show the applicability of high-throughput automation to two- and three-dimensional synergy testing. High-resolution isocontour isobolograms provide in vitro support for specific combination antimicrobial therapy. Taken together, findings suggest that high-throughput screening technology may be successfully applied to identify and characterize antimicrobials that target bacterial pathogens that make use of an intracellular growth niche. PMID:26392509

  14. Echinocandin Resistance, Susceptibility Testing and Prophylaxis: Implications for Patient Management

    PubMed Central

    Perlin, David S.

    2014-01-01

    This article addresses the emergence of echinocandin resistance among Candida species, mechanisms of resistance, factors that promote resistance and confounding issues surrounding standard susceptibility testing. Fungal infections remain a significant cause of global morbidity and mortality, especially among patients with underlying immunosupression. Antifungal therapy is a critical component of patient management for acute and chronic diseases. Yet, therapeutic choices are limited due to only a few drug classes available to treat systemic disease. Moreover, the problem is exacerbated by the emergence of antifungal resistance, which has resulted in difficult to manage multidrug resistant strains. Echinocandin drugs are now the preferred choice to treat a range of candidiasis. These drugs target and inhibit the fungal-specific enzyme glucan synthase, which is responsible for the biosynthesis of a key cell wall polymer. Therapeutic failures involving acquisition of resistance among susceptible organisms like Candida albicans is largely a rare event. However, in recent years, there is an alarming trend of increased resistance among strains of Candida glabrata, which in many cases are also resistant to azole drugs. Echinocandin resistance is always acquired during therapy and the mechanism of resistance is well established to involve amino acid changes in “hot-spot regions of the Fks subunits carrying the catalytic portion of glucan synthase. These changes significantly decrease the sensitivity of the enzyme to drug resulting in higher MIC values. A range of drug responses, from complete to partial refractory response, is observed depending on the nature of the amino acid substitution, and clinical responses are recapitulated in pharmacodynamic models of infection. The cellular processes promoting the formation of resistant Fks strains involve complex stress response pathways, which yield a variety of adaptive compensatory genetic responses. Stress-adapted cells

  15. Evaluation of the Kirby-Bauer disc diffusion test as a screening test for high-level aminoglycoside resistance in enterococci.

    PubMed

    Pfaller, M A; Niles, A C; Murray, P R

    1984-10-01

    The Kirby-Bauer disc diffusion test was evaluated as a test to detect high-level aminoglycoside (streptomycin, kanamycin, tobramycin, and gentamicin) resistance in isolates of enterococci. The authors found that high-level resistance could not be predicted accurately with the diffusion test.

  16. Drug susceptibility testing of Mycobacterium tuberculosis with nitrate reductase assay.

    PubMed

    Coban, Ahmet Yilmaz; Birinci, Asuman; Ekinci, Bora; Durupinar, Belma

    2004-09-01

    The nitrate reductase assay (NRA) was evaluated for susceptibility testing of Mycobacterium tuberculosis using 80 clinical isolates of M. tuberculosis and H37Rv as a control strain. All isolates were tested by the proportion method and the NRA for isoniazid (INH), rifampicin (RIF), streptomycin (STR) and ethambutol (ETM). The proportion method was carried out according to NCCLS on Löwenstein-Jensen (LJ) medium and the NRA on LJ medium containing 1000 microg/ml potassium nitrate (KNO(3)). After incubation for 7, 10, 14 and 21 days, Griess reagent was added to each LJ medium and nitrate reduction was determined by a colour change. Comparing the NRA with the proportion method, sensitivities were 100, 100, 82.1 and 92.2% for INH, RIF, STR and ETM, respectively. Specificities were 100, 100, 92.3 and 100% for INH, RIF, STR and ETM, respectively. The results of 2, 22 and 56 isolates were obtained after 7, 10 and 14 days, respectively. The proportion method result were read at 21-28 days. The NRA is rapid, inexpensive and easy to perform. Our results indicated that the NRA is suitable for the early determination of INH and RIF resistance in countries where sophisticated procedures are not always available.

  17. Reevaluation of the diametral compression test for tablets using the flattened disc geometry.

    PubMed

    Mazel, V; Guerard, S; Croquelois, B; Kopp, J B; Girardot, J; Diarra, H; Busignies, V; Tchoreloff, P

    2016-11-20

    Mechanical strength is an important critical quality attribute for tablets. It is classically measured, in the pharmaceutical field, using the diametral compression test. Nevertheless, due to small contact area between the tablet and the platens, some authors suggested that during the test, the failure could occur in tension away from the center which would invalidate the test and the calculation of the tensile strength. In this study, the flattened disc geometry was used as an alternative to avoid contact problems. The diametral compression on both flattened and standard geometries was first studied using finite element method (FEM) simulation. It was found that, for the flattened geometry, both maximum tensile strain and stress were located at the center of the tablet, which was not the case for the standard geometry. Experimental observations using digital image correlation (DIC) confirmed the numerical results. The experimental tensile strength obtained using both geometries were compared and it was found that the standard geometry always gave lower tensile strength than the flattened geometry. Finally, high-speed video capture of the test made it possible to detect that for the standard geometry the crack initiation was always away from the center of the tablet.

  18. Antibacterial susceptibility of plaque bacteria.

    PubMed

    Newman, M G; Hulem, C; Colgate, J; Anselmo, C

    1979-07-01

    Selected anaerobic, capnophilic and facultative bacteria isolated from patients with various forms of periodontal health and disease were tested for their susceptibility to antibiotics and antimicrobial agents. Specific bactericidal and minimum inhibitory concentrations were compared to disc zone diameters, thereby generating new standards for the potential selection of antimicrobial agents.

  19. The biochemical characteristics of wear testing lubricants affect polyethylene wear in orthopaedic pin-on-disc testing.

    PubMed

    Guenther, Leah E; Turgeon, Thomas R; Bohm, Eric R; Brandt, Jan-M

    2015-01-01

    Lubricant protein concentration is known to affect crosslinked polyethylene wear in in vitro testing; however, the biochemical nature of these lubricants may also have a significant effect on wear and dictate its clinical relevance. A modified approach to pin-on-disc testing was implemented to explore the effect of four biochemically different lubricants on the wear of two types of crosslinked polyethylene materials (XLK™ and Marathon™; DePuy Synthes, Warsaw, IN, USA). XLK was associated with higher wear rates than Marathon. In comparison to lubricants containing deionized water, lubricants containing phosphate buffered saline solution and hyaluronic acid increased osmolality by up to 1.2 times and thermal stability by up to 1.4 times. This biochemical change reduced wear by up to 12.5 times. Wear rates for XLK and Marathon differed by a factor of 3.2 using lubricants with phosphate buffered saline solution as the dilutive media, but only 2.0 for lubricants with deionized water. Interestingly, varying the concentration of hyaluronic acid did not have a significant effect on wear, and differences between XLK and Marathon wear rates were not found to be statistically significant when hyaluronic acid was added to the lubricant. The findings of this study showed that increasing the osmolality and thermal stability of lubricants to more clinical levels decreased wear; however, the effect of hyaluronic acid on wear may not be apparent in simplistic pin-on-disc testing. It was suggested that phosphate buffered saline solution be used as the dilutive media of choice in order to better differentiate the ranking of materials while maintaining some clinical relevance.

  20. Rapid Bead-Based Antimicrobial Susceptibility Testing by Optical Diffusometry

    PubMed Central

    Chung, Chih-Yao; Wang, Jhih-Cheng; Chuang, Han-Sheng

    2016-01-01

    This study combined optical diffusometry and bead-based immunoassays to develop a novel technique for quantifying the growth of specific microorganisms and achieving rapid AST. Diffusivity rises when live bacteria attach to particles, resulting in additional energy from motile microorganisms. However, when UV-sterilized (dead) bacteria attach to particles, diffusivity declines. The experimental data are consistent with the theoretical model predicted according to the equivalent volume diameter. Using this diffusometric platform, the susceptibility of Pseudomonas aeruginosa to the antibiotic gentamicin was tested. The result suggests that the proliferation of bacteria is effectively controlled by gentamicin. This study demonstrated a sensitive (one bacterium on single particles) and time-saving (within 2 h) platform with a small sample volume (~0.5 μL) and a low initial bacteria count (50 CFU per droplet ~ 105 CFU/mL) for quantifying the growth of microorganisms depending on Brownian motion. The technique can be applied further to other bacterial strains and increase the success of treatments against infectious diseases in the near future. PMID:26863001

  1. DKG statement on the use of metal alloy discs for patch testing in suspected intolerance to metal implants.

    PubMed

    Thomas, Peter; Geier, Johannes; Dickel, Heinrich; Diepgen, Thomas; Hillen, Uwe; Kreft, Burkhard; Schnuch, Axel; Szliska, Christiane; Mahler, Vera

    2015-10-01

    Intolerance reactions to metal implants may be caused by metal allergy. However, prior to implantation, 'prophetic'/prophylactic patch testing should not be performed. Pre-implant patch testing should only be done to verify or exclude metal allergy in patients with a corresponding history. In case of implant-related complications - in particular following replacement arthroplasty - such as pain, effusion, skin lesions, reduced range of motion or implant loosening, orthopedic causes should be ruled out first. Workup of suspected metal implant allergy should then be done using the DKG standard series, which includes nickel, cobalt, and chromium preparations. Various studies assessing the usefulness of metal alloy discs for patch testing have shown this particular approach to be ineffective with respect to providing reliable information on metal allergy. Any positive reaction in such tests cannot be assigned to a specific metal contained within the alloy. Furthermore, there is a risk of broad and indiscriminate use of these readily available discs. Accordingly, given the lack of additional benefit compared to patch testing with standardized metal salt preparations, we do not recommend patch testing with metal alloy discs.

  2. Development of a new protocol for rapid bacterial identification and susceptibility testing directly from urine samples.

    PubMed

    Zboromyrska, Y; Rubio, E; Alejo, I; Vergara, A; Mons, A; Campo, I; Bosch, J; Marco, F; Vila, J

    2016-06-01

    The current gold standard method for the diagnosis of urinary tract infections (UTI) is urine culture that requires 18-48 h for the identification of the causative microorganisms and an additional 24 h until the results of antimicrobial susceptibility testing (AST) are available. The aim of this study was to shorten the time of urine sample processing by a combination of flow cytometry for screening and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) for bacterial identification followed by AST directly from urine. The study was divided into two parts. During the first part, 675 urine samples were processed by a flow cytometry device and a cut-off value of bacterial count was determined to select samples for direct identification by MALDI-TOF-MS at ≥5 × 10(6) bacteria/mL. During the second part, 163 of 1029 processed samples reached the cut-off value. The sample preparation protocol for direct identification included two centrifugation and two washing steps. Direct AST was performed by the disc diffusion method if a reliable direct identification was obtained. Direct MALDI-TOF-MS identification was performed in 140 urine samples; 125 of the samples were positive by urine culture, 12 were contaminated and 3 were negative. Reliable direct identification was obtained in 108 (86.4%) of the 125 positive samples. AST was performed in 102 identified samples, and the results were fully concordant with the routine method among 83 monomicrobial infections. In conclusion, the turnaround time of the protocol described to diagnose UTI was about 1 h for microbial identification and 18-24 h for AST.

  3. Testing the Susceptibility of GNSS Receivers to Radio Frequency Interference

    NASA Astrophysics Data System (ADS)

    Berglund, H. T.; Blume, F.; Gallaher, W. W.

    2015-12-01

    Global Navigational Satellite Systems (GNSS) receivers are employed by the scientific community for measuring a variety of geodetic, geophysical and atmospheric phenomena. Data acquisition frequently occurs in a variety of challenging environments, which include locations with high Radio Frequency (RF) noise characteristics. Tracking the relatively low powered GNSS carrier signals broadcast from space becomes even more challenging in the presence of adjacent band RF noise. The demand for terrestrial RF spectrum use for a variety of non-GNSS applications is ever increasing, which poses potential challenges for GNSS site operators who would like to acquire the highest quality data possible. In recent years, UNAVCO has observed an increase in the number of GNSS sites which are negatively impacted by RF interference. In previous work, we have shown that telemetry systems utilizing the Iridium satellite constellation can degrade GNSS data quality, as the adjacent-band (1610-1616 Mhz) signals transmitted by Iridium data transmitters are close in proximity to the L1 frequency of GNSS. The impact of RF interference from Iridium data transmitters on GNSS receivers can cause reduced Signal-to-Noise (SNR), increased cycle slips, and in worst case scenarios, prevent the receiver from tracking. To better characterize GNSS receiver susceptibility to RF interference, UNAVCO has performed a variety of tests with Continuous Wave (CW) noise sources in RF bands adjacent to the GNSS spectrum. We simulate a subset of discrete noise frequencies commonly observed in the field using a frequency generator, which supplies a signal with varying power output from a transmitter located within 1 m of the GNSS antenna. Signal power is incremented in small steps until receiver tracking fails. All receivers are simultaneously evaluated using an 8-way splitter. In addition, we investigate receiver tracking performance with a simulated increase in the RF noise floor. To analyze the results we use

  4. Anchor/Darling Double-Disc Gate Valve, METC SOA Test Valve No. A-12 and Test Valve No. A-12R state-of-the-art Lockhopper Valve-Testing and Development Project. Summary test report

    SciTech Connect

    Gardner, J.F.; Galvin, W.E.; Gayheart, T.R.; Griffith, R.A.; Hall, R.C.; Hornbeck, R.G.; Maxfield, D.A.; Nieman, H.D.; Chester, S.O.

    1981-03-01

    The Anchor/Darling Double-Disc Gate Valve (METC SOA Test Valve Nos. A-12 and A-12R) performed well in testing with clean gases. The packing developed some leakage, but it could be controlled by tightening the packing gland. In both dynamic and slurry testing, solids accumulated in the bonnet and internals, jamming the valve. The forces on internal parts as a result of the jamming were sufficient to crack the hardfacing on the seats and discs. Any design with voids that can be packed with particles will have difficulty handling solids media. It is recommended that no further testing be performed on this valve.

  5. 21 CFR 866.1700 - Culture medium for antimicrobial susceptibility tests.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Culture medium for antimicrobial susceptibility tests. 866.1700 Section 866.1700 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND....1700 Culture medium for antimicrobial susceptibility tests. (a) Identification. A culture medium...

  6. 21 CFR 866.1700 - Culture medium for antimicrobial susceptibility tests.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Culture medium for antimicrobial susceptibility tests. 866.1700 Section 866.1700 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND....1700 Culture medium for antimicrobial susceptibility tests. (a) Identification. A culture medium...

  7. 21 CFR 866.1700 - Culture medium for antimicrobial susceptibility tests.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Culture medium for antimicrobial susceptibility tests. 866.1700 Section 866.1700 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND....1700 Culture medium for antimicrobial susceptibility tests. (a) Identification. A culture medium...

  8. 21 CFR 866.1700 - Culture medium for antimicrobial susceptibility tests.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Culture medium for antimicrobial susceptibility tests. 866.1700 Section 866.1700 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND....1700 Culture medium for antimicrobial susceptibility tests. (a) Identification. A culture medium...

  9. 21 CFR 866.1700 - Culture medium for antimicrobial susceptibility tests.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Culture medium for antimicrobial susceptibility tests. 866.1700 Section 866.1700 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND....1700 Culture medium for antimicrobial susceptibility tests. (a) Identification. A culture medium...

  10. Preparation of ormetoprim sulfadimethoxine medicated discs for disc diffusion assay

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Romet (a blend of ormetoprim and sulfadimethoxine) is a typeA medicated article for the manufacture of medicated feed in the catfish industry. Recently, the commercial manufacture of ormetoprim–sulfadimethoxine susceptibility discs was discontinued. Ormetoprim–sulfadimethoxine discs were prepared at...

  11. Antimicrobial susceptibility testing of Spanish field isolates of Brachyspira hyodysenteriae.

    PubMed

    Hidalgo, A; Carvajal, A; García-Feliz, C; Osorio, J; Rubio, P

    2009-08-01

    This study is the first conducted in Spain to evaluate antimicrobial susceptibility of field isolates of Brachyspira hyodysenteriae. One hundred and eight isolates of the bacterium, recovered from different Spanish swine farms between 2000 and 2007, were investigated. The minimum inhibitory concentrations (MIC) of erythromycin, tylosin, tiamulin, valnemulin, clindamycin and lincomycin were determined using a broth microdilution technique. Most of the isolates showed poor susceptibility to erythromycin (MIC(90)>256 microg/ml), tylosin (MIC(90)>256 microg/ml), clindamycin (MIC(90)>4 microg/ml) and lincomycin (MIC(90)=128 microg/ml). Reduced susceptibility to tiamulin and valnemulin was observed with a MIC>2 microg/ml in 17.6% and 7.41% of the B. hyodysenteriae isolates, respectively. Moreover, a survival analysis permitted the detection of an increasing trend in the MIC values for almost all the antimicrobials used in the treatment of swine dysentery when comparing recent isolates (from 2006 to 2007) with those recovered in earlier years (between 2000 and 2004).

  12. A Novel Hypoxia Challenge Test Demonstrates Cardiovascular and Pulmonary Susceptibility to Acrolein Gas in Hypertensive Rats.

    EPA Science Inventory

    High levels of air pollution increase the risk of cardiovascular morbidity and mortality, especially in susceptible populations including those with hypertension. Stress tests are useful for manifesting latent effects of exposure, particularly at low concentrations, often when no...

  13. Validation of microscopic observation drug susceptibility testing for rapid, direct rifampicin and isoniazid drug susceptibility testing in patients receiving tuberculosis treatment.

    PubMed

    Coronel, J; Roper, M H; Herrera, C; Bonilla, C; Jave, O; Gianella, C; Sabogal, I; Huancaré, V; Leo, E; Tyas, A; Mendoza-Ticona, A; Caviedes, L; Moore, D A J

    2014-06-01

    Drug susceptibility testing (DST) is often needed in patients clinically failing tuberculosis (TB) therapy. Most studies of phenotypic direct drug susceptibility tests, such as microscopic observation drug susceptibility (MODS) tests, have been performed in patients not receiving TB treatment. The effect of ongoing TB treatment on the performance of MODS direct DST has not been previously explored, but patients failing such therapy constitute an important target group. The aim of this study was to determine the performance of MODS direct rifampicin and isoniazid DST in patients clinically failing first-line TB treatment, and to compare MODS direct DST with indirect proportion method DST. Sputa from 264 TB patients were cultured in parallel in Lowenstein-Jensen (LJ) and MODS assays; strains were tested for rifampicin and isoniazid susceptibility by the proportion method at the national reference laboratory. Ninety-three samples were culture-positive by LJ and MODS (concordance of 96%; kappa 0.92). With conventional MODS plate DST reading (performed on the same day as the sample is classified as culture-positive), the isoniazid DST concordance was 96.8% (kappa 0.89), and the concordance for rifampicin susceptibility testing was 92.6% (kappa 0.80). Reading of MODS DST plates 1 week after cultures had been determined to be culture-positive improved overall performance marginally-the isoniazid DST concordance was 95.7% (kappa 0.85); and the rifampicin DST concordance was 96.8% (kappa 0.91). Sensitivity for detection of multidrug-resistant TB was 95.8%. MODS testing provided reliable rifampicin and isoniazid DST results for samples obtained from patients receiving TB therapy. A modified DST reading schedule for such samples, with a final reading 1 week after a MODS culture turns positive, marginally improves the concordance with reference DST.

  14. Development of a rapid ATP bioluminescence assay for biocidal susceptibility testing of rapidly growing mycobacteria.

    PubMed

    Kapoor, Renuka; Yadav, Jagjit S

    2010-10-01

    An ATP-based biocide susceptibility assay for mycobacteria was developed by optimizing the cell lysis and assay conditions. Compared to the conventional agar plating method, the assay was rapid (1.5 h) and showed high sensitivity and specificity as determined by receiver operating characteristic (ROC) analysis. The test species, Mycobacterium immunogenum, M. chelonae, and M. abscessus, showed various susceptibilities to the glutaraldehyde- and isothiazolone-based test biocides.

  15. Rapid identification and antibiotic susceptibility testing of Yersinia pestis using bioluminescent reporter phage

    PubMed Central

    Schofield, David A.; Molineux, Ian J.; Westwater, Caroline

    2012-01-01

    The rapid identification and antibiotic susceptibility testing of Yersinia pestis is paramount for a positive prognosis. We previously engineered a Y. pestis-specific ‘bioluminescent’ reporter phage for the identification of Y. pestis. In this study, we generated an improved reporter phage and evaluated the ability of this phage to provide direct and rapid susceptibility testing. Compared to the first generation reporter, the second generation reporter exhibited a 100-fold increase in signal strength, leading to a 10-fold increase in assay sensitivity. Y. pestis antimicrobial testing in the presence of the reporter elicited bioluminescent signals that were drug concentration-dependent, and produced susceptibility profiles that mirrored the standard CLSI method. The phage-generated susceptibility profiles, however, were obtained within hours in contrast to days with the conventional method. PMID:22579583

  16. Rapid identification and antibiotic susceptibility testing of Yersinia pestis using bioluminescent reporter phage.

    PubMed

    Schofield, David A; Molineux, Ian J; Westwater, Caroline

    2012-08-01

    The rapid identification and antibiotic susceptibility testing of Yersinia pestis is paramount for a positive prognosis. We previously engineered a Y. pestis-specific 'bioluminescent' reporter phage for the identification of Y. pestis. In this study, we generated an improved reporter phage and evaluated the ability of this phage to provide direct and rapid susceptibility testing. Compared to the first generation reporter, the second generation reporter exhibited a 100-fold increase in signal strength, leading to a 10-fold increase in assay sensitivity. Y. pestis antimicrobial testing in the presence of the reporter elicited bioluminescent signals that were drug concentration-dependent, and produced susceptibility profiles that mirrored the standard CLSI method. The phage-generated susceptibility profiles, however, were obtained within hours in contrast to days with the conventional method.

  17. A Genetic Lung Cancer Susceptibility Test may have a Positive Effect on Smoking Cessation.

    PubMed

    Kammin, Tammy; Fenton, Andrew K; Thirlaway, Kathryn

    2015-06-01

    Smoking increases the risk of developing lung cancer. Genetic loci have been identified which could form the basis of a lung cancer susceptibility test; but little is known whether such a test would interest or motivate those trying to quit smoking. To address this, we investigated the attitudes of people trying to quit smoking towards genetic susceptibility testing for lung cancer. Participant's attitudes to topics associated with lung cancer susceptibility testing were assessed; were they interested in genetic testing? What impact would a hypothetical high- or low- risk result have on smoking cessation? 680 self-completion questionnaires were given to individuals attending National Health Service stop smoking clinics in three different areas of the United Kingdom between 2011 and 2012. 139 questionnaires were returned, giving a 20 % response rate. Participants expressed an interest in a genetic susceptibility test for lung cancer and almost all reported that a high-risk result would increase their motivation to stop smoking. However, many participants had a neutral attitude towards a low-risk result. Most participants agreed their smoking habit could lead to lung cancer. Lung cancer susceptibility testing may be a useful incentive to help people quit smoking. This study suggests the need for genetic services to work with smoking cessation teams if routine testing becomes available in the future.

  18. Microplate alamarBlue Assay for Paracoccidioides Susceptibility Testing

    PubMed Central

    de Paula e Silva, A. C. A.; Oliveira, H. C.; Silva, J. F.; Sangalli-Leite, F.; Scorzoni, L.; Fusco-Almeida, A. M.

    2013-01-01

    CLSI method M27-A3 is not available for use with dimorphic fungi, such as those of the Paracoccidioides genus. In this study, we developed a microdilution method and added the alamarBlue reagent to test the responses of Paracoccidioides brasiliensis and Paracoccidioides lutzii against amphotericin B and itraconazole antifungals. The test proved to be sensitive, practical, and inexpensive and can be used to monitor the activity of low-growth microorganisms and their response to various drugs. PMID:23345296

  19. Bacterial Cytological Profiling (BCP) as a Rapid and Accurate Antimicrobial Susceptibility Testing Method for Staphylococcus aureus

    PubMed Central

    Quach, D.T.; Sakoulas, G.; Nizet, V.; Pogliano, J.; Pogliano, K.

    2016-01-01

    Successful treatment of bacterial infections requires the timely administration of appropriate antimicrobial therapy. The failure to initiate the correct therapy in a timely fashion results in poor clinical outcomes, longer hospital stays, and higher medical costs. Current approaches to antibiotic susceptibility testing of cultured pathogens have key limitations ranging from long run times to dependence on prior knowledge of genetic mechanisms of resistance. We have developed a rapid antimicrobial susceptibility assay for Staphylococcus aureus based on bacterial cytological profiling (BCP), which uses quantitative fluorescence microscopy to measure antibiotic induced changes in cellular architecture. BCP discriminated between methicillin-susceptible (MSSA) and -resistant (MRSA) clinical isolates of S. aureus (n = 71) within 1–2 h with 100% accuracy. Similarly, BCP correctly distinguished daptomycin susceptible (DS) from daptomycin non-susceptible (DNS) S. aureus strains (n = 20) within 30 min. Among MRSA isolates, BCP further identified two classes of strains that differ in their susceptibility to specific combinations of beta-lactam antibiotics. BCP provides a rapid and flexible alternative to gene-based susceptibility testing methods for S. aureus, and should be readily adaptable to different antibiotics and bacterial species as new mechanisms of resistance or multidrug-resistant pathogens evolve and appear in mainstream clinical practice. PMID:26981574

  20. Disk prediffusion is a reliable method for testing colistin susceptibility in porcine E. coli strains.

    PubMed

    Boyen, F; Vangroenweghe, F; Butaye, P; De Graef, E; Castryck, F; Heylen, P; Vanrobaeys, M; Haesebrouck, F

    2010-08-26

    During the last few years, acquired resistance to colistin in Escherichia coli, but also in other bacterial species, has been reported. It has been shown that the disk diffusion test is not a reliable method for the detection of this resistance. Therefore, there is a need for a reliable and cheap test to determine colistin susceptibility of pathogenic E. coli strains. In the current research, the colistin susceptibility of E. coli isolated during the period 2005-2006 from pigs was determined. Results obtained with the Kirby Bauer disk diffusion test (Neosensitabs, Rosco), the disk prediffusion test (Neosensitabs, Rosco) and the E-test (AB Biodisk) were compared with the results of the reference agar dilution assay. The MIC values or inhibition zones showed a bimodal distribution for the results obtained by all test methods, except the disk diffusion assay, suggesting acquired resistance in 15 strains (9.6%). The E-test and disk prediffusion assay generated results within acceptable levels compared to the reference agar dilution assay. The categorical agreement with the results obtained by the agar dilution method were good to very good for all tests, except the disk diffusion assay. In conclusion, current results suggest that, in addition to the E-test, the disk prediffusion test is a reliable, alternative agar-based colistin susceptibility method for testing colistin susceptibility of E. coli isolates in diagnostic bacteriology.

  1. Pyrazinamide susceptibility testing: proposed new standard with the BACTECTM MGITTM 960 system.

    PubMed

    Piersimoni, C; Mustazzolu, A; Iacobino, A; Giannoni, F; Santoro, G; Gherardi, G; Del Giudice, A; Perna, R; Fattorini, L

    2016-12-01

    The susceptibility of 253 Mycobacterium tuberculosis complex isolates to pyrazinamide (PZA) was assessed using the BACTECTM MGITTM 960 (M960) system. Resistant strains underwent paired repeat testing using 1) a critical concentration of 200 g/ml (PZA-200), and 2) a reduced inoculum of 0.25 ml. They were also examined using the BACTEC 460 (B460) reference method and investigated for pncA mutations. On M960, 37 isolates were resistant. In the PZA-200 assay, 20 of these were resistant and 17 susceptible, while 18 were resistant and 19 susceptible with reduced inoculum. The B460 assay and pncA sequencing confirmed results with reduced inoculum.

  2. 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

  3. 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

  4. Utility of in-house fluconazole disk diffusion susceptibility testing in the treatment of candidemia.

    PubMed

    Kubiak, David W; Farmakiotis, Dimitrios; Arons, Viktoria; Hollins, Randy M; Rostas, Sara E; Weiser, Linda M; Baden, Lindsey R; Marty, Francisco M; Koo, Sophia

    2016-03-01

    Among 302 first candidemia episodes, 210 (69.6%) were initially treated with an echinocandin or polyene (E/P) antifungal drug. In 137 (72.5%) patients with fluconazole-susceptible isolates, treatment was changed to fluconazole based on disk diffusion susceptibility testing. Clinical outcomes were not compromised in patients receiving E/P who were de-escalated to fluconazole for treatment of candidemia based on disk diffusion results.

  5. Utility of in-house fluconazole disk diffusion susceptibility testing in the treatment of candidemia

    PubMed Central

    Kubiak, David W.; Farmakiotis, Dimitrios; Arons, Viktoria; Hollins, Randy M.; Rostas, Sara E.; Weiser, Linda M.; Baden, Lindsey R.; Marty, Francisco M.; Koo, Sophia

    2016-01-01

    Among 302 first candidemia episodes, 210 (69.6%) were initially treated with an echinocandin or polyene (E/P) antifungal drug. In 137 (72.5%) patients with fluconazole-susceptible isolates, treatment was changed to fluconazole based on disk diffusion susceptibility testing. Clinical outcomes were not compromised in patients receiving E/P who were de-escalated to fluconazole for treatment of candidemia based on disk diffusion results. PMID:26763713

  6. Screening for cephalosporin-resistant Streptococcus pneumoniae with the Kirby-Bauer disk susceptibility test.

    PubMed

    Friedland, I R; Shelton, S; McCracken, G H

    1993-06-01

    Kirby-Bauer disk susceptibility tests with five standard cephalosporin disks were performed on 23 penicillin-resistant Streptococcus pneumoniae isolates for which ceftriaxone MICs were 0.125 to 4 micrograms/ml. Cefuroxime disk inhibition zone diameters distinguished clearly isolates for which ceftriaxone MICs were > or = 2 micrograms/ml from more susceptible strains, whereas cephalothin, ceftizoxime, cefotaxime, and ceftriaxone disks distinguished these isolates less clearly than the cefuroxime disk did.

  7. What's New in Genetic Testing for Cancer Susceptibility?

    PubMed

    Plichta, Jennifer K; Griffin, Molly; Thakuria, Joseph; Hughes, Kevin S

    2016-09-15

    The advent of next-generation sequencing, and its transition further into the clinic with the US Food and Drug Administration approval of a cystic fibrosis assay in 2013, have increased the speed and reduced the cost of DNA sequencing. Coupled with a historic ruling by the Supreme Court of the United States that human genes are not patentable, these events have caused a seismic shift in genetic testing in clinical medicine. More labs are offering genetic testing services; more multigene panels are available for gene testing; more genes and gene mutations are being identified; and more variants of uncertain significance, which may or may not be clinically actionable, have been found. All these factors, taken together, are increasing the complexity of clinical management. While these developments have led to a greater interest in genetic testing, risk assessment, and large-scale population screening, they also present unique challenges. The dilemma for clinicians is how best to understand and manage this rapidly growing body of information to improve patient care. With millions of genetic variants of potential clinical significance and thousands of genes associated with rare but well-established genetic conditions, the complexities of genetic data management clearly will require improved computerized clinical decision support tools, as opposed to continued reliance on traditional rote, memory-based medicine.

  8. A Simplified Test for Blanching Susceptibility of Copper Alloys

    NASA Technical Reports Server (NTRS)

    Thomas-Ogbuji, Linus U.; Humphrey, Donald; Setlock, John

    2003-01-01

    GRCop-84 (Cu-8Cr-4Nb) is a dispersion-strengthened alloy developed for space-launch rocket engine applications, as a liner for the combustion chamber and nozzle ramp. Its main advantage over rival alloys, particularly NARloy-Z (Cu-Ag-Zr), the current liner alloy, is in high temperature mechanical properties. Further validation required that the two alloys be compared with respect to service performance and durability. This has been done, under conditions resembling those expected in reusable launch engine applications. GRCop-84 was found to have a superior resistance to static and cyclic oxidation up to approx. 700 C. In order to improve its performance above 700 C, Cu-Cr coatings have also been developed and evaluated. The major oxidative issue with Cu alloys is blanching, a mode of degradation induced by oxidation-reduction fluctuations in hydrogen-fueled engines. That fluctuation cannot be addressed with conventional static or cyclic oxidation testing. Hence, a further evaluation of the alloy substrates and Cu-Cr coating material necessitated our devising a test protocol that involves oxidaton-reduction cycles. This paper describes the test protocols used and the results obtained.

  9. A Meta-Analytic Investigation of the Susceptibility of Integrity Tests to Faking and Coaching.

    ERIC Educational Resources Information Center

    Alliger, George M.; Dwight, Stephen A.

    2000-01-01

    Performed a meta-analysis of studies of the extent to which individuals can inflate their integrity test scores when coached or instructed to fake good. Results from 14 studies indicate that overt tests are more susceptible to both fake-good and coaching instructions than are personality-based measures. (SLD)

  10. Guidance for clinical and public health laboratories testing for influenza virus antiviral drug susceptibility in Europe.

    PubMed

    Pozo, Francisco; Lina, Bruno; Andrade, Helena Rebelo de; Enouf, Vincent; Kossyvakis, Athanasios; Broberg, Eeva; Daniels, Rod; Lackenby, Angie; Meijer, Adam

    2013-05-01

    Two classes of antiviral drugs are licensed in Europe for treatment and prophylaxis of influenza; the M2 ion-channel blockers amantadine and rimantadine acting against type A influenza viruses only and the neuraminidase enzyme inhibitors zanamivir and oseltamivir acting against type A and type B influenza viruses. This guidance document was developed for but not limited to the European Union (EU) and other European Economic Area (EEA) countries on how and when to test for influenza virus antiviral drug susceptibility. It is aimed at clinical and influenza surveillance laboratories carrying out antiviral drug susceptibility testing on influenza viruses from patients suspected of harbouring viruses with reduced susceptibility or for the monitoring of the emergence of such among circulating viruses, respectively. Therefore, the guidance should not be read as a directive or an algorithm for treatment. Monitoring for emergence of influenza viruses with reduced drug susceptibility in hospitalized cases is crucial for decision making on possible changes to antiviral treatment. Therefore, it is important to test for antiviral susceptibility in certain patient groups, such as patients treated with influenza antiviral drugs. It is also important to determine the frequency of viruses with natural (not related to drug use) reduced susceptibility among community and hospitalized cases, as this knowledge is essential for making empirical antiviral treatment decisions. Furthermore, testing of specimens from community influenza patients is needed to determine the frequency of viruses with reduced susceptibility and good viral fitness that are readily transmissible, as they may become dominant among circulating viruses. Phenotypic neuraminidase enzyme inhibition assays are recommended to determine the level of inhibition of the neuraminidase enzyme by antiviral drugs as a measure of drug susceptibility of the virus. Genotypic assays are recommended to identify amino acid

  11. Comparison and Development of Pyrazinamide Susceptibility Testing Methods for Tuberculosis in Thailand

    PubMed Central

    Foongladda, Suporn; Klayut, Wiphat; Pholwat, Suporn; Houpt, Eric

    2015-01-01

    Pyrazinamide (PZA) plays a critical role in shortening tuberculosis treatment duration and in treating MDR-TB. The standard phenotypic MGIT PZA susceptibility testing method is imperfect because it is slow and has potential for false resistance. In this study we evaluated two different phenotypic based methods, qPCR phage assay and MTT assay, as well as genotypic sequencing. The assay was evaluated on 71 clinical M. tuberculosis isolates (37 MGIT PZA susceptible, 34 MGIT PZA resistant) and compared to the MGIT result. Of these methods the qPCR phage assay yielded an accuracy of 89% versus standard MGIT while MTT yielded 83%. The genotypic sequencing method yielded 90% accuracy. We conclude that any of these faster PZA susceptibility methods perform reasonably well against a MGIT PZA susceptibility standard. PMID:26298819

  12. A two-hour antibiotic susceptibility test by ATP-bioluminescence.

    PubMed

    March Rosselló, Gabriel Alberto; García-Loygorri Jordán de Urries, María Cristina; Gutiérrez Rodríguez, María Purificación; Simarro Grande, María; Orduña Domingo, Antonio; Bratos Pérez, Miguel Ángel

    2016-01-01

    The antibiotic susceptibility test (AST) in Clinical Microbiology laboratories is still time-consuming, and most procedures take 24h to yield results. In this study, a rapid antimicrobial susceptibility test using ATP-bioluminescence has been developed. The design of method was performed using five ATCC collection strains of known susceptibility. This procedure was then validated against standard commercial methods on 10 strains of enterococci, 10 staphylococci, 10 non-fermenting gram negative bacilli, and 13 Enterobacteriaceae from patients. The agreement obtained in the sensitivity between the ATP-bioluminescence method and commercial methods (E-test, MicroScan and VITEK2) was 100%. In summary, the preliminary results obtained in this work show that the ATP-bioluminescence method could provide a fast and reliable AST in two hours.

  13. Recovery and susceptibility testing of Mycobacterium tuberculosis from extrapulmonary specimens by the BACTEC radiometric method.

    PubMed Central

    Fadda, G; Roe, S L

    1984-01-01

    This study was carried out to evaluate the sensitivity and rapidity of the BACTEC radiometric techniques for isolation and susceptibility testing of mycobacteria from extrapulmonary specimens. Concentrated specimens of urine, pleural fluid, and blood as well as other extrapulmonary specimens were processed for the recovery of mycobacteria and for drug susceptibility testing, employing conventional and BACTEC radiometric methods. Out of 483 specimens processed, 20 were found to be positive for Mycobacterium tuberculosis on the conventional Lowenstein -Jensen medium, and 19 were found to be positive in the BACTEC 7H12 medium. Average recovery times were 22.5 days for the conventional method and 10.9 days for the BACTEC method. When isolated cultures were tested for susceptibility to streptomycin, isoniazid, rifampin, and ethambutol, results were reported at an average time of 22 and 5.4 days for the conventional and BACTEC methods, respectively, with good correlation. PMID:6429193

  14. Evaluation of a radiometric method for pyrazinamide susceptibility testing of Mycobacterium tuberculosis.

    PubMed Central

    Tarrand, J J; Spicer, A D; Gröschel, D H

    1986-01-01

    Pyrazinamide susceptibility testing of Mycobacterium tuberculosis requires an acid environment. By controlling the method of acidification and the quality and quantity of the inoculum, the test can be performed with the BACTEC radiometric system (Johnston Laboratories, Towson, Md.). We acidified BACTEC 7H12 medium with buffered phosphoric acid and adjusted the test inoculum to 1/10 of that usually employed in BACTEC protocols; after 5 days of growth we correctly identified 36 of 36 strains susceptible to 50 micrograms of pyrazinamide per ml. All 18 resistant strains were classified as pyrazinamide resistant. (Susceptibility or resistance had been determined by standard plate assays.) The test was able to detect small resistant populations in artificial mixtures of 1 or 2% resistant bacteria with a susceptible strain (10 mixtures each). We tested 70 M. tuberculosis strains in acidified BACTEC 7H12 medium and by the plate dilution test at pH 5.5. All strains grew in the BACTEC medium, but three strains failed to grow on plates and were not tested further; the results of both methods agreed for the remaining strains. PMID:3101586

  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. Plaque inhibition assay for drug susceptibility testing of influenza viruses.

    PubMed Central

    Hayden, F G; Cote, K M; Douglas, R G

    1980-01-01

    The relative antiviral activities of four drugs against contemporary strains of influenza A and B viruses were determined in Madin-Darby canine kidney cell monolayers with a plaque inhibition assay. This assay proved to be a reliable, rapid method of determining 50% inhibitory concentrations that correlated well with clinically achievable drug levels and the results of clinical trials. Contemporary strains of influenza A viruses (subtypes H1N1, H3N2, HSW1N1) required amantadine hydrochloride and rimantadine hydrochloride 50% inhibitory concentrations in the range of 0.2 to 0.4 microgram/ml, whereas 50% inhibitory concentrations ranged from approximately 50 to 100 micrograms/ml against influenza B viruses. Ribavirin was approximately 10-fold less active than amantadine hydrochloride against influenza A viruses, and the ribavirin 50% inhibitory concentrations against both influenza A and B viruses ranged from 2.6 to 6.8 micrograms/ml. Inosiplex had no antiviral activity in this test system. PMID:7396473

  17. Standardization of disk diffusion test and its clinical significance for susceptibility testing of metronidazole against Helicobacter pylori.

    PubMed Central

    Xia, H; Keane, C T; Beattie, S; O'Morain, C A

    1994-01-01

    Susceptibilities of 121 clinical Helicobacter pylori strains to metronidazole were determined by both a 5-micrograms metronidazole disk diffusion test and a plate dilution method in duplicate and after different periods of incubation. The distribution of MICs of metronidazole against H. pylori among the strains was found to be bimodal. The diameters of inhibitory zones obtained by the disk diffusion test and the MICs obtained by the plate dilution method correlated well, especially after 4 days of incubation (r = 0.77). An inhibitory zone diameter of 20 mm was found to correspond to a MIC of 8 micrograms/ml and is recommended as a suitable zone for differentiating susceptibility and resistance with a 5-micrograms metronidazole disk. Three interpretive categories of susceptibility results were defined; strains with inhibitory zone diameters of more than 26 mm were defined as susceptible (MIC, < 4 micrograms/ml), strains with zone diameters of 20 to 26 mm were deemed intermediate (MIC, 4 to 8 micrograms/ml), and those with zone diameters of less than 20 mm were deemed resistant (MIC, > 8 micrograms/ml). Furthermore, 76 H. pylori-positive patients with duodenal ulcers or nonulcer dyspepsia were treated with a 1 week of triple therapy (colloidal bismuth subcitrate, metronidazole, and tetracycline). H. pylori strains were isolated before treatment from antral biopsies from those patients, and the metronidazole susceptibilities of the strains were determined by the disk diffusion test. H. pylori status was evaluated again 4 weeks after completion of treatment. The eradication rates for susceptible, intermediate, and resistant strains were 95.9% (47 of 49), 62.5% (5 of 8), and 52.6% (10 of 19), respectively. It is included that the 5-micrograms disk diffusion test is easy to perform and gives final results similar to those of the plate dilution method. The three interpretive categories of susceptibility may be of benefit for clinical choice of chemotherapy in eradicating

  18. Conditions that may affect the results of susceptibility testing of Mycobacterium tuberculosis to pyrazinamide.

    PubMed

    Zhang, Ying; Permar, Sallie; Sun, Zhonghe

    2002-01-01

    Pyrazinamide (PZA) is an important front-line anti-tuberculosis drug that is active only at acid pH. However, acid pH causes significant difficulty for PZA susceptibility testing. A common problem in PZA testing is false resistance caused by large bacterial inocula. This study investigated the relationship of false resistance to numbers of bacilli, pH and other factors that potentially affect susceptibility to PZA. Large inocula (10(7-8) bacilli/ml) of M. tuberculosis H37Ra caused significant increase in medium pH from 5.5 towards neutrality, and thus produced false resistance results. The increase in medium pH was determined to be a function of live bacilli; heat-killed bacilli had little or no effect. Susceptibility to PZA and its active derivative pyrazinoic acid (POA) was comparable on 7H11 agar medium, but POA was less active than PZA in liquid medium containing bovine serum albumin (BSA), suggesting that susceptibility to PZA or POA was reduced in the presence of BSA, because of its neutralising effect on medium pH and significant POA binding. A 3-month-old H37Ra culture was shown to be more susceptible to PZA exposure than a 4-day log-phase culture, suggesting that PZA is more active for non-growing bacilli. Finally, reserpine, an inhibitor of POA efflux pump, increased susceptibility to PZA even near neutral pH 6.8, with an MIC of 400 mg/L compared with 1,000 mg/L without reserpine. These findings should have implications for understanding the mode of action of PZA and for PZA susceptibility testing.

  19. Antibiotic Susceptibility Testing of the Gram-Negative Bacteria Based on Flow Cytometry

    PubMed Central

    Saint-Ruf, Claude; Crussard, Steve; Franceschi, Christine; Orenga, Sylvain; Ouattara, Jasmine; Ramjeet, Mahendrasingh; Surre, Jérémy; Matic, Ivan

    2016-01-01

    Rapidly treating infections with adequate antibiotics is of major importance. This requires a fast and accurate determination of the antibiotic susceptibility of bacterial pathogens. The most frequently used methods are slow because they are based on the measurement of growth inhibition. Faster methods, such as PCR-based detection of determinants of antibiotic resistance, do not always provide relevant information on susceptibility, particularly that which is not genetically based. Consequently, new methods, such as the detection of changes in bacterial physiology caused by antibiotics using flow cytometry and fluorescent viability markers, are being explored. In this study, we assessed whether Alexa Fluor® 633 Hydrazide (AFH), which targets carbonyl groups, can be used for antibiotic susceptibility testing. Carbonylation of cellular macromolecules, which increases in antibiotic-treated cells, is a particularly appropriate to assess for this purpose because it is irreversible. We tested the susceptibility of clinical isolates of Gram-negative bacteria, Escherichia coli and Pseudomonas aeruginosa, to antibiotics from the three classes: β-lactams, aminoglycosides, and fluoroquinolones. In addition to AFH, we used TO-PRO®-3, which enters cells with damaged membranes and binds to DNA, and DiBAC4 (3), which enters cells with depolarized membranes. We also monitored antibiotic-induced morphological alterations of bacterial cells by analyzing light scattering signals. Although all tested dyes and light scattering signals allowed for the detection of antibiotic-sensitive cells, AFH proved to be the most suitable for the fast and reliable detection of antibiotic susceptibility. PMID:27507962

  20. Rapid screening tests for determining in vitro susceptibility of herpes simplex virus clinical isolates.

    PubMed

    de la Iglesia, P; Melón, S; López, B; Rodriguez, M; Blanco, M I; Mellado, P; de Oña, M

    1998-08-01

    The susceptibility of human herpes simplex virus (HSV) to acyclovir (ACV) was determined with the use of a single dose of the drug (1 and 2 micrograms of ACV per ml for HSV-1 and HSV-2, respectively) in two rapid assays: a rapid cytopathic effect inhibitory assay (Rapid CIA) and a rapid dye uptake assay (Rapid DUA). These tests allow the simultaneous determination of virus titer and susceptibility to ACV at a determined viral concentration (100 50% tissue culture infective doses and 100 50% dye uptake units). These tests were compared with a conventional susceptibility assay (dye uptake assay) and showed similar results. Indeterminate results with the Rapid CIA appeared in 3 of 30 samples. With the use of both Rapid CIA and Rapid DUA, we were able to determine the susceptibility of 100% of the isolates. The rapid tests, unlike conventional assays, are able to provide susceptibility results within 3 days after the virus has been isolated from a clinical specimen and could thus play a direct role in therapeutic decisions.

  1. EUCAST recommendations for antimicrobial susceptibility testing applied to the three main Campylobacter species isolated in humans.

    PubMed

    Sifré, Elodie; Salha, Ben Amor; Ducournau, Astrid; Floch, Pauline; Chardon, Hubert; Mégraud, Francis; Lehours, Philippe

    2015-12-01

    Antimicrobial susceptibility testing of Campylobacter isolates is of great importance for treatment options especially in systemic diseases. The European Committee for Antimicrobial Susceptibility Testing (EUCAST) recently proposed epidemiological cut-offs (ECOFFs) for a limited number of antimicrobial compounds and for Campylobacter jejuni and Campylobacter coli only. In the present study, the EUCAST method was used after minor modifications to define antimicrobial susceptibility patterns for, 1997 C. jejuni, 419 C. coli and 100 Campylobacter fetus strains received at the French National Reference Center for Campylobacters and Helicobacters. Our results show that the ECOFFs defined by EUCAST for tetracycline and ciprofloxacin can be used for C. jejuni and C. coli. The same ECOFF can be used for erythromycin for the three species. The C. jejuni and C. coli ECOFFs for ciprofloxacin however cannot be applied to C. fetus. We also provide data to categorise two 2 β-lactams of interest for systemic diseases, ampicillin and amoxicillin+clavulanate, for the three species.

  2. Serogenotyping and antimicrobial susceptibility testing of Salmonella spp. isolated from retail meat samples in Lagos, Nigeria.

    PubMed

    Smith, Stella; Braun, Sascha; Akintimehin, Faith; Fesobi, Toun; Bamidele, Moses; Coker, Akitoye; Monecke, Stefan; Ehricht, Ralf

    2016-08-01

    Microarray-based serogenotyping, antimicrobial susceptibility tests and the detection of relevant resistance genes were performed on isolates of Salmonella spp. from retail meat samples obtained in Lagos, Nigeria. Out of 151 meat samples, 33 Salmonella isolates were obtained. Nine different Salmonella serovars (S. Amoutive, S. Bargny, S. Drac, S. Ealing, S. Urbana, S. Hadar, S. Nyborg, S. Anatum and S. Havana) were identified by microarray-based serogenotyping and confirmed afterwards using classical serotyping. Antibiotic susceptibility tests with 17 antibiotics showed that almost all isolates were fully susceptible to this panel. The results of this study indicated a high prevalence of Salmonella in retail meat, the presence of some previously rather rarely described Serovars in retail meat samples from Lagos, and a need to monitor for Salmonella and their antibiotic resistance determinants. The microarray-based system used herein proved to be perfectly suited as epidemiological tool to replace classical serotyping.

  3. Antimicrobial susceptibility testing of bovine digital dermatitis treponemes identifies macrolides for in vivo efficacy testing.

    PubMed

    Evans, N J; Brown, J M; Hartley, C; Smith, R F; Carter, S D

    2012-12-07

    Digital dermatitis (DD) is a major infectious lameness of dairy cattle and sheep considered to be caused by treponemes. The aim of this study was to identify antibiotics effective against DD treponemes that might be useful in the treatment of ruminant DD in the future or to identify antibiotics useful in isolation studies. Here, a microdilution method was used to identify in vitro antimicrobial susceptibility of treponemes cultured from DD lesions to eight relevant antibiotics. DD treponemes exhibited highest susceptibility to amoxicillin, azithromycin and gamithromycin. Unfortunately, amoxicillin whilst having potential for DD treatment in other animals (e.g. sheep) would require milk withhold periods in dairy cattle. DD treponemes were not particularly susceptible to two cephalosporins: cefalexin and ceftiofur, which do not require milk withhold. The bacteria demonstrated low susceptibility to trimethoprim and especially colistin suggesting these antimicrobials may be particularly useful in isolation of DD treponemes. The most promising high susceptibility results for macrolides indicate a rationale to consider veterinary licensed macrolides as DD treatments. Furthermore, given the DD treponeme antibiotic susceptibility similarities to established treatments for human treponematoses, identification of treponemacidal, long acting β-lactam analogues not requiring milk withhold may allow for development of a successful treatment for dairy cattle DD.

  4. Recommendation for a Standardised Method of Broth Microdilution Susceptibility Testing for Porcine Bordetella bronchiseptica

    PubMed Central

    Prüller, Sandra; Frömke, Cornelia; Kaspar, Heike; Klein, Günter; Kreienbrock, Lothar; Kehrenberg, Corinna

    2015-01-01

    The objective was to establish and standardise a broth microdilution susceptibility testing method for porcine Bordetella (B.) bronchiseptica. B. bronchiseptica isolates from different geographical regions and farms were genotyped by macrorestriction analysis and subsequent pulsed-field gel electrophoresis. One reference and one type strain plus two field isolates of B. bronchiseptica were chosen to analyse growth curves in four different media: cation-adjusted Mueller-Hinton broth (CAMHB) with and without 2% lysed horse blood, Brain-Heart-Infusion (BHI), and Caso broth. The growth rate of each test strain in each medium was determined by culture enumeration and the suitability of CAMHB was confirmed by comparative statistical analysis. Thereafter, reference and type strain and eight epidemiologically unrelated field isolates of B. bronchiseptica were used to test the suitability of a broth microdilution susceptibility testing method following CLSI-approved performance standards given in document VET01-A4. Susceptibility tests, using 20 antimicrobial agents, were performed in five replicates, and data were collected after 20 and 24 hours incubation and statistically analysed. Due to the low growth rate of B. bronchiseptica, an incubation time of 24 hours resulted in significantly more homogeneous minimum inhibitory concentrations after five replications compared to a 20-hour incubation. An interlaboratory comparison trial including susceptibility testing of 24 antimicrobial agents revealed a high mean level of reproducibility (97.9%) of the modified method. Hence, in a harmonization for broth microdilution susceptibility testing of B. bronchiseptica, an incubation time of 24 hours in CAMHB medium with an incubation temperature of 35°C and an inoculum concentration of approximately 5 x 105 cfu/ml was proposed. PMID:25910232

  5. Rapid, modified Kirby-Bauer susceptibility test with single, high-concentration antimicrobial disks.

    PubMed

    Boyle, V J; Fancher, M E; Ross, R W

    1973-03-01

    A rapid (6-7 hr), modified Kirby-Bauer disk-susceptibility method, by which derivatives of tetrazolium dyes are used to enhance delineation between areas of growth and zones of inhibition, has been developed. Inoculated petri plates, prepared by the Kirby-Bauer method, were sprayed, after 6 to 7 hr of incubation (37 C), with aqueous solutions of MTT-tetrazolium or INT-tetrazolium resulting in readily detectable zones of inhibition. Excellent correlation was obtained between the modified test and the standard Kirby-Bauer test when challenged with a variety of gram-negative bacteria and Staphylococcus aureus strains. Additionally, the modified test has demonstrated reproducibility comparable to the standard Kirby-Bauer test. It is demonstrated that the modified test is applicable to susceptibility determinations with representative, commercially available antimicrobial disks. This applicability indicates that the modified method could provide rapid in vitro guidelines for in vivo therapy.

  6. Comparative study of agar diffusion test and the NCCLS macrobroth method for in vitro susceptibility testing of Candida spp.

    PubMed

    Soni, L M; Burattini, M N; Pignatari, A C; Gompertz, O F; Colombo, A L

    1999-01-01

    We performed a prospective double-blind study to evaluate the correlation between inhibition zones obtained by a disk-diffusion test, using Neo-sensitabs of fluconazole (Rosco Diagnostica), and the MICs generated by the NCCLS macrobroth dilution assay. Eighty clinical isolates, representing 5 of the clinically relevant species of Candida, were tested simultaneously by both methods. A clear inverse correlation was found between the results obtained by both tests (r = -0.69). In addition, there was high degree of agreement between methods in the identification of susceptible isolates. However, the resistance definition by disk-diffusion test had a positive predictive value of only 17%. Our data support the hypothesis that Rosco Fluconazole Neo-sensitabs have potential as a screening test for the identification of Candida isolates susceptible to fluconazole. Resistant isolates should be further investigated by standardized broth procedures.

  7. Dobutamine "stress" test and latent cardiac susceptibility to inhaled diesel exhaust in normal and hypertensive rats**

    EPA Science Inventory

    Background -Exercise "stress" testing is a screening tool used to determine the amount of stress for which the heart can compensate before developing abnormal rhythm or ischemia, particularly in susceptible people. Although this approach has been used to assess risk in humans exp...

  8. Antimicrobials, susceptibility testing, and minimum inhibitory concentrations (MIC) in veterinary infection treatment.

    PubMed

    Papich, Mark G

    2013-09-01

    Veterinarians are quick to attribute an unsuccessful antimicrobial treatment to a failure of the culture and susceptibility test. There are many reasons why antimicrobial treatment fails. When evaluating a patient that has failed to respond to therapy, one must consider any of the many factors that contribute to antibiotic failure.

  9. Contemporary tetracycline susceptibility testing: doxycycline MIC methods and interpretive criteria (CLSI and EUCAST) performance when testing Gram-positive pathogens.

    PubMed

    Jones, Ronald N; Stilwell, Matthew G; Wilson, Michael L; Mendes, Rodrigo E

    2013-05-01

    International susceptibility testing breakpoint organizations and regulatory agencies have markedly differing interpretive criteria for the tetracycline class. Here we examined the magnitude of these differences for doxycycline and tetracycline hydrochloride (HCL) when tested against a collection of 13,176 Gram-positive cocci from a worldwide surveillance network (SENTRY Antimicrobial Surveillance Program, 2010). Clinical and Laboratory Standards Institute (CLSI) breakpoints are routinely higher, usually 4-fold, compared to those of the European Committee on Antimicrobial Susceptibility Testing (EUCAST); however, CLSI recently (2013) modified Streptococcus pneumoniae breakpoints (≤ 2 μg/mL in 2012) to ≤ 0.25 and ≤ 1 μg/mL for doxycycline and tetracycline HCL, respectively. We report that these changes are a promising step toward international breakpoint harmonization, but lack a comprehensive approach needed for testing tetracyclines against all Gram-positive cocci. Generally, EUCAST breakpoint criteria showed i) lower spectrums (reduced susceptibility rates) for the tetracyclines, but highest for doxycycline versus all species examined; ii) greater test accuracy (lower predictive categorical errors), especially for tetracycline to predict doxycycline susceptibility (99.91%); and iii) zone diameter correlate breakpoints which are generally available online. Molecular tests for tet resistance genes demonstrate that tet (K) and tet (M) containing strains can occur in the susceptible population of MIC results by both CLSI and EUCAST breakpoint criteria. In summary, doxycycline continues to show greater comparative potency versus tetracycline HCL against all monitored Gram-positive species and the international harmonization of tetracycline breakpoints should be a priority, as the most recent CLSI update only addressed 1 streptococcal species and 2 tetracycline agents.

  10. Multilaboratory Evaluation of In Vitro Antifungal Susceptibility Testing of Dermatophytes for ME1111

    PubMed Central

    Chaturvedi, V.; Diekema, D.; Ostrosky-Zeichner, L.; Rennie, R.; Walsh, T.; Wengenack, N.; Fothergill, A.; Wiederhold, N.

    2015-01-01

    ME1111 is a novel small molecule antifungal agent under development for the topical treatment of onychomycosis. Standardization of the susceptibility testing method for this candidate antifungal is needed. Toward this end, 8 independent laboratories determined the interlaboratory reproducibility of ME1111 susceptibility testing. In addition, we subsequently identified 2 strains as quality control (QC) isolates for the method. In the reproducibility study, 5 blinded clinical strains each of Trichophyton rubrum, Trichophyton mentagrophytes, and Epidermophyton floccosum were tested, while the QC study tested 6 blinded T. rubrum or T. mentagrophytes ATCC strains. Testing was performed in frozen microtiter panels according to the Clinical and Laboratory Standards Institute (CLSI) M38-A2 methodology. In the reproducibility study, 9 of 15 clinical strains showed interlaboratory agreement of >90% at the 80% inhibition endpoint, with a range of agreement of 76.2% to 100%. In the QC study, 4 of the 6 ATCC strains showed interlaboratory agreement of >90%. ME1111 demonstrated excellent interlaboratory agreement when tested against dermatophytes. Based on this data, the CLSI Subcommittee on Antifungal Susceptibility Tests approved the susceptibility testing of ME1111 against dermatophytes according to M38-A2 methodology, which stipulates RPMI 1640 as the test medium, an inoculum size of 1 to 3 × 103 CFU/ml, and an incubation time and temperature of 96 h at 35°C. The MIC endpoint should be 80% inhibition compared with the growth control. T. rubrum ATCC MYA-4438 and T. mentagrophytes ATCC 28185 were selected as QC isolates, with an acceptable range of 0.12 to 1 μg/ml for the two strains. PMID:26719434

  11. Computerised emission and susceptibility MIL.STD testing with automated NB/BB detection

    NASA Astrophysics Data System (ADS)

    Vanessen, J. C.

    1990-09-01

    Automation of Electromagnetic Compatibility (EMC) testing is becoming common at many EMC test facilities. Commercial automated systems have become available in the past few years. The test and operations section has developed its own EMC automation to enhance and aid in testing. A complete overview of the automated EMC test facility in operation for emission and susceptibility measurements is presented. It includes a hardware description, the program structure and some of the methods required to complete such a program on the equipment chosen, including the Narrow Band (NB) and Broad Band (BB).

  12. Diagnosis of coccidioidomycosis by culture: safety considerations, traditional methods, and susceptibility testing.

    PubMed

    Sutton, Deanna A

    2007-09-01

    The recovery of Coccidioides spp. by culture and confirmation utilizing the AccuProbe nucleic acid hybridization method by GenProbe remain the definitive diagnostic method. Biosafety considerations from specimen collection through culture confirmation in the mycology laboratory are critical, as acquisition of coccidioidomycosis by laboratory workers is well documented. The designation of Coccidioides spp. as select agents of potential bioterrorism has mandated strict regulation of their transport and inventory. The genus appears generally susceptible, in vitro, although no defined breakpoints exist. Susceptibility testing may assist in documenting treatment failures.

  13. Antimicrobial Susceptibility Testing, Drug Resistance Mechanisms, and Therapy of Infections with Nontuberculous Mycobacteria

    PubMed Central

    Nash, Kevin A.; Wallace, Richard J.

    2012-01-01

    Summary: Within the past 10 years, treatment and diagnostic guidelines for nontuberculous mycobacteria have been recommended by the American Thoracic Society (ATS) and the Infectious Diseases Society of America (IDSA). Moreover, the Clinical and Laboratory Standards Institute (CLSI) has published and recently (in 2011) updated recommendations including suggested antimicrobial and susceptibility breakpoints. The CLSI has also recommended the broth microdilution method as the gold standard for laboratories performing antimicrobial susceptibility testing of nontuberculous mycobacteria. This article reviews the laboratory, diagnostic, and treatment guidelines together with established and probable drug resistance mechanisms of the nontuberculous mycobacteria. PMID:22763637

  14. [Performance evaluation of VITEK 2 system in meropenem susceptibility testing of clinical Pseudomonas aeruginosa isolates].

    PubMed

    Acuner, Ibrahim Cağatay; Bayramoğlu, Gülçin; Birinci, Asuman; Cekiç Cihan, Ciğdem; Bek, Yüksel; Durupınar, Belma

    2011-07-01

    Pseudomonas aeruginosa is an important opportunistic pathogen associated with various community-acquired or nosocomial infections. Multi-drug resistant P.aeruginosa strains increasingly cause epidemics and spread in various hospital wards and geographic regions. Carbapenems are among the most effective antimicrobials in the treatment of multi-drug resistant P.aeruginosa infections, and meropenem is the most successful among alternatives in initial therapy. Particularly in severe infections, inappropriate or inadequate initial antimicrobial therapy is independently associated with adverse clinical and economic outcomes. Availability of accurate and rapid susceptibility testing is a priority. Most of the automated microbiology systems can provide rapid results within 8 to 12 hours. In comparison to standard methods, problems in the antimicrobial susceptibility testing of particular microorganisms and antimicrobial agents have been reported for automated microbiology systems. Failures have been reported previously especially in the susceptibility testing of P.aeruginosa versus carbapenem. Most of these studies are designed according to the Food and Drug Administration (FDA, USA) performance analysis scheme (Class II Special Controls Guidance Document: Antimicrobial Susceptibility Test Systems) in a simplified form. However, there are many lacking issues in the design of most of these studies. Among these, insufficient sample size, use of inappropriate reference method, lack of reproducibility testing, and inadequate distribution of study isolates in interpretative categories are of notice. There are only few studies in the literature that evaluate the performance of automated systems in antimicrobial susceptibility testing of carbapenems in clinical P.aeruginosa isolates with a sufficient sample size (n ? 100). However, most of these studies still have one or more major deficiencies in the study design. Furthermore, none of these studies evaluate the performance of

  15. Auditory Tests for the Early Detection of Noise-Susceptible Individuals - A Literature Study

    DTIC Science & Technology

    2005-04-01

    continues to be a high incidence of noise-induced hearing loss ( NIHL ) among military personnel. One of the ways to reduce the adverse effects of...to NIHL . In the literature various auditory tests are proposed that measure items such as loudness discrimination, octave masking, frequency...of the individual susceptibility to NIHL can only be determined in longitudinal studies. In such studies, the promising auditory tests have to be

  16. Rapid bacterial antibiotic susceptibility test based on simple surface-enhanced Raman spectroscopic biomarkers

    PubMed Central

    Liu, Chia-Ying; Han, Yin-Yi; Shih, Po-Han; Lian, Wei-Nan; Wang, Huai-Hsien; Lin, Chi-Hung; Hsueh, Po-Ren; Wang, Juen-Kai; Wang, Yuh-Lin

    2016-01-01

    Rapid bacterial antibiotic susceptibility test (AST) and minimum inhibitory concentration (MIC) measurement are important to help reduce the widespread misuse of antibiotics and alleviate the growing drug-resistance problem. We discovered that, when a susceptible strain of Staphylococcus aureus or Escherichia coli is exposed to an antibiotic, the intensity of specific biomarkers in its surface-enhanced Raman scattering (SERS) spectra drops evidently in two hours. The discovery has been exploited for rapid AST and MIC determination of methicillin-susceptible S. aureus and wild-type E. coli as well as clinical isolates. The results obtained by this SERS-AST method were consistent with that by the standard incubation-based method, indicating its high potential to supplement or replace existing time-consuming methods and help mitigate the challenge of drug resistance in clinical microbiology. PMID:26997474

  17. A review of the current state of antimicrobial susceptibility test methods for Brachyspira.

    PubMed

    Kulathunga, Dharmasiri G R S; Rubin, Joseph E

    2017-03-21

    The re-emergence of swine dysentery (Brachyspira-associated muco-haemorrhagic colitis) since the late 2000's has illuminated diagnostic challenges associated with this genus. The methods used to detect, identify and characterize Brachyspira from clinical samples have not been standardized and laboratories frequently rely heavily on in-house techniques. Particularly concerning is the lack of standardized methods for determining and interpreting the antimicrobial susceptibility of Brachyspira spp. The integration of laboratory data into a treatment plan is a critical component of prudent antimicrobial usage, the lack of standardized methods is therefore an important limitation to the evidence based use of antimicrobials. This review will focus on describing the methodological limitations and inconsistencies between current susceptibility testing schemes employed for Brachyspira, provide an overview of what we do know about the susceptibility of these organisms and suggest future directions to improve and standardize diagnostic strategies.

  18. Rapid bacterial antibiotic susceptibility test based on simple surface-enhanced Raman spectroscopic biomarkers

    NASA Astrophysics Data System (ADS)

    Liu, Chia-Ying; Han, Yin-Yi; Shih, Po-Han; Lian, Wei-Nan; Wang, Huai-Hsien; Lin, Chi-Hung; Hsueh, Po-Ren; Wang, Juen-Kai; Wang, Yuh-Lin

    2016-03-01

    Rapid bacterial antibiotic susceptibility test (AST) and minimum inhibitory concentration (MIC) measurement are important to help reduce the widespread misuse of antibiotics and alleviate the growing drug-resistance problem. We discovered that, when a susceptible strain of Staphylococcus aureus or Escherichia coli is exposed to an antibiotic, the intensity of specific biomarkers in its surface-enhanced Raman scattering (SERS) spectra drops evidently in two hours. The discovery has been exploited for rapid AST and MIC determination of methicillin-susceptible S. aureus and wild-type E. coli as well as clinical isolates. The results obtained by this SERS-AST method were consistent with that by the standard incubation-based method, indicating its high potential to supplement or replace existing time-consuming methods and help mitigate the challenge of drug resistance in clinical microbiology.

  19. SUSCEPTIBILITY TEST FOR FUNGI: CLINICAL AND LABORATORIAL CORRELATIONS IN MEDICAL MYCOLOGY

    PubMed Central

    ALASTRUEY-IZQUIERDO, Ana; MELHEM, Marcia S.C.; BONFIETTI, Lucas X.; RODRIGUEZ-TUDELA, Juan L.

    2015-01-01

    SUMMARY During recent decades, antifungal susceptibility testing has become standardized and nowadays has the same role of the antibacterial susceptibility testing in microbiology laboratories. American and European standards have been developed, as well as equivalent commercial systems which are more appropriate for clinical laboratories. The detection of resistant strains by means of these systems has allowed the study and understanding of the molecular basis and the mechanisms of resistance of fungal species to antifungal agents. In addition, many studies on the correlation of in vitro results with the outcome of patients have been performed, reaching the conclusion that infections caused by resistant strains have worse outcome than those caused by susceptible fungal isolates. These studies have allowed the development of interpretative breakpoints for Candida spp. and Aspergillus spp., the most frequent agents of fungal infections in the world. In summary, antifungal susceptibility tests have become essential tools to guide the treatment of fungal diseases, to know the local and global disease epidemiology, and to identify resistance to antifungals. PMID:26465371

  20. Genetic Testing for the Susceptibility to Alcohol Dependence: Interest and Concerns in an African American Population

    PubMed Central

    Nwulia, Evaristus; Kwagyan, John; Cain, Gloria; Marshall, Vanessa J.; Kalu, Nnenna; Ewing, Altovise; Taylor, Robert E.

    2014-01-01

    Background: The search to identify genes for the susceptibility to alcohol dependence (AD) is generating interest for genetic risk assessment. The purpose of this study is to examine the level of interest and concerns for genetic testing for susceptibility to AD. Methods: Three hundred four African American adults were recruited through public advertisement. All participants were administered the Genetic Psycho-Social Implication (GPSI) questionnaire, which surveyed their interests in hypothetical genetic testing for AD, as well as their perception of ethical and legal concerns. Results: Over 85% of participants were interested in susceptibility genetic testing; however, persons with higher education (p=0.002) and income (p=0.008) were less willing to receive testing. Perception of AD as a deadly disease (48.60%) and wanting to know for their children (47.90%) were the strongest reasons for interest in testing. Among those not interested in testing, the belief that they were currently acting to lower their risk was the most prevalent. The most widely expressed concern in the entire sample was the accuracy of testing (35.50%). Other notable concerns, such as issues with the method of testing, side effects of venipuncture, falsely reassuring results, and lack of guidelines on “what to do next” following test results, were significantly associated with willingness to receive testing. Conclusion: Although an overwhelming majority of participants expressed an interest in genetic testing for AD, there is an understandable high level of methodological and ethical concerns. Such information should form the basis of policies to guide future genetic testing of AD. PMID:24926856

  1. 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

  2. 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.

  3. Canadian multicenter laboratory study for standardized second-line antimicrobial susceptibility testing of Mycobacterium tuberculosis.

    PubMed

    Sharma, Meenu; Thibert, Louise; Chedore, Pamela; Shandro, Cary; Jamieson, Frances; Tyrrell, Gregory; Christianson, Sara; Soualhine, Hafid; Wolfe, Joyce

    2011-12-01

    The purpose of this study was to establish a standardized protocol for second-line antimicrobial susceptibility testing of Mycobacterium tuberculosis using the Bactec MGIT 960 system in Canadian laboratories. Four Canadian public health laboratories compared the susceptibility testing results of 9 second-line antimicrobials between the Bactec 460 and Bactec MGIT 960 systems. Based on the data generated, we have established that the Bactec MGIT 960 system provides results comparable to those obtained with the previous Bactec 460 method. The critical concentrations established for the testing of the antimicrobials used are as follows: amikacin, 1 μg/ml; capreomycin, 2.5 μg/ml; ethionamide, 5 μg/ml; kanamycin, 2.5 μg/ml; linezolid, 1 μg/ml; moxifloxacin, 0.25 μg/ml; ofloxacin, 2 μg/ml; p-aminosalicylic acid, 4 μg/ml; rifabutin, 0.5 μg/ml.

  4. Direct antimicrobial drug susceptibility testing of Mycobacterium tuberculosis by the radiometric method

    SciTech Connect

    Libonati, J.P.; Stager, C.E.; Davis, J.R.; Siddiqi, S.H.

    1988-05-01

    Direct-drug-susceptibility tests were performed on clinical specimens positive for acid-fast bacilli by either Ziehl-Neelsen or fluorochrome staining. The results of conventional agar dilution and a modified radiometric (BACTEC) method were compared. A total of 580 smear-positive specimens were tested by the BACTEC method at three separate sites. Three hundred and seventy-seven of these were culture positive for M. tuberculosis, and 343 (91%) yielded acceptable direct-susceptibility-test results. We used the conventional method to determine that 343 of 519 smear-positive specimens were culture positive for M. tuberculosis, and 212 (62%) produced acceptable results within 3 wks. Conventional results were reported in 3-4 wks, while the time required to obtain results with the BACTEC method ranged from 5 to 21 days (average 11.5 days). Results indicate that the radiometric method provides reportable results more frequently with time savings as compared to the conventional method.

  5. Towards a Standardized Method for Broth Microdilution Susceptibility Testing of Haemophilus parasuis.

    PubMed

    Prüller, Sandra; Turni, Conny; Blackall, Patrick J; Beyerbach, Martin; Klein, Günter; Kreienbrock, Lothar; Strutzberg-Minder, Katrin; Kaspar, Heike; Meemken, Diana; Kehrenberg, Corinna

    2017-01-01

    Currently, there is no agreed method available for broth microdilution susceptibility testing of Haemophilus parasuis, one of the most important bacterial pathogens in pig production. Therefore, the aim of this study was to develop a method that could be easily performed by diagnostic laboratories and that appears suitable for a harmonized susceptibility testing. Growth determinations using one type strain and three field isolates revealed no visible growth of H. parasuis in media which have proven to be suitable for susceptibility testing of fastidious organisms. Therefore, a new medium, cation-adjusted Mueller-Hinton broth (CAMHB) plus NADH and sterile filtered heat-inactivated chicken serum, was developed. The reproducibility of MICs obtained in this medium was evaluated and statistically analyzed, considering a model with two different variables (precondition of five identical MICs and MIC mode accepting a deviation of ±1 dilution step, respectively). No significant differences for both variables were seen between two time points investigated and between results obtained with the recently proposed test medium broth (TMB). Nearly all MICs of quality control strains were in the acceptable range. Subsequently, 47 H. parasuis isolates representing 13 serovars were tested with the newly developed medium and TMB. Statistical analysis of all isolates and 15 antimicrobial agents and antimicrobial combinations showed no significant difference between MICs obtained in supplemented CAMHB and TMB. Because of a simplified implementation in routine diagnostic and a lower chance of interference between medium components and antimicrobial agents, supplemented CAMHB is recommended with an incubation time of 24 h.

  6. 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

  7. Multicenter evaluation of the MB/BACT system for susceptibility testing of Mycobacterium tuberculosis.

    PubMed

    Bemer, Pascale; Bodmer, Thomas; Munzinger, Juerg; Perrin, Monique; Vincent, Véronique; Drugeon, Henri

    2004-03-01

    The reliability of the MB/BACT system for susceptibility testing of Mycobacterium tuberculosis to pyrazinamide, rifampin, isoniazid, streptomycin, and ethambutol was compared to the BACTEC 460TB system. The proportion method was used to resolve discrepant results by an independent arbiter. Two interpretative methods were used, with an undiluted control (direct control) and a diluted control (10(-1) control). As no significant difference was observed between the two controls, the method with the direct control was adopted as the most accurate one. One hundred sixty-six strains were tested, with an overall agreement of 98.3%. After resolution of the 18 discrepant results by the proportion method, the sensitivity and specificity of the MB/BACT system were 100% for rifampin, isoniazid, and pyrazinamide. For ethambutol, sensitivity was 92.3% at the critical concentration and 33% at the high concentration, and specificity was 100% at both concentrations. For streptomycin, sensitivity was 100% at the critical concentration and 80% at the high concentration, and specificity was 98.6% at the critical concentration and 100% at the high concentration. The rifampin, isoniazid, streptomycin, and ethambutol susceptibility test results were obtained in 6.6 days with the MB/BACT versus 5 days with the BACTEC 460TB. The pyrazinamide susceptibility test results were obtained in 7.8 days with the MB/BACT, versus 6.7 days with the BACTEC 460TB. These data demonstrate that the fully automated MB/BACT system is a very reliable method for rapid susceptibility testing of M. tuberculosis against rifampin, isoniazid, and pyrazinamide. Sensitivity results have to be improved for ethambutol and streptomycin, especially at the high concentration.

  8. Multicenter Evaluation of the MB/BACT System for Susceptibility Testing of Mycobacterium tuberculosis

    PubMed Central

    Bemer, Pascale; Bodmer, Thomas; Munzinger, Juerg; Perrin, Monique; Vincent, Véronique; Drugeon, Henri

    2004-01-01

    The reliability of the MB/BACT system for susceptibility testing of Mycobacterium tuberculosis to pyrazinamide, rifampin, isoniazid, streptomycin, and ethambutol was compared to the BACTEC 460TB system. The proportion method was used to resolve discrepant results by an independent arbiter. Two interpretative methods were used, with an undiluted control (direct control) and a diluted control (10−1 control). As no significant difference was observed between the two controls, the method with the direct control was adopted as the most accurate one. One hundred sixty-six strains were tested, with an overall agreement of 98.3%. After resolution of the 18 discrepant results by the proportion method, the sensitivity and specificity of the MB/BACT system were 100% for rifampin, isoniazid, and pyrazinamide. For ethambutol, sensitivity was 92.3% at the critical concentration and 33% at the high concentration, and specificity was 100% at both concentrations. For streptomycin, sensitivity was 100% at the critical concentration and 80% at the high concentration, and specificity was 98.6% at the critical concentration and 100% at the high concentration. The rifampin, isoniazid, streptomycin, and ethambutol susceptibility test results were obtained in 6.6 days with the MB/BACT versus 5 days with the BACTEC 460TB. The pyrazinamide susceptibility test results were obtained in 7.8 days with the MB/BACT, versus 6.7 days with the BACTEC 460TB. These data demonstrate that the fully automated MB/BACT system is a very reliable method for rapid susceptibility testing of M. tuberculosis against rifampin, isoniazid, and pyrazinamide. Sensitivity results have to be improved for ethambutol and streptomycin, especially at the high concentration. PMID:15004049

  9. Comparative erythromycin and tylosin susceptibility testing of streptococci from bovine mastitis.

    PubMed

    Entorf, Monika; Feßler, Andrea T; Kaspar, Heike; Kadlec, Kristina; Peters, Thomas; Schwarz, Stefan

    2016-10-15

    Tylosin, a 16-membered macrolide, is - besides other indications - used for the treatment of bovine mastitis. So far, there is only limited information available on the tylosin susceptibility of streptococci isolated from mastitis. The aim of the present study was to comparatively investigate 303 streptococci from bovine mastitis, including 101 Streptococcus agalactiae, 100 Streptococcus dysgalactiae and 102 Streptococcus uberis, for their tylosin and erythromycin susceptibility by broth microdilution and agar disk diffusion. Both tests followed the recommendations of the Clinical and Laboratory Standards Institute (CLSI). For erythromycin, the results were interpreted using the CLSI-approved clinical breakpoints. Moreover, erythromycin-resistant isolates were tested for the presence of macrolide resistance genes and for inducible macrolide resistance. In general, both testing methods showed a good correlation for the three streptococcal species, although for the erythromycin susceptibility testing 11 S. uberis isolates fell into the very major error category. All but one of the erythromycin-resistant isolates harbored at least one macrolide resistance gene, with the erm(B) gene being most common. Moreover, single isolates of S. agalactiae and S. dysgalactiae proved to be inducibly macrolide-resistant. Since inducible macrolide resistance can easily switch to constitutive resistance, tylosin should not be used for the treatment of infections caused by inducibly resistant streptococci.

  10. American Society of Clinical Oncology Policy Statement Update: Genetic and Genomic Testing for Cancer Susceptibility.

    PubMed

    Robson, Mark E; Bradbury, Angela R; Arun, Banu; Domchek, Susan M; Ford, James M; Hampel, Heather L; Lipkin, Stephen M; Syngal, Sapna; Wollins, Dana S; Lindor, Noralane M

    2015-11-01

    The American Society of Clinical Oncology (ASCO) has long affirmed that the recognition and management of individuals with an inherited susceptibility to cancer are core elements of oncology care. ASCO released its first statement on genetic testing in 1996 and updated that statement in 2003 and 2010 in response to developments in the field. In 2014, the Cancer Prevention and Ethics Committees of ASCO commissioned another update to reflect the impact of advances in this area on oncology practice. In particular, there was an interest in addressing the opportunities and challenges arising from the application of massively parallel sequencing-also known as next-generation sequencing-to cancer susceptibility testing. This technology introduces a new level of complexity into the practice of cancer risk assessment and management, requiring renewed effort on the part of ASCO to ensure that those providing care to patients with cancer receive the necessary education to use this new technology in the most effective, beneficial manner. The purpose of this statement is to explore the challenges of new and emerging technologies in cancer genetics and provide recommendations to ensure their optimal deployment in oncology practice. Specifically, the statement makes recommendations in the following areas: germline implications of somatic mutation profiling, multigene panel testing for cancer susceptibility, quality assurance in genetic testing, education of oncology professionals, and access to cancer genetic services.

  11. Identification and antimicrobial susceptibility testing of Staphylococcus vitulinus by the BD phoenix automated microbiology system.

    PubMed

    Cirković, Ivana; Hauschild, Tomasz; Jezek, Petr; Dimitrijević, Vladimir; Vuković, Dragana; Stepanović, Srdjan

    2008-08-01

    This study evaluated the performance of the BD Phoenix system for the identification (ID) and antimicrobial susceptibility testing (AST) of Staphylococcus vitulinus. Of the 10 S. vitulinus isolates included in the study, 2 were obtained from the Czech Collection of Microorganisms, 5 from the environment, 2 from human clinical samples, and 1 from an animal source. The results of conventional biochemical and molecular tests were used for the reference method for ID, while antimicrobial susceptibility testing performed in accordance with Clinical and Laboratory Standards Institute recommendations and PCR for the mecA gene were the reference for AST. Three isolates were incorrectly identified by the BD Phoenix system; one of these was incorrectly identified to the genus level, and two to the species level. The results of AST by the BD Phoenix system were in agreement with those by the reference method used. While the results of susceptibility testing compared favorably, the 70% accuracy of the Phoenix system for identification of this unusual staphylococcal species was not fully satisfactory.

  12. Electromagnetic Compatibility Testing for Conducted Susceptibility Along Interconnecting Signal Lines. Final report

    SciTech Connect

    Ewing, P. D.; Wood, R. T.; Korsah, K.; Shourbaji, A. A.; Wilson, T. L.; Beets, B. M.

    2002-07-31

    This document presents recommendations and the associated technical basis for addressing the effects of conducted electromagnetic interference (EMI) and radio-frequency interference (RFI) along interconnecting signal lines in safety-related instrumentation and control (I&C) systems. Oak Ridge National Laboratory has been engaged in assisting the U.S. Nuclear Regulatory Commission Office of Nuclear Regulatory Research in developing the technical basis for regulatory guidance on EMIIRFI immunity and power surge withstand capability (SWC). Previous research efforts have provided recommendations on (1) electromagnetic compatibility design and installation practices, (2) the endorsement of EMI/RFI and SWC test criteria and test methods, (3) the determination of ambient electromagnetic conditions at nuclear power plants, and (4) the development of recommended electromagnetic operating envelopes applicable to locations where safety-related I&C systems will be installed. The current research focuses on the susceptibility of l&C systems to conducted EMIIRFI along interconnecting signal lines. Coverage of signal line susceptibility was identified as an open issue in previous research on establishing the technical basis for EMIIRFI and SWC in safety-related I&C systems. Research results provided in this report will be used to establish the technical basis for endorsing U.S. Department of Defense and European Committee for Electrotechnical Standardization test criteria and test methods that address signal-line susceptibility. In addition, recommendations on operating envelopes are presented based on available technical information.

  13. Testing of susceptibility of Mycobacterium tuberculosis to isoniazid and rifampin by mycobacterium growth indicator tube method.

    PubMed Central

    Walters, S B; Hanna, B A

    1996-01-01

    We tested isolates of Mycobacterium tuberculosis recovered from 117 patients for their susceptibilities to isoniazid (INH) and rifampin (RIF) by the Centers for Disease Control and Prevention's disk modification of the indirect method of proportions (MOP) test and a three-tube mycobacteria growth indicator tube (MGIT; BBL) antimycobacterial susceptibility test (AST). Sixty-seven of the M. tuberculosis isolates were recovered from Lowenstein-Jensen (BBL) subcultures, and 50 of the isolates were recovered from MGIT cultures of samples from various body sites. For the MGIT AST method, 0.5 ml of test organism suspension was inoculated into an MGIT with 0.1 micrograms of INH per ml, an MGIT with 1.0 micrograms of RIF per ml, and growth control MGIT. The tubes were incubated at 37 degrees C and were examined daily. The MGIT AST results were interpreted as follows: susceptible if the tubes containing INH or RIF did not fluoresce within 2 days of the time that the positive growth control fluoresced and resistant if the tubes containing INH or RIF did fluoresce within 2 days of the time that the positive growth control fluoresced. The mean time fluorescence for the positive growth control was 5.5 days. The two methods were in agreement for 114 of the 117 isolates from patients, while for 3 isolates there were minor discordant results. PMID:8735121

  14. Lumbar disc herniations: the predictive value of the Health Attribution Test (HAT) and the Minnesota Multiphasic Personality Inventory (MMPI).

    PubMed

    Herron, L D; Turner, J A; Weiner, P

    1988-01-01

    Ninety-one patients who were treated for lumbar disc herniation with chymopapain chemonucleolysis were evaluated preoperatively by means of the Health Attribution Test (HAT) and the Minnesota Multiphasic Personality Inventory (MMPI). There were 54 good, 10 fair, and 27 poor results after chemo-nucleolysis. Nineteen patients subsequently underwent lumbar laminectomy and discectomy and the ultimate outcome for the entire series including these laminectomy patients was 66 good, 10 fair, and 15 poor results. The fair/poor chemonucleolysis outcome patients scored significantly lower than did the good outcome patients on the HAT Powerful Others and significantly higher on the Chance scale. Patients with fair or poor outcomes after chemonucleolysis only scored significantly higher on the Hypochondriasis, Hysteria, Psychopathic Deviate, Paranoia, and Hypomania scales in preoperative MMPI testing. Good versus fair/poor ultimate outcome patients differed significantly on preoperative MMPI Hypochondriasis, Hysteria, Psychopathic Deviate, Paranoia, Psychasthenia, Schizophrenia, Hypomania, and Social Introversion scales. These groups also differed significantly on preoperative HAT Internal and Chance scales. Further analyses found the MMPI to be a slightly better predictor of chemonucleolysis outcome and much better predictor of ultimate outcome than the HAT.

  15. 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

  16. [Comparison of microdilution method and Phoenix automated system for testing antimicrobial susceptibilities of Enterococcus strains].

    PubMed

    Gülmez, Dolunay; Hasçelik, Gülşen

    2011-01-01

    Enterococcus spp. are important pathogens which are intrinsically resistant to most of the commonly used antimicrobial agents such as aminoglycosides and cephalosporins. Accurate determination of resistance is important to ensure appropriate antimicrobial therapy. This study was undertaken to compare the susceptibility results obtained by Phoenix system (Becton Dickinson, USA) with reference microdilution method. We included 1248 Enterococcus spp. (903 Enterococcus faecalis, 345 Enterococcus faecium) strains isolated from clinical samples between 2005-2007 in routine microbiology laboratory of Hacettepe University Hospital. The strains were identified and the antimicrobial susceptibilities were determined by the Phoenix system. Antimicrobial susceptibilities to ampicillin, teicoplanin, vancomycin, gentamicin and streptomycin were also studied by microdilution method according to Clinical and Laboratory Standards Institute (CLSI) guidelines. Evaluation revealed excellent agreement for all of the antibiotics with category agreement rates of > 97%. Among 1248 strains, 76 revealed discordant results. Very major error rates were 1.5% for ampicillin, 1.3% for gentamicin, and 0.9% for streptomycin. Major error rates were 1.4% for streptomycin, 0.6% for ampicillin and vancomycin and 0.3% for gentamicin. Minor error rates were found as 0.2% for vancomycin, and 0.1% for teicoplanin. Resistance rates obtained by microdilution were as follows; high level streptomycin 44%, high level gentamicin 29.7%, ampicillin 25.6%, vancomycin 2.2% and teicoplanin 2.2%. Resistance rates were higher in E.faecium than E.faecalis and 96.4% of the vancomycin resistant enterococcus isolates were identified as E.faecium. In conclusion, based on the data obtained, Phoenix system is reliable for testing susceptibilities of Enterococcus spp. to these antimicrobials. Since isolation of vancomycin resistant enterococci has an important impact in terms of hospital infection control, vancomycin

  17. What's in a Name? The Impact of Accurate Staphylococcus pseudintermedius Identification on Appropriate Antimicrobial Susceptibility Testing

    PubMed Central

    2016-01-01

    Bacteria in the Staphylococcus intermedius group, including Staphylococcus pseudintermedius, often encode mecA-mediated methicillin resistance. Reliable detection of this phenotype for proper treatment and infection control decisions requires that these coagulase-positive staphylococci are accurately identified and specifically that they are not misidentified as S. aureus. As correct species level bacterial identification becomes more commonplace in clinical laboratories, one can expect to see changes in guidance for antimicrobial susceptibility testing and interpretation. The study by Wu et al. in this issue (M. T. Wu, C.-A. D. Burnham, L. F. Westblade, J. Dien Bard, S. D. Lawhon, M. A. Wallace, T. Stanley, E. Burd, J. Hindler, R. M. Humphries, J Clin Microbiol 54:535–542, 2016, http://dx.doi.org/10.1128/JCM.02864-15) highlights the impact of robust identification of S. intermedius group organisms on the selection of appropriate antimicrobial susceptibility testing methods and interpretation. PMID:26763965

  18. Development of an Accelerated Test Method for the Determination of Susceptibility to Atmospheric Corrosion

    NASA Technical Reports Server (NTRS)

    Ambrose, John R.

    1991-01-01

    The theoretical rationale is presented for use of a repetitive cyclic current reversal voltammetric technique for characterization of localized corrosion processes, including atmospheric corrosion. Applicability of this proposed experimental protocol is applied to characterization of susceptibility to crevice and pitting corrosion, atmospheric corrosion and stress corrosion cracking. Criteria upon which relative susceptibility is based were determined and tested using two iron based alloys commonly in use at NASA-Kennedy; A36 (a low carbon steel) and 4130 (a low alloy steel). Practicality of the procedure was demonstrated by measuring changes in anodic polarization behavior during high frequency current reversal cycles of 25 cycles per second with 1 mA/sq cm current density amplitude in solutions containing Cl anions. The results demonstrated that, due to excessive polarization which affects conductivity of barrier corrosion product layers, A36 was less resistant to atmospheric corrosion than its 4130 counterpart; behavior which was also demonstrated during exposure tests.

  19. Proposed interpretive criteria and quality control parameters for ofloxacin susceptibility testing of Neisseria gonorrhoeae.

    PubMed Central

    Fuchs, P C; Barry, A L; Baker, C; Murray, P R; Washington, J A

    1992-01-01

    A multilaboratory study designed to determine the in vitro susceptibility criteria and quality control parameters for ofloxacin against Neisseria gonorrhoeae was conducted according to the guidelines of the National Committee for Clinical Laboratory Standards. Proposed susceptibility breakpoints are MICs of less than or equal to 0.25 microgram/ml for the agar dilution test and greater than or equal to 31 mm for the disk diffusion test. A category for resistance could not be defined. Proposed acceptable quality control MICs for N. gonorrhoeae ATCC 49226 and Staphylococcus aureus ATCC 29213 range from 0.004 to 0.03 microgram/ml and 0.25 to 1.0 microgram/ml, respectively. With 5-micrograms ofloxacin disks, acceptable inhibitory zone diameters for S. aureus ATCC 25923 and the N. gonorrhoeae control strains range from 22 to 27 mm and 43 to 51 mm, respectively. PMID:1572960

  20. Effect of Susceptibility Testing Conditions on the In Vitro Antibacterial Activity of ETX0914.

    PubMed

    Giacobbe, Robert A; Huband, Michael D; deJonge, Boudewijn L M; Bradford, Patricia A

    2017-02-01

    The effect of various conditions including pH, inoculum, temperature, atmosphere, divalent cations, and several body fluids on the in vitro activity of the novel antibacterial spiropyrimidinetrione ETX0914 in standard susceptibility tests was investigated against several species. None of the parameters investigated affected the activity of ETX0914, with the exception of pH. Whereas the MIC values for ETX0914 with S. aureus, E. faecalis, and E. coli did not change when the pH of the growth medium was varied from 5 to 8, they did increase at least 8-fold at pH values above 8. This loss of activity can be attributed to the deprotonation of the molecule at elevated pH. The data suggest that routine susceptibility testing with ETX0914 should result in reproducible MIC values.

  1. Experimental Study of the Rolling-Sliding Contact Conditions in a PA66/STEEL Gear Using Twin-Disc Test Rig: Friction and Wear Analysis

    NASA Astrophysics Data System (ADS)

    Mbarek, Meftah; Rhaiem, Sadok; Kharrat, Mohamed; Dammak, Maher

    2015-09-01

    This study investigates the effects of sliding ratio on the tribological response of the contact between the teeth of a metal/polymer gear in the regions close to the pitch point. For this purpose, a new twin-disc test rig was developed on the basis of two discs of different diameters rotating one above the other at the same angular speed. Two different materials were used: non-alloyed structural steel (C45) and polyamide (PA66). The effect of the slip ratio (4%, 12%, 20% and 28%) was studied at a constant pressure of 34 MPa and a constant angular speed of 300 rpm. In addition, the contact conditions were controlled with measurements of the two discs surface temperatures. The results indicate that the wear and the friction are closely related to the contact temperature generated by the sliding phenomenon. At low slip ratio (4% and 12%), the coefficient of friction and the temperature are characterized by a quasi-linear increase with time, and the wear increases slowly. At higher slip ratio (20% and 28%), the coefficient of friction and the temperature presents a steady state, and the wear increases dramatically. During the test, a film of transferred PA66 is formed on the steel surface causing the development of adhesive interactions between the contacting discs which increase the friction coefficient and the contact temperature. The high thermal conductivity of steel as compared to that of the polymer can reduce enormously the contact temperature generated by the sliding process.

  2. Novel Antibiotic Susceptibility Tests by the ATP-Bioluminescence Method Using Filamentous Cell Treatment

    PubMed Central

    Hattori, Noriaki; Nakajima, Moto-O; O’Hara, Koji; Sawai, Tetsuo

    1998-01-01

    Antimicrobial susceptibility testing by the ATP-bioluminescence method has been noted for its speed; it provides susceptibility results within 2 to 5 h. However, several disagreements between the ATP method and standard methodology have been reported. The present paper describes a novel ATP method in a 3.5-h test which overcomes these deficiencies through the elimination of false-resistance discrepancies in tests on gram-negative bacteria with β-lactam agents. In our test model using Pseudomonas aeruginosa and piperacillin, it was shown that ATP in filamentous cells accounted for the false resistance. We found that 0.5% 2-amino-2-methyl-1,3-propanediol (AMPD) extracted ATP from the filamentous cells without affecting normal cells and that 0.3 U of adenosine phosphate deaminase (APDase)/ml simultaneously digested the extracted ATP. We used the mixture of these reagents for the pretreatment of cells in a procedure we named filamentous cell treatment, prior to ATP measurements. This novel ATP method with the filamentous cell treatment eliminated false-resistance discrepancies in tests on P. aeruginosa with β-lactam agents, including piperacillin, cefoperazone, aztreonam, imipenem-cilastatin, ceftazidime, and cefsulodin. Furthermore, this novel methodology produced results which agreed with those of the standard microdilution method in other tests on gram-negative and gram-positive bacteria, including P. aeruginosa, Escherichia coli, Staphylococcus aureus, and Enterococcus faecalis, for non-β-lactam agents, such as fosfomycin, ofloxacin, minocycline, and aminoglycosides. MICs obtained by the novel ATP method were also in agreement with those obtained by the agar dilution method of susceptibility testing. From these results, it was shown that the novel ATP method could be used successfully to test the activities of antimicrobial agents with the elimination of the previously reported discrepancies. PMID:9624485

  3. Evaluation of a New System, VITEK 2, for Identification and Antimicrobial Susceptibility Testing of Enterococci

    PubMed Central

    Garcia-Garrote, Fernando; Cercenado, Emilia; Bouza, Emilio

    2000-01-01

    We evaluated the new automated VITEK 2 system (bioMérieux) for the identification and antimicrobial susceptibility testing of enterococci. The results obtained with the VITEK 2 system were compared to those obtained by reference methods: standard identification by the scheme of Facklam and Sahm [R. R. Facklam and D. F. Sahm, p. 308–314, in P. R. Murray et al., ed., Manual of Clinical Microbiology, 6th ed., 1995] and with the API 20 STREP system and, for antimicrobial susceptibility testing, broth microdilution and agar dilution methods by the procedures of the National Committee for Clinical Laboratory Standards. The presence of vanA and vanB genes was determined by PCR. A total of 150 clinical isolates were studied, corresponding to 60 Enterococcus faecalis, 55 Enterococcus faecium, 26 Enterococcus gallinarum, 5 Enterococcus avium, 2 Enterococcus durans, and 2 Enterococcus raffinosus isolates. Among those isolates, 131 (87%) were correctly identified to the species level with the VITEK 2 system. Approximately half of the misidentifications were for E. faecium with low-level resistance to vancomycin, identified as E. gallinarum or E. casseliflavus; however, a motility test solved the discrepancies and increased the agreement to 94%. Among the strains studied, 66% were vancomycin resistant (57 VanA, 16 VanB, and 26 VanC strains), 23% were ampicillin resistant (MICs, ≥16 μg/ml), 31% were high-level gentamicin resistant, and 45% were high-level streptomycin resistant. Percentages of agreement for susceptibility and resistance to ampicillin, vancomycin, and teicoplanin and for high-level gentamicin resistance and high-level streptomycin resistance were 93, 95, 97, 97, and 96%, respectively. The accuracy of identification and antimicrobial susceptibility testing of enterococci with the VITEK 2 system, together with the significant reduction in handling time, will have a positive impact on the work flow of the clinical microbiology laboratory. PMID:10834961

  4. Evaluation of a new system, VITEK 2, for identification and antimicrobial susceptibility testing of enterococci.

    PubMed

    Garcia-Garrote, F; Cercenado, E; Bouza, E

    2000-06-01

    We evaluated the new automated VITEK 2 system (bioMérieux) for the identification and antimicrobial susceptibility testing of enterococci. The results obtained with the VITEK 2 system were compared to those obtained by reference methods: standard identification by the scheme of Facklam and Sahm [R. R. Facklam and D. F. Sahm, p. 308-314, in P. R. Murray et al., ed., Manual of Clinical Microbiology, 6th ed., 1995] and with the API 20 STREP system and, for antimicrobial susceptibility testing, broth microdilution and agar dilution methods by the procedures of the National Committee for Clinical Laboratory Standards. The presence of vanA and vanB genes was determined by PCR. A total of 150 clinical isolates were studied, corresponding to 60 Enterococcus faecalis, 55 Enterococcus faecium, 26 Enterococcus gallinarum, 5 Enterococcus avium, 2 Enterococcus durans, and 2 Enterococcus raffinosus isolates. Among those isolates, 131 (87%) were correctly identified to the species level with the VITEK 2 system. Approximately half of the misidentifications were for E. faecium with low-level resistance to vancomycin, identified as E. gallinarum or E. casseliflavus; however, a motility test solved the discrepancies and increased the agreement to 94%. Among the strains studied, 66% were vancomycin resistant (57 VanA, 16 VanB, and 26 VanC strains), 23% were ampicillin resistant (MICs, >/=16 microgram/ml), 31% were high-level gentamicin resistant, and 45% were high-level streptomycin resistant. Percentages of agreement for susceptibility and resistance to ampicillin, vancomycin, and teicoplanin and for high-level gentamicin resistance and high-level streptomycin resistance were 93, 95, 97, 97, and 96%, respectively. The accuracy of identification and antimicrobial susceptibility testing of enterococci with the VITEK 2 system, together with the significant reduction in handling time, will have a positive impact on the work flow of the clinical microbiology laboratory.

  5. Automated reading of a microtitre plate: preliminary evaluation in antimicrobial susceptibility tests and Enterobacteriaceae identification.

    PubMed Central

    Courcol, R J; Deleersnyder, H; Roussel-Delvallez, M; Martin, G R

    1983-01-01

    An automated microELISA Reader was evaluated for its ability to read and interpret microtitre plates. A total of 309 microtitre plates were investigated by automated and visual methods. There was disagreement between the methods in one hundred and twelve (0.6%) wells. However agreements between the two methods for susceptibility tests and Enterobacteriaceae identification were respectively 98.8% and 89.3%. PMID:6338058

  6. Antifungal Susceptibility Testing of Fluconazole by Flow Cytometry Correlates with Clinical Outcome

    PubMed Central

    Wenisch, Christoph; Moore, Caroline B.; Krause, Robert; Presterl, Elisabeth; Pichna, Peter; Denning, David W.

    2001-01-01

    Susceptibility testing of fungi by flow cytometry (also called fluorescence-activated cell sorting [FACS]) using vital staining with FUN-1 showed a good correlation with the standard M27-A procedure for assessing MICs. In this study we determined MICs for blood culture isolates from patients with candidemia by NCCLS M27-A and FACS methods and correlated the clinical outcome of these patients with in vitro antifungal resistance test results. A total of 24 patients with candidemia for whom one or more blood cultures were positive for a Candida sp. were included. Susceptibility testing was performed by NCCLS M27-A and FACS methods. The correlation of MICs (NCCLS M27-A and FACS) and clinical outcome was calculated. In 83% of the cases, the MICs of fluconazole determined by FACS were within 1 dilution of the MICs determined by the NCCLS M27-A method. For proposed susceptibility breakpoints, there was 100% agreement between the M27-A and FACS methods. In the FACS assay, a fluconazole MIC of <1 μg/ml was associated with cure (P < 0.001) whereas an MIC of ≥1 μg/ml was associated with death (P < 0.001). The M27-A-derived fluconazole MICs did not correlate with outcome (P = 1 and P = 0.133). PMID:11427554

  7. A microfluidic device for antimicrobial susceptibility testing based on a broth dilution method.

    PubMed

    Lee, Wen-Bin; Fu, Chien-Yu; Chang, Wen-Hsin; You, Huey-Ling; Wang, Chih-Hung; Lee, Mel S; Lee, Gwo-Bin

    2017-01-15

    Bacterial resistance to antimicrobial compounds is increasing at a faster rate than the development of new antibiotics; this represents a critical challenge for clinicians worldwide. Normally, the minimum inhibitory concentration of an antibiotic, the dosage at which bacterial growth is thwarted, provides an effective quantitative measure for antimicrobial susceptibility testing, and determination of minimum inhibitory concentration is conventionally performed by either a serial broth dilution method or with the commercially available Etest(®) (Biomerieux, France) kit. However, these techniques are relatively labor-intensive and require a significant amount of training. In order to reduce human error and increase operation simplicity, a simple microfluidic device that can perform antimicrobial susceptibility testing automatically via a broth dilution method to accurately determine the minimum inhibitory concentration was developed herein. As a proof of concept, wild-type (ATCC 29212) and vancomycin-resistant Enterococcus cells were incubated at five different vancomycin concentrations on-chip, and the sample injection, transport, and mixing processes occurred within five reaction chambers and three reagent chambers via the chip's automatic dispensation and dilution functions within nine minutes. The minimum inhibitory concentration values measured after 24h of antibiotic incubation were similar to those calculated using Etest(®). With its high flexibility, reliability, and portability, the developed microfluidic device provides a simple method for antimicrobial susceptibility testing in an automated format that could be implemented for clinical and point-of-care applications.

  8. 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

  9. Process Analysis of Variables for Standardization of Antifungal Susceptibility Testing of Nonfermentative Yeasts ▿

    PubMed Central

    Zaragoza, Oscar; Mesa-Arango, Ana C.; Gómez-López, Alicia; Bernal-Martínez, Leticia; Rodríguez-Tudela, Juan Luis; Cuenca-Estrella, Manuel

    2011-01-01

    Nonfermentative yeasts, such as Cryptococcus spp., have emerged as fungal pathogens during the last few years. However, standard methods to measure their antifungal susceptibility (antifungal susceptibility testing [AST]) are not completely reliable due to the impaired growth of these yeasts in standard media. In this work, we have compared the growth kinetics and the antifungal susceptibilities of representative species of nonfermentative yeasts such as Cryptococcus neoformans, Cryptococcus gattii, Cryptococcus albidus, Rhodotorula spp., Yarrowia lipolytica, Geotrichum spp., and Trichosporon spp. The effect of the growth medium (RPMI medium versus yeast nitrogen base [YNB]), glucose concentration (0.2% versus 2%), nitrogen source (ammonium sulfate), temperature (30°C versus 35°C), shaking, and inoculum size (103, 104, and 105 cells) were analyzed. The growth rate, lag phase, and maximum optical density were obtained from each growth experiment, and after multivariate analysis, YNB-based media demonstrated a significant improvement in the growth of yeasts. Shaking, an inoculum size of 105 CFU/ml, and incubation at 30°C also improved the growth kinetics of organisms. Supplementation with ammonium sulfate and with 2% glucose did not have any effect on growth. We also tested the antifungal susceptibilities of all the isolates by the reference methods of the CLSI and EUCAST, the EUCAST method with shaking, YNB under static conditions, and YNB with shaking. MIC values obtained under different conditions showed high percentages of agreement and significant correlation coefficient values between them. MIC value determinations according to CLSI and EUCAST standards were rather complicated, since more than half of isolates tested showed a limited growth index, hampering endpoint determinations. We conclude that AST conditions including YNB as an assay medium, agitation of the plates, reading after 48 h of incubation, an inoculum size of 105 CFU/ml, and incubation at 30

  10. Process analysis of variables for standardization of antifungal susceptibility testing of nonfermentative yeasts.

    PubMed

    Zaragoza, Oscar; Mesa-Arango, Ana C; Gómez-López, Alicia; Bernal-Martínez, Leticia; Rodríguez-Tudela, Juan Luis; Cuenca-Estrella, Manuel

    2011-04-01

    Nonfermentative yeasts, such as Cryptococcus spp., have emerged as fungal pathogens during the last few years. However, standard methods to measure their antifungal susceptibility (antifungal susceptibility testing [AST]) are not completely reliable due to the impaired growth of these yeasts in standard media. In this work, we have compared the growth kinetics and the antifungal susceptibilities of representative species of nonfermentative yeasts such as Cryptococcus neoformans, Cryptococcus gattii, Cryptococcus albidus, Rhodotorula spp., Yarrowia lipolytica, Geotrichum spp., and Trichosporon spp. The effect of the growth medium (RPMI medium versus yeast nitrogen base [YNB]), glucose concentration (0.2% versus 2%), nitrogen source (ammonium sulfate), temperature (30°C versus 35°C), shaking, and inoculum size (10(3), 10(4), and 10(5) cells) were analyzed. The growth rate, lag phase, and maximum optical density were obtained from each growth experiment, and after multivariate analysis, YNB-based media demonstrated a significant improvement in the growth of yeasts. Shaking, an inoculum size of 10(5) CFU/ml, and incubation at 30°C also improved the growth kinetics of organisms. Supplementation with ammonium sulfate and with 2% glucose did not have any effect on growth. We also tested the antifungal susceptibilities of all the isolates by the reference methods of the CLSI and EUCAST, the EUCAST method with shaking, YNB under static conditions, and YNB with shaking. MIC values obtained under different conditions showed high percentages of agreement and significant correlation coefficient values between them. MIC value determinations according to CLSI and EUCAST standards were rather complicated, since more than half of isolates tested showed a limited growth index, hampering endpoint determinations. We conclude that AST conditions including YNB as an assay medium, agitation of the plates, reading after 48 h of incubation, an inoculum size of 10(5) CFU/ml, and

  11. Public interest in predictive genetic testing, including direct-to-consumer testing, for susceptibility to major depression: preliminary findings.

    PubMed

    Wilde, Alex; Meiser, Bettina; Mitchell, Philip B; Schofield, Peter R

    2010-01-01

    The past decade has seen rapid advances in the identification of associations between candidate genes and a range of common multifactorial disorders. This paper evaluates public attitudes towards the complexity of genetic risk prediction in psychiatry involving susceptibility genes, uncertain penetrance and gene-environment interactions on which successful molecular-based mental health interventions will depend. A qualitative approach was taken to enable the exploration of the views of the public. Four structured focus groups were conducted with a total of 36 participants. The majority of participants indicated interest in having a genetic test for susceptibility to major depression, if it was available. Having a family history of mental illness was cited as a major reason. After discussion of perceived positive and negative implications of predictive genetic testing, nine of 24 participants initially interested in having such a test changed their mind. Fear of genetic discrimination and privacy issues predominantly influenced change of attitude. All participants still interested in having a predictive genetic test for risk for depression reported they would only do so through trusted medical professionals. Participants were unanimously against direct-to-consumer genetic testing marketed through the Internet, although some would consider it if there was suitable protection against discrimination. The study highlights the importance of general practitioner and public education about psychiatric genetics, and the availability of appropriate treatment and support services prior to implementation of future predictive genetic testing services.

  12. Self-assembled magnetic bead biosensor for measuring bacterial growth and antimicrobial susceptibility testing.

    PubMed

    Kinnunen, Paivo; McNaughton, Brandon H; Albertson, Theodore; Sinn, Irene; Mofakham, Sima; Elbez, Remy; Newton, Duane W; Hunt, Alan; Kopelman, Raoul

    2012-08-20

    Bacterial antibiotic resistance is one of the major concerns of modern healthcare worldwide, and the development of rapid, growth-based, antimicrobial susceptibility tests is key for addressing it. The cover image shows a self-assembled asynchronous magnetic bead rotation (AMBR) biosensor developed for rapid detection of bacterial growth. Using the biosensors, the minimum inhibitory concentration of a clinical E. coli isolate can be measured within two hours, where currently tests take 6-24 hours. A 16-well prototype is also constructed for simple and robust observation of the self-assembled AMBR biosensors.

  13. Combination antimicrobial susceptibility testing of Burkholderia cepacia complex: significance of species.

    PubMed

    Abbott, Felicity K; Milne, Kathleen E N; Stead, David A; Gould, Ian M

    2016-11-01

    The Burkholderia cepacia complex (Bcc) is notorious for the life-threatening pulmonary infections it causes in patients with cystic fibrosis. The multidrug-resistant nature of Bcc and differing infective Bcc species make the design of appropriate treatment regimens challenging. Previous synergy studies have failed to take account of the species of Bcc isolates. Etest methodology was used to facilitate minimum inhibitory concentration (MIC) and antimicrobial combination testing on 258 isolates of Bcc, identified to species level by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF/MS). The most active antimicrobials were trimethoprim/sulphamethoxazole, doxycycline and minocycline (52.5%, 46.4% and 45.9% of isolates susceptible, respectively). Synergy was observed in 9.2% of the 1799 combinations tested; the most common synergistic combinations were tobramycin + ceftazidime, meropenem + tobramycin and levofloxacin + piperacillin/tazobactam (35.4%, 32.3% and 22.2% synergy, respectively). Antimicrobial susceptibility analysis revealed differences between Burkholderia cenocepacia and Burkholderia multivorans. Disparity in clinical outcome during infection with these two micro-organisms necessitates further investigation into the clinical outcomes of treatment regimens in light of species identification and in vitro antimicrobial susceptibility studies.

  14. Multicenter Evaluation of the Mycobacteria Growth Indicator Tube for Testing Susceptibility of Mycobacterium tuberculosis to First-Line Drugs

    PubMed Central

    Rüsch-Gerdes, Sabine; Domehl, Cornelia; Nardi, Giampietro; Gismondo, Maria Rita; Welscher, Hans-Martin; Pfyffer, Gaby E.

    1999-01-01

    In a multicenter study involving three reference centers for mycobacteria, the reliability of the Mycobacteria Growth Indicator Tube (MGIT) for rapid antimicrobial susceptibility testing (AST) of Mycobacterium tuberculosis was evaluated and compared to the radiometric method (BACTEC 460TB). Test cultures for which the results of the MGIT and BACTEC 460TB tests were discordant were checked by the conventional proportion method on solid medium. Four hundred forty-one isolates have been tested for susceptibility to isoniazid (INH), rifampin (RMP), ethambutol (EMB), and streptomycin (SM). Discrepant results were obtained for three isolates (0.7%) with INH (susceptible by MGIT, resistant by BACTEC 460TB), for four isolates (0.9%) with RMP (susceptible by MGIT, resistant by BACTEC 460TB), for six isolates (1.9%) with EMB (four susceptible by MGIT, resistant by BACTEC 460TB; two resistant by MGIT, susceptible by BACTEC 460TB), and for four isolates (0.9%) with SM (two susceptible by MGIT, resistant by BACTEC 460TB; two resistant by MGIT, susceptible by BACTEC 460TB). When cultures with discordant results were tested by the conventional proportion method, about half of the cultures yielded results similar to the BACTEC 460TB results, while the other half yielded results similar to the MGIT results. Turnaround times were 3 to 14 days (median, 8.8 days) for MGIT and 3 to 15 days (median, 7.8 days) for BACTEC 460TB. There was no statistically significant difference between the susceptibility testing results of the two methods (P > 0.05). These data demonstrate that the MGIT system is an accurate, nonradiometric alternative to the BACTEC 460TB method for rapid susceptibility testing of M. tuberculosis. PMID:9854062

  15. Rapid antimicrobial susceptibility testing with electrokinetics enhanced biosensors for diagnosis of acute bacterial infections.

    PubMed

    Liu, Tingting; Lu, Yi; Gau, Vincent; Liao, Joseph C; Wong, Pak Kin

    2014-11-01

    Rapid pathogen detection and antimicrobial susceptibility testing (AST) are required in diagnosis of acute bacterial infections to determine the appropriate antibiotic treatment. Molecular approaches for AST are often based on the detection of known antibiotic resistance genes. Phenotypic culture analysis requires several days from sample collection to result reporting. Toward rapid diagnosis of bacterial infection in non-traditional healthcare settings, we have developed a rapid AST approach that combines phenotypic culture of bacterial pathogens in physiological samples and electrochemical sensing of bacterial 16S rRNA. The assay determines the susceptibility of pathogens by detecting bacterial growth under various antibiotic conditions. AC electrokinetic fluid motion and Joule heating induced temperature elevation are optimized to enhance the sensor signal and minimize the matrix effect, which improve the overall sensitivity of the assay. The electrokinetics enhanced biosensor directly detects the bacterial pathogens in blood culture without prior purification. Rapid determination of the antibiotic resistance profile of Escherichia coli clinical isolates is demonstrated.

  16. New insights into the mechanism of action of pyrazinamide, implications for susceptibility testing, and future regimens.

    PubMed

    Anthony, Richard M; den Hertog, Alice; Mansjö, Mikael; Werngren, Jim

    2016-12-01

    Pyrazinamide (PZA) is included in the 2016 World Health Organization multidrug-resistant tuberculosis treatment guidelines and is a key component of most ongoing clinical trials investigating novel antibiotic combinations. PZA resistance is associated with worse tuberculosis treatment outcomes. Unfortunately, for such an important drug, phenotypic susceptibility testing is extremely challenging. The exacting bacterial growth conditions required to induce susceptibility to the drug reduce the accuracy of the susceptibility assay, even in experienced laboratories, and widespread testing is not performed. This situation is unacceptable for such a valuable and important drug. A more complete understanding of the mechanism of action of PZA would be expected to lead to improvements in this situation. Although the exact mechanism of action of PZA is not known yet, it is widely accepted that PZA is a prodrug requiring transformation to pyrazinoic acid, the active form, by the mycobacterial enzyme encoded by the pncA gene. Most clinical resistance indeed appears to be a result of a diverse range of mutations in this gene and sequencing of the pncA gene has been shown to have excellent predictive power for PZA resistance. The wider availably of pncA sequencing in combination with databases of the phenotypic implications of these mutations has helped make genetic testing for PZA resistance a practical proposition. For the past decades, it has been generally accepted that an extracellular low pH is required for PZA activity but work in our laboratory [1] and others [2] has recently challenged this assumption. Alternative bacterial stresses, apart from a reduced pH of the growth media (such as reduced temperature), can also induce a PZA-susceptible phenotype. The characterization of spontaneous in vitro-resistant pyrazinoic acid mutants selected under neutral pH conditions suggests a key role for the pantothenate/coenzyme A biosynthetic pathway. This has profound implications

  17. Patients' understanding of genetic susceptibility testing in mainstream medicine: qualitative study on thrombophilia

    PubMed Central

    Saukko, Paula M; Ellard, Sian; Richards, Suzanne H; Shepherd, Maggie H; Campbell, John L

    2007-01-01

    Background UK and US policy initiatives have suggested that, in the future, patients and clinicians in mainstream medicine could use genetic information to prevent common illnesses. There are no studies on patients' experience and understanding of the process of testing for common genetic susceptibilities in mainstream medicine. Methods Qualitative interviews with 42 individuals who had undergone testing for a genetic susceptibility for deep vein thrombosis in primary and secondary care in the UK. Results Some participants, often from higher social classes, had a good understanding of the test and its implications. They had often sought additional information on thrombophilia from relatives and from the Internet. Others, often from less privileged backgrounds, had a poorer understanding of the test – seven individuals were unaware of having had the genetic test. Features of genetic information led to misunderstandings: (i) at referral, (ii) when communicating results, and (iii) when making sense of the implications of testing. Participants' accounts indicated that non-specialist doctors may feel obliged to refer a patient for a genetic test they know little about, because a patient requests it after a relative had tested positive. Sometimes a referral for a genetic test was lost under information overload when multiple tests and issues were considered. The inconsistent and informal ways of communicating test results – for example by phone – in mainstream medicine also led to confusion. Participants did not generally overestimate their risk, but some were uncertain about whether they were taking the right preventive actions and/or whether their children were at risk. Information about genetic susceptibilities was difficult to make sense of, as it related to ambiguous risks for participants and family members, complicated and unfamiliar terminology and multiple genes and preventive strategies. Conclusion Policy visions of clinicians and patients in mainstream

  18. Classical against molecular-genetic methods for susceptibility testing of antituberculotics.

    PubMed

    Porvaznik, I; Mokry, J; Solovic, I

    2015-01-01

    Tuberculosis currently belongs to rare respiratory diseases in Slovakia. However, the emergence and spread of multi-drug resistant tuberculosis (MDR-TB) and extensively drug-resistant tuberculosis (XDR-TB) are major challenges for global tuberculosis control, since the treatment of resistant forms creates both medical and financial problems. Cultivation methods of diagnosis are time-consuming, many times exceeding the time of the initial phase of tuberculosis treatment. Therefore, in the presented study we compared the standard procedures, based on the cultivation of mycobacteria and subsequent drug susceptibility testing to antituberculotics, with molecular-genetic methods using PCR diagnostic kits. The molecular-genetic testing enables to obtain direct and fast evidence of Mycobacterium tuberculosis, with genomic verification of resistance to the most important anti-tuberculosis drugs - isoniazid and rifampicin in MDR-TB, and ethambutol, aminoglycosides, and fluoroquinolones in XDR-TB. In 2012-2013, we confirmed 19 cases of drug-resistant tuberculosis in Slovakia. The resistance to rifampicin was confirmed in all strains with both methods. In two cases, the molecular-genetic testing did not show resistance to isoniazid, as confirmed by conventional cultivation. Furthermore, two strains demonstrating susceptibility in conventional microbiological testing to ethambutol and five strains to fluoroquinolones were verified as actually being resistant using a PCR method. Rapid diagnosis and identification of MDR-TB or XDR-TB strains using molecular-genetic testing is an essential tool for the timely and appropriate drug treatment and prevention of spread of drug resistant strains.

  19. Performance of Vitek 2 for antimicrobial susceptibility testing of Staphylococcus spp. and Enterococcus spp.

    PubMed

    Bobenchik, April M; Hindler, Janet A; Giltner, Carmen L; Saeki, Sandra; Humphries, Romney M

    2014-02-01

    Vitek 2 (bioMérieux, Inc., Durham, NC) is a widely used commercial antimicrobial susceptibility testing system. We compared MIC results obtained by Vitek 2 to those obtained by the Clinical and Laboratory Standards Institute (CLSI) broth microdilution (BMD) reference method for 134 staphylococcal and 84 enterococcal clinical isolates. Nineteen agents were evaluated, including all those available on Vitek 2 for testing staphylococci and enterococci. The resistance phenotypes tested included methicillin-resistant Staphylococcus aureus (MRSA) (n = 58), S. aureus with inducible clindamycin resistance (ICR) (n = 30), trimethoprim-sulfamethoxazole-resistant MRSA (n = 10), vancomycin-resistant Enterococcus (n = 37), high-level gentamicin-resistant Enterococcus (n = 15), linezolid-resistant Enterococcus (n = 5), and daptomycin-nonsusceptible Enterococcus faecalis (n = 6). For the staphylococci, there was 98.9% categorical agreement (CA). There was one very major error (VME) for gentamicin in a Staphylococcus hominis isolate, six VMEs for inducible clindamycin in S. aureus isolates, and two major errors (ME) for daptomycin in an S. aureus and a Staphylococcus epidermidis isolate. For enterococci, there was 97.3% CA. Two VMEs were observed for daptomycin in isolates of E. faecalis and 2 ME, 1 for high-level gentamicin resistance and 1 for nitrofurantoin, in E. faecium isolates. Overall, there was 98.3% CA and 99% essential agreement for the testing of staphylococci and enterococci by the Vitek 2. With the exception of detecting ICR in S. aureus, Vitek 2 performed reliably for antimicrobial susceptibility testing of staphylococci and enterococci.

  20. A Rapid Molecular Test for Determining Yersinia pestis Susceptibility to Ciprofloxacin by the Quantification of Differentially Expressed Marker Genes

    PubMed Central

    Steinberger-Levy, Ida; Shifman, Ohad; Zvi, Anat; Ariel, Naomi; Beth-Din, Adi; Israeli, Ofir; Gur, David; Aftalion, Moshe; Maoz, Sharon; Ber, Raphael

    2016-01-01

    Standard antimicrobial susceptibility tests used to determine bacterial susceptibility to antibiotics are growth dependent and time consuming. The long incubation time required for standard tests may render susceptibility results irrelevant, particularly for patients infected with lethal bacteria that are slow growing on agar but progress rapidly in vivo, such as Yersinia pestis. Here, we present an alternative approach for the rapid determination of antimicrobial susceptibility, based on the quantification of the changes in the expression levels of specific marker genes following exposure to growth-inhibiting concentrations of the antibiotic, using Y. pestis and ciprofloxacin as a model. The marker genes were identified by transcriptomic DNA microarray analysis of the virulent Y. pestis Kimberley53 strain after exposure to specific concentrations of ciprofloxacin for various time periods. We identified several marker genes that were induced following exposure to growth-inhibitory concentrations of ciprofloxacin, and we confirmed the marker expression profiles at additional ciprofloxacin concentrations using quantitative RT-PCR. Eleven candidate marker transcripts were identified, of which four mRNA markers were selected for a rapid quantitative RT-PCR susceptibility test that correctly determined the Minimal Inhibitory Concentration (MIC) values and the categories of susceptibility of several Y. pestis strains and isolates harboring various ciprofloxacin MIC values. The novel molecular susceptibility test requires just 2 h of antibiotic exposure in a 7-h overall test time, in contrast to the 24 h of antibiotic exposure required for a standard microdilution test. PMID:27242774

  1. Reverberation Chamber Uniformity Validation and Radiated Susceptibility Test Procedures for the NASA High Intensity Radiated Fields Laboratory

    NASA Technical Reports Server (NTRS)

    Koppen, Sandra V.; Nguyen, Truong X.; Mielnik, John J.

    2010-01-01

    The NASA Langley Research Center's High Intensity Radiated Fields Laboratory has developed a capability based on the RTCA/DO-160F Section 20 guidelines for radiated electromagnetic susceptibility testing in reverberation chambers. Phase 1 of the test procedure utilizes mode-tuned stirrer techniques and E-field probe measurements to validate chamber uniformity, determines chamber loading effects, and defines a radiated susceptibility test process. The test procedure is segmented into numbered operations that are largely software controlled. This document is intended as a laboratory test reference and includes diagrams of test setups, equipment lists, as well as test results and analysis. Phase 2 of development is discussed.

  2. 3D Elastic Solutions for Laterally Loaded Discs: Generalised Brazilian and Point Load Tests

    NASA Astrophysics Data System (ADS)

    Serati, Mehdi; Alehossein, Habib; Williams, David J.

    2014-07-01

    This paper investigates the application of a double Fourier series technique to the construction of an elastic stress field in a cylindrical bar subject to lateral boundary loads. The lateral loads, including the constant load boundary conditions, are represented by two Fourier series: one on the perimeter of the circular section ( r 0, θ) and the other on the longitudinal curved surface parallel to the bar axis ( z). The technique invokes acceptable potential functions of the Papkovich-Neuber displacement field, satisfying the governing partial differential equations, to assign appropriate odd and even trigonometric Fourier terms in cylindrical coordinates ( r, θ, z). The generic solution decomposes the problem of interest to a state of stress caused by two independent boundary conditions along the z axis and θ-polar angle, both superimposed on a solution for which these potentials are the product of the trigonometric terms of the independent variables ( θ, z). Constants appearing in the resultant second-order partial differential equations are determined from the generally mixed (tractions and/or displacements) boundary conditions. While the solutions are satisfied exactly at the ends of an infinite bar, they are satisfied weakly on average, in the light of Saint Venant's approximation at the two ends of a finite bar. The application of the proposed analysis is verified against available elastic solutions for axisymmetric and non-axisymmetric engineering problems such as the indirect Brazilian Tensile Strength and Point Load Strength tests.

  3. Rapid inoculum standardization system: a novel device for standardization of inocula in antimicrobial susceptibility testing.

    PubMed Central

    Wicks, J H; Nelson, R L; Krejcarek, G E

    1983-01-01

    A rapid inoculum standardization system for antimicrobial susceptibility testing without incubation or the conventional turbidity adjustment has been developed. The rapid inoculum standardization system consists of a plastic rod with cross-hatched grooves on one end and a specific nutrient medium in a vial. The crosshatched grooves are designed to pick up and release a known number of viable microorganisms. In use, the end of the rod is touched to five colonies 1 to 2 mm in diameter from a primary agar plate, thus filling the grooves with bacteria. The rod is placed into the vial, and the bacteria are suspended in the medium by agitation with a Vortex Genie Mixer. The resulting suspension contains 5 X 10(7) to 5 X 10(8) CFU/ml for most gram-negative bacilli and gram-positive cocci. Microorganisms such as streptococci that have colonies less than 1 mm in diameter require as many as 10 colonies for an adequate inoculum suspension. Ninety-five commonly encountered bacterial isolates were tested in triplicate by agar plate counts. The resulting overall geometric mean of the agar plate counts was 1.52 X 10(8) CFU/ml for the species tested. We have found that the rapid inoculum standardization system provides a consistent and reproducible method for the standardization of inoculum for antimicrobial susceptibility testing without the incubation period and turbidity adjustment. Images PMID:6874902

  4. Direct Susceptibility Testing of Mycobacterium tuberculosis for Pyrazinamide by Use of the Bactec MGIT 960 System

    PubMed Central

    Demers, Anne-Marie; Venter, Amour; Friedrich, Sven O.; Rojas-Ponce, Gabriel; Mapamba, Daniel; Jugheli, Levan; Sasamalo, Mohammed; Almeida, Deepak; Dorasamy, Afton; Jentsch, Ute; Gibson, Mara; Everitt, Daniel; Diacon, Andreas H.

    2016-01-01

    Pyrazinamide (PZA) is a key antituberculosis drug, yet no rapid susceptibility test is commercially available. PZA drug susceptibility testing (DST) was performed directly on sputum samples from 327 patients and compared with the indirect method by using the Bactec MGIT 960 system in the context of patient screening for participation in a drug trial. Compared to standard indirect PZA DST, direct DST was successful in only 59% of cases, but results obtained were highly accurate and available faster. Agreement between the direct and indirect methods varied from 90 to 100% in each laboratory. The median times for obtaining PZA results from the time when the specimen was collected ranged from 11 to 16 days for the direct test and 18 to 95 days for the indirect test across laboratories. The direct method is accurate and reproducible across laboratories. It can be expected to accelerate results in >50% of cases, but it cannot replace indirect DST for PZA. Phenotypic methods remain the gold standard for DST in drug trials. If future studies can optimize the method to decrease the number of uninterpretable results, direct MGIT DST could be the new phenotypic DST standard for clinical trials, providing more rapid detection of resistance to new drugs in experimental regimens. PMID:26912751

  5. Direct Susceptibility Testing of Mycobacterium tuberculosis for Pyrazinamide by Use of the Bactec MGIT 960 System.

    PubMed

    Demers, Anne-Marie; Venter, Amour; Friedrich, Sven O; Rojas-Ponce, Gabriel; Mapamba, Daniel; Jugheli, Levan; Sasamalo, Mohammed; Almeida, Deepak; Dorasamy, Afton; Jentsch, Ute; Gibson, Mara; Everitt, Daniel; Eisenach, Kathleen D; Diacon, Andreas H

    2016-05-01

    Pyrazinamide (PZA) is a key antituberculosis drug, yet no rapid susceptibility test is commercially available. PZA drug susceptibility testing (DST) was performed directly on sputum samples from 327 patients and compared with the indirect method by using the Bactec MGIT 960 system in the context of patient screening for participation in a drug trial. Compared to standard indirect PZA DST, direct DST was successful in only 59% of cases, but results obtained were highly accurate and available faster. Agreement between the direct and indirect methods varied from 90 to 100% in each laboratory. The median times for obtaining PZA results from the time when the specimen was collected ranged from 11 to 16 days for the direct test and 18 to 95 days for the indirect test across laboratories. The direct method is accurate and reproducible across laboratories. It can be expected to accelerate results in >50% of cases, but it cannot replace indirect DST for PZA. Phenotypic methods remain the gold standard for DST in drug trials. If future studies can optimize the method to decrease the number of uninterpretable results, direct MGIT DST could be the new phenotypic DST standard for clinical trials, providing more rapid detection of resistance to new drugs in experimental regimens.

  6. Termite-Susceptible Species of Wood for Inclusion as a Reference in Indonesian Standardized Laboratory Testing.

    PubMed

    Arinana; Tsunoda, Kunio; Herliyana, Elis N; Hadi, Yusuf S

    2012-03-28

    Standardized laboratory testing of wood and wood-based products against subterranean termites in Indonesia (SNI 01.7207-2006) (SNI) has no requirement for the inclusion of a comparative reference species of wood (reference control). This is considered a weakness of the Indonesian standard. Consequently, a study was undertaken to identify a suitable Indonesian species of community wood that could be used as a reference control. Four candidate species of community woods: Acacia mangium, Hevea brasiliensis, Paraserianthes falcataria and Pinus merkusii were selected for testing their susceptibility to feeding by Coptotermes formosanus. Two testing methods (SNI and the Japanese standard method JIS K 1571-2004) were used to compare the susceptibility of each species of wood. Included in the study was Cryptomeria japonica, the reference control specified in the Japanese standard. The results of the study indicated that P. merkusii is a suitable reference species of wood for inclusion in laboratory tests against subterranean termites, conducted in accordance with the Indonesian standard (SNI 01.7207-2006).

  7. Evaluation of Carbon Nanotube Thin Films for Optically Transparent Microwave Applications Using On-Wafer Probing of Corbino Disc Test Structures

    DTIC Science & Technology

    2013-03-01

    Structures by Ryan C. Toonen , Julia B. Doggett, S. Gary Hirsch, Mathew P. Ivill, Eric H. Ngo, Clifford W. Hubbard, Henning Richter, and Ramesh Sivarajan...Corbino Disc Test Structures Ryan C. Toonen , S. Gary Hirsch, Mathew P. Ivill, Eric H. Ngo, and Clifford W. Hubbard Weapons and Materials Research...5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Ryan C. Toonen , Julia B. Doggett,* S. Gary Hirsch, Mathew P. Ivill, Eric H. Ngo, Clifford

  8. Antimicrobial susceptibility testing of Brachyspira intermedia and Brachyspira pilosicoli isolates from Australian chickens.

    PubMed

    Hampson, D J; Stephens, C P; Oxberry, S L

    2006-02-01

    Susceptibilities of predominantly Australian isolates of the pathogenic intestinal spirochaetes Brachyspira intermedia (n = 25) and Brachyspira pilosicoli (n = 17) from chickens were tested in agar dilution against four concentrations each of the antimicrobials tiamulin, lincomycin, tylosin, metronidazole, tetracycline and ampicillin. Based on available minimum inhibitory concentration (MIC) breakpoint values for Brachyspira hyodysenteriae or other Gram-negative enteric veterinary pathogens, isolates of both species generally were susceptible to tiamulin, lincomycin, metronidazole and tetracycline. Although not classed as resistant, four isolates of B. intermedia had an elevated MIC range for tiamulin (1 to 4 mg/l), 11 isolates of B. intermedia and five of B. pilosicoli had an elevated MIC range for lincomycin (10 to 50 mg/l), one isolate of B. pilosicoli had an elevated MIC range for tetracycline (10 to 20 mg/l), and one isolate of B. intermedia and five of B. pilosicoli had an elevated MIC range for ampicillin (10 to 50 mg/l). A clear lack of susceptibility to tylosin (MIC > 4 mg/l) was seen in 11 isolates each of B. intermedia and B. pilosicoli, and to ampicillin (MIC > 32 mg/l) in two isolates of B. pilosicoli. These data suggest that some resistance to common antimicrobials exists among intestinal spirochetes obtained from laying hens and supports the need of MIC data for clinical isolates before any treatment is considered.

  9. Rapid susceptibility testing of Mycobacterium tuberculosis by bioluminescence assay of mycobacterial ATP

    SciTech Connect

    Nilsson, L.E.; Hoffner, S.E.; Ansehn, S.

    1988-08-01

    Mycobacterial growth was monitored by bioluminescence assay of mycobacterial ATP. Cultures of Mycobacterium tuberculosis H37Rv and of 25 clinical isolates of the same species were exposed to serial dilutions of ethambutol, isoniazid, rifampin, and streptomycin. A suppression of ATP, indicating growth inhibition, occurred for susceptible but not resistant strains within 5 to 7 days of incubation. Breakpoint concentrations between susceptibility and resistance were determined by comparing these results with those obtained by reference techniques. Full agreement was found in 99% of the assays with the resistance ratio method on Lowenstein-Jensen medium, and 98% of the assays were in full agreement with the radiometric system (BACTEC). A main advantage of the bioluminescence method is its rapidity, with results available as fast as with the radiometric system but at a lower cost and without the need for radioactive culture medium. The method provides kinetic data concerning drug effects within available in vivo drug concentrations and has great potential for both rapid routine susceptibility testing and research applications in studies of drug effects on mycobacteria.

  10. Genetic antimicrobial susceptibility testing in Gram-negative sepsis - impact on time to results in a routine laboratory.

    PubMed

    Kommedal, Øyvind; Aasen, Johanne Lind; Lindemann, Paul Christoffer

    2016-07-01

    Diagnostic testing of positive blood cultures is among the most critical tasks performed by clinical microbiology laboratories, and the total analysis time from sampling to results should be kept as short as possible. By providing identification of pelleted bacteria directly from positive blood-cultures, MALDI-TOF MS opens for relatively low-complex species-adjusted genetic susceptibility testing from the same bacterial pellet. In our lab routine, we prospectively evaluated a rapid in-house real-time PCR targeting the most common aminoglycoside and cephalosporin resistance genes in Escherichia coli and Klebsiella pneumoniae and measured time to preliminary susceptibility reporting for 138 samples. The results were compared to direct phenotypic susceptibility testing with interpretation after 6 h and overnight incubation respectively. Results from the genetic susceptibility testing were available for 69.5% (96/138) of the positive blood cultures within 24 h after sample collection. No phenotypic susceptibility results were available at this time. Compared to overnight direct susceptibility testing, the average time from sample collection to preliminary susceptibility reporting was reduced with 43%, from 45 h and 5 min to 25 h and 44 min, providing an earlier adjustment of antimicrobial therapy for 12 patients. Minor logistic adjustments have the potential to save yet another 4 h.

  11. Preparation of ormetoprim-sulfadimethoxine-medicated discs for disc diffusion assay

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Romet ( a blend of ormetoprim and sulfadimethoxine) is a type A medicated article for the manufacture of medicated feed in the catfish industry. Recently, the commercial manufacture of ormetoprim-sulfadimethoxine susceptibility discs was discontinued. Ormetoprim-sulfadimethoxine discs were prepare...

  12. Risk perceptions, worry, and attitudes about genetic testing for breast cancer susceptibility.

    PubMed

    Cameron, Linda D; Reeve, Jeanne

    2006-01-01

    This study assessed the unique associations of risk perceptions and worry with attitudes about genetic testing for breast cancer susceptibility. Women (general practitioner clinic attenders, university students, and first-degree relatives of breast cancer survivors; N = 303) read information about genetic testing and completed measures assessing perceived cancer risk, cancer worry, and genetic testing attitudes and beliefs. Worry was associated with greater interest in genetic testing, stronger beliefs that testing has detrimental emotional consequences, and positive beliefs about benefits of testing and risk-reducing surgeries. Perceived risk was unrelated to interest and associated with more skeptical beliefs about emotional consequences and benefits of testing and risk-reducing surgeries. At low worry levels, testing interest increased with more positive beliefs about testing benefits; at high worry levels, interest was high regardless of benefits beliefs. The findings support Leventhal's Common-Sense Model of self-regulation delineating interactive influences of risk-related cognitions and emotions on information processing and behavior.

  13. CLSI performance standards for antimicrobial susceptibility testing of bacteria isoloated from aquatic animals; second information supplement. CLSI document VET03/VET04-S2

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The supplemental information presented in this document is intended for use with the antimicrobial susceptibility testing procedures published in the following Clinical and Laboratory Standards Institute (CLSI) approved documents VET03-A Methods for Antimicrobial Disk Susceptibility Testing of Bacte...

  14. Rapid Real-Time Antimicrobial Susceptibility Testing with Electrical Sensing on Plastic Microchips with Printed Electrodes.

    PubMed

    Safavieh, Mohammadali; Pandya, Hardik J; Venkataraman, Maanasa; Thirumalaraju, Prudhvi; Kanakasabapathy, Manoj Kumar; Singh, Anupriya; Prabhakar, Devbalaji; Chug, Manjyot Kaur; Shafiee, Hadi

    2017-03-30

    Rapid antimicrobial susceptibility testing is important for efficient and timely therapeutic decision making. Due to globally spread bacterial resistance, the efficacy of antibiotics is increasingly being impeded. Conventional antibiotic tests rely on bacterial culture, which is time-consuming and can lead to potentially inappropriate antibiotic prescription and up-front broad range of antibiotic use. There is an urgent need to develop point-of-care platform technologies to rapidly detect pathogens, identify the right antibiotics, and monitor mutations to help adjust therapy. Here, we report a biosensor for rapid (<90 min), real time, and label-free bacteria isolation from whole blood and antibiotic susceptibility testing. Target bacteria are captured on flexible plastic-based microchips with printed electrodes using antibodies (30 min), and its electrical response is monitored in the presence and absence of antibiotics over an hour of incubation time. We evaluated the microchip with Escherichia coli and methicillin-resistant Staphylococcus aureus (MRSA) as clinical models with ampicillin, ciprofloxacin, erythromycin, daptomycin, gentamicin, and methicillin antibiotics. The results are compared with the current standard methods, i.e. bacteria viability and conventional antibiogram assays. The technology presented here has the potential to provide precise and rapid bacteria screening and guidance in clinical therapies by identifying the correct antibiotics for pathogens.

  15. Antimicrobial susceptibility testing for Helicobacter pylori in times of increasing antibiotic resistance.

    PubMed

    Smith, Sinéad M; O'Morain, Colm; McNamara, Deirdre

    2014-08-07

    The gram-negative bacterium Helicobacter pylori (H. pylori) causes chronic gastritis, gastric and duodenal ulcers, gastric cancer and mucosa-associated lymphoid tissue lymphoma. Treatment is recommended in all symptomatic patients. The current treatment options for H. pylori infection are outlined in this review in light of the recent challenges in eradication success, largely due to the rapid emergence of antibiotic resistant strains of H. pylori. Antibiotic resistance is a constantly evolving process and numerous studies have shown that the prevalence of H. pylori antibiotic resistance varies significantly from country to country, and even between regions within the same country. In addition, recent data has shown that previous antibiotic use is associated with harbouring antibiotic resistant H. pylori. Local surveillance of antibiotic resistance is warranted to guide clinicians in their choice of therapy. Antimicrobial resistance is assessed by H. pylori culture and antimicrobial susceptibility testing. Recently developed molecular tests offer an attractive alternative to culture and allow for the rapid molecular genetic identification of H. pylori and resistance-associated mutations directly from biopsy samples or bacterial culture material. Accumulating evidence indicates that surveillance of antimicrobial resistance by susceptibility testing is feasible and necessary to inform clinicians in their choice of therapy for management of H. pylori infection.

  16. Radiometric method for testing susceptibility of mycobacteria to pyrazinamide in 7H12 broth.

    PubMed Central

    Heifets, L B; Iseman, M D

    1985-01-01

    The test of susceptibility to pyrazinamide requires an acid environment (pH less than or equal to 5.5). This, however, is not favorable to the growth of Mycobacterium tuberculosis, especially in solid agar media. To obviate this difficulty, we developed a testing method with 7H12 broth medium and based on radiometric readings of the growth. The radiometric method employed in this study (BACTEC system) provides an opportunity to detect the dynamics of growth by daily recording of the growth index, which reflects the metabolic activity of the multiplying bacteria. In our technique, M. tuberculosis isolates were initially cultivated at pH 6.8. After logarithmic growth had begun, phosphoric acid solution was added to obtain pH 5.5. When pyrazinamide was added simultaneously with the acid, the growth index of susceptible cultures decreased, whereas it continued to increase in pH 5.5 control vials and in tests with pyrazinamide-resistant strains. PMID:3972987

  17. Evaluating Constraints on Heavy-Ion SEE Susceptibility Imposed by Proton SEE Testing and Other Mixed Environments

    NASA Technical Reports Server (NTRS)

    Ladbury, R. L.; Lauenstein, J.-M.

    2016-01-01

    We develop metrics for assessing the effectiveness of proton SEE data for bounding heavy-ion SEE susceptibility. The metrics range from simple geometric criteria requiring no knowledge of the test articles to bounds of SEE rates.

  18. Correlation between bactericidal activity of fosfomycin trometamol in an in vitro model of the urinary bladder and susceptibility testing.

    PubMed

    Pinasi, C; Albini, E; Marca, G

    1987-01-01

    The present study was undertaken to define an interpretative guideline for disk diffusion susceptibility testing with fosfomycin trometamol, a new antimicrobial agent which has been developed for the treatment of urinary tract infections. Two potencies of fosfomycin disk were used: 50 and 200 micrograms, prepared in the presence and absence of glucose-6-phosphate. To verify the reliability of the results obtained in susceptibility testing, we have also evaluated the bactericidal activity of fosfomycin trometamol versus sensitive and resistant strains in an 'in vitro' model simulating the hydrokinetic aspects involved in the treatment of bacterial cystitis. The data obtained evidenced the role of glucose-6-phosphate in antimicrobial susceptibility tests as well as the importance of the urinary antibiotic concentrations to define sensitive and resistant bacteria. On the basis of our results, we recommend that a 200-microgram disk of fosfomycin containing 50 micrograms of glucose-6-phosphate should be used in antimicrobial susceptibility testing with fosfomycin trometamol.

  19. Methods for broth dilution susceptibility testing of bacteria isolated from aquatic animals; approved guideline-second edition

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Antimicrobial susceptibility testing is recommended to determine which antimicrobial agents should be considered for treating a bacterial pathogen. Many bacteria that cause disease in aquatic animals require growth conditions that vary substantially from routine terrestrial pathogens. It has thus ...

  20. Sizes of protoplanetary discs after star-disc encounters

    NASA Astrophysics Data System (ADS)

    Breslau, Andreas; Steinhausen, Manuel; Vincke, Kirsten; Pfalzner, Susanne

    2014-05-01

    Most stars do not form in isolation, but as part of a star cluster or association. These young stars are initially surrounded by protoplanetary discs. In these cluster environments tidal interactions with other cluster members can alter the disc properties. Besides the disc frequency, its mass, angular momentum, and energy, the disc's size is particularly prone to being changed by a passing star. So far the change in disc size has only been investigated for a small number of very specific encounters. Several studies investigated the effect of the cluster environment on the sizes of planetary systems like our own solar system, based on a generalisation of information from this limited sample. We performed numerical simulations covering the wide parameter space typical of young star clusters, to test the validity of this approach. Here the sizes of discs after encounters are presented, based on a size definition that is comparable to the one used in observational studies. We find that, except for encounters between equal-mass stars, the usually applied estimates are insufficient. They tend to severely overestimate the remaining disc size. We show that the disc size after an encounter can be described by a relatively simple dependence on the periastron distance and the mass ratio of the encounter partners. This knowledge allows us, for example, to pin down the types of encounter possibly responsible for the structure of today's solar system. Appendix A is available in electronic form at http://www.aanda.org

  1. A novel microbead-based microfluidic device for rapid bacterial identification and antibiotic susceptibility testing.

    PubMed

    He, J; Mu, X; Guo, Z; Hao, H; Zhang, C; Zhao, Z; Wang, Q

    2014-12-01

    Effective treatment of infectious diseases depends on the ability to rapidly identify the infecting bacteria and the use of sensitive antibiotics. The currently used identification assays usually take more than 72 h to perform and have a low sensitivity. Herein, we present a microbead-based microfluidic platform that is highly sensitive and rapid for bacterial detection and antibiotic sensitivity testing. The platform includes four units, one of which is used for bacterial identification and the other three are used for susceptibility testing. Our results showed that Escherichia coli O157 at a cell density range of 10(1)-10(5) CFU/μL could be detected within 30 min. Additionally, the effects of three antibiotics on E. coli O157 were evaluated within 4-8 h. Overall, this integrated microbead-based microdevice provides a sensitive, rapid, reliable, and highly effective platform for the identification of bacteria, as well as antibiotic sensitivity testing.

  2. Determination of disk diffusion susceptibility testing interpretive criteria using model-based analysis: development and implementation.

    PubMed

    DePalma, Glen; Turnidge, John; Craig, Bruce A

    2017-02-01

    The determination of diffusion test breakpoints has become a challenging issue due to the increasing resistance of microorganisms to antibiotics. Currently, the most commonly-used method for determining these breakpoints is the modified error-rate bounded method. Its use has remained widespread despite the introduction of several model-based methods that have been shown superior in terms of precision and accuracy. However, the computational complexities associated with these new approaches has been a significant barrier for clinicians. To remedy this, we developed and examine the utility of a free online software package designed for the determination of diffusion test breakpoints: dBETS (diffusion Breakpoint Estimation Testing Software). This software package allows clinicians to easily analyze data from susceptibility experiments through visualization, error-rate bounded, and model-based approaches. We analyze four publicly available data sets from the Clinical and Laboratory Standards Institute using dBETS.

  3. Physically-based landslide susceptibility modelling: geotechnical testing and model evaluation issues

    NASA Astrophysics Data System (ADS)

    Marchesini, Ivan; Mergili, Martin; Schneider-Muntau, Barbara; Alvioli, Massimiliano; Rossi, Mauro; Guzzetti, Fausto

    2015-04-01

    We used the software r.slope.stability for physically-based landslide susceptibility modelling in the 90 km² Collazzone area, Central Italy, exploiting a comprehensive set of lithological, geotechnical, and landslide inventory data. The model results were evaluated against the inventory. r.slope.stability is a GIS-supported tool for modelling shallow and deep-seated slope stability and slope failure probability at comparatively broad scales. Developed as a raster module of the GRASS GIS software, r.slope.stability evaluates the slope stability for a large number of randomly selected ellipsoidal potential sliding surfaces. The bottom of the soil (for shallow slope stability) or the bedding planes of lithological layers (for deep-seated slope stability) are taken as potential sliding surfaces by truncating the ellipsoids, allowing for the analysis of relatively complex geological structures. To take account for the uncertain geotechnical and geometric parameters, r.slope.stability computes the slope failure probability by testing multiple parameter combinations sampled deterministically or stochastically, and evaluating the ratio between the number of parameter combinations yielding a factor of safety below 1 and the total number of tested combinations. Any single raster cell may be intersected by multiple sliding surfaces, each associated with a slope failure probability. The most critical sliding surface is relevant for each pixel. Intensive use of r.slope.stability in the Collazzone Area has opened up two questions elaborated in the present work: (i) To what extent does a larger number of geotechnical tests help to better constrain the geotechnical characteristics of the study area and, consequently, to improve the model results? The ranges of values of cohesion and angle of internal friction obtained through 13 direct shear tests corresponds remarkably well to the range of values suggested by a geotechnical textbook. We elaborate how far an increased number of

  4. Single-disk diffusion testing (Kirby-Bauer) of susceptibility of Proteus mirabilis to chloramphenicol: significance of the intermediate category.

    PubMed

    Furtado, G L; Medeiros, A A

    1980-10-01

    The significance of the intermediate category of the single-disk diffusion test (Kirby-Bauer) of antibiotic susceptibility has never been clearly defined. Thirty-two percent of 756 clinical isolates of Proteus mirabilis were of intermediate susceptibility to chloramphenicol, a higher percentage than for any other species. The breakpoint separating susceptible and intermediate isolates nearly bisected the frequency distribution of zone diameters of P. mirabilis but not that of the other species. The breakpoint separating susceptible and intermediate isolates nearly bisected the frequency distribution of zone diameters of P. mirabillis but not that of the other species tested. By serial broth dilution testing, the minimal inhibitory concentrations (MICs) of chloramphenicol of 50 individual isolates of P. mirabilis were 3.9 to 22.1 micrograms/ml (geometric mean, 8.0), whereas the MICs of susceptible Escherichia coli, Klebsiella, and Enterobacter strains were 2.0 to 3.9 micrograms/ml (geometric mean, 2.9). Seventy percent of isolates of P. mirabilis with MICs of 7.8 to 15.6 micrograms/ml were classified as susceptible by disk testing. We conclude that existing Kirby-Bauer breakpoints do not accurately discriminate P. mirabilis isolates that are marginally susceptible to chloramphenicol. These data underscore the difficulty of applying a single set of breakpoints to all species and suggest that species-specific breakpoints would more accurately predict the MIC equivalent of given zone diameters.

  5. Psychological impact of genetic testing for cancer susceptibility: an update of the literature.

    PubMed

    Meiser, Bettina

    2005-12-01

    This article presents an overview of the rapidly evolving body of literature on the psychological impact of genetic testing for hereditary breast/ovarian cancer susceptibility, hereditary non-polyposis colorectal cancer (HNPCC) and familial adenomatous polyposis (FAP). Uptake of genetic testing for BRCA1/2 and HNPCC-related mutations is more consistently related to psychological factors, rather than sociodemographic variables. Most studies on the psychological impact of genetic testing amongst individuals who have never been affected by cancer demonstrate that non-carriers derive significant psychological benefits from genetic testing, while no adverse effects have been observed amongst carriers. These benefits are more clear-cut for HNPCC, compared to hereditary breast/ovarian cancer, reflecting differences in risk management options. The few studies available on individuals affected with cancer indicate that the impact of genetic testing is mediated and amplified by their former experience of cancer. Future directions and challenges of research in this area are reviewed. In particular, more empirical data are needed on the broader impact of genetic testing on those with inconclusive results or results of uncertain significance. As genetic testing is becoming available for other types of familial cancer, additional investigations will be needed as there is evidence to suggest that the impact of genetic testing may be unique to each type of familial cancer.

  6. Detection of relatively penicillin G-resistant Neisseria meningitidis by disk susceptibility testing.

    PubMed Central

    Campos, J; Mendelman, P M; Sako, M U; Chaffin, D O; Smith, A L; Sáez-Nieto, J A

    1987-01-01

    Beginning in 1985, relatively penicillin G-resistant (Penr) meningococci which did not produce beta-lactamase were isolated from the blood and cerebrospinal fluid of patients in Spain. We identified 16 Penr (mean MIC, 0.3 microgram/ml; range, 0.1 to 0.7 microgram/ml) and 12 penicillin-susceptible (Pens; mean MIC, less than or equal to 0.06 microgram/ml) strains of Neisseria meningitidis by the agar dilution technique using an inoculum of 10(4) CFU and questioned which disk susceptibility test would best differentiate these two populations. We compared the disk susceptibility of these strains using disks containing 2 (P2) and 10 (P10) U of penicillin G, 2 (Am2) and 10 (Am10) micrograms of ampicillin, and 1 microgram of oxacillin (OX1). We also investigated susceptibility with disks containing 30 micrograms of each of cephalothin (CF30), cefoxitin (FOX30), cefuroxime (CXM30), and cefotaxime (CTX30) and 75 micrograms of cefoperazone (CFP75) and determined by cluster analysis any correlation with the zone diameters obtained with P2 disks. Using the P2 and AM2 disks (in contrast to the P10 and AM10 disks), we correctly differentiated all the Penr from Pens isolates. In addition, the zone diameters with the P2 disk gave the best correlation with the penicillin G MIC determinations. All 16 Penr strains and 3 of 12 Pens strains showed zone diameters of 6 mm around OX1 disks, limiting the usefulness of OX1 disks. The zone diameters obtained with CF30, CXM30, and OX1 disks correlated with those obtained with the P2 disk, which suggests that these antibiotics have similar effects on these strains. In contrast, the data obtained with FOX30, CTX30, and CFP75 disks did not cluster with those obtained with the P2 disk, which suggests that there was a difference in the bacterial target or reflects their greater activity. We conclude that the P2 disk tests more readily identify Penr meningococci than do the standard P10 disk tests. PMID:3124729

  7. ESBL Detection: Comparison of a Commercially Available Chromogenic Test for Third Generation Cephalosporine Resistance and Automated Susceptibility Testing in Enterobactericeae

    PubMed Central

    El-Jade, Mohamed Ramadan; Parcina, Marijo; Schmithausen, Ricarda Maria; Stein, Christoph; Meilaender, Alina; Hoerauf, Achim; Molitor, Ernst

    2016-01-01

    Rapid detection and reporting of third generation cephalosporine resistance (3GC-R) and of extended spectrum betalactamases in Enterobacteriaceae (ESBL-E) is a diagnostic and therapeutic priority to avoid inefficacy of the initial antibiotic regimen. In this study we evaluated a commercially available chromogenic screen for 3GC-R as a predictive and/or confirmatory test for ESBL and AmpC activity in clinical and veterinary Enterobacteriaceae isolates. The test was highly reliable in the prediction of cefotaxime and cefpodoxime resistance, but there was no correlation with ceftazidime and piperacillin/tazobactam minimal inhibitory concentrations. All human and porcine ESBL-E tested were detected with exception of one genetically positive but phenotypically negative isolate. By contrast, AmpC detection rates lay below 30%. Notably, exclusion of piperacillin/tazobactam resistant, 3GC susceptible K1+ Klebsiella isolates increased the sensitivity and specificity of the test for ESBL detection. Our data further imply that in regions with low prevalence of AmpC and K1 positive E. coli strains chromogenic testing for 3GC-R can substitute for more time consuming ESBL confirmative testing in E. coli isolates tested positive by Phoenix or VITEK2 ESBL screen. We, therefore, suggest a diagnostic algorithm that distinguishes 3GC-R screening from primary culture and species-dependent confirmatory ESBL testing by βLACTATM and discuss the implications of MIC distribution results on the choice of antibiotic regimen. PMID:27494134

  8. ESBL Detection: Comparison of a Commercially Available Chromogenic Test for Third Generation Cephalosporine Resistance and Automated Susceptibility Testing in Enterobactericeae.

    PubMed

    El-Jade, Mohamed Ramadan; Parcina, Marijo; Schmithausen, Ricarda Maria; Stein, Christoph; Meilaender, Alina; Hoerauf, Achim; Molitor, Ernst; Bekeredjian-Ding, Isabelle

    2016-01-01

    Rapid detection and reporting of third generation cephalosporine resistance (3GC-R) and of extended spectrum betalactamases in Enterobacteriaceae (ESBL-E) is a diagnostic and therapeutic priority to avoid inefficacy of the initial antibiotic regimen. In this study we evaluated a commercially available chromogenic screen for 3GC-R as a predictive and/or confirmatory test for ESBL and AmpC activity in clinical and veterinary Enterobacteriaceae isolates. The test was highly reliable in the prediction of cefotaxime and cefpodoxime resistance, but there was no correlation with ceftazidime and piperacillin/tazobactam minimal inhibitory concentrations. All human and porcine ESBL-E tested were detected with exception of one genetically positive but phenotypically negative isolate. By contrast, AmpC detection rates lay below 30%. Notably, exclusion of piperacillin/tazobactam resistant, 3GC susceptible K1+ Klebsiella isolates increased the sensitivity and specificity of the test for ESBL detection. Our data further imply that in regions with low prevalence of AmpC and K1 positive E. coli strains chromogenic testing for 3GC-R can substitute for more time consuming ESBL confirmative testing in E. coli isolates tested positive by Phoenix or VITEK2 ESBL screen. We, therefore, suggest a diagnostic algorithm that distinguishes 3GC-R screening from primary culture and species-dependent confirmatory ESBL testing by βLACTATM and discuss the implications of MIC distribution results on the choice of antibiotic regimen.

  9. Development of an antimicrobial susceptibility testing method suitable for performance during space flight.

    PubMed Central

    Jorgensen, J H; Skweres, J A; Mishra, S K; McElmeel, M L; Maher, L A; Mulder, R; Lancaster, M V; Pierson, D L

    1997-01-01

    Very little is known regarding the effects of the microgravity environment of space flight upon the action of antimicrobial agents on bacterial pathogens. This study was undertaken to develop a simple method for conducting antibacterial susceptibility tests during a space shuttle mission. Specially prepared susceptibility test research cards (bioMérieux Vitek, Hazelwood, Mo.) were designed to include 6 to 11 serial twofold dilutions of 14 antimicrobial agents, including penicillins, cephalosporins, a beta-lactamase inhibitor, vancomycin, erythromycin, tetracycline, gentamicin, ciprofloxacin, and trimethoprim-sulfamethoxazole. MICs of the drugs were determined by visual reading of color end points in the Vitek research cards made possible by incorporation of a colorimetric growth indicator (alamarBlue; Accumed International, Westlake, Ohio). This study has demonstrated reproducible susceptibility results in the testing of isolates of Staphylococcus aureus, group A Streptococcus species, Enterococcus faecalis, Escherichia coli (beta-lactamase-positive and -negative strains), Klebsiella pneumoniae, Enterobacter cloacae, and Pseudomonas aeruginosa. In some instances, the MICs were comparable to those determined by a standard broth microdilution method, while in some cases the unique test media and format yielded slightly different values that were themselves reproducible. The proposed in-flight experiment will include inoculation of the Vitek cards on the ground prior to launch of the space shuttle, storage of inoculated cards at refrigeration temperature aboard the space shuttle until experiment initiation, and then incubation of the cards for 18 to 48 h prior to visual interpretation of MICs by the mission's astronauts. Ground-based studies have shown reproducible MICs following storage of inoculated cards for 7 days at 4 to 8 degrees C to accommodate the mission's time schedule and the astronaut's activities. For comparison, ground-based control (normal gravity

  10. Development of an Antimicrobial Susceptibility Testing Method Suitable for Performing During Space Flight

    NASA Technical Reports Server (NTRS)

    Jorgensen, James H.; Skweres, Joyce A.; Mishra S. K.; McElmeel, M. Letticia; Maher, Louise A.; Mulder, Ross; Lancaster, Michael V.; Pierson, Duane L.

    1997-01-01

    Very little is known regarding the affects of the microgravity environment of space flight upon the action of antimicrobial agents on bacterial pathogens. This study was undertaken to develop a simple method for conducting antibacterial susceptibility tests during a Space Shuttle mission. Specially prepared susceptibility test research cards (bioMerieux Vitek, Hazelwood, MO) were designed to include 6-11 serial two-fold dilutions of 14 antimicrobial agents, including penicillins, cephalosporins, a Beta-lactamase inhibitor, vancomycin, erythromycin, tetracycline, gentamicin, ciprofloxacin, and trimethoprim/sulfamethoxazole. Minimal inhibitory concentrations (MICS) of the drugs were determined by visual reading of color endpoints in the Vitek research cards made possible by incorporation of a colorimetric growth indicator (alamarBlue(Trademark), Accumed International, Westlake, OH). This study has demonstrated reproducible susceptibility results when testing isolates of Staphylococcus aurezis, Group A Streptococcus, Enterococcusfaecalis, Escherichia coli (beta-lactamase positive and negative strains), Klebsiella pneumoniae, Enterobacter cloacae, and Pseudomoiias aeruginosa. In some instances, the MICs were comparable to those determined using a standard broth microdilution method, while in some cases the unique test media and format yielded slightly different values, that were themselves reproducible. The proposed in-flight experiment will include inoculation of the Vitek cards on the ground prior to launch of the Space Shuttle, storage of inoculated cards at refrigeration temperature aboard the Space Shuttle until experiment initiation, then incubation of the cards for 18-48 h prior to visual interpretation of MICs by the mission's astronauts. Ground-based studies have shown reproducible MICs following storage of inoculated cards for 7 days at 4-8 C to accommodate the mission's time schedule and the astronauts' activities. For comparison, ground-based control

  11. Cancer therapy. Ex vivo culture of circulating breast tumor cells for individualized testing of drug susceptibility.

    PubMed

    Yu, Min; Bardia, Aditya; Aceto, Nicola; Bersani, Francesca; Madden, Marissa W; Donaldson, Maria C; Desai, Rushil; Zhu, Huili; Comaills, Valentine; Zheng, Zongli; Wittner, Ben S; Stojanov, Petar; Brachtel, Elena; Sgroi, Dennis; Kapur, Ravi; Shioda, Toshihiro; Ting, David T; Ramaswamy, Sridhar; Getz, Gad; Iafrate, A John; Benes, Cyril; Toner, Mehmet; Maheswaran, Shyamala; Haber, Daniel A

    2014-07-11

    Circulating tumor cells (CTCs) are present at low concentrations in the peripheral blood of patients with solid tumors. It has been proposed that the isolation, ex vivo culture, and characterization of CTCs may provide an opportunity to noninvasively monitor the changing patterns of drug susceptibility in individual patients as their tumors acquire new mutations. In a proof-of-concept study, we established CTC cultures from six patients with estrogen receptor-positive breast cancer. Three of five CTC lines tested were tumorigenic in mice. Genome sequencing of the CTC lines revealed preexisting mutations in the PIK3CA gene and newly acquired mutations in the estrogen receptor gene (ESR1), PIK3CA gene, and fibroblast growth factor receptor gene (FGFR2), among others. Drug sensitivity testing of CTC lines with multiple mutations revealed potential new therapeutic targets. With optimization of CTC culture conditions, this strategy may help identify the best therapies for individual cancer patients over the course of their disease.

  12. An in situ antimicrobial susceptibility testing method based on in vivo measurements of chlorophyll α fluorescence.

    PubMed

    Heliopoulos, Nikolaos S; Galeou, Angeliki; Papageorgiou, Sergios K; Favvas, Evangelos P; Katsaros, Fotios K; Stamatakis, Kostas

    2015-05-01

    Up to now antimicrobial susceptibility testing (AST) methods are indirect and generally involve the manual counting of bacterial colonies following the extraction of microorganisms from the surface under study and their inoculation in a separate procedure. In this work, an in situ, direct and instrumental method for the evaluation and assessment of antibacterial properties of materials and surfaces is proposed. Instead of indirectly determining antibacterial activity using the typical gram(-) test organisms with the subsequent manual colony count or inhibition zone measurement, the proposed procedure, employs photosynthetic gram(-) cyanobacteria deposited directly onto the surface under study and assesses cell proliferation and viability by a quick, accurate and reproducible instrumental chlorophyll fluorescence spectrophotometric technique. In contrast with existing methods of determination of antibacterial properties, it produces high resolution and quantitative results and is so versatile that it could be used to evaluate the antibacterial properties of any compound (organic, inorganic, natural or man-made) under any experimental conditions, depending on the targeted application.

  13. Direct disk diffusion susceptibility testing from respiratory tract specimens: focus on Pseudomonas aeruginosa.

    PubMed

    Perez, Leandro Reus Rodrigues; Freitas, Ana Lúcia Peixoto de; Barth, Afonso Luís; Dias, Cícero Armídio Gomes

    2014-09-01

    The aim of this study was to evaluate the application of direct disk diffusion (DDD) testing to respiratory tract specimens for the prediction of the antimicrobial susceptibility profile. DDD was performed on 144 specimens containing P. aeruginosa and the disk diffusion test was used as reference method. Agreement with the reference method was 77.8% for amikacin, 69.4% for cefepime, 86.1% for levofloxacin, 87.5% for meropenem, and 62.5% for piperacillin/tazobactam. Very major errors were observed for all agents, except levofloxacin. Our study showed that DDD results are inaccurate and may lead to errors in early decision-making regarding antibiotic therapy for lower respiratory tract infections.

  14. 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

  15. 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

  16. Cephalothin is not a reliable surrogate marker for oral cephalosporins in susceptibility testing of Enterobacteriaceae causing urinary tract infection.

    PubMed

    López, Itziar Angulo; Montes, Jorge Calvo; Álvarez, Mar Justel; Mazarrasa, Carlos Fernández; Martínez-Martínez, Luis

    2016-12-01

    Vitek® 2 (bioMérieux) is a widely used commercial antimicrobial susceptibility test (AST) system. AST-N244 card includes cephalothin as first-generation cephalosporin. We compared the cephalothin susceptibility results obtained with Vitek® 2 AST-N244 to those obtained by broth microdilution (BMD) and disk diffusion (DD) for 212 urinary Enterobacteriaceae. We also evaluated the differences between cefazolin and cephalothin susceptibility results. The overall performance of Vitek® 2 for cephalothin testing was 74.5% and 76.4% category agreement compared to BMD and DD, respectively; 84.4% essential agreement; very major errors 15.2% and 11.1% compared to BMD and DD; major errors 0% compared to both methods; and minor errors 22.2% and 21.7% compared to BMD and DD. Regarding correlation between cephalothin and cefazolin, the differences observed were statistically significant (P<0.0001) for the 167 Escherichia coli included (39.5% cephalothin susceptible versus 92.2% cefazolin susceptible by BMD; 41.9% cephalothin susceptible versus 93.4% cefazolin susceptible by DD). Vitek® 2 should provide cefazolin instead of cephalothin as a surrogate marker for oral cephalosporins on the urinary AST-244 cards in order to follow the CLSI (2016) recommendations.

  17. Genetic diversity and antifungal susceptibility testing of Trichosporon asahii isolated of Intensive Care Units patients

    PubMed Central

    de Oliveira Silva, Rosana Bellan; Fusco-Almeida, Ana Marisa; Matsumoto, Marcelo Teruyuki; Baeza, Lilian Cristiane; Benaducci, Tatiane; Mendes-Giannini, Maria José Soares

    2008-01-01

    Trichosporon asahii is an opportunistic pathogen, associated with a high mortality rate in immunocompromised patients. In this study, ten isolates, recovered from oral cavity and urine of patients in Intensive Care Units (ICU) over six months, were identified by classical and molecular methods, typed by RAPD and tested in vitro for susceptibility to fluconazole, itraconazole, 5-flucytosine and amphotericin B. A total agreement between the identification of Trichosporon sp by PCR based on sequences of the Internal Transcribed Spacer Regions (ITS) and on the sequences of small-subunit (SSU) ribosomal DNA (rDNA) was found. Randomly amplified of polymorphic DNA (RAPD), with primers P6 and M13, was used to determine the genomic profiles. The dendogram analysis indicated that almost all strains showed similarity >0.9 among them and all strains were multidrug-resistant. This study brings new results on the identification and genotyping of T. asahii isolated from Brazilian ICU patients and information about their antifungal drugs susceptibility. PMID:24031270

  18. The power of DNA double-strand break (DSB) repair testing to predict breast cancer susceptibility.

    PubMed

    Keimling, Marlen; Deniz, Miriam; Varga, Dominic; Stahl, Andreea; Schrezenmeier, Hubert; Kreienberg, Rolf; Hoffmann, Isabell; König, Jochem; Wiesmüller, Lisa

    2012-05-01

    Most presently known breast cancer susceptibility genes have been linked to DSB repair. To identify novel markers that may serve as indicators for breast cancer risk, we performed DSB repair analyses using a case-control design. Thus, we examined 35 women with defined familial history of breast and/or ovarian cancer (first case group), 175 patients with breast cancer (second case group), and 245 healthy women without previous cancer or family history of breast cancer (control group). We analyzed DSB repair in peripheral blood lymphocytes (PBLs) by a GFP-based test system using 3 pathway-specific substrates. We found increases of microhomology-mediated nonhomologous end joining (mmNHEJ) and nonconservative single-strand annealing (SSA) in women with familial risk vs. controls (P=0.0001-0.0022) and patients with breast cancer vs. controls (P=0.0004-0.0042). Young age (<50) at initial diagnosis of breast cancer, which could be indicative of genetic predisposition, was associated with elevated SSA using two different substrates, amounting to similar odds ratios (ORs=2.54-4.46, P=0.0059-0.0095) as for familial risk (ORs=2.61-4.05, P=0.0007-0.0045). These findings and supporting validation data underscore the great potential of detecting distinct DSB repair activities in PBLs as method to estimate breast cancer susceptibility beyond limitations of genotyping and to predict responsiveness to therapeutics targeting DSB repair-dysfunctional tumors.

  19. Antimicrobial potentials of Mentha longifolia by disc diffusion method.

    PubMed

    Bakht, Jehan; Shaheen, Salma; Shafi, Mohammad

    2014-07-01

    This study was conducted for the assessment of the antimicrobial activities of different solvents extracted samples from the aerial parts of Mentha longifolia against ten microbial species through the disc diffusion assay using two different concentrations of 1 and 2 mg disc1. All extracts from Mentha longifolia showed different ranges of antimicrobial activities. Butanol and ethyl acetate fractions showed inhibitory activities against all microbial species. Methanol fraction showed inhibitory effects against all the tested microbial species except Salmonella typhi. Salmonella typhi was also not controlled by methanol, petroleum ether and dichloromethane extracted samples. The most susceptible gram positive bacteria was Bacillus atropheus and Bacillus subtilis and were inhibited by all extracts and Staphylococus aureus was least susceptible among gram positive bacteria. Klebsiella pneumoniae was the most susceptible gram negative bacterium and Salmonella typhi was highly resistant among the gram negative bacteria. Erwinia carotovora and Agrobacterium tumefaciene were susceptible to all fractions. All fractions showed antifungal activities against Candida albicans except water extracted samples.

  20. Antibacterial susceptibility of bovine-mastitis pathogens tested directly in milk from infected quarters.

    PubMed

    Louhi-Lehtiö, M; Sandholm, M; Myllys, V; Honkanen-Buzalski, T

    1994-04-01

    Antibacterial susceptibilities of bovine-mastitis pathogens were analysed directly in 57 mastitic milk samples without inoculation with exogenous organisms. Aseptically collected milk was mixed with serial dilutions of antibacterials and the growth was observed using 2,3,5-triphenyltetrazolium chloride (TTC) reduction the following day. The results were compared with those obtained by using calibrated bacterial inocula in turbidimetric minimum-inhibitory-concentration (MIC) determination in broth cultures, and in TTC-broth culture-test and TTC-normal milk-test. The results of different methods all correlated positively when the entire data was used. However, taking the direct test in mastitic milk as the 'true' result, the total discrepancies varied from 34.7% to 48.8%. Antibacterial activities of the trimethoprim-sulphadoxine combination, and of spiramycin and ampicillin, decreased significantly when nutrient broth was replaced by milk as the test medium. The efficacy of trimethoprim-sulphadoxine as an antibacterial agent was also dependent on the source of milk.

  1. Comparison of methods for in vitro testing of susceptibility of porcine Mycoplasma species to antimicrobial agents.

    PubMed

    Ter Laak, E A; Pijpers, A; Noordergraaf, J H; Schoevers, E C; Verheijden, J H

    1991-02-01

    The MICs of 18 antimicrobial agents used against strains of three porcine Mycoplasma species were determined by a serial broth dilution method. Twenty field strains of M. hyorhinis, ten field strains of M. hyopneumoniae, six field strains of M. flocculare, and the type strains of these species were tested. Twelve field strains and the type strain of M. hyorhinis were also tested by an agar dilution method. Tests were read at various time points. When the broth dilution method was used, the final MIC had to be read 2 days after color changes had stopped. MICs of tetracycline, oxytetracycline, doxycycline, and minocycline were low for the three Mycoplasma species tested. MICs of chlortetracycline were 8 to 16 times higher than MICs of the other tetracyclines. Spiramycin, tylosin, kitasamycin, spectinomycin, tiamulin, lincomycin, and clindamycin were effective against all strains of M. hyorhinis and M. hyopneumoniae. The quinolones were highly effective against M. hyopneumoniae but less effective against M. hyorhinis. The susceptibility patterns for M. hyopneumoniae and M. flocculare were similar.

  2. Comparison of methods for in vitro testing of susceptibility of porcine Mycoplasma species to antimicrobial agents.

    PubMed Central

    Ter Laak, E A; Pijpers, A; Noordergraaf, J H; Schoevers, E C; Verheijden, J H

    1991-01-01

    The MICs of 18 antimicrobial agents used against strains of three porcine Mycoplasma species were determined by a serial broth dilution method. Twenty field strains of M. hyorhinis, ten field strains of M. hyopneumoniae, six field strains of M. flocculare, and the type strains of these species were tested. Twelve field strains and the type strain of M. hyorhinis were also tested by an agar dilution method. Tests were read at various time points. When the broth dilution method was used, the final MIC had to be read 2 days after color changes had stopped. MICs of tetracycline, oxytetracycline, doxycycline, and minocycline were low for the three Mycoplasma species tested. MICs of chlortetracycline were 8 to 16 times higher than MICs of the other tetracyclines. Spiramycin, tylosin, kitasamycin, spectinomycin, tiamulin, lincomycin, and clindamycin were effective against all strains of M. hyorhinis and M. hyopneumoniae. The quinolones were highly effective against M. hyopneumoniae but less effective against M. hyorhinis. The susceptibility patterns for M. hyopneumoniae and M. flocculare were similar. PMID:2024954

  3. Interlaboratory drug susceptibility testing of Mycobacterium tuberculosis by a radiometric procedure and two conventional methods

    SciTech Connect

    Siddiqi, S.H.; Hawkins, J.E.; Laszlo, A.

    1985-12-01

    A total of 224 recent isolates of Mycobacterium tuberculosis from 163 patients selected to have multidrug resistance were tested against streptomycin (SM), isoniazid, rifampin, and ethambutol (EMB) by the rapid radiometric BACTEC method and two conventional proportion methods: the World Health Organization (WHO) method, using Lowenstein-Jensen medium; and the Veterans Administration reference laboratory for mycobacteria (VA) method, using Middlebrook 7H10 agar medium. The results were compared, focusing on the concentrations of the drugs in all three methods. Among the four drugs tested, most of the discrepancies in measured activity were observed with SM and EMB, generally because of differences in the drug concentrations used by the three methods. A 4-micrograms amount of SM in the BACTEC method was found to be slightly less active than 10 micrograms in the VA method and significantly more active than 4 micrograms of dihydrostreptomycin in the WHO method. With EMB, 2.5 micrograms in BACTEC was similar to 5 micrograms in the VA method and 2 micrograms in the WHO method, while 10 micrograms in the BACTEC method was found to be more active than 10 and 2 micrograms in the VA and WHO methods, respectively. To attain close agreement, drug concentrations used in the BACTEC method should be carefully selected when a comparison is to be made with any conventional method employed in a laboratory. Standardization of in vitro susceptibility testing is greatly needed to achieve uniformity among the test methods used to evaluate tuberculosis therapeutics.

  4. Miniaturized Antimicrobial Susceptibility Test by Combining Concentration Gradient Generation and Rapid Cell Culturing

    PubMed Central

    Kim, Samuel C.; Cestellos-Blanco, Stefano; Inoue, Keisuke; Zare, Richard N.

    2015-01-01

    Effective treatment of bacterial infection relies on timely diagnosis and proper prescription of antibiotic drugs. The antimicrobial susceptibility test (AST) is one of the most crucial experimental procedures, providing the baseline information for choosing effective antibiotic agents and their dosages. Conventional methods, however, require long incubation times or significant instrumentation costs to obtain test results. We propose a lab-on-a-chip approach to perform AST in a simple, economic, and rapid manner. Our assay platform miniaturizes the standard broth microdilution method on a microfluidic device (20 × 20 mm) that generates an antibiotic concentration gradient and delivers antibiotic-containing culture media to eight 30-nL chambers for cell culture. When tested with 20 μL samples of a model bacterial strain (E. coli ATCC 25922) treated with ampicillin or streptomycin, our method allows for the determination of minimum inhibitory concentrations consistent with the microdilution test in three hours, which is almost a factor of ten more rapid than the standard method. PMID:27025635

  5. Physician exposure to and attitudes toward advertisements for genetic tests for inherited cancer susceptibility.

    PubMed

    Vadaparampil, Susan Thomas; Wideroff, Louise; Olson, Lorayn; Viswanath, K; Freedman, Andrew N

    2005-05-15

    Commercial marketing materials may serve as a source of information for physicians about genetic testing for inherited cancer susceptibility (GTICS) in addition to medical guidelines, continuing education, and journal articles. The primary purposes of this study were to: (1) determine the percentage of physicians who received advertisements for GTICS early in the diffusion of commercial GTICS (1999-2000); (2) assess associated characteristics; and (3) measure the perceived importance of commercial advertisements and promotions in physicians' decisions to recommend testing to patients. A nationally representative, stratified random sample of 1,251 physicians from the American Medical Association (AMA) Physician Masterfile completed a 15-20 min mixed mode questionnaire that assessed specialty, previous use of genetic tests, practice characteristics, age, and receipt of advertising materials (response rate = 71%). Overall, 27.4% (n = 426) had received advertisements. In multivariate analysis, factors associated with receipt of advertisements included: specialties in obstetrics/gynecology, oncology, or gastroenterology; past GTICS use, and age 50+. One of four felt that advertisements would be important in their decision to recommend GTICS. Study results indicate that physicians, particularly in oncology, obstetrics/gynecology, and gastroenterology, began receiving GTICS advertisements commensurate with the early diffusion of commercially available tests into clinical practice. At that time, one-quarter of the physicians considered advertisements to play an important role in their clinical decision making, suggesting attention to other sources of information and additional factors.

  6. Interlaboratory drug susceptibility testing of Mycobacterium tuberculosis by a radiometric procedure and two conventional methods.

    PubMed Central

    Siddiqi, S H; Hawkins, J E; Laszlo, A

    1985-01-01

    A total of 224 recent isolates of Mycobacterium tuberculosis from 163 patients selected to have multidrug resistance were tested against streptomycin (SM), isoniazid, rifampin, and ethambutol (EMB) by the rapid radiometric BACTEC method and two conventional proportion methods: the World Health Organization (WHO) method, using Lowenstein-Jensen medium; and the Veterans Administration reference laboratory for mycobacteria (VA) method, using Middlebrook 7H10 agar medium. The results were compared, focusing on the concentrations of the drugs in all three methods. Among the four drugs tested, most of the discrepancies in measured activity were observed with SM and EMB, generally because of differences in the drug concentrations used by the three methods. A 4-micrograms amount of SM in the BACTEC method was found to be slightly less active than 10 micrograms in the VA method and significantly more active than 4 micrograms of dihydrostreptomycin in the WHO method. With EMB, 2.5 micrograms in BACTEC was similar to 5 micrograms in the VA method and 2 micrograms in the WHO method, while 10 micrograms in the BACTEC method was found to be more active than 10 and 2 micrograms in the VA and WHO methods, respectively. To attain close agreement, drug concentrations used in the BACTEC method should be carefully selected when a comparison is to be made with any conventional method employed in a laboratory. Standardization of in vitro susceptibility testing is greatly needed to achieve uniformity among the test methods used to evaluate tuberculosis therapeutics. PMID:3934209

  7. FunResDB-A web resource for genotypic susceptibility testing of Aspergillus fumigatus.

    PubMed

    Weber, Michael; Schaer, Jonas; Walther, Grit; Kaerger, Kerstin; Steinmann, Jörg; Rath, Peter-Michael; Spiess, Birgit; Buchheidt, Dieter; Hamprecht, Axel; Kurzai, Oliver

    2017-03-11

    Therapy of invasive aspergillosis is becoming more difficult due to the emergence of azole resistance in Aspergillus fumigatus. A majority of resistant strains carries mutations in the CYP51A gene. Due to a lack of sensitivity of culture-based methods, molecular detection of A. fumigatus has become an important diagnostic tool. We set up the database FunResDB (www.nrz-myk.de/funresdb) to gather all available information about CYP51A-dependent azole resistance from published literature. In summary, the screening resulted in 79 CYP51A variants, which are linked to 59 nonsynonymous mutations. A tailor-made online sequence analysis tool allows for genotypic susceptibility testing of A. fumigatus.

  8. Modified in situ antimicrobial susceptibility testing method based on cyanobacteria chlorophyll a fluorescence.

    PubMed

    Heliopoulos, Nikolaos S; Galeou, Angeliki; Papageorgiou, Sergios K; Favvas, Evangelos P; Katsaros, Fotios K; Stamatakis, Kostas

    2016-02-01

    The chlorophyll a fluorescence based antimicrobial susceptibility testing (AST) method presented in a previous work was based on the measurement of Chl a fluorescence of the gram(-) cyanobacterium Synechococcus sp. PCC 7942. Synechococcus sp. PCC 7942 as a gram(-) bacterium is affected by antibacterial agents via mechanisms affecting all gram(-) bacteria, however, as an exclusively phototrophic organism it would also be affected by photosynthesis inhibitory action of an agent that otherwise has no antibacterial properties. In this report, the method is modified by replacing the exclusively phototrophic Synechococcus sp. PCC 7942 with the Synechocystis sp. PCC 6714, capable of both phototrophic and heterotrophic growth in order to add versatility and better reflect the antibacterial effects of surfaces under study towards nonphotosynthetic bacteria.

  9. 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

  10. Selective reporting of antibiotic susceptibility test results in European countries: an ESCMID cross-sectional survey.

    PubMed

    Pulcini, Céline; Tebano, Gianpiero; Mutters, Nico T; Tacconelli, Evelina; Cambau, Emmanuelle; Kahlmeter, Gunnar; Jarlier, Vincent

    2017-02-01

    Selective reporting of antibiotic susceptibility test (AST) results is one possible laboratory-based antibiotic stewardship intervention. The primary aim of this study was to identify where and how selective reporting of AST results is implemented in Europe both in inpatient and in outpatient settings. An ESCMID cross-sectional, self-administered, internet-based survey was conducted among all EUCIC (European Committee on Infection Control) or EUCAST (European Committee on Antimicrobial Susceptibility Testing) national representatives in Europe and Israel. Of 38 countries, 36 chose to participate in the survey. Selective reporting of AST results was implemented in 11/36 countries (31%), was partially implemented in 4/36 (11%) and was limited to local initiatives or was not adopted in 21/36 (58%). It was endorsed as standard of care by health authorities in only three countries. The organisation of selective reporting was everywhere discretionally managed by each laboratory, with a pronounced intra- and inter-country variability. The most frequent application was in uncomplicated community-acquired infections, particularly urinary tract and skin and soft-tissue infections. The list of reported antibiotics ranged from a few first-line options, to longer reports where only last-resort antibiotics were hidden. Several barriers to implementation were reported, mainly lack of guidelines, poor system support, insufficient resources, and lack of professionals' capability. In conclusion, selective reporting of AST results is poorly implemented in Europe and is applied with a huge heterogeneity of practices. Development of an international framework, based on existing initiatives and identified barriers, could favour its dissemination as one important element of antibiotic stewardship programmes.

  11. 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.

  12. Disk diffusion antimicrobial susceptibility testing of members of the family Legionellaceae including erythromycin-resistant variants of Legionella micdadei.

    PubMed Central

    Dowling, J N; McDevitt, D A; Pasculle, A W

    1984-01-01

    Disk diffusion antimicrobial susceptibility testing of members of the family Legionellaceae was accomplished on buffered charcoal yeast extract agar by allowing the bacteria to grow for 6 h before placement of the disks, followed by an additional 42-h incubation period before the inhibitory zones were measured. This system was standardized by comparing the zone sizes with the MICs for 20 antimicrobial agents of nine bacterial strains in five Legionella species and of 19 laboratory-derived, erythromycin-resistant variants of Legionella micdadei. A high, linear correlation between zone size and MIC was found for erythromycin, trimethoprim, penicillin, ampicillin, carbenicillin, cephalothin, cefamandole, cefoxitin, moxalactam, chloramphenicol, vancomycin, and clindamycin. Disk susceptibility testing could be employed to screen Legionella isolates for resistance to any of these antimicrobial agents, of which only erythromycin is known to be efficacious in the treatment of legionellosis. With selected antibiotics, disk susceptibility patterns also appeared to accurately identify to the species level the legionellae. The range of the MICs of the legionellae for rifampin and the aminoglycosides was too small to determine whether the correlation of zone size with MIC was linear. However, laboratory-derived, high-level rifampin-resistant variants of L. micdadei demonstrated no inhibition zone around the rifampin disk, indicating that disk susceptibility testing would likely identify a rifampin-resistant clinical isolate. Of the antimicrobial agents tested, the only agents for which disk susceptibility testing was definitely not possible on buffered charcoal yeast extract agar were oxacillin, the tetracyclines, and the sulfonamides. PMID:6565706

  13. Multicenter evaluation of the BD Phoenix Automated Microbiology System for antimicrobial susceptibility testing of Streptococcus species.

    PubMed

    Richter, Sandra S; Howard, Wanita J; Weinstein, Melvin P; Bruckner, David A; Hindler, Janet F; Saubolle, Michael; Doern, Gary V

    2007-09-01

    This multicenter study evaluated the BD Phoenix Automated Microbiology System STREP panel (BD Diagnostic Systems). Antimicrobial susceptibility testing (AST) with 13 agents was performed on 2,013 streptococci (938 Streptococcus pneumoniae isolates; 396 group B streptococci [GBS]; 369 viridans group streptococci [VGS]; 290 beta-hemolytic streptococcus groups A, C, and G; and 20 other streptococci) with the Phoenix system and a broth microdilution reference method. Clinical and challenge isolates were tested against cefepime, cefotaxime (CTX), ceftriaxone (CTR), clindamycin (CLI), erythromycin (ERY), gatifloxacin, levofloxacin, linezolid, meropenem, penicillin (PEN), tetracycline (TET), trimethoprim-sulfamethoxazole, and vancomycin. Clinical isolates with major errors or very major errors (VMEs) were retested in duplicate by both methods. The final results for clinical isolates showed the following trends. For all of the organism-antimicrobial agent combinations tested, categorical agreement (CA) was 92 to 100%, with one exception-VGS-PEN (87% CA; all errors were minor). For S. pneumoniae, there was one major error with CLI (0.1%) and one or two VMEs with CTX (4%), CTR (4.5%), ERY (0.9%), and TET (0.7%). For groups A, C, and G, the CA was 97 to 100% and the only VMEs were resolved by additional reference laboratory testing. For GBS, there was only one VME (TET, 0.3%) and D-zone testing of 23 isolates with CLI major errors (one isolate unavailable) revealed inducible CLI resistance. For VGS, the major error rates were 0 to 3% and VMEs occurred with seven agents (3.5 to 7.1%). The mean times required for organism groups to generate results ranged from 8.4 to 9.4 h. The Phoenix system provided reliable and rapid AST results for most of the organism-antimicrobial agent combinations tested.

  14. Archival-grade optical disc design and international standards

    NASA Astrophysics Data System (ADS)

    Fujii, Toru; Kojyo, Shinichi; Endo, Akihisa; Kodaira, Takuo; Mori, Fumi; Shimizu, Atsuo

    2015-09-01

    Optical discs currently on the market exhibit large variations in life span among discs, making them unsuitable for certain business applications. To assess and potentially mitigate this problem, we performed accelerated degradation testing under standard ISO conditions, determined the probable disc failure mechanisms, and identified the essential criteria necessary for a stable disc composition. With these criteria as necessary conditions, we analyzed the physical and chemical changes that occur in the disc components, on the basis of which we determined technological measures to reduce these degradation processes. By applying these measures to disc fabrication, we were able to develop highly stable optical discs.

  15. Calibration of fusidic acid disk diffusion susceptibility testing of Staphylococcus areus.

    PubMed

    Olsson-Liljequist, Barbro; Kõljalg, Siiri; Karlsson, Inga; Kronvall, Göran

    2002-10-01

    Single strain regression analysis, SRA, was used to calibrate disk diffusion fusidic acid susceptibility testing of Staphylococcus aureus in two laboratories using different standard methods but the same interpretative MIC limits. SRA equation constants were calculated using five different fusidic acid disk contents (1.5, 5, 15, 50, 150 microg). These disks were tested on five separate occasions against quality control strain S. aureus ATCC 29213. The National Committee for Clinical Laboratory Standards (NCCLS) method was employed in Tartu, Estonia (TE) and the Swedish Reference Group for Antibiotics (SRGA) method in Sweden at the Karolinska Hospital (KS). SRA constants obtained were used for calculating zone breakpoints corresponding to MIC breakpoints recommended by the SRGA (S < or = 0.5 mg/L, R > or = 1 mg/L). Zone diameter histograms from KS, performed with a 50 microg disk, and from TE, using a 10 microg disk, showed a clustering of wild type strains around 41 mm and 30 mm, respectively, reflecting differences in methodology. Zone breakpoints calculated from the equations were validated by comparison with the histograms. Breakpoints were also calculated for a suggested lower disk content in Sweden, 10 microg, and validated in tests of clinical isolates and by histogram analysis.

  16. Novel two-round phenotypic assay for protease inhibitor susceptibility testing of recombinant and primary HIV-1 isolates.

    PubMed

    Puertas, Maria C; Buzón, Maria J; Ballestero, Mònica; Van Den Eede, Peter; Clotet, Bonaventura; Prado, Julia G; Martinez-Picado, Javier

    2012-12-01

    Antiretroviral drug susceptibility tests facilitate therapeutic management of HIV-1-infected patients. Although genotyping systems are affordable, inaccuracy in the interpretation of complex mutational patterns may limit their usefulness. Currently available HIV-1 phenotypic assays are based on the generation of recombinant viruses in which the specific viral gene of interest, derived from a patient plasma sample, is cloned into a susceptible genetic viral backbone prior to in vitro drug susceptibility evaluation. Nevertheless, in the case of protease inhibitors, not only are mutations in the HIV-1 protease-coding region involved in resistance, but the role of Gag in drug susceptibility has also recently been reported. In order to avoid the inherent limitations resulting from partial cloning of the viral genome, we designed and evaluated a new experimental strategy to test the in vitro susceptibility of primary viral isolates to protease inhibitors. Our protocol, which is based on a two-round infection protocol using the reporter TZM-bl cell line, showed a good correlation with genotypic resistance prediction and with the Antivirogram phenotypic assay, in both protease-recombinant viruses and primary viral isolates. The protocol is suitable for any HIV-1 subtype and enables rapid in-house measurement of protease inhibitor susceptibility, thus making it possible to evaluate the concomitant effects of both patient-derived gag and protease-coding regions.

  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. Validation of a modified Kirby-Bauer disk diffusion method for metronidazole susceptibility testing of Helicobacter pylori.

    PubMed

    Midolo, P D; Turnidge, J; Lambert, J R; Bell, J M

    1995-03-01

    Triple antimicrobial therapy that includes metronidazole has been recommended as a first-line therapy for Helicobacter pylori because it has the highest eradication rates. However, resistance in H. pylori to metronidazole has been reported worldwide and its presence may reduce the efficacy of triple therapy. Various methods for testing H. pylori against metronidazole have been used including agar dilution, disk diffusion and the Etest but there has been little standardization of methods. One hundred isolates of H. pylori from different patients were tested for susceptibility to metronidazole by agar dilution, Etest and disk diffusion (5 micrograms disk). The agar dilution results confirmed the MIC susceptibility breakpoint to be < or = 8 micrograms/ml. Using this breakpoint there was close agreement (98%) between Etest and agar dilution results. For susceptible strains, MICs by E-test were generally one twofold dilution lower. Using the error-rate bounded method, agreement between disk diffusion zone diameter and MIC was 98% for agar dilution with breakpoints of > or = 12 mm and < or = 8 micrograms/ml and 100% for Etest with breakpoints of > or = 12 mm and < or = 8 micrograms/ml. The Etest discriminated better than agar dilution between susceptible and resistant strains and was simple to perform. The disk diffusion test is a reliable and cheaper alternative to the Etest with susceptibility being a zone diameter > or = 12 mm with a 5 micrograms disk. The prevalence of metronidazole resistance in this study was 40% by Etest.

  19. Susceptibility to Welding Cracking, Welding Sensitivity, Susceptibility to Welding Seam Cracking, and Test Methods for These Failures

    NASA Technical Reports Server (NTRS)

    Zeyen, K. L.

    1949-01-01

    In the years after the First World war a very rapid development, which even today has by no means come to an end, took place in the field of welding; here also, as in most technical innovations, failures made their appearance. Thereupon comprehensive Investigations were undertaken by steel manufacturers and consumers with cooperation of the authorities. b most cases the reasons for failure could be determined and eliminated and further occurrences avoided by the use of new test methods.

  20. Bile Culture and Susceptibility Testing of Malignant Biliary Obstruction via PTBD

    SciTech Connect

    Yu Haipeng; Guo Zhi Xing Wenge; Guo Xiuying; Liu Fang; Li Baoguo

    2012-10-15

    Purpose: To assess the information obtained by bile culture and susceptibility testing for malignant biliary obstruction by a retrospective one-center study. Methods: A total of 694 patients with malignant biliary obstruction received percutaneous transhepatic biliary drainage during the period July 2003 to September 2010, and subsequently, bile specimens were collected during the procedure. Among the 694 patients, 485 were men and 209 were women, ranging in age from 38 to 78 years (mean age 62 years). Results: A total of 42.9% patients had a positive bile culture (298 of 694). Further, 57 species of microorganisms and 342 strains were identified; gram-positive bacteria accounted for 50.9% (174 of 342) and gram-negative bacteria accounted for 41.5% (142 of 342) of these strains. No anaerobes were obtained by culture during this study. The most common microorganisms were Enterococcus faecalis (41 of 342, 11.9%), Escherichia coli (34 of 342, 9.9%), Klebsiella pneumoniae (28 of 342, 8.2%), Staphylococcus epidermidis (19 of 342, 5.5%), Enterococcus (18 of 342, 5.3%), and Enterobacter cloacae (16 of 342, 4.7%). The percentage of {beta}-lactamase-producing gram-positive bacteria was 27.6% (48 of 174), and the percentage of gram-negative bacteria was 19.7% (28 of 142). The percentage of enzyme-producing Escherichia coli was 61.7% (21 of 34). Conclusion: The bile cultures in malignant biliary obstruction are different from those in the Tokyo Guidelines and other benign biliary obstruction researches, which indicates that a different antibacterial therapy should be applied. Thus, knowledge of the antimicrobial susceptibility data could aid in the better use of antibiotics for the empirical therapy of biliary infection combined with malignant biliary obstruction.

  1. Redundant disc

    NASA Technical Reports Server (NTRS)

    Barack, W. N.; Domas, P. A.; Beekman, S. W. (Inventor)

    1978-01-01

    A rotatable disc is described that consists of parallel plates tightly joined together for rotation about a hub. Each plate is provided with several angularly projecting spaced lands. The lands of each plate are interposed in alternating relationship between the lands of the next adjacent plate. In this manner, circumferential displacement of adjacent sectors in any one plate is prevented in the event that a crack develops. Each plate is redundantly sized so that, in event of structural failure of one plate, the remaining plates support a proportionate share of the load of the failed plate. The plates are prevented from separating laterally through the inclusion of generally radially extending splines which are inserted to interlock cooperating, circumferentially adjacent lands.

  2. Modified protocol for drug susceptibility testing of MGIT cultures of Mycobacterium tuberculosis by the MGIT 960.

    PubMed

    Adami, Aline Gois; Gallo, Juliana Failde; Pinhata, Juliana Maira Watanabe; Martins, Maria Conceição; Giampaglia, Carmen Maria Saraiva; de Oliveira, Rosangela Siqueira

    2017-02-01

    A rapid detection of resistance in Mycobacterium tuberculosis is crucial for management and control of tuberculosis. This study evaluated a more rapid and cost-effective drug susceptibility testing (DST) protocol using primary isolates of M. tuberculosis in mycobacteria growth indicator tube (MGIT). Ninety-four M. tuberculosis isolates in MGIT were subjected to DST by the manufacturer's method, i.e., primary isolates were subcultured and DST was performed from positive cultures for a maximum of 5days; and by our modified method, i.e., DST was performed directly from primary MGIT cultures positive for more than 5days. Results were concordant for 76 (81%) isolates. Agreement between both methods was 92.0%, 98.9%, 97.7%, and 95.5% for streptomycin, isoniazid, rifampicin, and ethambutol, respectively. Six isolates failed to grow on the recommended method, including 3 resistant isolates. Not performing subculture of primary M. tuberculosis isolates yields reliable results, decreasing the turnaround time and the cost of the test.

  3. Eclipse Mapping of Accretion Discs

    NASA Astrophysics Data System (ADS)

    Baptista, R.

    The eclipse mapping method is an inversion technique that makes use of the information contained in eclipse light curves to probe the structure, the spectrum and the time evolution of accretion discs. In this review I present the basics of the method and discuss its different implementations. I summarize the most important results obtained to date and discuss how they have helped to improve our understanding of accretion physics, from testing the theoretical radial brightness temperature distribution and measuring mass accretion rates to showing the evolution of the structure of a dwarf novae disc throughout its outburst cycle, from isolating the spectrum of a disc wind to revealing the geometry of disc spiral shocks. I end with an outline of the future prospects.

  4. Multicenter evaluation of fully automated BACTEC Mycobacteria Growth Indicator Tube 960 system for susceptibility testing of Mycobacterium tuberculosis.

    PubMed

    Bemer, Pascale; Palicova, Frantiska; Rüsch-Gerdes, Sabine; Drugeon, Henri B; Pfyffer, Gaby E

    2002-01-01

    The reliability of the BACTEC Mycobacteria Growth Indicator Tube (MGIT) 960 system for testing of Mycobacterium tuberculosis susceptibility to the three front-line drugs (isoniazid [INH], rifampin [RIF], and ethambutol [EMB]) plus streptomycin (STR) was compared to that of the BACTEC 460 TB system. The proportion method was used to resolve discrepant results by an independent arbiter. One hundred and ten strains were tested with an overall agreement of 93.5%. Discrepant results were obtained for seven strains (6.4%) with INH (resistant by BACTEC MGIT 960; susceptible by BACTEC 460 TB), for one strain (0.9%) with RIF (resistant by BACTEC MGIT 960; susceptible by BACTEC 460 TB), for seven strains (6.4%) with EMB (six resistant by BACTEC MGIT 960 and susceptible by BACTEC 460 TB; one susceptible by BACTEC MGIT 960 and resistant by BACTEC 460 TB), and for 19 strains (17.3%) with STR (resistant by BACTEC MGIT 960 and susceptible by BACTEC 460 TB). After resolution of discrepant results, the sensitivity of the BACTEC MGIT 960 system was 100% for all four drugs and specificity ranged from 89.8% for STR to 100% for RIF. Turnaround times were 4.6 to 11.7 days (median, 6.5 days) for BACTEC MGIT 960 and 4.0 to 10.0 days (median, 7.0 days) for BACTEC 460 TB. These data demonstrate that the fully automated and nonradiometric BACTEC MGIT 960 system is an accurate method for rapid susceptibility testing of M. tuberculosis.

  5. Multicenter Evaluation of Fully Automated BACTEC Mycobacteria Growth Indicator Tube 960 System for Susceptibility Testing of Mycobacterium tuberculosis

    PubMed Central

    Bemer, Pascale; Palicova, Frantiska; Rüsch-Gerdes, Sabine; Drugeon, Henri B.; Pfyffer, Gaby E.

    2002-01-01

    The reliability of the BACTEC Mycobacteria Growth Indicator Tube (MGIT) 960 system for testing of Mycobacterium tuberculosis susceptibility to the three front-line drugs (isoniazid [INH], rifampin [RIF], and ethambutol [EMB]) plus streptomycin (STR) was compared to that of the BACTEC 460 TB system. The proportion method was used to resolve discrepant results by an independent arbiter. One hundred and ten strains were tested with an overall agreement of 93.5%. Discrepant results were obtained for seven strains (6.4%) with INH (resistant by BACTEC MGIT 960; susceptible by BACTEC 460 TB), for one strain (0.9%) with RIF (resistant by BACTEC MGIT 960; susceptible by BACTEC 460 TB), for seven strains (6.4%) with EMB (six resistant by BACTEC MGIT 960 and susceptible by BACTEC 460 TB; one susceptible by BACTEC MGIT 960 and resistant by BACTEC 460 TB), and for 19 strains (17.3%) with STR (resistant by BACTEC MGIT 960 and susceptible by BACTEC 460 TB). After resolution of discrepant results, the sensitivity of the BACTEC MGIT 960 system was 100% for all four drugs and specificity ranged from 89.8% for STR to 100% for RIF. Turnaround times were 4.6 to 11.7 days (median, 6.5 days) for BACTEC MGIT 960 and 4.0 to 10.0 days (median, 7.0 days) for BACTEC 460 TB. These data demonstrate that the fully automated and nonradiometric BACTEC MGIT 960 system is an accurate method for rapid susceptibility testing of M. tuberculosis. PMID:11773109

  6. Antimicrobial susceptibility testing of Streptococcus pneumoniae and Haemophilus influenzae --internal quality control as a quality tool on a national level.

    PubMed

    Kärpänoja, Pauliina; Nissinen, Antti; Huovinen, Pentti; Sarkkinen, Hannu

    2013-06-01

    Knowledge of the quality and conformity of antimicrobial resistance data is important for comparing resistance rates regionally and over time. In this study, we have evaluated these features of the Finnish national susceptibility surveillance data for two respiratory tract pathogens, Streptococcus pneumoniae and Haemophilus influenzae. For this purpose internal quality control results for two isolates (S. pneumoniae ATCC 49619 and H. influenzae ATCC 49247) were analyzed from 21 clinical microbiology laboratories over a 3-year period. The results show that standardization of the susceptibility testing methods has proceeded well. The number of protocols used for susceptibility testing has declined (from seventeen methods to two with S. pneumoniae and from eleven to three with H. influenzae) and the reproducibility is good. Nevertheless, we noticed that a few laboratories test and report susceptibility results without defined break-points and even include antimicrobials with questionable therapeutic effect. Another non-compliance with the standard was a lack of a regular control system to verify the attainment of the intended quality of results in some laboratories. Interlaboratory analysis of quality control results is a good way to evaluate the quality and conformity of national resistance data. Finnish laboratories have produced very reproducible and accurate susceptibility results in the pre-EUCAST period, which ended in 2011.

  7. Rapid colorimetric testing for pyrazinamide susceptibility of M. tuberculosis by a PCR-based in-vitro synthesized pyrazinamidase method.

    PubMed

    Zhou, Man; Geng, Xuelei; Chen, Jun; Wang, Xude; Wang, Dianbing; Deng, Jiaoyu; Zhang, Zhiping; Wang, Weihua; Zhang, Xian-En; Wei, Hongping

    2011-01-01

    Pyrazinamide (PZA) is an important first-line anti-tuberculosis drug. But PZA susceptibility test is challenging because PZA activity is optimal only in an acid environment that inhibits the growth of M. tuberculosis. For current phenotypic methods, inconsistent results between different labs have been reported. Direct sequencing of pncA gene is being considered as an accurate predictor for PZA susceptibility, but this approach needs expensive sequencers and a mutation database to report the results. An in-vitro synthesized Pyrazinamidase (PZase) assay was developed based on PCR amplification of pncA gene and an in vitro wheat germ system to express the pncA gene into PZase. The activity of the synthesized PZase was used as an indicator for PZA susceptibility. Fifty-one clinical isolates were tested along with pncA sequencing and the BACTEC MGIT 960 methods. The in-vitro synthesized PZase assay was able to detect PZA susceptibility of M. tuberculosis within 24 h through observing the color difference either by a spectrometer or naked eyes. This method showed agreements of 100% (33/33) and 88% (14/16) with the pncA sequencing method, and agreements of 96% (27/28) and 65% (15/23) with the BACTEC MGIT 960 method, for susceptible and resistant strains, respectively. The novel in-vitro synthesized PZase assay has significant advantages over current methods, such as its fast speed, simplicity, no need for expensive equipment, and the potentials of being a direct test, predicting resistance level and easy reading results by naked eyes. After confirmation by more clinical tests, this method may provide a radical change to the current PZA susceptibility assays.

  8. Antimicrobial susceptibility testing of Gram-positive and -negative bacterial isolates directly from spiked blood culture media with Raman spectroscopy.

    PubMed

    Dekter, H E; Orelio, C C; Morsink, M C; Tektas, S; Vis, B; Te Witt, R; van Leeuwen, W B

    2017-01-01

    Patients suffering from bacterial bloodstream infections have an increased risk of developing systematic inflammatory response syndrome (SIRS), which can result in rapid deterioration of the patients' health. Diagnostic methods for bacterial identification and antimicrobial susceptibility tests are time-consuming. The aim of this study was to investigate whether Raman spectroscopy would be able to rapidly provide an antimicrobial susceptibility profile from bacteria isolated directly from positive blood cultures. First, bacterial strains (n = 133) were inoculated in tryptic soy broth and incubated in the presence or absence of antibiotics for 5 h. Antimicrobial susceptibility profiles were analyzed by Raman spectroscopy. Subsequently, a selection of strains was isolated from blood cultures and analyzed similarly. VITEK®2 technology and broth dilution were used as the reference methods. Raman spectra from 67 antibiotic-susceptible strains showed discriminatory spectra in the absence or at low concentrations of antibiotics as compared to high antibiotic concentrations. For 66 antibiotic-resistant strains, no antimicrobial effect was observed on the bacterial Raman spectra. Full concordance with VITEK®2 data and broth dilution was obtained for the antibiotic-susceptible strains, 68 % and 98 %, respectively, for the resistant strains. Discriminative antimicrobial susceptibility testing (AST) profiles were obtained for all bacterial strains isolated from blood cultures, resulting in full concordance with the VITEK®2 data. It can be concluded that Raman spectroscopy is able to detect the antimicrobial susceptibility of bacterial species isolated from a positive blood culture bottle within 5 h. Although Raman spectroscopy is cheap and rapid, further optimization is required, to fulfill a great promise for future AST profiling technology development.

  9. Antimicrobial susceptibility testing of pneumococci: determination of Kirby-Bauer breakpoints for penicillin G, erythromycin, clindamycin, tetracycline, chloramphenicol, and rifampin.

    PubMed

    Jacobs, M R; Mithal, Y; Robins-Browne, R M; Gaspar, M N; Koornhof, H J

    1979-08-01

    Antimicrobial susceptibility testing of pneumococci is now essential to monitor for the presence of resistance to agents such as the penicillins, macrolides, lincomycins, chloramphenicol, and tetracycline. In this study, clinical isolates of a selection of resistant South African strains were tested for antimicrobial susceptibility by minimal inhibitory concentration (MIC) determination and by a modified Kirby-Bauer disk diffusion technique, using Mueller-Hinton medium supplemented with 5% horse blood. Disk diffusion breakpoints were determined for penicillin G, erythromycin, clindamycin, tetracycline, chloramphenicol, and rifampin. Reliable results were obtained on disk diffusion for all these agents except for penicillin G. With 6-mug penicillin G disks, zones of strains with intermediate penicillin susceptibility overlapped those of sensitive and resistant strains. With 5-mug methicillin disks, clearer separation of strains based on susceptibility to penicillin G occurred. Strains with zones of <35 mm around penicillin G disks and <25 mm around methicillin disks should have penicillin G MICs determined to confirm their resistance to penicillin G. In view of the potential for pneumococci to be resistant to the agents used in this study, antimicrobial susceptibility of all clinically significant isolates should be determined.

  10. Bacterial viability and antibiotic susceptibility testing with SYTOX green nucleic acid stain.

    PubMed Central

    Roth, B L; Poot, M; Yue, S T; Millard, P J

    1997-01-01

    A fluorescent nucleic acid stain that does not penetrate living cells was used to assess the integrity of the plasma membranes of bacteria. SYTOX Green nucleic acid stain is an unsymmetrical cyanine dye with three positive charges that is completely excluded from live eukaryotic and prokaryotic cells. Binding of SYTOX Green stain to nucleic acids resulted in a > 500-fold enhancement in fluorescence emission (absorption and emission maxima at 502 and 523 nm, respectively), rendering bacteria with compromised plasma membranes brightly green fluorescent. SYTOX Green stain is readily excited by the 488-nm line of the argon ion laser. The fluorescence signal from membrane-compromised bacteria labeled with SYTOX Green stain was typically > 10-fold brighter than that from intact organisms. Bacterial suspensions labeled with SYTOX Green stain emitted green fluorescence in proportion to the fraction of permeabilized cells in the population, which was quantified by microscopy, fluorometry, or flow cytometry. Flow cytometric and fluorometric approaches were used to quantify the effect of beta-lactam antibiotics on the cell membrane integrity of Escherichia coli. Detection and discrimination of live and permeabilized cells labeled with SYTOX Green stain by flow cytometry were markedly improved over those by propidium iodide-based tests. These studies showed that bacterial labeling with SYTOX Green stain is an effective alternative to conventional methods for measuring bacterial viability and antibiotic susceptibility. PMID:9172364

  11. A Low Cost/Low Power Open Source Sensor System for Automated Tuberculosis Drug Susceptibility Testing

    PubMed Central

    Kim, Kyukwang; Kim, Hyeong Keun; Lim, Hwijoon; Myung, Hyun

    2016-01-01

    In this research an open source, low power sensor node was developed to check the growth of mycobacteria in a culture bottle with a nitrate reductase assay method for a drug susceptibility test. The sensor system reports the temperature and color sensor output frequency change of the culture bottle when the device is triggered. After the culture process is finished, a nitrite ion detecting solution based on a commercial nitrite ion detection kit is injected into the culture bottle by a syringe pump to check bacterial growth by the formation of a pigment by the reaction between the solution and the color sensor. Sensor status and NRA results are broadcasted via a Bluetooth low energy beacon. An Android application was developed to collect the broadcasted data, classify the status of cultured samples from multiple devices, and visualize the data for the end users, circumventing the need to examine each culture bottle manually during a long culture period. The authors expect that usage of the developed sensor will decrease the cost and required labor for handling large amounts of patient samples in local health centers in developing countries. All 3D-printerable hardware parts, a circuit diagram, and software are available online. PMID:27338406

  12. Direct identification and susceptibility testing of positive blood cultures using high speed cold centrifugation and Vitek II system.

    PubMed

    Bazzi, Ali M; Rabaan, Ali A; Fawarah, Mahmoud M; Al-Tawfiq, Jaffar A

    2016-06-13

    Compared to routine isolated colony-based methods, direct testing of bacterial pellets from positive blood cultures reduces turnaround time for reporting of antibiotic susceptibility. The aim of this study was to compare the accuracy, and precision, of a rapid method for direct identification and susceptibility testing of blood cultures with the routine method used in our laboratory, using Vitek 2. A total of 60 isolates were evaluated using the candidate and the routine method. The candidate method had 100% accuracy for the identification of Gram negative bacteria, Staphylococcus and Enterococcus, 50% for Streptococcus and 33.3% for Corynebacterium species. Susceptibility testing of Gram negative isolates yielded 98-100% essential agreement. For Staphylococcus and Enterococcus isolates, essential agreement was 100% for 17 antibiotics except for moxifloxacin. Direct testing of blood culture samples with Vitek 2 produced reliable identification and susceptibility results 18-24h sooner for aerobic/anaerobic facultative Gram-negative bacteria and Gram-positive Staphylococcus and Enterococcus strains.

  13. [Application of the BACspreader™ Microbe Dispersion Counter in drug susceptibility test on Mycobacterium tuberculosis].

    PubMed

    Jiang, Y; Li, J; Zhang, Y Y; Wu, J; Wang, L L; Yu, C L; Shen, X; Zhu, G F

    2017-04-12

    Objective: To evaluate the application of the BACspreader™ Microbe Dispersion Counter in drug susceptibility test (DST) on Mycobacterium tuberculosis (MTB). Methods: The MTB strains were dispersed and diluted to 1.0 McFarland standard turbidity, by means of BACspreader™ Microbe Dispersion Counter and manual grinding method, respectively. The bacterial dispersion effect and bacterial activity were tested by microscope and colony counting method. During Jan. 2015 to June 2015, a total of 726 isolates of MTB were collected in all district tuberculosis hospitals of Shanghai. The bacterial suspension dispersed by instrument and manual grinding, were inoculated in slant medium for DST (Proportion Method), and then incubated in 37 ℃ incubator for 28 days and the DST results were reported. The effects of the 2 different bacterial dispersion methods were compared by comparing DST results and counting the bacterial colony which grew in high and low concentration control media. Paired chi-square test was used for statistical analysis, and the significance level was 0.05. Results: Compared to the manual grinding method, the MTB colony could be better dispersed by BACspreader™ Microbe Dispersion Counter, without reducing the bacterial activity. The DST results of 726 mycobacterial isolates were the same by different bacterial dispersion methods. The count of bacterial colony growing in high concentration control medium was significantly different between of the 2 dispersion methods (χ(2)=8.0, P<0.01). When counting the bacterial colony growing in low concentration control medium, the numerable rate was 97.7% by BACspreader™ Microbe Dispersion Counter, and 4.3% by manual grinding method; the difference being significant between the 2 dispersion methods (χ(2)=674, P<0.001). Conclusions: Compared to the manual grinding method, the slant medium inoculated with bacterial suspension obtained by BACspreader™ Microbe Dispersion Counter had better countability in low

  14. Verification of an Automated, Digital Dispensing Platform for At-Will Broth Microdilution-Based Antimicrobial Susceptibility Testing

    PubMed Central

    Smith, Kenneth P.

    2016-01-01

    With rapid emergence of multidrug-resistant bacteria, there is often a need to perform susceptibility testing for less commonly used or newer antimicrobial agents. Such testing can often be performed only by using labor-intensive, manual dilution methods and lies outside the capacity of most clinical labs, necessitating reference laboratory testing and thereby delaying the availability of susceptibility data. To address the compelling clinical need for microbiology laboratories to perform such testing in-house, we explored a novel, automated, at-will broth microdilution-based susceptibility testing platform. Specifically, we used the modified inkjet printer technology in the HP D300 digital dispensing system to dispense, directly from stock solutions into a 384-well plate, the 2-fold serial dilution series required for broth microdilution testing. This technology was combined with automated absorbance readings and data analysis to determine MICs. Performance was verified by testing members of the Enterobacteriaceae for susceptibility to ampicillin, cefazolin, ciprofloxacin, colistin, gentamicin, meropenem, and tetracycline in comparison to the results obtained with a broth microdilution reference standard. In precision studies, essential and categorical agreement levels were 96.8% and 98.3%, respectively. Furthermore, significantly fewer D300-based measurements were outside ±1 dilution from the modal MIC, suggesting enhanced reproducibility. In accuracy studies performed using a panel of 80 curated clinical isolates, rates of essential and categorical agreement and very major, major, and minor errors were 94%, 96.6%, 0%, 0%, and 3.4%, respectively. Based on these promising initial results, it is anticipated that the D300-based methodology will enable hospital-based clinical microbiology laboratories to perform at-will broth microdilution testing of antimicrobials and to address a critical testing gap. PMID:27335151

  15. Verification of an Automated, Digital Dispensing Platform for At-Will Broth Microdilution-Based Antimicrobial Susceptibility Testing.

    PubMed

    Smith, Kenneth P; Kirby, James E

    2016-09-01

    With rapid emergence of multidrug-resistant bacteria, there is often a need to perform susceptibility testing for less commonly used or newer antimicrobial agents. Such testing can often be performed only by using labor-intensive, manual dilution methods and lies outside the capacity of most clinical labs, necessitating reference laboratory testing and thereby delaying the availability of susceptibility data. To address the compelling clinical need for microbiology laboratories to perform such testing in-house, we explored a novel, automated, at-will broth microdilution-based susceptibility testing platform. Specifically, we used the modified inkjet printer technology in the HP D300 digital dispensing system to dispense, directly from stock solutions into a 384-well plate, the 2-fold serial dilution series required for broth microdilution testing. This technology was combined with automated absorbance readings and data analysis to determine MICs. Performance was verified by testing members of the Enterobacteriaceae for susceptibility to ampicillin, cefazolin, ciprofloxacin, colistin, gentamicin, meropenem, and tetracycline in comparison to the results obtained with a broth microdilution reference standard. In precision studies, essential and categorical agreement levels were 96.8% and 98.3%, respectively. Furthermore, significantly fewer D300-based measurements were outside ±1 dilution from the modal MIC, suggesting enhanced reproducibility. In accuracy studies performed using a panel of 80 curated clinical isolates, rates of essential and categorical agreement and very major, major, and minor errors were 94%, 96.6%, 0%, 0%, and 3.4%, respectively. Based on these promising initial results, it is anticipated that the D300-based methodology will enable hospital-based clinical microbiology laboratories to perform at-will broth microdilution testing of antimicrobials and to address a critical testing gap.

  16. Accuracy of automated and manual systems for susceptibility testing of Pseudomonas aeruginosa to piperacillin and piperacillin-tazobactam.

    PubMed

    Gagliotti, Carlo; Sarti, Mario; Sabia, Carla; Gargiulo, Raffaele; Rossolini, Gian Maria; Carillo, Carmelina; Cassani, Carla; Cipolloni, Antonio Paolo; Pedna, Federica; Rossi, Maria Rita; Incerti, Silvia Storchi; Testa, Giovanna; Venturelli, Claudia; Moro, Maria Luisa

    2011-01-01

    This study aimed to evaluate the accuracy of routine systems (Vitek2 cards AST-N022 and AST-N026; Kirby Bauer; Etest) for susceptibility testing of Pseudomonas aeruginosa to piperacillin and piperacillin-tazobactam. Vitek2 (card AST-N022) showed the worst performance; the other three methods (Vitek2 card AST-N026, Kirby-Bauer and E-test) performed comparably but never fulfilled the minimal standard proposed by FDA.

  17. [Recommendations from MENSURA for selection of antimicrobial agents for susceptibility testing and criteria for the interpretation of antibiograms].

    PubMed

    2000-03-01

    This document includes the recommendations from the Spanish antibiogram committee (The MENSURA group, Mesa Española de Normalización de la Sensibilidad y Resistencia a los Antimicrobianos, under the auspices of the Sociedad Española de Quimioterapia and Sociedad Española de Enfermedades Infecciosas y Microbiología Clínica) for the selection of antimicrobials for susceptibility testing. Separate tables for each group of organism with proposed susceptibility and resistance breakpoints are updated and comparatively presented with those of other groups, such us NCCLS, CA-SFM and BSAC. The susceptibility breakpoint tends to identify the fully susceptible population, which probably lacks any specific resistance mechanism. The analysis of MIC distributions for different homogeneous populations (same species) is used to define breakpoints for susceptibility. The resistance breakpoint is based on pharmacological and clinical data obtained when the corresponding antibiotic is administered with a conventional schedule. The primary objective of the Spanish MENSURA group is to contribute to the international consensus on the establishment of breakpoints.

  18. 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.

  19. Identification of Streptococcus pneumoniae: Development of a Standardized Protocol for Optochin Susceptibility Testing Using Total Lab Automation

    PubMed Central

    Panitz, Jessica; Burckhardt, Florian; Zimmermann, Stefan

    2017-01-01

    Purpose. Optochin susceptibility is one parameter used in the laboratory to identify Streptococcus pneumoniae. However, a single standardized procedure does not exist. Optochin is included neither in the current EUCAST breakpoint tables nor in the CLSI performance standards for antimicrobial susceptibility testing. We wanted to establish an evidence-based protocol for optochin testing for our Total Lab Automation. Methods. We tested seven different agars and four different reading time points (7 h, 12 h, 18 h, and 24 h). To accommodate for serotype diversity, all tests were done with 99 different strains covering 34 different serotypes of S. pneumoniae. We calculated a multivariable linear regression using data from 5544 inhibition zones. Results. Reading was possible for all strains at 12 h. Agar type and manufacturer influenced the size of the inhibition zones by up to 2 mm and they varied considerably depending on serotype (up to 3 mm for serotype 3). Depending on agar and reading time point, up to 38% of inhibition zones were smaller than the cut-off of 14 mm; that is, the result of the test was false-negative. Conclusions. Shortening incubation time from 24 h to 12 h for optochin susceptibility testing is feasible. Agar and incubation time have to be chosen carefully to avoid false-negative results.

  20. Clarithromycin Susceptibility Testing of Mycobacterium avium Complex Using 2,3-Diphenyl-5-thienyl-(2)-tetrazolium Chloride Microplate Assay with Middlebrook 7H9 Broth

    PubMed Central

    Park, Young Kil; Koh, Won-Jung; Kim, Shin Ok; Shin, Sonya; Kim, Bum Joon; Cho, Sang-Nae; Lee, Sun Min

    2009-01-01

    A series of 119 Mycobacterium avium complex isolates were subjected to clarithromycin susceptibility testing using microplates containing 2,3-diphenyl-5-thienyl-(2)-tetrazolium chloride (STC). Among 119 isolates, 114 (95.8%) were susceptible to clarithromycin and 5 were resistant according to the new and the standard method. STC counts the low cost and reduces the number of procedures needed for susceptibility testing. PMID:19543518

  1. Short report: Seroprevalence of human leptospirosis in Reunion Island (Indian Ocean) assessed by microscopic agglutination test on paper disc-absorbed whole blood.

    PubMed

    Desvars, Amélie; Gigan, Jimmy; Hoarau, Géraldine; Gérardin, Patrick; Favier, François; Michault, Alain

    2011-12-01

    In the last decade, leptospirosis has emerged as a globally important infectious disease. Humans most commonly become infected through occupational, recreational, or domestic contact with the urine of carrier animals, either directly or through contaminated water or soil. The disease occurs in urban areas of industrialized and developing countries as well as rural regions worldwide. We present a retrospective study conducted in 2006 on 2,269 randomly selected Reunion Island inhabitants. Blood sampling was performed on individual blotting papers, and microscopic agglutination test (MAT) was conducted on paper disc-absorbed (PDA) blood. We showed that seroprevalence of leptospirosis was 0.66% ± 0.34 in the global population of Reunion Island, which is 1.78 lower than the seroprevalence estimated 20 years before. The serological method is described, and the results discussion focuses on methodology and socio-economic factors.

  2. Clinical application of micronucleus test: a case-control study on the prediction of breast cancer risk/susceptibility.

    PubMed

    Bolognesi, Claudia; Bruzzi, Paolo; Gismondi, Viviana; Volpi, Samantha; Viassolo, Valeria; Pedemonte, Simona; Varesco, Liliana

    2014-01-01

    The micronucleus test is a well-established DNA damage assay in human monitoring. The test was proposed as a promising marker of cancer risk/susceptibility mainly on the basis of studies on breast cancer. Our recent meta-analysis showed that the association between micronuclei frequency, either at baseline or after irradiation, and breast cancer risk or susceptibility, has been evaluated in few studies of small size, with inconsistent results. The aim of the present study is to investigate the role of micronucleus assay in evaluating individual breast cancer susceptibility. Two-hundred and twenty untreated breast cancer patients and 295 female controls were enrolled in the study. All women were characterized for cancer family history and 155 subjects were evaluated for the presence of BRCA mutations. Micronuclei frequency was evaluated at baseline and after irradiation with 1-Gy gamma rays from a 137Cs source. The results show a non significant increase of frequency of micronucleated binucleated lymphocytes in cancer patients compared with the controls at baseline (Mean (S.E.): 16.8 (0.7) vs 15.7 (0.5), but not after irradiation (Mean (S.E.): 145.8 (3.0) vs 154.0 (2.6)). Neither a family history of breast cancer nor the presence of a pathogenic mutation in BRCA1/2 genes were associated with an increased micronuclei frequency. Our results do not support a significant role of micronucleus frequency as a biomarker of breast cancer risk/susceptibility.

  3. Evaluation of BACTEC Mycobacteria Growth Indicator Tube (MGIT 960) Automated System for Drug Susceptibility Testing of Mycobacterium tuberculosis

    PubMed Central

    Ardito, Fausta; Posteraro, Brunella; Sanguinetti, Maurizio; Zanetti, Stefania; Fadda, Giovanni

    2001-01-01

    The reliability of the BACTEC MGIT 960 system, an automated version of the Mycobacteria Growth Indicator Tube (MGIT), for antimicrobial susceptibility testing of Mycobacterium tuberculosis was evaluated on 78 clinical isolates. Rifampin (RMP), isoniazid (INH), streptomycin (SM), and ethambutol (EMB) were tested at the following concentrations: 1.0 μg/ml for RMP, 0.1 and 0.4 μg/ml for INH, 1.0 and 4.0 μg/ml for SM, and 5.0 and 7.5 μg/ml for EMB. Results were compared with those obtained by the BACTEC 460 TB radiometric system. Initially the reproducibility study showed 99.5% agreement on repeat testing with all the four drugs. With susceptibility testing of clinical isolates, excellent agreement between the two systems was found for all the drugs. A total of nine major errors were observed for only three isolates, resistant according to BACTEC MGIT 960 and susceptible according to BACTEC 460 TB, to SM (4.0 μg/ml), INH (0.1 μg/ml), and EMB (5.0 μg/ml) (one isolate) and to SM (1.0 μg/ml), INH (0.4 μg/ml), and EMB (5.0 μg/ml) (two isolates). When these isolates were tested by using the conventional proportion method on Löwenstein-Jensen medium, agreement with BACTEC MGIT 960 was found for five results and with BACTEC 460 TB for the remainder. The time to report results was 7.9 days by MGIT 960 and 7.3 days by BACTEC 460 TB, which was not found statistically significant (P > 0.05). In conclusion, the performance of BACTEC MGIT 960 was found similar to that of BACTEC 460 TB and this new system can be considered a good alternative to the radiometric method for routine susceptibility testing of M. tuberculosis. PMID:11724858

  4. 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.

  5. Antimicrobial susceptibility testing and genotypic characterization of Staphylococcus aureus from food and food animals.

    PubMed

    Wang, Xin; Meng, Jianghong; Zhou, Ting; Zhang, Yanming; Yang, Baowei; Xi, Meili; Sheng, Jinling; Zhi, Shuai; Xia, Xiaodong

    2012-02-01

    Staphylococcus aureus is commonly present in humans and animals. The aim of this study was to investigate antimicrobial resistance and genetic characteristics of S. aureus from food and food animals in Shaanxi Province in China. A total of 332 nasal swabs, breast skin swabs, raw milk, and pork samples were collected from local pig, dairy farms, or local grocery stores and screened for the presence of S. aureus. S. aureus isolates were characterized using antimicrobial susceptibility, pulsed-field gel electrophoresis (PFGE) analysis, and polymerase chain reaction for detecting pvl and mecA genes. Methicillin-resistant S. aureus (MRSA) strains were additionally tested for SCCmec type and exfoliative toxin genes. The prevalence of S. aureus was 30.6% in pig nasal swabs, 32.5% in pork, 25.7% in cow nasal swabs, 30.8% in cow breast skin swabs, and 29.3% in milk samples. Resistances were common among isolates tested against erythromycin (65.7%), tetracycline (65.7%), ciprofloxacin (52.7%), followed by gentamicin (36.7%), chloramphenicol (23.1%), cefoxitin (8.3%), and oxacillin (7.7%), but no isolate was resistant to vancomycin, amikacin, or cefoperazone. pvl gene was found in the isolates from all types of samples except from cow nasal swabs. Fourteen isolates from pig nasal swabs contained mecA gene and were considered as MRSA. PFGE analysis showed that nasal isolates differed from food isolates, but isolates from the same animal source appeared to cluster closely. The PFGE patterns of MRSA isolates were different from other S. aureus isolates from pig nasal cavity even though they were from the same source. All the MRSA isolates belonged to SCCmec type IV(b). No isolates contained exfoliative toxin genes. These findings indicated that S. aureus, including multidrug-resistant S. aureus, are widely spread in food animals and animal-derived foods in Shaanxi Province, China. MRSA isolates from pigs may pose potential health risks for workers in swine farms and the

  6. In vitro antimicrobial susceptibility testing of Helicobacter felis, H. bizzozeronii, and H. salomonis.

    PubMed

    Van den Bulck, K; Decostere, A; Gruntar, I; Baele, M; Krt, B; Ducatelle, R; Haesebrouck, F

    2005-07-01

    The susceptibilities of Helicobacter felis (15 strains), H. bizzozeronii (7 strains), and H. salomonis (3 strains) to 10 antimicrobial agents were investigated by determination of the MIC using the agar dilution method. No consistent differences were noticed between the different Helicobacter species, which were all highly susceptible to ampicillin, clarithromycin, tetracycline, tylosin, enrofloxacin, gentamicin, and neomycin, as demonstrated by low MICs. Higher MICs were obtained for lincomycin (up to 8 microg/ml) and spectinomycin (up to 4 microg/ml). Two H. felis strains showed a MIC of 16 microg/ml for metronidazole, suggesting acquired resistance to this antimicrobial agent.

  7. Multicenter evaluation of the new Vitek 2 yeast susceptibility test using new CLSI clinical breakpoints for fluconazole.

    PubMed

    Pfaller, M A; Diekema, D J; Procop, G W; Wiederhold, N P

    2014-06-01

    A fully automated antifungal susceptibility test system recently updated to reflect the new species-specific clinical breakpoints (CBPs) of fluconazole for Candida (Vitek 2 AF03 yeast susceptibility test; bioMérieux, Inc., Durham, NC) was compared in three different laboratories with the Clinical and Laboratory Standards Institute (CLSI) reference broth microdilution (BMD) method by testing 2 quality control strains, 10 reproducibility strains (4 Candida species and 6 Cryptococcus neoformans strains), and 746 isolates of Candida species (702 isolates, 13 species) and 44 isolates of C. neoformans against fluconazole. Excellent essential agreement (EA) (within 2 dilutions) between the reference and Vitek 2 MICs was observed for fluconazole and Candida species (94.0%). The EA was lower for fluconazole and C. neoformans at 86.4%. The mean times to a result with the Vitek 2 test were 9.1 h for Candida species and 12.1 h for C. neoformans. Categorical agreement (CA) between the two methods was assessed by using the new species-specific CBPs. For less common species without fluconazole CBPs, the epidemiological cutoff values (ECVs) were used to differentiate wild-type (WT; MIC, ≤ ECV) from non-WT (MIC, >ECV) strains. The CAs between the two methods were 92.0% for Candida species (0.3% very major errors [VME] and 2.6% major errors [ME]) and 84.1% for C. neoformans (4.5% VME and 11.4% ME). The updated Vitek 2 AF03 IUO yeast susceptibility system is comparable to the CLSI BMD reference method for testing the susceptibility of clinically important yeasts to fluconazole when using the new (lower) CBPs and ECVs.

  8. Comparative Evaluation of Disk Diffusion with Microdilution Assay in Susceptibility Testing of Caspofungin against Aspergillus and Fusarium Isolates

    PubMed Central

    Arikan, Sevtap; Paetznick, Victor; Rex, John H.

    2002-01-01

    We compared the disk diffusion and broth microdilution methods for susceptibility testing of caspofungin against Aspergillus (n = 78) and Fusarium (n = 22) isolates. Microdilution testing followed the NCCLS M-38P guidelines but was performed in antibiotic medium 3 supplemented to 2% glucose (AM3). Disk diffusion assays were performed on AM3 agar plates with a 2-μg caspofungin disk. By both methods, caspofungin showed favorable activity against Aspergillus isolates and no activity against Fusarium isolates. In the disk-based format, intrazonal growth that was not influenced by the drug concentration gradient was consistently observed for all of the Aspergillus isolates tested. PMID:12183278

  9. [In vitro drug susceptibility test of Plasmodium falciparum using a portable thermostat and CO2 gas generator].

    PubMed

    Lin, Q; Onda, T; Kano, S; Masuda, G; Suzuki, M

    1999-11-01

    We have recently developed a method of in vitro cultivation of P. falciparum using a portable incubator and AnaeroPack.CO2 (Onda et al.), we applied semi-microtechnique drug susceptibility tests to the culture method to evaluate the system using several P. falciparum strains or isolates of different susceptibilities to chloroquine (SGE-1, FCR-3, K-1, Patient 1 and 2). The new method gave comparable results to those shown by the standard test employing a modular incubator chamber with standard gas composition of 5% O2, 5% CO2 and 90% N2. Many useful data on the epidemiology of drug resistant malaria such as the emergence of multi-drug resistant isolates could be collected by applying this new method to the field survey.

  10. A Multilaboratory, Multicountry Study To Determine Bedaquiline MIC Quality Control Ranges for Phenotypic Drug Susceptibility Testing.

    PubMed

    Kaniga, Koné; Cirillo, Daniela M; Hoffner, Sven; Ismail, Nazir A; Kaur, Devinder; Lounis, Nacer; Metchock, Beverly; Pfyffer, Gaby E; Venter, Amour

    2016-12-01

    The aim of this study was to establish standardized drug susceptibility testing (DST) methodologies and reference MIC quality control (QC) ranges for bedaquiline, a diarylquinoline antimycobacterial, used in the treatment of adults with multidrug-resistant tuberculosis. Two tier-2 QC reproducibility studies of bedaquiline DST were conducted in eight laboratories using Clinical Laboratory and Standards Institute (CLSI) guidelines. Agar dilution and broth microdilution methods were evaluated. Mycobacterium tuberculosis H37Rv was used as the QC reference strain. Bedaquiline MIC frequency, mode, and geometric mean were calculated. When resulting data occurred outside predefined CLSI criteria, the entire laboratory data set was excluded. For the agar dilution MIC, a 4-dilution QC range (0.015 to 0.12 μg/ml) centered around the geometric mean included 95.8% (7H10 agar dilution; 204/213 observations with one data set excluded) or 95.9% (7H11 agar dilution; 232/242) of bedaquiline MICs. For the 7H9 broth microdilution MIC, a 3-dilution QC range (0.015 to 0.06 μg/ml) centered around the mode included 98.1% (207/211, with one data set excluded) of bedaquiline MICs. Microbiological equivalence was demonstrated for bedaquiline MICs determined using 7H10 agar and 7H11 agar but not for bedaquiline MICs determined using 7H9 broth and 7H10 agar or 7H9 broth and 7H11 agar. Bedaquiline DST methodologies and MIC QC ranges against the H37Rv M. tuberculosis reference strain have been established: 0.015 to 0.12 μg/ml for the 7H10 and 7H11 agar dilution MICs and 0.015 to 0.06 μg/ml for the 7H9 broth microdilution MIC. These methodologies and QC ranges will be submitted to CLSI and EUCAST to inform future research and provide guidance for routine clinical bedaquiline DST in laboratories worldwide.

  11. Infant Temperament, Parenting, and Externalizing Behavior in First Grade: A Test of the Differential Susceptibility Hypothesis

    ERIC Educational Resources Information Center

    Bradley, Robert H.; Corwyn, Robert F.

    2008-01-01

    Background: This study examines the differential susceptibility hypothesis as it pertains to relations between infant temperament, parenting, and behavior problems in first grade. Method: Data from the NICHD Study of Early Child Care were used in a series of hierarchical regression analyses focused on interactions between three aspects of…

  12. 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.

  13. Comparison of charcoal- and starch-based media for testing susceptibilities of Legionella species to macrolides, azalides, and fluoroquinolones.

    PubMed Central

    Pendland, S L; Martin, S J; Chen, C; Schreckenberger, P C; Danziger, L H

    1997-01-01

    We compared growth characteristics of 46 Legionella strains grown on buffered charcoal yeast extract alpha (BCYE alpha) agar and buffered starch yeast extract (BSYE) agar and MICs of macrolides, azalides, and fluoroquinolones for these organisms. Growth was poor and not reproducible on BSYE agar. Growth was excellent on BCYE alpha, and MICs were easy to interpret. BCYE alpha is superior to BSYE for testing susceptibilities of Legionella species by agar dilution. PMID:9350781

  14. Rapid Antimicrobial Susceptibility Testing of Bacillus anthracis, Yersinia pestis, and Burkholderia pseudomallei by Use of Laser Light Scattering Technology

    PubMed Central

    Lascols, Christine; Sue, David; Weigel, Linda M.

    2016-01-01

    Rapid methods to determine antimicrobial susceptibility would assist in the timely distribution of effective treatment or postexposure prophylaxis in the aftermath of the release of bacterial biothreat agents such as Bacillus anthracis, Yersinia pestis, or Burkholderia pseudomallei. Conventional susceptibility tests require 16 to 48 h of incubation, depending on the bacterial species. We evaluated a method that is based on laser light scattering technology that measures cell density in real time. We determined that it has the ability to rapidly differentiate between growth (resistant) and no growth (susceptible) of several bacterial threat agents in the presence of clinically relevant antimicrobials. Results were available in <4 h for B. anthracis and <6 h for Y. pestis and B. pseudomallei. One exception was B. pseudomallei in the presence of ceftazidime, which required >10 h of incubation. Use of laser scattering technology decreased the time required to determine antimicrobial susceptibility by 50% to 75% for B. anthracis, Y. pestis, and B. pseudomallei compared to conventional methods. PMID:26984973

  15. Turbine disc sealing assembly

    DOEpatents

    Diakunchak, Ihor S.

    2013-03-05

    A disc seal assembly for use in a turbine engine. The disc seal assembly includes a plurality of outwardly extending sealing flange members that define a plurality of fluid pockets. The sealing flange members define a labyrinth flow path therebetween to limit leakage between a hot gas path and a disc cavity in the turbine engine.

  16. Task 2 - Limits for High-Frequency Conducted Susceptibility Testing - CS114 (NRC-HQ-60-14-D-0015)

    SciTech Connect

    Wood, Richard Thomas; Ewing, Paul D.; Moses, Rebecca J.

    2015-09-01

    A principal focus of Task 2 under this project was for ORNL to evaluate the basis for susceptibility testing against high-frequency conducted interference and to establish recommendations to resolve concerns about the severity of test limits for the conducted susceptibility (CS) test, CS114, from MIL-STD-461. The primary concern about the test limit has been characterized by the EPRI EMI Working Group in the following terms: Demonstrating compliance with the CS114 test limits recommended in TR-102323 has proven to be problematic, even for components that have been tested to commercial standards and demonstrated proper operation in industrial applications [6]. Specifically, EPRI notes that the CS114 limits approved in regulatory documents are significantly higher than those invoked by the US military and similar commercial standards in the frequency range below 200 kHz. For this task, ORNL evaluated the original approach to establishing the test limit, EPRI technical findings from a review of the limit, and the regulatory basis through which the currently approved limits were accepted. Based on this analysis, strategies have been developed regarding changes to the CS114 limit that can resolve the technical concerns raised by the industry. Guided by the principles that reasonable assurance of safety must not be compromised but excessive conservatism should be reduced, recommendations on a suitable basis for a revised limit have been developed and can be incorporated into the planned Revision 2 of RG 1.180.

  17. Comparison of methods for antimicrobial susceptibility testing and MIC values for pleuromutilin drugs for Brachyspira hyodysenteriae isolated in Germany.

    PubMed

    Rohde, Judith; Kessler, Martina; Baums, Christoph G; Amtsberg, Gunter

    2004-08-19

    In Germany treatment of swine dysentery is hampered by Brachyspira hyodysenteriae strains showing elevated MIC values to the few antibiotics licensed. Therefore, susceptibility testing of clinical isolates is an important service to the swine practitioner. This study compares the established agar dilution procedure for antimicrobial susceptibility testing of this fastidious anaerobe to the broth microdilution test newly developed [Anim. Health Res. 2 (2001) 59; Vet. Microbiol. 84 (2002) 123; J. Clin. Microbiol. 41 (2003) 2596]. A total of 221 isolates were examined twice with either test procedure using tiamulin and valnemulin as antibiotics. Both methods gave reproducible results, and the MIC values for the reference strains B. hyodysenteriae B204 and Staphylococcus aureus ATCC 29213 corresponded to previously published data. However, the results for individual strains differed significantly for both tests (P < 0.001) with MIC values being on average one dilution step lower in the broth dilution method. The 221 strains used for comparing test procedures were isolated between 1989 and 2001. An additional 102 strains isolated in 2002 were tested only with the broth dilution procedure. A significant rise in the average MIC value for both pleuromutilins could be demonstrated when comparing earlier isolates to those from 2000 to 2001 (P < 0.05), while in 2002 the average MIC significantly decreased when compared to the value in 2000 (P < 0.05). However, strains with MIC values for tiamulin as high as 8 microg/ml (broth dilution) could still be isolated.

  18. Isolation, Identification, and In Vitro Antifungal Susceptibility Testing of Dermatophytes from Clinical Samples at Sohag University Hospital in Egypt

    PubMed Central

    Shalaby, Mona Fattouh Mohamed; El-din, Asmaa Nasr; El-Hamd, Mohammed Abu

    2016-01-01

    Aim The objective of this study was to isolate, identify, and explore the in-vitro antifungal susceptibility pattern of dermatophytes isolated from clinically suspected cases of dermatophytosis (tinea infections) attending the Dermatology Outpatient Clinic. Methods This study was conducted at Sohag University Hospital from December 2014 to December 2015. Clinical samples (e.g., skin scrapings and hair stumps) were collected under aseptic precautions. The identification of dermatophytes was performed through microscopic examination using 10% potassium hydroxide (KOH) with 40% dimethyl sulphoxide (DMSO) mounts and culture on Sabouraud dextrose agar (SDA) and on Dermasel agar base media, both supplemented with chloramphenicol and cycloheximide. All dermatophytes isolates were subjected to antifungal susceptibility testing using the agar-based disk diffusion (ABDD) method against Clotrimazole, Miconazole, Fluconazole, and Griseofulvin. Data were analyzed via SPSS 16, using Chi square and a screening test (cross-tabulation method). Results A total of 110 patients of dermatophytosis were studied. The patients were clinically diagnosed and mycologically confirmed as having tinea capitis (49), tinea corporis (30), tinea pedis (16), tinea cruris (9), or tinea barbae (6). The dermatophytes isolates belonged to 4 species: Microsporum canis 58 (52.7%), Microsporum gypseum 23 (20.9%), Trichophyton mentagrophytes 18 (16.4%), and Microsporum audouinii 11 (10%). The most effective antifungal drugs tested were Clotrimazole, followed by Miconazole (95.5% and 84.5% of isolates were susceptible, respectively). Conclusion Every patient with a tinea infection should be properly studied for a mycological examination and should be treated accordingly. Dermasel agar is more useful as an identification medium in the isolation of dermatophytes. The ABDD method appears to be a simple, cost-effective, and promising method for the evaluation of antifungal susceptibility of dermatophytes. PMID

  19. Testing the burden of rare variation in arrhythmia-susceptibility genes provides new insights into molecular diagnosis for Brugada syndrome.

    PubMed

    Le Scouarnec, Solena; Karakachoff, Matilde; Gourraud, Jean-Baptiste; Lindenbaum, Pierre; Bonnaud, Stéphanie; Portero, Vincent; Duboscq-Bidot, Laëtitia; Daumy, Xavier; Simonet, Floriane; Teusan, Raluca; Baron, Estelle; Violleau, Jade; Persyn, Elodie; Bellanger, Lise; Barc, Julien; Chatel, Stéphanie; Martins, Raphaël; Mabo, Philippe; Sacher, Frédéric; Haïssaguerre, Michel; Kyndt, Florence; Schmitt, Sébastien; Bézieau, Stéphane; Le Marec, Hervé; Dina, Christian; Schott, Jean-Jacques; Probst, Vincent; Redon, Richard

    2015-05-15

    The Brugada syndrome (BrS) is a rare heritable cardiac arrhythmia disorder associated with ventricular fibrillation and sudden cardiac death. Mutations in the SCN5A gene have been causally related to BrS in 20-30% of cases. Twenty other genes have been described as involved in BrS, but their overall contribution to disease prevalence is still unclear. This study aims to estimate the burden of rare coding variation in arrhythmia-susceptibility genes among a large group of patients with BrS. We have developed a custom kit to capture and sequence the coding regions of 45 previously reported arrhythmia-susceptibility genes and applied this kit to 167 index cases presenting with a Brugada pattern on the electrocardiogram as well as 167 individuals aged over 65-year old and showing no history of cardiac arrhythmia. By applying burden tests, a significant enrichment in rare coding variation (with a minor allele frequency below 0.1%) was observed only for SCN5A, with rare coding variants carried by 20.4% of cases with BrS versus 2.4% of control individuals (P = 1.4 × 10(-7)). No significant enrichment was observed for any other arrhythmia-susceptibility gene, including SCN10A and CACNA1C. These results indicate that, except for SCN5A, rare coding variation in previously reported arrhythmia-susceptibility genes do not contribute significantly to the occurrence of BrS in a population with European ancestry. Extreme caution should thus be taken when interpreting genetic variation in molecular diagnostic setting, since rare coding variants were observed in a similar extent among cases versus controls, for most previously reported BrS-susceptibility genes.

  20. Pyrazinamide susceptibility testing of Mycobacterium tuberculosis by high resolution melt analysis.

    PubMed

    Pholwat, Suporn; Stroup, Suzanne; Gratz, Jean; Trangan, Varittha; Foongladda, Suporn; Kumburu, Happiness; Juma, Saumu Pazia; Kibiki, Gibson; Houpt, Eric

    2014-01-01

    Pyrazinamide (PZA) plays the important role in shortening the tuberculosis treatment period and in treating MDR-TB. Phenotypic PZA susceptibility methods are limited because they require specialized acidified media, which increases costs and complexity. In this study we developed a genotypic high resolution melt (HRM) analysis technique to detect pncA mutations associated with PZA resistant Mycobacterium tuberculosis. Seven overlapping primer pairs were designed to cover the entire pncA gene and upstream regions. Each gene segment was individually amplified by real-time PCR followed by HRM analysis. The assay was evaluated on 98 clinical M. tuberculosis isolates (41 PZA susceptible by MGIT method, 55 PZA resistant, 2 undetermined). HRM was 94% concordant to full-length sequencing results, with most discrepancies attributable to mixed populations per HRM or transversions. Sequencing and HRM yielded 82% and 84% concordance, respectively, to phenotypic PZA susceptibilities by MGIT, with most discrepancies attributable to isolates with wild-type pncA but phenotypic PZA resistance. This HRM technique is a simple and high-throughput method for screening clinical M. tuberculosis samples for PZA resistance.

  1. Resazurin Microtiter Assay Plate Testing of Mycobacterium tuberculosis Susceptibilities to Second-Line Drugs: Rapid, Simple, and Inexpensive Method

    PubMed Central

    Martin, Anandi; Camacho, Mirtha; Portaels, Françoise; Palomino, Juan Carlos

    2003-01-01

    The emergence of multidrug-resistant tuberculosis calls for new, rapid drug susceptibility tests. We have tested 150 Mycobacterium tuberculosis isolates against the second-line drugs ethionamide, kanamycin, capreomycin, ofloxacin, and para-aminosalicylic acid by the colorimetric resazurin microtiter assay and the proportion method. By visual reading, MICs were obtained after 8 days. A very good correlation between results by the colorimetric resazurin microtiter assay and the proportion method was obtained. The colorimetric resazurin microtiter assay is inexpensive, rapid, and simple to perform, and implementation of the assay is feasible for low-resource countries. PMID:14576129

  2. In vitro susceptibility testing of dermatophytes isolated in Goiania, Brazil, against five antifungal agents by broth microdilution method.

    PubMed

    Araújo, Crystiane Rodrigues; Miranda, Karla Carvalho; Fernandes, Orionalda de Fatima Lisboa; Soares, Ailton José; Silva, Maria do Rosário Rodrigues

    2009-01-01

    The antifungal activities of fluconazole, itraconazole, ketoconazole, terbinafine and griseofulvin were tested by broth microdilution technique, against 60 dermatophytes isolated from nail or skin specimens from Goiania city patients, Brazil. In this study, the microtiter plates were incubated at 28 masculineC allowing a reading of the minimal inhibitory concentration (MIC) after four days of incubation for Trichophyton mentagrophytes and five days for T. rubrum and Microsporum canis. Most of the dermatophytes had uniform patterns of susceptibility to the antifungal agents tested. Low MIC values as 0.03 microg/mL were found for 33.3%, 31.6% and 15% of isolates for itraconazole, ketoconazole and terbinafine, respectively.

  3. Assessment of a 96-Well Plate Assay of Quantitative Drug Susceptibility Testing for Mycobacterium Tuberculosis Complex in China

    PubMed Central

    Xia, Hui; Zheng, Yang; Zhao, Bing; van den Hof, Susan; Cobelens, Frank; Zhao, YanLin

    2017-01-01

    Objective To evaluate the performance of the Sensitire MYCOTB MIC Plate (MYCOTB) which could measure the twelve anti-tuberculosis drugs susceptibility on one 96-wells plate. Methods A total of 140 MDR-TB strains and 60 non-MDR strains were sub-cultured and 193 strains were finally tested for drug resistance using MYCOTB and agar proportion method (APM) and another 7 strains failed of subculture. The drugs included ofloxacin (Ofx), moxifloxacin (Mfx), rifampin (RFP), amikacin (Am), rifabutin (Rfb), para-aminosalicylic acid (PAS), ethionamide (Eth), isoniazid (INH), kanamycin (Km), ethambutol (EMB), streptomycin (Sm), and cycloserine(Cs). The categorical agreement, conditional agreement, sensitivity and specificity of MYCOTB were assessed in comparison with APM. For strains with inconsistent results between MYCOTB and APM, the drug resistance related gene fragments were amplified and sequenced: gyrA for Ofx and Mfx; rpoB for RFP and Rfb; embB for EMB; rpsl for Sm; katG and the promoter region of inhA for INH, ethA and the promoter region of inhA for Eth. The sequence results were compared with results of MYCOTB and APM to analyze the consistency between sequence results and MYCOTB or APM. Results The categorical agreement between two methods for each drug ranged from 88.6% to 100%. It was the lowest for INH (88.6%). The sensitivity and specificity of MYCOTB ranged from 71.4% to 100% and 84.3% to 100%, respectively. The sensitivity was lowest for Cs(71.4%), EMB at 10μg/ml (80.0%) and INH at 10.0μg/ml (84.6%). The specificity was lowest for Rfb (84.3%). Overall discordance between the two phenotypic methods was observed for 96 strains, of which 63 (65.6%) were found susceptible with APM and resistant with MYCOTB and the remaining 33(34.4%) strains were resistant by APM and susceptible with MYCOTB. 34/52 (65.4%) sequenced APM susceptible and MYCOTB resistant(APM-S/MYCOTB-R) strains had mutations or insertions in the amplified regions. 20/30 (66.7%) sequenced APM

  4. 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

  5. Frequent major errors in antimicrobial susceptibility testing of bacterial strains distributed under the Deutsches Krebsforschungszentrum Quality Assurance Program.

    PubMed

    Boot, R

    2012-07-01

    The Quality Assurance Program (QAP) of the Deutsches Krebsforschungszentrum (DKFZ) was a proficiency testing system developed to service the laboratory animal discipline. The QAP comprised the distribution of bacterial strains from various species of animals for identification to species level and antibiotic susceptibility testing (AST). Identification capabilities were below acceptable standards. This study evaluated AST results using the DKFZ compilations of test results for all bacterial strains showing the number of participants reporting the strain as resistant (R), sensitive (S) or intermediate susceptible (I) to each antibiotic substance used. Due to lack of information about methods used, it was assumed that what the majority of the participants reported (R or S) was the correct test result and that an opposite result was a major error (ME). MEs occurred in 1375 of 14,258 (9.7%) of test results and ME% ranged from 0% to 23.2% per bacterial group-agent group combination. Considerable variation in MEs was found within groups of bacteria and within groups of agents. In addition to poor performance in proper species classification, the quality of AST in laboratory animal diagnostic laboratories seems far below standards considered acceptable in human diagnostic microbiology.

  6. Development and testing of method for assessing and mapping agricultural areas susceptible to atrazine leaching in the state of Washington

    USGS Publications Warehouse

    Voss, Frank D.

    2003-01-01

    In a joint effort by the Washington State Department of Agriculture, the Washington Department of Ecology, and the U.S. Geological Survey, the Environmental Protection Agency's Pesticide Root Zone Model and a Geographic Information System were used to develop and test a method for screening and mapping the susceptibility of ground water in agricultural areas to pesticide contamination. The objective was to produce a map that would be used by the Washington State Department of Agriculture to allocate resources for monitoring pesticide levels in ground water. The method was tested by producing a map showing susceptibility to leaching of the pesticide atrazine for the Columbia Basin Irrigation Project, which encompasses an area of intensive agriculture in eastern Washington. The reliability of the atrazine map was assessed by using statistical procedures to determine whether the median of the percentage of atrazine simulated to leach below the root zone in wells where atrazine was detected was statistically greater than the median percentage at wells where atrazine was not detected (at or above 0.001 microgram per liter) in 134 wells sampled by the U.S. Geological Survey. A statistical difference in medians was not found when all 134 wells were compared. However, a statistical difference was found in medians for two subsets of the 134 wells that were used in land-use studies (studies examining the quality of ground water beneath specific crops). The statistical results from wells from the land-use studies indicate that the model potentially can be used to map the relative susceptibility of agricultural areas to atrazine leaching. However, the distinction between areas of high and low susceptibility may not yet be sufficient to use the method for allocating resources to monitor water quality. Several options are offered for improving the reliability of future simulations.

  7. Bacterial antibiotic resistance studies using in vitro dynamic models: Population analysis vs. susceptibility testing as endpoints of mutant enrichment.

    PubMed

    Firsov, Alexander A; Strukova, Elena N; Portnoy, Yury A; Shlykova, Darya S; Zinner, Stephen H

    2015-09-01

    Emergence of bacterial antibiotic resistance is usually characterised either by population analysis or susceptibility testing. To compare these endpoints in their ability to demonstrate clear relationships with the ratio of 24-h area under the concentration-time curve (AUC24) to the minimum inhibitory concentration (MIC), enrichment of ciprofloxacin-resistant mutants of four clinical isolates of Pseudomonas aeruginosa was studied in an in vitro dynamic model that simulates mono-exponential pharmacokinetics of ciprofloxacin over a wide range of the AUC24/MIC ratios. Each organism was exposed to twice-daily ciprofloxacin for 3 days. Amplification of resistant mutants was monitored by plating on media with 2×, 4×, 8× and 16× MIC of ciprofloxacin. Population analysis data were expressed by the area under the bacterial mutant concentration-time curve (AUBCM). Changes in P. aeruginosa susceptibility were examined by daily MIC determinations. To account for the different susceptibilities of P. aeruginosa strains, post-exposure MICs (MICfinal) were related to the MICs determined with the starting inoculum (MICinitial). For each organism, AUC24/MIC relationships both with AUBCM and MICfinal/MICinitial were bell-shaped, but the latter were more strain-specific than the former. Using combined data on all four isolates, AUBCM showed a better correlation than MICfinal/MICinitial (r(2)=0.75 vs. r(2)=0.53). The shift of MICfinal/MICinitial relative to AUBCM vs. AUC24/MIC curves resulted in a weak correlation between AUBCM and MICfinal/MICinitial (r(2)=0.41). These data suggest that population analysis is preferable to susceptibility testing in bacterial resistance studies and that these endpoints should not be considered interchangeable.

  8. 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.

  9. The inner cavity of the circumnuclear disc

    NASA Astrophysics Data System (ADS)

    Blank, M.; Morris, M. R.; Frank, A.; Carroll-Nellenback, J. J.; Duschl, W. J.

    2016-06-01

    The circumnuclear disc (CND) orbiting the Galaxy's central black hole is a reservoir of material that can ultimately provide energy through accretion, or form stars in the presence of the black hole, as evidenced by the stellar cluster that is presently located at the CND's centre. In this paper, we report the results of a computational study of the dynamics of the CND. The results lead us to question two paradigms that are prevalent in previous research on the Galactic Centre. The first is that the disc's inner cavity is maintained by the interaction of the central stellar cluster's strong winds with the disc's inner rim, and secondly, that the presence of unstable clumps in the disc implies that the CND is a transient feature. Our simulations show that, in the absence of a magnetic field, the interaction of the wind with the inner disc rim actually leads to a filling of the inner cavity within a few orbital time-scales, contrary to previous expectations. However, including the effects of magnetic fields stabilizes the inner disc rim against rapid inward migration. Furthermore, this interaction causes instabilities that continuously create clumps that are individually unstable against tidal shearing. Thus the occurrence of such unstable clumps does not necessarily mean that the disc is itself a transient phenomenon. The next steps in this investigation are to explore the effect of the magnetorotational instability on the disc evolution and to test whether the results presented here persist for longer time-scales than those considered here.

  10. Rapid and accurate direct antibiotic susceptibility testing of blood culture broths using MALDI Sepsityper combined with the BD Phoenix automated system.

    PubMed

    Hazelton, Briony; Thomas, Lee C; Olma, Thomas; Kok, Jen; O'Sullivan, Matthew; Chen, Sharon C-A; Iredell, Jonathan R

    2014-12-01

    Antibiotic susceptibility testing with the BD Phoenix system on bacterial cell pellets generated from blood culture broths using the Bruker MALDI Sepsityper kit was evaluated. Seventy-six Gram-negative isolates, including 12 with defined multi-resistant phenotypes, had antibiotic susceptibility testing (AST) performed by Phoenix on the cell pellet in parallel with conventional methods. In total, 1414/1444 (97.9 %) of susceptibility tests were concordant, with only 1 (0.07 %) very major error. This novel method has the potential to reduce the turnaround time for AST results by up to a day for Gram-negative bacteraemias.

  11. Minimal attachment killing (MAK): a versatile method for susceptibility testing of attached biofilm-positive and -negative Staphylococcus epidermidis.

    PubMed

    Knobloch, Johannes K-M; Von Osten, Heimke; Horstkotte, Matthias A; Rohde, Holger; Mack, Dietrich

    2002-10-01

    Due to its ability to attach to polymeric surfaces Staphylococcus epidermidis is a common pathogen in chronic, medical device-associated infections. Attached S. epidermidis displays reduced susceptibility against a variety of antimicrobial substances, and little correlation between standard susceptibility test results and clinical outcome of antibiotic treatment is observed. In this study we established a new, versatile, and easy method of antimicrobial susceptibility testing for attached Staphylococcus epidermidis, suitable for both biofilm-negative and biofilm-positive attached bacteria using readily available equipment. For three biofilm-positive wild-type strains and their biofilm-negative mutants minimal attachment killing concentrations (MAK) of penicillin, oxacillin, vancomycin, and gentamicin were determined. Depending on strain and investigated antibiotics, a heterogeneous MAK (MAK(hetero)) could be differentiated from a homogeneous resistance (MAK(homo)), favoring a model of few persisters within attached cells under antibiotic treatment. For the biofilm-negative mutants, a lower MAK(homo) was detected than for the corresponding wild types for some of the tested antibiotics, which probably resulted from higher bacterial inocula of wild-type strains, whereas the MAK(hetero) were comparable for mutants and wild types for most of the tested antibiotics and strains. These data indicate that biofilm formation is not a necessary prerequisite for persistence of attached S. epidermidis cells under antibiotic treatment, which could explain therapeutic failure in foreign body-associated infections due to biofilm-negative S. epidermidis isolates. The highly individual resistance phenotypes of the investigated strains with different antibiotics suggests that MAK determination could help to predict the therapeutic outcome of foreign body-associated infections with both biofilm-positive and biofilm-negative S. epidermidis.

  12. Rapid antimicrobial susceptibility test for identification of new therapeutics and drug combinations against multidrug-resistant bacteria

    PubMed Central

    Sun, Wei; Weingarten, Rebecca A; Xu, Miao; Southall, Noel; Dai, Sheng; Shinn, Paul; Sanderson, Philip E; Williamson, Peter R; Frank, Karen M; Zheng, Wei

    2016-01-01

    Current antimicrobial susceptibility testing has limited screening capability for identifying empirical antibiotic combinations to treat severe bacterial infections with multidrug-resistant (MDR) organisms. We developed a new antimicrobial susceptibility assay using automated ultra-high-throughput screen technology in combination with a simple bacterial growth assay. A rapid screening of 5170 approved drugs and other compounds identified 25 compounds with activities against MDR Klebsiella pneumoniae. To further improve the efficacy and reduce the effective drug concentrations, we applied a targeted drug combination approach that integrates drugs' clinical antimicrobial susceptibility breakpoints, achievable plasma concentrations, clinical toxicities and mechanisms of action to identify optimal drug combinations. Three sets of three-drug combinations were identified with broad-spectrum activities against 10 MDR clinical isolates including K. pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, Citrobacter freundii, Enterobacter cloacae and Escherichia coli. Colistin–auranofin–ceftazidime and colistin–auranofin–rifabutin suppressed >80% growth of all 10 MDR strains; while rifabutin–colistin–imipenem inhibited >75% of these strains except two Acinetobacter baumannii isolates. The results demonstrate this new assay has potential as a real-time method to identify new drugs and effective drug combinations to combat severe clinical infections with MDR organisms. PMID:27826141

  13. Rapid antimicrobial susceptibility test for identification of new therapeutics and drug combinations against multidrug-resistant bacteria.

    PubMed

    Sun, Wei; Weingarten, Rebecca A; Xu, Miao; Southall, Noel; Dai, Sheng; Shinn, Paul; Sanderson, Philip E; Williamson, Peter R; Frank, Karen M; Zheng, Wei

    2016-11-09

    Current antimicrobial susceptibility testing has limited screening capability for identifying empirical antibiotic combinations to treat severe bacterial infections with multidrug-resistant (MDR) organisms. We developed a new antimicrobial susceptibility assay using automated ultra-high-throughput screen technology in combination with a simple bacterial growth assay. A rapid screening of 5170 approved drugs and other compounds identified 25 compounds with activities against MDR Klebsiella pneumoniae. To further improve the efficacy and reduce the effective drug concentrations, we applied a targeted drug combination approach that integrates drugs' clinical antimicrobial susceptibility breakpoints, achievable plasma concentrations, clinical toxicities and mechanisms of action to identify optimal drug combinations. Three sets of three-drug combinations were identified with broad-spectrum activities against 10 MDR clinical isolates including K. pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, Citrobacter freundii, Enterobacter cloacae and Escherichia coli. Colistin-auranofin-ceftazidime and colistin-auranofin-rifabutin suppressed >80% growth of all 10 MDR strains; while rifabutin-colistin-imipenem inhibited >75% of these strains except two Acinetobacter baumannii isolates. The results demonstrate this new assay has potential as a real-time method to identify new drugs and effective drug combinations to combat severe clinical infections with MDR organisms.

  14. Rapid drug susceptibility test of Mycobacterium tuberculosis using microscopic time-lapse imaging in an agarose matrix.

    PubMed

    Choi, Jungil; Yoo, Jungheon; Kim, Ki-Jung; Kim, Eun-Geun; Park, Kyung Ock; Kim, Hyejin; Kim, Haeun; Jung, Hyunju; Kim, Taeyoung; Choi, Myungjin; Kim, Hee Chan; Ryoo, Sungweon; Jung, Yong-Gyun; Kwon, Sunghoon

    2016-03-01

    Tuberculosis (TB) is a major global health problem, and multi-drug-resistant TB (MDR-TB) and extensively drug-resistant TB (XDR-TB) are spreading throughout the world. However, conventional drug susceptibility test (DST) methods, which rely on the detection of the colony formation on a solid medium, require 1-2 months to the result. A rapid and accurate DST is necessary to identify patients with drug-resistant TB and treat them with appropriate drugs. Here, we used microscopic imaging of Mycobacterium tuberculosis (MTB) immobilized in an agarose matrix for a rapid DST. The agarose matrix, which was molded in a microfluidic chip, was inoculated with MTB, and TB drugs in liquid culture medium diffused throughout the agarose to reach the MTB immobilized in the agarose matrix. After the responses of MTB to drugs were tracked with an automated microscopic system, an image-processing program automatically determined the susceptibility and resistance of MTB to specific doses of TB drugs. The automatic DST system was able to assess the drug susceptibility of various drug-resistant clinical TB strains within 9 days with an accuracy comparable to that of conventional method. Our rapid DST method based on microscopic time-lapse imaging greatly reduces the time required for a DST and can be used to rapidly and accurately treat TB patients.

  15. Adolescent behavioral and neural reward sensitivity: a test of the differential susceptibility theory

    PubMed Central

    Richards, J S; Arias Vásquez, A; von Rhein, D; van der Meer, D; Franke, B; Hoekstra, P J; Heslenfeld, D J; Oosterlaan, J; Faraone, S V; Buitelaar, J K; Hartman, C A

    2016-01-01

    Little is known about the causes of individual differences in reward sensitivity. We investigated gene–environment interactions (GxE) on behavioral and neural measures of reward sensitivity, in light of the differential susceptibility theory. This theory states that individuals carrying plasticity gene variants will be more disadvantaged in negative, but more advantaged in positive environments. Reward responses were assessed during a monetary incentive delay task in 178 participants with and 265 without attention-deficit/hyperactivity disorder (ADHD), from N=261 families. We examined interactions between variants in candidate plasticity genes (DAT1, 5-HTT and DRD4) and social environments (maternal expressed emotion and peer affiliation). HTTLPR short allele carriers showed the least reward speeding when exposed to high positive peer affiliation, but the most when faced with low positive peer affiliation or low maternal warmth. DAT1 10-repeat homozygotes displayed similar GxE patterns toward maternal warmth on general task performance. At the neural level, DRD4 7-repeat carriers showed the least striatal activation during reward anticipation when exposed to high maternal warmth, but the most when exposed to low warmth. Findings were independent of ADHD severity. Our results partially confirm the differential susceptibility theory and indicate the importance of positive social environments in reward sensitivity and general task performance for persons with specific genotypes. PMID:27045841

  16. Adolescent behavioral and neural reward sensitivity: a test of the differential susceptibility theory.

    PubMed

    Richards, J S; Arias Vásquez, A; von Rhein, D; van der Meer, D; Franke, B; Hoekstra, P J; Heslenfeld, D J; Oosterlaan, J; Faraone, S V; Buitelaar, J K; Hartman, C A

    2016-04-05

    Little is known about the causes of individual differences in reward sensitivity. We investigated gene-environment interactions (GxE) on behavioral and neural measures of reward sensitivity, in light of the differential susceptibility theory. This theory states that individuals carrying plasticity gene variants will be more disadvantaged in negative, but more advantaged in positive environments. Reward responses were assessed during a monetary incentive delay task in 178 participants with and 265 without attention-deficit/hyperactivity disorder (ADHD), from N=261 families. We examined interactions between variants in candidate plasticity genes (DAT1, 5-HTT and DRD4) and social environments (maternal expressed emotion and peer affiliation). HTTLPR short allele carriers showed the least reward speeding when exposed to high positive peer affiliation, but the most when faced with low positive peer affiliation or low maternal warmth. DAT1 10-repeat homozygotes displayed similar GxE patterns toward maternal warmth on general task performance. At the neural level, DRD4 7-repeat carriers showed the least striatal activation during reward anticipation when exposed to high maternal warmth, but the most when exposed to low warmth. Findings were independent of ADHD severity. Our results partially confirm the differential susceptibility theory and indicate the importance of positive social environments in reward sensitivity and general task performance for persons with specific genotypes.

  17. Rapid Identification and Multiple Susceptibility Testing of Pathogens from Positive-Culture Sterile Body Fluids by a Combined MALDI-TOF Mass Spectrometry and Vitek Susceptibility System

    PubMed Central

    Tian, Yueru; Zheng, Bing; Wang, Bei; Lin, Yong; Li, Min

    2016-01-01

    Infections of the bloodstream, central nervous system, peritoneum, joints, and other sterile areas are associated with high morbidity and sequelae risk. Timely initiation of effective antimicrobial therapy is crucial to improving patient prognosis. However, standard final identification and antimicrobial susceptibility tests (ASTs) are reported 16–48 h after a positive alert. For a rapid, effective and low-cost diagnosis, we combined matrix-assisted laser desorption/ionization time of flight mass spectrometry with a Vitek AST system, and performed rapid microbial identification (RMI) and rapid multiple AST (RMAST) on non-duplicated positive body fluid cultures collected from a hospital in Shanghai, China. Sterile body fluid positive culture and blood positive culture caused by Gram negative (GN) or polymicrobial were applied to the MALDI–TOF measurement directly. When positive blood culture caused by Gram positive (GP) bacteria or yeasts, they were resuspended in 1 ml brain heart infusion for 2 or 4 h enrichment, respectively. Regardless of enrichment, the RMI (completed in 40 min per sample) accurately identified GN and GP bacteria (98.9 and 87.2%, respectively), fungi (75.7%), and anaerobes (94.7%). Dominant species in multiple cultures and bacteria that failed to grow on the routing plates were correctly identified in 81.2 and 100% of cases, respectively. The category agreements of RMAST results, determined in the presence of various antibiotics, were similarly to previous studies. The RMI and RMAST results not only reduce the turnaround time of the patient report by 18–36 h, but also indicate whether a patient's antibiotic treatment should be accelerated, ceased or de-escalated, and adjusted the essential drugs modification for an optimized therapy. PMID:27148212

  18. Multicenter Comparison of the Etest and EUCAST Methods for Antifungal Susceptibility Testing of Candida Isolates to Micafungin

    PubMed Central

    Bougnoux, M.-E.; Accoceberry, I.; Angoulvant, A.; Bailly, E.; Botterel, F.; Chevrier, S.; Chouaki, T.; Dalle, F.; Datry, A.; Dupuis, A.; Fekkar, A.; Gangneux, J. P.; Guitard, J.; Hennequin, C.; Le Govic, Y.; Le Pape, P.; Maubon, D.; Sautour, M.; Sendid, B.; Chandenier, J.

    2016-01-01

    In vitro susceptibility of 933 Candida isolates, from 16 French hospitals, to micafungin was determined using the Etest in each center. All isolates were then sent to a single center for determination of MICs by the EUCAST reference method. Overall essential agreement between the two tests was 98.5% at ±2 log2 dilutions and 90.2% at ±1 log2 dilutions. Categorical agreement was 98.2%. The Etest is a valuable alternative to EUCAST for the routine determination of micafungin MICs in medical mycology laboratories. PMID:27297480

  19. Multicenter Comparison of the Etest and EUCAST Methods for Antifungal Susceptibility Testing of Candida Isolates to Micafungin.

    PubMed

    Bougnoux, M-E; Dannaoui, E; Accoceberry, I; Angoulvant, A; Bailly, E; Botterel, F; Chevrier, S; Chouaki, T; Cornet, M; Dalle, F; Datry, A; Dupuis, A; Fekkar, A; Gangneux, J P; Guitard, J; Hennequin, C; Le Govic, Y; Le Pape, P; Maubon, D; Ranque, S; Sautour, M; Sendid, B; Chandenier, J

    2016-08-01

    In vitro susceptibility of 933 Candida isolates, from 16 French hospitals, to micafungin was determined using the Etest in each center. All isolates were then sent to a single center for determination of MICs by the EUCAST reference method. Overall essential agreement between the two tests was 98.5% at ±2 log2 dilutions and 90.2% at ±1 log2 dilutions. Categorical agreement was 98.2%. The Etest is a valuable alternative to EUCAST for the routine determination of micafungin MICs in medical mycology laboratories.

  20. Comparison of TaqMan® Array Card and MYCOTB™ with conventional phenotypic susceptibility testing in MDR-TB

    PubMed Central

    Foongladda, S.; Banu, S.; Pholwat, S.; Gratz, J.; O-Thong, S.; Nakkerd, N.; Chinli, R.; Ferdous, S. S.; Rahman, S. M. M.; Rahman, A.; Ahmed, S.; Heysell, S.; Sariko, M.; Kibiki, G.

    2016-01-01

    SUMMARY BACKGROUND: Although phenotypic drug susceptibility testing (DST) is endorsed as the standard for second-line drug testing of Mycobacterium tuberculosis, it is slow and laborious. METHODS: We evaluated the accuracy of two faster, easier methodologies that provide results for multiple drugs: a genotypic TaqMan® Array Card (TAC) and the Sensititre® MYCOTB™ plate. Both methods were tested at three central laboratories in Bangladesh, Tanzania, and Thailand with 212 multidrug-resistant tuberculosis (MDR-TB) isolates and compared with the laboratories' phenotypic method in use. RESULTS: The overall accuracy for ethambutol, streptomycin, amikacin, kanamycin, ofloxacin, and moxifloxacin vs. the phenotypic standard was 87% for TAC (range 70–99) and 88% for the MYCOTB plate (range 76–98). To adjudicate discordances, we re-defined the standard as the consensus of the three methods, against which the TAC and MYCOTB plate yielded 94–95% accuracy, while the phenotypic result yielded 93%. Some isolates with genotypic mutations and high minimum inhibitory concentration (MIC) were phenotypically susceptible, and some isolates without mutations and low MIC were phenotypically resistant, questioning the phenotypic standard. CONCLUSIONS: In our view, the TAC, the MYCOTB plate, and the conventional phenotypic method have similar performance for second-line drugs; however, the former methods offer speed, throughput, and quantitative DST information. PMID:27393547

  1. [Consensus for antimicrobial susceptibility testing for Enterobacteriaceae. Subcommittee on Antimicrobials, SADEBAC (Argentinian Society of Clinical Bacteriology), Argentinian Association of Microbiology].

    PubMed

    Famiglietti, A; Quinteros, M; Vázquez, M; Marín, M; Nicola, F; Radice, M; Galas, M; Pasterán, F; Bantar, C; Casellas, J M; Kovensky Pupko, J; Couto, E; Goldberg, M; Lopardo, H; Gutkind, G; Soloaga, R

    2005-01-01

    Taking into account previous recommendations from the National Committee for Clinical Laboratory Standards (NCCLS), the Antimicrobial Committee, Sociedad Argentina de Bacteriología Clínica (SADEBAC), Asociación Argentina de Microbiología (AAM), and the experience from its members and some invited microbiologists, a consensus was obtained for antimicrobial susceptibility testing and interpretation in most frequent enterobacterial species isolated from clinical samples in our region. This document describes the natural antimicrobial resistance of some Enterobacteriaceae family members, including the resistance profiles due to their own chromosomal encoded beta-lactamases. A list of the antimicrobial agents that should be tested, their position on the agar plates, in order to detect the most frequent antimicrobial resistance mechanisms, and considerations on which antimicrobial agents should be reported regarding to the infection site and patient characteristics are included. Also, a description on appropriate phenotypic screening and confirmatory test for detection of prevalent extended spectrum beta-lactamases in our region are presented. Finally, a summary on frequent antimicrobial susceptibility profiles and their probably associated resistance mechanisms, and some infrequent antimicrobial resistance profiles that deserve confirmation are outlined.

  2. Rapid susceptibility testing of Mycobacterium avium complex and Mycobacterium tuberculosis isolated from AIDS patients

    NASA Technical Reports Server (NTRS)

    Dhople, Arvind M.

    1994-01-01

    In ominous projections issued by both U.S. Public Health Service and the World Health Organization, the epidemic of HIV infection will continue to rise more rapidly worldwide than predicted earlier. The AIDS patients are susceptible to diseases called opportunistic infections of which tuberculosis and Mycobacterium avium complex (MAC) infection are most common. This has created an urgent need to uncover new drugs for the treatment of these infections. In the seventies, NASA scientists at Goddard Space Flight Center, Greenbelt, MD, had adopted a biochemical indicator, adenosine triphosphate (ATP), to detect presence of life in extraterrestrial space. We proposed to develop ATP assay technique to determine sensitivity of antibacterial compounds against MAC and M. tuberculosis.

  3. Fast test for assessing the susceptibility of Mycobacterium tuberculosis to isoniazid and rifampin by real-time PCR

    PubMed Central

    Gonçalves, Maria Gisele; Fukasawa, Lucila Okuyama; Oliveira, Rosangela Siqueira; Salgado, Maristela Marques; Harrison, Lee H; Shutt, Kathleen A; Sacchi, Claudio Tavares

    2015-01-01

    Mycobacterium tuberculosis is the bacterium that causes tuberculosis (TB), a leading cause of death from infectious disease worldwide. Rapid diagnosis of resistant strains is important for the control of TB. Real-time polymerase chain reaction (RT-PCR) assays may detect all of the mutations that occur in the M. tuberculosis 81-bp core region of the rpoB gene, which is responsible for resistance to rifampin (RIF) and codon 315 of the katG gene and the inhA ribosomal binding site, which are responsible for isoniazid (INH). The goal of this study was to assess the performance of RT-PCR compared to traditional culture-based methods for determining the drug susceptibility of M. tuberculosis. BACTEC™ MGIT™ 960 was used as the gold standard method for phenotypic drug susceptibility testing. Susceptibilities to INH and RIF were also determined by genotyping of katG, inhA and rpoB genes. RT-PCR based on molecular beacons probes was used to detect specific point mutations associated with resistance. The sensitivities of RT-PCR in detecting INH resistance using katG and inhA targets individually were 55% and 25%, respectively and 73% when combined. The sensitivity of the RT-PCR assay in detecting RIF resistance was 99%. The median time to complete the RT-PCR assay was three-four hours. The specificities for tests were both 100%. Our results confirm that RT-PCR can detect INH and RIF resistance in less than four hours with high sensitivity. PMID:23147147

  4. The origin of UV-optical variability in AGN and test of disc models: XMM-Newton and ground-based observations of NGC 4395

    NASA Astrophysics Data System (ADS)

    McHardy, I. M.; Connolly, S. D.; Peterson, B. M.; Bieryla, A.; Chand, H.; Elvis, M. S.; Emmanoulopoulos, D.; Falco, E.; Gandhi, P.; Kaspi, S.; Latham, D.; Lira, P.; McCully, C.; Netzer, H.; Uemura, M.

    2016-05-01

    The origin of short timescale (weeks/months) variability of AGN, whether due to intrinsic disc variations or reprocessing of X-ray emission by a surrounding accretion disc, has been a puzzle for many years. However recently a number of observational programmes, particularly of NGC 5548 with Swift, have shown that the UV/optical variations lag behind the X-ray variations in a manner strongly supportive of X-ray reprocessing. Somewhat surprisingly, the implied size of the accretion disc is ∼3 times greater than expected from a standard, smooth, Shakura-Sunyaev thin disc model. Although the difference may be explained by a clumpy accretion disc, it is not clear whether the difference will occur in all AGN or whether it may change as, eg, a function of black hole mass, accretion rate, or disc temperature. Measurements of interband lags for most AGN require long timescale monitoring, which is hard to arrange. However for low mass (< 106 M⊙) AGN, the combination of XMM-Newton EPIC (X-rays) with the optical monitor in fast readout mode allows an X-ray/UV-optical lag to be measured within a single long observation. Here we summarise previous related observations and report on XMM-Newton observations of NGC 4395 (mass 100 times lower, accretion rate ∼20 times lower than for NGC 5548). We find that the UVW1 lags the X-rays by ∼ 470 s. Simultaneous observations at 6 different ground based observatories also allowed the g-band lag (∼ 800s) to be measured. These observations are in agreement with X-ray reprocessing but initial analysis suggests that, for NGC 4395, they do not differ markedly from the predictions of the standard thin disc model.

  5. Same-day identification and antibiotic susceptibility testing on positive blood cultures: a simple and inexpensive procedure.

    PubMed

    Maelegheer, K; Nulens, E

    2016-11-26

    Fast diagnostic tools are becoming a hot topic in microbiology, especially in the case of septic patients. Therefore, we attempted to develop a fast, inexpensive, accurate and easy method to identify bacteria and perform an antibiotic susceptibility test directly on positive blood cultures that could be used in a routine laboratory. A procedure based on centrifugation and washing steps was performed on 110 non-duplicated (including nine seeded) positive blood culture bottles. Direct identification (DID) and antimicrobial susceptibility testing (AST) was conducted on the pellet with the MALDI Biotyper and Phoenix, respectively. Identification (ID) to the species level was correct in 44/45 (97%) cases for Gram-negative bacteria and 44/56 (79%) cases for Gram-positive bacteria. In total, 98.9% of the AST results were identical to the routine laboratory result. No very major errors, four major errors and eight minor errors were detected. A reliable identification and a high AST agreement were obtained from blood cultures seeded with multi-resistant bacteria. We simulated the timeline of DID and demonstrated an identification and AST result within 24 h using Escherichia coli- and Staphylococcus aureus-positive blood cultures as examples. We developed an easy, fast and cheap method to generate reliable ID and AST results. Moreover, this method may be used to obtain results within 24 h after incubating the blood culture bottles in the microbiology lab.

  6. Irradiation Programs and Test Plans to Assess High-Fluence Irradiation Assisted Stress Corrosion Cracking Susceptibility.

    SciTech Connect

    Teysseyre, Sebastien

    2015-03-01

    . Irradiation assisted stress corrosion cracking (IASCC) is a known issue in current reactors. In a 60 year lifetime, reactor core internals may experience fluence levels up to 15 dpa for boiling water reactors (BWR) and 100+ dpa for pressurized water reactors (PWR). To support a safe operation of our fleet of reactors and maintain their economic viability it is important to be able to predict any evolution of material behaviors as reactors age and therefore fluence accumulated by reactor core component increases. For PWR reactors, the difficulty to predict high fluence behavior comes from the fact that there is not a consensus of the mechanism of IASCC and that little data is available. It is however possible to use the current state of knowledge on the evolution of irradiated microstructure and on the processes that influences IASCC to emit hypotheses. This report identifies several potential changes in microstructure and proposes to identify their potential impact of IASCC. The susceptibility of a component to high fluence IASCC is considered to not only depends on the intrinsic IASCC susceptibility of the component due to radiation effects on the material but to also be related to the evolution of the loading history of the material and interaction with the environment as total fluence increases. Single variation type experiments are proposed to be performed with materials that are representative of PWR condition and with materials irradiated in other conditions. To address the lack of IASCC propagation and initiation data generated with material irradiated in PWR condition, it is proposed to investigate the effect of spectrum and flux rate on the evolution of microstructure. A long term irradiation, aimed to generate a well-controlled irradiation history on a set on selected materials is also proposed for consideration. For BWR, the study of available data permitted to identify an area of concern for long term performance of component. The efficiency of

  7. Rapid method for detection, identification, and susceptibility testing of enteric pathogens.

    PubMed

    Stager, C E; Erikson, E; Davis, J R

    1983-01-01

    Three hundred and seven colonies believed to be enteric pathogens were selected from primary plates of MacConkey, xylose desoxycholate, or salmonella-shigella agar for inoculation to lactose-sucrose broth, urea-41 motility medium, modified Andrade glucose broth with inverted Durham tube, pregrowth broth, triple sugar iron agar, lysine iron agar (LIA), and Christensen urea agar. The rapid screen consisted of interpreting the lactose-sucrose, urea-41 motility, and modified Andrade glucose broth gas reactions after 4 to 6 h at 35 degrees C. These rapid screening biochemicals plus LIA were incubated for 24 h if further interpretation was required. Reference biochemicals (triple sugar iron, LIA, and Christensen urea agars) were interpreted at 24 h. Of 307 isolates, 49 (16%) were reported as negative for enteric pathogens after 4 to 6 h because their biochemical profiles were not compatible with those for enteric pathogens. A total of 87 (28.3%) isolates produced biochemical profiles at 4 to 6 h that were presumptive for enteric pathogens. The 87 presumptive pathogens were inoculated into the AutoMicrobic system Gram-Negative General Susceptibility Card and the AutoMicrobic system Enterobacteriaceae-Plus Biochemical Card (AMS-EBC+) after 4 to 6 h of growth in pregrowth broth. Of these isolates, 63 were confirmed to be enteric pathogens, of which 61 (96.8%) were correctly identified by the AMS-EBC+. One isolate was identified as Shigella dysenteriae by AMS-EBC+ but confirmed as Shigella flexneri biotype 6 by a reference laboratory. The other isolate was identified as Arizona hinshawii by AMS-EBC+ but was confirmed as Salmonella enteritidis. Of the 307 isolates, 166 (54.1%) required further interpretation of the rapid screening biochemicals plus LIA at 24 h; 5 of these were detected as enteric pathogens. The same 68 enteric pathogens were detected by both the rapid method and the reference method. The results from the general susceptibility card agreed with agar diffusion

  8. Multi-gene panel testing for hereditary cancer susceptibility in a rural Familial Cancer Program.

    PubMed

    Hermel, David J; McKinnon, Wendy C; Wood, Marie E; Greenblatt, Marc S

    2017-01-01

    This study explores our Familial Cancer Program's experience implementing multi-gene panel testing in a largely rural patient population. We conducted a retrospective review of patients undergoing panel testing between May 2011 and August 2015. Our goal was to evaluate factors that might be predictors of identifying variants (pathogenic or uncertain significance) and to assess clinical management changes due to testing. We utilized a structured family history tool to determine the significance of patient's family histories with respect to identification of genetic variants. A total of 227 patients underwent panel testing at our center and 67 patients (29.5 %) had variants identified, with 8 (3.5 %) having multiple variants. Overall, 44 patients (19.4 %) had a variant of uncertain significance (VUS) and 28 patients (12.3 %) had a pathogenic variant detected, with 10 (4.4 %) having pathogenic variants in highly penetrant genes. We found no statistical difference in patient familial and personal cancer history, age, rural status, Ashkenazi Jewish ancestry, insurance coverage and prior single-gene testing among those with pathogenic, VUS and negative panel testing results. There were no predictors of pathogenic variants on regression analysis. Panel testing changed cancer screening and management guidelines from that expected based on family history alone in 13.2 % of patients. Ultimately, cancer panel testing does yield critical information not identified by traditional single gene testing but maximal utility through a broad range of personal and family histories requires improved interpretation of variants.

  9. Predicting susceptibility of alloy 600 to intergranular stress corrosion cracking using a modified electrochemical potentiokinetic reactivation test

    SciTech Connect

    Ahn, M.K.; Kwon, H.S.; Lee, J.H.

    1995-06-01

    Modified double-loop electrochemical potentiokinetic reactivation (DL-EPR) tests were applied to evaluate the degree of sensitization (DOS) for alloy 600 aged at 700 C. Results of the modified DL-EPR test were compared to intergranular stress corrosion cracking (IGSCC) susceptibilities determined in deaerated 0.01 M sodium tetrathionate under deformation at a constant strain rate of 0.93 {times} 10{sup {minus}6}/s. By analyzing the effects of solution concentration, temperature, and scan rate on the electrochemical response in the EPR tests and the morphologies, the optimal modified DL-EPR test condition for alloy 600 was obtained in 0.01 M sulfuric acid + 10 ppm potassium thiocyanate at 25 C and at a scan rate of 0.5 mV/s. The standard DL-EPR test, performed under conditions of 0.5 M H{sub 2}SO{sub 4} + 0.01 M KCNS at 30 C and a scan rate of 1.67 mV/s, provided very poor discriminating power for various DOS of alloy 600 because general and pitting corrosion occurred, in addition to intergranular corrosion. The modified test, however, was highly discriminating because of its highly selective corrosion attack at grain boundaries. IGSCC occurred in samples of alloy 600 aged for < 20 h, and susceptibility to IGSCC{sub s} increased with decreasing aging times up to 1 h, showing maximum IGSCC{sub s} in the sample aged for 1 h. IGSCC{sub s} for the alloy was found to be associated closely with the chromium-depleted profile across grain boundaries. The deeper and narrower chromium-depleted zone produced greater IGSCC{sub s}. It was demonstrated that DOS measured by the modified DL-EPR test was correlated more closely with IGSCC{sub s} than was DOS measured by the standard EPR test. This correlation resulted from the fact that the modified EPR test selectively attacked the more deeply chromium-depleted regions in comparison to the standard EPR test.

  10. In vitro susceptibility testing of Mycobacterium tuberculosis complex strains isolated from seals to antituberculosis drugs.

    PubMed

    Bernardelli, Amelia; Morcillo, Nora; Loureiro, Julio; Quse, Viviana; Davenport, Silvana

    2004-06-01

    Mycobacteria strains belonging to the Mycobacterium tuberculosis complex were isolated from seals found in the South Atlantic. The animals were received in Mundo Marino installations and treated for Mycobacterium tuberculosis complex by conventional therapy of intensive care and enriched food supply; however, in all cases treatment failed. Necropsies of all animals revealed extensive lesions compatible with tuberculosis involving lungs, liver, spleen and lymphatic nodes. Classical biochemical methods as well as molecular techniques using the IS6110 probes were performed for mycobacterial identification. Furthermore, the LCx M. tuberculosis assay (Abbott Laboratories) identified all strains as Mycobacterium tuberculosis complex members. The in vitro susceptibility pattern was examined in mycobacterial strains isolated from seven seals and in 3 reference strains--BCG, H37Rv (M. tuberculosis) and AN5 (Mycobacterium bovis)--to 4 medications--isoniazid, rifampin, streptomycin and ethambutol. Minimal inhibitory drug concentrations were determined by the Mycobacterial Growth Indicator Tube (BD Argentina) method and a microdilution and colorimetric assay using 3-(4-5 dimethyltiazol-2)-2,5 diphenyltetrazolium bromide. All the isolates and the reference strains BCG and AN5 were inhibited by MIC values similar to those of H37Rv with good agreement obtained by both techniques. These findings suggest that a therapeutic regimen aimed to seals diagnosed with tuberculosis play an important role in the prevention of tuberculosis transmission from infected animals to humans that are in routine contact with them.

  11. Rapid susceptibility testing of mycobacterium avium complex and mycobacterium tuberculosis isolated from AIDS patients

    NASA Technical Reports Server (NTRS)

    Dhople, Arvind M.

    1993-01-01

    In ominous projections issued by both U.S. Public Health Service and the World Health Organization, the epidemic of the Human Immunodeficiency Virus (HIV) infection will continue to rise more rapidly worldwide than predicted earlier. The Acquired Immunodeficiency Syndrome (AIDS) patients are susceptible to diseases called opportunistic infections of which tuberculosis and M. avium Complex (MAC) infection are most common. This has created an urgent need to uncover new drugs for the treatment of these infections. In the seventies, NASA scientists at Goddard Space Flight Center, Greenbelt, Maryland, had adopted a biochemical indicator, adenosine triphosphate (ATP), to detect presence of life in extraterrestrial space. Therefore, we proposed to develop ATP assay technique to determine sensitivity of antibacterial compounds against MAC and M. tuberculosis. The work was initiated in June 1992. In the last report, we described our efforts in developing ATP assay method using MAC. Studies were continued further, and during the period of this report, we established the relationship between colony forming units and ATP levels of these organisms during the growth cycle. Also, we evaluated the effects of standard antimycobacterial drugs using ATP assay technique and compared the results with those obtained with conventional tube dilution proportional method.

  12. Design concepts in lumbar total disc arthroplasty

    PubMed Central

    Bellini, Chiara M.; Zweig, Thomas; Ferguson, Stephen; Raimondi, Manuela T.; Lamartina, Claudio; Brayda-Bruno, Marco; Fornari, Maurizio

    2008-01-01

    The implantation of lumbar disc prostheses based on different design concepts is widely accepted. This paper reviews currently available literature studies on the biomechanics of TDA in the lumbar spine, and is targeted at the evaluation of possible relationships between the aims of TDA and the geometrical, mechanical and material properties of the various available disc prostheses. Both theoretical and experimental studies were analyzed, by a PUBMED search (performed in February 2007, revised in January 2008), focusing on single level TDA. Both semi-constrained and unconstrained lumbar discs seem to be able to restore nearly physiological IAR locations and ROM values. However, both increased and decreased ROM was stated in some papers, unrelated to the clinical outcome. Segmental lordosis alterations after TDA were reported in most cases, for both constrained and unconstrained disc prostheses. An increase in the load through the facet joints was documented, for both semi-constrained and unconstrained artificial discs, but with some contrasting results. Semi-constrained devices may be able to share a greater part of the load, thus protecting the surrounding biological structure from overloading and possible early degeneration, but may be more susceptible to wear. The next level of development will be the biomechanical integration of compression across the motion segment. All these findings need to be supported by long-term clinical outcome studies. PMID:18946684

  13. Investigation of cryogenic rupture disc design

    NASA Technical Reports Server (NTRS)

    Keough, J. B.; Oldland, A. H.

    1973-01-01

    Rupture disc designs of both the active (command actuated) and passive (pressure ruptured) types were evaluated for performance characteristics at cryogenic temperatures and for capability to operate in a variety of cryogens, including gaseous and liquid fluorine. The test results, coupled with information from literature and industry searches, were used to establish a statement of design criteria and recommended practices for application of rupture discs to cryogenic rocket propellant feed and vent systems.

  14. The role of disease perceptions and results sharing in psychological adaptation after genetic susceptibility testing: the REVEAL Study.

    PubMed

    Ashida, Sato; Koehly, Laura M; Roberts, J Scott; Chen, Clara A; Hiraki, Susan; Green, Robert C

    2010-12-01

    This study evaluates the extent to which psychological adaptation (validated measures of depressive symptoms, anxiety, and test-specific distress) after genetic susceptibility testing is influenced by changes in beliefs about Alzheimer's disease (AD) and sharing of test results with others. Adult children of AD patients (N=269) from a randomized clinical trial involving genetic testing for apolipoprotein E (APOE) provided information before, as well as 6 weeks and 12 months after results disclosure. The levels of adaptation varied highly among participants at 12-month assessment. Participants who learned that they were ε4 negative (lower risk) had a reduction in perceived risk and concern about developing AD compared with those who learned that they were ε4 positive. Those who received results through an extended educational protocol (three in-person visits) had a larger decline in AD concern than those in a condensed protocol (educational brochure and two in-person visits). Increase in AD concern 6 weeks after disclosure was associated with increase in depression scores (b=0.20, P<0.01) and anxiety levels (b=0.20, P<0.01), and higher distress associated with AD genetic testing (b=0.18, P=0.02) 1 year after testing. Increase in perceived risk (b=0.16, P=0.04) was also associated with higher AD genetic testing distress. Sharing the test results with health professionals and friends (but not family) was associated with decrease in depression (b=-0.11, P=0.05) and anxiety levels (b=-0.16, P<0.01), respectively after a year. Enhancing discussion with regard to risks and concerns about AD during pretesting counseling and obtaining support through sharing the results after testing may help facilitate test recipients' long-term psychological adaptation.

  15. Social defeat interacts with Disc1 mutations in the mouse to affect behavior.

    PubMed

    Haque, F Nipa; Lipina, Tatiana V; Roder, John C; Wong, Albert H C

    2012-08-01

    DISC1 (Disrupted-in-schizophrenia 1) is a strong candidate susceptibility gene for psychiatric disease that was originally discovered in a family with a chromosomal translocation severing this gene. Although the family members with the translocation had an identical genetic mutation, their clinical diagnosis and presentation varied significantly. Gene-environment interactions have been proposed as a mechanism underlying the complex heritability and variable phenotype of psychiatric disorders such as major depressive disorder and schizophrenia. We hypothesized that gene-environment interactions would affect behavior in a mutant Disc1 mouse model. We examined the effect of chronic social defeat (CSD) as an environmental stressor in two lines of mice carrying different Disc1 point mutations, on behaviors relevant to psychiatric illness: locomotion in a novel open field (OF), pre-pulse inhibition (PPI) of the acoustic startle response, latent inhibition (LI), elevated plus maze (EPM), forced swim test (FST), sucrose consumption (SC), and the social interaction task for sociability and social novelty (SSN). We found that Disc1-L100P +/- and wild-type mice have similar anxiety responses to CSD, while Q31L +/- mice had a very different response. We also found evidence of significant gene-environment interactions in the OF, EPM and SSN.

  16. Methods of measuring zones of inhibition with the Bauer-Kirby disk susceptibility test.

    PubMed

    Barry, A L; Coyle, M B; Thornsberry, C; Gerlach, E H; Hawkinson, R W

    1979-12-01

    Standard Bauer-Kirby disk tests were performed with 85 selected isolates, each tested in triplicate by four different investigators. Each disk test was observed, and zone diameters were measured, under two lighting conditions (transmitted light and reflected light). The two lighting systems produced similar zone measurements (+/-2 mm) with 96% of the tests. When there were greater differences, zones appeared to be larger when observed with reflected light. Interlaboratory reproducibility was much greater when using reflected light rather than transmitted light. We concluded that zone diameters should be measured from the back of the plate while it is resting on, or held 2 to 3 inches [ca. 5.1 to 7.6 cm] above, a black, nonreflecting, flat surface, illuminated by a reflected light source.

  17. Development of laser beam welding transverse-varestraint test for assessment of solidification cracking susceptibility in laser welds

    NASA Astrophysics Data System (ADS)

    Chun, Eun-Joon; Baba, Hayato; Nishimoto, Kazutoshi; Saida, Kazuyoshi

    2015-05-01

    In order to quantitatively evaluate the solidification cracking susceptibility in laser welds of type 310S stainless steel, a transverse-Varestraint testing system using a laser beam welding apparatus was newly constructed. The timing-synchronization between the laser oscillator, welding robot and hydraulic pressure devices was established by employing high-speed camera observations together with electrical signal control among the three components. Moreover, the yoke-drop time measured by the camera was used to prevent underestimation of the crack length. The laser beam melt-run welding used a variable welding speed from 10.0 to 40.0 mm/s, while the gas tungsten arc welding varied the welding speed from 1.67 to 5.00 mm/s. As the welding speed increased from 1.67 to 40.0mm/s, the solidification brittle temperature range of type 310S stainless steel welds was reduced from 146 to 120 K. It follows that employing the laser beam welding process mitigates the solidification cracking susceptibility for type 310S stainless steel welds.

  18. Legal and ethical issues in genetic testing and counseling for susceptibility to breast, ovarian and colon cancer.

    PubMed Central

    Dickens, B M; Pei, N; Taylor, K M

    1996-01-01

    The prediction of susceptibility to heritable breast, ovarian and colon cancer raises important legal and ethical concerns. Health care professionals have a duty to disclose sufficient information to enable patients to make informed decisions. They must also safeguard the confidentiality of patient data. These duties may come into conflict if a positive finding in one patient implies that family members are also at risk. A legal distinction is made between a breach of confidentiality and the legitimate sharing of information in a patient's interest or to prevent harm to a third party. Physicians also have a fiduciary duty to warn. Other issues concern the legal liability assumed by genetic counsellors, whose disclosures may influence decisions about childbearing, for example, and the risk of socioeconomic discrimination faced by people with a known genetic susceptibility. Traditional ethical orientations and principals may be applied to these and other questions, but feminist ethics will likely have particular importance in the development of an ethical stance toward testing and counseling for heritable breast and ovarian cancer. PMID:8634959

  19. Candida glabrata species complex prevalence and antifungal susceptibility testing in a culture collection: First description of Candida nivariensis in Argentina.

    PubMed

    Morales-López, Soraya Eugenia; Taverna, Constanza G; Bosco-Borgeat, María Eugenia; Maldonado, Ivana; Vivot, Walter; Szusz, Wanda; Garcia-Effron, Guillermo; Córdoba, Susana B

    2016-12-01

    The presence of the cryptic species belonging to the Candida glabrata complex has not been studied in Argentina. We analyzed a collection of 117 clinical isolates of C. glabrata complex belonging to a National Culture Collection of Instituto Nacional de Microbiología "Dr. Carlos G. Malbrán" from Argentina (40 isolates from blood samples, 18 from other normally sterile sites, 20 from vagina, 14 from urine, 7 from oral cavity, 3 from catheter, 1 from a stool sample and 14 isolates whose clinical origin was not recorded). The aims of this work were to determine the prevalence of the cryptic species Candida nivariensis and Candida bracarensis and to evaluate the susceptibility profile of isolates against nine antifungal drugs. Identification was carried out by using classical phenotypic tests, CHROMagar™ Candida, PCR and MALDI-TOF. The minimal inhibitory concentrations of amphotericin B, 5-fluorocytosine, fluconazole, itraconazole, voriconazole, ketoconazole, posaconazole, caspofungin and anidulafungin were determined according to the EDef 7.3 (EUCAST) reference document. Of the 117 isolates, 114 were identified as C. glabrata and three as C. nivariensis by using PCR and MALDI-TOF. There were no major differences between C. nivariensis and C. glabrata susceptibility profiles. No resistant strains were found to echinocandins. We have found that the percentage of C. nivariensis in our culture collection was 2.56. This is the first description of C. nivariensis in Argentina, and data obtained could contribute to the knowledge of the epidemiology of this cryptic species.

  20. Fluconazole susceptibility and ERG11 gene expression in vaginal candida species isolated from lagos Nigeria

    PubMed Central

    Pam, Victoria K; Akpan, Juliet U; Oduyebo, Oyinlola O; Nwaokorie, Francisca O; Fowora, Muinah A; Oladele, Rita O; Ogunsola, Folasade T; Smith, Stella I

    2012-01-01

    Fluconazole resistance is an important type of resistance in Candida because in most countries, fluconazole is the drug of choice for vulvovaginal candidiasis. Candida species resist fluconazole by various mechanisms but there is paucity of data on these in our environment. Such mechanisms include among others, over-expression of the ERG11 gene, which codes for synthesis of the target enzymes in the fungus. The aim of this study was to screen Candida spp. resistant to fluconazole for the expression of ERG11 gene. Fluconazole susceptibility test was performed on 28 clinical strains of Candida species previously obtained from students of a School of Nursing in Lagos, Nigeria. They were identified by API Candida, CHROMagar candida and germ tube test. Using 25 mcg discs, fluconazole susceptibility was determined by the disc diffusion method and results were interpreted in accordance with the Clinical Laboratory Standard Institute (CLSI) criteria; sensitive (S), resistant (R) and susceptible dose dependent (SDD). The R and SDD isolates were subsequently evaluated for the presence of ERG11 gene. Of the 28 clinical isolates, 14 were identified as C. albicans and six as C. tropicalis. The remaining isolates were identified as C. glabrata (2), C. famata (2) C. kefyr (2) one each of C. parapsilosis and C. guilliermondii respectively. In this study, 18 were susceptible (S) to fluconazole, eight were SDD and two were resistant to the antifungal agent. Out of the 14 C. albicans isolates, 12 were susceptible, one showed high level resistance and similar number showed susceptible dose dependence. ERG11 was detected in three susceptible dose dependent Candida species. This analysis demonstrates that susceptible dose dependence should not be overlooked as it may be associated with the presence of ERG11 gene and resistance to fluconazole. There is a need to consider routine antifungal susceptibility testing for Candida species causing vulvovaginitis. PMID:22493755

  1. Factors associated with an individual's decision to withdraw from genetic testing for breast and ovarian cancer susceptibility: implications for counseling.

    PubMed

    Godard, Béatrice; Pratte, Annabelle; Dumont, Martine; Simard-Lebrun, Adèle; Simard, Jacques

    2007-01-01

    Our study aimed to examine why individuals withdraw from genetic testing for breast and ovarian cancer susceptibility. We explored the characteristics of 334 individuals from high-risk breast and ovarian cancer families who declined genetic testing for BRCA1/2 mutations, when, and why they did so. Individuals who declined genetic testing were older, and a greater proportion had never developed breast or ovarian cancer. Fifty one per cent (51.1%) of individuals withdrew after the first genetic counseling session. Most of those who declined were afraid of the psychological effects of genetic testing (36.3%). The next most-cited explanations concerned logistic problems such as a limited ability to travel, lack of time, personal issues, advanced age, or health problems (21.7%). The third category included individuals who did not see any advantage in being tested (14.5%). Insurability was a concern (5.9%), mainly for men. Surprisingly, confidentiality was not a frequently reported issue (1.3%). Sixty eight per cent (68%) of individuals belonging to a family in which at least one individual has been tested withdrew after the presence of a deleterious BRCA1/2 mutation in a relative was disclosed, compared to 42% after the disclosure of a nonconclusive test result in at least one relative. Concern about the psychological effects of the result was still one of the major reasons. Several factors may influence an individual's decision to decline genetic testing; a greater understanding of these issues may help health professionals to better meet the needs and concerns of individuals from high-risk families, thus possibly improving their health outcomes.

  2. Inter- and Intra-Assay Reproducibility of Microplate Alamar Blue Assay Results for Isoniazid, Rifampicin, Ethambutol, Streptomycin, Ciprofloxacin, and Capreomycin Drug Susceptibility Testing of Mycobacterium tuberculosis▿ †

    PubMed Central

    Leonard, Brian; Coronel, Jorge; Siedner, Mark; Grandjean, Louis; Caviedes, Luz; Navarro, Pilar; Gilman, Robert H.; Moore, David A. J.

    2008-01-01

    The intersample and intrasample variability of the results obtained with the microplate Alamar blue assay for the indirect drug susceptibility testing of Mycobacterium tuberculosis was investigated. Between 1.2 and 8.5% of paired MICs differed by more than one twofold dilution, resulting in discordant susceptible-resistant designations at frequencies between 0.6% (rifampin) and 18.9% (ethambutol). PMID:18701659

  3. Evaluation of disk diffusion and Etest compared to broth microdilution for antifungal susceptibility testing of posaconazole against clinical isolates of filamentous fungi.

    PubMed

    Messer, Shawn A; Diekema, Daniel J; Hollis, Richard J; Boyken, Linda B; Tendolkar, Shailesh; Kroeger, Jennifer; Pfaller, Michael A

    2007-04-01

    We performed Etest, disk diffusion, and broth microdilution susceptibility testing of posaconazole against 146 clinical isolates of filamentous fungi. By using provisional breakpoints for comparison purposes only, categorical agreement between the results of the agar-based methods and those of broth microdilution were 96 to 98%, with no very major errors. These agar-based methods hold promise as simple and reliable methods for determining the posaconazole susceptibilities of filamentous fungi.

  4. Susceptibility to Faking of the Defining Issues Test of Moral Development

    ERIC Educational Resources Information Center

    McGeorge, Colin

    1975-01-01

    Reports the results of an experiment in which 146 college freshmen were asked either to fake bad answers, fake good answers or record their own views on the Defining Issues Test. Findings indicated that students could not fake higher scores, but could fake bad scores. (SDH)

  5. Antimicrobial susceptibility of 51 strains of Haemophilus pleuropneumoniae.

    PubMed Central

    Gilbride, K A; Rosendal, S

    1984-01-01

    Fifty-one strains of Haemophilus pleuropneumoniae were tested for susceptibility to 27 antimicrobial agents using agar disc diffusion, broth-tube dilution and microdilution methods. There was generally good agreement between the interpretation of the disc diffusion inhibition zones and the actual minimal inhibitory concentrations obtained with the dilution methods. The agreement between the results obtained with the broth-tube dilution method and the microdilution method was very good. Three strains were resistant to penicillin, ampicillin, carbenicillin, methicillin and tetracycline. One of those was also resistant to chloramphenicol. Forty strains were resistant to streptomycin, 23 strains were resistant to novobiocin and seven were resistant to triple sulfa. It is thus necessary to consider resistance development against antimicrobial agents chosen for the treatment of pleuro-pneumonia in pigs caused by Haemophilus pleuropneumoniae. PMID:6713256

  6. Identification and Antifungal Susceptibility Testing of Candida Species: A Comparison of Vitek-2 System with Conventional and Molecular Methods

    PubMed Central

    Kaur, Ravinder; Dhakad, Megh Singh; Goyal, Ritu; Haque, Absarul; Mukhopadhyay, Gauranga

    2016-01-01

    Background: Candida infection is a major cause of morbidity and mortality in immunocompromised patients; an accurate and early identification is a prerequisite need to be taken as an effective measure for the management of patients. The purpose of this study was to compare the conventional identification of Candida species with identification by Vitek-2 system and the antifungal susceptibility testing (AST) by broth microdilution method with Vitek-2 AST system. Materials and Methods: A total of 172 Candida isolates were subjected for identification by the conventional methods, Vitek-2 system, restriction fragment length polymorphism, and random amplified polymorphic DNA analysis. AST was carried out as per the Clinical and Laboratory Standards Institute M27-A3 document and by Vitek-2 system. Results: Candida albicans (82.51%) was the most common Candida species followed by Candida tropicalis (6.29%), Candida krusei (4.89%), Candida parapsilosis (3.49%), and Candida glabrata (2.79%). With Vitek-2 system, of the 172 isolates, 155 Candida isolates were correctly identified, 13 were misidentified, and four were with low discrimination. Whereas with conventional methods, 171 Candida isolates were correctly identified and only a single isolate of C. albicans was misidentified as C. tropicalis. The average measurement of agreement between the Vitek-2 system and conventional methods was >94%. Most of the isolates were susceptible to fluconazole (88.95%) and amphotericin B (97.67%). The measurement of agreement between the methods of AST was >94% for fluconazole and >99% for amphotericin B, which was statistically significant (P < 0.01). Conclusion: The study confirmed the importance and reliability of conventional and molecular methods, and the acceptable agreements suggest Vitek-2 system an alternative method for speciation and sensitivity testing of Candida species infections. PMID:27942193

  7. Synthesis and Testing of Polymers Susceptible to Hydrolysis by Proteolytic Enzymes

    DTIC Science & Technology

    1974-08-01

    Polycaprolactone 4. Polyteirs containing • hydroxy acids II. METHODS UEVELOPMIENT A. Exposure of Materials to Enzymes After the synthesis and purification of d...to our benzylated nylon samples. A 6 day test with therinolysin, chyniotrypsin, and subtilisin showed that the mere presence of the polymer caused...and subtilisin . C. Analytical Procedures for Measurinq Degradation 1. Weight Loss By weighing the solid polymer before and after exposure to enzyme

  8. Characterization of variables that may influence ozenoxacin in susceptibility testing, including MIC and MBC values.

    PubMed

    Tato, Marta; López, Yuly; Morosini, Maria Isabel; Moreno-Bofarull, Ana; Garcia-Alonso, Fernando; Gargallo-Viola, Domingo; Vila, Jordi; Cantón, Rafael

    2014-03-01

    Ozenoxacin is a new des-fluoro-(6)-quinolone active against pathogens involved in skin and skin structure infections, including Gram-positives resistant to fluoroquinolones. The in vitro bacteriostatic and bactericidal activity of ozenoxacin, ciprofloxacin, and levofloxacin was studied against 40 clinical isolates and 16 ATCC quality control strains under different test conditions, including cation supplementation, pH, inoculum size, inoculum preparation, incubation time, human serum, and CO2 incubation. The activity of ozenoxacin was unaffected by cation test medium supplementation, inoculum preparation, incubation time, and the increasing CO2 environment. On the contrary, ozenoxacin activity decreased by high inoculum (10(7) CFU/mL), increased presence of human serum in the medium, and increased pH. The last effect was different for ciprofloxacin and levofloxacin, which decreased activity when pH decreased. The bactericidal mode of action of ozenoxacin and control drugs was consistently maintained (MBC/MIC ratios ≤4) in spite of variations of their activity under different test conditions.

  9. Holographic optical disc

    NASA Astrophysics Data System (ADS)

    Zhou, Gan; An, Xin; Pu, Allen; Psaltis, Demetri; Mok, Fai H.

    1999-11-01

    The holographic disc is a high capacity, disk-based data storage device that can provide the performance for next generation mass data storage needs. With a projected capacity approaching 1 terabit on a single 12 cm platter, the holographic disc has the potential to become a highly efficient storage hardware for data warehousing applications. The high readout rate of holographic disc makes it especially suitable for generating multiple, high bandwidth data streams such as required for network server computers. Multimedia applications such as interactive video and HDTV can also potentially benefit from the high capacity and fast data access of holographic memory.

  10. Vertical cup/disc ratio in relation to optic disc size: its value in the assessment of the glaucoma suspect

    PubMed Central

    Garway-Heath, D.; Ruben, S.; Viswanathan, A.; Hitchings, R.

    1998-01-01

    AIMS—The vertical cup/disc ratio (CDR) has long been used in the assessment of the glaucoma suspect, though the wide range of CDR values in the normal population limits its use. Cup size is related physiologically to disc size and pathologically to glaucomatous damage. Disc size can be measured at the slit lamp as the vertical disc diameter (DD). The ability of the CDR, in relation to DD, to identify glaucomatous optic discs was investigated.
METHODS—88 normal, 53 early glaucoma, and 59 ocular hypertensive subjects underwent stereoscopic optic disc photography and clinical biometry. Photographs were analysed in a masked fashion by computer assisted planimetry. The relation between vertical cup diameter and DD was explored by linear regression, and expressed in terms of CDR. The upper limit of normal was defined by the 95% prediction intervals of this regression (method 1) and by the upper 97.5 percentile for CDR (method 2). The sensitivity and specificity of CDR to identify an optic disc as glaucomatous was tested with these disc size dependent and disc size independent cut offs in small, medium, and large discs.
RESULTS—The CDR was related to DD by the equation CDR = (−1.31 + (1.194 × DD))/DD. The sensitivity in small, medium, and large discs was 80%, 60%, and 38% respectively for method 1 and 33%, 67%, and 63% respectively for method 2. Specificity was 98.9% (method 1) and 97.7% (method 2).
CONCLUSIONS—The CDR, relative to disc size, is useful clinically, especially to assist in identifying small glaucomatous discs.

 Keywords: cup/disc ratio; glaucoma; imaging PMID:9924296

  11. Does increased heat resistance result in higher susceptibility to predation? A test using Drosophila melanogaster selection and hardening.

    PubMed

    Hangartner, Sandra; Dworkin, Ian; DeNieu, Michael; Hoffmann, Ary A

    2017-04-07

    Heat resistance of ectotherms can be increased both by plasticity and evolution, but these effects may have trade-offs resulting from biotic interactions. Here we test for predation costs in Drosophila melanogaster populations with altered heat resistance produced by adult hardening and directional selection for increased heat resistance. In addition, we also tested for genetic trade-offs by testing heat resistance in lines that have evolved under increased predation risk. We show that while 35/37°C hardening increases heat resistance as expected, it does not increase predation risk from jumping spiders or mantids; in fact there was an indication that survival may have increased under predation following a triple 37°C compared to a single 35°C hardening treatment. Flies that survived a 39°C selection cycle showed lower survival under predation, suggesting a predation cost of exposure to a more severe heat stress. There was however no correlated response to selection because survival did not differ between control and selected lines after selection was relaxed for one or two generations. In addition, lines selected for increased predation risk did not differ in heat resistance. Our findings suggest independent evolutionary responses to predation and heat as measured in laboratory assays, and no costs of heat hardening on susceptibility to predation. This article is protected by copyright. All rights reserved.

  12. In vitro antimicrobial activity of benzoyl peroxide against Propionibacterium acnes assessed by a novel susceptibility testing method.

    PubMed

    Okamoto, Kazuaki; Ikeda, Fumiaki; Kanayama, Shoji; Nakajima, Akiko; Matsumoto, Tatsumi; Ishii, Ritsuko; Umehara, Masatoshi; Gotoh, Naomasa; Hayashi, Naoki; Iyoda, Takako; Matsuzaki, Kaoru; Matsumoto, Satoru; Kawashima, Makoto

    2016-06-01

    Benzoyl peroxide (BPO), a therapeutic agent for acne vulgaris, was assessed for in vitro antimicrobial activity against Propionibacterium acnes using a novel broth microdilution testing that improved BPO solubility. We searched for a suitable culture medium to measure the minimum inhibitory concentration (MIC) of BPO against P. acnes and finally found the Gifu anaerobic medium (GAM) broth supplemented with 0.1(v/v)% glycerol and 2(v/v)% Tween 80, in which BPO dissolved up to 1250 μg/mL and P. acnes grew well. The MICs and minimum bactericidal concentrations (MBCs) of BPO against 44 clinical isolates of P. acnes collected from Japanese patients with acne vulgaris were determined by our testing method using the supplemented GAM broth. The MICs of BPO were 128 or 256 μg/mL against all isolates of P. acnes regardless of susceptibility to nadifloxacin or clindamycin. The MBCs of BPO were also 128 or 256 μg/mL against the same isolates. Moreover, BPO at the MIC showed a rapid bactericidal activity against P. acnes ATCC11827 in time-kill assay. In conclusion, we could develop a novel assay for the MIC and MBC determinations of BPO against P. acnes, which is reliable and reproducible as a broth microdilution testing and the present results suggest that BPO has a potent bactericidal activity against P. acnes.

  13. Evaluation of the Wider System, a New Computer-Assisted Image-Processing Device for Bacterial Identification and Susceptibility Testing

    PubMed Central

    Cantón, Rafael; Pérez-Vázquez, María; Oliver, Antonio; Sánchez Del Saz, Begoña; Gutiérrez, M. Olga; Martínez-Ferrer, Manuel; Baquero, Fernando

    2000-01-01

    The Wider system is a newly developed computer-assisted image-processing device for both bacterial identification and antimicrobial susceptibility testing. It has been adapted to be able to read and interpret commercial MicroScan panels. Two hundred forty-four fresh consecutive clinical isolates (138 isolates of the family Enterobacteriaceae, 25 nonfermentative gram-negative rods [NFGNRs], and 81 gram-positive cocci) were tested. In addition, 100 enterobacterial strains with known β-lactam resistance mechanisms (22 strains with chromosomal AmpC β-lactamase, 8 strains with chromosomal class A β-lactamase, 21 broad-spectrum and IRT β-lactamase-producing strains, 41 extended-spectrum β-lactamase-producing strains, and 8 permeability mutants) were tested. API galleries and National Committee for Clinical Laboratory Standards (NCCLS) microdilution methods were used as reference methods. The Wider system correctly identified 97.5% of the clinical isolates at the species level. Overall essential agreement (±1 log2 dilution for 3,719 organism-antimicrobial drug combinations) was 95.6% (isolates of the family Enterobacteriaceae, 96.6%; NFGNRs, 88.0%; gram-positive cocci, 95.6%). The lowest essential agreement was observed with Enterobacteriaceae versus imipenem (84.0%), NFGNR versus piperacillin (88.0%) and cefepime (88.0%), and gram-positive isolates versus penicillin (80.4%). The category error rate (NCCLS criteria) was 4.2% (2.0% very major errors, 0.6% major errors, and 1.5% minor errors). Essential agreement and interpretive error rates for eight β-lactam antibiotics against isolates of the family Enterobacteriaceae with known β-lactam resistance mechanisms were 94.8 and 5.4%, respectively. Interestingly, the very major error rate was only 0.8%. Minor errors (3.6%) were mainly observed with amoxicillin-clavulanate and cefepime against extended-spectrum β-lactamase-producing isolates. The Wider system is a new reliable tool which applies the image

  14. Evaluation of a Novel Kit for Use with the BacT/ALERT 3D System for Drug Susceptibility Testing of Mycobacterium tuberculosis

    PubMed Central

    Werngren, Jim; Klintz, Lisbeth; Hoffner, Sven E.

    2006-01-01

    We evaluated a new protocol for the BacT/ALERT MB susceptibility test (bioMérieux Inc., Durham, NC) using 80 Mycobacterium tuberculosis WHO challenge panel strains. The drug susceptibility profiles of these strains are well characterized, and consensus drug resistance results have been established after tests were performed at around 20 international reference laboratories using recommended reference drug susceptibility techniques. Strains were tested according to the bioMérieux protocol using the following critical concentrations: rifampin (RIF), 0.9 mg/liter; isoniazid (INH), 0.4 and 0.09 mg/liter; and ethambutol (EMB), 1.8 mg/liter. The BacT/ALERT system detected 36/37 RIF-resistant strains. For INH (low concentration), 59/59 resistant strains were detected, and for EMB, 34/34 resistant strains were detected. Thus, the sensitivities were 97%, 100%, and 100% for RIF, INH, and EMB, respectively. The corresponding specificities were 100%, 95%, and 98%, respectively, for the same drugs. As soon as the BacT/ALERT MP seed bottle flagged positive, the median time to obtain a susceptibility results was 7.8 days. The results show good concordance with the consensus results of the international reference laboratories and demonstrate that BacT/ALERT 3D should be considered as an alternative method for rapid and automated drug susceptibility testing of M. tuberculosis. PMID:16757609

  15. Bryan total disc arthroplasty: a replacement disc for cervical disc disease

    PubMed Central

    Wenger, Markus; Markwalder, Thomas-Marc

    2010-01-01

    Total disc arthroplasty is a new option in the treatment of cervical degenerative disc disease. Several types of cervical disc prostheses currently challenge the gold-standard discectomy and fusion procedures. This review describes the Bryan Cervical Disc System and presents the Bryan prosthesis, its indications, surgical technique, complications, and outcomes, as given in the literature. PMID:22915917

  16. An Experimental Test of How Different Community Configurations and Environmental Pressures Influence the Susceptibility of Ponds to a Critical Transition

    NASA Astrophysics Data System (ADS)

    Gregory-Eaves, I.; Iacarella, J.; Giani, A.; Beisner, B. E.

    2015-12-01

    Over the past two centuries, humans have been modifying the planet at an accelerating rate and, in some cases, ecosystems have been observed to experience critical transitions. For example, shallow lakes and ponds may change abruptly from a clear-water, macrophyte-dominated state to a turbid state when exposed to minor increases in stress (e.g., nutrient loading). Yet, abrupt changes in shallow lakes and ponds are not consistently observed and considerable uncertainty remains regarding the ecological and environmental conditions that render these systems susceptible to sudden changes. To address this knowledge gap, we are conducting a mesocosm experiment to quantify how different community configurations and environmental pressures influence the susceptibility of ponds to critical transitions. This research tests the hypothesis that macrophyte density and the rate of external nutrient loading alter the trajectory of phytoplankton dynamics, thus influencing the transition to a turbid state. We supplied 18 mesocosms with field-collected sediment, phytoplankton, zooplankton and fish, and exposed them to three levels of macrophyte densities and two external nutrient loading regimes. Based on daily measurements of phytoplankton biomass (measured as chlorophyll a), we will apply early warning metrics for identifying critical transitions (e.g., http://www.early-warning-signals.org). Our preliminary results indicate that ponds with no macrophytes and the faster nutrient loading rate yield the greatest rate of increase in chlorophyll a. Key goals of this experiment are to enhance the mechanistic understanding of shallow lake and pond dynamics, and aid in the interpretation of lake sediment records as archives of historical critical transitions.

  17. An optimized SYBR Green I/PI assay for rapid viability assessment and antibiotic susceptibility testing for Borrelia burgdorferi.

    PubMed

    Feng, Jie; Wang, Ting; Zhang, Shuo; Shi, Wanliang; Zhang, Ying

    2014-01-01

    Lyme disease caused by Borrelia burgdorferi is the most common tick-borne disease in the US and Europe. Unlike most bacteria, measurements of growth and viability of B. burgdorferi are challenging. The current B. burgdorferi viability assays based on microscopic counting and PCR are cumbersome and tedious and cannot be used in a high throughput format. Here, we evaluated several commonly used viability assays including MTT and XTT assays, fluorescein diacetate assay, Sytox Green/Hoechst 33342 assay, the commercially available LIVE/DEAD BacLight assay, and SYBR Green I/PI assay by microscopic counting and by automated 96-well plate reader for rapid viability assessment of B. burgdorferi. We found that the optimized SYBR Green I/PI assay based on green to red fluorescence ratio is superior to all the other assays for measuring the viability of B. burgdorferi in terms of sensitivity, accuracy, reliability, and speed in automated 96-well plate format and in comparison with microscopic counting. The BSK-H medium which produced a high background for the LIVE/DEAD BacLight assay did not affect the SYBR Green I/PI assay, and the viability of B. burgdorferi culture could be directly measured using a microtiter plate reader. The SYBR Green I/PI assay was found to reliably assess the viability of planktonic as well as biofilm B. burgdorferi and could be used as a rapid antibiotic susceptibility test. Thus, the SYBR Green I/PI assay provides a more sensitive, rapid and convenient method for evaluating viability and antibiotic susceptibility of B. burgdorferi and can be used for high-throughput drug screens.

  18. Development of gemifloxacin in vitro susceptibility test methods for gonococci including quality control guidelines. The Quality Control Study Group.

    PubMed

    Jones, R N; Erwin, M E

    2000-07-01

    Gemifloxacin (formerly SB-265805 or LB20304a) is a new fluoronapthyridone with documented activity against Gram-positive and -negative organisms. The activity of gemifloxacin was tested against 150 Neisseria gonorrhoeae strains, using reference agar dilution, standardized disk diffusion, and Etest (AB BIODISK, Solna, Sweden) methods. Gemifloxacin was very potent against ciprofloxacin (CIPRO)-susceptible strains (MIC(90,) 0.008 microg/ml) but was significantly less active against the CIPRO-resistant gonococci (MIC(90,) 0.12 microg/ml). Etest and reference agar dilution MIC results showed excellent correlation (r = 0.96), and 98.7% MICs were within +/- one log(2) dilution. Agar dilution MICs were also compared to zone diameters obtained using gemifloxacin 5-microg disks; and complete intermethod categorical agreement (100%) was achieved applying breakpoints proposed as follows: < or =0.25 microg/ml (zone, > or =25 mm) for susceptible and > or =1 microg/ml (zone, < or =21 mm) for resistant. Gemifloxacin MIC and disk diffusion te quality control (QC) ranges were established for N. gonorrhoeae ATCC 49226. Data were collected from > or = seven laboratories, three GC agar medium lots for both agar MICs and disk methods, and two lots each of the 5- and 10-microg disks. The proposed MIC QC range was 0.002 to 0.016 microg/ml and the calculated mm zone ranges (median +/- 0.5x average mm range) for both disks were similar, but contained only 88.1 to 91.9% of participant results. To achieve the acceptable > or = 95% of all study results within range, a 43 to 54 mm limits (5-microg disks) were necessary. The excellent broad-spectrum activity and a low reported adverse effects profile of gemifloxacin shows a potential for treatment of fluoroquinolone-resistant gonorrhea.

  19. The susceptibility of the Rorschach Inkblot Test to malingering of combat-related PTSD.

    PubMed

    Frueh, B C; Kinder, B N

    1994-04-01

    The ability of subjects to alter their responses on the Rorschach and self-report measures to fake the symptoms of combat-related Posttraumatic Stress Disorder (PTSD) was investigated. Subjects were 40 White male undergraduates, randomly assigned to either a control or role-informed malingerer group, and 20 White Vietnam veterans with PTSD. Subjects were administered the Rorschach, MMPI-2 validity scales, and Mississippi Scale for Combat-Related PTSD. Results indicated that malingerers were able to achieve scores similar to the PTSD patients on the Mississippi Scale and some Rorschach variables. However, they evidenced significant differences on the MMPI-2 validity scales and several important Rorschach variables. Malingerers typically gave responses that were overly dramatic and less complicated, less emotionally restrained, and indicated an exaggerated sense of impaired reality testing as compared to PTSD patients. Behavioral differences were also noted between the groups. Findings are discussed in the context of the study's limitations and the practical detection of malingered PTSD in clinical settings.

  20. Disrupted-in-schizophrenia 1 (DISC1) plays essential roles in mitochondria in collaboration with Mitofilin

    PubMed Central

    Park, Young-Un; Jeong, Jaehoon; Lee, Haeryun; Mun, Ji Young; Kim, Joung-Hun; Lee, Jong Seo; Nguyen, Minh Dang; Han, Sung Sik; Suh, Pann-Ghill; Park, Sang Ki

    2010-01-01

    Disrupted-in-schizophrenia 1 (DISC1) has emerged as a schizophrenia-susceptibility gene affecting various neuronal functions. In this study, we characterized Mitofilin, a mitochondrial inner membrane protein, as a mediator of the mitochondrial function of DISC1. A fraction of DISC1 was localized to the inside of mitochondria and directly interacts with Mitofilin. A reduction in DISC1 function induced mitochondrial dysfunction, evidenced by decreased mitochondrial NADH dehydrogenase activities, reduced cellular ATP contents, and perturbed mitochondrial Ca2+ dynamics. In addition, deficiencies in DISC1 and Mitofilin induced a reduction in mitochondrial monoamine oxidase-A activity. The mitochondrial dysfunctions evoked by the deficiency of DISC1 were partially phenocopied by an overexpression of truncated DISC1 that is associated with schizophrenia in human. DISC1 deficiencies induced the ubiquitination of Mitofilin, suggesting that DISC1 is critical for the stability of Mitofilin. Finally, the mitochondrial dysfunction induced by DISC1 deficiency was partially reversed by coexpression of Mitofilin, confirming a functional link between DISC1 and Mitofilin for the normal mitochondrial function. According to these results, we propose that DISC1 plays essential roles for mitochondrial function in collaboration with a mitochondrial interacting partner, Mitofilin. PMID:20880836

  1. Kirby-Bauer disc approximation to detect inducible third-generation cephalosporin resistance in Enterobacteriaceae.

    PubMed

    Qin, Xuan; Weissman, Scott J; Chesnut, Mary Frances; Zhang, Bei; Shen, Lisong

    2004-07-15

    Resistance to beta-lactam antibiotics in enteric Gram-negative bacilli may be difficult to detect using standard methods of either Kirby-Bauer disc diffusion (KBDD) or broth dilution for minimal inhibitory concentration (MIC). This difficulty is due to genetic differences in resistance determinants, differences in levels of gene expression, and variation in spectra of enzymatic activity against the substrate beta-lactams used for susceptibility testing. We have examined 95 clinical isolates reportedly susceptible to ceftazidime and ceftriaxone, as originally determined by either KBDD or MIC methods. The organisms studied here were isolated in 2002 from two pediatric hospital centers (Seattle, USA and Shanghai, China). They belong to the inducible beta-lactamase producing Gram-negative bacilli, such as Enterobacter spp., Citrobacter spp., Serratia spp., Morganella spp., Providencia spp., and Proteus vulgaris. A Kirby-Bauer disc approximation (KBDA) method identified inducible phenotypes of third-generation cephalosporin resistance in 76% of isolates, which would otherwise be considered susceptible by standard KBDD methods.

  2. Evaluation of susceptibility test breakpoints used to predict mecA-mediated resistance in Staphylococcus pseudintermedius isolated from dogs.

    PubMed

    Bemis, David A; Jones, Rebekah D; Frank, Linda A; Kania, Stephen A

    2009-01-01

    Clinical and Laboratory Standards Institute interpretive breakpoints for in vitro susceptibility tests that predict mecA-mediated oxacillin resistance in Staphylococcus pseudintermedius isolates from animals have been changed twice in the past decade. Moreover, there are no counterpart recommendations for human isolates of S. pseudintermedius. Individual medical and veterinary laboratories variably use interpretive breakpoints identical to those recommended for use with Staphylococcus aureus or identical to those recommended for use with coagulase-negative staphylococci. The purpose of the current study was to examine correlations between oxacillin disk diffusion, oxacillin gradient diffusion, oxacillin microbroth dilution, and cefoxitin disk diffusion tests used to predict mecA-mediated resistance in S. pseudintermedius and to retrospectively estimate, from disk diffusion zone diameter measurements, the prevalence and rate of increase of oxacillin resistance among canine S. pseudintermedius isolates submitted to a veterinary teaching hospital laboratory. Oxacillin disk diffusion zone diameters of or=0.5 microg/ml were highly correlated with detection of mecA in canine S. pseudintermedius isolates by polymerase chain reaction. MecA-mediated resistance among S. pseudintermedius isolates from dogs increased from less than 5% in 2001 to near 30% in 2007. More than 90% of the methicillin-resistant S. pseudintermedius isolates in 2006 and 2007 were also resistant to representatives of >or=4 additional antimicrobial drug classes. Cefoxitin disk diffusion with the resistance breakpoint set at

  3. A Novel Microfluidic Assay for Rapid Phenotypic Antibiotic Susceptibility Testing of Bacteria Detected in Clinical Blood Cultures

    PubMed Central

    Spaak, Johanna; Cars, Otto; Tängdén, Thomas; Lagerbäck, Pernilla

    2016-01-01

    Background Appropriate antibiotic therapy is critical in the management of severe sepsis and septic shock to reduce mortality, morbidity and health costs. New methods for rapid antibiotic susceptibility testing are needed because of increasing resistance rates to standard treatment. Aims The purpose of this study was to evaluate the performance of a novel microfluidic method and the potential to directly apply this method on positive blood cultures. Methods Minimum inhibitory concentrations (MICs) of ciprofloxacin, ceftazidime, tigecycline and/or vancomycin for Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae and Staphylococcus aureus were determined using a linear antibiotic concentration gradient in a microfluidic assay. Bacterial growth along the antibiotic gradient was monitored using automated time-lapse photomicrography and growth inhibition was quantified by measuring greyscale intensity changes in the images. In addition to pure culture MICs, vancomycin MICs were determined for S. aureus from spiked and clinical blood cultures following a short centrifugation step. The MICs were compared with those obtained with the Etest and for S. aureus and vancomycin also with macrodilution. Results The MICs obtained with the microfluidic assay showed good agreement internally as well as with the Etest and macrodilution assays, although some minor differences were noted between the methods. The time to possible readout was within the range of 2 to 5 h. Conclusions The examined microfluidic assay has the potential to provide rapid and accurate MICs using samples from positive clinical blood cultures and will now be tested using other bacterial species and antibiotics. PMID:27974860

  4. Performance of Vitek 2 for Antimicrobial Susceptibility Testing of Enterobacteriaceae with Vitek 2 (2009 FDA) and 2014 CLSI Breakpoints

    PubMed Central

    Bobenchik, April M.; Deak, Eszter; Hindler, Janet A.; Charlton, Carmen L.

    2014-01-01

    Vitek 2 (bioMérieux Inc., Durham, NC) is a widely used commercial antimicrobial susceptibility test system. We compared the MIC results obtained using the Vitek 2 AST-GN69 and AST-XN06 cards to those obtained by CLSI broth microdilution (BMD) for 255 isolates of Enterobacteriaceae, including 25 isolates of carbapenem-resistant Enterobacteriaceae. In total, 25 antimicrobial agents were examined. For 10 agents, the MIC data were evaluated using two sets of breakpoints: (i) the Vitek 2 breakpoints, which utilized the 2009 FDA breakpoints at the time of the study and are equivalent to the 2009 CLSI M100-S19 breakpoints, and (ii) the 2014 CLSI M100-S24 breakpoints. There was an overall 98.7% essential agreement (EA). The categorical agreement was 95.5% (CA) using the Vitek 2 breakpoints and 95.7% using the CLSI breakpoints. There was 1 very major error (VME) (0.05%) observed using the Vitek 2 breakpoints (cefazolin) and 8 VMEs (0.5%) using the CLSI breakpoints (2 each for aztreonam, cefepime, and ceftriaxone, and 1 for cefazolin and ceftazidime). Fifteen major errors (MEs) (0.4%) were noted using the Vitek 2 breakpoints and 8 (0.5%) using the CLSI breakpoints. Overall, the Vitek 2 performance was comparable to that of BMD for testing a limited number of Enterobacteriaceae commonly isolated by clinical laboratories. Ongoing studies are warranted to assess performance in isolates with emerging resistance. PMID:25540403

  5. Analytic laboratory performance of a point of care urine culture kit for diagnosis and antibiotic susceptibility testing.

    PubMed

    Bongard, E; Frimodt-Møller, N; Gal, M; Wootton, M; Howe, R; Francis, N; Goossens, H; Butler, C C

    2015-10-01

    Currently available point-of-care (POC) diagnostic tests for managing urinary tract infections (UTIs) in general practice are limited by poor performance characteristics, and laboratory culture generally provides results only after a few days. This laboratory evaluation compared the analytic performance of the POC UK Flexicult(™) (Statens Serum Institut) (SSI) urinary kit for quantification, identification and antibiotic susceptibility testing and routine UK National Health Service (NHS) urine processing to an advanced urine culture method. Two hundred urine samples routinely submitted to the Public Health Wales Microbiology Laboratory were divided and: (1) analysed by routine NHS microbiological tests as per local laboratory standard operating procedures, (2) inoculated onto the UK Flexicult(™) SSI urinary kit and (3) spiral plated onto Colorex Orientation UTI medium (E&O Laboratories Ltd). The results were evaluated between the NHS and Flexicult(™ )methods, and discordant results were compared to the spiral plating method. The UK Flexicult(™) SSI urinary kit was compared to routine NHS culture for identification of a pure or predominant uropathogen at ≥ 10(5) cfu/mL, with a positive discordancy rate of 13.5% and a negative discordancy rate of 3%. The sensitivity and specificity were 86.7% [95% confidence interval (CI) 73.8-93.7] and 82.6% (95% CI 75.8-87.7), respectively. The UK Flexicult(™) SSI urinary kit was comparable to routine NHS urine processing in identifying microbiologically positive UTIs in this laboratory evaluation. However, the number of false-positive samples could lead to over-prescribing of antibiotics in clinical practice. The Flexicult(™) SSI kit could be useful as a POC test for UTIs in primary care but further pragmatic evaluations are necessary.

  6. The high-throughput phenotyping of the viscoelastic behavior of whole mouse intervertebral discs using a novel method of dynamic mechanical testing.

    PubMed

    Liu, Jennifer W; Abraham, Adam C; Tang, Simon Y

    2015-07-16

    Intervertebral disc (IVD) degeneration is highly correlated with lower back pain, and thus understanding the mechanisms of IVD degeneration is critical for the treatment of this disease. Utilizing mouse models to probe the mechanisms of degeneration is especially attractive due to the ease of manipulating mouse models and the availability of transgenics. Yet characterizing the mechanical behavior of mice IVDs remain challenging due to their minute size (approximately 540 μm in height and 1080 μm(2) in cross sectional area). We have thus developed a simple method to dynamically characterize the mechanical properties of intact mouse IVDs. The IVDs were dissected with the endplates intact, and dynamically compressed in the axial direction at 1% and 5% peak strains at 1 Hz. Utilizing this novel approach, we examined the effects of in vitro ribosylation and trypsin digestion for 24 or 72 h on the viscoelastic behavior of the whole murine IVD. Trypsin treatment resulted in a decrease of proteoglycans and loss of disc height, while ribosylation had no effect on structure or proteoglycan composition. The 72 h ribosylation group exhibited a stiffening of the disc, and both treatments significantly reduced viscous behavior of the IVDs, with the effects being more pronounced at 5% strain. Here we demonstrate a novel high-throughput method to mechanically characterize murine IVDs and detect strain-dependent differences in the elastic and the viscous behavior of the treated IVDs due to ribose and trypsin treatments.

  7. Microbial identification and automated antibiotic susceptibility testing directly from positive blood cultures using MALDI-TOF MS and VITEK 2.

    PubMed

    Wattal, C; Oberoi, J K

    2016-01-01

    The study addresses the utility of Matrix Assisted Laser Desorption/Ionisation Time-Of-Flight mass spectrometry (MALDI-TOF MS) using VITEK MS and the VITEK 2 antimicrobial susceptibility testing (AST) system for direct identification (ID) and timely AST from positive blood culture bottles using a lysis-filtration method (LFM). Between July and December 2014, a total of 140 non-duplicate mono-microbial blood cultures were processed. An aliquot of positive blood culture broth was incubated with lysis buffer before the bacteria were filtered and washed. Micro-organisms recovered from the filter were first identified using VITEK MS and its suspension was used for direct AST by VITEK 2 once the ID was known. Direct ID and AST results were compared with classical methods using solid growth. Out of the 140 bottles tested, VITEK MS resulted in 70.7 % correct identification to the genus and/ or species level. For the 103 bottles where identification was possible, there was agreement in 97 samples (94.17 %) with classical culture. Compared to the routine method, the direct AST resulted in category agreement in 860 (96.5 %) of 891 bacteria-antimicrobial agent combinations tested. The results of direct ID and AST were available 16.1 hours before those of the standard approach on average. The combined use of VITEK MS and VITEK 2 directly on samples from positive blood culture bottles using a LFM technique can result in rapid and reliable ID and AST results in blood stream infections to result in early institution of targeted treatment. The combination of LFM and AST using VITEK 2 was found to expedite AST more reliably.

  8. Evaluation by the Double Loop Electrochemical Potentiokinetic Reactivation Test of Aged Ferritic Stainless Steel Intergranular Corrosion Susceptibility

    NASA Astrophysics Data System (ADS)

    Sidhom, H.; Amadou, T.; Braham, C.

    2010-12-01

    An experimental design method was used to determine the effect of factors that significantly affect the response of the double loop-electrochemical potentiokinetic reactivation (DL-EPR) test in controlling the susceptibility to intergranular corrosion (IGC) of UNS S43000 (AISI 430) ferritic stainless steel. The test response is expressed in terms of the reactivation/activation current ratio ( I r / I a pct). Test results analysed by the analysis of variance (ANOVA) method show that the molarity of the H2SO4 electrolyte and the potential scanning rate have a more significant effect on the DL-EPR test response than the temperature and the depassivator agent concentration. On the basis of these results, a study was conducted in order to determine the optimal operating conditions of the test as a nondestructive technique for evaluating IGC resistance of ferritic stainless steel components. Three different heat treatments are considered in this study: solution annealing (nonsensitized), aging during 3 hours at 773 K (500 °C) (slightly sensitized), and aging during 2 hours at 873 K (600 °C) (highly sensitized). The aim is to find the operating conditions that simultaneously ensure the selectivity of the attack (intergranular and chromium depleted zone) and are able to detect the effect of low dechromization. It is found that a potential scanning rate of 2.5 mV/s in an electrolyte composed of H2SO4 3 M solution without depassivator, at a temperature around 293 K (20 °C), is the optimal operating condition for the DL-EPR test. Using this condition, it is possible to assess the degree of sensitization (DOS) to the IGC of products manufactured in ferritic stainless steels rapidly, reliably, and quantitatively. A time-temperature-start of sensitization (TTS) diagram for the UNS S43000 (France Inox, Villepinte, France) stainless steel was obtained with acceptable accuracy by this method when the IGC sensitization criterion was set to I r / I a > 1 pct. This diagram is in

  9. The origin of thick discs

    NASA Astrophysics Data System (ADS)

    Comerón, Sébastien

    2015-03-01

    Thick discs are defined to be disc-like components with a scale height larger than that of the classical discs. They are ubiquitous (Yoachim & Dalcanton 2006; Comerón et al. 2011a), they are made of mostly old and metal-poor stars and are most easily detected in close to edge-on galaxies. Their origin has been considered mysterious and several formation theories have been proposed: • The thick disc being formed secularly by thin disc stars heated by disc overdensities such as giant molecular clouds or spiral arms (Villumsen 1985, ApJ, 290, 75) and by stars moved outwards from their original orbits by radial migration mechanisms (Schönrich & Binney 2009). • The thick disc being formed by the heating of the thin disc by satellites (Quinn et al. 1993) and the tidal stripping of them (Abadi et al. 2003). • The thick disc being formed fast and already thick at high redshift in an highly unstable disc. Inside that thick disc, a thin disc would form afterwards as suggested by Elemgreen & Elmegreen (2006). • The thick disc being formed originally thick at high redshift by the merger of gas-rich protogalactic fragments and a thin disc forming afterwards within it (Brook et al. 2007). The first mechanism is a secular evolution mechanism. The time-scale of the second one is dependent on the merger history of the main galaxy. In the two last mechanisms, the thick disc forms already thick in a short time-scale at high redshift. Recent Milky Way studies, (see, e.g., Bovy et al. 2012), have shown indications that there is no discontinuity between the thin and the thick disc chemical and kinematic properties. Instead, those studies indicate the presence of a monotonic distribution of disc thicknesses. This would suggest a secular origin for the Milky Way thick disc. Studies in external galaxies (Yoachim & Dalcanton 2006; Comerón et al. 2011b), have shown that low-mass disc galaxies have thick disc relative masses much larger than those found in large-mass galaxies

  10. Susceptibility Test Safety Margin

    NASA Astrophysics Data System (ADS)

    Audone, B.; Marziali, I.; Nicoletto, M.; Boschetti, D.

    2016-05-01

    The paper presents a novel approach to relate the probability of malfunction of an EUT to the emission profile of the electromagnetic environment where the EUT is going to be installed. The proposed algorithm calculates the probability of malfunction at each frequency for both steady state signals and transient signals and then the overall probability of malfunction per number of frequencies.

  11. Second line drug susceptibility testing to inform the treatment of rifampin-resistant tuberculosis: a quantitative perspective.

    PubMed

    Kendall, Emily A; Cohen, Ted; Mitnick, Carole D; Dowdy, David W

    2017-03-01

    Treatment failure and resistance amplification are common among patients with rifampin-resistant tuberculosis (TB). Drug susceptibility testing (DST) for second-line drugs is recommended for these patients, but logistical difficulties have impeded widespread implementation of second-line DST in many settings. To provide a quantitative perspective on the decision to scale up second-line DST, we synthesize literature on the prevalence of second-line drug resistance, the expected clinical and epidemiologic benefits of using second-line DST to ensure that patients with rifampin-resistant TB receive effective regimens, and the costs of implementing (or not implementing) second-line DST for all individuals diagnosed with rifampin-resistant TB. We conclude that, in most settings, second-line DST could substantially improve treatment outcomes for patients with rifampin-resistant TB, reduce transmission of drug-resistant TB, prevent amplification of drug resistance, and be affordable or even cost-saving. Given the large investment made in each patient treated for rifampin-resistant TB, these payoffs would come at relatively small incremental cost. These anticipated benefits likely justify addressing the real challenges faced in implementing second-line DST in most high-burden settings.

  12. Genetic diversity of Aspergillus species isolated from onychomycosis and Aspergillus hongkongensis sp. nov., with implications to antifungal susceptibility testing.

    PubMed

    Tsang, Chi-Ching; Hui, Teresa W S; Lee, Kim-Chung; Chen, Jonathan H K; Ngan, Antonio H Y; Tam, Emily W T; Chan, Jasper F W; Wu, Andrea L; Cheung, Mei; Tse, Brian P H; Wu, Alan K L; Lai, Christopher K C; Tsang, Dominic N C; Que, Tak-Lun; Lam, Ching-Wan; Yuen, Kwok-Yung; Lau, Susanna K P; Woo, Patrick C Y

    2016-02-01

    Thirteen Aspergillus isolates recovered from nails of 13 patients (fingernails, n=2; toenails, n=11) with onychomycosis were characterized. Twelve strains were identified by multilocus sequencing as Aspergillus spp. (Aspergillus sydowii [n=4], Aspergillus welwitschiae [n=3], Aspergillus terreus [n=2], Aspergillus flavus [n=1], Aspergillus tubingensis [n=1], and Aspergillus unguis [n=1]). Isolates of A. terreus, A. flavus, and A. unguis were also identifiable by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The 13th isolate (HKU49(T)) possessed unique morphological characteristics different from other Aspergillus spp. Molecular characterization also unambiguously showed that HKU49(T) was distinct from other Aspergillus spp. We propose the novel species Aspergillus hongkongensis to describe this previously unknown fungus. Antifungal susceptibility testing showed most Aspergillus isolates had low MICs against itraconazole and voriconazole, but all Aspergillus isolates had high MICs against fluconazole. A diverse spectrum of Aspergillus species is associated with onychomycosis. Itraconazole and voriconazole are probably better drug options for Aspergillus onychomycosis.

  13. Accuracy of the VITEK® 2 system for a rapid and direct identification and susceptibility testing of Gramnegative rods and Gram-positive cocci in blood samples.

    PubMed

    Nimer, N A; Al-Saa'da, R J; Abuelaish, O

    2016-06-15

    The performance of the VITEK® 2 system for direct rapid identification and antimicrobial susceptibility testing of the bacteria responsible for blood infections was determined. The isolates studied included 166 Gram-negative rods and 74 Gram-positive cocci from inpatients. Specially treated monomicrobial samples from positive blood culture bottles were directly inoculated into the VITEK 2 system and the results were compared with those from cards inoculated with standardized bacterial suspensions. Compared with the standard method, 95.8% of Gram-negative rods were correctly identified by VITEK 2 and the overall level of agreement between the two methods in susceptibility testing was 92.0%. For Gram-positive bacteria, 89.2% were correctly identified by VITEK 2 and susceptibility testing revealed an overall agreement rate of 91.3%. These results suggest that VITEK 2 cards inoculated with fluids sampled directly from positive blood culture bottles are suitable for speedy identification and susceptibility testing of Gram-negative bacilli and Gram-positive cocci.

  14. Acceleration of antimicrobial susceptibility testing of positive blood cultures by inoculation of Vitek 2 cards with briefly incubated solid medium cultures.

    PubMed

    Idelevich, Evgeny A; Schüle, Isabel; Grünastel, Barbara; Wüllenweber, Jörg; Peters, Georg; Becker, Karsten

    2014-11-01

    Briefly incubated agar cultures from positive blood cultures were used for antimicrobial susceptibility testing (AST) by Vitek 2. The cultivation time until inoculation was 3.8 h for Gram-positive cocci and 2.4 h for Gram-negative rods. The error rates were low, providing early and reliable AST without additional time or cost expenditure.

  15. Susceptibility Testing by Polymerase Chain Reaction DNA Quantitation: A Method to Measure Drug Resistance of Human Immunodeficiency Virus Type 1 Isolates

    NASA Astrophysics Data System (ADS)

    Eron, Joseph J.; Gorczyca, Paul; Kaplan, Joan C.; D'Aquila, Richard T.

    1992-04-01

    Polymerase chain reaction (PCR) DNA quantitation (PDQ) susceptibility testing rapidly and directly measures nucleoside sensitivity of human immunodeficiency virus type 1 (HIV-1) isolates. PCR is used to quantitate the amount of HIV-1 DNA synthesized after in vitro infection of peripheral blood mononuclear cells. The relative amounts of HIV-1 DNA in cell lysates from cultures maintained at different drug concentrations reflect drug inhibition of virus replication. The results of PDQ susceptibility testing of 2- or 3-day cultures are supported by assays measuring HIV-1 p24 antigen production in supernatants of 7- or 10-day cultures. DNA sequence analyses to identify mutations in the reverse transcriptase gene that cause resistance to 3'-azido-3'-deoxythymidine also support the PDQ results. With the PDQ method, both infectivity titration and susceptibility testing can be performed on supernatants from primary cultures of peripheral blood mononuclear cells. PDQ susceptibility testing should facilitate epidemiologic studies of the clinical significance of drug-resistant HIV-1 isolates.

  16. Novel Method Based on Real-Time Cell Analysis for Drug Susceptibility Testing of Herpes Simplex Virus and Human Cytomegalovirus

    PubMed Central

    Piret, Jocelyne; Goyette, Nathalie

    2016-01-01

    The plaque reduction assay (PRA) is the gold standard phenotypic method to determine herpes simplex virus (HSV) and human cytomegalovirus (HCMV) susceptibilities to antiviral drugs. However, this assay is subjective and labor intensive. Here, we describe a novel antiviral phenotypic method based on real-time cell analysis (RTCA) that measures electronic impedance over time. The effective drug concentrations that reduced by 50% (EC50s) the cytopathic effects induced by HSV-1 and HCMV were evaluated by both methods. The EC50s of acyclovir and foscarnet against a reference wild-type (WT) HSV-1 strain in Vero cells were, respectively, 0.5 μM and 32.6 μM by PRA and 0.8 μM and 93.6 μM by RTCA. The EC50 ratios for acyclovir against several HSV-1 thymidine kinase (TK) mutants were 101.8×, 73.4×, 28.8×, and 35.4× (PRA) and 18.0×, 52.0×, 5.5×, and 87.8× (RTCA) compared to those for the WT. The EC50 ratios for acyclovir and foscarnet against the HSV-1 TK/DNA polymerase mutant were 182.8× and 9.7× (PRA) and >125.0× and 10.8× (RTCA) compared to the WT. The EC50s of ganciclovir and foscarnet against WT HCMV strain AD169 in fibroblasts were, respectively, 1.6 μM and 27.8 μM by PRA and 5.0 μM and 111.4 μM by RTCA. The EC50 ratios of ganciclovir against the HCMV UL97 mutant were 3.8× (PRA) and 8.2× (RTCA) compared to those for the WT. The EC50 ratios of ganciclovir and foscarnet against the HCMV UL97/DNA polymerase mutant were 17.1× and 12.1× (PRA) and 14.7× and 4.6× (RTCA) compared to those for the WT. RTCA allows objective drug susceptibility testing of HSV and HCMV and could permit high-throughput screening of new antivirals. PMID:27252463

  17. Comparison of BD phoenix to vitek 2, microscan MICroSTREP, and Etest for antimicrobial susceptibility testing of Streptococcus pneumoniae.

    PubMed

    Mittman, Scott A; Huard, Richard C; Della-Latta, Phyllis; Whittier, Susan

    2009-11-01

    The performance of the BD Phoenix Automated Microbiology System (BD Diagnostic Systems) was compared to those of the Vitek 2 (bioMérieux), the MicroScan MICroSTREP plus (Siemens), and Etest (bioMérieux) for antibiotic susceptibility tests (AST) of 311 clinical isolates of Streptococcus pneumoniae. The overall essential agreement (EA) between each test system and the reference microdilution broth reference method for S. pneumoniae AST results was >95%. For Phoenix, the EAs of individual antimicrobial agents ranged from 90.4% (clindamycin) to 100% (vancomycin and gatifloxacin). The categorical agreements (CA) of Phoenix, Vitek 2, MicroScan, and Etest for penicillin were 95.5%, 94.2%, 98.7%, and 97.7%, respectively. The overall CA for Phoenix was 99.3% (1 very major error [VME] and 29 minor errors [mEs]), that for Vitek 2 was 98.8% (7 VMEs and 28 mEs), and those for MicroScan and Etest were 99.5% each (19 and 13 mEs, respectively). The average times to results for Phoenix, Vitek 2, and the manual methods were 12.1 h, 9.8 h, and 24 h, respectively. From these data, the Phoenix AST results demonstrated a high degree of agreement with all systems evaluated, although fewer VMEs were observed with the Phoenix than with the Vitek 2. Overall, both automated systems provided reliable AST results for the S. pneumoniae-antibiotic combinations in half the time required for the manual methods, rendering them more suitable for the demands of expedited reporting in the clinical setting.

  18. A test system to evaluate the susceptibility of Oregon, USA, native stream invertebrataes to triclopyr and carbaryl.

    PubMed

    Peterson, J L; Jepson, P C; Jenkins, J J

    2001-10-01

    The susceptibility of six indigenous macroinvertebrate species representative of U.S. Pacific Northwest streams (Ameletus sp., Brachycentrus americanus, Calineuria californica, Cinygma sp., Lepidostoma unicolor, Psychoglypha sp. early and late instar) to formulated triclopyr ester (herbicide) and carbaryl (insecticide) was determined using laboratory bioassays. Acute toxicity was expressed as the lethal concentration to 50% (LC50) and 1% (LC1) of the test population based on a 96-h exposure duration. Carbaryl was found to be 1,000 times more toxic than triclopyr for all the organisms tested. The LCI values (7.5, 28.8, 9.0, 3.0, 9.5, 14.8, 33.8 microg/L, respectively, for carbaryl and 1.8, 3.9, 4.0, 4.2, 29.0, 16.1 mg/L, respectively, for triclopyr) were used in the calculation of hazardous concentration to 5% of the stream macroinvertebrate community (HC5) based on the lower 95% confidence limit (HC5/95). The hazardous concentration (HC5/95) for triclopyr was 0.11 mg/L and for carbaryl ranged from 0.43 to 0.66 microg/L, respectively. Triclopyr and carbaryl symptomology were analyzed for two organisms, C. californica and Cinygma sp. Carbaryl symptomology included knockdown and moribund states with severity and time of appearance being a function of dose. In triclopyr poisoning, death occurred suddenly with little or no symptomology. Time to 50% mortality (LT50) values were consistently higher for C. californica than for Cinygma sp. exposed to both chemicals at similar concentrations.

  19. The Galactic stellar disc

    NASA Astrophysics Data System (ADS)

    Feltzing, S.; Bensby, T.

    2008-12-01

    The study of the Milky Way stellar discs in the context of galaxy formation is discussed. In particular, we explore the properties of the Milky Way disc using a new sample of about 550 dwarf stars for which we have recently obtained elemental abundances and ages based on high-resolution spectroscopy. For all the stars we also have full kinematic information as well as information about their stellar orbits. We confirm results from previous studies that the thin and the thick discs have distinct abundance patterns. But we also explore a larger range of orbital parameters than what has been possible in our previous studies. Several new results are presented. We find that stars that reach high above the Galactic plane and have eccentric orbits show remarkably tight abundance trends. This implies that these stars formed out of well-mixed gas that had been homogenized over large volumes. We find some evidence that suggest that the event that most likely caused the heating of this stellar population happened a few billion years ago. Through a simple, kinematic exploration of stars with super-solar [Fe/H], we show that the solar neighbourhood contains metal-rich, high velocity stars that are very likely associated with the thick disc. Additionally, the HR1614 moving group and the Hercules and Arcturus stellar streams are discussed and it is concluded that, probably, a large fraction of the groups and streams so far identified in the disc are the result of evolution and interactions within the stellar disc rather than being dissolved stellar clusters or engulfed dwarf galaxies. This paper includes data gathered with the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile. Also based on observations collected at the Nordic Optical Telescope on La Palma, Spain, and at the European Southern Observatories on La Silla and Paranal, Chile, Proposals no. 65.L-0019(B), 67.B-0108(B), 69.B-0277.

  20. Observations on macrolide resistance and susceptibility testing performance in field isolates collected from clinical bovine respiratory disease cases

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objectives of this study were; first, to describe gamithromycin susceptibility of Mannheimia haemolytica, Pasteurella multocida, and Histophilus somni isolated from cattle diagnosed with bovine respiratory disease (BRD) and previously treated with either gamithromycin for control of BRD (mass me...

  1. Evaluation of Veterinary-Specific Interpretive Criteria for Susceptibility Testing of Streptococcus equi Subspecies with Trimethoprim-Sulfamethoxazole and Trimethoprim-Sulfadiazine

    PubMed Central

    Kanellos, Theo; Guardabassi, Luca; Boucher, Joseph

    2016-01-01

    ABSTRACT Antimicrobial susceptibility test results for trimethoprim-sulfadiazine with Streptococcus equi subspecies are interpreted based on human data for trimethoprim-sulfamethoxazole. The veterinary-specific data generated in this study support a single breakpoint for testing trimethoprim-sulfamethoxazole and/or trimethoprim-sulfadiazine with S. equi. This study indicates trimethoprim-sulfamethoxazole as an acceptable surrogate for trimethoprim-sulfadiazine with S. equi. PMID:27847375

  2. Comparative evaluation of Vitek 2 identification and susceptibility testing of Gram-negative rods directly and isolated from BacT/ALERT-positive blood culture bottles.

    PubMed

    Munoz-Dávila, M J; Yagüe, G; Albert, M; García-Lucas, T

    2012-05-01

    The performance of Vitek 2 was evaluated for the identification and susceptibility testing of Gram-negative bacilli directly from positive blood cultures bottles. Direct inoculation of the positive blood cultures with the Vitek cards ID-GN and AST-NO58 was compared with the standard inoculation method based on the sub-culture of the positive blood culture to agar. A total of 142 blood cultures were included in the study; of those, 119 were from patients' clinical samples, while 23 were artificially prepared with strains showing different mechanisms of resistance. A total of 136 (95.8%) strains were correctly identified to the species level, only 2 (1.4%) were mis-identified and 4 (2.8%) were not identified. Susceptibility results were available for all isolates tested against 17 antibiotics, thus, resulting in a total of 2,414 isolate/anti-microbial combinations. The error rate was 2.8% (67/2,414) overall; 0.6% (14/2,414) very major errors, 0.1% (3/2,414) major errors and 2.1% (50/2,414) minor errors. The direct method detected 88.5% (22/25) of the strains producing extended-spectrum beta-lactamases (ESBLs). The susceptibility agreement among the added strains with ESBL, AMPc hyperproduction, resistance to ceftazidime, carbapenems and cefepime was very high. Direct identification and susceptibility testing gave rapid and reliable results, reducing by 24 h the turnaround time of the microbiology laboratory.

  3. Validation of the MicroScan-96 for the species identification and methicillin susceptibility testing of clinical significant coagulase-negative staphylococci.

    PubMed

    Patteet, L; Goossens, H; Ieven, M

    2012-05-01

    An automated system, MicroScan WalkAway-96, in conjugation with Combo Pos® 28 panels, was validated for the identification and methicillin susceptibility of coagulase-negative staphylococci (CNS). The performance of this system was evaluated on 428 CNS. Identification results were compared using a validated in-house method. Methicillin susceptibility was compared with oxacillin MIC testing and the presence of the mecA gene by PCR (in-house real-time method). The MicroScan system correctly identified 94.6% of the staphylococci (405 out of 428). 3.5% of the strains (15 out of 428) were not correctly identified. 1.9% of the isolates (8 out of 428) were correctly identified with a low probability. Identification of Staphylococcus warneri and Staphylococcus lugdunensis was determined with the least accuracy. Microscan combines both oxacillin and cefoxitin for determination of the methicillin susceptibility result. Correlation between this result and the mecA method was 97.6%. Correlation with the oxacillin MIC method was also 97.6%. Fourteen isolates showed a discrepant result, 8 were reported to be resistant in mecA-negative strains, 2 were reported false-susceptible in mecA positive strains and 4 strains showed a discrepant result with oxacillin MIC, but not with mecA determination. The automated system can be considered a simple and reliable method for identification and methicillin susceptibility of CNS.

  4. Human immunodeficiency virus type 1 drug susceptibility determination by using recombinant viruses generated from patient sera tested in a cell-killing assay.

    PubMed Central

    Boucher, C A; Keulen, W; van Bommel, T; Nijhuis, M; de Jong, D; de Jong, M D; Schipper, P; Back, N K

    1996-01-01

    A simple approach for the determination of drug susceptibilities by using human immunodeficiency virus type 1 (HIV-1) RNA from the sera of patients is described. HIV-1 RNA was extracted from patient sera, and the 5' part of the reverse transcriptase (RT) gene was transcribed into DNA and amplified in a nested PCR. The amplified fragment covers the 3' part of the protease gene and amino acids 1 to 304 of the RT gene. This fragment can be introduced through homologous recombination, as described previously, into a novel HIV-1 reference strain (pHXB2 delta 2-261RT) from which amino acids 2 to 261 of RT have been deleted. The resulting recombinant virus expresses all properties of the HXB2 reference strain except for those encoded by the introduced part of the patient RT gene. Recombinant viruses were subsequently tested for drug susceptibility in a microtiter format killing assay [3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide assay] as well as in the standard HeLa CD4+ plaque reduction assay. Similar susceptibility profiles were obtained by each assay with recombinant viruses derived from patients receiving alternating nevirapine and zidovudine treatment or lamivudine-zidovudine combination therapy. In conclusion, this approach enables high-through-put determination of the drug susceptibilities of serum RNA-derived RT genes, independent of the patient's viral background, and generates the possibility of relating changes in susceptibility to changes in viral genotypes. PMID:8891152

  5. Rapid Identification and Drug Susceptibility Testing of Mycobacterium tuberculosis: Standard Operating Procedure for Non-Commercial Assays: Part 1: Microscopic Observation Drug Susceptibility Assay v2.4.12.

    PubMed

    Singh, Sarman; Kumar, Parveen; Sharma, Shreya; Mumbowa, Francis; Martin, Anandi; Durier, Nicolas

    2012-07-01

    Multidrug-resistant tuberculosis is an increasing public health concern in many parts of the world, especially in low-income countries, where most cases occur. Traditional mycobacteria culture and drug susceptibility testing (DST) is either time-consuming or expensive and for that reason uptake of these technologies has remained limited in many resource-constrained settings. However, several non-commercial culture and DST methods that do not require sophisticated infrastructure and techniques have been developed. One such method is the microscopic observation drug susceptibility assay (MODS). In this method microcolonies that form in the liquid culture medium after specimen inoculation to drug-free and drug-containing micro-wells are detected by visual observation with a simple inverted microscope. The identification and drug susceptibility results can be obtained in 7-15 days. This standard operating procedure document has been developed through the culture and DST subgroup of the STOP TB Partnership, New Diagnostic Working Group. It is intended for laboratories that would want to use or already using this rapid non-commercial method for culture identification and DST of Mycobacterium tuberculosis, notably in resource-constraint settings in Asia and Africa.

  6. Short communication: Heritability estimates for susceptibility to Mycobacterium avium subspecies paratuberculosis infection defined by ELISA and fecal culture test results in Jersey cattle.

    PubMed

    Zare, Y; Shook, G E; Collins, M T; Kirkpatrick, B W

    2014-07-01

    Paratuberculosis (Johne's disease), an enteric disorder in ruminants caused by Mycobacterium avium ssp. paratuberculosis, causes economic losses in excess of $200 million annually to the US dairy industry. Costly diagnostic testing, cumbersome control programs, incurability, and ineffective vaccination all make M. avium ssp. paratuberculosis susceptibility a good candidate for genetic studies and genetic selection a potentially useful adjunct to management-based control programs. No report has been published for heritability of susceptibility to M. avium ssp. paratuberculosis infection in Jersey cattle. The objective of this study was to estimate variance components and heritability for susceptibility to M. avium ssp. paratuberculosis infection in US Jersey cattle. Data consisted of complete serum ELISA and partial fecal culture results on a total of 2,861 Jersey cows from 23 commercial herds throughout the United States after editing. Four M. avium ssp. paratuberculosis susceptibility phenotypes were defined using (1) ELISA sample-to-positive ratios as a continuous trait, (2) ELISA results as a binary trait (positive=1, negative=0), (3) ELISA results as an ordered categorical trait, and (4) a combined test in which ELISA and fecal culture results were both taken into account in a binary analysis. Three statistical models, including linear, binary threshold, and ordered threshold sire models, were used to analyze the data. All analyses were executed using the restricted maximum likelihood method in ASReml 3 software. The heritability estimates were low to moderate and ranged from 0.08 (±0.03) to 0.27 (±0.11) based on different trait definitions. The nonzero heritability indicates that susceptibility to M. avium ssp. paratuberculosis infection in Jersey cattle is influenced by genetic factors. Therefore, selection of the least susceptible animals could decrease genetic predisposition to M. avium ssp. paratuberculosis infection in Jersey populations in future

  7. Educational antimicrobial susceptibility testing as a critical component of microbiology laboratory proficiency programs: American Proficiency Institute results for 2007-2011.

    PubMed

    Jones, Ronald N; Glick, Teri; Sader, Helio S; Flamm, Robert K; Ross, James E; Rhomberg, Paul R; Edson, Daniel C

    2013-04-01

    External laboratory proficiency programs are an important requirement for test quality assurance (EQA) and compliance to regulatory guidelines (Clinical Laboratory Improvement Amendments and inspections). The American Proficiency Institute (API) regularly distributes EQA sample challenges (test events) including an Educational Sample (ES) for antimicrobial susceptibility testing. Beginning in 2007, API has sent 3 ES samples annually, each a well-characterized (molecular/phenotypic methods) strain having an interesting/emerging mechanism of resistance. Hundreds of USA laboratories, usually serving small- to medium-size hospitals and clinics, participate in the API ungraded ES test event. Analysis of responses is made and reported electronically as ES critiques addressing contemporary susceptibility testing issues that affect patient therapy. Seven Gram-positive (+) and 8 Gram-negative (-) ES strains were tested over the 5 years (2007-2011) with organism identification (graded) accuracy of 95.3% (range, 91.0-99.2%) for Gram (-) and 97.0% (range, 94.2-100.0%) for Gram (+) challenges. Susceptibility testing categorical accuracy was generally greatest for the disk diffusion test (91.0/97.0%) compared to the MIC methods (commercial automated or manual) combined (89.9/96.1%, for Gram [-]/Gram [+], respectively). The most worrisome observations of these ES samples were as follows: 1) poor recognition of ESBL- and serine carbapenemase-producing strains (various types including Klebsiella pneumoniae carbapanemase) due to delayed application of Clinical and Laboratory Standards Institute [CLSI] guidelines; 2) overcalling of ESBL in organisms having wild-type non-ESBL enzymes (OXA series; OXA, 1/30) due to commercial system or participant interpretive error; and 3) occasional drug-bug discords noted in nonfermentative Gram (-) bacilli. In conclusion, the API ES series of ungraded susceptibility testing challenges (accuracy was >90%) has been well received by subscribers and

  8. Comparative Evaluation of PASCO and National Committee for Clinical Laboratory Standards M27-A Broth Microdilution Methods for Antifungal Drug Susceptibility Testing of Yeasts

    PubMed Central

    Arthington-Skaggs, Beth A.; Motley, Milwood; Warnock, David W.; Morrison, Christine J.

    2000-01-01

    The PASCO antifungal susceptibility test system, developed in collaboration with a commercial company, is a broth microdilution assay which is faster and easier to use than the reference broth microdilution test performed according to the National Committee for Clinical Laboratory Standards (NCCLS) document M27-A guidelines. Advantages of the PASCO system include the system's inclusion of quality-controlled, premade antifungal panels containing 10, twofold serial dilutions of drugs and a one-step inoculation system whereby all wells are simultaneously inoculated in a single step. For the prototype panel, we chose eight antifungal agents for in vitro testing (amphotericin B, flucytosine, fluconazole, ketoconazole, itraconazole, clotrimazole, miconazole, and terconazole) and compared the results with those of the NCCLS method for testing 74 yeast isolates (14 Candida albicans, 10 Candida glabrata, 10 Candida tropicalis, 10 Candida krusei, 10 Candida dubliniensis, 10 Candida parapsilosis, and 10 Cryptococcus neoformans isolates). The overall agreements between the methods were 91% for fluconazole, 89% for amphotericin B and ketoconazole, 85% for itraconazole, 80% for flucytosine, 77% for terconazole, 66% for miconazole, and 53% for clotrimazole. In contrast to the M27-A reference method, the PASCO method classified as resistant seven itraconazole-susceptible isolates (9%), two fluconazole-susceptible isolates (3%), and three flucytosine-susceptible isolates (4%), representing 12 major errors. In addition, it classified two fluconazole-resistant isolates (3%) and one flucytosine-resistant isolate (1%) as susceptible, representing three very major errors. Overall, the agreement between the methods was greater than or equal to 80% for four of the seven species tested (C. dubliniensis, C. glabrata, C. krusei, and C. neoformans). The lowest agreement between methods was observed for miconazole and clotrimazole and for C. krusei isolates tested against terconazole. When the

  9. Comparative evaluation of PASCO and national committee for clinical laboratory standards M27-A broth microdilution methods for antifungal drug susceptibility testing of yeasts.

    PubMed

    Arthington-Skaggs, B A; Motley, M; Warnock, D W; Morrison, C J

    2000-06-01

    The PASCO antifungal susceptibility test system, developed in collaboration with a commercial company, is a broth microdilution assay which is faster and easier to use than the reference broth microdilution test performed according to the National Committee for Clinical Laboratory Standards (NCCLS) document M27-A guidelines. Advantages of the PASCO system include the system's inclusion of quality-controlled, premade antifungal panels containing 10, twofold serial dilutions of drugs and a one-step inoculation system whereby all wells are simultaneously inoculated in a single step. For the prototype panel, we chose eight antifungal agents for in vitro testing (amphotericin B, flucytosine, fluconazole, ketoconazole, itraconazole, clotrimazole, miconazole, and terconazole) and compared the results with those of the NCCLS method for testing 74 yeast isolates (14 Candida albicans, 10 Candida glabrata, 10 Candida tropicalis, 10 Candida krusei, 10 Candida dubliniensis, 10 Candida parapsilosis, and 10 Cryptococcus neoformans isolates). The overall agreements between the methods were 91% for fluconazole, 89% for amphotericin B and ketoconazole, 85% for itraconazole, 80% for flucytosine, 77% for terconazole, 66% for miconazole, and 53% for clotrimazole. In contrast to the M27-A reference method, the PASCO method classified as resistant seven itraconazole-susceptible isolates (9%), two fluconazole-susceptible isolates (3%), and three flucytosine-susceptible isolates (4%), representing 12 major errors. In addition, it classified two fluconazole-resistant isolates (3%) and one flucytosine-resistant isolate (1%) as susceptible, representing three very major errors. Overall, the agreement between the methods was greater than or equal to 80% for four of the seven species tested (C. dubliniensis, C. glabrata, C. krusei, and C. neoformans). The lowest agreement between methods was observed for miconazole and clotrimazole and for C. krusei isolates tested against terconazole. When the

  10. How do accretion discs break?

    NASA Astrophysics Data System (ADS)

    Dogan, Suzan

    2016-07-01

    Accretion discs are common in binary systems, and they are often found to be misaligned with respect to the binary orbit. The gravitational torque from a companion induces nodal precession in misaligned disc orbits. In this study, we first calculate whether this precession is strong enough to overcome the internal disc torques communicating angular momentum. We compare the disc precession torque with the disc viscous torque to determine whether the disc should warp or break. For typical parameters precession wins: the disc breaks into distinct planes that precess effectively independently. To check our analytical findings, we perform 3D hydrodynamical numerical simulations using the PHANTOM smoothed particle hydrodynamics code, and confirm that disc breaking is widespread and enhances accretion on to the central object. For some inclinations, the disc goes through strong Kozai cycles. Disc breaking promotes markedly enhanced and variable accretion and potentially produces high-energy particles or radiation through shocks. This would have significant implications for all binary systems: e.g. accretion outbursts in X-ray binaries and fuelling supermassive black hole (SMBH) binaries. The behaviour we have discussed in this work is relevant to a variety of astrophysical systems, for example X-ray binaries, where the disc plane may be tilted by radiation warping, SMBH binaries, where accretion of misaligned gas can create effectively random inclinations and protostellar binaries, where a disc may be misaligned by a variety of effects such as binary capture/exchange, accretion after binary formation.

  11. Revival of the Jumping Disc

    ERIC Educational Resources Information Center

    Ucke, C.; Schlichting, H-J.

    2009-01-01

    Snap discs made of bimetal have many technical applications as thermostats. Jumping discs are a toy version of such snap discs. Besides giving technical information, we describe physical investigations. We show especially how, through simple measurements and calculations, you can determine the initial speed ([approximately equal to]3.5 m…

  12. Impact of Gene Patents and Licensing Practices on Access to Genetic Testing for Inherited Susceptibility to Cancer: Comparing Breast and Ovarian Cancers to Colon Cancers

    PubMed Central

    Cook-Deegan, Robert; DeRienzo, Christopher; Carbone, Julia; Chandrasekharan, Subhashini; Heaney, Christopher; Conover, Christopher

    2011-01-01

    Genetic testing for inherited susceptibility to breast and ovarian cancer can be compared to similar testing for colorectal cancer as a “natural experiment.” Inherited susceptibility accounts for a similar fraction of both cancers and genetic testing results guide decisions about options for prophylactic surgery in both sets of conditions. One major difference is that in the United States, Myriad Genetics is the sole provider of genetic testing, because it has sole control of relevant patents for BRCA1 and BRCA2 genes whereas genetic testing for familial colorectal cancer is available from multiple laboratories. Colorectal cancer-associated genes are also patented, but they have been nonexclusively licensed. Prices for BRCA1 and 2 testing do not reflect an obvious price premium attributable to exclusive patent rights compared to colorectal cancer testing, and indeed Myriad’s per unit costs are somewhat lower for BRCA1/2 testing than testing for colorectal cancer susceptibility. Myriad has not enforced patents against basic research, and negotiated a Memorandum of Understanding with the National Cancer Institute in 1999 for institutional BRCA testing in clinical research. The main impact of patenting and licensing in BRCA compared to colorectal cancer is the business model of genetic testing, with a sole provider for BRCA and multiple laboratories for colorectal cancer genetic testing. Myriad’s sole provider model has not worked in jurisdictions outside the United States, largely because of differences in breadth of patent protection, responses of government health services, and difficulty in patent enforcement. PMID:20393305

  13. Hybrid cervical disc arthroplasty.

    PubMed

    Tu, Tsung-Hsi; Wu, Jau-Ching; Cheng, Henrich; Mummaneni, Praveen V

    2017-01-01

    For patients with multilevel cervical stenosis at nonadjacent segments, one of the traditional approaches has included a multilevel fusion of the abnormal segments as well as the intervening normal segment. In this video we demonstrate an alternative treatment plan with tailored use of a combination of anterior cervical discectomy and fusion (ACDF) and cervical disc arthroplasty (CDA) with an intervening skipped level. The authors present the case of a 72-year-old woman with myeloradiculopathy and a large disc herniation with facet joint degeneration at C3-4 and bulging disc at C5-6. After nonoperative treatment failed, she underwent a single-level ACDF at C3-4 and single-level arthroplasty at C5-6, which successfully relieved her symptoms. No intervention was performed at the normal intervening C4-5 segment. By using ACDF combined with arthroplasty, the authors have avoided a 3-level fusion for this patient and maintained the range of motion of 2 disc levels. The video can be found here: https://youtu.be/OrxcPUBvqLk .

  14. The Teddy Bears' Disc.

    ERIC Educational Resources Information Center

    Laurillard, Diana

    1985-01-01

    Reports an evaluation of the Teddy Bear disc, an interactive videodisc developed at the Open University for a second-level course in metallurgy and materials technology. Findings from observation of students utilizing the videodisc are reviewed; successful design features and design problems are considered; and development costs are outlined. (MBR)

  15. Changes in disc status in the reducing and nonreducing anterior disc displacement of temporomandibular joint: a longitudinal retrospective study.

    PubMed

    Hu, Ying Kai; Yang, Chi; Xie, Qian Yang

    2016-09-27

    Treatment procedures for anterior disc displacement (ADD) of temporomandibular joint (TMJ) are far from reaching a consensus. The aim of the study was to evaluate disc status changes of anterior disc displacement with reduction (ADDWR) and without reduction (ADDWoR) comparatively, to get a better understanding of the disease progress without intervention. This longitudinal retrospective study included 217 joints in 165 patients, which were divided into ADDWR group and ADDWoR group based on magnetic resonance imaging (MRI) examination. The joints were assessed quantitatively for disc length and displacement distance at initial and follow-up visits. Disc morphology, which was classified in 5 types, was also evaluated. Paired t-test and Wilcoxon signed rank test were used to assess intra-group differences and independent t-test for inter-group differences. Moreover, analysis of covariance was applied to analyze influential factors for changes in disc length and displacement distance. According to our results, discs tended to become shorter, move further forward and distort more seriously in ADDWoR group than in ADDWR group after follow-up. Moreover, discs were prone to become shorter and more anteriorly displaced in teenagers, type I and III morphologies, advanced Wilkes stages, or those with joint effusion. Follow-up period seemed to be not critical.

  16. Changes in disc status in the reducing and nonreducing anterior disc displacement of temporomandibular joint: a longitudinal retrospective study

    PubMed Central

    Hu, Ying Kai; Yang, Chi; Xie, Qian Yang

    2016-01-01

    Treatment procedures for anterior disc displacement (ADD) of temporomandibular joint (TMJ) are far from reaching a consensus. The aim of the study was to evaluate disc status changes of anterior disc displacement with reduction (ADDWR) and without reduction (ADDWoR) comparatively, to get a better understanding of the disease progress without intervention. This longitudinal retrospective study included 217 joints in 165 patients, which were divided into ADDWR group and ADDWoR group based on magnetic resonance imaging (MRI) examination. The joints were assessed quantitatively for disc length and displacement distance at initial and follow-up visits. Disc morphology, which was classified in 5 types, was also evaluated. Paired t-test and Wilcoxon signed rank test were used to assess intra-group differences and independent t-test for inter-group differences. Moreover, analysis of covariance was applied to analyze influential factors for changes in disc length and displacement distance. According to our results, discs tended to become shorter, move further forward and distort more seriously in ADDWoR group than in ADDWR group after follow-up. Moreover, discs were prone to become shorter and more anteriorly displaced in teenagers, type I and III morphologies, advanced Wilkes stages, or those with joint effusion. Follow-up period seemed to be not critical. PMID:27671371

  17. [Evaluation of second-line antituberculosis drug susceptibilities of multidrug-resistant Mycobacterium tuberculosis complex isolates by E-test method].

    PubMed

    Şimşek, Hülya; Tarhan, Gülnur; Cesur, Salih

    2015-01-01

    Multidrug-resistant (MDR) tuberculosis (TB) constitutes a restricting factor for the effective treatment of TB worldwide. Early diagnosis and appropriate treatment of patients are the most effective strategy in the control of MDR-TB. Therefore, knowledge of drug resistance patterns of the MDR-TB clinical isolates are necessary in planning of an appropriate treatment regimen for the patient. The aims of this study were to detect the susceptibilities of MDR-TB isolates to second-line anti-TB drugs by E-test method, and to compare their results with Löwenstein-Jensen (LJ) proportion method. A total of 122 MDR (resistant to isoniazid and rifampicin) Mycobacterium tuberculosis complex (MTC) strains isolated from samples of patients with pulmonary TB were included in the study. The isolates were identified by conventional methods and first-line anti-TB drug susceptibility testing was performed by the proportion method using LJ medium. The susceptibilities of the isolates to second-line anti-TB drugs [kanamycin (KN), ofloxacin (OFL), ethionamid (ETN), linezolid (LIN)] were tested by proportion method on LJ medium and E-test method on Middlebrook 7H11 medium. For this purpose, E-test strips (bioMerieux, Fransa) of KN (0.016-256 mg/ml), OFL (0.02-32 mg/ml), ETN (0.016-256 mg/ml), and LIN (0.016-256 mg/ml) were used. The susceptibility tests were evaluated in 5., 7., and 10. days after application of the E-test strips, and proportion method on LJ medium was evaluated 28 days later. Second line-anti-TB drug susceptibility results were obtained in 5 to 10 days by E-test. Of the MDR MTC strains 98% (119/122) were susceptible to KN, OFL and LIN, while 2% (3/122) of the strains were resistant to KN and ETN. The correlation between E-test and LJ proportion method was estimated as 96% for KN and ETN, 98% for OFL, and 100% for LIN. When compared with LJ proportion method, the specificity of E-test in the detection of susceptibility to KN, OFL, ETN and LIN were 60%, 38%, 60%, and

  18. 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

  19. Fluoroquinolone susceptibility testing of Salmonella enterica: detection of acquired resistance and selection of zone diameter breakpoints for levofloxacin and ofloxacin.

    PubMed

    Sjölund-Karlsson, Maria; Howie, Rebecca L; Crump, John A; Whichard, Jean M

    2014-03-01

    Fluoroquinolones (e.g., ciprofloxacin) have become a mainstay for treating severe Salmonella infections in adults. Fluoroquinolone resistance in Salmonella is mostly due to mutations in the topoisomerase genes, but plasmid-mediated quinolone resistance (PMQR) mechanisms have also been described. In 2012, the Clinical and Laboratory Standards Institute (CLSI) revised the ciprofloxacin interpretive criteria (breakpoints) for disk diffusion and MIC test methods for Salmonella. In 2013, the CLSI published MIC breakpoints for Salmonella to levofloxacin and ofloxacin, but breakpoints for assigning disk diffusion results to susceptible (S), intermediate (I), and resistant (R) categories are still needed. In this study, the MICs and inhibition zone diameters for nalidixic acid, ciprofloxacin, levofloxacin, and ofloxacin were determined for 100 clinical isolates of nontyphi Salmonella with or without resistance mechanisms. We confirmed that the new levofloxacin MIC breakpoints resulted in the highest category agreement (94%) when plotted against the ciprofloxacin MICs and that the new ofloxacin MIC breakpoints resulted in 92% category agreement between ofloxacin and ciprofloxacin. By applying the new MIC breakpoints in the MIC zone scattergrams for levofloxacin and ofloxacin, the following disk diffusion breakpoints generated the least number of errors: ≥28 mm (S), 19 to 27 mm (I), and ≤18 mm (R) for levofloxacin and ≥25 mm (S), 16 to 24 mm (I), and ≤15 mm (R) for ofloxacin. Neither the levofloxacin nor the ofloxacin disk yielded good separation of isolates with and without resistance mechanisms. Further studies will be needed to develop a disk diffusion assay that efficiently detects all isolates with acquired resistance to fluoroquinolones.

  20. The debris disc around HIP 17439

    NASA Astrophysics Data System (ADS)

    Schüppler, Christian; Löhne, Torsten; Krivov, Alexander

    2013-07-01

    In the framework of the Herschel Open Time Key Programme DUNES the debris disc around the K2 V star HIP 17439 was observed. In PACS images the disc emission is spatially clearly extended. A simultaneous analysis of photometric observations and radial brightness profiles from the resolved images provides valuable hints for the disc structure. In an analytical model we adopted power laws for the size and radial distribution of the circumstellar dust and tested two different scenarios: (1) a broad dust ring with a radial extent of about 200AU, (2) two independent dust rings separated by a gap of several tens of AU. Both models fit the spectral energy distribution and the radial profiles quite well. In case (1) the parameters found are consistent with dust stemming from an outer planetesimal belt at ~140AU and strong transport mechanisms that drag the particles inward. Model (2) would imply two planetesimal belts, producing a narrow inner and wider outer distribution of dust.

  1. 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.

  2. Interaction between FEZ1 and DISC1 in regulation of neuronal development and risk for schizophrenia.

    PubMed

    Kang, Eunchai; Burdick, Katherine E; Kim, Ju Young; Duan, Xin; Guo, Junjie U; Sailor, Kurt A; Jung, Dhong-Eun; Ganesan, Sundar; Choi, Sungkyung; Pradhan, Dennis; Lu, Bai; Avramopoulos, Dimitrios; Christian, Kimberly; Malhotra, Anil K; Song, Hongjun; Ming, Guo-li

    2011-11-17

    Disrupted-in Schizophrenia 1 (DISC1), a susceptibility gene for major mental disorders, encodes a scaffold protein that has a multifaceted impact on neuronal development. How DISC1 regulates different aspects of neuronal development is not well understood. Here, we show that Fasciculation and Elongation Protein Zeta-1 (FEZ1) interacts with DISC1 to synergistically regulate dendritic growth of newborn neurons in the adult mouse hippocampus, and that this pathway complements a parallel DISC1-NDEL1 interaction that regulates cell positioning and morphogenesis of newborn neurons. Furthermore, genetic association analysis of two independent cohorts of schizophrenia patients and healthy controls reveals an epistatic interaction between FEZ1 and DISC1, but not between FEZ1 and NDEL1, for risk of schizophrenia. Our findings support a model in which DISC1 regulates distinct aspects of neuronal development through its interaction with different intracellular partners and such epistasis may contribute to increased risk for schizophrenia.

  3. 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.

  4. Testing the 'hybrid susceptibility' and 'phenological sink' hypotheses using the P. balsamifera - P. deltoides hybrid zone and septoria leaf spot [Septoria musiva].

    PubMed

    LeBoldus, Jared M; Isabel, Nathalie; Floate, Kevin D; Blenis, Peter; Thomas, Barb R

    2013-01-01

    Hybrid genotypes that arise between plant species frequently have increased susceptibility to arthropod pests and fungal pathogens. This pattern has been attributed to the breakdown of plant defenses ('Hybrid susceptibility' hypothesis) and (or) to extended periods of susceptibility attributed to plant phenologies in zones of species overlap and (or) hybridization ('phenological sink' hypothesis). We examined these hypotheses by assessing the susceptibility of parental and hybrid Populus host genotypes to a leaf spot disease caused by the fungal pathogen Septoria musiva. For this purpose, 214 genotypes were obtained from morphologically pure zones of P. balsamifera and P. deltoides, and from an intervening zone of overlap and hybridization on the drainage of the Red Deer River, Alberta, Canada. Genotypes were identified as P. balsamifera, P. deltoides, or hybrid using a suite of 27 species-specific SNP markers. Initially the genetic structure of the hybrid zone was characterized with 27.7% of trees classified as admixed individuals. To test the hybrid susceptibility hypothesis, a subset of 52 genotypes was inoculated with four isolates of S. musiva. Levels of susceptibility were P. balsamifera > F1 hybrid > P. deltoides. A further 53 genotypes were grown in a common garden to assess the effect of genotype on variation in leaf phenology. Leaf phenology was more variable within the category of hybrid genotypes than within categories of either parental species. Leaf phenology was also more variable for the category of trees originating in the hybrid (P. balsamifera - P. deltoides [hybrid and parental genotypes combined]) zone than in adjacent pure zones of the parental species. The results from the inoculation experiment support the hybrid intermediacy hypothesis. The results from the common garden experiment support the 'phenological sink' hypothesis. These findings have greatly increased our understanding of the epidemiology and ecology of fungal pathogens in plant

  5. Disk diffusion susceptibility testing of two macrolide antimicrobial agents: revised interpretive criteria for erythromycin and preliminary guidelines for roxithromycin (RU 965).

    PubMed Central

    Jones, R N; Barry, A L; Fuchs, P C; Thornsberry, C

    1986-01-01

    The 15-micrograms erythromycin disk was twice evaluated for interpretive accuracy against 417 and then 266 strains of gram-positive cocci, Neisseria meningitidis, and Haemophilus influenzae by using the criteria suggested by the National Committee for Clinical Laboratory Standards. These studies suggest a revision of streptococcal and Staphylococcus sp. interpretive guidelines to criteria (greater than or equal to 23 mm = susceptible, less than or equal to 13 mm = resistant) that are more compatible with in vivo erythromycin concentrations. It is also recommended that zone diameters be modified for H. influenzae (greater than or equal to 23 mm = susceptible, less than 22 mm = resistant) and that meningococci not be tested. A wide moderately susceptible category (1.0 to 4.0 micrograms/ml) would primarily include enterococcus strains and those organisms that would then respond only to parenteral administration of erythromycin. Roxithromycin (RU 965 or RU 28965), a new oxime ether erythromycin derivative, was also evaluated by investigator-prepared 15-micrograms disks and later with 30- and 60-micrograms commercial disks. Although roxithromycin was comparable to erythromycin in activity and regression line statistics, changes in the susceptible disk criteria were necessary because of superior roxithromycin serum concentrations and a longer serum half-life. Preliminary susceptible breakpoint criteria were greater than 21 mm = susceptible, 10 to 20 mm = indeterminate, and less than or equal to 9 mm = resistant. By using the recommended interpretive criteria for both macrolides, less than 98% absolute agreement was obtained, therefore suggesting the application of a spectrum class concept. PMID:3091634

  6. Carbapenem susceptibility testing errors using three automated systems, disk diffusion, Etest, and broth microdilution and carbapenem resistance genes in isolates of Acinetobacter baumannii-calcoaceticus complex.

    PubMed

    Markelz, Ana Elizabeth; Mende, Katrin; Murray, Clinton K; Yu, Xin; Zera, Wendy C; Hospenthal, Duane R; Beckius, Miriam L; Calvano, Tatjana; Akers, Kevin S

    2011-10-01

    The Acinetobacter baumannii-calcoaceticus complex (ABC) is associated with increasing carbapenem resistance, necessitating accurate resistance testing to maximize therapeutic options. We determined the accuracy of carbapenem antimicrobial susceptibility tests for ABC isolates and surveyed them for genetic determinants of carbapenem resistance. A total of 107 single-patient ABC isolates from blood and wound infections from 2006 to 2008 were evaluated. MICs of imipenem, meropenem, and doripenem determined by broth microdilution (BMD) were compared to results obtained by disk diffusion, Etest, and automated methods (the MicroScan, Phoenix, and Vitek 2 systems). Discordant results were categorized as very major errors (VME), major errors (ME), and minor errors (mE). DNA sequences encoding OXA beta-lactamase enzymes (bla(OXA-23-like), bla(OXA-24-like), bla(OXA-58-like), and bla(OXA-51-like)) and metallo-β-lactamases (MBLs) (IMP, VIM, and SIM1) were identified by PCR, as was the KPC2 carbapenemase gene. Imipenem was more active than meropenem and doripenem. The percentage of susceptibility was 37.4% for imipenem, 35.5% for meropenem, and 3.7% for doripenem. Manual methods were more accurate than automated methods. bla(OXA-23-like) and bla(OXA-24-like) were the primary resistance genes found. bla(OXA-58-like), MBLs, and KPC2 were not present. Both automated testing and manual testing for susceptibility to doripenem were very inaccurate, with VME rates ranging between 2.8 and 30.8%. International variability in carbapenem breakpoints and the absence of CLSI breakpoints for doripenem present a challenge in susceptibility testing.

  7. Nuclear DISC1 regulates CRE-mediated gene transcription and sleep homeostasis in the fruit fly

    PubMed Central

    Sawamura, Naoya; Ando, Tetsuya; Maruyama, Yasushi; Fujimuro, Masahiro; Mochizuki, Hiroaki; Honjo, Ken; Shimoda, Masami; Toda, Hirofumi; Sawamura-Yamamoto, Takako; Makuch, Lauren A; Hayashi, Akiko; Ishizuka, Koko; Cascella, Nicola G.; Kamiya, Atsushi; Ishida, Norio; Tomoda, Toshifumi; Hai, Tsonwin; Furukubo-Tokunaga, Katsuo; Sawa, Akira

    2009-01-01

    Disrupted-In-Schizophrenia-1 (DISC1) is one of major susceptibility factors for a wide range of mental illnesses, including schizophrenia, bipolar disorder, major depression, and autism spectrum conditions. DISC1 is located in several subcellular domains, such as the centrosome and the nucleus, and interacts with various proteins, including NudE-like (NUDEL/NDEL1) and activating transcription factor 4 (ATF4)/CREB2. Nevertheless, a role for DISC1 in vivo remains to be elucidated. Therefore, we have generated a Drosophila model for examining normal functions of DISC1 in living organisms. DISC1 transgenic flies with preferential accumulation of exogenous human DISC1 in the nucleus display disturbance in sleep homeostasis, which has been reportedly associated with CREB signaling/CRE-mediated gene transcription. Thus, in mammalian cells, we characterized nuclear DISC1, and identified a subset of nuclear DISC1 that co-localizes with the promyelocytic leukemia (PML) bodies, a nuclear compartment for gene transcription. Furthermore, we identified three functional cis-elements that regulate the nuclear localization of DISC1. We also report that DISC1 interacts with ATF4/CREB2 and a co-repressor N-CoR, modulating CRE-mediated gene transcription. PMID:18762802

  8. Nuclear DISC1 regulates CRE-mediated gene transcription and sleep homeostasis in the fruit fly.

    PubMed

    Sawamura, N; Ando, T; Maruyama, Y; Fujimuro, M; Mochizuki, H; Honjo, K; Shimoda, M; Toda, H; Sawamura-Yamamoto, T; Makuch, L A; Hayashi, A; Ishizuka, K; Cascella, N G; Kamiya, A; Ishida, N; Tomoda, T; Hai, T; Furukubo-Tokunaga, K; Sawa, A

    2008-12-01

    Disrupted-in-schizophrenia-1 (DISC1) is one of major susceptibility factors for a wide range of mental illnesses, including schizophrenia, bipolar disorder, major depression and autism spectrum conditions. DISC1 is located in several subcellular domains, such as the centrosome and the nucleus, and interacts with various proteins, including NudE-like (NUDEL/NDEL1) and activating transcription factor 4 (ATF4)/CREB2. Nevertheless, a role for DISC1 in vivo remains to be elucidated. Therefore, we have generated a Drosophila model for examining normal functions of DISC1 in living organisms. DISC1 transgenic flies with preferential accumulation of exogenous human DISC1 in the nucleus display disturbance in sleep homeostasis, which has been reportedly associated with CREB signaling/CRE-mediated gene transcription. Thus, in mammalian cells, we characterized nuclear DISC1, and identified a subset of nuclear DISC1 that colocalizes with the promyelocytic leukemia (PML) bodies, a nuclear compartment for gene transcription. Furthermore, we identified three functional cis-elements that regulate the nuclear localization of DISC1. We also report that DISC1 interacts with ATF4/CREB2 and a corepressor N-CoR, modulating CRE-mediated gene transcription.

  9. Intervertebral disc replacement. Experimental study.

    PubMed

    Kostuik, J P

    1997-04-01

    Arthrodesis of the lumbosacral spine, although satisfactory for a majority of patients, has long term sequelae in 30% of patients. This is particularly true for adjacent segment degeneration. Numerous attempts at providing a mobile motion segment have been made in the past. The current status of the development of dynamic intervertebral prosthesis, including biomechanical and clinical data have been presented. The relevant material properties of plastics, ceramics, and metal are presented with the conclusion that metals currently present with the greatest longevity without undue fatigue and wear as many as 100,000,000 cycles (40 years use) as an alternative to spinal fusion. An analysis of the kinematics of the motion segment have resulted, together with the material properties in the development of a dynamic intervertebral disc for use in the lumbar spine. The disc resembles a normal motion segment. In motion stiffness and center of rotation, wear debris development in 1/300 equivalent to that of a total hip prosthesis for the same given time. Safety features include immediate screw fixation to prevent displacement, a wedge elastic (spring) shape, and a bony porous ingrowth surface. The prosthesis is constructed of cobalt chromium and titanium with minimal corrosive properties on long term testing.

  10. Efficacy of Ciprofloxacin for Treatment of Cholera Associated with Diminished Susceptibility to Ciprofloxacin to Vibrio cholerae O1

    PubMed Central

    Khan, Wasif Ali; Saha, Debasish; Ahmed, Sabeena; Salam, Mohammed Abdus; Bennish, Michael Louis

    2015-01-01

    Objective We identified a poor clinical response to treatment of cholera with a single 1 g dose of ciprofloxacin, a standard treatment for cholera. Methods To determine reasons for the poor response and better therapeutic approaches we examined the minimal inhibitor concentration (MIC, n = 275) and disc-diffusion zone sizes (n = 205) for ciprofloxacin and nalidixic acid of V. cholerae O1 strains isolated in Bangladesh from 1994 to 2012, and reexamined data from 161patients infected with Vibrio cholerae O1 recruited in four clinical trials who received single- or multiple-dose ciprofloxacin for treatment of cholera and compared their clinical response to the V. cholerae O1 susceptibility. Results Although all 275 isolates of V. cholerae O1 remained susceptible to ciprofloxacin using standard MIC and disc-diffusion thresholds, the MIC90 to ciprofloxacin increased from 0.010 in 1994 to 0.475 μgm/ml in 2012. Isolates became frankly resistant to nalidixic with the MIC90 increasing from 21 μgm/ml in 1994 to >256 μgm/ml and 166 of 205 isolates from 1994 to 2005 being frankly resistant using disc-diffusion testing. Isolates resistant to nalidixic acid by disc-diffusion testing had a median ciprofloxacin MIC of 0.190 μgm/ml (10th-90th centiles 0.022 to 0.380); nalidixic acid-susceptible isolates had a median ciprofloxacin MIC of 0.002 (0.002 to 0.012).The rate of clinical success with single-dose ciprofloxacin treatment for nalidixic acid-susceptible strains was 94% (61 of 65 patients) and bacteriologic success 97% (63/65) compared to 18% (12/67) and 8% (5/67) respectively with nalidixic acid-resistant strains (P<0.001 for both comparisons). Multiple-dose treatment with ciprofloxacin had 86% and 100% clinical and bacteriologic success rates respectively in patients infected with nalidixic acid-susceptible strains of V. cholerae O1 compared to clinical success 67% and bacteriologic success 60% with nalidixic acid-resistant strains. Conclusions Single-dose ciprofloxacin

  11. Effects of Maternal Sensitivity on Low Birth Weight Children's Academic Achievement: A Test of Differential Susceptibility versus Diathesis Stress

    ERIC Educational Resources Information Center

    Jaekel, Julia; Pluess, Michael; Belsky, Jay; Wolke, Dieter

    2015-01-01

    Background: Differential Susceptibility Theory (DST) postulates that some children are more affected--for better and for worse--by developmental experiences, including parenting, than others. Low birth weight (LBW, 1,500-2,499 g) may not only be a predictor for neurodevelopmental impairment but also a marker for prenatally programmed…

  12. A multi-annual landslide inventory for the assessment of shallow landslide susceptibility - Two test cases in Vorarlberg, Austria

    NASA Astrophysics Data System (ADS)

    Zieher, Thomas; Perzl, Frank; Rössel, Monika; Rutzinger, Martin; Meißl, Gertraud; Markart, Gerhard; Geitner, Clemens

    2016-04-01

    Geomorphological landslide inventories provide crucial input data for any study on the assessment of landslide susceptibility, hazard or risk. Several approaches for assessing landslide susceptibility have been proposed to identify areas particularly vulnerable to this natural hazard. What they have in common is the need for data of observed landslides. Therefore the first step of any study on landslide susceptibility is usually the compilation of a geomorphological landslide inventory using a geographical information system. Recent research has proved the feasibility of orthophoto interpretation for the preparation of an inventory aimed at the delineation of landslides with the use of distinctive signs in the imagery data. In this study a multi-annual landslide inventory focusing on shallow landslides (i.e. translational soil slides of 0-2 m in depth) was compiled for two study areas in Vorarlberg (Austria) from the interpretation of nine orthophoto series. In addition, derivatives of two generations of airborne laser scanning data aided the mapping procedure. Landslide scar areas were delineated on the basis of a high-resolution differential digital terrain model. The derivation of landslide volumes, depths and depth-to-length ratios are discussed. Results show that most mapped landslides meet the definition of a shallow landslide. The inventory therefore provides the data basis for the assessment of shallow landslide susceptibility and allows for the application of various modelling techniques.

  13. Utility of antimicrobial susceptibility testing of multiple Haemophilus influenzae isolates from throat swabs of children with adenoid hypertrophy.

    PubMed

    Antos-Bielska, Małgorzata; Lau-Dworak, Magdalena; Olszewska-Sosińska, Olga; Zielnik-Jurkiewicz, Beata; Trafny, Elżbieta A

    2014-07-01

    Eleven out of 40 children with adenoiditis were colonized with multiple genotypes of Haemophilus influenzae. Heterogeneous antibiotic susceptibility to ampicillin and cotrimoxazole was observed in 6 children. A multiple-colony methodology may potentially help to find the resistant strains of H. influenzae in patients who do not respond to the antibiotic treatment.

  14. The influence of land use change on landslide susceptibility zonation: the Briga catchment test site (Messina, Italy).

    PubMed

    Reichenbach, P; Busca, C; Mondini, A C; Rossi, M

    2014-12-01

    The spatial distribution of landslides is influenced by different climatic conditions and environmental settings including topography, morphology, hydrology, lithology, and land use. In this work, we have attempted to evaluate the influence of land use change on landslide susceptibility (LS) for a small study area located in the southern part of the Briga catchment, along the Ionian coast of Sicily (Italy). On October 1, 2009, the area was hit by an intense rainfall event that triggered abundant slope failures and resulted in widespread erosion. After the storm, an inventory map showing the distribution of pre-event and event landslides was prepared for the area. Moreover, two different land use maps were developed: the first was obtained through a semi-automatic classification of digitized aerial photographs acquired in 1954, the second through the combination of supervised classifications of two recent QuickBird images. Exploiting the two land use maps and different land use scenarios, LS zonations were prepared through multivariate statistical analyses. Differences in the susceptibility models were analyzed and quantified to evaluate the effects of land use change on the susceptibility zonation. Susceptibility maps show an increase in the areal percentage and number of slope units classified as unstable related to the increase in bare soils to the detriment of forested areas.

  15. LUMBAR DISC HERNIATION

    PubMed Central

    Vialle, Luis Roberto; Vialle, Emiliano Neves; Suárez Henao, Juan Esteban; Giraldo, Gustavo

    2015-01-01

    Lumbar disc herniation is the most common diagnosis among the degenerative abnormalities of the lumbar spine (affecting 2 to 3% of the population), and is the principal cause of spinal surgery among the adult population. The typical clinical picture includes initial lumbalgia, followed by progressive sciatica. The natural history of disc herniation is one of rapid resolution of the symptoms (four to six weeks). The initial treatment should be conservative, managed through medication and physiotherapy, sometimes associated with percutaneous nerve root block. Surgical treatment is indicated if pain control is unsuccessful, if there is a motor deficit greater than grade 3, if there is radicular pain associated with foraminal stenosis, or if cauda equina syndrome is present. The latter represents a medical emergency. A refined surgical technique, with removal of the extruded fragment and preservation of the ligamentum flavum, resolves the sciatic symptoms and reduces the risk of recurrence over the long term. PMID:27019834

  16. Biomechanics of Disc Degeneration

    PubMed Central

    Palepu, V.; Kodigudla, M.; Goel, V. K.

    2012-01-01

    Disc degeneration and associated disorders are among the most debated topics in the orthopedic literature over the past few decades. These may be attributed to interrelated mechanical, biochemical, and environmental factors. The treatment options vary from conservative approaches to surgery, depending on the severity of degeneration and response to conservative therapies. Spinal fusion is considered to be the “gold standard” in surgical methods till date. However, the association of adjacent level degeneration has led to the evolution of motion preservation technologies like spinal arthroplasty and posterior dynamic stabilization systems. These new technologies are aimed to address pain and preserve motion while maintaining a proper load sharing among various spinal elements. This paper provides an elaborative biomechanical review of the technologies aimed to address the disc degeneration and reiterates the point that biomechanical efficacy followed by long-term clinical success will allow these nonfusion technologies as alternatives to fusion, at least in certain patient population. PMID:22745914

  17. Mechanotransduction in intervertebral discs

    PubMed Central

    Tsai, Tsung-Ting; Cheng, Chao-Min; Chen, Chien-Fu; Lai, Po-Liang

    2014-01-01

    Mechanotransduction plays a critical role in intracellular functioning—it allows cells to translate external physical forces into internal biochemical activities, thereby affecting processes ranging from proliferation and apoptosis to gene expression and protein synthesis in a complex web of interactions and reactions. Accordingly, aberrant mechanotransduction can either lead to, or be a result of, a variety of diseases or degenerative states. In this review, we provide an overview of mechanotransduction in the context of intervertebral discs, with a focus on the latest methods of investigating mechanotransduction and the most recent findings regarding the means and effects of mechanotransduction in healthy and degenerative discs. We also provide some discussion of potential directions for future research and treatments. PMID:25267492

  18. In vitro susceptibility of bovine mastitis pathogens to a combination of penicillin and framycetin: development of interpretive criteria for testing by broth microdilution and disk diffusion.

    PubMed

    Pillar, C M; Stoneburner, A; Shinabarger, D L; Abbeloos, E; Goby, L; Bradley, Andrew J

    2014-10-01

    Dry cow therapy is an important part of mastitis control. This therapy typically consists of an antibiotic or antibiotics administered at a single dose by intramammary infusion at dry off to treat or prevent infection by prevalent mastitis pathogens. A combination dry cow therapy consisting of the active components penicillin and framycetin is currently used in several countries. Despite its use, standardized methods for the susceptibility testing of this combination against mastitis pathogens have not been established. In this study, which used Clinical and Laboratory Standards Institute methodology, preliminary interpretive criteria for the broth microdilution minimum inhibitory concentration (MIC) testing of mastitis pathogens to penicillin combined with framycetin (2:1 wt/wt) were established based on the amount of drug achieved and maintained postadministration in the udder. Based on resulting MIC distributions of recent veterinary field isolates and a subset of isolates preselected for resistance to β-lactams or aminoglycosides and concentrations achieved postadministration, criteria for broth microdilution testing of the combination (susceptible, intermediate, resistant in micrograms per milliliter) were set as follows: Escherichia coli ≤8/4, 16/8, ≥32/16; Staphylococcus spp. ≤2/1, 4/2-8/4, >16/8; Streptococcus uberis and Streptococcus dysgalactiae <0.25/0.12, 0.5/0.25-2/1, >4/2. A disk diffusion test using disks containing 100 μg of framycetin and 10 IU of penicillin was also developed, and preliminary interpretive criteria (susceptible, intermediate, resistant in millimeters) were set based on correlation to broth MIC values and the minimization of interpretive errors between isolates tested concurrently by broth microdilution and disk diffusion as follows: E. coli ≥18, 16-17, ≤15; Staphylococcus spp. ≥21, 18-20, ≤17; Strep. uberis and Strep. dysgalactiae ≥21, 19-20, ≤18. In addition, ranges for the quality control of the testing of

  19. Susceptibility Testing of Antibiotics That Degrade Faster than the Doubling Time of Slow-Growing Mycobacteria: Ertapenem Sterilizing Effect versus Mycobacterium tuberculosis

    PubMed Central

    Srivastava, Shashikant; van Rijn, Sander P.; Wessels, A. Mireille A.; Gumbo, Tawanda

    2016-01-01

    Drug susceptibility tests (DSTs) for Mycobacterium tuberculosis require at least 7 days of incubation. Drugs that are unstable at 37°C, such as ertapenem, are likely to be degraded before killing or inhibiting slow-growing bacteria. This would alter the MICs of these drugs, including ertapenem, leading to falsely high MICs. Here, we describe a new strategy we developed to perform DSTs and measure MICs for such unstable compounds. PMID:26926650

  20. In Vitro Activity of Fosfomycin against a Collection of Clinical Pseudomonas aeruginosa Isolates from 16 Spanish Hospitals: Establishing the Validity of Standard Broth Microdilution as Susceptibility Testing Method

    PubMed Central

    Díez-Aguilar, María; del Campo, Rosa; García-Castillo, María; Zamora, Javier; Cantón, Rafael

    2013-01-01

    The broth microdilution method for fosfomycin and Pseudomonas aeruginosa was assessed and compared with the approved agar dilution method in 206 genetically unrelated P. aeruginosa clinical isolates. Essential agreement between the two methods was 84%, and categorical agreement was 89.3%. Additionally, Etest and disk diffusion assays were performed. Results validate broth microdilution as a reliable susceptibility testing method for fosfomycin against P. aeruginosa. Conversely, unacceptable concordance was established between Etest and disk diffusion results with agar dilution results. PMID:23939889

  1. Influence of clinical breakpoint changes from CLSI 2009 to EUCAST 2011 antimicrobial susceptibility testing guidelines on multidrug resistance rates of Gram-negative rods.

    PubMed

    Hombach, Michael; Wolfensberger, Aline; Kuster, Stefan P; Böttger, Erik C

    2013-07-01

    Multidrug resistance (MDR) rates of Gram-negative rods were analyzed comparing CLSI 2009 and EUCAST 2011 antibiotic susceptibility testing guidelines. After EUCAST 2011 was applied, the MDR rates increased for Klebsiella pneumoniae (2.2%), Enterobacter cloacae (1.1%), Pseudomonas aeruginosa (0.7%), and Escherichia coli (0.4%). A total of 24% of Enterobacteriaceae MDR isolates and 12% of P. aeruginosa MDR isolates were categorized as MDR due to breakpoint changes.

  2. Total disc replacement.

    PubMed

    Vital, J-M; Boissière, L

    2014-02-01

    Total disc replacement (TDR) (partial disc replacement will not be described) has been used in the lumbar spine since the 1980s, and more recently in the cervical spine. Although the biomechanical concepts are the same and both are inserted through an anterior approach, lumbar TDR is conventionally indicated for chronic low back pain, whereas cervical TDR is used for soft discal hernia resulting in cervicobrachial neuralgia. The insertion technique must be rigorous, with precise centering in the disc space, taking account of vascular anatomy, which is more complex in the lumbar region, particularly proximally to L5-S1. All of the numerous studies, including prospective randomized comparative trials, have demonstrated non-inferiority to fusion, or even short-term superiority regarding speed of improvement. The main implant-related complication is bridging heterotopic ossification with resulting loss of range of motion and increased rates of adjacent segment degeneration, although with an incidence lower than after arthrodesis. A sufficiently long follow-up, which has not yet been reached, will be necessary to establish definitively an advantage for TDR, particularly in the cervical spine.

  3. The DISC1 promoter: characterization and regulation by FOXP2.

    PubMed

    Walker, Rosie M; Hill, Alison E; Newman, Alice C; Hamilton, Gillian; Torrance, Helen S; Anderson, Susan M; Ogawa, Fumiaki; Derizioti, Pelagia; Nicod, Jérôme; Vernes, Sonja C; Fisher, Simon E; Thomson, Pippa A; Porteous, David J; Evans, Kathryn L

    2012-07-01

    Disrupted in schizophrenia 1 (DISC1) is a leading candidate susceptibility gene for schizophrenia, bipolar disorder and recurrent major depression, which has been implicated in other psychiatric illnesses of neurodevelopmental origin, including autism. DISC1 was initially identified at the breakpoint of a balanced chromosomal translocation, t(1;11) (q42.1;14.3), in a family with a high incidence of psychiatric illness. Carriers of the translocation show a 50% reduction in DISC1 protein levels, suggesting altered DISC1 expression as a pathogenic mechanism in psychiatric illness. Altered DISC1 expression in the post-mortem brains of individuals with psychiatric illness and the frequent implication of non-coding regions of the gene by association analysis further support this assertion. Here, we provide the first characterization of the DISC1 promoter region. Using dual luciferase assays, we demonstrate that a region -300 to -177 bp relative to the transcription start site (TSS) contributes positively to DISC1 promoter activity, while a region -982 to -301 bp relative to the TSS confers a repressive effect. We further demonstrate inhibition of DISC1 promoter activity and protein expression by forkhead-box P2 (FOXP2), a transcription factor implicated in speech and language function. This inhibition is diminished by two distinct FOXP2 point mutations, R553H and R328X, which were previously found in families affected by developmental verbal dyspraxia. Our work identifies an intriguing mechanistic link between neurodevelopmental disorders that have traditionally been viewed as diagnostically distinct but which do share varying degrees of phenotypic overlap.

  4. Mechanics of Actuated Disc Cutting

    NASA Astrophysics Data System (ADS)

    Dehkhoda, Sevda; Detournay, Emmanuel

    2017-02-01

    This paper investigates the mechanics of an actuated disc cutter with the objective of determining the average forces acting on the disc as a function of the parameters characterizing its motion. The specific problem considered is that of a disc cutter revolving off-centrically at constant angular velocity around a secondary axis rigidly attached to a cartridge, which is moving at constant velocity and undercutting rock at a constant depth. This model represents an idealization of a technology that has been implemented in a number of hard rock mechanical excavators with the goal of reducing the average thrust force to be provided by the excavation equipment. By assuming perfect conformance of the rock with the actuated disc as well as a prescribed motion of the disc (perfectly rigid machine), the evolution of the contact surface between the disc and the rock during one actuation of the disc can be computed. Coupled with simple cutter/rock interaction models that embody either a ductile or a brittle mode of fragmentation, these kinematical considerations lead to an estimate of the average force on the cartridge and of the partitioning of the energy imparted by the disc to the rock between the actuation mechanism of the disc and the translation of the cartridge on which the actuated disc is attached.

  5. Polarimetric microlensing of circumstellar discs

    NASA Astrophysics Data System (ADS)

    Sajadian, Sedighe; Rahvar, Sohrab

    2015-12-01

    We study the benefits of polarimetry observations of microlensing events to detect and characterize circumstellar discs around the microlensed stars located at the Galactic bulge. These discs which are unresolvable from their host stars make a net polarization effect due to their projected elliptical shapes. Gravitational microlensing can magnify these signals and make them be resolved. The main aim of this work is to determine what extra information about these discs can be extracted from polarimetry observations of microlensing events in addition to those given by photometry ones. Hot discs which are closer to their host stars are more likely to be detected by microlensing, owing to more contributions in the total flux. By considering this kind of discs, we show that although the polarimetric efficiency for detecting discs is similar to the photometric observation, but polarimetry observations can help to constraint the disc geometrical parameters e.g. the disc inner radius and the lens trajectory with respect to the disc semimajor axis. On the other hand, the time-scale of polarimetric curves of these microlensing events generally increases while their photometric time-scale does not change. By performing a Monte Carlo simulation, we show that almost four optically thin discs around the Galactic bulge sources are detected (or even characterized) through photometry (or polarimetry) observations of high-magnification microlensing events during 10-yr monitoring of 150 million objects.

  6. Comparison of the Vitek 2 yeast susceptibility system with CLSI microdilution for antifungal susceptibility testing of fluconazole and voriconazole against Candida spp., using new clinical breakpoints and epidemiological cutoff values.

    PubMed

    Pfaller, Michael A; Diekema, Daniel J; Procop, Gary W; Rinaldi, Michael G

    2013-09-01

    A commercially available, fully automated yeast susceptibility test system (Vitek 2; bioMérieux, Marcy d'Etoile, France) was compared in 3 different laboratories with the Clinical and Laboratory Standards Institute (CLSI) reference microdilution (BMD) method by testing 2 quality control strains, 10 reproducibility strains, and 425 isolates of Candida spp. against fluconazole and voriconazole. Reference CLSI BMD MIC endpoints and Vitek 2 MIC endpoints were read after 24 hours and 9.1-27.1 hours incubation, respectively. Excellent essential agreement (within 2 dilutions) between the reference and Vitek 2 MICs was observed for fluconazole (97.9%) and voriconazole (96.7%). Categorical agreement (CA) between the 2 methods was assessed using the new species-specific clinical breakpoints (CBPs): susceptible (S) ≤2 μg/mL, susceptible dose-dependent (SDD) 4 μg/mL, and resistant (R) ≥8 μg/mL for fluconazole and Candida albicans, Candida tropicalis, and Candida parapsilosis and ≤32 μg/mL (SDD), ≥64 μg/mL (R) for Candida glabrata; S ≤0.12 μg/mL, SDD 0.25-0.5 μg/mL, R ≥1 μg/mL for voriconazole and C. albicans, C. tropicalis, and C. parapsilosis, and ≤0.5 μg/mL (S), 1 μg/mL (SDD), ≥2 μg/mL (R) for Candida krusei. The epidemiological cutoff value (ECV) of 0.5 μg/mL for voriconazole and C. glabrata was used to differentiate wild-type (WT; MIC ≤ ECV) from non-WT (MIC > ECV) strains of this species. Due to the lack of CBPs for the less common species, the ECVs for fluconazole and voriconazole, respectively, were used for Candida lusitaniae (2 μg/mL and 0.03 μg/mL), Candida dubliniensis (0.5 μg/mL and 0.03 μg/mL), Candida guilliermondii (8 μg/mL and 0.25 μg/mL), and Candida pelliculosa (4 μg/mL and 0.25 μg/mL) to categorize isolates of these species as WT and non-WT. CA between the 2 methods was 96.8% for fluconazole and 96.5% for voriconazole with less than 1% very major errors and 1.3-3.0% major errors. The Vitek 2 yeast susceptibility system

  7. Rethinking Black Hole Accretion Discs

    NASA Astrophysics Data System (ADS)

    Salvesen, Greg

    Accretion discs are staples of astrophysics. Tapping into the gravitational potential energy of the accreting material, these discs are highly efficient machines that produce copious radiation and extreme outflows. While interesting in their own right, accretion discs also act as tools to study black holes and directly influence the properties of the Universe. Black hole X-ray binaries are fantastic natural laboratories for studying accretion disc physics and black hole phenomena. Among many of the curious behaviors exhibited by these systems are black hole state transitions -- complicated cycles of dramatic brightening and dimming. Using X-ray observations with high temporal cadence, we show that the evolution of the accretion disc spectrum during black hole state transitions can be described by a variable disc atmospheric structure without invoking a radially truncated disc geometry. The accretion disc spectrum can be a powerful diagnostic for measuring black hole spin if the effects of the disc atmosphere on the emergent spectrum are well-understood; however, properties of the disc atmosphere are largely unconstrained. Using statistical methods, we decompose this black hole spin measurement technique and show that modest uncertainties regarding the disc atmosphere can lead to erroneous spin measurements. The vertical structure of the disc is difficult to constrain due to our ignorance of the contribution to hydrostatic balance by magnetic fields, which are fundamental to the accretion process. Observations of black hole X-ray binaries and the accretion environments near supermassive black holes provide mounting evidence for strong magnetization. Performing numerical simulations of accretion discs in the shearing box approximation, we impose a net vertical magnetic flux that allows us to effectively control the level of disc magnetization. We study how dynamo activity and the properties of turbulence driven by the magnetorotational instability depend on the

  8. Susceptibility testing of Candida albicans isolated from oropharyngeal mucosa of HIV+ patients to fluconazole, amphotericin B and Caspofungin. killing kinetics of caspofungin and amphotericin B against fluconazole resistant and susceptible isolates

    PubMed Central

    de Aquino Lemos, Janine; Costa, Carolina Rodrigues; de Araújo, Crystiane Rodrigues; Souza, Lúcia Kioko Hasimoto e; Silva, Maria do Rosário Rodrigues

    2009-01-01

    A clear understanding of the pharmacodynamic properties of antifungal agents is important for the adequate treatment of fungal infections like candidiasis. For certain antifungal agents, the determination of Minimal Fungicidal Concentration (MFC) and time kill curve could be clinically more relevant than the determination of the Minimal Inhibitory Concentration (MIC). In this study, MIC and MFC to fluconazole, amphotericin B and caspofungin against C. albicans isolates and the killing patterns obtained with caspofungin and amphotericin B against susceptible and resistant strains to fluconazole were determined. The results of MICs showed that all C. albicans isolates were highly susceptible to amphotericin B, but two isolates were fluconazole resistant. The comparative analysis between MIC and MFC showed that MFC of fluconazole was fourfold higher than MIC in 41.9% of the C. albicans isolates. Same values of MFC and MIC of amphotericin B and caspofungin were found for 71% of the isolates. Correlation between time kill curves and MFC of amphotericin B and caspofungin against all 4 isolates tested was observed. The caspofungin killing effect was more evident at MFC in 6 hours of incubation than at MIC in this time, suggesting dependence of concentration. The similarity of results of time-kill curve and MFC values indicate that determination of MFC is an alternative for the detection of the fungicidal activity of these drugs. PMID:24031337

  9. Heat distribution in disc brake

    NASA Astrophysics Data System (ADS)

    Klimenda, Frantisek; Soukup, Josef; Kampo, Jan

    2016-06-01

    This article is deals by the thermal analysis of the disc brake with floating caliper. The issue is solved by numerically. The half 2D model is used for solution in program ADINA 8.8. Two brake discs without the ventilation are solved. One disc is made from cast iron and the second is made from stainless steel. Both materials are an isotropic. By acting the pressure force on the brake pads will be pressing the pads to the brake disc. Speed will be reduced (slowing down). On the contact surface generates the heat, which the disc and pads heats. In the next part of article is comparison the maximum temperature at the time of braking. The temperatures of both materials for brake disc (gray cast iron, stainless steel) are compares. The heat flux during braking for the both materials is shown.

  10. Enclosed rotary disc air pulser

    DOEpatents

    Olson, A. L.; Batcheller, Tom A.; Rindfleisch, J. A.; Morgan, John M.

    1989-01-01

    An enclosed rotary disc air pulser for use with a solvent extraction pulse olumn includes a housing having inlet, exhaust and pulse leg ports, a shaft mounted in the housing and adapted for axial rotation therein, first and second disc members secured to the shaft within the housing in spaced relation to each other to define a chamber therebetween, the chamber being in communication with the pulse leg port, the first disc member located adjacent the inlet port, the second disc member being located adjacent the exhaust port, each disc member having a milled out portion, the disc members positioned on the shaft so that as the shaft rotates, the milled out portions permit alternative cyclical communication between the inlet port and the chamber and the exhaust port and the chamber.

  11. Use of fluconazole as a surrogate marker to predict susceptibility and resistance to voriconazole among 13,338 clinical isolates of Candida spp. Tested by clinical and laboratory standards institute-recommended broth microdilution methods.

    PubMed

    Pfaller, M A; Messer, S A; Boyken, L; Rice, C; Tendolkar, S; Hollis, R J; Diekema, D J

    2007-01-01

    Clinical laboratories frequently face the problem of delayed availability of commercially prepared approved reagents for performing susceptibility testing of new antimicrobials. Although this problem is encountered more often with antibacterial agents, it is also an issue with antifungal agents. A current example is voriconazole, a new triazole antifungal with an expanded spectrum and potency against Candida spp., Aspergillus spp., and other opportunistic fungal pathogens. The present study addresses the use of fluconazole as a surrogate marker to predict the susceptibility of Candida spp. to voriconazole. Reference broth microdilution MIC results for 13,338 strains of Candida spp. isolated from more than 200 medical centers worldwide were used. Voriconazole MICs and interpretive categories (susceptible, < or =1 microg/ml; susceptible dose dependent, 2 microg/ml; resistant, > or =4 microg/ml) were compared with those of fluconazole by regression statistics and error rate bounding analyses. For all 13,338 isolates, the absolute categorical agreement was 91.6% (false susceptible or very major error [VME], 0.0%). Since voriconazole is 16- to 32-fold more potent than fluconazole, the performance of fluconazole as a surrogate marker for voriconazole susceptibility was improved by designating those isolates with fluconazole MICs of < or =32 microg/ml as being susceptible to voriconazole, resulting in a categorical agreement of 97% with 0.1% VME. Clinical laboratories performing antifungal susceptibility testing of fluconazole against Candida spp. can reliably use these results as surrogate markers until commercial FDA-approved voriconazole susceptibility tests become available.

  12. Genotyping and antifungal susceptibility testing of multiple Malassezia pachydermatis isolates from otitis and dermatitis cases in pets: is it really worth the effort?

    PubMed

    Álvarez-Pérez, Sergio; García, Marta E; Peláez, Teresa; Blanco, José L

    2016-01-01

    A total of 216 colonies of Malassezia pachydermatis from 28 cases of fungal otitis or dermatitis in pets were genotyped by M13 fingerprinting and tested for antifungal susceptibility. A huge genetic diversity was found (157 M13 types in total), with all animals having a polyclonal pattern of infection (5.4 ± 1.5 genotypes/sample). Furthermore, analysis of molecular variance (AMOVA) revealed that most genetic diversity (44%) was found at the within sample level. In contrast, variability in antifungal susceptibility among isolates from the same sample was less important, with different M13 types displaying in most cases identical or very similar MIC results. Most isolates displayed high in vitro susceptibility to amphotericin B, terbinafine and all azoles tested except fluconazole, for which MIC values were always ≥4 μg/ml and a 26.9% of isolates displayed values ≥32 μg/ml. We conclude that although characterization of multiple yeast isolates results in a considerable increase in laboratory workload and expenses, it may help to get a better understanding of the epidemiology of M. pachydermatis in a given patient population.

  13. Susceptibilities of Different Test Systems from Maize (Zea mays), Poa annua, and Festuca rubra to Herbicides That Inhibit the Enzyme Acetyl-Coenzyme A Carboxylase

    PubMed

    Herbert; Cole; Pallett; Harwood

    1996-06-01

    The susceptibilities of maize (Zea mays cv. Champ) and two graminicide-resistant grass species, Poa annua (annual meadow grass) and Festuca rubra (red fescue), to two aryloxyphenoxypropionates (quizalofop and fluazifop) and a cyclohexanedione (sethoxydim) graminicide were evaluated in leaf blades and isolated chloroplasts, and by assaying acetyl-coenzyme A carboxylase (ACCase) in desalted leaf homogenates. The graminicide resistance of P. annua and F. rubra appeared to be at the level of ACCase. Festuca rubra ACCase was highly insensitive and P. annua ACCase was partially insensitive to the graminicides that were tested. Fatty acid synthesis in isolated maize chloroplasts was more susceptible to inhibition than was ACCase activity from whole leaves. There was a smaller difference in graminicide sensitivity between these two test systems in P. annua. The developmental pattern of ACCase specific activity and its inhibition by quizalofop was measured in maize and P. annua leaf blades. There was an age-dependent increase in the sensitivity of maize leaf ACCase activity to inhibition by quizalofop. Together with the greater susceptibility of chloroplasts compared with leaf homogenates this could imply that a graminicide-insensitive (extrachloroplastic) ACCase isoform is less highly expressed in older leaves. Poa annua ACCase did not significantly alter in sensitivity as leaves aged, consistent with the smaller difference in the level of inhibition between chloroplasts and leaf homogenates in this species. A small pyruvate carboxylase activity was detected in maize leaves after 9 days. By 38 days, when leaves were senescing, pyruvate carboxylase activity predominated over ACCase.

  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. Clinical Impact of MALDI-TOF MS Identification and Rapid Susceptibility Testing on Adequate Antimicrobial Treatment in Sepsis with Positive Blood Cultures

    PubMed Central

    Verroken, Alexia; Defourny, Lydwine; le Polain de Waroux, Olivier; Belkhir, Leïla; Laterre, Pierre-François; Delmée, Michel; Glupczynski, Youri

    2016-01-01

    Shortening the turn-around time (TAT) of positive blood culture (BC) identification (ID) and susceptibility results is essential to optimize antimicrobial treatment in patients with sepsis. We aimed to evaluate the impact on antimicrobial prescription of a modified workflow of positive BCs providing ID and partial susceptibility results for Enterobacteriaceae (EB), Pseudomonas aeruginosa and Staphylococcus aureus on the day of BC positivity detection. This study was divided into a pre-intervention period (P0) with a standard BC workflow followed by 2 intervention periods (P1, P2) with an identical modified workflow. ID was performed with MALDI-TOF MS from blood, on early or on overnight subcultures. According to ID results, rapid phenotypic assays were realized to detect third generation cephalosporin resistant EB/P. aeruginosa or methicillin resistant S. aureus. Results were transmitted to the antimicrobial stewardship team for patient’s treatment revision. Times to ID, to susceptibility results and to optimal antimicrobial treatment (OAT) were compared across the three study periods. Overall, 134, 112 and 154 positive BC episodes in P0, P1 and P2 respectively were included in the analysis. Mean time to ID (28.3 hours in P0) was reduced by 65.3% in P1 (10.2 hours) and 61.8% in P2 (10.8 hours). Mean time to complete susceptibility results was reduced by 27.5% in P1 and 27% in P2, with results obtained after 32.4 and 32.6 hours compared to 44.7 hours in P0. Rapid tests allowed partial susceptibility results to be obtained after a mean time of 11.8 hours in P1 and 11.7 hours in P2. Mean time to OAT was decreased to 21.6 hours in P1 and to 17.9 hours in P2 compared to 36.1 hours in P0. Reducing TAT of positive BC with MALDI-TOF MS ID and rapid susceptibility testing accelerated prescription of targeted antimicrobial treatment thereby potentially improving the patients’ clinical outcome. PMID:27228001

  16. Clinical Impact of MALDI-TOF MS Identification and Rapid Susceptibility Testing on Adequate Antimicrobial Treatment in Sepsis with Positive Blood Cultures.

    PubMed

    Verroken, Alexia; Defourny, Lydwine; le Polain de Waroux, Olivier; Belkhir, Leïla; Laterre, Pierre-François; Delmée, Michel; Glupczynski, Youri

    2016-01-01

    Shortening the turn-around time (TAT) of positive blood culture (BC) identification (ID) and susceptibility results is essential to optimize antimicrobial treatment in patients with sepsis. We aimed to evaluate the impact on antimicrobial prescription of a modified workflow of positive BCs providing ID and partial susceptibility results for Enterobacteriaceae (EB), Pseudomonas aeruginosa and Staphylococcus aureus on the day of BC positivity detection. This study was divided into a pre-intervention period (P0) with a standard BC workflow followed by 2 intervention periods (P1, P2) with an identical modified workflow. ID was performed with MALDI-TOF MS from blood, on early or on overnight subcultures. According to ID results, rapid phenotypic assays were realized to detect third generation cephalosporin resistant EB/P. aeruginosa or methicillin resistant S. aureus. Results were transmitted to the antimicrobial stewardship team for patient's treatment revision. Times to ID, to susceptibility results and to optimal antimicrobial treatment (OAT) were compared across the three study periods. Overall, 134, 112 and 154 positive BC episodes in P0, P1 and P2 respectively were included in the analysis. Mean time to ID (28.3 hours in P0) was reduced by 65.3% in P1 (10.2 hours) and 61.8% in P2 (10.8 hours). Mean time to complete susceptibility results was reduced by 27.5% in P1 and 27% in P2, with results obtained after 32.4 and 32.6 hours compared to 44.7 hours in P0. Rapid tests allowed partial susceptibility results to be obtained after a mean time of 11.8 hours in P1 and 11.7 hours in P2. Mean time to OAT was decreased to 21.6 hours in P1 and to 17.9 hours in P2 compared to 36.1 hours in P0. Reducing TAT of positive BC with MALDI-TOF MS ID and rapid susceptibility testing accelerated prescription of targeted antimicrobial treatment thereby potentially improving the patients' clinical outcome.

  17. Susceptibility testing of extensively drug-resistant and pre-extensively drug-resistant Mycobacterium tuberculosis against levofloxacin, linezolid, and amoxicillin-clavulanate.

    PubMed

    Ahmed, Imran; Jabeen, Kauser; Inayat, Raunaq; Hasan, Rumina

    2013-06-01

    Pakistan is a high-burden country for tuberculosis (TB). The emergence and increasing incidence of extensively drug-resistant (XDR) TB has been reported in Pakistan. Similarly, the prevalence of multidrug-resistant TB infections with fluoroquinolone resistance (pre-XDR) is also increasing. To treat these infections, local drug susceptibility patterns of alternate antituberculosis agents, including levofloxacin (LVX), linezolid (LZD), and amoxicillin-clavulanate (AMC), is urgently needed. The aim of this study was to determine the susceptibility frequencies of drug-resistant (DR) Mycobacterium tuberculosis against LVX, LZD, and AMC. All susceptibilities were determined on Middlebrook 7H10 agar. A critical concentration was used for LVX (1 μg/ml), whereas MICs were determined for LZD and AMC. M. tuberculosis H37Rv was used as a control strain. A total of 102 M. tuberculosis isolates (XDR, n = 59; pre-XDR, n = 43) were tested. Resistance to LVX was observed in 91.2% (93/102). Using an MIC value of 0.5 μg/ml as a cutoff, resistance to LZD (MIC ≥ 1 μg/ml) was noted in 5.9% (6/102). Although the sensitivity breakpoints are not established for AMC, the MIC values were high (>16 μg/ml) in 97.1% (99/102). Our results demonstrate that LZD may be effective for the treatment of XDR and pre-XDR cases from Pakistan. High resistance rates against LVX in our study suggest the use of this drug with caution for DR-TB cases from this area. Drug susceptibility testing against LVX and AMC may be helpful in complicated and difficult-to-manage cases.

  18. Susceptibility Testing of Extensively Drug-Resistant and Pre-Extensively Drug-Resistant Mycobacterium tuberculosis against Levofloxacin, Linezolid, and Amoxicillin-Clavulanate

    PubMed Central

    Ahmed, Imran; Jabeen, Kauser; Inayat, Raunaq

    2013-01-01

    Pakistan is a high-burden country for tuberculosis (TB). The emergence and increasing incidence of extensively drug-resistant (XDR) TB has been reported in Pakistan. Similarly, the prevalence of multidrug-resistant TB infections with fluoroquinolone resistance (pre-XDR) is also increasing. To treat these infections, local drug susceptibility patterns of alternate antituberculosis agents, including levofloxacin (LVX), linezolid (LZD), and amoxicillin-clavulanate (AMC), is urgently needed. The aim of this study was to determine the susceptibility frequencies of drug-resistant (DR) Mycobacterium tuberculosis against LVX, LZD, and AMC. All susceptibilities were determined on Middlebrook 7H10 agar. A critical concentration was used for LVX (1 μg/ml), whereas MICs were determined for LZD and AMC. M. tuberculosis H37Rv was used as a control strain. A total of 102 M. tuberculosis isolates (XDR, n = 59; pre-XDR, n = 43) were tested. Resistance to LVX was observed in 91.2% (93/102). Using an MIC value of 0.5 μg/ml as a cutoff, resistance to LZD (MIC ≥ 1 μg/ml) was noted in 5.9% (6/102). Although the sensitivity breakpoints are not established for AMC, the MIC values were high (>16 μg/ml) in 97.1% (99/102). Our results demonstrate that LZD may be effective for the treatment of XDR and pre-XDR cases from Pakistan. High resistance rates against LVX in our study suggest the use of this drug with caution for DR-TB cases from this area. Drug susceptibility testing against LVX and AMC may be helpful in complicated and difficult-to-manage cases. PMID:23507286

  19. Evaluation of virulence factors and antifungal susceptibility patterns of different Candida species isolated from the female camel (Camelus dromedarius) genital tract.

    PubMed

    Sharifzadeh, Aghil; Soltani, Minoo; Shokri, Hojjatollah

    2015-08-01

    The purposes of this study were to investigate the enzymatic activity of different Candida species and their antifungal susceptibility patterns. The study involved a total of 83 isolates of Candida from the genital tract of the female Camelus dromedarius. After species identification, the isolates were analysed for the production/activity of phospholipase, proteinase and haemolysin. In addition, the agar disc diffusion method was performed on the basis of CLSI guidelines M44-A2 protocol for antifungal susceptibility testing. All the isolates were able to produce phospholipase, proteinase and haemolysin. A total of 35.48%, 87.09% and 64.51% of C. albicans isolates exhibited very high phospholipase, proteinase and haemolytic activities, respectively, whereas very high phospholipase, proteinase and haemolytic activities were determined in 5.76%, 23.07% and 45.16% of non-C. albicans isolates respectively. Overall, 61 (73.5%) of Candida isolates were susceptible to fluconazole, 70 (84.3%) susceptible to clotrimazole, 82 (98.8%) susceptible to voriconazole, 76 (91.6%) susceptible to itraconazole, 75 (90.4%) susceptible to ketoconazole, 83 (100%) susceptible to amphotericin B, 81 (97.6%) susceptible to nystatin and 36 (43.4%) susceptible to flucytosine. Candida isolates showed higher haemolytic activity than that of other secreted hydrolases among vaginal Candida species. In addition, amphotericin B was the most in vitro effective antifungal drug and flucytosine had the poorest activity under such conditions.

  20. Strategy for rapid identification and antibiotic susceptibility testing of gram-negative bacteria directly recovered from positive blood cultures using the Bruker MALDI Biotyper and the BD Phoenix system.

    PubMed

    Wimmer, Jana L; Long, S Wesley; Cernoch, Patricia; Land, Geoffrey A; Davis, James R; Musser, James M; Olsen, Randall J

    2012-07-01

    Decreasing the time to species identification and antibiotic susceptibility determination of strains recovered from patients with bacteremia significantly decreases morbidity and mortality. Herein, we validated a method to identify Gram-negative bacteria directly from positive blood culture medium using the Bruker MALDI Biotyper and to rapidly perform susceptibility testing using the BD Phoenix.

  1. Is a New Standard Needed for Diffusion Methods for In Vitro Susceptibility Testing of Fosfomycin against Pseudomonas aeruginosa?

    PubMed Central

    Díez-Aguilar, María; Martínez-García, Laura; Morosini, María Isabel

    2015-01-01

    We analyzed fosfomycin susceptibility results in Pseudomonas aeruginosa clinical isolates obtained by MIC gradient strips and disk diffusion methods using two different inocula, 108 and 106 CFU/ml, and compared them to the agar dilution reference method. Essential and categorical agreements were 93.6% and 95%, respectively, for the 106 CFU/ml alternative inoculum, and they were 67.6% and 78.2%, respectively, for the standard inoculum (108 CFU/ml). The use of the 106 CFU/ml inoculum improves the agreement values and inhibition zone readings. PMID:26643341

  2. Temporomandibular joint sounds and disc dislocations incidence after orotracheal intubation.

    PubMed

    Rodrigues, Estela T; Suazo, Iván C; Guimarães, Antonio S

    2009-01-01

    The aim of this study was to analyze the temporomandibular joint (TMJ) disc displacement and articular sounds incidence after orotracheal intubation. A prospective cohort study was conducted in the Hospital Universitário do Oeste do Paraná (HUOP), in Cascavel, Brazil. 100 patients (aged 14-74 years, mean 44 years), 34 male and 66 female, in need of surgical procedure with orotracheal intubation were evaluated. The anterior disc displacement with reduction incidence and the nonclassifiable sounds incidence by the Research Diagnostic Criteria Axis I was evaluated in all patients after orotracheal intubation. The patients was evaluated one day before and until two days after the procedure. Eight percent present with anterior disc displacement with reduction and 10% presented nonclassifiable sounds after the orotracheal intubation. There was no correlation of any kind regarding gender related influence in the incidence of disc dislocations (P = 0.2591) and TMJ sounds (P = 0.487). Although anterior disc dislocations and TMJ sounds after anesthetic with orotracheal intubation presented a low incidence (8%-10%), it is recommended that the evaluation of TMJ signs and symptoms be done before the anesthetic procedure to take care with susceptible patients manipulation.

  3. Optical Screening for Rapid Antimicrobial Susceptibility Testing and for Observation of Phenotypic Diversity among Strains of the Genetically Clonal Species Bacillus anthracis.

    PubMed

    McLaughlin, Heather P; Gargis, Amy S; Michel, Pierre; Sue, David; Weigel, Linda M

    2017-03-01

    During high-impact events involving Bacillus anthracis, such as the Amerithrax incident of 2001 or the anthrax outbreaks in Russia and Sweden in 2016, critical decisions to reduce morbidity and mortality include rapid selection and distribution of effective antimicrobial agents for treatment and postexposure prophylaxis. Detection of antimicrobial resistance currently relies on a conventional broth microdilution method that requires a 16- to 20-h incubation time for B. anthracis Advances in high-resolution optical screening offer a new technology to more rapidly evaluate antimicrobial susceptibility and to simultaneously assess the growth characteristics of an isolate. Herein, we describe a new method developed and evaluated as a rapid antimicrobial susceptibility test for B. anthracis This method is based on automated digital time-lapse microscopy to observe the growth and morphological effects of relevant antibiotics with an optical screening instrument, the oCelloScope. B. anthracis strains were monitored over time in the presence or absence of penicillin, ciprofloxacin, or doxycycline. Susceptibility to each antibiotic was determined in ≤4 h, 75 to 80% less than the time required for conventional methods. Time-lapse video imaging compiled from the optical screening images revealed unexpected differences in growth characteristics among strains of B. anthracis, which is considered to be a clonal organism. This technology provides a new approach for rapidly detecting phenotypic antimicrobial resistance and for documenting growth attributes that may be beneficial in the further characterization of individual strains.

  4. Lumbar herniated disc: spontaneous regression

    PubMed Central

    Yüksel, Kasım Zafer

    2017-01-01

    Background Low back pain is a frequent condition that results in substantial disability and causes admission of patients to neurosurgery clinics. To evaluate and present the therapeutic outcomes in lumbar disc hernia (LDH) patients treated by means of a conservative approach, consisting of bed rest and medical therapy. Methods This retrospective cohort was carried out in the neurosurgery departments of hospitals in Kahramanmaraş city and 23 patients diagnosed with LDH at the levels of L3−L4, L4−L5 or L5−S1 were enrolled. Results The average age was 38.4 ± 8.0 and the chief complaint was low back pain and sciatica radiating to one or both lower extremities. Conservative treatment was administered. Neurological examination findings, durations of treatment and intervals until symptomatic recovery were recorded. Laségue tests and neurosensory examination revealed that mild neurological deficits existed in 16 of our patients. Previously, 5 patients had received physiotherapy and 7 patients had been on medical treatment. The number of patients with LDH at the level of L3−L4, L4−L5, and L5−S1 were 1, 13, and 9, respectively. All patients reported that they had benefit from medical treatment and bed rest, and radiologic improvement was observed simultaneously on MRI scans. The average duration until symptomatic recovery and/or regression of LDH symptoms was 13.6 ± 5.4 months (range: 5−22). Conclusions It should be kept in mind that lumbar disc hernias could regress with medical treatment and rest without surgery, and there should be an awareness that these patients could recover radiologically. This condition must be taken into account during decision making for surgical intervention in LDH patients devoid of indications for emergent surgery. PMID:28119770

  5. Evolution of gas in debris discs

    NASA Astrophysics Data System (ADS)

    Kral, Quentin; Wyatt, Mark; Pringle, Jim

    2015-12-01

    A non negligible quantity of gas has been discovered in an increasing number of debris disc systems. ALMA high sensitivity and high resolution is changing our perception of the gaseous component of debris discs as CO is discovered in systems where it should be rapidly photodissociated. It implies that there is a replenishment mechanism and that the observed gas is secondary. Past missions such as Herschel probed the atomic part of the gas through O I and C II emission lines. Gas science in debris discs is still in its infancy, and these new observations raise a handful of questions concerning the mechanisms to create the gas and about its evolution in the planetary system when it is released. The latter question will be addressed in this talk as a self-consistent gas evolution scenario is proposed and is compared to observations for the peculiar case of β Pictoris.Our model proposes that carbon and oxygen within debris discs are created due to photodissociation of CO which is itself created from the debris disc dust (due to grain-grain collisions or photodesorption). The evolution of the carbon atoms is modelled as viscous spreading, with viscosity parameterised using an α model. The temperature, ionisation fraction and population levels of carbon are followed with a PDR model called Cloudy, which is coupled to the dynamical viscous α model. Only carbon gets ionised due to its lower ionisation potential than oxygen. The carbon gas disc can end up with a high ionisation fraction due to strong FUV radiation field. A high ionisation fraction means that the magnetorotational instability (MRI) is very active, so that α is very high. Gas density profiles can be worked out for different input parameters such as the α value, the CO input rate, the location of the input and the incoming radiation field. Observability predictions can be made for future observations, and our model is tested on β Pictoris observations. This new gas evolution model fits the carbon and CO

  6. Scaling from discs to pleated devices.

    PubMed

    Giglia, Sal; Yavorsky, David

    2007-01-01

    Membrane discs offer a convenient format for evaluating membrane performance in normal flow filtration. However, while pleated devices of different sizes tend to scale in close proportion to their contained areas, they do not necessarily scale in direct proportion from flat discs. The objectives of this study are to quantify differences in performance among sterilizing-grade membrane devices as a function of device type and size, to develop an understanding of the factors that affect device scalability, and to develop a mathematical model to predict a cartridge-to-disc scalability factor based on membrane properties and porous support properties and dimensions. Measured and predicted normalized water permeability scalability factors for seven types of pleated cartridges, including 0.1-micro and 0.2-micro rated PES, and 0.2-micro rated polyvinylidene fluoride (PVDF) sterilizing-grade filters in nominal 1-inch to 5-inch lengths, were determined. The results of this study indicate that pleated cartridge performance can be closely predicted based on 47-mm disc performance provided that a number of measured device parameters are properly accounted for, most importantly parasitic pressure losses in the filter device and plumbing connections, intrinsic membrane variability, true effective device filtration area, and the hydraulic properties of all porous support materials. Throughput scalability factors (discs to devices) tend to converge towards unity, especially for highly plugging streams. As the membrane fouls, the resistance through the membrane dominates other resistances, so the flux scales more linearly with membrane area and the overall scaling factor becomes close to one. The results of throughput tests on seven different cartridge types and five different challenge streams (with widely varying fouling characteristics) show that most of the throughput scaling factors were within +/-10% of 1.0. As part of this study, the effects of pressure and temperature were

  7. Susceptibility to UV damage in Impatiens capensis (Balsaminaceae): testing for opportunity costs to shade-avoidance and population differentiation.

    PubMed

    Dixon, P; Weinig, C; Schmitt, J

    2001-08-01

    Plastic increases in leaf secondary compounds may be an adaptive strategy that reduces the damaging effects of high-energy, ultraviolet radiation (UV). Here, we examine (1) the relationship between fitness and anthocyanin and flavonoid concentrations in experimental, UV environments, (2) the effects of UV on Impatiens capensis plants derived from woodland and clearing sites, and (3) whether susceptibility to UV damage is reduced by exposure to high ratios of red : far-red wavelengths (R : FR), which also stimulate the production of leaf compounds. Seedlings from each site were exposed to either high R : FR typical of sunlight or low R : FR characteristic of foliar shade, after which plants were moved into ambient UV or UV-removal treatments. Ultraviolet radiation stimulated the production of anthocyanins and flavonoids. However, higher anthocyanin concentrations were associated with lower biomass in the UV environment. Relative to the clearing population, reproductive output of the woodland population was more detrimentally affected by exposure to UV, despite its higher concentration of anthocyanins. Increased anthocyanin production may therefore be a stress response rather than an adaptive one. The greater tolerance of the clearing population to UV suggests that populations with an evolutionary history of UV exposure evolve mechanisms to limit damage. The R : FR pretreatments did not influence susceptibility to UV damage.

  8. Molecular characterization of extended-spectrum beta-lactamases and its correlation with clinical laboratory standards institute interpretive criteria for disk diffusion susceptibility testing in enterobacteriaceae isolates in Thaialnd.

    PubMed

    Tangkoskul, Teerawit; Tiengrim, Surapee; Onsomang, Supiluck; Pati, Naratchaphan; Aswapokee, Nalinee; Thamlikitkul, Visanu; Chayakulkeeree, Methee

    2012-11-01

    We performed extended-spectrum beta-lactamase (ESBL) phenotypic testing and molecular characterization of three ESBL genes (TEM, SHV and CTX-M) and susceptibility testing by Clinical Laboratory Standards Institute (CLSI) disk diffusion method against three cephalosporins (ceftriaxone, ceftazidime, cefepime) and a cephamycin (cefoxitin) among 128 Thai Escherichia coli and 84 Thai Klebsiella pneumoniae clinical isolates. ESBL production was discovered in 62% of E. coli and 43% of K. pneumoniae isolates. All isolates susceptible to ceftriaxone were ESBL-negative. Nearly all isolates non-susceptible to ceftriaxone, ceftazidime and cefepime produced ESBL; the presence of CTX-M genes in the isolates correlated with a ceftriaxone non-susceptible phenotype. Thirty-nine of 83 isolates (47%) of ceftazidime-susceptible E. coli and 50 of 99 isolates (50.5%) of cefepime-susceptible E. coli were ESBL-producing. SHV-type beta-lactamase genes were more prevalent among K. pneumoniae than E. coli isolates. CTX-M was the major ESBL gene harbored by ESBL-producers in both E. coli and K. pneumoniae isolates. Non-CTX-M ESBL-producers were found only among K. pneumoniae isolates. This study reveals an increase in ESBL-producing Enterobacteriaceae among Thai isolates and demonstrates gaps in the current CLSI disk diffusion susceptibility guidelines; it indicates the results of ceftazidime and cefepime disk diffusion susceptibility testing using CLSI criteria should be interpreted with caution.

  9. Multiple Genetic Analysis System-Based Antibiotic Susceptibility Testing in Helicobacter pylori and High Eradication Rate With Phenotypic Resistance-Guided Quadruple Therapy.

    PubMed

    Dong, Fangyuan; Ji, Danian; Huang, Renxiang; Zhang, Fan; Huang, Yiqin; Xiang, Ping; Kong, Mimi; Nan, Li; Zeng, Xianping; Wu, Yong; Bao, Zhijun

    2015-11-01

    Antibiotics resistance in Helicobacter pylori (H. pylori) is the major factor for eradication failure. Molecular tests including fluorescence in situ hybridization, PCR-restriction fragment length polymorphism, and dual priming oligonucleotide-PCR (DPO-PCR) play critical roles in the detection of antibiotic susceptibility; however, limited knowledge is known about application of multiple genetic analysis system (MGAS) in the area of H. pylori identification and antibiotics resistance detection.The aim of this study is to determine the antibiotics resistance using different molecular tests and evaluate the treatment outcomes of E-test-based genotypic resistance.A total of 297 patients with dyspepsia complaint were recruited for gastroscopies. Ninety patients with H. pylori culture positive were randomly divided into 2 groups (test group and control group). E-test, general PCR, and MGAS assay were performed in test group. Patients in control group were treated with empirical therapy (rabeprazole + bismuth potassium citrate + amoxicillin [AMX] + clarithromycin [CLR]), whereas patients in test group received quadruple therapy based on E-test results twice daily for 14 consecutive days. The eradication effect of H. pylori was confirmed by C-urea breath test after at least 4 weeks when treatment was finished.Rapid urease test showed 46.5% (128/297) patients with H. pylori infection, whereas 30.3% (90/297) patients were H. pylori culture positive. E-test showed that H. pylori primary resistance rate to CLR, AMX, metronidazole, tetracycline, and levofloxacin (LVX) was 40.0% (18/45), 4.4% (2/45), 53.3% (24/45), 0% (0/45), and 55.6% (25/45), respectively. In addition, there are many multidrug resistant (MDR) phenotypes, and the MDR strains have higher minimum inhibitory concentration than their single-drug resistant counterparts. Considering E-test as the reference test, the sensitivities of general PCR and MGAS in detecting CLR resistance were 83.3% (15/18) and 94.4% (17

  10. Evaluating the in vitro susceptibility of bovine mastitis pathogens to a combination of kanamycin and cefalexin: Recommendations for a disk diffusion test.

    PubMed

    Pillar, C M; Goby, L; Draghi, D; Grover, P; Thornsberry, C

    2009-12-01

    Cows suffering from bovine mastitis have markedly reduced milk production because of inflammation within the udder subsequent to infection and damage from bacterial toxins. Antibiotic treatment is commonly used as a preventative and therapeutic measure for bovine mastitis. The most common pathogens include Staphylococcus aureus, various streptococci (Streptococcus dysgalactiae, Streptococcus uberis), and coliforms (Escherichia coli), which can be contracted from other infected cows or from the environment. A combination of kanamycin and cefalexin (1:1.5 wt/wt) is currently used therapeutically in Europe for the treatment of bovine mastitis, although standardized methods for the in vitro determination of the susceptibility of target pathogens have not been developed. This study evaluates the appropriate broth microdilution testing criteria for kanamycin and cefalexin administered in combination and reports the development of a disk diffusion test. At a ratio of kanamycin:cefalexin relevant to that observed in milk postadministration (10:1 wt/wt), the minimum inhibitory concentrations were determined against 307 isolates of target mastitis pathogens (staphylococci, streptococci, and E. coli). Based on achievable concentrations in milk and the resulting distribution of minimum inhibitory concentrations, preliminary broth breakpoints for kanamycin/cefalexin (10:1 fixed ratio) of susceptible, 16/1.6 microg/mL intermediate, and >or=32/3.2 microg/mL resistant were applied to evaluated staphylococci, streptococci, and E. coli. Parallel testing by disk diffusion and resulting error-rate bounded analysis using a combined disk concentration of 30 microg of kanamycin and 15 microg of cefalexin resulted in the establishment of preliminary disk interpretive breakpoints of >or=20 mm susceptible, 18 to 19 mm intermediate, and

  11. Imaginal disc regeneration takes flight.

    PubMed

    Hariharan, Iswar K; Serras, Florenci

    2017-04-01

    Drosophila imaginal discs, the larval precursors of adult structures such as the wing and leg, are capable of regenerating after damage. During the course of regeneration, discs can sometimes generate structures that are appropriate for a different type of disc, a phenomenon termed transdetermination. Until recently, these phenomena were studied by physically fragmenting discs and then transplanting them into the abdomens of adult female flies. This field has experienced a renaissance following the development of genetic ablation systems that can damage precisely defined regions of the disc without the need for surgery. Together with more traditional approaches, these newer methods have generated many novel insights into wound healing, the mechanisms that drive regenerative growth, plasticity during regeneration and systemic effects of tissue damage and regeneration.

  12. Knowledge and practices of laboratory workers on standardized antimicrobial susceptibility testing and biosafety practices to prevent the spread of superbugs in Pakistan.

    PubMed

    Ghanchi, Najia K; Khan, Erum; Farooqi, Joveria Q; Fasih, Naima; Dojki, Maqboola; Hughes, Molly A

    2014-09-01

    A cross-sectional survey using structured questionnaire was conducted to assess practices of microbiological laboratories working with pathogens. Forty-eight laboratory workers (50%) agreed that laboratory methods to detect antimicrobial resistance are not standardized in Pakistan, and 6% of the laboratory workers were not aware of the standardization of antimicrobial susceptibility testing in Pakistan. Reported rates of awareness regarding the role of waste disposal, disinfection, and handwashing in limiting the spread of antimicrobial resistance were 75%, 42%, and 81%, respectively. Our results provide baseline data for planning programs to train, supervise, and improve the operational quality of microbiological laboratories nationwide to prevent the spread of superbugs.

  13. Multicenter laboratory evaluation of the bioMérieux Vitek antimicrobial susceptibility testing system with 11 antimicrobial agents versus members of the family Enterobacteriaceae and Pseudomonas aeruginosa.

    PubMed Central

    Doern, G V; Brueggemann, A B; Perla, R; Daly, J; Halkias, D; Jones, R N; Saubolle, M A

    1997-01-01

    A four-center study in which a total of 1,082 recent clinical isolates of members of the family Enterobacteriaceae and Pseudomonas aeruginosa were examined versus 11 antimicrobial agents with the bioMérieux Vitek susceptibility test system (Hazelwood, Mo.) and the GNS-F6 card was conducted. In addition, a challenge set consisting of the same 200 organisms was examined in each of the four participating laboratories. Results obtained with the Vitek system were compared to MICs determined by a standardized broth microdilution method. For purposes of comparison, susceptibility categories (susceptible, intermediate, or resistant) were assigned on the basis of the results of both methods. The result of the broth microdilution test was considered definitive. The total category error rate with the Vitek system and the recent clinical isolates (11,902 organism-antimicrobial comparisons) was 4.5%, i.e., 1.7% very major errors, 0.9% major errors, and 1.9% minor errors. The total category error rate calculated from tests performed with the challenge set (i.e., 8,800 organism-antimicrobial comparisons) was 5.9%, i.e., 2.2% very major errors, 1.1% major errors, and 2.6% minor errors. Very major error rates higher than the totals were noted with Enterobacter cloacae versus ampicillin-sulbactam, aztreonam, ticarcillin, and ticarcillin-clavulanate and with P. aeruginosa versus mezlocillin, ticarcillin, and ticarcillin-clavulanate. Major error rates higher than the averages were observed with Proteus mirabilis versus imipenem and with Klebsiella pneumoniae versus ofloxacin. Excellent overall interlaboratory reproducibility was observed with the Vitek system. The importance of inoculum size as a primary determinant in the accuracy of susceptibility test results with the Vitek system was clearly demonstrated in this study. Specifically, when an inoculum density fourfold higher than that recommended by the manufacturer was used, high rates of false resistance results were obtained

  14. Intraoral micro-identification discs.

    PubMed

    Hansen, R W

    1991-12-01

    Intraoral micro-identification discs have recently been utilized to provide a more permanent method of personal identification. A wafer of plastic or metal with a surface area of 2.5 to 5 mm2 and carrying identifying numbers and/or letters (indicia) is bonded to the buccal enamel surface of the posterior teeth. Personal identification can occur after the I.D. disc is identified and the indicia is read. Reading of photoreduced indicia requires the aid of a microscope subsequent to the removal of the microdisc. In situ reading of disc indicia is possible using low power handheld magnifiers if the size of the indicia approximates 0.3 mm. Computerization is an integral part of non-custom alpha/numeric type designs, but a custom disc carries a name, address, and other specific information unique to the manufacturer. The use of a computer improves access to the database and it decreases the amount of data placed on the disc. Microdisc bases may be fabricated using a mylar type plastic or they may be manufactured from a stainless steel blank. Plastic discs are constructed with an internal sandwich containing the photo-reduced indicia. Metal discs are marked with a photochemical etch or engraved with a computer driven YAG laser. Attachment of the disc to the enamel surface is accomplished by conventional etching and bonding techniques and are typically bonded to the buccal surface of the maxillary first permanent molar or the second primary molar. Clear composite bonding material covers the disc so that salivary contamination does not result in degradation of the indicia. Orthodontic style discs with a mesh back carry laser written information that may be cemented with conventional orthodontic bonding cement. Standardization of the indicia and overall design is considered to be an important aspect of patient and professional acceptance.

  15. Evaluation of the PREVI® Isola automated seeder system compared to reference manual inoculation for antibiotic susceptibility testing by the disk diffusion method.

    PubMed

    Le Page, S; van Belkum, A; Fulchiron, C; Huguet, R; Raoult, D; Rolain, J-M

    2015-09-01

    The disk diffusion (DD) method remains the most popular manual technique for antibiotic susceptibility testing (AST) in clinical microbiology laboratories. This is because of its simplicity, reproducibility, and limited cost compared to (automated) microdilution systems, which are usually less sensitive at detecting certain important mechanisms of resistance. Here, we evaluate the PREVI® Isola automated seeder system using a new protocol for spreading bacterial suspensions (eight deposits of calibrated inocula of bacteria, followed by two rounds of rotation) in comparison with manual DD reference testing on a large series of clinical and reference strains. The average time required for seeding one agar plate for DD with this new protocol was 51 s per plate, i.e., 70 agar plates/h. Reproducibility and repeatability was assessed on three reference and three randomly chosen clinical strains, as usually requested by the European Committee on Antimicrobial Susceptibility Testing (EUCAST), and was excellent compared to the manual method. The standard deviations of zones of growth inhibition showed no statistical discrimination. The correlation between the two methods, assessed using 294 clinical isolates and a panel of six antibiotics (n = 3,528 zones of growth inhibition measured), was excellent, with a correlation coefficient of 0.977. The new PREVI® Isola protocol adapted for DD had a sensitivity of 99 % and a specificity of 100 % compared to the manual technique for interpreting DD as recommended by the EUCAST.

  16. Resistance to Second-Line Antituberculosis Drugs and Delay in Drug Susceptibility Testing among Multidrug-Resistant Tuberculosis Patients in Shanghai

    PubMed Central

    Yuan, Zhengan; Shen, Xin; Wu, Jie; Wu, Zheyuan

    2016-01-01

    Introduction. Second-line antituberculosis drugs (SLDs) are used for treating multidrug-resistant tuberculosis (MDR-TB). Prolonged delays before confirming MDR-TB with drug susceptibility testing (DST) could result in transmission of drug-resistant strains and inappropriate use of SLDs, thereby increasing the risk of resistance to SLDs. This study investigated the diagnostic delay in DST and prevalence of baseline SLD resistance in Shanghai and described the distribution of SLD resistance with varied delays to DST. Methods. All registered patients from 2011 to 2013 in Shanghai were enrolled. Susceptibility to ofloxacin, amikacin, kanamycin, and capreomycin was tested. Total delay in DST completion was measured from the onset of symptoms to reporting DST results. Results. Resistance to SLDs was tested in 217 of the 276 MDR-TB strains, with 118 (54.4%) being resistant to at least one of the four SLDs. The median total delay in DST was 136 days. Patients with delay longer than median days were roughly twice more likely to have resistance to at least one SLD (OR 2.22, 95% CI 1.19–4.11). Conclusions. During prolonged delay in DST, primary and acquired resistance to SLDs might occur more frequently. Rapid diagnosis of MDR-TB, improved nosocomial infection controls, and regulated treatment are imperative to prevent SLD resistance. PMID:27652260

  17. In vitro susceptibility of filamentous fungi to itraconazole, voriconazole and posaconazole by Clinical and Laboratory Standards Institute reference method and E-test.

    PubMed

    Kondori, N; Svensson, E; Mattsby-Baltzer, I

    2011-09-01

    The use of anti-fungal agents has increased dramatically in recent years and new drugs have been developed. Several methods are available for determinations of their specific biological activities, i.e. the standard method for minimum inhibitory concentration-determination is described in M-38 [Clinical and Laboratory Standards Institute document M-38 (CLSI M-38)]. However, alternative methods, such as the E-test, are currently available in Mycology laboratories. The susceptibilities of clinical isolates of Aspergillus spp. (n = 29), Fusarium spp. (n = 5), zygomycetes (n = 21) and Schizophyllum (n = 1) were determined for itraconazole, voriconazole and posaconazole, using the CLSI M-38-A broth dilution method and also by the E-test. A good overall agreement (83.7%) between the two methods for all drugs and organisms was observed. Analyses of voriconazole showed a better agreement (93%) between the methods than posaconazole and itraconazole (85% and 74% respectively). Aspergillus spp. were the most susceptible fungi to the anti-fungal agents tested in this study. Posaconazole was the most active drug against filamentous fungi in vitro, followed by itraconazole and voriconazole. The latter (voriconazole) demonstrated no significant in vitro activity against zygomycetes.

  18. Resistance to Second-Line Antituberculosis Drugs and Delay in Drug Susceptibility Testing among Multidrug-Resistant Tuberculosis Patients in Shanghai.

    PubMed

    Chen, Yong; Yuan, Zhengan; Shen, Xin; Wu, Jie; Wu, Zheyuan; Xu, Biao

    2016-01-01

    Introduction. Second-line antituberculosis drugs (SLDs) are used for treating multidrug-resistant tuberculosis (MDR-TB). Prolonged delays before confirming MDR-TB with drug susceptibility testing (DST) could result in transmission of drug-resistant strains and inappropriate use of SLDs, thereby increasing the risk of resistance to SLDs. This study investigated the diagnostic delay in DST and prevalence of baseline SLD resistance in Shanghai and described the distribution of SLD resistance with varied delays to DST. Methods. All registered patients from 2011 to 2013 in Shanghai were enrolled. Susceptibility to ofloxacin, amikacin, kanamycin, and capreomycin was tested. Total delay in DST completion was measured from the onset of symptoms to reporting DST results. Results. Resistance to SLDs was tested in 217 of the 276 MDR-TB strains, with 118 (54.4%) being resistant to at least one of the four SLDs. The median total delay in DST was 136 days. Patients with delay longer than median days were roughly twice more likely to have resistance to at least one SLD (OR 2.22, 95% CI 1.19-4.11). Conclusions. During prolonged delay in DST, primary and acquired resistance to SLDs might occur more frequently. Rapid diagnosis of MDR-TB, improved nosocomial infection controls, and regulated treatment are imperative to prevent SLD resistance.

  19. [Species distribution and antifungal susceptibility of Candida spp. causing superficial mycosis. Coro, Falcon state, Venezuela].

    PubMed

    Saúl-García, Yotsabeth; Humbría-García, Leyla; Hernández-Valles, Rosaura

    2015-09-01

    Candida species other than C. albicans are often described as causative agents of superficial mycosis and are more resistant to treatment with azoles. In order to determine the distribution of species and in vitro antifungal susceptibility of Candida spp., one ambispective study, which analyzed 18 yeast isolates obtained from samples from patients diagnosed with superficial mycosis, was performed. Taxonomic identification was performed by macroscopic visualization of the growth characteristics in chromogenic agar and by conventional methods. The susceptibility to fluconazole and voriconazole was evaluated by the disc diffusion method. Most of the isolates (88.8%), came from nail samples. C. parapsilosis was the most common species, followed by C. tropicalis, C. albicans and C. krusei, which confirmed the prevalence of non-albicans species as a cause of superficial mycoses. The pattern of susceptibility to fluconazole and voriconazole was similar: all isolates of C. parapsilosis and C. albicans were susceptible, while 83.3% of C. tropicalis showed sensitivity to both antifungals. C. krusei, fluconazole-resistant species showed intermediate susceptibility io voriconazole. The use of chromogenic agar allowed to detect mixed infections in nail samples, involving Candida spp. and C. tropicalis in one case, the latter with resistance to both fluconazole and voriconazole. The results demonstrate the importance of species identification and susceptibility testing to avoid therapeutic failures in superficial mycoses.

  20. Antimicrobial Susceptibility Testing of Two Lawsonia intracellularis Isolates Associated with Proliferative Hemorrhagic Enteropathy and Porcine Intestinal Adenomatosis in South Korea▿

    PubMed Central

    Yeh, Jung-Yong; Lee, Ji-Hye; Yeh, Hye-Ryun; Kim, Aeran; Lee, Ji Youn; Hwang, Jeong-Min; Kang, Bo-Kyu; Kim, Jong-Man; Choi, In-Soo; Lee, Joong-Bok

    2011-01-01

    This study represents the first published data on antimicrobial susceptibility of Asian isolates of Lawsonia intracellularis. We assessed MICs of 16 antimicrobials for two isolates of L. intracellularis recovered from diseased pigs in South Korea, one from a finisher pig with acute proliferative hemorrhagic enteropathy in 2002 and the other from a grower pig with porcine intestinal adenomatosis in 2010. Tylosin and tilmicosin were found to be the most active against L. intracellularis both intracellularly (MICs, 0.25 to 0.5 μg/ml and 0.125 μg/ml, respectively) and extracellularly (MICs, 0.25 to 0.5 μg/ml and 1 μg/ml, respectively). PMID:21690283

  1. Experimental model of intervertebral disc degeneration by needle puncture in Wistar rats

    PubMed Central

    Issy, A.C.; Castania, V.; Castania, M.; Salmon, C.E.G.; Nogueira-Barbosa, M.H.; Bel, E. Del; Defino, H.L.A.

    2013-01-01

    Animal models of intervertebral disc degeneration play an important role in clarifying the physiopathological mechanisms and testing novel therapeutic strategies. The objective of the present study is to describe a simple animal model of disc degeneration involving Wistar rats to be used for research studies. Disc degeneration was confirmed and classified by radiography, magnetic resonance and histological evaluation. Adult male Wistar rats were anesthetized and submitted to percutaneous disc puncture with a 20-gauge needle on levels 6-7 and 8-9 of the coccygeal vertebrae. The needle was inserted into the discs guided by fluoroscopy and its tip was positioned crossing the nucleus pulposus up to the contralateral annulus fibrosus, rotated 360° twice, and held for 30 s. To grade the severity of intervertebral disc degeneration, we measured the intervertebral disc height from radiographic images 7 and 30 days after the injury, and the signal intensity T2-weighted magnetic resonance imaging. Histological analysis was performed with hematoxylin-eosin and collagen fiber orientation using picrosirius red staining and polarized light microscopy. Imaging and histological score analyses revealed significant disc degeneration both 7 and 30 days after the lesion, without deaths or systemic complications. Interobserver histological evaluation showed significant agreement. There was a significant positive correlation between histological score and intervertebral disc height 7 and 30 days after the lesion. We conclude that the tail disc puncture method using Wistar rats is a simple, cost-effective and reproducible model for inducing disc degeneration. PMID:23532265

  2. Quality control ranges for testing broth microdilution susceptibility of Flavobacterium columnare and F. psychrophilium to nine antimicrobials

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A multi-laboratory broth microdilution method trial was performed to standardize the specialized test conditions required for fish pathogens Flavobacterium columnare and F. pyschrophilum. Nine laboratories tested the quality control (QC) strains Escherichia coli ATCC 25922 and Aeromonas salmonicid...

  3. Cervical Total Disc Arthroplasty

    PubMed Central

    Basho, Rahul; Hood, Kenneth A.

    2012-01-01

    Symptomatic adjacent segment degeneration of the cervical spine remains problematic for patients and surgeons alike. Despite advances in surgical techniques and instrumentation, the solution remains elusive. Spurred by the success of total joint arthroplasty in hips and knees, surgeons and industry have turned to motion preservation devices in the cervical spine. By preserving motion at the diseased level, the hope is that adjacent segment degeneration can be prevented. Multiple cervical disc arthroplasty devices have come onto the market and completed Food and Drug Administration Investigational Device Exemption trials. Though some of the early results demonstrate equivalency of arthroplasty to fusion, compelling evidence of benefits in terms of symptomatic adjacent segment degeneration are lacking. In addition, non-industry-sponsored studies indicate that these devices are equivalent to fusion in terms of adjacent segment degeneration. Longer-term studies will eventually provide the definitive answer. PMID:24353955

  4. Daptomycin Bactericidal Activity and Correlation between Disk and Broth Microdilution Method Results in Testing of Staphylococcus aureus Strains with Decreased Susceptibility to Vancomycin

    PubMed Central

    Sader, Helio S.; Fritsche, Thomas R.; Jones, Ronald N.

    2006-01-01

    A total of 207 Staphylococcus aureus strains, including 105 well-characterized strains with decreased susceptibility to vancomycin (17 vancomycin-intermediate S. aureus [VISA] and 88 heteroresistant VISA [hVISA] strains) and 102 wild-type methicillin-resistant S. aureus (MRSA-WT) strains were tested by reference/standardized broth microdilution and disk diffusion methods, as well as by Etest (AB BIODISK, Solna, Sweden), against daptomycin and vancomycin. The lowest concentration of antimicrobial agent that killed ≥99.9% of the initial inoculum was defined as the minimum bactericidal concentration (MBC) endpoint, and time-kill curves were performed in selected strains to further evaluate bactericidal activity. All MRSA-WT and hVISA strains were inhibited by ≤1 μg/ml of daptomycin, while the VISA strains showed slightly higher daptomycin MICs (range, 0.5 to 4 μg/ml). All daptomycin MBC results were at the MIC or twofold higher. In contrast, 14.7% of MRSA-WT, 69.3% of hVISA, and all VISA strains showed a vancomycin MBC/MIC ratio of ≥32 or an MBC of ≥16 μg/ml (tolerant). The correlation coefficients between broth microdilution and disk diffusion method results were low for daptomycin (0.07) and vancomycin (0.11). Eight (3.8%) strains (all hVISA or VISA) were “nonsusceptible” to daptomycin by broth microdilution methods but susceptible by the disk diffusion method. For vancomycin, 35 (16.9%) strains were nonsusceptible by broth microdilution methods but susceptible by disk diffusion methods. In conclusion, daptomycin was highly bactericidal against S. aureus strains, and its bactericidal activity was not affected by decreased susceptibility to vancomycin. In contrast, many (one in seven) contemporary MRSA-WT, the majority of hVISA, and all VISA strains showed vancomycin MBC/MIC ratios consistent with tolerance, a predictor of poor clinical response. Disk diffusion tests generally failed to detect strains categorized as nonsusceptible to daptomycin or

  5. Does condylar height decrease more in temporomandibular joint nonreducing disc displacement than reducing disc displacement?

    PubMed Central

    Hu, Ying-Kai; Yang, Chi; Cai, Xie-Yi; Xie, Qian-Yang

    2016-01-01

    Abstract The aim of the study was to compare condylar height changes of anterior disc displacement with reduction (ADDwR) and anterior disc displacement without reduction (ADDwoR) in temporomandibular joint (TMJ) quantitatively, to get a better understanding of the changes in condylar height of patients with anterior disc displacement who had received no treatment, and to provide useful information for treatment protocol. This longitudinal retrospective study enrolled 206 joints in 156 patients, which were divided into ADDWR group and ADDwoR group based on magnetic resonance imaging examination. The joints were assessed quantitatively for condylar height at initial and follow-up visits. Also, both groups were further divided into 3 subgroups according to age: <15 years group, 15 to 21 years group, and 22 to 35 years group. Paired t test and independent t test were used to assess intra- and intergroup differences. The average age of the ADDwR group was 19.65 years with a mean of 9.47 months’ follow-up. The follow-up interval of the patients with ADDwoR was 7.96 months, with a mean age of 18.51 years. Condylar height in ADDwoR tended to decrease more than those in ADDwR, especially during the pubertal growth spurt and with the presence of osteoarthrosis, meaning ADDwoR could cause a severe disturbance in mandibular development. Thus, an early disc repositioning was suggested to avoid decrease in condylar height. PMID:27583909

  6. Direct-to-consumer genetic testing for addiction susceptibility: a premature commercialisation of doubtful validity and value.

    PubMed

    Mathews, Rebecca; Hall, Wayne; Carter, Adrian

    2012-12-01

    Genetic research on addiction liability and pharmacogenetic research on treatments for addiction have identified some genetic variants associated with disease risk and treatment. Genetic testing for addiction liability and treatment response has not been used widely in clinical practice because most of the genes identified only modestly predict addiction risk or treatment response. However, many of these genetic tests have been commercialized prematurely and are available direct to the consumer (DTC). The easy availability of DTC tests for addiction liability and lack of regulation over their use raises a number of ethical concerns. Of paramount concern is the limited predictive power and clinical utility of these tests. Many DTC testing companies do not provide the co