Fluorocycline TP-271 Is Potent against Complicated Community-Acquired Bacterial Pneumonia Pathogens

PubMed Central

Fyfe, Corey; O’Brien, William; Hackel, Meredith; Minyard, Mary Beth; Waites, Ken B.; Dubois, Jacques; Murphy, Timothy M.; Slee, Andrew M.; Weiss, William J.; Sutcliffe, Joyce A.

2017-01-01

ABSTRACT TP-271 is a novel, fully synthetic fluorocycline antibiotic in clinical development for the treatment of respiratory infections caused by susceptible and multidrug-resistant pathogens. TP-271 was active in MIC assays against key community respiratory Gram-positive and Gram-negative pathogens, including Streptococcus pneumoniae (MIC90 = 0.03 µg/ml), methicillin-sensitive Staphylococcus aureus (MSSA; MIC90 = 0.25 µg/ml), methicillin-resistant S. aureus (MRSA; MIC90 = 0.12 µg/ml), Streptococcus pyogenes (MIC90 = 0.03 µg/ml), Haemophilus influenzae (MIC90 = 0.12 µg/ml), and Moraxella catarrhalis (MIC90 ≤0.016 µg/ml). TP-271 showed activity (MIC90 = 0.12 µg/ml) against community-acquired MRSA expressing Panton-Valentine leukocidin (PVL). MIC90 values against Mycoplasma pneumoniae, Legionella pneumophila, and Chlamydia pneumoniae were 0.004, 1, and 4 µg/ml, respectively. TP-271 was efficacious in neutropenic and immunocompetent animal pneumonia models, generally showing, compared to the burden at the start of dosing, ~2 to 5 log10 CFU reductions against MRSA, S. pneumoniae, and H. influenzae infections when given intravenously (i.v.) and ~1 to 4 log10 CFU reductions when given orally (p.o.). TP-271 was potent against key community-acquired bacterial pneumonia (CABP) pathogens and was minimally affected, or unaffected, by tetracycline-specific resistance mechanisms and fluoroquinolone or macrolide drug resistance phenotypes. IMPORTANCE Rising resistance rates for macrolides, fluoroquinolones, and β-lactams in the most common pathogens associated with community-acquired bacterial pneumonia (CABP) are of concern, especially for cases of moderate to severe infections in vulnerable populations such as the very young and the elderly. New antibiotics that are active against multidrug-resistant Streptococcus pneumoniae and Staphylococcus aureus are needed for use in the empirical treatment of the most severe forms of this disease. TP-271 is a promising

Phages and the Evolution of Bacterial Pathogens: from Genomic Rearrangements to Lysogenic Conversion

PubMed Central

Brüssow, Harald; Canchaya, Carlos; Hardt, Wolf-Dietrich

2004-01-01

Comparative genomics demonstrated that the chromosomes from bacteria and their viruses (bacteriophages) are coevolving. This process is most evident for bacterial pathogens where the majority contain prophages or phage remnants integrated into the bacterial DNA. Many prophages from bacterial pathogens encode virulence factors. Two situations can be distinguished: Vibrio cholerae, Shiga toxin-producing Escherichia coli, Corynebacterium diphtheriae, and Clostridium botulinum depend on a specific prophage-encoded toxin for causing a specific disease, whereas Staphylococcus aureus, Streptococcus pyogenes, and Salmonella enterica serovar Typhimurium harbor a multitude of prophages and each phage-encoded virulence or fitness factor makes an incremental contribution to the fitness of the lysogen. These prophages behave like “swarms” of related prophages. Prophage diversification seems to be fueled by the frequent transfer of phage material by recombination with superinfecting phages, resident prophages, or occasional acquisition of other mobile DNA elements or bacterial chromosomal genes. Prophages also contribute to the diversification of the bacterial genome architecture. In many cases, they actually represent a large fraction of the strain-specific DNA sequences. In addition, they can serve as anchoring points for genome inversions. The current review presents the available genomics and biological data on prophages from bacterial pathogens in an evolutionary framework. PMID:15353570

Molecular genetic anatomy of inter- and intraserotype variation in the human bacterial pathogen group A Streptococcus.

PubMed

Beres, Stephen B; Richter, Ellen W; Nagiec, Michal J; Sumby, Paul; Porcella, Stephen F; DeLeo, Frank R; Musser, James M

2006-05-02

In recent years we have studied the relationship between strain genotypes and patient phenotypes in group A Streptococcus (GAS), a model human bacterial pathogen that causes extensive morbidity and mortality worldwide. We have concentrated our efforts on serotype M3 organisms because these strains are common causes of pharyngeal and invasive infections, produce unusually severe invasive infections, and can exhibit epidemic behavior. Our studies have been hindered by the lack of genome-scale phylogenies of multiple GAS strains and whole-genome sequences of multiple serotype M3 strains recovered from individuals with defined clinical phenotypes. To remove some of these impediments, we sequenced to closure the genome of four additional GAS strains and conducted comparative genomic resequencing of 12 contemporary serotype M3 strains representing distinct genotypes and phenotypes. Serotype M3 strains are a single phylogenetic lineage. Strains from asymptomatic throat carriers were significantly less virulent for mice than sterile-site isolates and evolved to a less virulent phenotype by multiple genetic pathways. Strain persistence or extinction between epidemics was strongly associated with presence or absence, respectively, of the prophage encoding streptococcal pyrogenic exotoxin A. A serotype M3 clone significantly underrepresented among necrotizing fasciitis cases has a unique frameshift mutation that truncates MtsR, a transcriptional regulator controlling expression of genes encoding iron-acquisition proteins. Expression microarray analysis of this clone confirmed significant alteration in expression of genes encoding iron metabolism proteins. Our analysis provided unprecedented detail about the molecular anatomy of bacterial strain genotype-patient phenotype relationships.

Use of Antibiotics and Antimicrobial Resistance in Veterinary Medicine as Exemplified by the Swine Pathogen Streptococcus suis.

PubMed

Seitz, Maren; Valentin-Weigand, Peter; Willenborg, Jörg

2016-01-01

Use of antimicrobial agents in veterinary medicine is essential to control infectious diseases, thereby keeping animals healthy and animal products safe for the consumer. On the other hand, development and spread of antimicrobial resistance is of major concern for public health. Streptococcus (S.) suis reflects a typical bacterial pathogen in modern swine production due to its facultative pathogenic nature and wide spread in the pig population. Thus, in the present review we focus on certain current aspects and problems related to antimicrobial use and resistance in S. suis as a paradigm for a bacterial pathogen affecting swine husbandry worldwide. The review includes (i) general aspects of antimicrobial use and resistance in veterinary medicine with emphasis on swine, (ii) genetic resistance mechanisms of S. suis known to contribute to bacterial survival under antibiotic selection pressure, and (iii) possible other factors which may contribute to problems in antimicrobial therapy of S. suis infections, such as bacterial persister cell formation, biofilm production, and co-infections. The latter shows that we hardly understand the complexity of factors affecting the success of antimicrobial treatment of (porcine) infectious diseases and underlines the need for further research in this field.

Transcriptome Remodeling Contributes to Epidemic Disease Caused by the Human Pathogen Streptococcus pyogenes.

PubMed

Beres, Stephen B; Kachroo, Priyanka; Nasser, Waleed; Olsen, Randall J; Zhu, Luchang; Flores, Anthony R; de la Riva, Ivan; Paez-Mayorga, Jesus; Jimenez, Francisco E; Cantu, Concepcion; Vuopio, Jaana; Jalava, Jari; Kristinsson, Karl G; Gottfredsson, Magnus; Corander, Jukka; Fittipaldi, Nahuel; Di Luca, Maria Chiara; Petrelli, Dezemona; Vitali, Luca A; Raiford, Annessa; Jenkins, Leslie; Musser, James M

2016-05-31

For over a century, a fundamental objective in infection biology research has been to understand the molecular processes contributing to the origin and perpetuation of epidemics. Divergent hypotheses have emerged concerning the extent to which environmental events or pathogen evolution dominates in these processes. Remarkably few studies bear on this important issue. Based on population pathogenomic analysis of 1,200 Streptococcus pyogenes type emm89 infection isolates, we report that a series of horizontal gene transfer events produced a new pathogenic genotype with increased ability to cause infection, leading to an epidemic wave of disease on at least two continents. In the aggregate, these and other genetic changes substantially remodeled the transcriptomes of the evolved progeny, causing extensive differential expression of virulence genes and altered pathogen-host interaction, including enhanced immune evasion. Our findings delineate the precise molecular genetic changes that occurred and enhance our understanding of the evolutionary processes that contribute to the emergence and persistence of epidemically successful pathogen clones. The data have significant implications for understanding bacterial epidemics and for translational research efforts to blunt their detrimental effects. The confluence of studies of molecular events underlying pathogen strain emergence, evolutionary genetic processes mediating altered virulence, and epidemics is in its infancy. Although understanding these events is necessary to develop new or improved strategies to protect health, surprisingly few studies have addressed this issue, in particular, at the comprehensive population genomic level. Herein we establish that substantial remodeling of the transcriptome of the human-specific pathogen Streptococcus pyogenes by horizontal gene flow and other evolutionary genetic changes is a central factor in precipitating and perpetuating epidemic disease. The data unambiguously show that

Prevalence and antibiotic resistance profiles of cerebrospinal fluid pathogens in children with acute bacterial meningitis in Yunnan province, China, 2012-2015

PubMed Central

Jiang, Hongchao; Su, Min; Kui, Liyue; Huang, Hailin; Qiu, Lijuan; Li, Li; Ma, Jing; Du, Tingyi; Fan, Mao; Liu, Xiaomei

2017-01-01

Acute bacterial meningitis is still considered one of the most dangerous infectious diseases in children. To investigate the prevalence and antibiotic resistance profiles of cerebrospinal fluid (CSF) pathogens in children with acute bacterial meningitis in Southwest China, CSF samples from 179 meningitis patients (3 days to 12 years old) with positive culture results were collected from 2012 to 2015. Isolated pathogens were identified using the Vitek-32 system. Gram stain results were used to guide subcultures and susceptibility testing. The antimicrobial susceptibility of isolates was determined using the disc diffusion method. Of the isolates, 50.8% were Gram-positive bacteria, and 49.2% were Gram-negative bacteria. The most prevalent pathogens were E. coli (28.5%), Streptococcus pneumoniae (17.8%), Staphylococcus epidermidis (10.0%), Haemophilus influenzae type b (9.5%), and group B streptococcus (7.2%). In young infants aged ≤3 months, E. coli was the organism most frequently isolated from CSF (39/76; 51.3%), followed by group B streptococcus (13/76; 17.1%) and Streptococcus pneumoniae (8/76; 10.5%). However, in young infants aged >3 months, the most frequently isolated organism was Streptococcus pneumoniae (24/103; 23.3%), followed by Staphylococcus epidermidis (18/103; 17.5%) and Haemophilus influenzae type b (16/103; 15.5%). Antimicrobial susceptibility tests indicated that for E. coli isolates, the susceptibility rates to aminoglycosides ranged from 56.8% to 100.0%, among them, amikacin was identified as the most effective against E. coli. As for cephalosporins, the susceptibility rates ranged from 29.4% to 78.4%, and cefoxitin was identified as the most effective cephalosporin. In addition, the susceptibility rates of piperacillin/tazobactam and imipenem against E. coli were 86.3% and 100%. Meanwhile, the susceptibility rates of Streptococcus pneumoniae isolates to penicillin G, erythromycin, chloramphenicol, ceftriaxone and tetracycline were 68.8%, 0

Prevalence and antibiotic resistance profiles of cerebrospinal fluid pathogens in children with acute bacterial meningitis in Yunnan province, China, 2012-2015.

PubMed

Jiang, Hongchao; Su, Min; Kui, Liyue; Huang, Hailin; Qiu, Lijuan; Li, Li; Ma, Jing; Du, Tingyi; Fan, Mao; Sun, Qiangming; Liu, Xiaomei

2017-01-01

Acute bacterial meningitis is still considered one of the most dangerous infectious diseases in children. To investigate the prevalence and antibiotic resistance profiles of cerebrospinal fluid (CSF) pathogens in children with acute bacterial meningitis in Southwest China, CSF samples from 179 meningitis patients (3 days to 12 years old) with positive culture results were collected from 2012 to 2015. Isolated pathogens were identified using the Vitek-32 system. Gram stain results were used to guide subcultures and susceptibility testing. The antimicrobial susceptibility of isolates was determined using the disc diffusion method. Of the isolates, 50.8% were Gram-positive bacteria, and 49.2% were Gram-negative bacteria. The most prevalent pathogens were E. coli (28.5%), Streptococcus pneumoniae (17.8%), Staphylococcus epidermidis (10.0%), Haemophilus influenzae type b (9.5%), and group B streptococcus (7.2%). In young infants aged ≤3 months, E. coli was the organism most frequently isolated from CSF (39/76; 51.3%), followed by group B streptococcus (13/76; 17.1%) and Streptococcus pneumoniae (8/76; 10.5%). However, in young infants aged >3 months, the most frequently isolated organism was Streptococcus pneumoniae (24/103; 23.3%), followed by Staphylococcus epidermidis (18/103; 17.5%) and Haemophilus influenzae type b (16/103; 15.5%). Antimicrobial susceptibility tests indicated that for E. coli isolates, the susceptibility rates to aminoglycosides ranged from 56.8% to 100.0%, among them, amikacin was identified as the most effective against E. coli. As for cephalosporins, the susceptibility rates ranged from 29.4% to 78.4%, and cefoxitin was identified as the most effective cephalosporin. In addition, the susceptibility rates of piperacillin/tazobactam and imipenem against E. coli were 86.3% and 100%. Meanwhile, the susceptibility rates of Streptococcus pneumoniae isolates to penicillin G, erythromycin, chloramphenicol, ceftriaxone and tetracycline were 68.8%, 0

Cationic antimicrobial peptide resistance mechanisms of streptococcal pathogens.

PubMed

LaRock, Christopher N; Nizet, Victor

2015-11-01

Cationic antimicrobial peptides (CAMPs) are critical front line contributors to host defense against invasive bacterial infection. These immune factors have direct killing activity toward microbes, but many pathogens are able to resist their effects. Group A Streptococcus, group B Streptococcus and Streptococcus pneumoniae are among the most common pathogens of humans and display a variety of phenotypic adaptations to resist CAMPs. Common themes of CAMP resistance mechanisms among the pathogenic streptococci are repulsion, sequestration, export, and destruction. Each pathogen has a different array of CAMP-resistant mechanisms, with invasive disease potential reflecting the utilization of several mechanisms that may act in synergy. Here we discuss recent progress in identifying the sources of CAMP resistance in the medically important Streptococcus genus. Further study of these mechanisms can contribute to our understanding of streptococcal pathogenesis, and may provide new therapeutic targets for therapy and disease prevention. This article is part of a Special Issue entitled: Bacterial Resistance to Antimicrobial Peptides. Copyright © 2015 Elsevier B.V. All rights reserved.

Treatment of acute bacterial rhinosinusitis caused by antimicrobial-resistant Streptococcus pneumoniae.

PubMed

Anon, Jack B

2004-08-02

Acute bacterial rhinosinusitis (ABRS) is a secondary bacterial infection of the nose and paranasal sinuses, usually preceded by a viral upper respiratory infection or allergy, with symptoms that have not improved after 10 days or that have worsened after 5 to 7 days. Streptococcus pneumoniae and Haemophilus influenzae are the most common causes of ABRS in adults. Increasing rates of antimicrobial resistance among S. pneumoniae and beta-lactamase production among H. influenzae are formidable challenges to the successful treatment of infections caused by these organisms. To this end, various formulations of amoxicillin-clavulanate have been developed, the most recent of which is pharmacokinetically enhanced and provides a total daily dose of 4,000 mg of amoxicillin and 250 mg of clavulanate. This formulation has been shown to be safe and effective in the treatment of infections caused by penicillin-resistant S. pneumoniae (minimum inhibitory concentration 2 microg/mL); the clavulanate component provides adequate coverage of beta-lactamase-producing pathogens.

Parallel evolution of Streptococcus pneumoniae and Streptococcus mitis to pathogenic and mutualistic lifestyles.

PubMed

Kilian, Mogens; Riley, David R; Jensen, Anders; Brüggemann, Holger; Tettelin, Hervé

2014-07-22

The bacterium Streptococcus pneumoniae is one of the leading causes of fatal infections affecting humans. Intriguingly, phylogenetic analysis shows that the species constitutes one evolutionary lineage in a cluster of the otherwise commensal Streptococcus mitis strains, with which humans live in harmony. In a comparative analysis of 35 genomes, including phylogenetic analyses of all predicted genes, we have shown that the pathogenic pneumococcus has evolved into a master of genomic flexibility while lineages that evolved into the nonpathogenic S. mitis secured harmonious coexistence with their host by stabilizing an approximately 15%-reduced genome devoid of many virulence genes. Our data further provide evidence that interspecies gene transfer between S. pneumoniae and S. mitis occurs in a unidirectional manner, i.e., from S. mitis to S. pneumoniae. Import of genes from S. mitis and other mitis, anginosus, and salivarius group streptococci ensured allelic replacements and antigenic diversification and has been driving the evolution of the remarkable structural diversity of capsular polysaccharides of S. pneumoniae. Our study explains how the unique structural diversity of the pneumococcal capsule emerged and conceivably will continue to increase and reveals a striking example of the fragile border between the commensal and pathogenic lifestyles. While genomic plasticity enabling quick adaptation to environmental stress is a necessity for the pathogenic streptococci, the commensal lifestyle benefits from stability. Importance: One of the leading causes of fatal infections affecting humans, Streptococcus pneumoniae, and the commensal Streptococcus mitis are closely related obligate symbionts associated with hominids. Faced with a shortage of accessible hosts, the two opposing lifestyles evolved in parallel. We have shown that the nonpathogenic S. mitis secured harmonious coexistence with its host by stabilizing a reduced genome devoid of many virulence genes

Toward a Genome-Wide Systems Biology Analysis of Host-Pathogen Interactions in Group A Streptococcus

PubMed Central

Musser, James M.; DeLeo, Frank R.

2005-01-01

Genome-wide analysis of microbial pathogens and molecular pathogenesis processes has become an area of considerable activity in the last 5 years. These studies have been made possible by several advances, including completion of the human genome sequence, publication of genome sequences for many human pathogens, development of microarray technology and high-throughput proteomics, and maturation of bioinformatics. Despite these advances, relatively little effort has been expended in the bacterial pathogenesis arena to develop and use integrated research platforms in a systems biology approach to enhance our understanding of disease processes. This review discusses progress made in exploiting an integrated genome-wide research platform to gain new knowledge about how the human bacterial pathogen group A Streptococcus causes disease. Results of these studies have provided many new avenues for basic pathogenesis research and translational research focused on development of an efficacious human vaccine and novel therapeutics. One goal in summarizing this line of study is to bring exciting new findings to the attention of the investigative pathology community. In addition, we hope the review will stimulate investigators to consider using analogous approaches for analysis of the molecular pathogenesis of other microbes. PMID:16314461

Copper transport and trafficking at the host-bacterial pathogen interface.

PubMed

Fu, Yue; Chang, Feng-Ming James; Giedroc, David P

2014-12-16

CONSPECTUS: The human innate immune system has evolved the means to reduce the bioavailability of first-row late d-block transition metal ions to invading microbial pathogens in a process termed "nutritional immunity". Transition metals from Mn(II) to Zn(II) function as metalloenzyme cofactors in all living cells, and the successful pathogen is capable of mounting an adaptive response to mitigate the effects of host control of transition metal bioavailability. Emerging evidence suggests that Mn, Fe, and Zn are withheld from the pathogen in classically defined nutritional immunity, while Cu is used to kill invading microorganisms. This Account summarizes new molecular-level insights into copper trafficking across cell membranes from studies of a number of important bacterial pathogens and model organisms, including Escherichia coli, Salmonella species, Mycobacterium tuberculosis, and Streptococcus pneumoniae, to illustrate general principles of cellular copper resistance. Recent highlights of copper chemistry at the host-microbial pathogen interface include the first high resolution structures and functional characterization of a Cu(I)-effluxing P1B-ATPase, a new class of bacterial copper chaperone, a fungal Cu-only superoxide dismutase SOD5, and the discovery of a small molecule Cu-bound SOD mimetic. Successful harnessing by the pathogen of host-derived bactericidal Cu to reduce the bacterial load of reactive oxygen species (ROS) is an emerging theme; in addition, recent studies continue to emphasize the importance of short lifetime protein-protein interactions that orchestrate the channeling of Cu(I) from donor to target without dissociation into bulk solution; this, in turn, mitigates the off-pathway effects of Cu(I) toxicity in both the periplasm in Gram negative organisms and in the bacterial cytoplasm. It is unclear as yet, outside of the photosynthetic bacteria, whether Cu(I) is trafficked to other cellular destinations, for example, to cuproenzymes or other

An in silico model for identification of small RNAs in whole bacterial genomes: characterization of antisense RNAs in pathogenic Escherichia coli and Streptococcus agalactiae strains.

PubMed

Pichon, Christophe; du Merle, Laurence; Caliot, Marie Elise; Trieu-Cuot, Patrick; Le Bouguénec, Chantal

2012-04-01

Characterization of small non-coding ribonucleic acids (sRNA) among the large volume of data generated by high-throughput RNA-seq or tiling microarray analyses remains a challenge. Thus, there is still a need for accurate in silico prediction methods to identify sRNAs within a given bacterial species. After years of effort, dedicated software were developed based on comparative genomic analyses or mathematical/statistical models. Although these genomic analyses enabled sRNAs in intergenic regions to be efficiently identified, they all failed to predict antisense sRNA genes (asRNA), i.e. RNA genes located on the DNA strand complementary to that which encodes the protein. The statistical models enabled any genomic region to be analyzed theorically but not efficiently. We present a new model for in silico identification of sRNA and asRNA candidates within an entire bacterial genome. This model was successfully used to analyze the Gram-negative Escherichia coli and Gram-positive Streptococcus agalactiae. In both bacteria, numerous asRNAs are transcribed from the complementary strand of genes located in pathogenicity islands, strongly suggesting that these asRNAs are regulators of the virulence expression. In particular, we characterized an asRNA that acted as an enhancer-like regulator of the type 1 fimbriae production involved in the virulence of extra-intestinal pathogenic E. coli.

An in silico model for identification of small RNAs in whole bacterial genomes: characterization of antisense RNAs in pathogenic Escherichia coli and Streptococcus agalactiae strains

PubMed Central

Pichon, Christophe; du Merle, Laurence; Caliot, Marie Elise; Trieu-Cuot, Patrick; Le Bouguénec, Chantal

2012-01-01

Characterization of small non-coding ribonucleic acids (sRNA) among the large volume of data generated by high-throughput RNA-seq or tiling microarray analyses remains a challenge. Thus, there is still a need for accurate in silico prediction methods to identify sRNAs within a given bacterial species. After years of effort, dedicated software were developed based on comparative genomic analyses or mathematical/statistical models. Although these genomic analyses enabled sRNAs in intergenic regions to be efficiently identified, they all failed to predict antisense sRNA genes (asRNA), i.e. RNA genes located on the DNA strand complementary to that which encodes the protein. The statistical models enabled any genomic region to be analyzed theorically but not efficiently. We present a new model for in silico identification of sRNA and asRNA candidates within an entire bacterial genome. This model was successfully used to analyze the Gram-negative Escherichia coli and Gram-positive Streptococcus agalactiae. In both bacteria, numerous asRNAs are transcribed from the complementary strand of genes located in pathogenicity islands, strongly suggesting that these asRNAs are regulators of the virulence expression. In particular, we characterized an asRNA that acted as an enhancer-like regulator of the type 1 fimbriae production involved in the virulence of extra-intestinal pathogenic E. coli. PMID:22139924

Detection of Bacterial Meningitis Pathogens by PCR-Mass Spectrometry in Cerebrospinal Fluid.

PubMed

Jing-Zi, Piao; Zheng-Xin, He; Wei-Jun, Chen; Yong-Qiang, Jiang

2018-06-01

Acute bacterial meningitis remains a life-threatening infectious disease with considerable morbidity and mortality. DNA-based detection methods are an urgent requisite for meningitis-causing bacterial pathogens for the prevention of outbreaks and control of infections. We proposed a novel PCR-mass spectrometry (PCR-Mass) assay for the simultaneous detection of four meningitis-causing agents, Neisseria meningitidis, Streptococcus pneumoniae, Haemophilus influenzae, and Mycobacterium tuberculosis in the present study. A total of 138 cerebrospinal fluid (CSF) samples (including 56 CSF culture positive, 44 CSF culture negative, and 38 CSF control) were enrolled and analyzed by PCR/Mass. Results were compared to real-time PCR detection. These four targeting pathogens could be discriminated without cross-reaction by the accurate detection of the corresponding extension products with different masses. The limits of detection were 102 copies/reaction for S. pneumoniae, H. influenzae, and N. meningitidis and 103 for M. tuberculosis. The evaluation of the culture-positive CSF specimens from the meningitis patients provided an overall agreement rate of 85.7% with PCR-Mass and real-time PCR. The PCR-Mass was also able to detect the targeting pathogens from culture-negative CSF specimens from meningitis patients receiving early antibiotic treatment. PCR-Mass could be used for the molecular detection of bacterial meningitis and tuberculosis, especially when early antibiotic treatment has been administered to the suspected patients.

Understanding the bacterial polysaccharide antigenicity of Streptococcus agalactiae versus Streptococcus pneumoniae.

PubMed

Kadirvelraj, Renuka; Gonzalez-Outeiriño, Jorge; Foley, B Lachele; Beckham, Meredith L; Jennings, Harold J; Foote, Simon; Ford, Michael G; Woods, Robert J

2006-05-23

Bacterial surface capsular polysaccharides (CPS) that are similar in carbohydrate sequence may differ markedly in immunogenicity and antigenicity. The structural origin of these phenomena is poorly understood. Such a case is presented by the Gram-positive bacteria Streptococcus agalactiae (Group B Streptococcus; GBS) type III (GBSIII) and Streptococcus pneumoniae (Pn) type 14 (Pn14), which share closely related CPS sequences. Nevertheless, antibodies (Abs) against GBSIII rarely cross-react with the CPS from Pn14. To establish the origin for the variation in CPS antigenicity, models for the immune complexes of CPS fragments from GBSIII and Pn14, with the variable fragment (Fv) of a GBS-specific mAb (mAb 1B1), are presented. The complexes are generated through a combination of comparative Ab modeling and automated ligand docking, followed by explicitly solvated 10-ns molecular dynamics simulations. The relationship between carbohydrate sequence and antigenicity is further quantified through the computation of interaction energies using the Molecular Mechanics-Generalized Born Surface Area (MM-GBSA) method, augmented by conformational entropy estimates. Despite the electrostatic differences between Pn14 and GBSIII CPS, analysis indicates that entropic penalties are primarily responsible for the loss of affinity of the highly flexible Pn14 CPS for mAb 1B1. The similarity of the solution conformation of the relatively rigid GBSIII CPS with that in the immune complex characterizes the previously undescribed 3D structure of the conformational epitope. The analysis provides a comprehensive interpretation for a large body of biochemical and immunological data related to Ab recognition of bacterial polysaccharides and should be applicable to other Ab-carbohydrate interactions.

Antibacterial screening of traditional herbal plants and standard antibiotics against some human bacterial pathogens.

PubMed

Awan, Uzma Azeem; Andleeb, Saiqa; Kiyani, Ayesha; Zafar, Atiya; Shafique, Irsa; Riaz, Nazia; Azhar, Muhammad Tehseen; Uddin, Hafeez

2013-11-01

Chloroformic and isoamyl alcohol extracts of Cinnnamomum zylanicum, Cuminum cyminum, Curcuma long Linn, Trachyspermum ammi and selected standard antibiotics were investigated for their in vitro antibacterial activity against six human bacterial pathogens. The antibacterial activity was evaluated and based on the zone of inhibition using agar disc diffusion method. The tested bacterial strains were Streptococcus pyogenes, Staphylococcus epidermidis, Klebsiella pneumonia, Staphylococcus aurues, Serratia marcesnces, and Pseudomonas aeruginosa. Ciprofloxacin showed highly significant action against K. pneumonia and S. epidermidis while Ampicillin and Amoxicillin indicated lowest antibacterial activity against tested pathogens. Among the plants chloroform and isoamyl alcohol extracts of C. cyminum, S. aromaticum and C. long Linn had significant effect against P. aeruginosa, S. marcesnces and S. pyogenes. Comparison of antibacterial activity of medicinal herbs and standard antibiotics was also recorded via activity index. Used medicinal plants have various phytochemicals which reasonably justify their use as antibacterial agent.

BACTERIAL WATERBORNE PATHOGENS

EPA Science Inventory

Bacterial pathogens are examples of classical etiological agents of waterborne disease. While these agents no longer serve as major threats to U.S. water supplies, they are still important pathogens in areas with substandard sanitation and poor water treatment facilities. In th...

Production and Properties of Bacteriocin-Like Inhibitory Substances from the Swine Pathogen Streptococcus suis Serotype 2

PubMed Central

Mélançon, D.; Grenier, D.

2003-01-01

Streptococcus suis serotype 2 is a major pathogen found in the upper respiratory tract of swine. In this study, isolates of this bacterial species were tested for the production of bacteriocin-like inhibitory substances (BLIS). Of the 38 strains tested, four inhibited the growth of other S. suis isolates according to a deferred-antagonism plate assay. Interestingly, three of the strains were originally isolated from healthy carrier pigs and were considered nonvirulent. Three isolates (94-623, 90-1330, and AAH4) that produced BLIS in liquid broth were selected for further characterization. None of the inhibitory activities was related to the production of either organic acids or hydrogen peroxide. The BLIS produced by these strains were heat stable and proteinase K, pronase, and elastase sensitive but were trypsin and chymotrypsin resistant. They were stable at pH 2 and 12 and had molecular masses in the range of 14 to 30 kDa. Maximum production was observed during the mid-log phase. Following a curing procedure with novobiocin, only 90-1330 lost the ability to produce BLIS, suggesting that the BLIS might be plasmid encoded. Analysis of the inhibitory spectra revealed that the BLIS-producing strains also inhibited the growth of Actinobacillus minor, Actinobacillus porcinus, Enterococcus durans, Micrococcus luteus, Streptococcus agalactiae, Streptococcus dysgalactiae subsp. dysgalactiae, Streptococcus equi subsp. zooepidemicus, and S. dysgalactiae subsp. equisimilis. This study reports for the first time the ability of the swine pathogen S. suis serotype 2 to produce BLIS with the characteristics of classic bacteriocins. Further studies are required to investigate the possibility of using bacteriocin-producing strains to prevent swine infections caused by virulent strains of S. suis serotype 2. PMID:12902232

Neutrophil evasion strategies by Streptococcus pneumoniae and Staphylococcus aureus.

PubMed

Lewis, Megan L; Surewaard, Bas G J

2018-03-01

Humans are well equipped to defend themselves against bacteria. The innate immune system employs diverse mechanisms to recognize, control and initiate a response that can destroy millions of different microbes. Microbes that evade the sophisticated innate immune system are able to escape detection and could become pathogens. The pathogens Streptococcus pneumoniae and Staphylococcus aureus are particularly successful due to the development of a wide variety of virulence strategies for bacterial pathogenesis and they invest significant efforts towards mechanisms that allow for neutrophil evasion. Neutrophils are a primary cellular defense and can rapidly kill invading microbes, which is an indispensable function for maintaining host health. This review compares the key features of Streptococcus pneumoniae and Staphylococcus aureus in epidemiology, with a specific focus on virulence mechanisms utilized to evade neutrophils in bacterial pathogenesis. It is important to understand the complex interactions between pathogenic bacteria and neutrophils so that we can disrupt the ability of pathogens to cause disease.

Genome-wide essential gene identification in Streptococcus sanguinis

PubMed Central

Xu, Ping; Ge, Xiuchun; Chen, Lei; Wang, Xiaojing; Dou, Yuetan; Xu, Jerry Z.; Patel, Jenishkumar R.; Stone, Victoria; Trinh, My; Evans, Karra; Kitten, Todd; Bonchev, Danail; Buck, Gregory A.

2011-01-01

A clear perception of gene essentiality in bacterial pathogens is pivotal for identifying drug targets to combat emergence of new pathogens and antibiotic-resistant bacteria, for synthetic biology, and for understanding the origins of life. We have constructed a comprehensive set of deletion mutants and systematically identified a clearly defined set of essential genes for Streptococcus sanguinis. Our results were confirmed by growing S. sanguinis in minimal medium and by double-knockout of paralogous or isozyme genes. Careful examination revealed that these essential genes were associated with only three basic categories of biological functions: maintenance of the cell envelope, energy production, and processing of genetic information. Our finding was subsequently validated in two other pathogenic streptococcal species, Streptococcus pneumoniae and Streptococcus mutans and in two other gram-positive pathogens, Bacillus subtilis and Staphylococcus aureus. Our analysis has thus led to a simplified model that permits reliable prediction of gene essentiality. PMID:22355642

Prevalence of Bovine Mastitis Pathogens in Bulk Tank Milk in China

PubMed Central

Wang, Ya Jing; Qin, Yun; Guix Vallverdú, Roger; Maldonado García, Jaime; Sun, Wei; Li, Shengli; Cao, Zhijun

2016-01-01

The objectives of this study were to estimate the herd prevalence of major mastitis pathogens in bulk tank milk (BTM) in China dairy herds, to determine the relationship between the presence of mastitis pathogens and bulk tank milk somatic cell counts (BTSCC), and to investigate the impact of different dairy cattle farming modes and region on bacterial species. BTM samples collected from 894 dairy herds in China were examined for the presence of mastitis pathogens. The Flinders Technology Associates (FTA) cards were used for BTM sample collection, storage, and transportation and bacterial DNA amplification by real-time PCR. Among contagious pathogens, Staphylococcus aureus, Streptococcus agalactiae, and Streptococcus dysgalactiae were detected in 50.1, 92.2, and 72.3% of the 894 BTM samples, respectively. Among environmental pathogens, E. coli, Streptococcus uberis, Enterococcus spp., Klebsiella spp., Serratia marcescens, Corynebacterium bovis, and Arcanobacterium pyogenes were detected in 28.6, 8.9, 35.7, 20.0, 1.3, 17.0, and 67.2% of the BTM samples, respectively. Staphylococcal β-lactamase gene was detected in 61.7% of the BTM samples. The presence of Staphylococcus aureus and Arcanobacterium pyogenes were significantly associated with high BTSCC, respectively. Significant differences were found in presence of Staphylococcus aureus, Streptococcus agalactiae, and Streptococcus dysgalactiae in BTM sampled from the small household farms, dairy-farming communities, and large-scaled dairy farms. There were significant differences in the presence of Streptococcus agalactiae, Streptococcus dysgalactiae, Arcanobacterium pyogenes, staphylococcal β-lactamase gene, Staphylococcus spp., Klebsiella spp., Enterococcus spp., and Streptococcus uberis in BTM among Inner Mongolia, Heilongjiang, and Hebei province. In conclusion, contagious mammary pathogens are predominated among pathogens in BTM samples in China. PMID:27187065

RNA-mediated regulation in Gram-positive pathogens: an overview punctuated with examples from the group A Streptococcus

PubMed Central

Miller, Eric W.; Cao, Tram N.; Pflughoeft, Kathryn J.; Sumby, Paul

2014-01-01

RNA-based mechanisms of regulation represent a ubiquitous class of regulators that are associated with diverse processes including nutrient sensing, stress response, modulation of horizontal gene transfer, and virulence factor expression. While better studied in Gram-negative bacteria, the literature is replete with examples of the importance of RNA-mediated regulatory mechanisms to the virulence and fitness of Gram-positives. Regulatory RNAs are classified as cis-acting, e.g. riboswitches, which modulate the transcription, translation, or stability of co-transcribed RNA, or trans-acting, e.g. small regulatory RNAs, which target separate mRNAs or proteins. The group A Streptococcus (GAS, Streptococcus pyogenes) is a Gram-positive bacterial pathogen from which several regulatory RNA mechanisms have been characterized. The study of RNA-mediated regulation in GAS has uncovered novel concepts with respect to how small regulatory RNAs may positively regulate target mRNA stability, and to how CRISPR RNAs are processed from longer precursors. This review provides an overview of RNA-mediated regulation in Gram-positive bacteria, and is highlighted with specific examples from GAS research. The key roles that these systems play in regulating bacterial virulence are discussed and future perspectives outlined. PMID:25091277

Streptococcus suis infection

PubMed Central

Feng, Youjun; Zhang, Huimin; Wu, Zuowei; Wang, Shihua; Cao, Min; Hu, Dan; Wang, Changjun

2014-01-01

Streptococcus suis (S. suis) is a family of pathogenic gram-positive bacterial strains that represents a primary health problem in the swine industry worldwide. S. suis is also an emerging zoonotic pathogen that causes severe human infections clinically featuring with varied diseases/syndromes (such as meningitis, septicemia, and arthritis). Over the past few decades, continued efforts have made significant progress toward better understanding this zoonotic infectious entity, contributing in part to the elucidation of the molecular mechanism underlying its high pathogenicity. This review is aimed at presenting an updated overview of this pathogen from the perspective of molecular epidemiology, clinical diagnosis and typing, virulence mechanism, and protective antigens contributing to its zoonosis. PMID:24667807

Streptococcus agalactiae infection in Nile tilapia (Oreochromis niloticus) and its transmission potential to cohabitated sheepshead minnows (Cyprinodon variegatus)

USDA-ARS?s Scientific Manuscript database

Streptococcus agalactiae has emerged as an economically important bacterial pathogen affecting global aquaculture. Worldwide aquaculture losses due to S. agalactiae are estimated around U.S. $1 billion, annually. Streptococcus agalactiae also known as a Lancefield Group B Streptococcus (GBS) is a Gr...

Molecular serotyping, virulence gene profiling and pathogenicity of Streptococcus agalactiae isolated from tilapia farms in Thailand by multiplex PCR.

PubMed

Kannika, K; Pisuttharachai, D; Srisapoome, P; Wongtavatchai, J; Kondo, H; Hirono, I; Unajak, S; Areechon, N

2017-06-01

This study aimed to biotype Streptococcus agalactiae isolated from tilapia farms in Thailand based on molecular biotyping methods and to determine the correlation between the serotype and virulence of bacteria. In addition to a biotyping (serotyping) technique based on multiplex PCR of cps genes, in this study, we developed multiplex PCR typing of Group B streptococcus (GBS) virulence genes to examine three clusters of virulence genes and their correlation with the pathogenicity of S. agalactiae. The epidemiology of S. agalactiae in Thailand was analysed to provide bacterial genetic information towards a future rational vaccine strategy for tilapia culture systems. Streptococcus agalactiae were isolated from diseased tilapia from different areas of Thailand. A total of 124 S. agalactiae isolates were identified by phenotypic analysis and confirmed by 16S rRNA PCR. Bacterial genotyping was conducted based on (i) molecular serotyping of the capsular polysaccharide (cps) gene cluster and (ii) virulence gene profiling using multiplex PCR analysis of 14 virulence genes (lmb, scpB, pavA, cspA, spb1, cyl, bca, rib, fbsA, fbsB, cfb, hylB, bac and pbp1A/ponA). Only serotypes Ia and III were found in this study; serotype Ia lacks the lmb, scpB and spb1 genes, whereas serotype III lacks only the bac gene. Virulence tests in juvenile Nile tilapia demonstrated a correlation between the pathogenicity of the bacteria and their virulence gene profile, with serotype III showing higher virulence than serotype Ia. Epidemiological analysis showed an almost equal distribution in all regions of Thailand, except serotype III was found predominantly in the southern areas. Only two serotypes of S. agalactiae were isolated from diseased tilapia in Thailand. Serotype Ia showed fewer virulence genes and lower virulence than serotype III. Both serotypes showed a similar distribution throughout Thailand. We identified two major serotypes of S. agalactiae isolates associated with the outbreak in

Simultaneous Detection of 13 Key Bacterial Respiratory Pathogens by Combination of Multiplex PCR and Capillary Electrophoresis.

PubMed

Jiang, Lu Xi; Ren, Hong Yu; Zhou, Hai Jian; Zhao, Si Hong; Hou, Bo Yan; Yan, Jian Ping; Qin, Tian; Chen, Yu

2017-08-01

Lower respiratory tract infections continue to pose a significant threat to human health. It is important to accurately and rapidly detect respiratory bacteria. To compensate for the limits of current respiratory bacteria detection methods, we developed a combination of multiplex polymerase chain reaction (PCR) and capillary electrophoresis (MPCE) assay to detect thirteen bacterial pathogens responsible for lower respiratory tract infections, including Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis, Pseudomonas aeruginosa, Klebsiella pneumoniae, Escherichia coli, Staphylococcus aureus, Mycoplasma pneumoniae, Legionella spp., Bordetella pertussis, Mycobacterium tuberculosis complex, Corynebacterium diphtheriae, and Streptococcus pyogenes. Three multiplex PCR reactions were built, and the products were analyzed by capillary electrophoresis using the high-throughput DNA analyzer. The specificity of the MPCE assay was examined and the detection limit was evaluated using DNA samples from each bacterial strain and the simulative samples of each strain. This assay was further evaluated using 152 clinical specimens and compared with real-time PCR reactions. For this assay, three nested-multiplex-PCRs were used to detect these clinical specimens. The detection limits of the MPCE assay for the 13 pathogens were very low and ranged from 10-7 to 10-2 ng/μL. Furthermore, analysis of the 152 clinical specimens yielded a specificity ranging from 96.5%-100.0%, and a sensitivity of 100.0% for the 13 pathogens. This study revealed that the MPCE assay is a rapid, reliable, and high-throughput method with high specificity and sensitivity. This assay has great potential in the molecular epidemiological survey of respiratory pathogens. Copyright © 2017 The Editorial Board of Biomedical and Environmental Sciences. Published by China CDC. All rights reserved.

Streptococcus sanguinis biofilm formation & interaction with oral pathogens.

PubMed

Zhu, Bin; Macleod, Lorna C; Kitten, Todd; Xu, Ping

2018-06-08

Caries and periodontitis are the two most common human dental diseases and are caused by dysbiosis of oral flora. Although commensal microorganisms have been demonstrated to protect against pathogens and promote oral health, most previous studies have addressed pathogenesis rather than commensalism. Streptococcus sanguinis is a commensal bacterium that is abundant in the oral biofilm and whose presence is correlated with health. Here, we focus on the mechanism of biofilm formation in S. sanguinis and the interaction of S. sanguinis with caries- and periodontitis-associated pathogens. In addition, since S. sanguinis is well known as a cause of infective endocarditis, we discuss the relationship between S. sanguinis biofilm formation and its pathogenicity in endocarditis.

Analysis of bacterial metagenomes from the Southwestern Gulf of Mexico for pathogens detection.

PubMed

Escobedo-Hinojosa, Wendy; Pardo-López, Liliana

2017-07-31

Little is known about the diversity of bacteria in the Southwestern Gulf of Mexico. The aim of the study illustrated in this perspective was to search for the presence of bacterial pathogens in this ecosystem, using metagenomic data recently generated by the Mexican research group known as the Gulf of Mexico Research Consortium. Several genera of bacteria annotated as pathogens were detected in water and sediment marine samples. As expected, native and ubiquitous pathogenic bacteria genera such as Burkolderia, Halomonas, Pseudomonas, Shewanella and Vibrio were highly represented. Surprisingly, non-native genera of public health concern were also detected, including Borrelia, Ehrlichia, Leptospira, Mycobacterium, Mycoplasma, Salmonella, Staphylococcus, Streptococcus and Treponema. While there are no previous metagenomics studies of this environment, the potential influences of natural, anthropogenic and ecological factors on the diversity of putative pathogenic bacteria found in it are reviewed. The taxonomic annotation herein reported provides a starting point for an improved understanding of bacterial biodiversity in the Southwestern Gulf of Mexico. It also represents a useful tool in public health as it may help identify infectious diseases associated with exposure to marine water and ingestion of fish or shellfish, and thus may be useful in predicting and preventing waterborne disease outbreaks. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Patterns of isolation of common gram positive bacterial pathogens and their susceptibilities to antimicrobial agents in Jimma Hospital.

PubMed

Gebreselassie, Solomon

2002-04-01

Gram positive bacteria are frequently emerging as antibiotic resistant pathogens, causing serious infections than ever before in the ill and debilitated patients. The pattern of isolation and the antimicrobial susceptibilities of common Gram positive cocci including Staphylococcus aureus, coagulase negative staphylococcus (CoNS), Streptococcus pyogenes, Enterococcus species and Streptococcus pneumoniae was investigated between January 1997 and June 2000 in Jimma Hospital. Of the 500 specimens collected from children and adults, 116 (23.2%) consisted of one or more of the above organisms. The following strains: Staphylococcus aureus, 47 (40.5%), CoNS, 36 (31.0%), Streptococcus pneumoniae, 26 (22.4%) Streptococcus pyogenes, 5 (4.3%) and Streptococcus faecalis, 2(1.7%) were isolated from different specimens including pus, sputum, urine, stool, blood and oro/nasopharyngeal swabs of patients. The in vitro activities of 14 different antibiotics including penicillin G, ampicillin, cloxacillin, cephalothin, gentamicin, kanamycin, tetracycline, chloramphenicol, erythromycin, trimethoprim-sulfamethoxazole, streptomycin, methicillin, vancomycin and clindamycin was determined against the clinical bacterial isolates. The antimicrobial activities were evaluated by agar diffusion technique using Mueller-Hinton agar according to NCCLS recommendations. The majority of the pathogens, 59(50.9%) were recovered from upper respiratory tract infections and 17 (14.6%) from the lower respiratory tract. The resistance patterns of S. aureus, CoNS, S. pneumoniae and enterococci to penicillin was 91.5%, 94.4%, 7.7% and 100% respectively. Penicillin, ampicillin and cloxacillin showed low effects (< 60%) on both S. aureus and CoNS. Multi-drug resistance was observed in all the gram-positive isolates, especially higher in staphylococcus species. All isolates of S. aureus (100%) were susceptible to vancomycin, clindamycin and gentamicin. In order to reduce morbidity and mortality due to antibiotic

Microbiology: Detection of Bacterial Pathogens and Their Occurrence.

ERIC Educational Resources Information Center

Reasoner, Donald J.

1978-01-01

Presents a literature review of bacterial pathogens that are related to water pollution, covering publications from 1976-77. This review includes: (1) bacterial pathogens in animals; and (2) detection and identification of waterborne bacterial pathogens. A list of 129 references is also presented. (HM)

Cationic Antimicrobial Peptide Resistance Mechanisms of Streptococcal Pathogens

PubMed Central

LaRock, Christopher N.; Nizet, Victor

2015-01-01

Cationic antimicrobial peptides (CAMPs) are critical front line contributors to host defense against invasive bacterial infection. These immune factors have direct killing activity toward microbes, but many pathogens are able to resist their effects. Group A Streptococcus, group B Streptococcus and Streptococcus pneumoniae are among the most common pathogens of humans and display a variety of phenotypic adaptations to resist CAMPs. Common themes of CAMP resistance mechanisms among the pathogenic streptococci are repulsion, sequestration, export, and destruction. Each pathogen has a different array of CAMP-resistant mechanisms, with invasive disease potential reflecting the utilization of several mechanisms that may act in synergy. Here we discuss recent progress in identifying the sources of CAMP resistance in the medically important Streptococcus genus. Further study of these mechanisms can contribute to our understanding of streptococcal pathogenesis, and may provide new therapeutic targets for therapy and disease prevention. PMID:25701232

Endocarditis in adults with bacterial meningitis.

PubMed

Lucas, Marjolein J; Brouwer, Matthijs C; van der Ende, Arie; van de Beek, Diederik

2013-05-21

Endocarditis may precede or complicate bacterial meningitis, but the incidence and impact of endocarditis in bacterial meningitis are unknown. We assessed the incidence and clinical characteristics of patients with meningitis and endocarditis from a nationwide cohort study of adults with community-acquired bacterial meningitis in the Netherlands from 2006 to 2012. Endocarditis was identified in 24 of 1025 episodes (2%) of bacterial meningitis. Cultures yielded Streptococcus pneumoniae in 13 patients, Staphylococcus aureus in 8 patients, and Streptococcus agalactiae, Streptococcus pyogenes, and Streptococcus salivarius in 1 patient each. Clues leading to the diagnosis of endocarditis were cardiac murmurs, persistent or recurrent fever, a history of heart valve disease, and S aureus as the causative pathogen of bacterial meningitis. Treatment consisted of prolonged antibiotic therapy in all patients and surgical valve replacement in 10 patients (42%). Two patients were treated with oral anticoagulants, and both developed life-threatening intracerebral hemorrhage. Systemic (70%) and neurological (54%) complications occurred frequently, leading to a high proportion of patients with unfavorable outcome (63%). Seven of 24 patients (29%) with meningitis and endocarditis died. Endocarditis is an uncommon coexisting condition in bacterial meningitis but is associated with a high rate of unfavorable outcome.

Detection of respiratory bacterial pathogens causing atypical pneumonia by multiplex Lightmix® RT-PCR.

PubMed

Wagner, Karoline; Springer, Burkard; Imkamp, Frank; Opota, Onya; Greub, Gilbert; Keller, Peter M

2018-04-01

Pneumonia is a severe infectious disease. In addition to common viruses and bacterial pathogens (e.g. Streptococcus pneumoniae), fastidious respiratory pathogens like Chlamydia pneumoniae, Mycoplasma pneumoniae and Legionella spp. can cause severe atypical pneumonia. They do not respond to penicillin derivatives, which may cause failure of antibiotic empirical therapy. The same applies for infections with B. pertussis and B. parapertussis, the cause of pertussis disease, that may present atypically and need to be treated with macrolides. Moreover, these fastidious bacteria are difficult to identify by culture or serology, and therefore often remain undetected. Thus, rapid and accurate identification of bacterial pathogens causing atypical pneumonia is crucial. We performed a retrospective method evaluation study to evaluate the diagnostic performance of the new, commercially available Lightmix ® multiplex RT-PCR assay that detects these fastidious bacterial pathogens causing atypical pneumonia. In this retrospective study, 368 clinical respiratory specimens, obtained from patients suffering from atypical pneumonia that have been tested negative for the presence of common agents of pneumonia by culture and viral PCR, were investigated. These clinical specimens have been previously characterized by singleplex RT-PCR assays in our diagnostic laboratory and were used to evaluate the diagnostic performance of the respiratory multiplex Lightmix ® RT-PCR. The multiplex RT-PCR displayed a limit of detection between 5 and 10 DNA copies for different in-panel organisms and showed identical performance characteristics with respect to specificity and sensitivity as in-house singleplex RT-PCRs for pathogen detection. The Lightmix ® multiplex RT-PCR assay represents a low-cost, time-saving and accurate diagnostic tool with high throughput potential. The time-to-result using an automated DNA extraction device for respiratory specimens followed by multiplex RT-PCR detection was

Pathogenic flora composition and overview of the trends used for bacterial pathogenicity identifications.

PubMed

Orji, Frank Anayo; Ugbogu, Ositadinma Chinyere; Ugbogu, Eziuche Amadike; Barbabosa-Pliego, Alberto; Monroy, Jose Cedillo; Elghandour, Mona M M Y; Salem, Abdelfattah Z M

2018-05-05

Over 250 species of resident flora in the class of bacteria are known to be associated with humans. These conventional flora compositions is often determined by factors which may not be limited to genetics, age, sex, stress and nutrition of humans. Man is constantly in contact with bacteria through media such as air, water, soil and food. This paper reviews the concept of bacterial pathogenesis from the sequential point of colonization to tissue injury. The paper in addition to examination of the factors which enhance virulence in bacterial pathogens also x-rayed the concept of pathogenicity islands and the next generation approaches or rather current trends/methods used in the bacterial pathogenicity investigations. In terms of pathogenicity which of course is the capacity to cause disease in animals, requires that the attacking bacterial strain is virulent, and has ability to bypass the host immune defensive mechanisms. In order to achieve or exhibit pathogenicity, the virulence factors required by microorganisms include capsule, pigments, enzymes, iron acquisition through siderophores. Bacterial Pathogenicity Islands as a distinct concept in bacterial pathogenesis are just loci on the chromosome or extra chromosomal units which are acquired by horizontal gene transfer within pathogens in a microbial community or biofilm. In the area of laboratory investigations, bacterial pathogenesis was initially carried out using culture dependent approaches, which can only detect about 1% of human and veterinary-important pathogens. However, in the recent paradigms shift, the use of proteomics, metagenomics, phylogenetic tree analyses, spooligotyping, and finger printing etc. have made it possible that 100% of the bacterial pathogens in nature can be extensively studied. Copyright © 2018 Elsevier Ltd. All rights reserved.

Severe invasive streptococcal infection by Streptococcus pyogenes and Streptococcus dysgalactiae subsp. equisimilis.

PubMed

Watanabe, Shinya; Takemoto, Norihiko; Ogura, Kohei; Miyoshi-Akiyama, Tohru

2016-01-01

Streptococcus pyogenes, a group A Streptococcus (GAS), has been recognized as the causative pathogen in patients with severe invasive streptococcal infection with or without necrotizing fasciitis. In recent epidemiological studies, Streptococcus dysgalactiae subsp. equisimilis (SDSE) has been isolated from severe invasive streptococcal infection. Complete genome sequence showed that SDSE is the closest bacterial species to GAS, with approximately 70% of genome coverage. SDSE, however, lacks several key virulence factors present in GAS, such as SPE-B, the hyaluronan synthesis operon and active superantigen against human immune cells. A key event in the ability of GAS to cause severe invasive streptococcal infection was shown to be the acquisition of novel genetic traits such as phages. Strikingly, however, during severe invasive infection, GAS destroys its own covRS two-component system, which negatively regulates many virulence factor genes, resulting in a hyper-virulent phenotype. In contrast, this phenomenon has not been observed in SDSE. The present review describes the epidemiology of severe invasive streptococcal infection and the detailed pathogenic mechanisms of GAS and SDSE, emphasizing findings from their genome sequences and analyses of gene expression. © 2015 The Societies and John Wiley & Sons Australia, Ltd.

Relationship between lactobacilli and opportunistic bacterial pathogens associated with vaginitis.

PubMed

Razzak, Mohammad Sabri A; Al-Charrakh, Alaa H; Al-Greitty, Bara Hamid

2011-04-01

Vaginitis, is an infectious inflammation of the vaginal mucosa, which sometimes involves the vulva. The balance of the vaginal flora is maintained by the Lactobacilli and its protective and probiotic role in treating and preventing vaginal infection by producing antagonizing compounds which are regarded as safe for humans. The aim of this study was to evaluate the protective role of Lactobacilli against common bacterial opportunistic pathogens in vaginitis and study the effects of some antibiotics on Lactobacilli isolates. In this study (110) vaginal swabs were obtained from women suffering from vaginitis who admitted to Babylon Hospital of Maternity and Paediatrics in Babylon province, Iraq. The study involved the role of intrauterine device among married women with vaginitis and also involved isolation of opportunistic bacterial isolates among pregnant and non pregnant women. This study also involved studying probiotic role of Lactobacilli by production of some defense factors like hydrogen peroxide, bacteriocin, and lactic acid. Results revealed that a total of 130 bacterial isolates were obtained. Intrauterine device was a predisposing factor for vaginitis. The most common opportunistic bacterial isolates were Staphylococcus aureus, Escherichia coli, Streptococcus agalactiae, and Klebsiella pneumoniae. All Lactobacilli were hydrogen peroxide producers while some isolates were bacteriocin producers that inhibited some of opportunistic pathogens (S. aureus, E. coli). Lactobacilli were sensitive to erythromycin while 93.3% of them were resistant to ciprofloxacin and (40%, 53.3%) of them were resistant to amoxicillin and gentamycin respectively. Results revealed that there was an inverse relationship between Lactobacilli presence and organisms causing vaginitis. This may be attributed to the production of defense factors by Lactobacilli. The types of antibiotics used to treat vaginitis must be very selective in order not to kill the beneficial bacteria

Relationship between lactobacilli and opportunistic bacterial pathogens associated with vaginitis

PubMed Central

Razzak, Mohammad Sabri A.; Al-Charrakh, Alaa H.; AL-Greitty, Bara Hamid

2011-01-01

Background: Vaginitis, is an infectious inflammation of the vaginal mucosa, which sometimes involves the vulva. The balance of the vaginal flora is maintained by the Lactobacilli and its protective and probiotic role in treating and preventing vaginal infection by producing antagonizing compounds which are regarded as safe for humans. Aim: The aim of this study was to evaluate the protective role of Lactobacilli against common bacterial opportunistic pathogens in vaginitis and study the effects of some antibiotics on Lactobacilli isolates. Materials and Methods: In this study (110) vaginal swabs were obtained from women suffering from vaginitis who admitted to Babylon Hospital of Maternity and Paediatrics in Babylon province, Iraq. The study involved the role of intrauterine device among married women with vaginitis and also involved isolation of opportunistic bacterial isolates among pregnant and non pregnant women. This study also involved studying probiotic role of Lactobacilli by production of some defense factors like hydrogen peroxide, bacteriocin, and lactic acid. Results: Results revealed that a total of 130 bacterial isolates were obtained. Intrauterine device was a predisposing factor for vaginitis. The most common opportunistic bacterial isolates were Staphylococcus aureus, Escherichia coli, Streptococcus agalactiae, and Klebsiella pneumoniae. All Lactobacilli were hydrogen peroxide producers while some isolates were bacteriocin producers that inhibited some of opportunistic pathogens (S. aureus, E. coli). Lactobacilli were sensitive to erythromycin while 93.3% of them were resistant to ciprofloxacin and (40%, 53.3%) of them were resistant to amoxicillin and gentamycin respectively. Results revealed that there was an inverse relationship between Lactobacilli presence and organisms causing vaginitis. This may be attributed to the production of defense factors by Lactobacilli. Conclusion: The types of antibiotics used to treat vaginitis must be very

Bacterial reproductive pathogens of cats and dogs.

PubMed

Graham, Elizabeth M; Taylor, David J

2012-05-01

With the notable exception of Brucella canis, exogenous bacterial pathogens are uncommon causes of reproductive disease in cats and dogs. Most bacterial reproductive infections are endogenous, and predisposing factors for infection are important. This article reviews the etiology, pathogenesis, clinical presentation, diagnosis, treatment, and public health significance of bacterial reproductive pathogens in cats and dogs.

Superoxide anions produced by Streptococcus pyogenes group A-stimulated keratinocytes are responsible for cellular necrosis and bacterial growth inhibition.

PubMed

Regnier, Elodie; Grange, Philippe A; Ollagnier, Guillaume; Crickx, Etienne; Elie, Laetitia; Chouzenoux, Sandrine; Weill, Bernard; Plainvert, Céline; Poyart, Claire; Batteux, Frédéric; Dupin, Nicolas

2016-02-01

Gram-positive Streptococcus pyogenes (group A Streptococcus or GAS) is a major skin pathogen and interacts with keratinocytes in cutaneous tissues. GAS can cause diverse suppurative and inflammatory infections, such as cellulitis, a common acute bacterial dermo-hypodermitis with a high morbidity. Bacterial isolation yields from the lesions are low despite the strong local inflammation observed, raising numerous questions about the pathogenesis of the infection. Using an in vitro model of GAS-infected keratinocytes, we show that the major ROS produced is the superoxide anion ([Formula: see text]), and that its production is time- and dose-dependent. Using specific modulators of ROS production, we show that [Formula: see text] is mainly synthesized by the cytoplasmic NADPH oxidase. Superoxide anion production leads to keratinocyte necrosis but incomplete inhibition of GAS growth, suggesting that GAS may be partially resistant to the oxidative burst. In conclusion, GAS-stimulated keratinocytes are able to develop an innate immune response based on the production of ROS. This local immune response limits GAS development and induces keratinocyte cell death, resulting in the skin lesions observed in patients with cellulitis. © The Author(s) 2015.

High-level fluorescence labeling of gram-positive pathogens.

PubMed

Aymanns, Simone; Mauerer, Stefanie; van Zandbergen, Ger; Wolz, Christiane; Spellerberg, Barbara

2011-01-01

Fluorescence labeling of bacterial pathogens has a broad range of interesting applications including the observation of living bacteria within host cells. We constructed a novel vector based on the E. coli streptococcal shuttle plasmid pAT28 that can propagate in numerous bacterial species from different genera. The plasmid harbors a promoterless copy of the green fluorescent variant gene egfp under the control of the CAMP-factor gene (cfb) promoter of Streptococcus agalactiae and was designated pBSU101. Upon transfer of the plasmid into streptococci, the bacteria show a distinct and easily detectable fluorescence using a standard fluorescence microscope and quantification by FACS-analysis demonstrated values that were 10-50 times increased over the respective controls. To assess the suitability of the construct for high efficiency fluorescence labeling in different gram-positive pathogens, numerous species were transformed. We successfully labeled Streptococcus pyogenes, Streptococcus agalactiae, Streptococcus dysgalactiae subsp. equisimilis, Enterococcus faecalis, Enterococcus faecium, Streptococcus mutans, Streptococcus anginosus and Staphylococcus aureus strains utilizing the EGFP reporter plasmid pBSU101. In all of these species the presence of the cfb promoter construct resulted in high-level EGFP expression that could be further increased by growing the streptococcal and enterococcal cultures under high oxygen conditions through continuous aeration.

High-Level Fluorescence Labeling of Gram-Positive Pathogens

PubMed Central

Aymanns, Simone; Mauerer, Stefanie; van Zandbergen, Ger; Wolz, Christiane; Spellerberg, Barbara

2011-01-01

Fluorescence labeling of bacterial pathogens has a broad range of interesting applications including the observation of living bacteria within host cells. We constructed a novel vector based on the E. coli streptococcal shuttle plasmid pAT28 that can propagate in numerous bacterial species from different genera. The plasmid harbors a promoterless copy of the green fluorescent variant gene egfp under the control of the CAMP-factor gene (cfb) promoter of Streptococcus agalactiae and was designated pBSU101. Upon transfer of the plasmid into streptococci, the bacteria show a distinct and easily detectable fluorescence using a standard fluorescence microscope and quantification by FACS-analysis demonstrated values that were 10–50 times increased over the respective controls. To assess the suitability of the construct for high efficiency fluorescence labeling in different gram-positive pathogens, numerous species were transformed. We successfully labeled Streptococcus pyogenes, Streptococcus agalactiae, Streptococcus dysgalactiae subsp. equisimilis, Enterococcus faecalis, Enterococcus faecium, Streptococcus mutans, Streptococcus anginosus and Staphylococcus aureus strains utilizing the EGFP reporter plasmid pBSU101. In all of these species the presence of the cfb promoter construct resulted in high-level EGFP expression that could be further increased by growing the streptococcal and enterococcal cultures under high oxygen conditions through continuous aeration. PMID:21731607

Transcriptome landscape of a bacterial pathogen under plant immunity.

PubMed

Nobori, Tatsuya; Velásquez, André C; Wu, Jingni; Kvitko, Brian H; Kremer, James M; Wang, Yiming; He, Sheng Yang; Tsuda, Kenichi

2018-03-27

Plant pathogens can cause serious diseases that impact global agriculture. The plant innate immunity, when fully activated, can halt pathogen growth in plants. Despite extensive studies into the molecular and genetic bases of plant immunity against pathogens, the influence of plant immunity in global pathogen metabolism to restrict pathogen growth is poorly understood. Here, we developed RNA sequencing pipelines for analyzing bacterial transcriptomes in planta and determined high-resolution transcriptome patterns of the foliar bacterial pathogen Pseudomonas syringae in Arabidopsis thaliana with a total of 27 combinations of plant immunity mutants and bacterial strains. Bacterial transcriptomes were analyzed at 6 h post infection to capture early effects of plant immunity on bacterial processes and to avoid secondary effects caused by different bacterial population densities in planta We identified specific "immune-responsive" bacterial genes and processes, including those that are activated in susceptible plants and suppressed by plant immune activation. Expression patterns of immune-responsive bacterial genes at the early time point were tightly linked to later bacterial growth levels in different host genotypes. Moreover, we found that a bacterial iron acquisition pathway is commonly suppressed by multiple plant immune-signaling pathways. Overexpression of a P. syringae sigma factor gene involved in iron regulation and other processes partially countered bacterial growth restriction during the plant immune response triggered by AvrRpt2. Collectively, this study defines the effects of plant immunity on the transcriptome of a bacterial pathogen and sheds light on the enigmatic mechanisms of bacterial growth inhibition during the plant immune response.

[Pathogen distribution and bacterial resistance in children with severe community-acquired pneumonia].

PubMed

Lu, Yun-Yun; Luo, Rong; Fu, Zhou

2017-09-01

To investigate the distribution of pathogens and bacterial resistance in children with severe community-acquired pneumonia (CAP). A total of 522 children with severe CAP who were hospitalized in 2016 were enrolled as study subjects. According to their age, they were divided into infant group (402 infants aged 28 days to 1 year), young children group (73 children aged 1 to 3 years), preschool children group (35 children aged 3 to 6 years), and school-aged children group (12 children aged ≥6 years). According to the onset season, all children were divided into spring group (March to May, 120 children), summer group (June to August, 93 children), autumn group (September to November, 105 children), and winter group (December to February, 204 children). Sputum specimens from the deep airway were collected from all patients. The phoenix-100 automatic bacterial identification system was used for bacterial identification and drug sensitivity test. The direct immunofluorescence assay was used to detect seven common respiratory viruses. The quantitative real-time PCR was used to detect Mycoplasma pneumoniae (MP) and Chlamydia trachomatis (CT). Of all the 522 children with severe CAP, 419 (80.3%) were found to have pathogens, among whom 190 (45.3%) had mixed infection. A total of 681 strains of pathogens were identified, including 371 bacterial strains (54.5%), 259 viral strains (38.0%), 12 fungal strains (1.8%), 15 MP strains (2.2%), and 24 CT strains (3.5%). There were significant differences in the distribution of bacterial, viral, MP, and fungal infections between different age groups (P<0.05). There were significant differences in the incidence rate of viral infection between different season groups (P<0.05), with the highest incidence rate in winter. The drug-resistance rates of Streptococcus pneumoniae to erythromycin, tetracycline, and clindamycin reached above 85%, and the drug-resistance rates of Staphylococcus aureus to penicillin, erythromycin, and clindamycin

Bacterial pneumonia as an influenza complication.

PubMed

Martin-Loeches, Ignacio; van Someren Gréve, Frank; Schultz, Marcus J

2017-04-01

The pathogenesis and impact of coinfection, in particular bacterial coinfection, in influenza are incompletely understood. This review summarizes results from studies on bacterial coinfection in the recent pandemic influenza outbreak. Systemic immune mechanisms play a key role in the development of coinfection based on the complexity of the interaction of the host and the viral and bacterial pathogens. Several studies were performed to determine the point prevalence of bacterial coinfection in influenza. Coinfection in influenza is frequent in critically ill patients with Streptococcus pneumoniae being the most frequent bacterial pathogen and higher rates of potentially resistant pathogens over the years. Bacterial pneumonia is certainly an influenza complication. The recent epidemiology findings have helped to partially resolve the contribution of different pathogens. Immunosuppression is a risk factor for bacterial coinfection in influenza, and the epidemiology of coinfection has changed over the years during the last influenza pandemic, and these recent findings should be taken into account during present outbreaks.

Isolation, pathogenicity and characterization of a novel bacterial pathogen Streptococcus uberis from diseased mandarin fish Siniperca chuatsi.

PubMed

Luo, Xia; Fu, Xiaozhe; Liao, Guoli; Chang, Ouqin; Huang, Zhibin; Li, Ningqiu

2017-06-01

In recent years, mandarin fish had a high mortality rate associated with abnormal swimming, exophthalmia, corneal opacity and eye hemorrhage on a fish farm located at Foshan city, Guangdong province, China. Three isolates of Gram-positive, chain-forming cocci were recovered from moribund fish, and designated as SS131025-1, SS131025-2, and SS131025-3. These isolates were identified as Streptococcus uberis according to their morphologic and physio-biochemical characteristics as well as phylogenetic analysis based on their 16S rRNA and GapC gene sequences. The pathogenicity of S. uberis to mandarin fish was determined by challenge experiments. Results of artificial challenge showed S. uberis infected healthy mandarin fish and lead to death by eyeball injection or immersion route, and the LD 50 of SS131025-1 with eyeball injection was 2.0 × 10 6.42  CFU per fish. Moreover extracellular product (ECP) of the isolated S.uberis induced CPB cell apoptosis and cause death of mandarin fish. In addition, these S. uberis strains could also infect tilapia, but not grass carp and crucian carp, and grew in brain-heart infusion broth with an optimal temperature of 37 °C, pH of 7.0, and salinity of 0%. Antibiotic sensitivity testing indicated that these isolates were susceptible to rifampicin and furazolidone but resistant to 20 kinds of antibiotics. Histopathologically, infection with S. uberis could cause serious pathological changes in brain tissues such as vacuoles in matrix, swollen mitochondria with lysis of cristae and disintegration, and lots of coccus was observed both under electron and light microscope. These results shed some light on the pathogenicity of the isolates and how to prevent and control S. uberis infection in mandarin fish. Copyright © 2017 Elsevier Ltd. All rights reserved.

Chlorhexidine digluconate effects on planktonic growth and biofilm formation in some field isolates of animal bacterial pathogens.

PubMed

Ebrahimi, Azizollah; Hemati, Majid; Habibian Dehkordi, Saeed; Bahadoran, Shahab; Khoshnood, Sheida; Khubani, Shahin; Dokht Faraj, Mahdi; Hakimi Alni, Reza

2014-05-01

To study chlorhexidine digluconate disinfectant effects on planktonic growth and biofilm formation in some bacterial field isolates from animals. The current study investigated chlorhexidine digluconate effects on planktonic growth and biofilm formation in some field isolates of veterinary bacterial pathogens. Forty clinical isolates of Escherichia coli, Salmonella serotypes, Staphylococcus. aureus and Streptococcus agalactiae (10 isolates for each) were examined for chlorhexidine digluconate effects on biofilm formation and planktonic growth using microtiter plates. In all of the examined strains in the presence of chlorhexidine digluconate, biofilm development and planktonic growth were affected at the same concentrations of the disinfectant. Chlorhexidine digluconate inhibited the planktonic growth of different bacterial species at sub-MICs. But they were able to induce biofilm development of the E. coli, Salmonella spp., S. aureus and Str. agalactiae strains. Bacterial resistance against chlorhexidine is increasing. Sub-MIC doses of chlorhexidine digluconate can stimulate the formation of biofilm strains.

Large scale genomic analysis shows no evidence for pathogen adaptation between the blood and cerebrospinal fluid niches during bacterial meningitis

PubMed Central

Lees, John A.; Kremer, Philip H. C.; Manso, Ana S.; Croucher, Nicholas J.; Ferwerda, Bart; Serón, Mercedes Valls; Oggioni, Marco R.; Parkhill, Julian; Brouwer, Matthijs C.; van der Ende, Arie; van de Beek, Diederik

2017-01-01

Recent studies have provided evidence for rapid pathogen genome diversification, some of which could potentially affect the course of disease. We have previously described such variation seen between isolates infecting the blood and cerebrospinal fluid (CSF) of a single patient during a case of bacterial meningitis. Here, we performed whole-genome sequencing of paired isolates from the blood and CSF of 869 meningitis patients to determine whether such variation frequently occurs between these two niches in cases of bacterial meningitis. Using a combination of reference-free variant calling approaches, we show that no genetic adaptation occurs in either invaded niche during bacterial meningitis for two major pathogen species, Streptococcus pneumoniae and Neisseria meningitidis. This study therefore shows that the bacteria capable of causing meningitis are already able to do this upon entering the blood, and no further sequence change is necessary to cross the blood–brain barrier. Our findings place the focus back on bacterial evolution between nasopharyngeal carriage and invasion, or diversity of the host, as likely mechanisms for determining invasiveness. PMID:28348877

Genome characterization and population genetic structure of the zoonotic pathogen, Streptococcus canis

PubMed Central

2012-01-01

Background Streptococcus canis is an important opportunistic pathogen of dogs and cats that can also infect a wide range of additional mammals including cows where it can cause mastitis. It is also an emerging human pathogen. Results Here we provide characterization of the first genome sequence for this species, strain FSL S3-227 (milk isolate from a cow with an intra-mammary infection). A diverse array of putative virulence factors was encoded by the S. canis FSL S3-227 genome. Approximately 75% of these gene sequences were homologous to known Streptococcal virulence factors involved in invasion, evasion, and colonization. Present in the genome are multiple potentially mobile genetic elements (MGEs) [plasmid, phage, integrative conjugative element (ICE)] and comparison to other species provided convincing evidence for lateral gene transfer (LGT) between S. canis and two additional bovine mastitis causing pathogens (Streptococcus agalactiae, and Streptococcus dysgalactiae subsp. dysgalactiae), with this transfer possibly contributing to host adaptation. Population structure among isolates obtained from Europe and USA [bovine = 56, canine = 26, and feline = 1] was explored. Ribotyping of all isolates and multi locus sequence typing (MLST) of a subset of the isolates (n = 45) detected significant differentiation between bovine and canine isolates (Fisher exact test: P = 0.0000 [ribotypes], P = 0.0030 [sequence types]), suggesting possible host adaptation of some genotypes. Concurrently, the ancestral clonal complex (54% of isolates) occurred in many tissue types, all hosts, and all geographic locations suggesting the possibility of a wide and diverse niche. Conclusion This study provides evidence highlighting the importance of LGT in the evolution of the bacteria S. canis, specifically, its possible role in host adaptation and acquisition of virulence factors. Furthermore, recent LGT detected between S. canis and human bacteria (Streptococcus

Molecular mapping of the cell wall polysaccharides of the human pathogen Streptococcus agalactiae

NASA Astrophysics Data System (ADS)

Beaussart, Audrey; Péchoux, Christine; Trieu-Cuot, Patrick; Hols, Pascal; Mistou, Michel-Yves; Dufrêne, Yves F.

2014-11-01

The surface of many bacterial pathogens is covered with polysaccharides that play important roles in mediating pathogen-host interactions. In Streptococcus agalactiae, the capsular polysaccharide (CPS) is recognized as a major virulence factor while the group B carbohydrate (GBC) is crucial for peptidoglycan biosynthesis and cell division. Despite the important roles of CPS and GBC, there is little information available on the molecular organization of these glycopolymers on the cell surface. Here, we use atomic force microscopy (AFM) and transmission electron microscopy (TEM) to analyze the nanoscale distribution of CPS and GBC in wild-type (WT) and mutant strains of S. agalactiae. TEM analyses reveal that in WT bacteria, peptidoglycan is covered with a very thin (few nm) layer of GBC (the ``pellicle'') overlaid by a 15-45 nm thick layer of CPS (the ``capsule''). AFM-based single-molecule mapping with specific antibody probes shows that CPS is exposed on WT cells, while it is hardly detected on mutant cells impaired in CPS production (ΔcpsE mutant). By contrast, both TEM and AFM show that CPS is over-expressed in mutant cells altered in GBC expression (ΔgbcO mutant), indicating that the production of the two surface glycopolymers is coordinated in WT cells. In addition, AFM topographic imaging and molecular mapping with specific lectin probes demonstrate that removal of CPS (ΔcpsE), but not of GBC (ΔgbcO), leads to the exposure of peptidoglycan, organized into 25 nm wide bands running parallel to the septum. These results indicate that CPS forms a homogeneous barrier protecting the underlying peptidoglycan from environmental exposure, while the presence of GBC does not prevent peptidoglycan detection. This work shows that single-molecule AFM, combined with high-resolution TEM, represents a powerful platform for analysing the molecular arrangement of the cell wall polymers of bacterial pathogens.

Mechanisms of Host-Pathogen Protein Complex Formation and Bacterial Immune Evasion of Streptococcus suis Protein Fhb.

PubMed

Li, Xueqin; Liu, Peng; Gan, Shuzhen; Zhang, Chunmao; Zheng, Yuling; Jiang, Yongqiang; Yuan, Yuan

2016-08-12

Streptococcus suis serotype 2 (S. suis 2)-induced sepsis and meningitis are often accompanied by bacteremia. The evasion of polymorphonuclear leukocyte-mediated phagocytic clearance is central to the establishment of bacteremia caused by S. suis 2 and is facilitated by the ability of factor H (FH)-binding protein (Fhb) to bind FH on the bacterial surface, thereby impeding alternative pathway complement activation and phagocytic clearance. Here, C3b/C3d was found to bind to Fhb, along with FH, forming a large immune complex. The formation of this immune complex was mediated by domain II of Fhb via electrostatic and hydrophobic interactions, which, to our knowledge, is a new type of interaction. Interestingly, Fhb was found to be associated with the cell envelope and also present in the culture supernatant, where secreted Fhb inhibited complement activation via interactions with domain II, thereby enhancing antiphagocytic clearance by polymorphonuclear leukocytes. Thus, Fhb is a multifunctional bacterial protein, which binds host complement component C3 as well as FH and interferes with innate immune recognition in a secret protein manner. S. suis 2 therefore appears to have developed a new strategy to combat host innate immunity and enhance survival in host blood. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

Mechanisms of Host-Pathogen Protein Complex Formation and Bacterial Immune Evasion of Streptococcus suis Protein Fhb*

PubMed Central

Li, Xueqin; Liu, Peng; Gan, Shuzhen; Zhang, Chunmao; Zheng, Yuling; Jiang, Yongqiang; Yuan, Yuan

2016-01-01

Streptococcus suis serotype 2 (S. suis 2)-induced sepsis and meningitis are often accompanied by bacteremia. The evasion of polymorphonuclear leukocyte-mediated phagocytic clearance is central to the establishment of bacteremia caused by S. suis 2 and is facilitated by the ability of factor H (FH)-binding protein (Fhb) to bind FH on the bacterial surface, thereby impeding alternative pathway complement activation and phagocytic clearance. Here, C3b/C3d was found to bind to Fhb, along with FH, forming a large immune complex. The formation of this immune complex was mediated by domain II of Fhb via electrostatic and hydrophobic interactions, which, to our knowledge, is a new type of interaction. Interestingly, Fhb was found to be associated with the cell envelope and also present in the culture supernatant, where secreted Fhb inhibited complement activation via interactions with domain II, thereby enhancing antiphagocytic clearance by polymorphonuclear leukocytes. Thus, Fhb is a multifunctional bacterial protein, which binds host complement component C3 as well as FH and interferes with innate immune recognition in a secret protein manner. S. suis 2 therefore appears to have developed a new strategy to combat host innate immunity and enhance survival in host blood. PMID:27342778

Antibacterial activity and mechanism of action of Monarda punctata essential oil and its main components against common bacterial pathogens in respiratory tract.

PubMed

Li, Hong; Yang, Tian; Li, Fei-Yan; Yao, Yan; Sun, Zhong-Min

2014-01-01

The aim of the current research work was to study the chemical composition of the essential oil of Monarda punctata along with evaluating the essential oil and its major components for their antibacterial effects against some frequently encountered respiratory infection causing pathogens. Gas chromatographic mass spectrometric analysis revealed the presence of 13 chemical constituents with thymol (75.2%), p-cymene (6.7%), limonene (5.4), and carvacrol (3.5%) as the major constituents. The oil composition was dominated by the oxygenated monoterpenes. Antibacterial activity of the essential oil and its major constituents (thymol, p-cymene, limonene) was evaluated against Streptococcus pyogenes, methicillin-resistant Staphylococcus aureus (MRSA), Streptococcus pneumoniae, Haemophilus influenzae and Escherichia coli. The study revealed that the essential oil and its constituents exhibited a broad spectrum and variable degree of antibacterial activity against different strains. Among the tested strains, Streptococcus pyogenes, Escherichia coli and Streptococcus pneumoniae were the most susceptible bacterial strain showing lowest MIC and MBC values. Methicillin-resistant Staphylococcus aureus was the most resistant bacterial strain to the essential oil treatment showing relatively higher MIC and MBC values. Scanning electron microscopy revealed that the essential oil induced potent and dose-dependent membrane damage in S. pyogenes and MRSA bacterial strains. The reactive oxygen species generated by the Monarda punctata essential oil were identified using 2', 7'-dichlorofluorescein diacetate (DCFDA).This study indicated that the Monarda punctata essential oil to a great extent and thymol to a lower extent triggered a substantial increase in the ROS levels in S. pyogenes bacterial cultures which ultimately cause membrane damage as revealed by SEM results.

Antibacterial activity and mechanism of action of Monarda punctata essential oil and its main components against common bacterial pathogens in respiratory tract

PubMed Central

Li, Hong; Yang, Tian; Li, Fei-Yan; Yao, Yan; Sun, Zhong-Min

2014-01-01

The aim of the current research work was to study the chemical composition of the essential oil of Monarda punctata along with evaluating the essential oil and its major components for their antibacterial effects against some frequently encountered respiratory infection causing pathogens. Gas chromatographic mass spectrometric analysis revealed the presence of 13 chemical constituents with thymol (75.2%), p-cymene (6.7%), limonene (5.4), and carvacrol (3.5%) as the major constituents. The oil composition was dominated by the oxygenated monoterpenes. Antibacterial activity of the essential oil and its major constituents (thymol, p-cymene, limonene) was evaluated against Streptococcus pyogenes, methicillin-resistant Staphylococcus aureus (MRSA), Streptococcus pneumoniae, Haemophilus influenzae and Escherichia coli. The study revealed that the essential oil and its constituents exhibited a broad spectrum and variable degree of antibacterial activity against different strains. Among the tested strains, Streptococcus pyogenes, Escherichia coli and Streptococcus pneumoniae were the most susceptible bacterial strain showing lowest MIC and MBC values. Methicillin-resistant Staphylococcus aureus was the most resistant bacterial strain to the essential oil treatment showing relatively higher MIC and MBC values. Scanning electron microscopy revealed that the essential oil induced potent and dose-dependent membrane damage in S. pyogenes and MRSA bacterial strains. The reactive oxygen species generated by the Monarda punctata essential oil were identified using 2’, 7’-dichlorofluorescein diacetate (DCFDA).This study indicated that the Monarda punctata essential oil to a great extent and thymol to a lower extent triggered a substantial increase in the ROS levels in S. pyogenes bacterial cultures which ultimately cause membrane damage as revealed by SEM results. PMID:25550774

Neisseria meningitidis and Streptococcus pneumoniae as leading causes of pediatric bacterial meningitis in nine Mexican hospitals following 3 years of active surveillance

PubMed Central

Chacon-Cruz, Enrique; Martinez-Longoria, Cesar Adrian; Llausas-Magana, Eduardo; Luevanos-Velazquez, Antonio; Vazquez-Narvaez, Jorge Alejandro; Beltran, Sandra; Limon-Rojas, Ana Elena; Urtiz-Jeronimo, Fernando; Castaneda-Narvaez, Jose Luis; Otero-Mendoza, Francisco; Aguilar-Del Real, Fernando; Rodriguez-Chagoyan, Jesus; Rivas-Landeros, Rosa Maria; Volker-Soberanes, Maria Luisa; Hinojosa-Robles, Rosa Maria; Arzate-Barbosa, Patricia; Aviles-Benitez, Laura Karina; Elenes-Zamora, Fernando Ivan; Becka, Chandra M.; Ruttimann, Ricardo

2016-01-01

Objectives: Meningococcal meningitis is reported as a rare condition in Mexico. There are no internationally published studies on bacterial causes of meningitis in the country based on active surveillance. This study focuses on finding the etiology of bacterial meningitis in children from nine Mexican Hospitals. Methods: From January 2010 to February 2013, we conducted a three years of active surveillance for meningitis in nine hospitals throughout Mexico. Active surveillance started at the emergency department for every suspected case, and microbiological studies confirmed/ruled out all potentially bacterial pathogens. We diagnosed based on routine cultures from blood and cerebrospinal fluid (not polymerase chain reaction or other molecular diagnostic tests), and both pneumococcal serotyping and meningococcal serogrouping by using standard methods. Results: Neisseria meningitidis was the leading cause, although 75% of cases occurred in the northwest of the country in Tijuana on the US border. Serogroup C was predominant. Streptococcus pneumoniae followed Neisseria meningitides, but was uniformly distributed throughout the country. Serotype 19A was the most incident but before universal implementation of the 13-valent pneumococcal conjugate vaccine. Other bacteria were much less common, including Enterobacteriaceae and Streptococcus agalactiae (these two affecting mostly young infants). Conclusions: Meningococcal meningitis is endemic in Tijuana, Mexico, and vaccination should be seriously considered in that region. Continuous universal vaccination with the 13-valent pneumococcal conjugate vaccine should be nationally performed, and polymerase chain reaction should be included for bacterial detection in all cultures – negative but presumably bacterial meningitis cases. PMID:27551428

Neisseria meningitidis and Streptococcus pneumoniae as leading causes of pediatric bacterial meningitis in nine Mexican hospitals following 3 years of active surveillance.

PubMed

Chacon-Cruz, Enrique; Martinez-Longoria, Cesar Adrian; Llausas-Magana, Eduardo; Luevanos-Velazquez, Antonio; Vazquez-Narvaez, Jorge Alejandro; Beltran, Sandra; Limon-Rojas, Ana Elena; Urtiz-Jeronimo, Fernando; Castaneda-Narvaez, Jose Luis; Otero-Mendoza, Francisco; Aguilar-Del Real, Fernando; Rodriguez-Chagoyan, Jesus; Rivas-Landeros, Rosa Maria; Volker-Soberanes, Maria Luisa; Hinojosa-Robles, Rosa Maria; Arzate-Barbosa, Patricia; Aviles-Benitez, Laura Karina; Elenes-Zamora, Fernando Ivan; Becka, Chandra M; Ruttimann, Ricardo

2016-01-01

Meningococcal meningitis is reported as a rare condition in Mexico. There are no internationally published studies on bacterial causes of meningitis in the country based on active surveillance. This study focuses on finding the etiology of bacterial meningitis in children from nine Mexican Hospitals. From January 2010 to February 2013, we conducted a three years of active surveillance for meningitis in nine hospitals throughout Mexico. Active surveillance started at the emergency department for every suspected case, and microbiological studies confirmed/ruled out all potentially bacterial pathogens. We diagnosed based on routine cultures from blood and cerebrospinal fluid (not polymerase chain reaction or other molecular diagnostic tests), and both pneumococcal serotyping and meningococcal serogrouping by using standard methods. Neisseria meningitidis was the leading cause, although 75% of cases occurred in the northwest of the country in Tijuana on the US border. Serogroup C was predominant. Streptococcus pneumoniae followed Neisseria meningitides, but was uniformly distributed throughout the country. Serotype 19A was the most incident but before universal implementation of the 13-valent pneumococcal conjugate vaccine. Other bacteria were much less common, including Enterobacteriaceae and Streptococcus agalactiae (these two affecting mostly young infants). Meningococcal meningitis is endemic in Tijuana, Mexico, and vaccination should be seriously considered in that region. Continuous universal vaccination with the 13-valent pneumococcal conjugate vaccine should be nationally performed, and polymerase chain reaction should be included for bacterial detection in all cultures - negative but presumably bacterial meningitis cases.

A Murine Model of Group B Streptococcus Vaginal Colonization.

PubMed

Patras, Kathryn A; Doran, Kelly S

2016-11-16

Streptococcus agalactiae (group B Streptococcus, GBS), is a Gram-positive, asymptomatic colonizer of the human gastrointestinal tract and vaginal tract of 10 - 30% of adults. In immune-compromised individuals, including neonates, pregnant women, and the elderly, GBS may switch to an invasive pathogen causing sepsis, arthritis, pneumonia, and meningitis. Because GBS is a leading bacterial pathogen of neonates, current prophylaxis is comprised of late gestation screening for GBS vaginal colonization and subsequent peripartum antibiotic treatment of GBS-positive mothers. Heavy GBS vaginal burden is a risk factor for both neonatal disease and colonization. Unfortunately, little is known about the host and bacterial factors that promote or permit GBS vaginal colonization. This protocol describes a technique for establishing persistent GBS vaginal colonization using a single β-estradiol pre-treatment and daily sampling to determine bacterial load. It further details methods to administer additional therapies or reagents of interest and to collect vaginal lavage fluid and reproductive tract tissues. This mouse model will further the understanding of the GBS-host interaction within the vaginal environment, which will lead to potential therapeutic targets to control maternal vaginal colonization during pregnancy and to prevent transmission to the vulnerable newborn. It will also be of interest to increase our understanding of general bacterial-host interactions in the female vaginal tract.

Chlorhexidine Digluconate Effects on Planktonic Growth and Biofilm Formation in Some Field Isolates of Animal Bacterial Pathogens

PubMed Central

Ebrahimi, Azizollah; Hemati, Majid; Habibian Dehkordi, Saeed; Bahadoran, Shahab; Khoshnood, Sheida; Khubani, Shahin; Dokht Faraj, Mahdi; Hakimi Alni, Reza

2014-01-01

Background: To study chlorhexidine digluconate disinfectant effects on planktonic growth and biofilm formation in some bacterial field isolates from animals. Objectives: The current study investigated chlorhexidine digluconate effects on planktonic growth and biofilm formation in some field isolates of veterinary bacterial pathogens. Materials and Methods: Forty clinical isolates of Escherichia coli, Salmonella serotypes, Staphylococcus. aureus and Streptococcus agalactiae (10 isolates for each) were examined for chlorhexidine digluconate effects on biofilm formation and planktonic growth using microtiter plates. In all of the examined strains in the presence of chlorhexidine digluconate, biofilm development and planktonic growth were affected at the same concentrations of the disinfectant. Results: Chlorhexidine digluconate inhibited the planktonic growth of different bacterial species at sub-MICs. But they were able to induce biofilm development of the E. coli, Salmonella spp., S. aureus and Str. agalactiae strains. Conclusions: Bacterial resistance against chlorhexidine is increasing. Sub-MIC doses of chlorhexidine digluconate can stimulate the formation of biofilm strains. PMID:24872940

Apoptosis, Toll-like, RIG-I-like and NOD-like Receptors Are Pathways Jointly Induced by Diverse Respiratory Bacterial and Viral Pathogens

PubMed Central

Martínez, Isidoro; Oliveros, Juan C.; Cuesta, Isabel; de la Barrera, Jorge; Ausina, Vicente; Casals, Cristina; de Lorenzo, Alba; García, Ernesto; García-Fojeda, Belén; Garmendia, Junkal; González-Nicolau, Mar; Lacoma, Alicia; Menéndez, Margarita; Moranta, David; Nieto, Amelia; Ortín, Juan; Pérez-González, Alicia; Prat, Cristina; Ramos-Sevillano, Elisa; Regueiro, Verónica; Rodriguez-Frandsen, Ariel; Solís, Dolores; Yuste, José; Bengoechea, José A.; Melero, José A.

2017-01-01

Lower respiratory tract infections are among the top five leading causes of human death. Fighting these infections is therefore a world health priority. Searching for induced alterations in host gene expression shared by several relevant respiratory pathogens represents an alternative to identify new targets for wide-range host-oriented therapeutics. With this aim, alveolar macrophages were independently infected with three unrelated bacterial (Streptococcus pneumoniae, Klebsiella pneumoniae, and Staphylococcus aureus) and two dissimilar viral (respiratory syncytial virus and influenza A virus) respiratory pathogens, all of them highly relevant for human health. Cells were also activated with bacterial lipopolysaccharide (LPS) as a prototypical pathogen-associated molecular pattern. Patterns of differentially expressed cellular genes shared by the indicated pathogens were searched by microarray analysis. Most of the commonly up-regulated host genes were related to the innate immune response and/or apoptosis, with Toll-like, RIG-I-like and NOD-like receptors among the top 10 signaling pathways with over-expressed genes. These results identify new potential broad-spectrum targets to fight the important human infections caused by the bacteria and viruses studied here. PMID:28298903

In Vitro Activity of Delafloxacin against Contemporary Bacterial Pathogens from the United States and Europe, 2014

PubMed Central

Pfaller, M. A.; Sader, H. S.; Rhomberg, P. R.

2017-01-01

ABSTRACT The in vitro activities of delafloxacin and comparator antimicrobial agents against 6,485 bacterial isolates collected from medical centers in Europe and the United States in 2014 were tested. Delafloxacin was the most potent agent tested against methicillin-susceptible Staphylococcus aureus (MSSA), methicillin-resistant S. aureus, Streptococcus pneumoniae, viridans group streptococci, and beta-hemolytic streptococci and had activity similar to that of ciprofloxacin and levofloxacin against certain members of the Enterobacteriaceae. Overall, the broadest coverage of the tested pathogens (Gram-positive cocci and Gram-negative bacilli) was observed with meropenem and tigecycline in both Europe and the United States. Delafloxacin was shown to be active against organisms that may be encountered in acute bacterial skin and skin structure infections, respiratory infections, and urinary tract infections. PMID:28167542

In Vitro Activity of Delafloxacin against Contemporary Bacterial Pathogens from the United States and Europe, 2014.

PubMed

Pfaller, M A; Sader, H S; Rhomberg, P R; Flamm, R K

2017-04-01

The in vitro activities of delafloxacin and comparator antimicrobial agents against 6,485 bacterial isolates collected from medical centers in Europe and the United States in 2014 were tested. Delafloxacin was the most potent agent tested against methicillin-susceptible Staphylococcus aureus (MSSA), methicillin-resistant S. aureus , Streptococcus pneumoniae , viridans group streptococci, and beta-hemolytic streptococci and had activity similar to that of ciprofloxacin and levofloxacin against certain members of the Enterobacteriaceae Overall, the broadest coverage of the tested pathogens (Gram-positive cocci and Gram-negative bacilli) was observed with meropenem and tigecycline in both Europe and the United States. Delafloxacin was shown to be active against organisms that may be encountered in acute bacterial skin and skin structure infections, respiratory infections, and urinary tract infections. Copyright © 2017 Pfaller et al.

Streptococcus agalactiae: a vaginal pathogen?

PubMed

Maniatis, A N; Palermos, J; Kantzanou, M; Maniatis, N A; Christodoulou, C; Legakis, N J

1996-03-01

The significance of Streptococcus agalactiae as an aetiological agent in vaginitis was evaluated. A total of 6226 samples from women who presented with vaginal symptoms was examined. The presence of >10 leucocytes/high-power field (h.p.f.) was taken to be the criterion of active infection. S. agalactiae was isolated from 10.1% of these samples. The isolation rates of other common pathogens such as Candida spp., Gardnerella vaginalis and Trichomonas spp. were 54.1%, 27.2% and 4.2%, respectively, in the same group of patients. In contrast, the isolation rates of these micro-organisms in the group of patients who had no infection (<10 leucocytes/h.p.f.) were 4.2%, 38.3%, 33% and 0.5%, respectively. In the majority of samples from which S. agalactiae was isolated, it was the sole pathogen isolated (83%) and its presence was associated with an inflammatory response in 80% of patients. Furthermore, the relative risk of vaginal infection with S. agalactiae (2.38) in patients with purulent vaginal discharge was greater than that of Candida spp. infection (1.41) and lower than that of Trichomonas spp. infection (8.32). These data suggest that S. agalactiae in symptomatic women with microscopic evidence of inflammation should be considered a causative agent of vaginitis.

Evolving trends of neonatal and childhood bacterial meningitis in northern Taiwan.

PubMed

Lin, Meng-Chin; Chiu, Nan-Chang; Chi, Hsin; Ho, Che-Sheng; Huang, Fu-Yuan

2015-06-01

The epidemiology of bacterial meningitis varies in different areas, age groups, and times. To know the trend of neonatal and childhood bacterial meningitis in northern Taiwan, we performed this 29-year-long assessment. Eligible patients were aged 18 years or younger, hospitalized in Mackay Memorial Hospital between 1984 and 2012, and proven by positive cerebrospinal fluid bacterial cultures. Analysis included the patient numbers and pathogens in different age groups, periods, complications, and outcomes. Males were predominant in all the age groups through the years. Almost half of the patients were in the neonatal period. Patient numbers went up in the early study period and declined after 1993-1997. Group B Streptococcus and Escherichia coli were the most common pathogens in neonates, whereas in childhood were Streptococcus pneumoniae and Haemophilus influenzae type b (Hib). Patient numbers of Group B Streptococcus, S. pneumoniae, and Hib meningitis declined in the late study period, but E. coli meningitis increased. The mortality rate decreased but sequela rate increased. Among the four most common pathogens, S. pneumoniae had the worst outcome and had highest mortality rate. All Hib meningitis patients survived, but their sequela rate was the highest. This study provides an epidemiological data on trends of neonatal and childhood bacterial meningitis in northern Taiwan during the past 29 years, including male and neonatal predominance, decrease of total patient number in recent years, change of major pathogens, and declined mortality but raised morbidity. Copyright © 2013. Published by Elsevier B.V.

Role of Streptococcus sanguinis sortase A in bacterial colonization.

PubMed

Yamaguchi, Masaya; Terao, Yutaka; Ogawa, Taiji; Takahashi, Toshihito; Hamada, Shigeyuki; Kawabata, Shigetada

2006-10-01

Streptococcus sanguinis, a normal inhabitant of the human oral cavity, has low cariogenicity, though colonization on tooth surfaces by this bacterium initiates aggregation by other oral bacteria and maturation of dental plaque. Additionally, S. sanguinis is frequently isolated from infective endocarditis patients. We investigated the functions of sortase A (SrtA), which cleaves LPXTG-containing proteins and anchors them to the bacterial cell wall, as a possible virulence factor of S. sanguinis. We identified the srtA gene of S. sanguinis by searching a homologous gene of Streptococcus mutans in genome databases. Next, we constructed an srtA-deficient mutant strain of S. sanguinis by insertional inactivation and compared it to the wild type strain. In the case of the mutant strain, some surface proteins could not anchor to the cell wall and were partially released into the culture supernatant. Furthermore, adherence to saliva-coated hydroxyapatite beads and polystyrene plates, as well as adherence to and invasion of human epithelial cells were reduced significantly in the srtA-deficient strain when compared to the wild type. In addition, antiopsonization levels and bacterial survival of the srtA-deficient mutant were decreased in human whole blood. This is the first known study to report that SrtA contributes to antiopsonization in streptococci. Our results suggest that SrtA anchors surface adhesins as well as some proteins that function as antiopsonic molecules as a means of evading the human immune system. Furthermore, they demonstrate that SrtA of S. sanguinis plays important roles in bacterial colonization.

Genome analysis of multiple pathogenic isolates of Streptococcus agalactiae: Implications for the microbial “pan-genome”

PubMed Central

Tettelin, Hervé; Masignani, Vega; Cieslewicz, Michael J.; Donati, Claudio; Medini, Duccio; Ward, Naomi L.; Angiuoli, Samuel V.; Crabtree, Jonathan; Jones, Amanda L.; Durkin, A. Scott; DeBoy, Robert T.; Davidsen, Tanja M.; Mora, Marirosa; Scarselli, Maria; Margarit y Ros, Immaculada; Peterson, Jeremy D.; Hauser, Christopher R.; Sundaram, Jaideep P.; Nelson, William C.; Madupu, Ramana; Brinkac, Lauren M.; Dodson, Robert J.; Rosovitz, Mary J.; Sullivan, Steven A.; Daugherty, Sean C.; Haft, Daniel H.; Selengut, Jeremy; Gwinn, Michelle L.; Zhou, Liwei; Zafar, Nikhat; Khouri, Hoda; Radune, Diana; Dimitrov, George; Watkins, Kisha; O'Connor, Kevin J. B.; Smith, Shannon; Utterback, Teresa R.; White, Owen; Rubens, Craig E.; Grandi, Guido; Madoff, Lawrence C.; Kasper, Dennis L.; Telford, John L.; Wessels, Michael R.; Rappuoli, Rino; Fraser, Claire M.

2005-01-01

The development of efficient and inexpensive genome sequencing methods has revolutionized the study of human bacterial pathogens and improved vaccine design. Unfortunately, the sequence of a single genome does not reflect how genetic variability drives pathogenesis within a bacterial species and also limits genome-wide screens for vaccine candidates or for antimicrobial targets. We have generated the genomic sequence of six strains representing the five major disease-causing serotypes of Streptococcus agalactiae, the main cause of neonatal infection in humans. Analysis of these genomes and those available in databases showed that the S. agalactiae species can be described by a pan-genome consisting of a core genome shared by all isolates, accounting for ≈80% of any single genome, plus a dispensable genome consisting of partially shared and strain-specific genes. Mathematical extrapolation of the data suggests that the gene reservoir available for inclusion in the S. agalactiae pan-genome is vast and that unique genes will continue to be identified even after sequencing hundreds of genomes. PMID:16172379

Comparison of direct-plating and broth-enrichment culture methods for detection of potential bacterial pathogens in respiratory secretions.

PubMed

Kaur, Ravinder; Wischmeyer, Jareth; Morris, Matthew; Pichichero, Michael E

2017-11-01

We compared the recovery of potential respiratory bacterial pathogens and normal flora from nasopharyngeal specimens collected from children during health and at the onset of acute otitis media (AOM) by selective direct-plating and overnight broth-enrichment. Overall, 3442 nasal wash (NW) samples collected from young children were analysed from a 10-year prospective study. NWs were cultured by (1) direct-plating to TSAII/5 % sheep blood agar and chocolate agar plates and (2) overnight broth-enrichment in BacT/ALERT SA-broth followed by plating. Standard microbiology techniques were applied to identify three dominant respiratory bacterial pathogens: Streptococcus pneumoniae (Spn), Haemophilus influenzae (Hflu) and Moraxella catarrhalis (Mcat) as well as two common nasal flora, Staphylococcus aureus (SA) and alpha-haemolytic Streptococci (AHS).Results/Key findings. Direct-plating of NW resulted in isolation of Spn from 37.8 %, Hflu from 13.6 % and Mcat from 33.2 % of samples. In comparison, overnight broth-enrichment isolated fewer Spn (30.1 %), Hflu (6.2 %) and Mcat (16.2 %) (P<0.001-0.0001). Broth-enrichment resulted in significant increased isolation of SA (6.0 %) and AHS (30.1 %) (P<0.0001). Competition between bacterial species in broth when both species were detected by direct-plating was assessed, and it was found that SA and AHS out-competed other species during broth-enrichment when samples were collected from healthy children but not during AOM. In middle ear fluids (MEF) at the onset of AOM, broth-enrichment resulted in higher recovery of Spn (+10.4 %, P<0.001), Hflu (+4.4 %, P=0.39) and Mcat (+13.5 %, <0.001). Broth-enrichment significantly reduces the accurate detection of bacterial respiratory pathogens and increases identification of SA and AHS in NW. Broth-enrichment improves detection of bacterial respiratory pathogens in MEF samples.

The Impact of Oxygen on Bacterial Enteric Pathogens.

PubMed

Wallace, N; Zani, A; Abrams, E; Sun, Y

2016-01-01

Bacterial enteric pathogens are responsible for a tremendous amount of foodborne illnesses every year through the consumption of contaminated food products. During their transit from contaminated food sources to the host gastrointestinal tract, these pathogens are exposed and must adapt to fluctuating oxygen levels to successfully colonize the host and cause diseases. However, the majority of enteric infection research has been conducted under aerobic conditions. To raise awareness of the importance in understanding the impact of oxygen, or lack of oxygen, on enteric pathogenesis, we describe in this review the metabolic and physiological responses of nine bacterial enteric pathogens exposed to environments with different oxygen levels. We further discuss the effects of oxygen levels on virulence regulation to establish potential connections between metabolic adaptations and bacterial pathogenesis. While not providing an exhaustive list of all bacterial pathogens, we highlight key differences and similarities among nine facultative anaerobic and microaerobic pathogens in this review to argue for a more in-depth understanding of the diverse impact oxygen levels have on enteric pathogenesis. Copyright © 2016 Elsevier Inc. All rights reserved.

Comparison of Pathogen Eradication Rate and Safety of Anti-Bacterial Agents for Bronchitis: A Network Meta-Analysis.

PubMed

Wang, Jinghua; Xu, Haiyang; Wang, Dunwei; Li, Mingxian

2017-10-01

A large number of population in both developing and developed countries are affected by bronchitis, among all the factors, bacterial infection was considered as a critical cause of acute exacerbations of chronic bronchitis. Although several anti-bacterial agents were proved to have the effect of alleviating bronchitis, their relative efficacies and potential side effects remained not clear. We are keen to compare the pathogen eradication rate and safety of anti-bacterial agents for bronchitis. Relevant studies were searched in multiple sources and data were extracted from eligible studies. Then conventional meta-analysis and network meta-analysis (NMA) were conducted to determine the relative efficacy and safety of bronchitis medications. The efficacy of bronchitis medications was determined by using the outcome of pathogen eradication, including total pathogen eradication, pathogen eradication of Haemophilus influenzae, pathogen eradication of Moraxella catarrhalis, and pathogen eradication of Streptococcus pneumoniae. In addition, safety was assessed by using the outcome of adverse effects and diarrhoea. A 27 RCTs with 9,414 participants were included in the study. Among the medications, gatifloxacin and moxifloxacin exhibited better performance than clarithromycin with respect to pathogen eradication of H. influenzae (OR = 21.37, CI: 1.22-541.28; OR = 7.43, CI: 1.79-30.50). Clarithromycin, gemifloxacin, levofloxacin, moxifloxacin, and telithromycin appeared to be more preferable than amoxicillin + clavulanate and azithromycin with respect to diarrhoea (all OR <1). The surface under the cumulative ranking curve (SUCRA) results suggested that gemifloxacin and levofloxacin had a relatively high ranking in total pathogen eradication, whereas amoxicillin + clavulanate and azithromycin exhibited relatively lower ranking with respect to adverse effects and diarrhoea. Gemifloxacin and levofloxacin are more preferable than others for lowering respiratory

Bacterial Pathogens versus Autophagy: Implications for Therapeutic Interventions

PubMed Central

Kimmey, Jacqueline M.; Stallings, Christina L.

2016-01-01

Research in recent years has focused significantly on the role of selective macroautophagy in targeting intracellular pathogens for lysosomal degradation, a process termed xenophagy. In this review we evaluate the proposed roles for xenophagy in controlling bacterial infection, highlighting the concept that successful pathogens have evolved ways to subvert or exploit this defense, minimizing the actual effectiveness of xenophagy in innate immunity. Instead, studies in animal models have revealed that autophagy-associated proteins often function outside of xenophagy to influence bacterial pathogenesis. In light of current efforts to manipulate autophagy and the development of host-directed therapies to fight bacterial infections, we also discuss the implications stemming from the complicated relationship that exists between autophagy and bacterial pathogens. PMID:27866924

The role of coagulation/fibrinolysis during Streptococcus pyogenes infection.

PubMed

Loof, Torsten G; Deicke, Christin; Medina, Eva

2014-01-01

The hemostatic system comprises platelet aggregation, coagulation and fibrinolysis and is a host defense mechanism that protects the integrity of the vascular system after tissue injury. During bacterial infections, the coagulation system cooperates with the inflammatory system to eliminate the invading pathogens. However, pathogenic bacteria have frequently evolved mechanisms to exploit the hemostatic system components for their own benefit. Streptococcus pyogenes, also known as Group A Streptococcus, provides a remarkable example of the extraordinary capacity of pathogens to exploit the host hemostatic system to support microbial survival and dissemination. The coagulation cascade comprises the contact system (also known as the intrinsic pathway) and the tissue factor pathway (also known as the extrinsic pathway), both leading to fibrin formation. During the early phase of S. pyogenes infection, the activation of the contact system eventually leads to bacterial entrapment within a fibrin clot, where S. pyogenes is immobilized and killed. However, entrapped S. pyogenes can circumvent the antimicrobial effect of the clot by sequestering host plasminogen on the bacterial cell surface that, after conversion into its active proteolytic form, plasmin, degrades the fibrin network and facilitates the liberation of S. pyogenes from the clot. Furthermore, the surface-localized fibrinolytic activity also cleaves a variety of extracellular matrix proteins, thereby enabling S. pyogenes to migrate across barriers and disseminate within the host. This review summarizes the knowledge gained during the last two decades on the role of coagulation/fibrinolysis in host defense against S. pyogenes as well as the strategies developed by this pathogen to evade and exploit these host mechanisms for its own benefit.

[New insight into bacterial zoonotic pathogens posing health hazards to humans].

PubMed

Ciszewski, Marcin; Czekaj, Tomasz; Szewczyk, Eligia Maria

2014-01-01

This article presents the problem of evolutionary changes of zoonotic pathogens responsible for human diseases. Everyone is exposed to the risk of zoonotic infection, particularly employees having direct contact with animals, i.e. veterinarians, breeders, butchers and workers of animal products' processing industry. The article focuses on pathogens monitored by the European Centre for Disease Prevention and Control (ECDC), which has been collecting statistical data on zoonoses from all European Union countries for 19 years and publishing collected data in annual epidemiological reports. Currently, the most important 11 pathogens responsible for causing human zoonotic diseases are being monitored, of which seven are bacteria: Salmonella spp., Campylobacter spp., Listeria monocytogenes, Mycobacterium bovis, Brucella spp., Coxiella burnetti and Verotoxin-producing E. coli (VTEC)/Shiga-like toxin producing E. coli (STEC). As particularly important are considered foodborne pathogens. The article also includes new emerging zoonotic bacteria, which are not currently monitored by ECDC but might pose a serious epidemiological problem in a foreseeable future: Streptococcus iniae, S. suis, S. dysgalactiae and staphylococci: Staphylococcus intermedius, S. pseudintermedius. Those species have just crossed the animal-human interspecies barrier. The exact mechanism of this phenomenon remains unknown, it is connected, however, with genetic variability, capability to survive in changing environment. These abilities derive from DNA rearrangement and horizontal gene transfer between bacterial cells. Substantial increase in the number of scientific publications on this subject, observed over the last few years, illustrates the importance of the problem.

The Protein Interactome of Streptococcus pneumoniae and Bacterial Meta-interactomes Improve Function Predictions.

PubMed

Wuchty, S; Rajagopala, S V; Blazie, S M; Parrish, J R; Khuri, S; Finley, R L; Uetz, P

2017-01-01

The functions of roughly a third of all proteins in Streptococcus pneumoniae , a significant human-pathogenic bacterium, are unknown. Using a yeast two-hybrid approach, we have determined more than 2,000 novel protein interactions in this organism. We augmented this network with meta-interactome data that we defined as the pool of all interactions between evolutionarily conserved proteins in other bacteria. We found that such interactions significantly improved our ability to predict a protein's function, allowing us to provide functional predictions for 299 S. pneumoniae proteins with previously unknown functions. IMPORTANCE Identification of protein interactions in bacterial species can help define the individual roles that proteins play in cellular pathways and pathogenesis. Very few protein interactions have been identified for the important human pathogen S. pneumoniae . We used an experimental approach to identify over 2,000 new protein interactions for S. pneumoniae , the most extensive interactome data for this bacterium to date. To predict protein function, we used our interactome data augmented with interactions from other closely related bacteria. The combination of the experimental data and meta-interactome data significantly improved the prediction results, allowing us to assign possible functions to a large number of poorly characterized proteins.

The Protein Interactome of Streptococcus pneumoniae and Bacterial Meta-interactomes Improve Function Predictions

PubMed Central

Rajagopala, S. V.; Blazie, S. M.; Parrish, J. R.; Khuri, S.; Finley, R. L.

2017-01-01

ABSTRACT The functions of roughly a third of all proteins in Streptococcus pneumoniae, a significant human-pathogenic bacterium, are unknown. Using a yeast two-hybrid approach, we have determined more than 2,000 novel protein interactions in this organism. We augmented this network with meta-interactome data that we defined as the pool of all interactions between evolutionarily conserved proteins in other bacteria. We found that such interactions significantly improved our ability to predict a protein’s function, allowing us to provide functional predictions for 299 S. pneumoniae proteins with previously unknown functions. IMPORTANCE Identification of protein interactions in bacterial species can help define the individual roles that proteins play in cellular pathways and pathogenesis. Very few protein interactions have been identified for the important human pathogen S. pneumoniae. We used an experimental approach to identify over 2,000 new protein interactions for S. pneumoniae, the most extensive interactome data for this bacterium to date. To predict protein function, we used our interactome data augmented with interactions from other closely related bacteria. The combination of the experimental data and meta-interactome data significantly improved the prediction results, allowing us to assign possible functions to a large number of poorly characterized proteins. PMID:28744484

Streptococcus massiliensis in the human mouth: a phylogenetic approach for the inference of bacterial habitats.

PubMed

Póntigo, F; Silva, C; Moraga, M; Flores, S V

2015-12-29

Streptococcus is a diverse bacterial lineage. Species of this genus occupy a myriad of environments inside humans and other animals. Despite the elucidation of several of these habitats, many remain to be identified. Here, we explore a methodological approach to reveal unknown bacterial environments. Specifically, we inferred the phylogeny of the Mitis group by analyzing the sequences of eight genes. In addition, information regarding habitat use of species belonging to this group was obtained from the scientific literature. The oral cavity emerged as a potential, previously unknown, environment of Streptococcus massiliensis. This phylogeny-based prediction was confirmed by species-specific polymerase chain reaction (PCR) amplification. We propose employing a similar approach, i.e., use of bibliographic data and molecular phylogenetics as predictive methods, and species-specific PCR as confirmation, in order to reveal other unknown habitats in further bacterial taxa.

Streptococcus pyogenes meningitis: report of a case and review of the literature.

PubMed

Berner, R; Herdeg, S; Gordjani, N; Brandis, M

2000-07-01

Streptococcus pyogenes is a very uncommon cause of bacterial meningitis beyond the neonatal period. A case report and a review of the recent literature is presented. We report on a previously healthy 7-year-old boy who developed S. pyogenes meningitis following a 2-day history of otitis media. A CT scan revealed right-sided mastoiditis as a possible focus of infection. The patient was treated with penicillin G for 14 days. The clinical course was uneventful, and the recovered without sequelae. By means of the polymerase chain reaction, the presence of streptococcal pyrogenic exotoxin (SPE) B and SPE C, but not SPE A genes was discovered from the bacterial DNA. Streptococcus pyogenes is a rare cause of bacterial meningitis but has to be considered as the causative pathogen beyond the neonatal period.

Controlled Human Infection for Vaccination Against Streptococcus Pyogenes

ClinicalTrials.gov

2018-06-26

Streptococcus Pyogenes Pharyngitis; Streptococcus Pharyngitis; Strep Throat; Streptococcus Pyogenes Infection; Group A Streptococcus: B Hemolytic Pharyngitis; Group A Streptococcal Infection; Gram-Positive Bacterial Infections; Bacterial Infections

Bath immersion, booster vaccination strategy holds potential for protecting juvenile tilapia against Streptococcus iniae

USDA-ARS?s Scientific Manuscript database

Streptococcus iniae is a significant bacterial pathogen that causes hemorrhagic septicemia and meningoencephalitis in tilapia, hybrid striped bass, rainbow trout, olive flounder, yellowtail, barramundi and other species of cultured and wild fish worldwide. In tilapia production, vaccination of fry ...

Sequential necrotizing fasciitis caused by the monomicrobial pathogens Streptococcus equisimilis and extended-spectrum beta-lactamase-producing Escherichia coli.

PubMed

Endo, Akiko; Matsuoka, Ryosuke; Mizuno, Yasushi; Doi, Asako; Nishioka, Hiroaki

2016-08-01

Necrotizing fasciitis is a rapidly progressing bacterial infection of the superficial fascia and subcutaneous tissue that is associated with a high mortality rate and is caused by a single species of bacteria or polymicrobial organisms. Escherichia coli is rarely isolated from patients with monomicrobial disease. Further, there are few reports of extended-spectrum beta-lactamase (ESBL)-producing E. coli associated with necrotizing fasciitis. We report here our treatment of an 85-year-old man who was admitted because of necrotizing fasciitis of his right thigh. Streptococcus equisimilis was detected as a monomicrobial pathogen, and the infection was cured by amputation of the patient's right leg and the administration of antibiotics. However, 5 days after discontinuing antibiotic therapy, he developed necrotizing fasciitis on his right upper limb and died. ESBL-producing E. coli was the only bacterial species isolated from blood and skin cultures. This case demonstrates that ESBL-producing E. coli can cause monomicrobial necrotizing fasciitis, particularly during hospitalization and that a different bacterial species can cause disease shortly after a previous episode. Copyright © 2016 Japanese Society of Chemotherapy and The Japanese Association for Infectious Diseases. Published by Elsevier Ltd. All rights reserved.

Effects of Benzalkonium Chloride on Planktonic Growth and Biofilm Formation by Animal Bacterial Pathogens

PubMed Central

Ebrahimi, Azizollah; Hemati, Majid; Shabanpour, Ziba; Habibian Dehkordi, Saeed; Bahadoran, Shahab; Lotfalian, Sharareh; Khubani, Shahin

2015-01-01

Background: Resistance toward quaternary ammonium compounds (QACs) is widespread among a diverse range of microorganisms and is facilitated by several mechanisms such as biofilm formation. Objectives: In this study, the effects of benzalkonium chloride on planktonic growth and biofilm formation by some field isolates of animal bacterial pathogens were investigated. Materials and Methods: Forty clinical isolates of Escherichia coli, Salmonella serotypes, Staphylococcus aureus and Streptococcus agalactiae (10 isolates of each) were examined for effects of benzalkonium chloride on biofilm formation and planktonic growth using microtiter plates. For all the examined strains in the presence of benzalkonium chloride, biofilm development and planktonic growth were affected at the same concentrations of disinfectant. Results: The means of strains growth increase after the minimal inhibitory concentration (MIC) were significant in all the bacteria (except for E. coli in 1/32 and S. agalactiae in of 1/8 MIC). Biofilm formation increased with decrease of antiseptics concentration; a significant increase was found in all the samples. The most turbidity related to S. aureus and the least to Salmonella. Conclusions: Bacterial resistance against quaternary ammonium compounds is increasing which can increase the bacterial biofilm formation. PMID:25793094

The role of coagulation/fibrinolysis during Streptococcus pyogenes infection

PubMed Central

Loof, Torsten G.; Deicke, Christin; Medina, Eva

2014-01-01

The hemostatic system comprises platelet aggregation, coagulation and fibrinolysis and is a host defense mechanism that protects the integrity of the vascular system after tissue injury. During bacterial infections, the coagulation system cooperates with the inflammatory system to eliminate the invading pathogens. However, pathogenic bacteria have frequently evolved mechanisms to exploit the hemostatic system components for their own benefit. Streptococcus pyogenes, also known as Group A Streptococcus, provides a remarkable example of the extraordinary capacity of pathogens to exploit the host hemostatic system to support microbial survival and dissemination. The coagulation cascade comprises the contact system (also known as the intrinsic pathway) and the tissue factor pathway (also known as the extrinsic pathway), both leading to fibrin formation. During the early phase of S. pyogenes infection, the activation of the contact system eventually leads to bacterial entrapment within a fibrin clot, where S. pyogenes is immobilized and killed. However, entrapped S. pyogenes can circumvent the antimicrobial effect of the clot by sequestering host plasminogen on the bacterial cell surface that, after conversion into its active proteolytic form, plasmin, degrades the fibrin network and facilitates the liberation of S. pyogenes from the clot. Furthermore, the surface-localized fibrinolytic activity also cleaves a variety of extracellular matrix proteins, thereby enabling S. pyogenes to migrate across barriers and disseminate within the host. This review summarizes the knowledge gained during the last two decades on the role of coagulation/fibrinolysis in host defense against S. pyogenes as well as the strategies developed by this pathogen to evade and exploit these host mechanisms for its own benefit. PMID:25309880

Primer prueba de desafio controlado en tilapia del Nilo Para Resistencia a Streptococcus iniae

USDA-ARS?s Scientific Manuscript database

Intensification of tilapia production has resulted in disease outbreaks that negatively affect commercial fish farmers. One bacterial pathogen that commonly causes losses in tilapia production is Streptococcus iniae. Control and prevention of S. iniae can be difficult and requires an integrated fish...

Xylella genomics and bacterial pathogenicity to plants.

PubMed

Dow, J M; Daniels, M J

2000-12-01

Xylella fastidiosa, a pathogen of citrus, is the first plant pathogenic bacterium for which the complete genome sequence has been published. Inspection of the sequence reveals high relatedness to many genes of other pathogens, notably Xanthomonas campestris. Based on this, we suggest that Xylella possesses certain easily testable properties that contribute to pathogenicity. We also present some general considerations for deriving information on pathogenicity from bacterial genomics. Copyright 2000 John Wiley & Sons, Ltd.

Vaccine development for protection against systemic infections with Streptococcus suis and Haemophilus parasuis in swine

USDA-ARS?s Scientific Manuscript database

Both Streptococcus suis and Haemophilus parasuis are important invasive bacterial pathogens of swine, commonly causing meningitis, arthritis, polyserositis, and septicemia. Due to the presence of many serotypes and high genotypic variability, efficacious vaccines are not readily available. We are us...

Within-host evolution of bacterial pathogens

PubMed Central

Didelot, Xavier; Walker, A. Sarah; Peto, Tim E.; Crook, Derrick W.; Wilson, Daniel J.

2016-01-01

Whole genome sequencing has opened the way to investigating the dynamics and genomic evolution of bacterial pathogens during colonization and infection of humans. The application of this technology to the longitudinal study of adaptation in the infected host — in particular, the evolution of drug resistance and host adaptation in patients chronically infected with opportunistic pathogens — has revealed remarkable patterns of convergent evolution, pointing to an inherent repeatability of evolution. In this Review, we describe how these studies have advanced our understanding of the mechanisms and principles of within-host genome evolution, and we consider the consequences of findings such as a potent adaptive potential for pathogenicity. Finally, we discuss the possibility that genomics may be used in the future to predict the clinical progression of bacterial infections, and to suggest the best treatment option. PMID:26806595

Within-host evolution of bacterial pathogens.

PubMed

Didelot, Xavier; Walker, A Sarah; Peto, Tim E; Crook, Derrick W; Wilson, Daniel J

2016-03-01

Whole-genome sequencing has opened the way for investigating the dynamics and genomic evolution of bacterial pathogens during the colonization and infection of humans. The application of this technology to the longitudinal study of adaptation in an infected host--in particular, the evolution of drug resistance and host adaptation in patients who are chronically infected with opportunistic pathogens--has revealed remarkable patterns of convergent evolution, suggestive of an inherent repeatability of evolution. In this Review, we describe how these studies have advanced our understanding of the mechanisms and principles of within-host genome evolution, and we consider the consequences of findings such as a potent adaptive potential for pathogenicity. Finally, we discuss the possibility that genomics may be used in the future to predict the clinical progression of bacterial infections and to suggest the best option for treatment.

Screening of binding activity of Streptococcus pneumoniae, Streptococcus agalactiae and Streptococcus suis to berries and juices.

PubMed

Toivanen, Marko; Huttunen, Sanna; Duricová, Jana; Soininen, Pasi; Laatikainen, Reino; Loimaranta, Vuokko; Haataja, Sauli; Finne, Jukka; Lapinjoki, Seppo; Tikkanen-Kaukanen, Carina

2010-01-01

Antiadhesion therapy is a promising approach to the fight against pathogens. Antibiotic resistance and the lack of effective vaccines have increased the search for new methods to prevent infectious diseases. Previous studies have shown the antiadhesion activity of juice from cultivated cranberries (Vaccinium macrocarpon Ait.) against bacteria, especially E. coli. In this study, the binding of two streptococcal strains, Streptococcus pneumoniae and Streptococcus agalactiae, to molecular size fractions (FI, FII and FIII, <10 kDa, 10-100 kDa, and >100 kDa, respectively) of berries and berry and fruit juices from 12 plant species were studied using a microtiter well assay. For Streptococcus suis a hemagglutination inhibition assay was used. In general, binding activity was detected especially to wild cranberry (Vaccinium oxycoccos L.) and to other Vaccinium species. S. pneumoniae cells bound most to cranberry juice fraction FI and S. agalactiae cells to cranberry fraction FIII. Hemagglutination induced by S. suis was most effectively inhibited by cranberry fraction FII. NMR spectra of some characteristic active and non-active fractions were also measured. They indicate that fractions FII and FIII contained proanthocyanidins and/or other phenolic compounds. The results suggest Vaccinium berries as possible sources of antiadhesives against bacterial infections.

The RNA-binding protein tristetraprolin schedules apoptosis of pathogen-engaged neutrophils during bacterial infection

PubMed Central

Ebner, Florian; Ivin, Masa; Kratochvill, Franz; Gratz, Nina; Villunger, Andreas; Sixt, Michael

2017-01-01

Protective responses against pathogens require a rapid mobilization of resting neutrophils and the timely removal of activated ones. Neutrophils are exceptionally short-lived leukocytes, yet it remains unclear whether the lifespan of pathogen-engaged neutrophils is regulated differently from that in the circulating steady-state pool. Here, we have found that under homeostatic conditions, the mRNA-destabilizing protein tristetraprolin (TTP) regulates apoptosis and the numbers of activated infiltrating murine neutrophils but not neutrophil cellularity. Activated TTP-deficient neutrophils exhibited decreased apoptosis and enhanced accumulation at the infection site. In the context of myeloid-specific deletion of Ttp, the potentiation of neutrophil deployment protected mice against lethal soft tissue infection with Streptococcus pyogenes and prevented bacterial dissemination. Neutrophil transcriptome analysis revealed that decreased apoptosis of TTP-deficient neutrophils was specifically associated with elevated expression of myeloid cell leukemia 1 (Mcl1) but not other antiapoptotic B cell leukemia/lymphoma 2 (Bcl2) family members. Higher Mcl1 expression resulted from stabilization of Mcl1 mRNA in the absence of TTP. The low apoptosis rate of infiltrating TTP-deficient neutrophils was comparable to that of transgenic Mcl1-overexpressing neutrophils. Our study demonstrates that posttranscriptional gene regulation by TTP schedules the termination of the antimicrobial engagement of neutrophils. The balancing role of TTP comes at the cost of an increased risk of bacterial infections. PMID:28504646

Exploiting Quorum Sensing To Confuse Bacterial Pathogens

PubMed Central

LaSarre, Breah

2013-01-01

SUMMARY Cell-cell communication, or quorum sensing, is a widespread phenomenon in bacteria that is used to coordinate gene expression among local populations. Its use by bacterial pathogens to regulate genes that promote invasion, defense, and spread has been particularly well documented. With the ongoing emergence of antibiotic-resistant pathogens, there is a current need for development of alternative therapeutic strategies. An antivirulence approach by which quorum sensing is impeded has caught on as a viable means to manipulate bacterial processes, especially pathogenic traits that are harmful to human and animal health and agricultural productivity. The identification and development of chemical compounds and enzymes that facilitate quorum-sensing inhibition (QSI) by targeting signaling molecules, signal biogenesis, or signal detection are reviewed here. Overall, the evidence suggests that QSI therapy may be efficacious against some, but not necessarily all, bacterial pathogens, and several failures and ongoing concerns that may steer future studies in productive directions are discussed. Nevertheless, various QSI successes have rightfully perpetuated excitement surrounding new potential therapies, and this review highlights promising QSI leads in disrupting pathogenesis in both plants and animals. PMID:23471618

Bacteriophage remediation of bacterial pathogens in aquaculture: a review of the technology

PubMed Central

Richards, Gary P

2014-01-01

Bacteriophages have been proposed as an alternative to antibiotic usage and several studies on their application in aquaculture have been reported. This review highlights progress to date on phage therapies for the following fish and shellfish diseases and associated pathogens: hemorrhagic septicemia (Aeromonas hydrophila) in loaches, furunculosis (Aeromonas salmonicida) in trout and salmon, edwardsiellosis (Edwardsiella tarda) in eel, columnaris disease (Flavobacterium columnare) in catfish, rainbow trout fry syndrome or cold water disease (Flavobacterium psychrophilum) in trout and salmon, lactococcosis (Lactococcus spp.) in yellowtail, ulcerative skin lesions (Pseudomonas aeruginosa) in freshwater catfish, bacterial hemorrhagic ascites disease (Pseudomonas plecoglossicida) in ayu fish, streptococcosis (Streptococcus iniae) in flounder, and luminescent vibriosis (Vibrio harveyi) in shrimp. Information is reviewed on phage specificity, host resistance, routes of administration, and dosing of fish and shellfish. Limitations in phage research are described and recommended guidelines are provided for conducting future phage studies involving fish and shellfish. PMID:26713223

Risk factors for community-acquired bacterial meningitis.

PubMed

Lundbo, Lene Fogt; Benfield, Thomas

2017-06-01

Bacterial meningitis is a significant burden of disease and mortality in all age groups worldwide despite the development of effective conjugated vaccines. The pathogenesis of bacterial meningitis is based on complex and incompletely understood host-pathogen interactions. Some of these are pathogen-specific, while some are shared between different bacteria. We searched the database PubMed to identify host risk factors for bacterial meningitis caused by the pathogens Streptococcus pneumoniae, Neisseria meningitidis and Haemophilus influenzae type b, because they are three most common causative bacteria beyond the neonatal period. We describe a number of risk factors; including socioeconomic factors, age, genetic variation of the host and underlying medical conditions associated with increased susceptibility to invasive bacterial infections in both children and adults. As conjugated vaccines are available for these infections, it is of utmost importance to identify high risk patients to be able to prevent invasive disease.

A hemolytic pigment of Group B Streptococcus allows bacterial penetration of human placenta

PubMed Central

Whidbey, Christopher; Harrell, Maria Isabel; Burnside, Kellie; Ngo, Lisa; Becraft, Alexis K.; Iyer, Lakshminarayan M.; Aravind, L.; Hitti, Jane

2013-01-01

Microbial infection of the amniotic fluid is a significant cause of fetal injury, preterm birth, and newborn infections. Group B Streptococcus (GBS) is an important human bacterial pathogen associated with preterm birth, fetal injury, and neonatal mortality. Although GBS has been isolated from amniotic fluid of women in preterm labor, mechanisms of in utero infection remain unknown. Previous studies indicated that GBS are unable to invade human amniotic epithelial cells (hAECs), which represent the last barrier to the amniotic cavity and fetus. We show that GBS invades hAECs and strains lacking the hemolysin repressor CovR/S accelerate amniotic barrier failure and penetrate chorioamniotic membranes in a hemolysin-dependent manner. Clinical GBS isolates obtained from women in preterm labor are hyperhemolytic and some are associated with covR/S mutations. We demonstrate for the first time that hemolytic and cytolytic activity of GBS is due to the ornithine rhamnolipid pigment and not due to a pore-forming protein toxin. Our studies emphasize the importance of the hemolytic GBS pigment in ascending infection and fetal injury. PMID:23712433

Latest developments on Streptococcus suis: an emerging zoonotic pathogen: part 2.

PubMed

Segura, Mariela; Zheng, Han; de Greeff, Astrid; Gao, George F; Grenier, Daniel; Jiang, Yongqiang; Lu, Chengping; Maskell, Duncan; Oishi, Kazunori; Okura, Masatoshi; Osawa, Ro; Schultsz, Constance; Schwerk, Christian; Sekizaki, Tsutomu; Smith, Hilde; Srimanote, Potjanee; Takamatsu, Daisuke; Tang, Jiaqi; Tenenbaum, Tobias; Tharavichitkul, Prasit; Hoa, Ngo Thi; Valentin-Weigand, Peter; Wells, Jerry M; Wertheim, Heiman; Zhu, Baoli; Xu, Jianguo; Gottschalk, Marcelo

2014-01-01

First International Workshop on Streptococcus suis, Beijing, China, 12-13 August 2013. This second and final chapter of the report on the First International Workshop on Streptococcus suis follows on from Part 1, published in the April 2014, volume 9, issue 4 of Future Microbiology. S. suis is a swine pathogen and a zoonotic agent afflicting people in close contact with infected pigs or pork meat. Although sporadic cases of human infections had been reported worldwide, deadly S. suis outbreaks emerged in Asia. The severity of the disease underscores the lack of knowledge on the virulence and zoonotic evolution of this human-infecting agent. The pathogenesis of the infection, interactions with host cells and new avenues for treatments were among the topics discussed during the First International Workshop on S. suis (China 2013).

Pathogen profile of clinical mastitis in Irish milk-recording herds reveals a complex aetiology.

PubMed

Keane, O M; Budd, K E; Flynn, J; McCoy, F

2013-07-06

Effective mastitis control requires knowledge of the predominant pathogen challenges on the farm. In order to quantify this challenge, the aetiological agents associated with clinical mastitis in 30 milk-recording dairy herds in Ireland over a complete lactation were investigated. Standard bacteriology was performed on 630 pretreatment quarter milk samples, of which 56 per cent were culture-positive, 42 per cent culture-negative and 2 per cent contaminated. Two micro-organisms were isolated from almost 5 per cent of the culture-positive samples. The bacteria isolated were Staphylococcus aureus (23 per cent), Streptococcus uberis (17 per cent), Escherichia coli (9 per cent), Streptococcus species (6 per cent), coagulase-negative Staphylococci (4 per cent) and other species (1 per cent). A wide variety of bacterial species were associated with clinical mastitis, with S aureus the most prevalent pathogen overall, followed by S uberis. However, the bacterial challenges varied widely from farm to farm. In comparison with previous reports, in the present study, the contagious pathogens S aureus and Streptococcus agalactiae were less commonly associated with clinical mastitis, whereas, the environmental pathogens S uberis and E coli were found more commonly associated with clinical mastitis. While S aureus remains the pathogen most commonly associated with intramammary infection in these herds, environmental pathogens, such as S uberis and E coli also present a considerable challenge.

[Analysis of pathogenic bacteria and drug resistance in neonatal purulent meningitis].

PubMed

Zhu, Minli; Hu, Qianhong; Mai, Jingyun; Lin, Zhenlang

2015-01-01

To study the clinical characteristics, pathogenic bacteria, and antibiotics resistance of neonatal purulent meningitis in order to provide the guide for early diagnosis and appropriate treatment. A retrospective review was performed and a total of 112 cases of neonatal purulent meningitis (male 64, female 58) were identified in the neonatal intensive care unit of Yuying Children's Hospital of Wenzhou Medical University seen from January 1, 2004 to December 31, 2013. The clinical information including pathogenic bacterial distribution, drug sensitivity, head imageology and therapeutic outcome were analyzed. Numeration data were shown in ratio and chi square test was applied for group comparison. Among 112 cases, 46 were admitted from 2004 to 2008 and 66 from 2009 to 2013, 23 patients were preterm and 89 were term, 20 were early onset (occurring within 3 days of life) and 92 were late onset meningitis (occurring after 3 days of life). In 62 (55.4%) cases the pathogens were Gram-positive bacteria and in 50 (44.6%) were Gram-negative bacteria. The five most frequently isolated pathogens were Escherichia coli (32 cases, 28.6%), coagulase-negative staphylococcus (CNS, 20 cases, 17.9%), Streptococcus (18 cases, 16.1%, Streptococcus agalactiae 15 cases), Enterococci (13 cases, 11.6%), Staphylococcus aureus (9 cases, 8.0%). Comparison of pathogenic bacterial distribution between 2004-2008 and 2009-2013 showed that Gram-positive bacteria accounted for more than 50% in both period. Escherichia coli was the most common bacterium, followed by Streptococcus in last five years which was higher than the first five years (22.7% (15/66) vs. 6.5% (3/46), χ(2) = 5.278, P < 0.05). Klebsiella pneumoniae was more common isolate in preterm infants than in term infants (13.0% (3/23) vs. 1.1% (1/89), χ(2) = 7.540, P < 0.05). Streptococcus (most were Streptococcus agalactiae) was the most common bacteria in early onset meningitis and higher than those in late onset meningitis (35.0% (7

Cytosolic Access of Intracellular Bacterial Pathogens: The Shigella Paradigm.

PubMed

Mellouk, Nora; Enninga, Jost

2016-01-01

Shigella is a Gram-negative bacterial pathogen, which causes bacillary dysentery in humans. A crucial step of Shigella infection is its invasion of epithelial cells. Using a type III secretion system, Shigella injects several bacterial effectors ultimately leading to bacterial internalization within a vacuole. Then, Shigella escapes rapidly from the vacuole, it replicates within the cytosol and spreads from cell-to-cell. The molecular mechanism of vacuolar rupture used by Shigella has been studied in some detail during the recent years and new paradigms are emerging about the underlying molecular events. For decades, bacterial effector proteins were portrayed as main actors inducing vacuolar rupture. This includes the effector/translocators IpaB and IpaC. More recently, this has been challenged and an implication of the host cell in the process of vacuolar rupture has been put forward. This includes the bacterial subversion of host trafficking regulators, such as the Rab GTPase Rab11. The involvement of the host in determining bacterial vacuolar integrity has also been found for other bacterial pathogens, particularly for Salmonella. Here, we will discuss our current view of host factor and pathogen effector implications during Shigella vacuolar rupture and the steps leading to it.

Parasitism enhances susceptibility to bacterial infection in tilapia

USDA-ARS?s Scientific Manuscript database

Gyrodactylus is a small elongate monogenetic parasite that mainly lives on the skin and gills of freshwater fish. Gyrodactylus causes mechanical injuries on fish epithelium that can lead to fish mortality under crowded conditions. Streptococcus iniae is a severe bacterial pathogen and the economic l...

Comparative genome analysis of two Streptococcus phocae subspecies provides novel insights into pathogenicity.

PubMed

Bethke, J; Avendaño-Herrera, R

2017-02-01

Streptococcus phocae is a beta-hemolytic, Gram-positive bacterium that was first isolated in Norway from clinical specimens of harbor seal (Phoca vitulina) affected by pneumonia or respiratory infection, and in 2005, this bacterium was identified from disease outbreaks at an Atlantic salmon farm. A recent comparative polyphasic study reclassified Streptococcus phocae as subsp. phocae and subsp. salmonis, and there are currently two S. phocae NCBI sequencing projects for the type strains ATCC 51973 T and C-4 T . The present study compared these genome sequences to determine shared properties between the pathogenic mammalian and fish S. phocae subspecies. Both subspecies presented genomic islands, prophages, CRISPRs, and multiple gene activator and RofA regulator regions that could play key roles in the pathogenesis of streptococcal species. Likewise, proteins possibly influencing immune system evasion and virulence strategies were identified in both genomes, including Streptokinases, Streptolysin S, IgG endopeptidase, Fibronectin binding proteins, Daunorubicin, and Penicillin resistance proteins. Comparative differences in phage, non-phage, and genomic island sequences may form the genetic basis for the virulence, pathogenicity, and ability of S. phocae subsp. salmonis to infect and cause disease in Atlantic salmon, in contrast to S. phocae subsp. phocae. This comparative genomic study between two S. phocae subsp. provides novel insights into virulence factors and pathogenicity, offering important information that will facilitate the development of preventive and treatment measures against this pathogen. Copyright © 2016 Elsevier B.V. All rights reserved.

[Septic arthritis caused by Streptococcus suis].

PubMed

Hedegaard, Sofie Sommer; Zaccarin, Matthias; Lindberg, Jens

2013-05-27

Streptococcus suis is a global endemic swine pathogen. S. suis can cause meningitis, endocarditis and severe sepsis in humans, who are exposed to swine. Human infection with S. suis was first reported in 1968, since then, human infections have been sporadic although an outbreak in China counted 215 cases. In a rare case of disseminated arthritis we found that correct clinical diagnosis was difficult due to unspecific symptomatology and slow growing bacterial culture. However, conducting thorough examinations is crucial, and if treated correctly the outcome is favourable.

Cytosolic Access of Intracellular Bacterial Pathogens: The Shigella Paradigm

PubMed Central

Mellouk, Nora; Enninga, Jost

2016-01-01

Shigella is a Gram-negative bacterial pathogen, which causes bacillary dysentery in humans. A crucial step of Shigella infection is its invasion of epithelial cells. Using a type III secretion system, Shigella injects several bacterial effectors ultimately leading to bacterial internalization within a vacuole. Then, Shigella escapes rapidly from the vacuole, it replicates within the cytosol and spreads from cell-to-cell. The molecular mechanism of vacuolar rupture used by Shigella has been studied in some detail during the recent years and new paradigms are emerging about the underlying molecular events. For decades, bacterial effector proteins were portrayed as main actors inducing vacuolar rupture. This includes the effector/translocators IpaB and IpaC. More recently, this has been challenged and an implication of the host cell in the process of vacuolar rupture has been put forward. This includes the bacterial subversion of host trafficking regulators, such as the Rab GTPase Rab11. The involvement of the host in determining bacterial vacuolar integrity has also been found for other bacterial pathogens, particularly for Salmonella. Here, we will discuss our current view of host factor and pathogen effector implications during Shigella vacuolar rupture and the steps leading to it. PMID:27092296

Acanthamoeba castellanii interactions with Streptococcus pneumoniae and Streptococcus pyogenes.

PubMed

Siddiqui, Ruqaiyyah; Yee Ong, Timothy Yu; Jung, Suk Yul; Khan, Naveed Ahmed

2017-12-01

Among the genus Streptococcus, S. pyogenes and S. pneumoniae are the major causes of pharyngitis, impetigo, pneumonia and meningitis in humans. Streptococcus spp. are facultative anaerobes that are nutritionally fastidious, yet survive in the environment and target the predisposed population. Antibacterial disinfectants have been partially effective only, indicating the need for novel preventative measures and to understand mechanisms of bacterial resistance. Acanthamoeba is a free-living protist that is known to harbour microbial pathogens, provide shelter, and assist in their transmission to susceptible population. The overall aim of this study was to determine whether S. pyogenes and S. pneumoniae can interact with A. castellanii by associating, invading, and surviving inside trophozoites and cysts. It was observed that both S. pyogenes and S. pneumoniae were able to associate as well as invade and/or taken up by the phagocytic A. castellanii trophozoite. Notably, S. pyogenes and S. pneumoniae survived the encystation process, avoided phagocytosis, multiplied, and exhibited higher recovery from the mature cysts, compared with the trophozoite stage (approximately 2 bacteria per amoebae ratio for cyst stage versus 0.02 bacteria per amoeba ration for trophozoite stage). As Acanthamoeba cysts are resilient and can disperse through the air, A. castellanii can act as a vector in providing shelter, facilitating growth and possibly genetic exchanges. In addition, these interactions may contribute to S. pyogenes and S. pneumoniae survival in harsh environments, and transmission to susceptible population and possibly affecting their virulence. Future studies will determine the molecular mechanisms associated with Acanthamoeba interactions with Streptococcus and the evolution of pathogenic bacteria and in turn expedite the discovery of novel therapeutic and/or preventative measures. Copyright © 2017 Elsevier Inc. All rights reserved.

Molecular mechanisms of cell-cell spread of intracellular bacterial pathogens.

PubMed

Ireton, Keith

2013-07-17

Several bacterial pathogens, including Listeria monocytogenes, Shigella flexneri and Rickettsia spp., have evolved mechanisms to actively spread within human tissues. Spreading is initiated by the pathogen-induced recruitment of host filamentous (F)-actin. F-actin forms a tail behind the microbe, propelling it through the cytoplasm. The motile pathogen then encounters the host plasma membrane, forming a bacterium-containing protrusion that is engulfed by an adjacent cell. Over the past two decades, much progress has been made in elucidating mechanisms of F-actin tail formation. Listeria and Shigella produce tails of branched actin filaments by subverting the host Arp2/3 complex. By contrast, Rickettsia forms tails with linear actin filaments through a bacterial mimic of eukaryotic formins. Compared with F-actin tail formation, mechanisms controlling bacterial protrusions are less well understood. However, recent findings have highlighted the importance of pathogen manipulation of host cell-cell junctions in spread. Listeria produces a soluble protein that enhances bacterial protrusions by perturbing tight junctions. Shigella protrusions are engulfed through a clathrin-mediated pathway at 'tricellular junctions'--specialized membrane regions at the intersection of three epithelial cells. This review summarizes key past findings in pathogen spread, and focuses on recent developments in actin-based motility and the formation and internalization of bacterial protrusions.

Recurrent bacterial meningitis by three different pathogens in an isolated asplenic child.

PubMed

Uchida, Yoshiko; Matsubara, Kousaku; Wada, Tamaki; Oishi, Kazunori; Morio, Tomohiro; Takada, Hidetoshi; Iwata, Aya; Yura, Kazuo; Kamimura, Katsunori; Nigami, Hiroyuki; Fukaya, Takashi

2012-08-01

Isolated congenital asplenia (ICA) is a rare condition at risk for overwhelming infection. When complicated by invasive infection, the mortality remains high, at greater than 60%. We describe a girl with ICA who developed recurrent meningitis by three different pathogens. The first, meningitis by Escherichia coli, occurred 4 days after premature birth. The other two pathogens were serotype 6B Streptococcus pneumoniae and Haemophilus influenzae type b (Hib), at 18 and 25 months of age, respectively. The patient was successfully treated with prompt antimicrobial therapy in all episodes. Serum anti-polyribosylribitol phosphate (PRP) and anti-6B-type pneumococcal antibodies were below the levels for protective activity after natural infections. Although anti-PRP antibody was significantly increased after Hib vaccination, two (6B and 19F) of seven serotype-specific pneumococcal antibodies were not elevated to protective levels after the second 7-valent pneumococcal conjugate vaccine (PCV7). We, therefore, added a third PCV7. To our knowledge, this is the first neonatal ICA patient with invasive infection and the first case of bacterial meningitis occurring three times. Our findings indicate that monitoring of immune responses after natural infections and vaccinations, and reevaluations of vaccine schedule, are important for ICA patients to prevent subsequent invasive infections.

A Critical Role of Zinc Importer AdcABC in Group A Streptococcus-Host Interactions During Infection and Its Implications for Vaccine Development.

PubMed

Makthal, Nishanth; Nguyen, Kimberly; Do, Hackwon; Gavagan, Maire; Chandrangsu, Pete; Helmann, John D; Olsen, Randall J; Kumaraswami, Muthiah

2017-07-01

Bacterial pathogens must overcome host immune mechanisms to acquire micronutrients for successful replication and infection. Streptococcus pyogenes, also known as group A streptococcus (GAS), is a human pathogen that causes a variety of clinical manifestations, and disease prevention is hampered by lack of a human GAS vaccine. Herein, we report that the mammalian host recruits calprotectin (CP) to GAS infection sites and retards bacterial growth by zinc limitation. However, a GAS-encoded zinc importer and a nuanced zinc sensor aid bacterial defense against CP-mediated growth inhibition and contribute to GAS virulence. Immunization of mice with the extracellular component of the zinc importer confers protection against systemic GAS challenge. Together, we identified a key early stage host-GAS interaction and translated that knowledge into a novel vaccine strategy against GAS infection. Furthermore, we provided evidence that a similar struggle for zinc may occur during other streptococcal infections, which raises the possibility of a broad-spectrum prophylactic strategy against multiple streptococcal pathogens. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

Loofah sponges as reservoirs and vehicles in the transmission of potentially pathogenic bacterial species to human skin.

PubMed Central

Bottone, E J; Perez, A A; Oeser, J L

1994-01-01

Loofah sponges are natural products used as exfoliative beauty aids. As a consequence of tracing a case of Pseudomonas aeruginosa folliculitis to a contaminated loofah sponge, we assessed the role of loofah sponges in supporting the growth of a wide variety of bacterial species. Our data show growth enhancement of sterile loofah fragments for numerous gram-negative (Pseudomonas, Xanthomonas, and Klebsiella) and gram-positive (Enterococcus and group B Streptococcus) species of human and environmental origin. Furthermore, hydrated new, unused loofah sponges undergo a shift in bacterial flora from sparse colonies of Bacillus spp. and Staphylococcus epidermidis to a predominantly gram-negative flora. The growth-promoting potential of loofah sponges (and other exfoliatives) can be further augmented by desquamated epithelial cells entrapped in the loofah fibrous matrix. Therefore, as loofah sponges (and other exfoliatives) can serve as a reservoir and a vehicle for the transmission of potentially pathogenic species to the human skin, we recommend their decontamination with hypochlorite (10%) bleach at regular intervals. Images PMID:8150959

Loofah sponges as reservoirs and vehicles in the transmission of potentially pathogenic bacterial species to human skin.

PubMed

Bottone, E J; Perez, A A; Oeser, J L

1994-02-01

Loofah sponges are natural products used as exfoliative beauty aids. As a consequence of tracing a case of Pseudomonas aeruginosa folliculitis to a contaminated loofah sponge, we assessed the role of loofah sponges in supporting the growth of a wide variety of bacterial species. Our data show growth enhancement of sterile loofah fragments for numerous gram-negative (Pseudomonas, Xanthomonas, and Klebsiella) and gram-positive (Enterococcus and group B Streptococcus) species of human and environmental origin. Furthermore, hydrated new, unused loofah sponges undergo a shift in bacterial flora from sparse colonies of Bacillus spp. and Staphylococcus epidermidis to a predominantly gram-negative flora. The growth-promoting potential of loofah sponges (and other exfoliatives) can be further augmented by desquamated epithelial cells entrapped in the loofah fibrous matrix. Therefore, as loofah sponges (and other exfoliatives) can serve as a reservoir and a vehicle for the transmission of potentially pathogenic species to the human skin, we recommend their decontamination with hypochlorite (10%) bleach at regular intervals.

The Effect of Antibiotic Exposure and Specimen Volume on the Detection of Bacterial Pathogens in Children With Pneumonia.

PubMed

Driscoll, Amanda J; Deloria Knoll, Maria; Hammitt, Laura L; Baggett, Henry C; Brooks, W Abdullah; Feikin, Daniel R; Kotloff, Karen L; Levine, Orin S; Madhi, Shabir A; O'Brien, Katherine L; Scott, J Anthony G; Thea, Donald M; Howie, Stephen R C; Adrian, Peter V; Ahmed, Dilruba; DeLuca, Andrea N; Ebruke, Bernard E; Gitahi, Caroline; Higdon, Melissa M; Kaewpan, Anek; Karani, Angela; Karron, Ruth A; Mazumder, Razib; McLellan, Jessica; Moore, David P; Mwananyanda, Lawrence; Park, Daniel E; Prosperi, Christine; Rhodes, Julia; Saifullah, Md; Seidenberg, Phil; Sow, Samba O; Tamboura, Boubou; Zeger, Scott L; Murdoch, David R

2017-06-15

Antibiotic exposure and specimen volume are known to affect pathogen detection by culture. Here we assess their effects on bacterial pathogen detection by both culture and polymerase chain reaction (PCR) in children. PERCH (Pneumonia Etiology Research for Child Health) is a case-control study of pneumonia in children aged 1-59 months investigating pathogens in blood, nasopharyngeal/oropharyngeal (NP/OP) swabs, and induced sputum by culture and PCR. Antibiotic exposure was ascertained by serum bioassay, and for cases, by a record of antibiotic treatment prior to specimen collection. Inoculated blood culture bottles were weighed to estimate volume. Antibiotic exposure ranged by specimen type from 43.5% to 81.7% in 4223 cases and was detected in 2.3% of 4863 controls. Antibiotics were associated with a 45% reduction in blood culture yield and approximately 20% reduction in yield from induced sputum culture. Reduction in yield of Streptococcus pneumoniae from NP culture was approximately 30% in cases and approximately 32% in controls. Several bacteria had significant but marginal reductions (by 5%-7%) in detection by PCR in NP/OP swabs from both cases and controls, with the exception of S. pneumoniae in exposed controls, which was detected 25% less frequently compared to nonexposed controls. Bacterial detection in induced sputum by PCR decreased 7% for exposed compared to nonexposed cases. For every additional 1 mL of blood culture specimen collected, microbial yield increased 0.51% (95% confidence interval, 0.47%-0.54%), from 2% when volume was ≤1 mL to approximately 6% for ≥3 mL. Antibiotic exposure and blood culture volume affect detection of bacterial pathogens in children with pneumonia and should be accounted for in studies of etiology and in clinical management. © The Author 2017. Published by Oxford University Press for the Infectious Diseases Society of America.

Insight into the molecular basis of pathogen abundance: group A Streptococcus inhibitor of complement inhibits bacterial adherence and internalization into human cells.

PubMed

Hoe, Nancy P; Ireland, Robin M; DeLeo, Frank R; Gowen, Brian B; Dorward, David W; Voyich, Jovanka M; Liu, Mengyao; Burns, Eugene H; Culnan, Derek M; Bretscher, Anthony; Musser, James M

2002-05-28

Streptococcal inhibitor of complement (Sic) is a secreted protein made predominantly by serotype M1 Group A Streptococcus (GAS), which contributes to persistence in the mammalian upper respiratory tract and epidemics of human disease. Unexpectedly, an isogenic sic-negative mutant adhered to human epithelial cells significantly better than the wild-type parental strain. Purified Sic inhibited the adherence of a sic negative serotype M1 mutant and of non-Sic-producing GAS strains to human epithelial cells. Sic was rapidly internalized by human epithelial cells, inducing cell flattening and loss of microvilli. Ezrin and moesin, human proteins that functionally link the cytoskeleton to the plasma membrane, were identified as Sic-binding proteins by affinity chromatography and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry analysis. Sic colocalized with ezrin inside epithelial cells and bound to the F-actin-binding site region located in the carboxyl terminus of ezrin and moesin. Synthetic peptides corresponding to two regions of Sic had GAS adherence-inhibitory activity equivalent to mature Sic and inhibited binding of Sic to ezrin. In addition, the sic mutant was phagocytosed and killed by human polymorphonuclear leukocytes significantly better than the wild-type strain, and Sic colocalized with ezrin in discrete regions of polymorphonuclear leukocytes. The data suggest that binding of Sic to ezrin alters cellular processes critical for efficient GAS contact, internalization, and killing. Sic enhances bacterial survival by enabling the pathogen to avoid the intracellular environment. This process contributes to the abundance of M1 GAS in human infections and their ability to cause epidemics.

Zinc disrupts central carbon metabolism and capsule biosynthesis in Streptococcus pyogenes.

PubMed

Ong, Cheryl-lynn Y; Walker, Mark J; McEwan, Alastair G

2015-06-01

Neutrophils release free zinc to eliminate the phagocytosed bacterial pathogen Streptococcus pyogenes (Group A Streptococcus; GAS). In this study, we investigated the mechanisms underpinning zinc toxicity towards this human pathogen, responsible for diseases ranging from pharyngitis and impetigo, to severe invasive infections. Using the globally-disseminated M1T1 GAS strain, we demonstrate that zinc stress impairs glucose metabolism through the inhibition of the glycolytic enzymes phosphofructokinase and glyceraldehyde-3-phosphate dehydrogenase. In the presence of zinc, a metabolic shift to the tagatose-6-phosphate pathway allows conversion of D-galactose to dihydroxyacetone phosphate and glyceraldehyde phosphate, partially bypassing impaired glycolytic enzymes to generate pyruvate. Additionally, zinc inhibition of phosphoglucomutase results in decreased capsule biosynthesis. These data indicate that zinc exerts it toxicity via mechanisms that inhibit both GAS central carbon metabolism and virulence pathways.

Zinc disrupts central carbon metabolism and capsule biosynthesis in Streptococcus pyogenes

PubMed Central

Ong, Cheryl-lynn Y.; Walker, Mark J.; McEwan, Alastair G.

2015-01-01

Neutrophils release free zinc to eliminate the phagocytosed bacterial pathogen Streptococcus pyogenes (Group A Streptococcus; GAS). In this study, we investigated the mechanisms underpinning zinc toxicity towards this human pathogen, responsible for diseases ranging from pharyngitis and impetigo, to severe invasive infections. Using the globally-disseminated M1T1 GAS strain, we demonstrate that zinc stress impairs glucose metabolism through the inhibition of the glycolytic enzymes phosphofructokinase and glyceraldehyde-3-phosphate dehydrogenase. In the presence of zinc, a metabolic shift to the tagatose-6-phosphate pathway allows conversion of D-galactose to dihydroxyacetone phosphate and glyceraldehyde phosphate, partially bypassing impaired glycolytic enzymes to generate pyruvate. Additionally, zinc inhibition of phosphoglucomutase results in decreased capsule biosynthesis. These data indicate that zinc exerts it toxicity via mechanisms that inhibit both GAS central carbon metabolism and virulence pathways. PMID:26028191

Pathogen detection in milk samples by ligation detection reaction-mediated universal array method.

PubMed

Cremonesi, P; Pisoni, G; Severgnini, M; Consolandi, C; Moroni, P; Raschetti, M; Castiglioni, B

2009-07-01

This paper describes a new DNA chip, based on the use of a ligation detection reaction coupled to a universal array, developed to detect and analyze, directly from milk samples, microbial pathogens known to cause bovine, ovine, and caprine mastitis or to be responsible for foodborne intoxication or infection, or both. Probes were designed for the identification of 15 different bacterial groups: Staphylococcus aureus, Streptococcus agalactiae, nonaureus staphylococci, Streptococcus bovis, Streptococcus equi, Streptococcus canis, Streptococcus dysgalactiae, Streptococcus parauberis, Streptococcus uberis, Streptococcus pyogenes, Mycoplasma spp., Salmonella spp., Bacillus spp., Campylobacter spp., and Escherichia coli and related species. These groups were identified based on the 16S rRNA gene. For microarray validation, 22 strains from the American Type Culture Collection or other culture collections and 50 milk samples were tested. The results demonstrated high specificity, with sensitivity as low as 6 fmol. Moreover, the ligation detection reaction-universal array assay allowed for the identification of Mycoplasma spp. in a few hours, avoiding the long incubation times of traditional microbiological identification methods. The universal array described here is a versatile tool able to identify milk pathogens efficiently and rapidly.

Evaluation of an Internally Controlled Multiplex Tth Endonuclease Cleavage Loop-Mediated Isothermal Amplification (TEC-LAMP) Assay for the Detection of Bacterial Meningitis Pathogens.

PubMed

Higgins, Owen; Clancy, Eoin; Cormican, Martin; Boo, Teck Wee; Cunney, Robert; Smith, Terry J

2018-02-09

Bacterial meningitis infection is a leading global health concern for which rapid and accurate diagnosis is essential to reduce associated morbidity and mortality. Loop-mediated isothermal amplification (LAMP) offers an effective low-cost diagnostic approach; however, multiplex LAMP is difficult to achieve, limiting its application. We have developed novel real-time multiplex LAMP technology, TEC-LAMP, using Tth endonuclease IV and a unique LAMP primer/probe. This study evaluates the analytical specificity, limit of detection (LOD) and clinical application of an internally controlled multiplex TEC-LAMP assay for detection of leading bacterial meningitis pathogens: Streptococcus pneumoniae , Neisseria meningitidis and Haemophilus influenzae . Analytical specificities were established by testing 168 bacterial strains, and LODs were determined using Probit analysis. The TEC-LAMP assay was 100% specific, with LODs for S. pneumoniae , N. meningitidis and H. influenzae of 39.5, 17.3 and 25.9 genome copies per reaction, respectively. Clinical performance was evaluated by testing 65 archived PCR-positive samples. Compared to singleplex real-time PCR, the multiplex TEC-LAMP assay demonstrated diagnostic sensitivity and specificity of 92.3% and 100%, respectively. This is the first report of a single-tube internally controlled multiplex LAMP assay for bacterial meningitis pathogen detection, and the first report of Tth endonuclease IV incorporation into nucleic acid amplification diagnostic technology.

Characterization of a Streptococcus suis tet(O/W/32/O)-carrying element transferable to major streptococcal pathogens.

PubMed

Palmieri, Claudio; Magi, Gloria; Mingoia, Marina; Bagnarelli, Patrizia; Ripa, Sandro; Varaldo, Pietro E; Facinelli, Bruna

2012-09-01

Mosaic tetracycline resistance determinants are a recently discovered class of hybrids of ribosomal protection tet genes. They may show different patterns of mosaicism, but their final size has remained unaltered. Initially thought to be confined to a small group of anaerobic bacteria, mosaic tet genes were then found to be widespread. In the genus Streptococcus, a mosaic tet gene [tet(O/W/32/O)] was first discovered in Streptococcus suis, an emerging drug-resistant pig and human pathogen. In this study, we report the molecular characterization of a tet(O/W/32/O) gene-carrying mobile element from an S. suis isolate. tet(O/W/32/O) was detected, in tandem with tet(40), in a circular 14,741-bp genetic element (39.1% G+C; 17 open reading frames [ORFs] identified). The novel element, which we designated 15K, also carried the macrolide resistance determinant erm(B) and an aminoglycoside resistance four-gene cluster including aadE (streptomycin) and aphA (kanamycin). 15K appeared to be an unstable genetic element that, in the absence of recombinases, is capable of undergoing spontaneous excision under standard growth conditions. In the integrated form, 15K was found inside a 54,879-bp integrative and conjugative element (ICE) (50.5% G+C; 55 ORFs), which we designated ICESsu32457. An ∼1.3-kb segment that apparently served as the att site for excision of the unstable 15K element was identified. The novel ICE was transferable at high frequency to recipients from pathogenic Streptococcus species (S. suis, Streptococcus pyogenes, Streptococcus pneumoniae, and Streptococcus agalactiae), suggesting that the multiresistance 15K element can successfully spread within streptococcal populations.

Development of primer sets for loop-mediated isothermal amplification that enables rapid and specific detection of Streptococcus dysgalactiae, Streptococcus uberis and Streptococcus agalactiae

USDA-ARS?s Scientific Manuscript database

Streptococcus dysgalactiae, Streptococcus uberis and Streptococcus agalactiae are the three main pathogens causing bovine mastitis, with great losses to the dairy industry. Rapid and specific loop-mediated isothermal amplification methods (LAMP) for identification and differentiation of these three ...

Polymers for binding of the gram-positive oral pathogen Streptococcus mutans

PubMed Central

Magennis, Eugene P.; Francini, Nora; Mastrotto, Francesca; Catania, Rosa; Redhead, Martin; Fernandez-Trillo, Francisco; Bradshaw, David; Churchley, David; Winzer, Klaus; Alexander, Cameron

2017-01-01

Streptococcus mutans is the most significant pathogenic bacterium implicated in the formation of dental caries and, both directly and indirectly, has been associated with severe conditions such as multiple sclerosis, cerebrovascular and peripheral artery disease. Polymers able to selectively bind S. mutans and/or inhibit its adhesion to oral tissue in a non-lethal manner would offer possibilities for addressing pathogenicity without selecting for populations resistant against bactericidal agents. In the present work two libraries of 2-(dimethylamino)ethyl methacrylate (pDMAEMA)-based polymers were synthesized with various proportions of either N,N,N-trimethylethanaminium cationic- or sulfobetaine zwitterionic groups. These copolymers where initially tested as potential macromolecular ligands for S. mutans NCTC 10449, whilst Escherichia coli MG1655 was used as Gram-negative control bacteria. pDMAEMA-derived materials with high proportions of zwitterionic repeating units were found to be selective for S. mutans, in both isolated and S. mutans–E. coli mixed bacterial cultures. Fully sulfobetainized pDMAEMA was subsequently found to bind/cluster preferentially Gram-positive S. mutans and S. aureus compared to Gram negative E. coli and V. harveyi. A key initial stage of S. mutans pathogenesis involves a lectin-mediated adhesion to the tooth surface, thus the range of potential macromolecular ligands was further expanded by investigating two glycopolymers bearing α-mannopyranoside and β-galactopyranoside pendant units. Results with these polymers indicated that preferential binding to either S. mutans or E. coli can be obtained by modulating the glycosylation pattern of the chosen multivalent ligands without incurring unacceptable cytotoxicity in a model gastrointestinal cell line. Overall, our results allowed to identify a structure–property relationship for the potential antimicrobial polymers investigated, and suggest that preferential binding to Gram-positive S

Bacterial Superantigens Promote Acute Nasopharyngeal Infection by Streptococcus pyogenes in a Human MHC Class II-Dependent Manner

PubMed Central

Kasper, Katherine J.; Zeppa, Joseph J.; Wakabayashi, Adrienne T.; Xu, Stacey X.; Mazzuca, Delfina M.; Welch, Ian; Baroja, Miren L.; Kotb, Malak; Cairns, Ewa; Cleary, P. Patrick; Haeryfar, S. M. Mansour; McCormick, John K.

2014-01-01

Establishing the genetic determinants of niche adaptation by microbial pathogens to specific hosts is important for the management and control of infectious disease. Streptococcus pyogenes is a globally prominent human-specific bacterial pathogen that secretes superantigens (SAgs) as ‘trademark’ virulence factors. SAgs function to force the activation of T lymphocytes through direct binding to lateral surfaces of T cell receptors and class II major histocompatibility complex (MHC-II) molecules. S. pyogenes invariably encodes multiple SAgs, often within putative mobile genetic elements, and although SAgs are documented virulence factors for diseases such as scarlet fever and the streptococcal toxic shock syndrome (STSS), how these exotoxins contribute to the fitness and evolution of S. pyogenes is unknown. Here we show that acute infection in the nasopharynx is dependent upon both bacterial SAgs and host MHC-II molecules. S. pyogenes was rapidly cleared from the nasal cavity of wild-type C57BL/6 (B6) mice, whereas infection was enhanced up to ∼10,000-fold in B6 mice that express human MHC-II. This phenotype required the SpeA superantigen, and vaccination with an MHC –II binding mutant toxoid of SpeA dramatically inhibited infection. Our findings indicate that streptococcal SAgs are critical for the establishment of nasopharyngeal infection, thus providing an explanation as to why S. pyogenes produces these potent toxins. This work also highlights that SAg redundancy exists to avoid host anti-SAg humoral immune responses and to potentially overcome host MHC-II polymorphisms. PMID:24875883

Assessment of bacterial contamination of lipstick using pyrosequencing.

PubMed

Lee, So Y; Lee, Si Y

As soon as they are exposed to the environment, cosmetics become contaminated with microorganisms, and this contamination accumulates with increased use. In this study, we employed pyrosequencing to investigate the diversity of bacteria found on lipstick. Bacterial DNA was extracted from 20 lipstick samples and mixed in equal ratios for pyrosequencing analysis. As a result, 105 bacterial genera were detected, four of which ( Leifsonia , Methylobacterium , Streptococcus , and Haemophilus ) were predominant in 92% of the 19,863 total sequence reads. Potentially pathogenic genera such as Staphylococcus , Pseudomonas , Escherichia , Salmonella , Corynebacterium , Mycobacterium , and Neisseria accounted for 27.6% of the 105 genera. The most commonly identified oral bacteria belonged to the Streptococcus genus, although other oral genera such as Actinomyces , Fusobacterium , Porphyromonas , and Lactobacillus were also detected.

Emerging bacterial pathogens: the past and beyond.

PubMed

Vouga, M; Greub, G

2016-01-01

Since the 1950s, medical communities have been facing with emerging and reemerging infectious diseases, and emerging pathogens are now considered to be a major microbiologic public health threat. In this review, we focus on bacterial emerging diseases and explore factors involved in their emergence as well as future challenges. We identified 26 major emerging and reemerging infectious diseases of bacterial origin; most of them originated either from an animal and are considered to be zoonoses or from water sources. Major contributing factors in the emergence of these bacterial infections are: (1) development of new diagnostic tools, such as improvements in culture methods, development of molecular techniques and implementation of mass spectrometry in microbiology; (2) increase in human exposure to bacterial pathogens as a result of sociodemographic and environmental changes; and (3) emergence of more virulent bacterial strains and opportunistic infections, especially affecting immunocompromised populations. A precise definition of their implications in human disease is challenging and requires the comprehensive integration of microbiological, clinical and epidemiologic aspects as well as the use of experimental models. It is now urgent to allocate financial resources to gather international data to provide a better understanding of the clinical relevance of these waterborne and zoonotic emerging diseases. Copyright © 2015. Published by Elsevier Ltd.

Plant-bacterial pathogen interactions mediated by type III effectors.

PubMed

Feng, Feng; Zhou, Jian-Min

2012-08-01

Effectors secreted by the bacterial type III system play a central role in the interaction between Gram-negative bacterial pathogens and their host plants. Recent advances in the effector studies have helped cementing several key concepts concerning bacterial pathogenesis, plant immunity, and plant-pathogen co-evolution. Type III effectors use a variety of biochemical mechanisms to target specific host proteins or DNA for pathogenesis. The identifications of their host targets led to the identification of novel components of plant innate immune system. Key modules of plant immune signaling pathways such as immune receptor complexes and MAPK cascades have emerged as a major battle ground for host-pathogen adaptation. These modules are attacked by multiple type III effectors, and some components of these modules have evolved to actively sense the effectors and trigger immunity. Copyright © 2012 Elsevier Ltd. All rights reserved.

The RFK catalytic cycle of the pathogen Streptococcus pneumoniae shows species-specific features in prokaryotic FMN synthesis.

PubMed

Sebastián, María; Velázquez-Campoy, Adrián; Medina, Milagros

2018-12-01

Emergence of multidrug-resistant bacteria forces us to explore new therapeutic strategies, and proteins involved in key metabolic pathways are promising anti-bacterial targets. Bifunctional flavin-adenine dinucleotide (FAD) synthetases (FADS) are prokaryotic enzymes that synthesise the flavin mononucleotide (FMN) and FAD cofactors. The FADS from the human pathogen Streptococcus pneumoniae (SpnFADS)-causative agent of pneumonia in humans - shows relevant catalytic dissimilarities compared to other FADSs. Here, by integrating thermodynamic and kinetic data, we present a global description of the riboflavin kinase activity of SpnFADS, as well as of the inhibition mechanisms regulating this activity. Our data shed light on biophysical determinants that modulate species-specific conformational changes leading to catalytically competent conformations, as well as binding rates and affinities of substrates versus products. This knowledge paves the way for the development of tools - that taking advantage of the regulatory dissimilarities during FMN biosynthesis in different species - might be used in the discovery of specific anti-pneumococcal drugs.

Characterization of a Multipeptide Lantibiotic Locus in Streptococcus pneumoniae.

PubMed

Maricic, Natalie; Anderson, Erica S; Opipari, AnneMarie E; Yu, Emily A; Dawid, Suzanne

2016-01-26

Bacterial communities are established through a combination of cooperative and antagonistic interactions between the inhabitants. Competitive interactions often involve the production of antimicrobial substances, including bacteriocins, which are small antimicrobial peptides that target other community members. Despite the nearly ubiquitous presence of bacteriocin-encoding loci, inhibitory activity has been attributed to only a small fraction of gene clusters. In this study, we characterized a novel locus (the pld locus) in the pathogen Streptococcus pneumoniae that drives the production of a bacteriocin called pneumolancidin, which has broad antimicrobial activity. The locus encodes an unusual tandem array of four inhibitory peptides, three of which are absolutely required for antibacterial activity. The three peptide sequences are similar but appear to play distinct roles in regulation and inhibition. A modification enzyme typically found in loci encoding a class of highly modified bacteriocins called lantibiotics was required for inhibitory activity. The production of pneumolancidin is controlled by a two-component regulatory system that is activated by the accumulation of modified peptides. The locus is located on a mobile element that has been found in many pneumococcal lineages, although not all elements carry the pld genes. Intriguingly, a minimal region containing only the genes required for pneumolancidin immunity was found in several Streptococcus mitis strains. The pneumolancidin-producing strain can inhibit nearly all pneumococci tested to date and provided a competitive advantage in vivo. These peptides not only represent a unique strategy for bacterial competition but also are an important resource to guide the development of new antimicrobials. Successful colonization of a polymicrobial host surface is a prerequisite for the subsequent development of disease for many bacterial pathogens. Bacterial factors that directly inhibit the growth of neighbors

Bacterial pathogens of the bovine respiratory disease complex.

PubMed

Griffin, Dee; Chengappa, M M; Kuszak, Jennifer; McVey, D Scott

2010-07-01

Pneumonia caused by the bacterial pathogens discussed in this article is the most significant cause of morbidity and mortality of the BRDC. Most of these infectious bacteria are not capable of inducing significant disease without the presence of other predisposing environmental factors, physiologic stressors, or concurrent infections. Mannheimia haemolytica is the most common and serious of these bacterial agents and is therefore also the most highly characterized. There are other important bacterial pathogens of BRD, such as Pasteurella multocida, Histophulus somni, and Mycoplasma bovis. Mixed infections with these organisms do occur. These pathogens have unique and common virulence factors but the resulting pneumonic lesions may be similar. Although the amount and quality of research associated with BRD has increased, vaccination and therapeutic practices are not fully successful. A greater understanding of the virulence mechanisms of the infecting bacteria and pathogenesis of pneumonia, as well as the characteristics of the organisms that allow tissue persistence, may lead to improved management, therapeutics, and vaccines. Copyright 2010 Elsevier Inc. All rights reserved.

Bacterial genome engineering and synthetic biology: combating pathogens.

PubMed

Krishnamurthy, Malathy; Moore, Richard T; Rajamani, Sathish; Panchal, Rekha G

2016-11-04

The emergence and prevalence of multidrug resistant (MDR) pathogenic bacteria poses a serious threat to human and animal health globally. Nosocomial infections and common ailments such as pneumonia, wound, urinary tract, and bloodstream infections are becoming more challenging to treat due to the rapid spread of MDR pathogenic bacteria. According to recent reports by the World Health Organization (WHO) and Centers for Disease Control and Prevention (CDC), there is an unprecedented increase in the occurrence of MDR infections worldwide. The rise in these infections has generated an economic strain worldwide, prompting the WHO to endorse a global action plan to improve awareness and understanding of antimicrobial resistance. This health crisis necessitates an immediate action to target the underlying mechanisms of drug resistance in bacteria. The advent of new bacterial genome engineering and synthetic biology (SB) tools is providing promising diagnostic and treatment plans to monitor and treat widespread recalcitrant bacterial infections. Key advances in genetic engineering approaches can successfully aid in targeting and editing pathogenic bacterial genomes for understanding and mitigating drug resistance mechanisms. In this review, we discuss the application of specific genome engineering and SB methods such as recombineering, clustered regularly interspaced short palindromic repeats (CRISPR), and bacterial cell-cell signaling mechanisms for pathogen targeting. The utility of these tools in developing antibacterial strategies such as novel antibiotic production, phage therapy, diagnostics and vaccine production to name a few, are also highlighted. The prevalent use of antibiotics and the spread of MDR bacteria raise the prospect of a post-antibiotic era, which underscores the need for developing novel therapeutics to target MDR pathogens. The development of enabling SB technologies offers promising solutions to deliver safe and effective antibacterial therapies.

Evaluating bacterial pathogen DNA preservation in museum osteological collections

PubMed Central

Barnes, Ian; Thomas, Mark G

2005-01-01

Reports of bacterial pathogen DNA sequences obtained from archaeological bone specimens raise the possibility of greatly improving our understanding of the history of infectious diseases. However, the survival of pathogen DNA over long time periods is poorly characterized, and scepticism remains about the reliability of these data. In order to explore the survival of bacterial pathogen DNA in bone specimens, we analysed samples from 59 eighteenth and twentieth century individuals known to have been infected with either Mycobacterium tuberculosis or Treponema pallidum. No reproducible evidence of surviving pathogen DNA was obtained, despite the use of extraction and PCR-amplification methods determined to be highly sensitive. These data suggest that previous studies need to be interpreted with caution, and we propose that a much greater emphasis is placed on understanding how pathogen DNA survives in archaeological material, and how its presence can be properly verified and used. PMID:16608682

Profile and Fate of Bacterial Pathogens in Sewage Treatment Plants Revealed by High-Throughput Metagenomic Approach.

PubMed

Li, Bing; Ju, Feng; Cai, Lin; Zhang, Tong

2015-09-01

The broad-spectrum profile of bacterial pathogens and their fate in sewage treatment plants (STPs) were investigated using high-throughput sequencing based metagenomic approach. This novel approach could provide a united platform to standardize bacterial pathogen detection and realize direct comparison among different samples. Totally, 113 bacterial pathogen species were detected in eight samples including influent, effluent, activated sludge (AS), biofilm, and anaerobic digestion sludge with the abundances ranging from 0.000095% to 4.89%. Among these 113 bacterial pathogens, 79 species were reported in STPs for the first time. Specially, compared to AS in bulk mixed liquor, more pathogen species and higher total abundance were detected in upper foaming layer of AS. This suggests that the foaming layer of AS might impose more threat to onsite workers and citizens in the surrounding areas of STPs because pathogens in foaming layer are easily transferred into air and cause possible infections. The high removal efficiency (98.0%) of total bacterial pathogens suggests that AS treatment process is effective to remove most bacterial pathogens. Remarkable similarities of bacterial pathogen compositions between influent and human gut indicated that bacterial pathogen profiles in influents could well reflect the average bacterial pathogen communities of urban resident guts within the STP catchment area.

Nationwide surveillance of bacterial respiratory pathogens conducted by the surveillance committee of Japanese Society of Chemotherapy, the Japanese Association for Infectious Diseases, and the Japanese Society for Clinical Microbiology in 2012: General view of the pathogens' antibacterial susceptibility.

PubMed

Yanagihara, Katsunori; Watanabe, Akira; Aoki, Nobuki; Matsumoto, Tetsuya; Yoshida, Masaki; Sato, Junko; Wakamura, Tomotaro; Sunakawa, Keisuke; Kadota, Junichi; Kiyota, Hiroshi; Iwata, Satoshi; Kaku, Mitsuo; Hanaki, Hideaki; Ohsaki, Yoshinobu; Fujiuchi, Satoru; Takahashi, Manabu; Takeuchi, Kenichi; Takeda, Hiroaki; Ikeda, Hideki; Miki, Makoto; Nakanowatari, Susumu; Takahashi, Hiroshi; Utagawa, Mutsuko; Nishiya, Hajime; Kawakami, Sayoko; Morino, Eriko; Takasaki, Jin; Mezaki, Kazuhisa; Chonabayashi, Naohiko; Tanaka, Chie; Sugiura, Hideko; Goto, Hajime; Saraya, Takeshi; Kurai, Daisuke; Katono, Yasuhiro; Inose, Rika; Niki, Yoshihito; Takuma, Takahiro; Kudo, Makoto; Ehara, Shigeru; Sato, Yoshimi; Tsukada, Hiroki; Watabe, Nobuei; Honma, Yasuo; Mikamo, Hiroshige; Yamagishi, Yuka; Nakamura, Atsushi; Ohashi, Minoru; Seki, Masafumi; Hamaguchi, Shigeto; Toyokawa, Masahiro; Fujikawa, Yasunori; Mitsuno, Noriko; Ukimura, Akira; Miyara, Takayuki; Nakamura, Takahito; Mikasa, Keiichi; Kasahara, Kei; Ui, Koji; Fukuda, Saori; Nakamura, Akihiro; Morimura, Mika; Yamashita, Mikio; Takesue, Yoshio; Wada, Yasunao; Sugimoto, Keisuke; Kusano, Nobuchika; Nose, Motoko; Mihara, Eiichirou; Kuwabara, Masao; Doi, Masao; Watanabe, Yaeko; Tokuyasu, Hirokazu; Hino, Satoshi; Negayama, Kiyoshi; Mukae, Hiroshi; Kawanami, Toshinori; Ota, Toshiyuki; Fujita, Masaki; Honda, Junichi; Hiramatsu, Kazufumi; Aoki, Yosuke; Fukuoka, Mami; Magarifuchi, Hiroki; Nagasawa, Zenzo; Kaku, Norihito; Fujita, Jiro; Higa, Futoshi; Tateyama, Masao

2017-09-01

The nationwide surveillance on antimicrobial susceptibility of bacterial respiratory pathogens from the patients in Japan was conducted by Japanese Society of Chemotherapy, Japanese association for infectious diseases and Japanese society for Clinical Microbiology in 2012. The isolates were collected from clinical specimens obtained from well-diagnosed adult patients with respiratory tract infections during the period between January and December in 2012 by three societies. Antimicrobial susceptibility testing was conducted at the central reference laboratory according to the method recommended by Clinical Laboratory Standard Institutes. Susceptibility testing was evaluated in 1236 strains (232 Staphylococcus aureus, 225 Streptococcus pneumoniae, 16 Streptococcus pyogenes, 231 Haemophilus influenzae, 147 Moraxella catarrhalis, 167 Klebsiella pneumoniae and 218 Pseudomonas aeruginosa). Ratio of methicillin-resistant S. aureus was 51.3%, and those of penicillin-intermediate S. pneumoniae was 0.4%. Among H. influenzae, 5.6% of them were found to be β-lactamase-producing ampicillin-resistant strains, and 37.2% to be β-lactamase-non-producing ampicillin-resistant strains. Extended spectrum β-lactamase-producing K. pneumoniae and multi-drug resistant P. aeruginosa with metallo β-lactamase were 4.2% and 3.2%, respectively. Continuous national surveillance is important to determine the actual situation of the resistance shown by bacterial respiratory pathogens to antimicrobial agents. Copyright © 2017 Japanese Society of Chemotherapy and The Japanese Association for Infectious Diseases. Published by Elsevier Ltd. All rights reserved.

Relationship with original pathogen in recurrence of acute otitis media after completion of amoxicillin/clavulanate: bacterial relapse or new pathogen.

PubMed

Kaur, Ravinder; Casey, Janet R; Pichichero, Michael E

2013-11-01

We sought to determine whether recurrent acute otitis media (rAOM) occurring within 30 days of amoxicillin/clavulanate treatment was caused by bacterial relapse or new pathogens. Pneumococcal conjugate vaccinated children, age 6-36 months, enrolled in a prospective, longitudinal study experiencing rAOM<1 month after completing amoxicillin/clavulanate therapy were studied. AOM episodes occurred between June 2006 and November 2012. Multilocus sequence typing was used to genotype isolates. Sixty-six children were in the study cohort; 63 otopathogens were recovered from middle ear fluid after tympanocentesis. Nontypeable Haemophilus influenzae (NTHi) accounted for 47% of initial AOMs versus 15% by Streptococcus pneumoniae (Spn), P<0.0001. NTHi accounted for 42% of rAOM versus 24% by Spn (P value=0.04). NTHi was the main otopathogen that caused true bacteriologic relapses (77%). β-lactamase-producing NTHi and penicillin nonsusceptible Spn were not more common in rAOM than initial AOM infections. Among 21 paired (initial and rAOM events) NTHi isolates genotyped, 13 (61.9%) were the same organism; 1 of 9 (11.1%) of paired Spn isolates was the same (P value=0.017). rAOM occurring within a week of stopping amoxicillin/clavulanate was a different pathogen in 21% of cases, 8-14 days later in 33%, 15-21 days in 41% and 22-30 days in 57% (P=0.04). In amoxicillin/clavulanate-treated children, NTHi was the main otopathogen that caused true bacteriologic relapses. New pathogens causing rAOM versus persistence of the initial pathogen significantly increased week to week. Neither relapses nor new infections were caused more frequently by β-lactamase producing NTHi or penicillin nonsusceptible Spn.

Genome of the opportunistic pathogen Streptococcus sanguinis.

PubMed

Xu, Ping; Alves, Joao M; Kitten, Todd; Brown, Arunsri; Chen, Zhenming; Ozaki, Luiz S; Manque, Patricio; Ge, Xiuchun; Serrano, Myrna G; Puiu, Daniela; Hendricks, Stephanie; Wang, Yingping; Chaplin, Michael D; Akan, Doruk; Paik, Sehmi; Peterson, Darrell L; Macrina, Francis L; Buck, Gregory A

2007-04-01

The genome of Streptococcus sanguinis is a circular DNA molecule consisting of 2,388,435 bp and is 177 to 590 kb larger than the other 21 streptococcal genomes that have been sequenced. The G+C content of the S. sanguinis genome is 43.4%, which is considerably higher than the G+C contents of other streptococci. The genome encodes 2,274 predicted proteins, 61 tRNAs, and four rRNA operons. A 70-kb region encoding pathways for vitamin B(12) biosynthesis and degradation of ethanolamine and propanediol was apparently acquired by horizontal gene transfer. The gene complement suggests new hypotheses for the pathogenesis and virulence of S. sanguinis and differs from the gene complements of other pathogenic and nonpathogenic streptococci. In particular, S. sanguinis possesses a remarkable abundance of putative surface proteins, which may permit it to be a primary colonizer of the oral cavity and agent of streptococcal endocarditis and infection in neutropenic patients.

Evaluation of an Internally Controlled Multiplex Tth Endonuclease Cleavage Loop-Mediated Isothermal Amplification (TEC-LAMP) Assay for the Detection of Bacterial Meningitis Pathogens

PubMed Central

Clancy, Eoin; Cormican, Martin; Boo, Teck Wee; Cunney, Robert

2018-01-01

Bacterial meningitis infection is a leading global health concern for which rapid and accurate diagnosis is essential to reduce associated morbidity and mortality. Loop-mediated isothermal amplification (LAMP) offers an effective low-cost diagnostic approach; however, multiplex LAMP is difficult to achieve, limiting its application. We have developed novel real-time multiplex LAMP technology, TEC-LAMP, using Tth endonuclease IV and a unique LAMP primer/probe. This study evaluates the analytical specificity, limit of detection (LOD) and clinical application of an internally controlled multiplex TEC-LAMP assay for detection of leading bacterial meningitis pathogens: Streptococcus pneumoniae, Neisseria meningitidis and Haemophilus influenzae. Analytical specificities were established by testing 168 bacterial strains, and LODs were determined using Probit analysis. The TEC-LAMP assay was 100% specific, with LODs for S. pneumoniae, N. meningitidis and H. influenzae of 39.5, 17.3 and 25.9 genome copies per reaction, respectively. Clinical performance was evaluated by testing 65 archived PCR-positive samples. Compared to singleplex real-time PCR, the multiplex TEC-LAMP assay demonstrated diagnostic sensitivity and specificity of 92.3% and 100%, respectively. This is the first report of a single-tube internally controlled multiplex LAMP assay for bacterial meningitis pathogen detection, and the first report of Tth endonuclease IV incorporation into nucleic acid amplification diagnostic technology. PMID:29425124

The Road to Infection: Host-Microbe Interactions Defining the Pathogenicity of Streptococcus bovis/Streptococcus equinus Complex Members

PubMed Central

Jans, Christoph; Boleij, Annemarie

2018-01-01

The Streptococcus bovis/Streptococcus equinus complex (SBSEC) comprises several species inhabiting the animal and human gastrointestinal tract (GIT). They match the pathobiont description, are potential zoonotic agents and technological organisms in fermented foods. SBSEC members are associated with multiple diseases in humans and animals including ruminal acidosis, infective endocarditis (IE) and colorectal cancer (CRC). Therefore, this review aims to re-evaluate adhesion and colonization abilities of SBSEC members of animal, human and food origin paired with genomic and functional host-microbe interaction data on their road from colonization to infection. SBSEC seem to be a marginal population during GIT symbiosis that can proliferate as opportunistic pathogens. Risk factors for human colonization are considered living in rural areas and animal-feces contact. Niche adaptation plays a pivotal role where Streptococcus gallolyticus subsp. gallolyticus (SGG) retained the ability to proliferate in various environments. Other SBSEC members have undergone genome reduction and niche-specific gene gain to yield important commensal, pathobiont and technological species. Selective colonization of CRC tissue is suggested for SGG, possibly related to increased adhesion to cancerous cell types featuring enhanced collagen IV accessibility. SGG can colonize, proliferate and may shape the tumor microenvironment to their benefit by tumor promotion upon initial neoplasia development. Bacteria cell surface structures including lipotheichoic acids, capsular polysaccharides and pilus loci (pil1, pil2, and pil3) govern adhesion. Only human blood-derived SGG contain complete pilus loci and other disease-associated surface proteins. Rumen or feces-derived SGG and other SBSEC members lack or harbor mutated pili. Pili also contribute to binding to fibrinogen upon invasion and translocation of cells from the GIT into the blood system, subsequent immune evasion, human contact system

Specific detection of common pathogens of acute bacterial meningitis using an internally controlled tetraplex-PCR assay.

PubMed

Farahani, Hamidreza; Ghaznavi-Rad, Ehsanollah; Mondanizadeh, Mahdieh; MirabSamiee, Siamak; Khansarinejad, Behzad

2016-08-01

Accurate and timely diagnosis of acute bacterial meningitis is critical for antimicrobial treatment of patients. Although PCR-based methods have been widely used for the diagnosis of acute meningitis caused by bacterial pathogens, the main disadvantage of these methods is their high cost. This disadvantage has hampered the widespread use of molecular assays in many developing countries. The application of multiplex assays and "in-house" protocols are two main approaches that can reduce the overall cost of a molecular test. In the present study, an internally controlled tetraplex-PCR was developed and validated for the specific detection of Streptococcus pneumoniae, Neisseria meningitidis and Haemophilus influenzae in cerebrospinal fluid (CSF) samples. The analysis of a panel of other human pathogens showed no cross-reactivity in the assay. The analytical sensitivity of the in-house assay was 792.3 copies/ml, when all three bacteria were presentin the specimens. This value was calculated as 444.5, 283.7, 127.8 copies/ml when only S. pneumoniae, N. meningitidis and H. influenzae, respectively, were present. To demonstrate the diagnostic performance of the assay, a total of 150 archival CSF samples were tested and compared with a commercial multiplex real-time PCR kit. A diagnostic sensitivity of 92.8% and a specificity of 95.1% were determined for the present tetraplex-PCR assay. The results indicate that the established method is sensitive, specific and cost-effective, and can be used particularly in situations where the high cost of commercial kits prevents the use of molecular methods for the diagnosis of bacterial meningitis. Copyright © 2016 Elsevier Ltd. All rights reserved.

Additive genetic variation in resistance of Nile tilapia (Oreochromis niloticus) to Streptococcus iniae and S. agalactiae capsular type Ib: is genetic resistance correlated?

USDA-ARS?s Scientific Manuscript database

Streptococcus (S.) iniae and S. agalactiae are both economically important Gram positive bacterial pathogens affecting the globally farmed tilapia (Oreochromis spp.). Historically control of these bacteria in tilapia culture has included biosecurity, therapeutants and vaccination strategies. Genet...

Increased detection of mastitis pathogens by real-time PCR compared to bacterial culture.

PubMed

Keane, O M; Budd, K E; Flynn, J; McCoy, F

2013-09-21

Rapid and accurate identification of mastitis pathogens is important for disease control. Bacterial culture and isolate identification is considered the gold standard in mastitis diagnosis but is time consuming and results in many culture-negative samples. Identification of mastitis pathogens by PCR has been proposed as a fast and sensitive alternative to bacterial culture. The results of bacterial culture and PCR for the identification of the aetiological agent of clinical mastitis were compared. The pathogen identified by traditional culture methods was also detected by PCR in 98 per cent of cases indicating good agreement between the positive results of bacterial culture and PCR. A mastitis pathogen could not be recovered from approximately 30 per cent of samples by bacterial culture, however, an aetiological agent was identified by PCR in 79 per cent of these samples. Therefore, a mastitis pathogen was detected in significantly more milk samples by PCR than by bacterial culture (92 per cent and 70 per cent, respectively) although the clinical relevance of PCR-positive culture-negative results remains controversial. A mixed infection of two or more mastitis pathogens was also detected more commonly by PCR. Culture-negative samples due to undetected Staphylococcus aureus infections were rare. The use of PCR technology may assist in rapid mastitis diagnosis, however, accurate interpretation of PCR results in the absence of bacterial culture remains problematic.

Menaquinone analogs inhibit growth of bacterial pathogens.

PubMed

Schlievert, Patrick M; Merriman, Joseph A; Salgado-Pabón, Wilmara; Mueller, Elizabeth A; Spaulding, Adam R; Vu, Bao G; Chuang-Smith, Olivia N; Kohler, Petra L; Kirby, John R

2013-11-01

Gram-positive bacteria cause serious human illnesses through combinations of cell surface and secreted virulence factors. We initiated studies with four of these organisms to develop novel topical antibacterial agents that interfere with growth and exotoxin production, focusing on menaquinone analogs. Menadione, 1,4-naphthoquinone, and coenzymes Q1 to Q3 but not menaquinone, phylloquinone, or coenzyme Q10 inhibited the growth and to a greater extent exotoxin production of Staphylococcus aureus, Bacillus anthracis, Streptococcus pyogenes, and Streptococcus agalactiae at concentrations of 10 to 200 μg/ml. Coenzyme Q1 reduced the ability of S. aureus to cause toxic shock syndrome in a rabbit model, inhibited the growth of four Gram-negative bacteria, and synergized with another antimicrobial agent, glycerol monolaurate, to inhibit S. aureus growth. The staphylococcal two-component system SrrA/B was shown to be an antibacterial target of coenzyme Q1. We hypothesize that menaquinone analogs both induce toxic reactive oxygen species and affect bacterial plasma membranes and biosynthetic machinery to interfere with two-component systems, respiration, and macromolecular synthesis. These compounds represent a novel class of potential topical therapeutic agents.

The novel polysaccharide deacetylase homologue Pdi contributes to virulence of the aquatic pathogen Streptococcus iniae

PubMed Central

Milani, Carlo J. E.; Aziz, Ramy K.; Locke, Jeffrey B.; Dahesh, Samira; Nizet, Victor; Buchanan, John T.

2010-01-01

The aquatic zoonotic pathogen Streptococcus iniae represents a threat to the worldwide aquaculture industry and poses a risk to humans who handle raw fish. Because little is known about the mechanisms of S. iniae pathogenesis or virulence factors, we established a high-throughput system combining whole-genome pyrosequencing and transposon mutagenesis that allowed us to identify virulence proteins, including Pdi, the polysaccharide deacetylase of S. iniae, that we describe here. Using bioinformatics tools, we identified a highly conserved signature motif in Pdi that is also conserved in the peptidoglycan deacetylase PgdA protein family. A Δpdi mutant was attenuated for virulence in the hybrid striped bass model and for survival in whole fish blood. Moreover, Pdi was found to promote bacterial resistance to lysozyme killing and the ability to adhere to and invade epithelial cells. On the other hand, there was no difference in the autolytic potential, resistance to oxidative killing or resistance to cationic antimicrobial peptides between S. iniae wild-type and Δpdi. In conclusion, we have demonstrated that pdi is involved in S. iniae adherence and invasion, lysozyme resistance and survival in fish blood, and have shown that pdi plays a role in the pathogenesis of S. iniae. Identification of Pdi and other S. iniae virulence proteins is a necessary initial step towards the development of appropriate preventive and therapeutic measures against diseases and economic losses caused by this pathogen. PMID:19762441

Axially substituted silicon(IV) phthalocyanine and its quaternized derivative as photosensitizers towards tumor cells and bacterial pathogens.

PubMed

Ömeroğlu, İpek; Kaya, Esra Nur; Göksel, Meltem; Kussovski, Vesselin; Mantareva, Vanya; Durmuş, Mahmut

2017-10-15

Axially di-(alpha,alpha-diphenyl-4-pyridylmethoxy) silicon(IV) phthalocyanine (3) and its quaternized derivative (3Q) were synthesized and tested as photosensitizers against tumor and bacterial cells. These new phthalocyanines were characterized by elemental analysis, and different spectroscopic methods such as FT-IR, UV-Vis, MALDI-TOF and 1 H NMR. The photophysical properties such as absorption and fluorescence, and the photochemical properties such as singlet oxygen generation of both phthalocyanines were investigated in solutions. The obtained values were compared to the values obtained with unsubstituted silicon(IV) phthalocyanine dichloride (SiPcCl 2 ). The addition of two di-(alpha,alpha-diphenyl-4-pyridylmethanol) groups as axial ligands showed an improvement of the photophysical and photochemical properties and an increasement of the singlet oxygen quantum yield (Φ Δ ) from 0.15 to 0.33 was determined. The photodynamic efficacy of synthesized photosensitizers (3 and 3Q) were evaluated with promising photocytotoxicity (17% cell survival for 3 and 28% for 3Q) against the cervical cancer cell line (HeLa). The photodynamic inactivation of pathogenic bacterial strains Streptococcus mutans, Staphylococcus aureus, and Pseudomonas aeruginosa suggested a high susceptibility with quaternized derivative (3Q). The both Gram-positive bacterial strains were fully photoinactivated with 11μM 3Q and mild light dose 50J.cm -2 . In case of P. aeruginosa the effect was negligible for concentrations up to 22μM 3Q and light dose 100J.cm -2 . The results suggested that the novel axially substituted silicon(IV) phthalocyanines have promising characteristic as photosensitizer towards tumor cells. The quaternized derivative 3Q has high potential for photoinactivation of pathogenic bacterial species. Copyright © 2017 Elsevier Ltd. All rights reserved.

Poisons, ruffles and rockets: bacterial pathogens and the host cell cytoskeleton.

PubMed

Steele-Mortimer, O; Knodler, L A; Finlay, B B

2000-02-01

The cytoskeleton of eukaryotic cells is affected by a number of bacterial and viral pathogens. In this review we consider three recurring themes of cytoskeletal involvement in bacterial pathogenesis: 1) the effect of bacterial toxins on actin-regulating small GTP-binding proteins; 2) the invasion of non-phagocytic cells by the bacterial induction of ruffles at the plasma membrane; 3) the formation of actin tails and pedestals by intracellular and extracellular bacteria, respectively. Considerable progress has been made recently in the characterization of these processes. It is becoming clear that bacterial pathogens have developed a variety of sophisticated mechanisms for utilizing the complex cytoskeletal system of host cells. These bacterially-induced processes are now providing unique insights into the regulation of fundamental eukaryotic mechanisms.

Development of Primer Sets for Loop-Mediated Isothermal Amplification that Enables Rapid and Specific Detection of Streptococcus dysgalactiae, Streptococcus uberis and Streptococcus agalactiae.

PubMed

Wang, Deguo; Liu, Yanhong

2015-05-26

Streptococcus dysgalactiae, Streptococcus uberis and Streptococcus agalactiae are the three main pathogens causing bovine mastitis, with great losses to the dairy industry. Rapid and specific loop-mediated isothermal amplification methods (LAMP) for identification and differentiation of these three pathogens are not available. With the 16S rRNA gene and 16S-23S rRNA intergenic spacers as targets, four sets of LAMP primers were designed for identification and differentiation of S. dysgalactiae, S. uberis and S. agalactiae. The detection limit of all four LAMP primer sets were 0.1 pg DNA template per reaction, the LAMP method with 16S rRNA gene and 16S-23S rRNA intergenic spacers as the targets can differentiate the three pathogens, which is potentially useful in epidemiological studies.

First Isolation of Streptococcus halichoeri and Streptococcus phocae from a Steller Sea Lion (Eumetopias jubatus) in South Korea.

PubMed

Lee, Kichan; Kim, Ji-Yeon; Jung, Suk Chan; Lee, Hee-Soo; Her, Moon; Chae, Chanhee

2016-01-01

Streptococcus species are emerging potential pathogens in marine mammals. We report the isolation and identification of Streptococcus halichoeri and Streptococcus phocae in a Steller sea lion (Eumetopias jubatus) in South Korea.

Genetic reprogramming of host cells by bacterial pathogens.

PubMed

Tran Van Nhieu, Guy; Arbibe, Laurence

2009-10-29

During the course of infection, pathogens often induce changes in gene expression in host cells and these changes can be long lasting and global or transient and of limited amplitude. Defining how, when, and why bacterial pathogens reprogram host cells represents an exciting challenge that opens up the opportunity to grasp the essence of pathogenesis and its molecular details.

Manipulation of host membranes by the bacterial pathogens Listeria, Francisella, Shigella and Yersinia.

PubMed

Pizarro-Cerdá, Javier; Charbit, Alain; Enninga, Jost; Lafont, Frank; Cossart, Pascale

2016-12-01

Bacterial pathogens display an impressive arsenal of molecular mechanisms that allow survival in diverse host niches. Subversion of plasma membrane and cytoskeletal functions are common themes associated to infection by both extracellular and intracellular pathogens. Moreover, intracellular pathogens modify the structure/stability of their membrane-bound compartments and escape degradation from phagocytic or autophagic pathways. Here, we review the manipulation of host membranes by Listeria monocytogenes, Francisella tularensis, Shigella flexneri and Yersinia spp. These four bacterial model pathogens exemplify generalized strategies as well as specific features observed during bacterial infection processes. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

Incidence of bacterial respiratory pathogens and their susceptibility to common antibacterial agents.

PubMed Central

Qadri, S. M.; Lee, G. C.; Ueno, Y.; Burdette, J. M.

1993-01-01

Although most respiratory tract infections are caused by viruses, bacterial pathogens are responsible for higher morbidity and mortality. Because virtually nothing is known about the etiology of bacterial respiratory pathogens in Saudi Arabia, this study examined the incidence of these organisms in 5426 patients over a 1-year period. Of the bacterial pathogens isolated from 904 patients, the most common organism was Hemophilus influenzae (31%), followed by pneumococci (22%), Pseudomonas aeruginosa (16%), and others (31%). Because the first two organisms accounted for more than 50% of isolates, their susceptibility to commonly used antibiotics was also reviewed. The results are presented here. PMID:8496993

Bacterial pathogen manipulation of host membrane trafficking.

PubMed

Asrat, Seblewongel; de Jesús, Dennise A; Hempstead, Andrew D; Ramabhadran, Vinay; Isberg, Ralph R

2014-01-01

Pathogens use a vast number of strategies to alter host membrane dynamics. Targeting the host membrane machinery is important for the survival and pathogenesis of several extracellular, vacuolar, and cytosolic bacteria. Membrane manipulation promotes bacterial replication while suppressing host responses, allowing the bacterium to thrive in a hostile environment. This review provides a comprehensive summary of various strategies used by both extracellular and intracellular bacteria to hijack host membrane trafficking machinery. We start with mechanisms used by bacteria to alter the plasma membrane, delve into the hijacking of various vesicle trafficking pathways, and conclude by summarizing bacterial adaptation to host immune responses. Understanding bacterial manipulation of host membrane trafficking provides insights into bacterial pathogenesis and uncovers the molecular mechanisms behind various processes within a eukaryotic cell.

Streptococcus suis serotype 9 strain GZ0565 contains a type VII secretion system putative substrate EsxA that contributes to bacterial virulence and a vanZ-like gene that confers resistance to teicoplanin and dalbavancin in Streptococcus agalactiae.

PubMed

Lai, Liying; Dai, Jiao; Tang, Huanyu; Zhang, Shouming; Wu, Chunyan; Qiu, Wancen; Lu, Chengping; Yao, Huochun; Fan, Hongjie; Wu, Zongfu

2017-06-01

Streptococcus suis (SS), an important pathogen for pigs, is not only considered as a zoonotic agent for humans, but is also recognized as a major reservoir of antimicrobial resistance contributing to the spread of resistance genes to other pathogenic Streptococcus species. In addition to serotype 2 (SS2), serotype 9 (SS9) is another prevalent serotype isolated from diseased pigs. Although many SS strains have been sequenced, the complete genome of a non-SS2 virulent strain has been unavailable to date. Here, we report the complete genome of GZ0565, a virulent strain of SS9, isolated from a pig with meningitis. Comparative genomic analysis revealed five new putative virulence or antimicrobial resistance-associated genes in strain GZ0565 but not in SS2 virulent strains. These five genes encode a putative triacylglycerol lipase, a TipAS antibiotic-recognition domain protein, a putative TetR family transcriptional repressor, a protein containing a LPXTG domain and a G5 domain, and a type VII secretion system (T7SS) putative substrate (EsxA), respectively. Western blot analysis showed that strain GZ0565 can secrete EsxA. We generated an esxA deletion mutant and showed that EsxA contributes to SS virulence in a mouse infection model. Additionally, the antibiotic resistance gene vanZ SS was identified and expression of vanZ SS conferred resistance to teicoplanin and dalbavancin in Streptococcus agalactiae. We believe this is the first experimental demonstration of the existence of the T7SS putative substrate EsxA and its contribution to bacterial virulence in SS. Together, our results contribute to further understanding of the virulence and antimicrobial resistance characteristics of SS. Copyright © 2017 Elsevier B.V. All rights reserved.

[Microbiology of bronchoalveolar lavage in infants with bacterial community-acquired pneumonia with poor outcome].

PubMed

García-Elorriaga, Guadalupe; Palma-Alaniz, Laura; García-Bolaños, Carlos; Ruelas-Vargas, Consuelo; Méndez-Tovar, Socorro; Del Rey-Pineda, Guillermo

Community-acquired pneumonia (CAP) is one of the most common infectious causes of morbidity and mortality in children <5 years of age. The aim of the study was to clarify the bacterial etiologic diagnosis in infants with CAP. A prospective, cross-sectional and descriptive study in patients 6 months to 2 years 11 months of age with CAP with poor outcome was conducted. Patients were admitted to the Pediatric Pneumology Service and underwent bronchoscopy with bronchoalveolar lavage (BAL), taking appropriate measures during the procedure to limit the risk of contamination. Aerobic bacteria isolated were Moraxella sp. 23%, Streptococcus mitis 23%, Streptococcus pneumoniae 18%, Haemophilus influenzae 12%, Streptococcus oralis 12%, and Streptococcus salivarius 12%. In contrast to other reports, we found Moraxella sp. to be a major bacterial pathogen, possibly because of improved detection with bronchoscopy plus BAL. Copyright © 2015 Hospital Infantil de México Federico Gómez. Publicado por Masson Doyma México S.A. All rights reserved.

Novel bacteriophage lysin with broad lytic activity protects against mixed infection by Streptococcus pyogenes and methicillin-resistant Staphylococcus aureus.

PubMed

Gilmer, Daniel B; Schmitz, Jonathan E; Euler, Chad W; Fischetti, Vincent A

2013-06-01

Methicillin-resistant Staphylococcus aureus (MRSA) and Streptococcus pyogenes (group A streptococcus [GrAS]) cause serious and sometimes fatal human diseases. They are among the many Gram-positive pathogens for which resistance to leading antibiotics has emerged. As a result, alternative therapies need to be developed to combat these pathogens. We have identified a novel bacteriophage lysin (PlySs2), derived from a Streptococcus suis phage, with broad lytic activity against MRSA, vancomycin-intermediate S. aureus (VISA), Streptococcus suis, Listeria, Staphylococcus simulans, Staphylococcus epidermidis, Streptococcus equi, Streptococcus agalactiae (group B streptococcus [GBS]), S. pyogenes, Streptococcus sanguinis, group G streptococci (GGS), group E streptococci (GES), and Streptococcus pneumoniae. PlySs2 has an N-terminal cysteine-histidine aminopeptidase (CHAP) catalytic domain and a C-terminal SH3b binding domain. It is stable at 50 °C for 30 min, 37 °C for >24 h, 4°C for 15 days, and -80 °C for >7 months; it maintained full activity after 10 freeze-thaw cycles. PlySs2 at 128 μg/ml in vitro reduced MRSA and S. pyogenes growth by 5 logs and 3 logs within 1 h, respectively, and exhibited a MIC of 16 μg/ml for MRSA. A single, 2-mg dose of PlySs2 protected 92% (22/24) of the mice in a bacteremia model of mixed MRSA and S. pyogenes infection. Serially increasing exposure of MRSA and S. pyogenes to PlySs2 or mupirocin resulted in no observed resistance to PlySs2 and resistance to mupirocin. To date, no other lysin has shown such notable broad lytic activity, stability, and efficacy against multiple, leading, human bacterial pathogens; as such, PlySs2 has all the characteristics to be an effective therapeutic.

Mechanisms of group A Streptococcus resistance to reactive oxygen species

PubMed Central

Henningham, Anna; Döhrmann, Simon; Nizet, Victor; Cole, Jason N.

2015-01-01

Streptococcus pyogenes, also known as group A Streptococcus (GAS), is an exclusively human Gram-positive bacterial pathogen ranked among the ‘top 10’ causes of infection-related deaths worldwide. GAS commonly causes benign and self-limiting epithelial infections (pharyngitis and impetigo), and less frequent severe invasive diseases (bacteremia, toxic shock syndrome and necrotizing fasciitis). Annually, GAS causes 700 million infections, including 1.8 million invasive infections with a mortality rate of 25%. In order to establish an infection, GAS must counteract the oxidative stress conditions generated by the release of reactive oxygen species (ROS) at the infection site by host immune cells such as neutrophils and monocytes. ROS are the highly reactive and toxic byproducts of oxygen metabolism, including hydrogen peroxide (H2O2), superoxide anion (O2•−), hydroxyl radicals (OH•) and singlet oxygen (O2*), which can damage bacterial nucleic acids, proteins and cell membranes. This review summarizes the enzymatic and regulatory mechanisms utilized by GAS to thwart ROS and survive under conditions of oxidative stress. PMID:25670736

Mechanisms of group A Streptococcus resistance to reactive oxygen species.

PubMed

Henningham, Anna; Döhrmann, Simon; Nizet, Victor; Cole, Jason N

2015-07-01

Streptococcus pyogenes, also known as group A Streptococcus (GAS), is an exclusively human Gram-positive bacterial pathogen ranked among the 'top 10' causes of infection-related deaths worldwide. GAS commonly causes benign and self-limiting epithelial infections (pharyngitis and impetigo), and less frequent severe invasive diseases (bacteremia, toxic shock syndrome and necrotizing fasciitis). Annually, GAS causes 700 million infections, including 1.8 million invasive infections with a mortality rate of 25%. In order to establish an infection, GAS must counteract the oxidative stress conditions generated by the release of reactive oxygen species (ROS) at the infection site by host immune cells such as neutrophils and monocytes. ROS are the highly reactive and toxic byproducts of oxygen metabolism, including hydrogen peroxide (H2O2), superoxide anion (O2•(-)), hydroxyl radicals (OH•) and singlet oxygen (O2*), which can damage bacterial nucleic acids, proteins and cell membranes. This review summarizes the enzymatic and regulatory mechanisms utilized by GAS to thwart ROS and survive under conditions of oxidative stress. © FEMS 2015.

Investigation of magnetic microdiscs for bacterial pathogen detection

NASA Astrophysics Data System (ADS)

Castillo-Torres, Keisha Y.; Garraud, Nicolas; Arnold, David P.; McLamore, Eric S.

2016-05-01

Despite strict regulations to control the presence of human pathogens in our food supply, recent foodborne outbreaks have heightened public concern about food safety and created urgency to improve methods for pathogen detection. Herein we explore a potentially portable, low-cost system that uses magnetic microdiscs for the detection of bacterial pathogens in liquid samples. The system operates by optically measuring the rotational dynamics of suspended magnetic microdiscs functionalized with pathogen-binding aptamers. The soft ferromagnetic (Ni80Fe20) microdiscs exhibit a closed magnetic spin arrangement (i.e. spin vortex) with zero magnetic stray field, leading to no disc agglomeration when in free suspension. With very high surface area for functionalization and volumes 10,000x larger than commonly used superparamagnetic nanoparticles, these 1.5-μm-diameter microdiscs are well suited for tagging, trapping, actuating, or interrogating bacterial targets. This work reports a wafer-level microfabrication process for fabrication of 600 million magnetic microdiscs per substrate and measurement of their rotational dynamics response. Additionally, the biofunctionalization of the microdiscs with DNA aptamers, subsequent binding to E. coli bacteria, and their magnetic manipulation is reported.

Prevalence of gastrointestinal bacterial pathogens in a population of zoo animals.

PubMed

Stirling, J; Griffith, M; Blair, I; Cormican, M; Dooley, J S G; Goldsmith, C E; Glover, S G; Loughrey, A; Lowery, C J; Matsuda, M; McClurg, R; McCorry, K; McDowell, D; McMahon, A; Cherie Millar, B; Nagano, Y; Rao, J R; Rooney, P J; Smyth, M; Snelling, W J; Xu, J; Moore, J E

2008-04-01

Faecal prevalence of gastrointestinal bacterial pathogens, including Campylobacter, Escherichia coli O157:H7, Salmonella, Shigella, Yersinia, as well as Arcobacter, were examined in 317 faecal specimens from 44 animal species in Belfast Zoological Gardens, during July-September 2006. Thermophilic campylobacters including Campylobacter jejuni, Campylobacter coli and Campylobacter lari, were the most frequently isolated pathogens, where members of this genus were isolated from 11 animal species (11 of 44; 25%). Yersinia spp. were isolated from seven animal species (seven of 44; 15.9%) and included, Yersinia enterocolitica (five of seven isolates; 71.4%) and one isolate each of Yersinia frederiksenii and Yersinia kristensenii. Only one isolate of Salmonella was obtained throughout the entire study, which was an isolate of Salmonella dublin (O 1,9,12: H g, p), originating from tiger faeces after enrichment. None of the animal species found in public contact areas of the zoo were positive for any gastrointestinal bacterial pathogens. Also, water from the lake in the centre of the grounds, was examined for the same bacterial pathogens and was found to contain C. jejuni. This study is the first report on the isolation of a number of important bacterial pathogens from a variety of novel host species, C. jejuni from the red kangaroo (Macropus rufus), C. lari from a maned wolf (Chrysocyon brachyurus), Y. kristensenii from a vicugna (Vicugna vicugna) and Y. enterocolitica from a maned wolf and red panda (Ailurus fulgens). In conclusion, this study demonstrated that the faeces of animals in public contact areas of the zoo were not positive for the bacterial gastrointestinal pathogens examined. This is reassuring for the public health of visitors, particularly children, who enjoy this educational and recreational resource.

Recognition of bacterial plant pathogens: local, systemic and transgenerational immunity.

PubMed

Henry, Elizabeth; Yadeta, Koste A; Coaker, Gitta

2013-09-01

Bacterial pathogens can cause multiple plant diseases and plants rely on their innate immune system to recognize and actively respond to these microbes. The plant innate immune system comprises extracellular pattern recognition receptors that recognize conserved microbial patterns and intracellular nucleotide binding leucine-rich repeat (NLR) proteins that recognize specific bacterial effectors delivered into host cells. Plants lack the adaptive immune branch present in animals, but still afford flexibility to pathogen attack through systemic and transgenerational resistance. Here, we focus on current research in plant immune responses against bacterial pathogens. Recent studies shed light onto the activation and inactivation of pattern recognition receptors and systemic acquired resistance. New research has also uncovered additional layers of complexity surrounding NLR immune receptor activation, cooperation and sub-cellular localizations. Taken together, these recent advances bring us closer to understanding the web of molecular interactions responsible for coordinating defense responses and ultimately resistance. © 2013 The Authors. New Phytologist © 2013 New Phytologist Trust.

Live Attenuated Influenza Vaccine Enhances Colonization of Streptococcus pneumoniae and Staphylococcus aureus in Mice

PubMed Central

Mina, Michael J.; McCullers, Jonathan A.; Klugman, Keith P.

2014-01-01

ABSTRACT Community interactions at mucosal surfaces between viruses, like influenza virus, and respiratory bacterial pathogens are important contributors toward pathogenesis of bacterial disease. What has not been considered is the natural extension of these interactions to live attenuated immunizations, and in particular, live attenuated influenza vaccines (LAIVs). Using a mouse-adapted LAIV against influenza A (H3N2) virus carrying the same mutations as the human FluMist vaccine, we find that LAIV vaccination reverses normal bacterial clearance from the nasopharynx and significantly increases bacterial carriage densities of the clinically important bacterial pathogens Streptococcus pneumoniae (serotypes 19F and 7F) and Staphylococcus aureus (strains Newman and Wright) within the upper respiratory tract of mice. Vaccination with LAIV also resulted in 2- to 5-fold increases in mean durations of bacterial carriage. Furthermore, we show that the increases in carriage density and duration were nearly identical in all aspects to changes in bacterial colonizing dynamics following infection with wild-type (WT) influenza virus. Importantly, LAIV, unlike WT influenza viruses, had no effect on severe bacterial disease or mortality within the lower respiratory tract. Our findings are, to the best of our knowledge, the first to demonstrate that vaccination with a live attenuated viral vaccine can directly modulate colonizing dynamics of important and unrelated human bacterial pathogens, and does so in a manner highly analogous to that seen following wild-type virus infection. PMID:24549845

Adenoid Reservoir for Pathogenic Biofilm Bacteria▿

PubMed Central

Nistico, L.; Kreft, R.; Gieseke, A.; Coticchia, J. M.; Burrows, A.; Khampang, P.; Liu, Y.; Kerschner, J. E.; Post, J. C.; Lonergan, S.; Sampath, R.; Hu, F. Z.; Ehrlich, G. D.; Stoodley, P.; Hall-Stoodley, L.

2011-01-01

Biofilms of pathogenic bacteria are present on the middle ear mucosa of children with chronic otitis media (COM) and may contribute to the persistence of pathogens and the recalcitrance of COM to antibiotic treatment. Controlled studies indicate that adenoidectomy is effective in the treatment of COM, suggesting that the adenoids may act as a reservoir for COM pathogens. To investigate the bacterial community in the adenoid, samples were obtained from 35 children undergoing adenoidectomy for chronic OM or obstructive sleep apnea. We used a novel, culture-independent molecular diagnostic methodology, followed by confocal microscopy, to investigate the in situ distribution and organization of pathogens in the adenoids to determine whether pathogenic bacteria exhibited criteria characteristic of biofilms. The Ibis T5000 Universal Biosensor System was used to interrogate the extent of the microbial diversity within adenoid biopsy specimens. Using a suite of 16 broad-range bacterial primers, we demonstrated that adenoids from both diagnostic groups were colonized with polymicrobial biofilms. Haemophilus influenzae was present in more adenoids from the COM group (P = 0.005), but there was no significant difference between the two patient groups for Streptococcus pneumoniae or Staphylococcus aureus. Fluorescence in situ hybridization, lectin binding, and the use of antibodies specific for host epithelial cells demonstrated that pathogens were aggregated, surrounded by a carbohydrate matrix, and localized on and within the epithelial cell surface, which is consistent with criteria for bacterial biofilms. PMID:21307211

Water relations in the interaction of foliar bacterial pathogens with plants.

PubMed

Beattie, Gwyn A

2011-01-01

This review examines the many ways in which water influences the relations between foliar bacterial pathogens and plants. As a limited resource in aerial plant tissues, water is subject to manipulation by both plants and pathogens. A model is emerging that suggests that plants actively promote localized desiccation at the infection site and thus restrict pathogen growth as one component of defense. Similarly, many foliar pathogens manipulate water relations as one component of pathogenesis. Nonvascular pathogens do this using effectors and other molecules to alter hormonal responses and enhance intercellular watersoaking, whereas vascular pathogens use many mechanisms to cause wilt. Because of water limitations on phyllosphere surfaces, bacterial colonists, including pathogens, benefit from the protective effects of cellular aggregation, synthesis of hygroscopic polymers, and uptake and production of osmoprotective compounds. Moreover, these bacteria employ tactics for scavenging and distributing water to overcome water-driven barriers to nutrient acquisition, movement, and signal exchange on plant surfaces. Copyright © 2011 by Annual Reviews. All rights reserved.

The intrinsic resistome of bacterial pathogens

PubMed Central

Olivares, Jorge; Bernardini, Alejandra; Garcia-Leon, Guillermo; Corona, Fernando; B. Sanchez, Maria; Martinez, Jose L.

2013-01-01

Intrinsically resistant bacteria have emerged as a relevant health problem in the last years. Those bacterial species, several of them with an environmental origin, present naturally low-level susceptibility to several drugs. It has been proposed that intrinsic resistance is mainly the consequence of the impermeability of cellular envelopes, the activity of multidrug efflux pumps or the lack of appropriate targets for a given family of drugs. However, recently published articles indicate that the characteristic phenotype of susceptibility to antibiotics of a given bacterial species depends on the concerted activity of several elements, what has been named as intrinsic resistome. These determinants comprise not just classical resistance genes. Other elements, several of them involved in basic bacterial metabolic processes, are of relevance for the intrinsic resistance of bacterial pathogens. In the present review we analyze recent publications on the intrinsic resistomes of Escherichia coli and Pseudomonas aeruginosa. We present as well information on the role that global regulators of bacterial metabolism, as Crc from P. aeruginosa, may have on modulating bacterial susceptibility to antibiotics. Finally, we discuss the possibility of searching inhibitors of the intrinsic resistome in the aim of improving the activity of drugs currently in use for clinical practice. PMID:23641241

The intrinsic resistome of bacterial pathogens.

PubMed

Olivares, Jorge; Bernardini, Alejandra; Garcia-Leon, Guillermo; Corona, Fernando; B Sanchez, Maria; Martinez, Jose L

2013-01-01

Intrinsically resistant bacteria have emerged as a relevant health problem in the last years. Those bacterial species, several of them with an environmental origin, present naturally low-level susceptibility to several drugs. It has been proposed that intrinsic resistance is mainly the consequence of the impermeability of cellular envelopes, the activity of multidrug efflux pumps or the lack of appropriate targets for a given family of drugs. However, recently published articles indicate that the characteristic phenotype of susceptibility to antibiotics of a given bacterial species depends on the concerted activity of several elements, what has been named as intrinsic resistome. These determinants comprise not just classical resistance genes. Other elements, several of them involved in basic bacterial metabolic processes, are of relevance for the intrinsic resistance of bacterial pathogens. In the present review we analyze recent publications on the intrinsic resistomes of Escherichia coli and Pseudomonas aeruginosa. We present as well information on the role that global regulators of bacterial metabolism, as Crc from P. aeruginosa, may have on modulating bacterial susceptibility to antibiotics. Finally, we discuss the possibility of searching inhibitors of the intrinsic resistome in the aim of improving the activity of drugs currently in use for clinical practice.

Gene Repertoire Evolution of Streptococcus pyogenes Inferred from Phylogenomic Analysis with Streptococcus canis and Streptococcus dysgalactiae

PubMed Central

Lefébure, Tristan; Richards, Vince P.; Lang, Ping; Pavinski-Bitar, Paulina; Stanhope, Michael J.

2012-01-01

Streptococcus pyogenes, is an important human pathogen classified within the pyogenic group of streptococci, exclusively adapted to the human host. Our goal was to employ a comparative evolutionary approach to better understand the genomic events concomitant with S. pyogenes human adaptation. As part of ascertaining these events, we sequenced the genome of one of the potential sister species, the agricultural pathogen S. canis, and combined it in a comparative genomics reconciliation analysis with two other closely related species, Streptococcus dysgalactiae and Streptococcus equi, to determine the genes that were gained and lost during S. pyogenes evolution. Genome wide phylogenetic analyses involving 15 Streptococcus species provided convincing support for a clade of S. equi, S. pyogenes, S. dysgalactiae, and S. canis and suggested that the most likely S. pyogenes sister species was S. dysgalactiae. The reconciliation analysis identified 113 genes that were gained on the lineage leading to S. pyogenes. Almost half (46%) of these gained genes were phage associated and 14 showed significant matches to experimentally verified bacteria virulence factors. Subsequent to the origin of S. pyogenes, over half of the phage associated genes were involved in 90 different LGT events, mostly involving different strains of S. pyogenes, but with a high proportion involving the horse specific pathogen S. equi subsp. equi, with the directionality almost exclusively (86%) in the S. pyogenes to S. equi direction. Streptococcus agalactiae appears to have played an important role in the evolution of S. pyogenes with a high proportion of LGTs originating from this species. Overall the analysis suggests that S. pyogenes adaptation to the human host was achieved in part by (i) the integration of new virulence factors (e.g. speB, and the sal locus) and (ii) the construction of new regulation networks (e.g. rgg, and to some extent speB). PMID:22666370

Childhood Acute Bacterial Meningitis: Clinical Spectrum, Bacteriological Profile and Outcome.

PubMed

Bari, Attia; Zeeshan, Fatima; Zafar, Aiza; Ejaz, Hassan; Iftikhar, Aisha; Rathore, Ahsan Waheed

2016-10-01

To determine the disease pattern, etiological agents and outcome of childhood acute bacterial meningitis. Adescriptive study. Department of Paediatric Medicine, The Children's Hospital, Lahore, from January to December 2012. Atotal of 199 children between the ages of 1 month and 5 years, admitted with the diagnosis of meningitis on the basis of clinical findings and positive cerebrospinal fluid (CSF), were included. In all patients, complete blood count (CBC), CSF culture sensitivity, and blood culture sensitivity were performed. Data was analysed using SPSS version 20. Out of 199 children, 127 (63.8%) were males with M:F ratio of 1.7:1. Mean age was 11.33 ±12 months. Maximum numbers of children were < 1 year of age, 136 (68.3%). Only 90 (45.2%) children were fully vaccinated according to Expanded Program of Immunisation (EPI) schedule. Presentations with refusal to take feed (p=0.008) and with impaired conscious state were independent predictors of death (p=0.002). Complications were noted in 34 (17%) and were significantly associated with severe malnutrition (p=0.006) and altered conscious level at presentation (p < 0.001). The common pathogens identified on CSF culture were coagulase negative staphylococci (CoNS) in 11 (5.5%) and streptococcus pneumoniaein 5 (2.5%). Overall mortality was 10.1%. The commonest pathogen isolated from children who died was streptococcus pneumoniae(p=0.039). Acute bacterial meningitis mostly affected children under the age of 1 year. CSF culture revealed both Grampositive and Gram-negative bacteria. The most common pathogen in children who died was streptococcus pneumoniae.

Novel Regulatory Small RNAs in Streptococcus pyogenes

PubMed Central

Tesorero, Rafael A.; Yu, Ning; Wright, Jordan O.; Svencionis, Juan P.; Cheng, Qiang; Kim, Jeong-Ho; Cho, Kyu Hong

2013-01-01

Streptococcus pyogenes (Group A Streptococcus or GAS) is a Gram-positive bacterial pathogen that has shown complex modes of regulation of its virulence factors to cause diverse diseases. Bacterial small RNAs are regarded as novel widespread regulators of gene expression in response to environmental signals. Recent studies have revealed that several small RNAs (sRNAs) have an important role in S. pyogenes physiology and pathogenesis by regulating gene expression at the translational level. To search for new sRNAs in S. pyogenes, we performed a genomewide analysis through computational prediction followed by experimental verification. To overcome the limitation of low accuracy in computational prediction, we employed a combination of three different computational algorithms (sRNAPredict, eQRNA and RNAz). A total of 45 candidates were chosen based on the computational analysis, and their transcription was analyzed by reverse-transcriptase PCR and Northern blot. Through this process, we discovered 7 putative novel trans-acting sRNAs. Their abundance varied between different growth phases, suggesting that their expression is influenced by environmental or internal signals. Further, to screen target mRNAs of an sRNA, we employed differential RNA sequencing analysis. This study provides a significant resource for future study of small RNAs and their roles in physiology and pathogenesis of S. pyogenes. PMID:23762235

Microbiome analysis reveals the abundance of bacterial pathogens in Rousettus leschenaultii guano

PubMed Central

Banskar, Sunil; Bhute, Shrikant S.; Suryavanshi, Mangesh V.; Punekar, Sachin; Shouche, Yogesh S.

2016-01-01

Bats are crucial for proper functioning of an ecosystem. They provide various important services to ecosystem and environment. While, bats are well-known carrier of pathogenic viruses, their possible role as a potential carrier of pathogenic bacteria is under-explored. Here, using culture-based approach, employing multiple bacteriological media, over thousand bacteria were cultivated and identified from Rousettus leschenaultii (a frugivorous bat species), the majority of which were from the family Enterobacteriaceae and putative pathogens. Next, pathogenic potential of most frequently cultivated component of microbiome i.e. Escherichia coli was assessed to identify its known pathotypes which revealed the presence of virulent factors in many cultivated E. coli isolates. Applying in-depth bacterial community analysis using high-throughput 16 S rRNA gene sequencing, a high inter-individual variation was observed among the studied guano samples. Interestingly, a higher diversity of bacterial communities was observed in decaying guano representative. The search against human pathogenic bacteria database at 97% identity, a small proportion of sequences were found associated to well-known human pathogens. The present study thus indicates that this bat species may carry potential bacterial pathogens and advice to study the effect of these pathogens on bats itself and the probable mode of transmission to humans and other animals. PMID:27845426

Microbiome analysis reveals the abundance of bacterial pathogens in Rousettus leschenaultii guano.

PubMed

Banskar, Sunil; Bhute, Shrikant S; Suryavanshi, Mangesh V; Punekar, Sachin; Shouche, Yogesh S

2016-11-15

Bats are crucial for proper functioning of an ecosystem. They provide various important services to ecosystem and environment. While, bats are well-known carrier of pathogenic viruses, their possible role as a potential carrier of pathogenic bacteria is under-explored. Here, using culture-based approach, employing multiple bacteriological media, over thousand bacteria were cultivated and identified from Rousettus leschenaultii (a frugivorous bat species), the majority of which were from the family Enterobacteriaceae and putative pathogens. Next, pathogenic potential of most frequently cultivated component of microbiome i.e. Escherichia coli was assessed to identify its known pathotypes which revealed the presence of virulent factors in many cultivated E. coli isolates. Applying in-depth bacterial community analysis using high-throughput 16 S rRNA gene sequencing, a high inter-individual variation was observed among the studied guano samples. Interestingly, a higher diversity of bacterial communities was observed in decaying guano representative. The search against human pathogenic bacteria database at 97% identity, a small proportion of sequences were found associated to well-known human pathogens. The present study thus indicates that this bat species may carry potential bacterial pathogens and advice to study the effect of these pathogens on bats itself and the probable mode of transmission to humans and other animals.

Metabolic host responses to infection by intracellular bacterial pathogens

PubMed Central

Eisenreich, Wolfgang; Heesemann, Jürgen; Rudel, Thomas; Goebel, Werner

2013-01-01

The interaction of bacterial pathogens with mammalian hosts leads to a variety of physiological responses of the interacting partners aimed at an adaptation to the new situation. These responses include multiple metabolic changes in the affected host cells which are most obvious when the pathogen replicates within host cells as in case of intracellular bacterial pathogens. While the pathogen tries to deprive nutrients from the host cell, the host cell in return takes various metabolic countermeasures against the nutrient theft. During this conflicting interaction, the pathogen triggers metabolic host cell responses by means of common cell envelope components and specific virulence-associated factors. These host reactions generally promote replication of the pathogen. There is growing evidence that pathogen-specific factors may interfere in different ways with the complex regulatory network that controls the carbon and nitrogen metabolism of mammalian cells. The host cell defense answers include general metabolic reactions, like the generation of oxygen- and/or nitrogen-reactive species, and more specific measures aimed to prevent access to essential nutrients for the respective pathogen. Accurate results on metabolic host cell responses are often hampered by the use of cancer cell lines that already exhibit various de-regulated reactions in the primary carbon metabolism. Hence, there is an urgent need for cellular models that more closely reflect the in vivo infection conditions. The exact knowledge of the metabolic host cell responses may provide new interesting concepts for antibacterial therapies. PMID:23847769

Bacterial Co-infection in Hospitalized Children with Mycoplasma pneumoniae Pneumonia.

PubMed

Song, Qing; Xu, Bao-Ping; Shen, Kun-Ling

2016-10-08

To describe the frequency and impact of bacterial co-infections in children hospitalized with Mycoplasma pneumoniae pneumonia. Retrospective, descriptive study. Tertiary-care hospital in Beijing, China. 8612 children admitted to Beijing Childrens Hospital from June 2006 to June 2014. According to the testing results of etiology we divided the cases into pure M. pneumoniae infection group and mixed bacterial infection group. We analyzed clinical features, hospital expenses and differences between these two groups. 173 (2%) of included children had bacterial coinfection. 56.2% of bacterial pathogens were identified as Streptococcus pneumoniae. The most common bacterium causing co-infection in children with M. pneumoniae pneumonia was S. pneumoniae.

Peripheral ischaemic retinopathy and neovascularisation in a patient with subacute streptococcus mitis-induced bacterial endocarditis.

PubMed

Leysen, Laura S; Kreps, Elke O; De Schryver, Ilse; Hoornaert, Kristien P; Smith, Vanessa; De Zaeytijd, Julie

2017-01-01

Objective: To describe a patient with peripheral retinal ischaemia and neovascularisation who was diagnosed with streptococcus mitis-induced bacterial endocarditis. Methods: Retrospective analysis of case report. A 57-year-old man presented with a history of a rapidly progressive, bilateral, painless visual loss. He also suffered from pain in the neck and lower back and a weight loss of 10 kg. He underwent a full ophthalmologic work-up, laboratory investigations, and imaging of the spine. Results: BCVA was reduced to 20/40 in the right eye and 20/32 in the left eye. Fundoscopy showed rare intra-retinal haemorrhages including few Roth spots and cotton wool lesions. Fluorescein angiography demonstrated large areas of peripheral retinal ischaemia and neovascularisation. Imaging of the spine showed spondylodiscitis on several levels. Further imaging and blood cultures confirmed bacterial endocarditis of the mitral valve. Streptococcus mitis was subsequently identified as the causative organism. Conclusion: Peripheral retinal ischaemia and neovascularisation were previously unrecognised as a feature of infectious endocarditis. Therefore, their presence, apart from the classic Roth spots, should prompt the consideration of infectious endocarditis in the etiologic work-up.

Peripheral ischaemic retinopathy and neovascularisation in a patient with subacute streptococcus mitis-induced bacterial endocarditis

PubMed Central

Leysen, Laura S.; Kreps, Elke O.; De Schryver, Ilse; Hoornaert, Kristien P.; Smith, Vanessa; De Zaeytijd, Julie

2017-01-01

Objective: To describe a patient with peripheral retinal ischaemia and neovascularisation who was diagnosed with streptococcus mitis-induced bacterial endocarditis. Methods: Retrospective analysis of case report. A 57-year-old man presented with a history of a rapidly progressive, bilateral, painless visual loss. He also suffered from pain in the neck and lower back and a weight loss of 10 kg. He underwent a full ophthalmologic work-up, laboratory investigations, and imaging of the spine. Results: BCVA was reduced to 20/40 in the right eye and 20/32 in the left eye. Fundoscopy showed rare intra-retinal haemorrhages including few Roth spots and cotton wool lesions. Fluorescein angiography demonstrated large areas of peripheral retinal ischaemia and neovascularisation. Imaging of the spine showed spondylodiscitis on several levels. Further imaging and blood cultures confirmed bacterial endocarditis of the mitral valve. Streptococcus mitis was subsequently identified as the causative organism. Conclusion: Peripheral retinal ischaemia and neovascularisation were previously unrecognised as a feature of infectious endocarditis. Therefore, their presence, apart from the classic Roth spots, should prompt the consideration of infectious endocarditis in the etiologic work-up. PMID:28944156

Molecular and genomic characterization of pathogenic traits of group A Streptococcus pyogenes

PubMed Central

HAMADA, Shigeyuki; KAWABATA, Shigetada; NAKAGAWA, Ichiro

2015-01-01

Group A streptococcus (GAS) or Streptococcus pyogenes causes various diseases ranging from self-limiting sore throat to deadly invasive diseases. The genome size of GAS is 1.85–1.9 Mb, and genomic rearrangement has been demonstrated. GAS possesses various surface-associated substances such as hyaluronic capsule, M proteins, and fibronectin/laminin/immunoglobulin-binding proteins. These are related to the virulence and play multifaceted and mutually reflected roles in the pathogenesis of GAS infections. Invasion of GAS into epithelial cells and deeper tissues provokes immune and non-immune defense or inflammatory responses including the recruitment of neutrophils, macrophages, and dendritic cells in hosts. GAS frequently evades host defense mechanisms by using its virulence factors. Extracellular products of GAS may perturb cellular and subcellular functions and degrade tissues enzymatically, which leads to the aggravation of local and/or systemic disorders in the host. In this review, we summarize some important cellular and extracellular substances that may affect pathogenic processes during GAS infections, and the host responses to these. PMID:26666305

Kill rate of mastitis pathogens by a combination of cefalexin and kanamycin.

PubMed

Maneke, E; Pridmore, A; Goby, L; Lang, I

2011-01-01

To assess the bacterial killing rate produced by a combination of cefalexin and kanamycin at two different concentration ratios. Time-kill kinetics of cefalexin and kanamycin, individually and in combination, were determined against one strain each of Escherichia coli, Staphylococcus aureus, Streptococcus agalactiae, Streptococcus dysgalactiae and Streptococcus uberis. The combination was tested using two fixed ratios (cefalexin : kanamycin ratios of 1·25 : 1 and 1 : 2·3) and two concentrations of each ratio. Time-kill curves produced with either ratio were quite similar. Against most bacterial species, higher concentrations produced faster kill. In all cases, the combination of cefalexin and kanamycin showed faster and greater kill at lower antibiotic concentrations than those observed with either drug alone. The combination of cefalexin and kanamycin results in a fast initial killing of major mastitis pathogens at both concentration ratios. The combination of cefalexin and kanamycin achieved rapid bacterial kill at concentrations and ratios that can be achieved in vivo following intramammary infusion of a mastitis treatment. © 2010 Boehringer Ingelheim Vetmedica GmbH. Journal of Applied Microbiology © 2010 The Society for Applied Microbiology.

Prophage Lysin Ply30 Protects Mice from Streptococcus suis and Streptococcus equi subsp. zooepidemicus Infections

PubMed Central

Tang, Fang; Li, Dezhi; Wang, Haojin; Ma, Zhe; Lu, Chengping

2015-01-01

Streptococcus suis and Streptococcus equi subsp. zooepidemicus are capable of infecting humans and various animals, causing significant problems for the worldwide swine industry. As antibiotic resistance has increased, lysosomal enzymes encoded by phages have shown potential for use against pathogenic bacteria. In this study, a novel bacteriophage lysin, Ply30, encoded by the S. suis prophage phi30c, was recombinantly expressed and purified. Ply30 showed high bacteriolysis activity on S. suis and S. equi subsp. zooepidemicus in vitro. The ratio of the optical density at 600 nm (OD600) with treatment versus the OD600 with no treatment for most tested S. suis and S. equi subsp. zooepidemicus strains decreased from 1 to <0.3 and <0.5, respectively, within 1 h. The results of plate viability assays showed that treated bacteria suffered a 1- to 2-log decrease in CFU within 1 h. The optimal concentration of Ply30 was 50 μg/ml, and the optimal pH was 7. Moreover, Ply30 maintained high activity over a wide pH range (pH 6 to 10). The MICs of Ply30 against Streptococcus strains ranged from 16 to 512 μg/ml. In vivo, a 2-mg dose of Ply30 protected 90% (9/10 mice) of mice from infection with S. equi subsp. zooepidemicus and 80% (8/10 mice) of mice from infection with S. suis. Seven days after lysin Ply30 treatment, bacterial loads were significantly decreased in all tested organs and blood compared with those at 1 h postinfection without Ply30 treatment. Ply30 showed in vitro and in vivo antimicrobial efficiency and protected mice against two kinds of bacterial infections, indicating that Ply30 may be an effective therapeutic against streptococci. PMID:26253669

Prophage lysin Ply30 protects mice from Streptococcus suis and Streptococcus equi subsp. zooepidemicus infections.

PubMed

Tang, Fang; Li, Dezhi; Wang, Haojin; Ma, Zhe; Lu, Chengping; Dai, Jianjun

2015-11-01

Streptococcus suis and Streptococcus equi subsp. zooepidemicus are capable of infecting humans and various animals, causing significant problems for the worldwide swine industry. As antibiotic resistance has increased, lysosomal enzymes encoded by phages have shown potential for use against pathogenic bacteria. In this study, a novel bacteriophage lysin, Ply30, encoded by the S. suis prophage phi30c, was recombinantly expressed and purified. Ply30 showed high bacteriolysis activity on S. suis and S. equi subsp. zooepidemicus in vitro. The ratio of the optical density at 600 nm (OD600) with treatment versus the OD600 with no treatment for most tested S. suis and S. equi subsp. zooepidemicus strains decreased from 1 to <0.3 and <0.5, respectively, within 1 h. The results of plate viability assays showed that treated bacteria suffered a 1- to 2-log decrease in CFU within 1 h. The optimal concentration of Ply30 was 50 μg/ml, and the optimal pH was 7. Moreover, Ply30 maintained high activity over a wide pH range (pH 6 to 10). The MICs of Ply30 against Streptococcus strains ranged from 16 to 512 μg/ml. In vivo, a 2-mg dose of Ply30 protected 90% (9/10 mice) of mice from infection with S. equi subsp. zooepidemicus and 80% (8/10 mice) of mice from infection with S. suis. Seven days after lysin Ply30 treatment, bacterial loads were significantly decreased in all tested organs and blood compared with those at 1 h postinfection without Ply30 treatment. Ply30 showed in vitro and in vivo antimicrobial efficiency and protected mice against two kinds of bacterial infections, indicating that Ply30 may be an effective therapeutic against streptococci. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

O Antigen Modulates Insect Vector Acquisition of the Bacterial Plant Pathogen Xylella fastidiosa

PubMed Central

Rapicavoli, Jeannette N.; Kinsinger, Nichola; Perring, Thomas M.; Backus, Elaine A.; Shugart, Holly J.; Walker, Sharon

2015-01-01

Hemipteran insect vectors transmit the majority of plant pathogens. Acquisition of pathogenic bacteria by these piercing/sucking insects requires intimate associations between the bacterial cells and insect surfaces. Lipopolysaccharide (LPS) is the predominant macromolecule displayed on the cell surface of Gram-negative bacteria and thus mediates bacterial interactions with the environment and potential hosts. We hypothesized that bacterial cell surface properties mediated by LPS would be important in modulating vector-pathogen interactions required for acquisition of the bacterial plant pathogen Xylella fastidiosa, the causative agent of Pierce's disease of grapevines. Utilizing a mutant that produces truncated O antigen (the terminal portion of the LPS molecule), we present results that link this LPS structural alteration to a significant decrease in the attachment of X. fastidiosa to blue-green sharpshooter foreguts. Scanning electron microscopy confirmed that this defect in initial attachment compromised subsequent biofilm formation within vector foreguts, thus impairing pathogen acquisition. We also establish a relationship between O antigen truncation and significant changes in the physiochemical properties of the cell, which in turn affect the dynamics of X. fastidiosa adhesion to the vector foregut. Lastly, we couple measurements of the physiochemical properties of the cell with hydrodynamic fluid shear rates to produce a Comsol model that predicts primary areas of bacterial colonization within blue-green sharpshooter foreguts, and we present experimental data that support the model. These results demonstrate that, in addition to reported protein adhesin-ligand interactions, O antigen is crucial for vector-pathogen interactions, specifically in the acquisition of this destructive agricultural pathogen. PMID:26386068

Comparative genomics of the dairy isolate Streptococcus macedonicus ACA-DC 198 against related members of the Streptococcus bovis/Streptococcus equinus complex

PubMed Central

2014-01-01

Background Within the genus Streptococcus, only Streptococcus thermophilus is used as a starter culture in food fermentations. Streptococcus macedonicus though, which belongs to the Streptococcus bovis/Streptococcus equinus complex (SBSEC), is also frequently isolated from fermented foods mainly of dairy origin. Members of the SBSEC have been implicated in human endocarditis and colon cancer. Here we compare the genome sequence of the dairy isolate S. macedonicus ACA-DC 198 to the other SBSEC genomes in order to assess in silico its potential adaptation to milk and its pathogenicity status. Results Despite the fact that the SBSEC species were found tightly related based on whole genome phylogeny of streptococci, two distinct patterns of evolution were identified among them. Streptococcus macedonicus, Streptococcus infantarius CJ18 and Streptococcus pasteurianus ATCC 43144 seem to have undergone reductive evolution resulting in significantly diminished genome sizes and increased percentages of potential pseudogenes when compared to Streptococcus gallolyticus subsp. gallolyticus. In addition, the three species seem to have lost genes for catabolizing complex plant carbohydrates and for detoxifying toxic substances previously linked to the ability of S. gallolyticus to survive in the rumen. Analysis of the S. macedonicus genome revealed features that could support adaptation to milk, including an extra gene cluster for lactose and galactose metabolism, a proteolytic system for casein hydrolysis, auxotrophy for several vitamins, an increased ability to resist bacteriophages and horizontal gene transfer events with the dairy Lactococcus lactis and S. thermophilus as potential donors. In addition, S. macedonicus lacks several pathogenicity-related genes found in S. gallolyticus. For example, S. macedonicus has retained only one (i.e. the pil3) of the three pilus gene clusters which may mediate the binding of S. gallolyticus to the extracellular matrix. Unexpectedly

Comparative genomics of the dairy isolate Streptococcus macedonicus ACA-DC 198 against related members of the Streptococcus bovis/Streptococcus equinus complex.

PubMed

Papadimitriou, Konstantinos; Anastasiou, Rania; Mavrogonatou, Eleni; Blom, Jochen; Papandreou, Nikos C; Hamodrakas, Stavros J; Ferreira, Stéphanie; Renault, Pierre; Supply, Philip; Pot, Bruno; Tsakalidou, Effie

2014-04-08

Within the genus Streptococcus, only Streptococcus thermophilus is used as a starter culture in food fermentations. Streptococcus macedonicus though, which belongs to the Streptococcus bovis/Streptococcus equinus complex (SBSEC), is also frequently isolated from fermented foods mainly of dairy origin. Members of the SBSEC have been implicated in human endocarditis and colon cancer. Here we compare the genome sequence of the dairy isolate S. macedonicus ACA-DC 198 to the other SBSEC genomes in order to assess in silico its potential adaptation to milk and its pathogenicity status. Despite the fact that the SBSEC species were found tightly related based on whole genome phylogeny of streptococci, two distinct patterns of evolution were identified among them. Streptococcus macedonicus, Streptococcus infantarius CJ18 and Streptococcus pasteurianus ATCC 43144 seem to have undergone reductive evolution resulting in significantly diminished genome sizes and increased percentages of potential pseudogenes when compared to Streptococcus gallolyticus subsp. gallolyticus. In addition, the three species seem to have lost genes for catabolizing complex plant carbohydrates and for detoxifying toxic substances previously linked to the ability of S. gallolyticus to survive in the rumen. Analysis of the S. macedonicus genome revealed features that could support adaptation to milk, including an extra gene cluster for lactose and galactose metabolism, a proteolytic system for casein hydrolysis, auxotrophy for several vitamins, an increased ability to resist bacteriophages and horizontal gene transfer events with the dairy Lactococcus lactis and S. thermophilus as potential donors. In addition, S. macedonicus lacks several pathogenicity-related genes found in S. gallolyticus. For example, S. macedonicus has retained only one (i.e. the pil3) of the three pilus gene clusters which may mediate the binding of S. gallolyticus to the extracellular matrix. Unexpectedly, similar findings were

Within-host evolution decreases virulence in an opportunistic bacterial pathogen.

PubMed

Mikonranta, Lauri; Mappes, Johanna; Laakso, Jouni; Ketola, Tarmo

2015-08-19

Pathogens evolve in a close antagonistic relationship with their hosts. The conventional theory proposes that evolution of virulence is highly dependent on the efficiency of direct host-to-host transmission. Many opportunistic pathogens, however, are not strictly dependent on the hosts due to their ability to reproduce in the free-living environment. Therefore it is likely that conflicting selection pressures for growth and survival outside versus within the host, rather than transmission potential, shape the evolution of virulence in opportunists. We tested the role of within-host selection in evolution of virulence by letting a pathogen Serratia marcescens db11 sequentially infect Drosophila melanogaster hosts and then compared the virulence to strains that evolved only in the outside-host environment. We found that the pathogen adapted to both Drosophila melanogaster host and novel outside-host environment, leading to rapid evolutionary changes in the bacterial life-history traits including motility, in vitro growth rate, biomass yield, and secretion of extracellular proteases. Most significantly, selection within the host led to decreased virulence without decreased bacterial load while the selection lines in the outside-host environment maintained the same level of virulence with ancestral bacteria. This experimental evidence supports the idea that increased virulence is not an inevitable consequence of within-host adaptation even when the epidemiological restrictions are removed. Evolution of attenuated virulence could occur because of immune evasion within the host. Alternatively, rapid fluctuation between outside-host and within-host environments, which is typical for the life cycle of opportunistic bacterial pathogens, could lead to trade-offs that lower pathogen virulence.

Influence of fluoride on the bacterial composition of a dual-species biofilm composed of Streptococcus mutans and Streptococcus oralis.

PubMed

Jung, Ji-Eun; Cai, Jian-Na; Cho, Sung-Dae; Song, Kwang-Yeob; Jeon, Jae-Gyu

2016-10-01

Despite the widespread use of fluoride for the prevention of dental caries, few studies have demonstrated the effects of fluoride on the bacterial composition of dental biofilms. This study investigated whether fluoride affects the proportion of Streptococcus mutans and S. oralis in mono- and dual-species biofilm models, via microbiological, biochemical, and confocal fluorescence microscope studies. Fluoride did not affect the bacterial count and bio-volume of S. mutans and S. oralis in mono-species biofilms, except for the 24-h-old S. mutans biofilms. However, fluoride reduced the proportion and bio-volume of S. mutans but did not decrease those of S. oralis during both S. oralis and S. mutans dual-species biofilm formation, which may be related to the decrease in extracellular polysaccharide formation by fluoride. These results suggest that fluoride may prevent the shift in the microbial proportion to cariogenic bacteria in dental biofilms, subsequently inhibiting the cariogenic bacteria dominant biofilm formation.

The effect of bacterial environmental and metabolic stresses on a laser-induced breakdown spectroscopy (LIBS) based identification of Escherichia coli and Streptococcus viridans.

PubMed

Mohaidat, Qassem; Palchaudhuri, Sunil; Rehse, Steven J

2011-04-01

In this paper we investigate the effect that adverse environmental and metabolic stresses have on the laser-induced breakdown spectroscopy (LIBS) identification of bacterial specimens. Single-pulse LIBS spectra were acquired from a non-pathogenic strain of Escherichia coli cultured in two different nutrient media: a trypticase soy agar and a MacConkey agar with a 0.01% concentration of deoxycholate. A chemometric discriminant function analysis showed that the LIBS spectra acquired from bacteria grown in these two media were indistinguishable and easily discriminated from spectra acquired from two other non-pathogenic E. coli strains. LIBS spectra were obtained from specimens of a nonpathogenic E. coli strain and an avirulent derivative of the pathogen Streptococcus viridans in three different metabolic situations: live bacteria reproducing in the log-phase, bacteria inactivated on an abiotic surface by exposure to bactericidal ultraviolet irradiation, and bacteria killed via autoclaving. All bacteria were correctly identified regardless of their metabolic state. This successful identification suggests the possibility of testing specimens that have been rendered safe for handling prior to LIBS identification. This would greatly enhance personnel safety and lower the cost of a LIBS-based diagnostic test. LIBS spectra were obtained from pathogenic and non-pathogenic bacteria that were deprived of nutrition for a period of time ranging from one day to nine days by deposition on an abiotic surface at room temperature. All specimens were successfully classified by species regardless of the duration of nutrient deprivation. © 2011 Society for Applied Spectroscopy

Genomics, evolution, and molecular epidemiology of the Streptococcus bovis/Streptococcus equinus complex (SBSEC).

PubMed

Jans, Christoph; Meile, Leo; Lacroix, Christophe; Stevens, Marc J A

2015-07-01

The Streptococcus bovis/Streptococcus equinus complex (SBSEC) is a group of human and animal derived streptococci that are commensals (rumen and gastrointestinal tract), opportunistic pathogens or food fermentation associates. The classification of SBSEC has undergone massive changes and currently comprises 7 (sub)species grouped into four branches based on sequences identities: the Streptococcus gallolyticus, the Streptococcus equinus, the Streptococcus infantarius and the Streptococcus alactolyticus branch. In animals, SBSEC are causative agents for ruminal acidosis, potentially laminitis and infective endocarditis (IE). In humans, a strong association was established between bacteraemia, IE and colorectal cancer. Especially the SBSEC-species S. gallolyticus subsp. gallolyticus is an emerging pathogen for IE and prosthetic joint infections. S. gallolyticus subsp. pasteurianus and the S. infantarius branch are further associated with biliary and urinary tract infections. Knowledge on pathogenic mechanisms is so far limited to colonization factors such as pili and biofilm formation. Certain strain variants of S. gallolyticus subsp. macedonicus and S. infantarius subsp. infantarius are associated with traditional dairy and plant-based food fermentations and display traits suggesting safety. However, due to their close relationship to virulent strains, their use in food fermentation has to be critically assessed. Additionally, implementing accurate and up-to-date taxonomy is critical to enable appropriate treatment of patients and risk assessment of species and strains via recently developed multilocus sequence typing schemes to enable comparative global epidemiology. Comparative genomics revealed that SBSEC strains harbour genomics islands (GI) that seem acquired from other streptococci by horizontal gene transfer. In case of virulent strains these GI frequently encode putative virulence factors, in strains from food fermentation the GI encode functions that are

Molecular assessment of bacterial pathogens - a contribution to drinking water safety.

PubMed

Brettar, Ingrid; Höfle, Manfred G

2008-06-01

Human bacterial pathogens are considered as an increasing threat to drinking water supplies worldwide because of the growing demand of high-quality drinking water and the decreasing quality and quantity of available raw water. Moreover, a negative impact of climate change on freshwater resources is expected. Recent advances in molecular detection technologies for bacterial pathogens in drinking water bear the promise in improving the safety of drinking water supplies by precise detection and identification of the pathogens. More importantly, the array of molecular approaches allows understanding details of infection routes of waterborne diseases, the effects of changes in drinking water treatment, and management of freshwater resources.

[Influence of human gastrointestinal tract bacterial pathogens on host cell apoptosis].

PubMed

Wronowska, Weronika; Godlewska, Renata; Jagusztyn-Krynicka, Elzbieta Katarzyna

2005-01-01

Several pathogenic bacteria are able to trigger apoptosis in the host cell, but the mechanisms by which it occurs differ, and the resulting pathology can take different courses. Induction and/or blockage of programmed cell death upon infection is a result of complex interaction of bacterial proteins with cellular proteins involved in signal transduction and apoptosis. In this review we focus on pro/anti-apoptotic activities exhibited by two enteric pathogens Salmonella enterica, Yersinia spp. and gastric pathogen Helicobacter pylori. We present current knowledge on how interaction between mammalian and bacterial cell relates to the molecular pathways of apoptosis, and what is the role of apoptosis in pathogenesis.

Adhesion of bacterial pathogens to soil colloidal particles: influences of cell type, natural organic matter, and solution chemistry.

PubMed

Zhao, Wenqiang; Walker, Sharon L; Huang, Qiaoyun; Cai, Peng

2014-04-15

Bacterial adhesion to granular soil particles is well studied; however, pathogen interactions with naturally occurring colloidal particles (<2 μm) in soil has not been investigated. This study was developed to identify the interaction mechanisms between model bacterial pathogens and soil colloids as a function of cell type, natural organic matter (NOM), and solution chemistry. Specifically, batch adhesion experiments were conducted using NOM-present, NOM-stripped soil colloids, Streptococcus suis SC05 and Escherichia coli WH09 over a wide range of solution pH (4.0-9.0) and ionic strength (IS, 1-100 mM KCl). Cell characterization techniques, Freundlich isotherm, and Derjaguin-Landau-Verwey-Overbeek (DLVO) theory (sphere-sphere model) were utilized to quantitatively determine the interactions between cells and colloids. The adhesion coefficients (Kf) of S. suis SC05 to NOM-present and NOM-stripped soil colloids were significantly higher than E. coli WH09, respectively. Similarly, Kf values of S. suis SC05 and E. coli WH09 adhesion to NOM-stripped soil colloids were greater than those colloids with NOM-present, respectively, suggesting NOM inhibits bacterial adhesion. Cell adhesion to soil colloids declined with increasing pH and enhanced with rising IS (1-50 mM). Interaction energy calculations indicate these adhesion trends can be explained by DLVO-type forces, with S. suis SC05 and E. coli WH09 being weakly adhered in shallow secondary energy minima via polymer bridging and charge heterogeneity. S. suis SC05 adhesion decreased at higher IS 100 mM, which is attributed to the change of hydrophobic effect and steric repulsion resulted from the greater presence of extracellular polymeric substances (EPS) on S. suis SC05 surface as compared to E. coli WH09. Hence, pathogen adhesion to the colloidal material is determined by a combination of DLVO, charge heterogeneity, hydrophobic and polymer interactions as a function of solution chemistry. Copyright © 2014 Elsevier

Pathogen espionage: multiple bacterial adrenergic sensors eavesdrop on host communication systems.

PubMed

Karavolos, Michail H; Winzer, Klaus; Williams, Paul; Khan, C M Anjam

2013-02-01

The interactions between bacterial pathogens and their eukaryotic hosts are vital in determining the outcome of infections. Bacterial pathogens employ molecular sensors to detect and facilitate adaptation to changes in their niche. The sensing of these extracellular signals enables the pathogen to navigate within mammalian hosts. Intercellular bacterial communication is facilitated by the production and sensing of autoinducer (AI) molecules via quorum sensing. More recently, AI-3 and the host neuroendocrine (NE) hormones adrenaline and noradrenaline were reported to display cross-talk for the activation of the same signalling pathways. Remarkably, there is increasing evidence to suggest that enteric bacteria sense and respond to the host NE stress hormones adrenaline and noradrenaline to modulate virulence. These responses can be inhibited by α and β-adrenergic receptor antagonists implying a bacterial receptor-based sensing and signalling cascade. In Escherichia coli O157:H7 and Salmonella, QseC has been proposed as the adrenergic receptor. Strikingly, there is an increasing body of evidence that not all the bacterial adrenergic responses require signalling through QseC. Here we provide additional hypotheses to reconcile these observations implicating the existence of alternative adrenergic receptors including BasS, QseE and CpxA and their associated signalling cascades with major roles in interkingdom communication. © 2012 Blackwell Publishing Ltd.

Immunoelectrophoretic study of cell surface antigens from different Streptococcus mutans serotypes and Streptococcus sanguis.

PubMed

Ogier, J A; Klein, J P; Niddam, R; Frank, R M

1985-06-01

Antigens prepared from culture supernatants or whole cells of several cariogenic strains were examined by immunoelectrophoresis for their crossed antigenicity, with reference to Streptococcus mutans OMZ175, serotype f. Crossed immunoelectrophoresis revealed a crossreactivity between soluble extracellular and wall associated antigens of six strains of Streptococcus mutans and one strain of Streptococcus sanguis. Protease destroyed the immunoreactivity of crossreactive antigens. One of them was shown to be localized on the bacterial surface.

Capsular Sialyltransferase Specificity Mediates Different Phenotypes in Streptococcus suis and Group B Streptococcus

PubMed Central

Roy, David; Takamatsu, Daisuke; Okura, Masatoshi; Goyette-Desjardins, Guillaume; Van Calsteren, Marie-Rose; Dumesnil, Audrey; Gottschalk, Marcelo; Segura, Mariela

2018-01-01

The capsular polysaccharide (CPS) represents a key virulence factor for most encapsulated streptococci. Streptococcus suis and Group B Streptococcus (GBS) are both well-encapsulated pathogens of clinical importance in veterinary and/or human medicine and responsible for invasive systemic diseases. S. suis and GBS are the only Gram-positive bacteria which express a sialylated CPS at their surface. An important difference between these two sialylated CPSs is the linkage between the side-chain terminal galactose and sialic acid, being α-2,6 for S. suis but α-2,3 for GBS. It is still unclear how sialic acid may affect CPS production and, consequently, the pathogenesis of the disease caused by these two bacterial pathogens. Here, we investigated the role of sialic acid and the putative effect of sialic acid linkage modification in CPS synthesis using inter-species allelic exchange mutagenesis. To this aim, a new molecular biogenetic approach to express CPS with modified sialic acid linkage was developed. We showed that sialic acid (and its α-2,6 linkage) is crucial for S. suis CPS synthesis, whereas for GBS, CPS synthesis may occur in presence of an α-2,6 sialyltransferase or in absence of sialic acid moiety. To evaluate the effect of the CPS composition/structure on sialyltransferase activity, two distinct capsular serotypes within each bacterial species were compared (S. suis serotypes 2 and 14 and GBS serotypes III and V). It was demonstrated that the observed differences in sialyltransferase activity and specificity between S. suis and GBS were serotype unrestricted. This is the first time that a study investigates the interspecies exchange of capsular sialyltransferase genes in Gram-positive bacteria. The obtained mutants represent novel tools that could be used to further investigate the immunomodulatory properties of sialylated CPSs. Finally, in spite of common CPS structural characteristics and similarities in the cps loci, sialic acid exerts differential

Microbial minimalism: genome reduction in bacterial pathogens.

PubMed

Moran, Nancy A

2002-03-08

When bacterial lineages make the transition from free-living or facultatively parasitic life cycles to permanent associations with hosts, they undergo a major loss of genes and DNA. Complete genome sequences are providing an understanding of how extreme genome reduction affects evolutionary directions and metabolic capabilities of obligate pathogens and symbionts.

Direct detection of various pathogens by loop-mediated isothermal amplification assays on bacterial culture and bacterial colony.

PubMed

Yan, Muxia; Li, Weidong; Zhou, Zhenwen; Peng, Hongxia; Luo, Ziyan; Xu, Ling

2017-01-01

In this work, loop-mediated isothermal amplification based detection assay using bacterial culture and bacterial colony for various common pathogens direct detection had been established, evaluated and further applied. A total of five species of common pathogens and nine detection targets (tlh, tdh and trh for V. Parahaemolyticus, rfbE, stx1 and stx2 for E. coli, oprI for P. aeruginosa, invA for Salmonella and hylA for L. monocytogenes) were performed on bacterial culture and bacterial colony LAMP. To evaluate and optimize this assay, a total of 116 standard strains were included. Then, for each detected targets, 20 random selected strains were applied. Results were determined through both visual observation of the changed color by naked eye and electrophoresis, which increased the accuracy of survey. The minimum adding quantity of each primer had been confirmed, and the optimal amplification was obtained under 65 °C for 45 min with 25 μl reaction volume. The detection limit of bacterial culture LAMP and PCR assay were determined to be 10 2 and 10 4 or 10 5  CFU/reaction, respectively. No false positive amplification was observed when subjecting the bacterial -LAMP assay to 116 reference strains. This was the first report of colony-LAMP and culture-LAMP assay, which had been demonstrated to be a fast, reliable, cost-effective and simple method on detection of various common pathogens. Copyright © 2016 Elsevier Ltd. All rights reserved.

Encyclopedia of bacterial gene circuits whose presence or absence correlate with pathogenicity--a large-scale system analysis of decoded bacterial genomes.

PubMed

Shestov, Maksim; Ontañón, Santiago; Tozeren, Aydin

2015-10-13

Bacterial infections comprise a global health challenge as the incidences of antibiotic resistance increase. Pathogenic potential of bacteria has been shown to be context dependent, varying in response to environment and even within the strains of the same genus. We used the KEGG repository and extensive literature searches to identify among the 2527 bacterial genomes in the literature those implicated as pathogenic to the host, including those which show pathogenicity in a context dependent manner. Using data on the gene contents of these genomes, we identified sets of genes highly abundant in pathogenic but relatively absent in commensal strains and vice versa. In addition, we carried out genome comparison within a genus for the seventeen largest genera in our genome collection. We projected the resultant lists of ortholog genes onto KEGG bacterial pathways to identify clusters and circuits, which can be linked to either pathogenicity or synergy. Gene circuits relatively abundant in nonpathogenic bacteria often mediated biosynthesis of antibiotics. Other synergy-linked circuits reduced drug-induced toxicity. Pathogen-abundant gene circuits included modules in one-carbon folate, two-component system, type-3 secretion system, and peptidoglycan biosynthesis. Antibiotics-resistant bacterial strains possessed genes modulating phagocytosis, vesicle trafficking, cytoskeletal reorganization, and regulation of the inflammatory response. Our study also identified bacterial genera containing a circuit, elements of which were previously linked to Alzheimer's disease. Present study produces for the first time, a signature, in the form of a robust list of gene circuitry whose presence or absence could potentially define the pathogenicity of a microbiome. Extensive literature search substantiated a bulk majority of the commensal and pathogenic circuitry in our predicted list. Scanning microbiome libraries for these circuitry motifs will provide further insights into the complex

Periorbital Necrotizing Fasciitis Secondary to Candida parapsilosis and Streptococcus pyogenes.

PubMed

Zhang, Matthew; Chelnis, James; Mawn, Louise A

Necrotizing fasciitis is most often caused by either polymicrobial bacterial infections or by Gram-positive organisms, such as Streptococcus or Staphylococcus; however, rare cases of fungal necrotizing fasciitis have been reported. Candida parapsilosis is an emerging fungal pathogen. This fungus grows in either a yeast or pseudohyphal form. C. parapsilosis has been reported to cause keratitis, intraocular infection, and seeding of frontalis slings. C. parapsilosis is a commensal of human skin and can be acquired by nosocomial spread. Necrotizing fasciitis due to Candida has rarely been reported, but to date C. parapsilosis has not been identified as the causative organism in necrotizing fasciitis. This is the first documented case of human periocular soft tissue infection by C. parapsilosis, and also the first report providing evidence of mycotic infection in a necrotizing fasciitis concurrently infected by Streptococcus pyogenes.

Streptococcus tangierensis sp. nov. and Streptococcus cameli sp. nov., two novel Streptococcus species isolated from raw camel milk in Morocco.

PubMed

Kadri, Zaina; Vandamme, Peter; Ouadghiri, Mouna; Cnockaert, Margo; Aerts, Maarten; Elfahime, El Mostafa; Farricha, Omar El; Swings, Jean; Amar, Mohamed

2015-02-01

Biochemical and molecular genetic studies were performed on two unidentified Gram-stain positive, catalase and oxidase negative, non-hemolytic Streptococcus-like organisms recovered from raw camel milk in Morocco. Phenotypic characterization and comparative 16S rRNA gene sequencing demonstrated that the two strains were highly different from each other and that they did not correspond to any recognized species of the genus Streptococcus. Phylogenetic analysis based on 16S rRNA gene sequences showed the unidentified organisms each formed a hitherto unknown sub-line within the genus Streptococcus, displaying a close affinity with Streptococcus moroccensis, Streptococcus minor and Streptococcus ovis. DNA G+C content determination, MALDI-TOF mass spectrometry and biochemical tests demonstrated the bacterial isolates represent two novel species. Based on the phenotypic distinctiveness of the new bacteria and molecular genetic evidence, it is proposed to classify the two strains as Streptococcus tangierensis sp. nov., with CCMM B832(T) (=LMG 27683(T)) as the type strain, and Streptococcus cameli sp. nov., with CCMM B834(T) (=LMG 27685(T)) as the type strain.

Structural and Functional Analysis of Cell Wall-anchored Polypeptide Adhesin BspA in Streptococcus agalactiae*

PubMed Central

Rego, Sara; Heal, Timothy J.; Pidwill, Grace R.; Till, Marisa; Robson, Alice; Lamont, Richard J.; Sessions, Richard B.; Jenkinson, Howard F.; Race, Paul R.; Nobbs, Angela H.

2016-01-01

Streptococcus agalactiae (group B Streptococcus, GBS) is the predominant cause of early-onset infectious disease in neonates and is responsible for life-threatening infections in elderly and immunocompromised individuals. Clinical manifestations of GBS infection include sepsis, pneumonia, and meningitis. Here, we describe BspA, a deviant antigen I/II family polypeptide that confers adhesive properties linked to pathogenesis in GBS. Heterologous expression of BspA on the surface of the non-adherent bacterium Lactococcus lactis confers adherence to scavenger receptor gp340, human vaginal epithelium, and to the fungus Candida albicans. Complementary crystallographic and biophysical characterization of BspA reveal a novel β-sandwich adhesion domain and unique asparagine-dependent super-helical stalk. Collectively, these findings establish a new bacterial adhesin structure that has in effect been hijacked by a pathogenic Streptococcus species to provide competitive advantage in human mucosal infections. PMID:27311712

O antigen modulates insect vector acquisition of the bacterial plant pathogen Xylella fastidiosa.

PubMed

Rapicavoli, Jeannette N; Kinsinger, Nichola; Perring, Thomas M; Backus, Elaine A; Shugart, Holly J; Walker, Sharon; Roper, M Caroline

2015-12-01

Hemipteran insect vectors transmit the majority of plant pathogens. Acquisition of pathogenic bacteria by these piercing/sucking insects requires intimate associations between the bacterial cells and insect surfaces. Lipopolysaccharide (LPS) is the predominant macromolecule displayed on the cell surface of Gram-negative bacteria and thus mediates bacterial interactions with the environment and potential hosts. We hypothesized that bacterial cell surface properties mediated by LPS would be important in modulating vector-pathogen interactions required for acquisition of the bacterial plant pathogen Xylella fastidiosa, the causative agent of Pierce's disease of grapevines. Utilizing a mutant that produces truncated O antigen (the terminal portion of the LPS molecule), we present results that link this LPS structural alteration to a significant decrease in the attachment of X. fastidiosa to blue-green sharpshooter foreguts. Scanning electron microscopy confirmed that this defect in initial attachment compromised subsequent biofilm formation within vector foreguts, thus impairing pathogen acquisition. We also establish a relationship between O antigen truncation and significant changes in the physiochemical properties of the cell, which in turn affect the dynamics of X. fastidiosa adhesion to the vector foregut. Lastly, we couple measurements of the physiochemical properties of the cell with hydrodynamic fluid shear rates to produce a Comsol model that predicts primary areas of bacterial colonization within blue-green sharpshooter foreguts, and we present experimental data that support the model. These results demonstrate that, in addition to reported protein adhesin-ligand interactions, O antigen is crucial for vector-pathogen interactions, specifically in the acquisition of this destructive agricultural pathogen. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Beyond Streptococcus mutans: Dental Caries Onset Linked to Multiple Species by 16S rRNA Community Analysis

PubMed Central

Gross, Erin L.; Beall, Clifford J.; Kutsch, Stacey R.; Firestone, Noah D.; Leys, Eugene J.; Griffen, Ann L.

2012-01-01

Dental caries in very young children may be severe, result in serious infection, and require general anesthesia for treatment. Dental caries results from a shift within the biofilm community specific to the tooth surface, and acidogenic species are responsible for caries. Streptococcus mutans, the most common acid producer in caries, is not always present and occurs as part of a complex microbial community. Understanding the degree to which multiple acidogenic species provide functional redundancy and resilience to caries-associated communities will be important for developing biologic interventions. In addition, microbial community interactions in health and caries pathogenesis are not well understood. The purpose of this study was to investigate bacterial community profiles associated with the onset of caries in the primary dentition. In a combination cross-sectional and longitudinal design, bacterial community profiles at progressive stages of caries and over time were examined and compared to those of health. 16S rRNA gene sequencing was used for bacterial community analysis. Streptococcus mutans was the dominant species in many, but not all, subjects with caries. Elevated levels of S. salivarius, S. sobrinus, and S. parasanguinis were also associated with caries, especially in subjects with no or low levels of S. mutans, suggesting these species are alternative pathogens, and that multiple species may need to be targeted for interventions. Veillonella, which metabolizes lactate, was associated with caries and was highly correlated with total acid producing species. Among children without previous history of caries, Veillonella, but not S. mutans or other acid-producing species, predicted future caries. Bacterial community diversity was reduced in caries as compared to health, as many species appeared to occur at lower levels or be lost as caries advanced, including the Streptococcus mitis group, Neisseria, and Streptococcus sanguinis. This may have

A case of severe soft tissue infection due to Streptococcus tigurinus diagnosed by necropsy in which genomic analysis was useful for clarifying its pathogenicity.

PubMed

Yoshizawa, Hidenori; Motooka, Daisuke; Matsumoto, Yuki; Katada, Ryuichi; Nakamura, Shota; Morii, Eiichi; Iida, Tetsuya; Matsumoto, Hiroshi

2018-05-01

Post-mortem detection of pathogenetic microorganisms in severe infectious death is significantly important for diagnosing the cause of death as well as for public health. However, it is difficult to recognize whether a microorganism detected from post-mortem materials is truly pathogenic or not. We report a case of severe soft tissue infection due to Streptococcus oralis subsp. tigurinus (S. tigurinus), a recently reported species, in which whole-genome analysis was performed to clarify its pathogenicity. A 46-year-old woman had died with symptoms of a severe infectious disease. A post-mortem examination was performed by a medical examiner. The external findings suggested a soft tissue infection; subsequently, pathological specimens sampled by necropsy revealed findings compatible with necrotizing fasciitis. In the post-mortem bacterial test, S. tigurinus was detected from the localized autopsy sample. Whole-genome sequencing was performed to analyze its pathogenicity and detected a strain of S. tigurinus with genetic determinants that were specific and unique to its highly virulent strains as a result of gene annotation. Utilizing various technologies, such as whole-genome sequencing, may be a powerful tool for diagnosing the cause of infectious death accurately and safely. © 2018 Japanese Society of Pathology and John Wiley & Sons Australia, Ltd.

Assessment of bacterial pathogens in fresh rainwater and airborne particulate matter using Real-Time PCR

NASA Astrophysics Data System (ADS)

Kaushik, Rajni; Balasubramanian, Rajasekhar

2012-01-01

Bacterial pathogens in airborne particulate matter (PM) and in rainwater (RW) were detected using a robust and sensitive Real-Time PCR method. Both RW and PM were collected simultaneously in the tropical atmosphere of Singapore, which were then subjected to analysis for the presence of selected bacterial pathogens and potential pathogen of health concern ( Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa and Aeromonas hydrophila). These pathogens were found to be prevalent in both PM and RW samples with E. coli being the most prevalent potential pathogen in both types of samples. The temporal distribution of these pathogens in PM and RW was found to be similar to each other. Using the proposed microbiological technique, the atmospheric deposition (dry and wet deposition) of bacterial pathogens to lakes and reservoirs can be studied in view of growing concerns about the outbreak of waterborne diseases.

Consequences of organ choice in describing bacterial pathogen assemblages in a rodent population.

PubMed

Villette, P; Afonso, E; Couval, G; Levret, A; Galan, M; Tatard, C; Cosson, J F; Giraudoux, P

2017-10-01

High-throughput sequencing technologies now allow for rapid cost-effective surveys of multiple pathogens in many host species including rodents, but it is currently unclear if the organ chosen for screening influences the number and identity of bacteria detected. We used 16S rRNA amplicon sequencing to identify bacterial pathogens in the heart, liver, lungs, kidneys and spleen of 13 water voles (Arvicola terrestris) collected in Franche-Comté, France. We asked if bacterial pathogen assemblages within organs are similar and if all five organs are necessary to detect all of the bacteria present in an individual animal. We identified 24 bacteria representing 17 genera; average bacterial richness for each organ ranged from 1·5 ± 0·4 (mean ± standard error) to 2·5 ± 0·4 bacteria/organ and did not differ significantly between organs. The average bacterial richness when organ assemblages were pooled within animals was 4·7 ± 0·6 bacteria/animal; Operational Taxonomic Unit accumulation analysis indicates that all five organs are required to obtain this. Organ type influences bacterial assemblage composition in a systematic way (PERMANOVA, 999 permutations, pseudo-F 4,51 = 1·37, P = 0·001). Our results demonstrate that the number of organs sampled influences the ability to detect bacterial pathogens, which can inform sampling decisions in public health and wildlife ecology.

Pathogen Identification by Multiplex LightMix Real-Time PCR Assay in Patients with Meningitis and Culture-Negative Cerebrospinal Fluid Specimens

PubMed Central

Wagner, Karoline; Springer, Burkard; Pires, Valeria P.

2017-01-01

ABSTRACT Acute bacterial meningitis is a medical emergency, and delays in initiating effective antimicrobial therapy result in increased morbidity and mortality. Culture-based methods, thus far considered the “gold standard” for identifying bacterial microorganisms, require 24 to 48 h to provide a diagnosis. In addition, antimicrobial therapy is often started prior to clinical sample collection, thereby decreasing the probability of confirming the bacterial pathogen by culture-based methods. To enable a fast and accurate detection of the most important bacterial pathogens causing meningitis, namely, Streptococcus pneumoniae, Haemophilus influenzae, Neisseria meningitidis, Streptococcus agalactiae, and Listeria monocytogenes, we evaluated a commercially available multiplex LightMix real-time PCR (RT-PCR) in 220 cerebrospinal fluid (CSF) specimens. The majority of CSF samples were collected by lumbar puncture, but we also included some CSF samples from patients with symptoms of meningitis from the neurology department that were recovered from shunts. CSF samples were analyzed by multiplex RT-PCR enabling a first diagnosis within a few hours after sample arrival at our institute. In contrast, bacterial identification took between 24 and 48 h by culture. Overall, a high agreement of bacterial identification between culture and multiplex RT-PCR was observed (99%). Moreover, multiplex RT-PCR enabled the detection of pathogens, S. pneumoniae (n = 2), S. agalactiae (n = 1), and N. meningitidis (n = 1), in four culture-negative samples. As a complement to classical bacteriological CSF culture, the LightMix RT-PCR assay proved to be valuable by improving the rapidity and accuracy of the diagnosis of bacterial meningitis. PMID:29237781

Systemic acquired tolerance to virulent bacterial pathogens in tomato.

PubMed

Block, Anna; Schmelz, Eric; O'Donnell, Phillip J; Jones, Jeffrey B; Klee, Harry J

2005-07-01

Recent studies on the interactions between plants and pathogenic microorganisms indicate that the processes of disease symptom development and pathogen growth can be uncoupled. Thus, in many instances, the symptoms associated with disease represent an active host response to the presence of a pathogen. These host responses are frequently mediated by phytohormones. For example, ethylene and salicylic acid (SA) mediate symptom development but do not influence bacterial growth in the interaction between tomato (Lycopersicon esculentum) and virulent Xanthomonas campestris pv vesicatoria (Xcv). It is not apparent why extensive tissue death is integral to a defense response if it does not have the effect of limiting pathogen proliferation. One possible function for this hormone-mediated response is to induce a systemic defense response. We therefore assessed the systemic responses of tomato to Xcv. SA- and ethylene-deficient transgenic lines were used to investigate the roles of these phytohormones in systemic signaling. Virulent and avirulent Xcv did induce a systemic response as evidenced by expression of defense-associated pathogenesis-related genes in an ethylene- and SA-dependent manner. This systemic response reduced cell death but not bacterial growth during subsequent challenge with virulent Xcv. This systemic acquired tolerance (SAT) consists of reduced tissue damage in response to secondary challenge with a virulent pathogen with no effect upon pathogen growth. SAT was associated with a rapid ethylene and pathogenesis-related gene induction upon challenge. SAT was also induced by infection with Pseudomonas syringae pv tomato. These data show that SAT resembles systemic acquired resistance without inhibition of pathogen growth.

PHYLOSCANNER: Inferring Transmission from Within- and Between-Host Pathogen Genetic Diversity

PubMed Central

Hall, Matthew; Ratmann, Oliver; Bonsall, David; Golubchik, Tanya; de Cesare, Mariateresa; Gall, Astrid; Cornelissen, Marion; Fraser, Christophe

2018-01-01

Abstract A central feature of pathogen genomics is that different infectious particles (virions and bacterial cells) within an infected individual may be genetically distinct, with patterns of relatedness among infectious particles being the result of both within-host evolution and transmission from one host to the next. Here, we present a new software tool, phyloscanner, which analyses pathogen diversity from multiple infected hosts. phyloscanner provides unprecedented resolution into the transmission process, allowing inference of the direction of transmission from sequence data alone. Multiply infected individuals are also identified, as they harbor subpopulations of infectious particles that are not connected by within-host evolution, except where recombinant types emerge. Low-level contamination is flagged and removed. We illustrate phyloscanner on both viral and bacterial pathogens, namely HIV-1 sequenced on Illumina and Roche 454 platforms, HCV sequenced with the Oxford Nanopore MinION platform, and Streptococcus pneumoniae with sequences from multiple colonies per individual. phyloscanner is available from https://github.com/BDI-pathogens/phyloscanner. PMID:29186559

Reduced Set of Virulence Genes Allows High Accuracy Prediction of Bacterial Pathogenicity in Humans

PubMed Central

Iraola, Gregorio; Vazquez, Gustavo; Spangenberg, Lucía; Naya, Hugo

2012-01-01

Although there have been great advances in understanding bacterial pathogenesis, there is still a lack of integrative information about what makes a bacterium a human pathogen. The advent of high-throughput sequencing technologies has dramatically increased the amount of completed bacterial genomes, for both known human pathogenic and non-pathogenic strains; this information is now available to investigate genetic features that determine pathogenic phenotypes in bacteria. In this work we determined presence/absence patterns of different virulence-related genes among more than finished bacterial genomes from both human pathogenic and non-pathogenic strains, belonging to different taxonomic groups (i.e: Actinobacteria, Gammaproteobacteria, Firmicutes, etc.). An accuracy of 95% using a cross-fold validation scheme with in-fold feature selection is obtained when classifying human pathogens and non-pathogens. A reduced subset of highly informative genes () is presented and applied to an external validation set. The statistical model was implemented in the BacFier v1.0 software (freely available at ), that displays not only the prediction (pathogen/non-pathogen) and an associated probability for pathogenicity, but also the presence/absence vector for the analyzed genes, so it is possible to decipher the subset of virulence genes responsible for the classification on the analyzed genome. Furthermore, we discuss the biological relevance for bacterial pathogenesis of the core set of genes, corresponding to eight functional categories, all with evident and documented association with the phenotypes of interest. Also, we analyze which functional categories of virulence genes were more distinctive for pathogenicity in each taxonomic group, which seems to be a completely new kind of information and could lead to important evolutionary conclusions. PMID:22916122

Questions about the behaviour of bacterial pathogens in vivo.

PubMed Central

Smith, H

2000-01-01

Bacterial pathogens cause disease in man and animals. They have unique biological properties, which enable them to colonize mucous surfaces, penetrate them, grow in the environment of the host, inhibit or avoid host defences and damage the host. The bacterial products responsible for these five biological requirements are the determinants of pathogenicity (virulence determinants). Current knowledge comes from studies in vitro, but now interest is increasing in how bacteria behave and produce virulence determinants within the infected host. There are three aspects to elucidate: bacterial activities, the host factors that affect them and the metabolic interactions between the two. The first is relatively easy to accomplish and, recently, new methods for doing this have been devised. The second is not easy because of the complexity of the environment in vivo and its ever-changing face. Nevertheless, some information can be gained from the literature and by new methodology. The third aspect is very difficult to study effectively unless some events in vivo can be simulated in vitro. The objectives of the Discussion Meeting were to describe the new methods and to show how they, and conventional studies, are revealing the activities of bacterial pathogens in vivo. This paper sets the scene by raising some questions and suggesting, with examples, how they might be answered. Bacterial growth in vivo is the primary requirement for pathogenicity. Without growth, determinants of the other four requirements are not formed. Results from the new methods are underlining this point. The important questions are as follows. What is the pattern of a developing infection and the growth rates and population sizes of the bacteria at different stages? What nutrients are present in vivo and how do they change as infection progresses and relate to growth rates and population sizes? How are these nutrients metabolized and by what bacterial mechanisms? Which bacterial processes handle

Evaluation of colorimetric loop-mediated isothermal amplification assay for visual detection of Streptococcus agalactiae and Streptococcus iniae in tilapia.

PubMed

Suebsing, R; Kampeera, J; Tookdee, B; Withyachumnarnkul, B; Turner, W; Kiatpathomchai, W

2013-10-01

Streptococcus agalactiae and Strep. iniae are bacterial pathogens that cause streptococcosis in many fish species. An accelerated colorimetric loop-mediated isothermal amplification (LAMP) assay with pre-addition of calcein was established, and the transmission and detection of Strep. agalactiae and Strep. iniae in tilapia under natural aquatic environment were investigated. A positive reaction was observed by a colour change from orange to green through the naked eyes after completion at 63°C for 30 min with 10 times higher sensitivity than that of nested PCR assays and without cross-amplification with other fish bacterial pathogens. All sample types of Nile and red tilapia (broodstock, fertilized egg, fry) were Strep. agalactiae- and Strep. iniae positive by this new method, implying that they could be vertically transmitted. With its application for screening broodstock and fry before stocking and for monitoring fish health in grow-out ponds, the method would become very useful in fish farming industry. The application of colorimetric LAMP with pre-addition of calcein offers simple, rapid and sensitive technique with applicability for small field laboratories. This technique explored the possible vertical transmission mode of Strep. agalactiae and Strep. iniae under natural aquatic environment. It could be such preliminary data provided for the screening broodstock before breeding and/or the specific-pathogen-free production. © 2013 The Society for Applied Microbiology.

Attenuation of Streptococcus suis virulence by the alteration of bacterial surface architecture

PubMed Central

Feng, Youjun; Cao, Min; Shi, Jie; Zhang, Huimin; Hu, Dan; Zhu, Jing; Zhang, Xianyun; Geng, Meiling; Zheng, Feng; Pan, Xiuzhen; Li, Xianfu; Hu, Fuquan; Tang, Jiaqi; Wang, Changjun

2012-01-01

NeuB, a sialic acid synthase catalyzes the last committed step of the de novo biosynthetic pathway of sialic acid, a major element of bacterial surface structure. Here we report a functional NeuB homologue of Streptococcus suis, a zoonotic agent, and systematically address its molecular and immunological role in bacterial virulence. Disruption of neuB led to thinner capsules and more susceptibility to pH, and cps2B inactivation resulted in complete absence of capsular polysaccharides. These two mutants both exhibited increased adhesion and invasion to Hep-2 cells and improved sensibility to phagocytosis. Not only do they retain the capability of inducing the release of host pro-inflammatory cytokines, but also result in the faster secretion of IL-8. Easier cleaning up of the mutant strains in whole blood is consistent with virulence attenuation seen with experimental infections of both mice and SPF-piglets. Therefore we concluded that altered architecture of S. suis surface attenuates its virulence. PMID:23050094

Identification of a two-component Class IIb bacteriocin in Streptococcus pyogenes by recombinase-based in vivo expression technology.

PubMed

Armstrong, Brent D; Herfst, Christine A; Tonial, Nicholas C; Wakabayashi, Adrienne T; Zeppa, Joseph J; McCormick, John K

2016-11-03

Streptococcus pyogenes is a globally prominent bacterial pathogen that exhibits strict tropism for the human host, yet bacterial factors responsible for the ability of S. pyogenes to compete within this limited biological niche are not well understood. Using an engineered recombinase-based in vivo expression technology (RIVET) system, we identified an in vivo-induced promoter region upstream of a predicted Class IIb bacteriocin system in the M18 serotype S. pyogenes strain MGAS8232. This promoter element was not active under in vitro laboratory conditions, but was highly induced within the mouse nasopharynx. Recombinant expression of the predicted mature S. pyogenes bacteriocin peptides (designated SpbM and SpbN) revealed that both peptides were required for antimicrobial activity. Using a gain of function experiment in Lactococcus lactis, we further demonstrated S. pyogenes immunity function is encoded downstream of spbN. These data highlight the importance of bacterial gene regulation within appropriate environments to help understand mechanisms of niche adaptation by bacterial pathogens.

Identification of a two-component Class IIb bacteriocin in Streptococcus pyogenes by recombinase-based in vivo expression technology

PubMed Central

Armstrong, Brent D.; Herfst, Christine A.; Tonial, Nicholas C.; Wakabayashi, Adrienne T.; Zeppa, Joseph J.; McCormick, John K.

2016-01-01

Streptococcus pyogenes is a globally prominent bacterial pathogen that exhibits strict tropism for the human host, yet bacterial factors responsible for the ability of S. pyogenes to compete within this limited biological niche are not well understood. Using an engineered recombinase-based in vivo expression technology (RIVET) system, we identified an in vivo-induced promoter region upstream of a predicted Class IIb bacteriocin system in the M18 serotype S. pyogenes strain MGAS8232. This promoter element was not active under in vitro laboratory conditions, but was highly induced within the mouse nasopharynx. Recombinant expression of the predicted mature S. pyogenes bacteriocin peptides (designated SpbM and SpbN) revealed that both peptides were required for antimicrobial activity. Using a gain of function experiment in Lactococcus lactis, we further demonstrated S. pyogenes immunity function is encoded downstream of spbN. These data highlight the importance of bacterial gene regulation within appropriate environments to help understand mechanisms of niche adaptation by bacterial pathogens. PMID:27808235

Streptococcus agalactiae vaginitis: nonhemolytic variant on the Liofilchem® Chromatic StreptoB.

PubMed

Savini, Vincenzo; Marrollo, Roberta; D'Antonio, Marianna; D'Amario, Claudio; Fazii, Paolo; D'Antonio, Domenico

2013-01-01

Streptococcus agalactiae (group B Streptococcus, GBS) vaginal pathogenicity is not uniformly acknowledged throughout the literature; accordingly, in women, genital itching and burning, along with leukorrhea are commonly and almost exclusively referred to bacterial vaginosis, candidiasis and trichomoniasis. Conversely, GBS virulence for vagina was recognized in the past, as the organism has been observed to potentially cause local inflammation and discharge, as well as lactobacilli rarefaction. We depict here a case where a nonhemolytic (γ-hemolytic) GBS strain was found to be the etiologic agent of vaginal infection. Such uncommon S. agalactiae phenotypes are hard to be recognized and may be therefore responsible for misdiagnosing and underestimation of GBS vaginitis prevalence; here, we had the support of the Liofilchem(®) Chromatic StreptoB medium, that successfully detected such an atypical variant.

Streptococcus agalactiae vaginitis: nonhemolytic variant on the Liofilchem® Chromatic StreptoB

PubMed Central

Savini, Vincenzo; Marrollo, Roberta; D’Antonio, Marianna; D’Amario, Claudio; Fazii, Paolo; D’Antonio, Domenico

2013-01-01

Streptococcus agalactiae (group B Streptococcus, GBS) vaginal pathogenicity is not uniformly acknowledged throughout the literature; accordingly, in women, genital itching and burning, along with leukorrhea are commonly and almost exclusively referred to bacterial vaginosis, candidiasis and trichomoniasis. Conversely, GBS virulence for vagina was recognized in the past, as the organism has been observed to potentially cause local inflammation and discharge, as well as lactobacilli rarefaction. We depict here a case where a nonhemolytic (γ-hemolytic) GBS strain was found to be the etiologic agent of vaginal infection. Such uncommon S. agalactiae phenotypes are hard to be recognized and may be therefore responsible for misdiagnosing and underestimation of GBS vaginitis prevalence; here, we had the support of the Liofilchem® Chromatic StreptoB medium, that successfully detected such an atypical variant. PMID:23923091

Probiotic E. coli Nissle 1917 biofilms on silicone substrates for bacterial interference against pathogen colonization.

PubMed

Chen, Quan; Zhu, Zhiling; Wang, Jun; Lopez, Analette I; Li, Siheng; Kumar, Amit; Yu, Fei; Chen, Haoqing; Cai, Chengzhi; Zhang, Lijuan

2017-03-01

Bacterial interference is an alternative strategy to fight against device-associated bacterial infections. Pursuing this strategy, a non-pathogenic bacterial biofilm is used as a live, protective barrier to fence off pathogen colonization. In this work, biofilms formed by probiotic Escherichia coli strain Nissle 1917 (EcN) are investigated for their potential for long-term bacterial interference against infections associated with silicone-based urinary catheters and indwelling catheters used in the digestive system, such as feeding tubes and voice prostheses. We have shown that EcN can form stable biofilms on silicone substrates, particularly those modified with a biphenyl mannoside derivative. These biofilms greatly reduced the colonization by pathogenic Enterococcus faecalis in Lysogeny broth (LB) for 11days. Bacterial interference is an alternative strategy to fight against device-associated bacterial infections. Pursuing this strategy, we use non-pathogenic bacteria to form a biofilm that serves as a live, protective barrier against pathogen colonization. Herein, we report the first use of preformed probiotic E. coli Nissle 1917 biofilms on the mannoside-presenting silicone substrates to prevent pathogen colonization. The biofilms serve as a live, protective barrier to fence off the pathogens, whereas current antimicrobial/antifouling coatings are subjected to gradual coverage by the biomass from the rapidly growing pathogens in a high-nutrient environment. It should be noted that E. coli Nissle 1917 is commercially available and has been used in many clinical trials. We also demonstrated that this probiotic strain performed significantly better than the non-commercial, genetically modified E. coli strain that we previously reported. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Autophagic clearance of bacterial pathogens: molecular recognition of intracellular microorganisms.

PubMed

Pareja, Maria Eugenia Mansilla; Colombo, Maria I

2013-01-01

Autophagy is involved in several physiological and pathological processes. One of the key roles of the autophagic pathway is to participate in the first line of defense against the invasion of pathogens, as part of the innate immune response. Targeting of intracellular bacteria by the autophagic machinery, either in the cytoplasm or within vacuolar compartments, helps to control bacterial proliferation in the host cell, controlling also the spreading of the infection. In this review we will describe the means used by diverse bacterial pathogens to survive intracellularly and how they are recognized by the autophagic molecular machinery, as well as the mechanisms used to avoid autophagic clearance.

Udder infections with Staphylococcus aureus, Streptococcus dysgalactiae, and Streptococcus uberis at calving in dairy herds with suboptimal udder health.

PubMed

Lundberg, Å; Nyman, A-K; Aspán, A; Börjesson, S; Unnerstad, H Ericsson; Waller, K Persson

2016-03-01

Udder infections with Staphylococcus aureus, Streptococcus dysgalactiae, and Streptococcus uberis are common causes of bovine mastitis. To study these pathogens in early lactation, a 12-mo longitudinal, observational study was carried out in 13 herds with suboptimal udder health. The aims of the study were to investigate the occurrence of these pathogens and to identify if presence of the 3 pathogens, and of genotypes within the pathogens, differed with respect to herd, season, and parity. Quarter milk samples, collected at calving and 4 d in milk (DIM), were cultured for the 3 pathogens. Genotyping of staphylococcal and streptococcal isolates was performed using spa typing and pulsed-field gel electrophoresis, respectively. For each of the 3 pathogens, cows with an udder infection at calving or 4 DIM were allocated to 1 of 4 infection types: cleared (pathogen present only at calving), persistent (pathogen present in the same quarter at calving and 4 DIM), new (pathogen present only at 4 DIM), or cleared/new (pathogen present in 1 quarter at calving and in another quarter at 4 DIM). Associations between season or parity and overall occurrence of pathogens or infection types were determined using univariable mixed-effect logistic-regression models and the Fisher's exact test, respectively. The most commonly occurring pathogen was Staph. aureus, followed by Strep. dysgalactiae and Strep. uberis. Persistent infections were the most common infection type among Staph. aureus-infected cows, whereas cleared infections were the most common among Strep. dysgalactiae- and Strep. uberis-positive cows. The proportion of cows with persistent Staph. aureus infections and the proportion of cows having a Strep. uberis infection at calving or 4 DIM were higher in the multiparous cows than in primiparous cows. Infections with Strep. dysgalactiae were less common during the early housing season than during the late housing or pasture seasons, whereas persistent Strep. uberis

Competition between yogurt probiotics and periodontal pathogens in vitro.

PubMed

Zhu, Yunwo; Xiao, Liying; Shen, Da; Hao, Yuqing

2010-09-01

To investigate the competition between probiotics in bio-yogurt and periodontal pathogens in vitro. The antimicrobial activity of bio-yogurt was studied by agar diffusion assays, using eight species of putative periodontal pathogens and a 'protective bacteria' as indicator strains. Four probiotic bacterial species (Lactobacillus bulgaricus, Streptococcus thermophilus, Lactobacillus acidophilus, and Bifidobacterium) were isolated from yogurt and used to rate the competitive exclusion between probiotics and periodontal pathogens. Fresh yogurt inhibited all the periodontal pathogens included in this work, showing inhibition zones ranging from 9.3 (standard deviation 0.6) mm to 17.3 (standard deviation 1.7) mm, whereas heat-treated yogurt showed lower antimicrobial activity. In addition, neither fresh yogurt nor heat-treated yogurt inhibited the 'protective bacteria', Streptococcus sanguinis. The competition between yogurt probiotics and periodontal pathogens depended on the sequence of inoculation. When probiotics were inoculated first, Bifidobacterium inhibited Porphyromonas gingivalis, Fusobacterium nucleatum, Aggregatibacter actinomycetemcomitans, Porphyromonas circumdentaria, and Prevotella nigrescens; L. acidophilus inhibited P. gingivalis, A. actinomycetemcomitans, P. circumdentaria, P. nigrescens, and Peptostreptococcus anaerobius; L. bulgaricus inhibited P. gingivalis, A. actinomycetemcomitans, and P. nigrescens; and S. thermophilus inhibited P. gingivalis, F. nucleatum, and P. nigrescens. However, their antimicrobial properties were reduced when both species (probiotics and periodontal pathogens) were inoculated simultaneously. When periodontal pathogens were inoculated first, Prevotella intermedia inhibited Bifidobacterium and S. thermophilus. The results demonstrated that bio-yogurt and the probiotics that it contains are capable of inhibiting specific periodontal pathogens but have no effect on the periodontal protective bacteria.

Non-pathogenic microflora of a spring water with regenerative properties.

PubMed

Nicoletti, Giovanni; Corbella, Marta; Jaber, Omar; Marone, Piero; Scevola, Daniele; Faga, Angela

2015-11-01

The Comano spring water (Comano, Italy) has been demonstrated to improve skin regeneration, not only by increasing keratinocyte proliferation and migration, but also by modulating the regenerated collagen and elastic fibers in the dermis. However, such biological properties may not be entirely explained by its mineral composition only. As the non-pathogenic bacterial populations have demonstrated an active role in different biological processes, the potential presence of non-pathogenic bacterial species within the Comano spring water was investigated in order to identify any possible correlation between these bacterial populations and the demonstrated biological properties of this water. The water was collected at the spring using an aseptic procedure and multiple cultures were carried out. A total of 9 different strains were isolated, which were Aeromonas hydrophila , Brevundimonas vesicularis , Chromobacterium violaceum , Citrobacter youngae , Empedobacter brevis , Pantoea agglomerans , Pseudomonas putida , Pseudomonas stutzeri and Streptococcus mitis . All the isolated bacterial strains, although showing a rare potential virulence, demonstrated peculiar and favorable metabolic attitudes in controlling environmental pollution. The therapeutical effects of certain spring waters are currently being proven as correlated not only to their peculiar mineral composition, but also to the complex activity of their resident non-pathogenic bacterial populations. Although the present study provided only preliminary data, some of the non-pathogenic bacterial populations that were identified in the Comano spring water are likely to produce molecular mediators with a role in the wound healing process that, thus far, remain unknown. Numerous other unknown bacterial species, comprehensively termed DNA-rich 'dark matter', are likely to contribute to the Comano water regenerative properties as well. Therefore, the non-pathogenic bacterial populations of the Comano spring water are

The association between bedding material and the bacterial counts of Staphylococcus aureus, Streptococcus uberis and coliform bacteria on teat skin and in teat canals in lactating dairy cattle.

PubMed

Paduch, Jan-Hendrik; Mohr, Elmar; Krömker, Volker

2013-05-01

Several mastitis-causing pathogens are able to colonize the bovine teat canal. The objective of this study was to investigate the association between the treatment of sawdust bedding with a commercial alkaline conditioner and the bacterial counts on teat skin and in the teat canal. The study used a crossover design. Ten lactating Holstein cows that were free of udder infections and mastitis were included in the study. The animals were bedded on either untreated sawdust or sawdust that had been treated with a hydrated lime-based conditioner. Once a day, fresh bedding material was added. After 3 weeks, the bedding material was removed from the cubicles, fresh bedding material was provided, and the cows were rotated between the two bedding material groups. Teat skin and teat canals were sampled using the wet and dry swab technique after weeks 1, 2, 3, 4, 5 and 6. Staphylococcus aureus, Streptococcus uberis, Escherichia coli and other coliform bacteria were detected in the resulting agar plate cultures. The treatment of the bedding material was associated with the teat skin bacterial counts of Str. uberis, Esch. coli and other coliform bacteria. An association was also found between the bedding material and the teat canal bacterial counts of coliform bacteria other than Esch. coli. For Staph. aureus, no associations with the bedding material were found. In general, the addition of a hydrated lime-based conditioner to sawdust reduces the population sizes of environmental pathogens on teat skin and in teat canals.

Two zinc-binding domains in the transporter AdcA from Streptococcus pyogenes facilitate high-affinity binding and fast transport of zinc.

PubMed

Cao, Kun; Li, Nan; Wang, Hongcui; Cao, Xin; He, Jiaojiao; Zhang, Bing; He, Qing-Yu; Zhang, Gong; Sun, Xuesong

2018-04-20

Zinc is an essential metal in bacteria. One important bacterial zinc transporter is AdcA, and most bacteria possess AdcA homologs that are single-domain small proteins due to better efficiency of protein biogenesis. However, a double-domain AdcA with two zinc-binding sites is significantly overrepresented in Streptococcus species, many of which are major human pathogens. Using molecular simulation and experimental validations of AdcA from Streptococcus pyogenes , we found here that the two AdcA domains sequentially stabilize the structure upon zinc binding, indicating an organization required for both increased zinc affinity and transfer speed. This structural organization appears to endow Streptococcus species with distinct advantages in zinc-depleted environments, which would not be achieved by each single AdcA domain alone. This enhanced zinc transport mechanism sheds light on the significance of the evolution of the AdcA domain fusion, provides new insights into double-domain transporter proteins with two binding sites for the same ion, and indicates a potential target of antimicrobial drugs against pathogenic Streptococcus species. © 2018 by The American Society for Biochemistry and Molecular Biology, Inc.

Serotype distribution of Streptococcus mutans a pathogen of dental caries in cardiovascular specimens from Japanese patients.

PubMed

Nakano, Kazuhiko; Nemoto, Hirotoshi; Nomura, Ryota; Homma, Hiromi; Yoshioka, Hideo; Shudo, Yasuhiro; Hata, Hiroki; Toda, Koichi; Taniguchi, Kazuhiro; Amano, Atsuo; Ooshima, Takashi

2007-04-01

The involvement of oral bacteria in the pathogenesis of cardiovascular disease has been studied, with Streptococcus mutans, a pathogen of dental caries, detected in cardiovascular lesions at a high frequency. However, no information is available regarding the properties of S. mutans detected in those lesions. Heart valve specimens were collected from 52 patients and atheromatous plaque specimens from 50 patients, all of whom underwent cardiovascular operations, and dental plaque specimens were taken from 41 of those subjects prior to surgery. Furthermore, saliva samples were taken from 73 sets of healthy mothers (n=73) and their healthy children (n=78). Bacterial DNA was extracted from all specimens, then analysed by PCR with S. mutans-specific and serotype-specific primer sets. The detection rates of S. mutans in the heart valve and atheromatous plaque specimens were 63 and 64 %, respectively. Non-c serotypes were identified with a significantly higher frequency in both cardiovascular and dental plaque samples from the subjects who underwent surgery as compared to serotype c, which was detected in 70-75 % of the samples from the healthy subjects. The serotype distribution in cardiovascular patients was significantly different from that in healthy subjects, suggesting that S. mutans serotype may be related to cardiovascular disease.

A hypothetical model of host-pathogen interaction of Streptococcus suis in the gastro-intestinal tract

PubMed Central

Ferrando, Maria Laura; Schultsz, Constance

2016-01-01

ABSTRACT Streptococcus suis (SS) is a zoonotic pathogen that can cause systemic infection in pigs and humans. The ingestion of contaminated pig meat is a well-established risk factor for zoonotic S. suis disease. In our studies, we provide experimental evidence that S. suis is capable to translocate across the host gastro-intestinal tract (GIT) using in vivo and in vitro models. Hence, S. suis should be considered an emerging foodborne pathogen. In this addendum, we give an overview of the complex interactions between S. suis and host-intestinal mucosa which depends on the host origin, the serotype and genotype of S. suis, as well as the presence and expression of virulence factors involved in host-pathogen interaction. Finally, we propose a hypothetical model of S. suis interaction with the host-GIT taking in account differences in conditions between the porcine and human host. PMID:26900998

Production of recombinant streptokinase from Streptococcus pyogenes isolate and its potential for thrombolytic therapy.

PubMed

Assiri, Abdullah S; El-Gamal, Basiouny A; Hafez, Elsayed E; Haidara, Mohamed A

2014-12-01

To produce an effective recombinant streptokinase (rSK) from pathogenic Streptococcus pyogenes isolate in yeast, and evaluate its potential for thrombolytic therapy. This study was conducted from November 2012 to December 2013 at King Khalid University, Abha, Kingdom of Saudi Arabia (KSA). Throat swabs collected from 45 pharyngitis patients in Asser Central Hospital, Abha, KSA were used to isolate Streptococcus pyogenes. The bacterial DNA was used for amplification of the streptokinase gene (1200 bp). The gene was cloned and in vitro transcribed in an eukaryotic expression vector that was transformed into yeast Pichia pastoris SMD1168, and the rSK protein was purified and tested for its thrombolytic activity. The Streptococcus pyogenes strain was isolated and its DNA nucleotide sequence revealed similarity to other Streptococcus pyogenes in the Gene bank. Sequencing of the amplified gene based on DNA nucleotide sequence revealed a SK gene closely related to other SK genes in the Gene bank. However, based on deduced amino acids sequence, the gene formed a separate cluster different from clusters formed by other examined genes, suggesting a new bacterial isolate and accordingly a new gene. The purified protein showed 82% clot lysis compared to a commercial SK (81%) at an enzyme concentration of 2000 U/ml. The present yeast rSK showed similar thrombolytic activity in vitro as that of a commercial SK, suggesting its potential for thrombolytic therapy and large scale production. 

The role and regulation of catalase in respiratory tract opportunistic bacterial pathogens.

PubMed

Eason, Mia M; Fan, Xin

2014-09-01

Respiratory tract bacterial pathogens are the etiologic agents of a variety of illnesses. The ability of these bacteria to cause disease is imparted through survival within the host and avoidance of pathogen clearance by the immune system. Respiratory tract pathogens are continually bombarded by reactive oxygen species (ROS), which may be produced by competing bacteria, normal metabolic function, or host immunological responses. In order to survive and proliferate, bacteria have adapted defense mechanisms to circumvent the effects of ROS. Bacteria employ the use of anti-oxidant enzymes, catalases and catalase-peroxidases, to relieve the effects of the oxidative stressors to which they are continually exposed. The decomposition of ROS has been shown to provide favorable conditions in which respiratory tract opportunistic bacterial pathogens such as Haemophilus influenzae, Mycobacterium tuberculosis, Legionella pneumophila, and Neisseria meningitidis are able to withstand exposure to highly reactive molecules and yet survive. Bacteria possessing mutations in the catalase gene have a decreased survival rate, yet may be able to compensate for the lack of catalatic activity if peroxidatic activity is present. An incomplete knowledge of the mechanisms by which catalase and catalase-peroxidases are regulated still persists, however, in some bacterial species, a regulatory factor known as OxyR has been shown to either up-regulate or down-regulate catalase gene expression. Yet, more research is still needed to increase the knowledge base in relation to this enzyme class. As with this review, we focus on major respiratory tract opportunistic bacterial pathogens in order to elucidate the function and regulation of catalases. The importance of the research could lead to the development of novel treatments against respiratory bacterial infections. Copyright © 2014 Elsevier Ltd. All rights reserved.

Antibiotic Susceptibility Patterns of Bacterial Isolates from Pus Samples in a Tertiary Care Hospital of Punjab, India

PubMed Central

Trojan, Rugira; Razdan, Lovely

2016-01-01

We determined the prevalence and antibiotic susceptibilities patterns of bacterial isolates from pus samples collected from patients in a tertiary care hospital of Punjab, India. E. coli was the most prevalent pathogen (51.2%) followed by Staphylococcus aureus (21%), Klebsiella pneumoniae (11.6%), Pseudomonas aeruginosa (5.8%), Citrobacter spp. (3.5%), Acinetobacter baumannii (2.3%), Proteus mirabilis (2.3%), and Streptococcus spp. (2.3%). E. coli, K. pneumoniae, A. baumannii, and Citrobacter isolates were resistant to multiple antibiotics including higher generation cephalosporins. S. aureus and Streptococcus isolates were sensitive to cloxacillin and vancomycin. However, P. aeruginosa, P. mirabilis, and Streptococcus isolates were found to be less resistant to the spectrum of antibiotics tested. Overall, our findings indicate the prevalence of resistance to different classes of antibiotics in bacterial isolates from pus infections and hence highlight the need for effective surveillance, regulator reporting, and antibiogram-guided antibiotic prescription. PMID:27872643

Antibiotic Susceptibility Patterns of Bacterial Isolates from Pus Samples in a Tertiary Care Hospital of Punjab, India.

PubMed

Trojan, Rugira; Razdan, Lovely; Singh, Nasib

2016-01-01

We determined the prevalence and antibiotic susceptibilities patterns of bacterial isolates from pus samples collected from patients in a tertiary care hospital of Punjab, India. E. coli was the most prevalent pathogen (51.2%) followed by Staphylococcus aureus (21%), Klebsiella pneumoniae (11.6%), Pseudomonas aeruginosa (5.8%), Citrobacte r spp. (3.5%), Acinetobacter baumannii (2.3%), Proteus mirabilis (2.3%), and Streptococcus spp. (2.3%). E. coli , K. pneumoniae , A. baumannii , and Citrobacter isolates were resistant to multiple antibiotics including higher generation cephalosporins. S. aureus and Streptococcus isolates were sensitive to cloxacillin and vancomycin. However, P. aeruginosa , P. mirabilis , and Streptococcus isolates were found to be less resistant to the spectrum of antibiotics tested. Overall, our findings indicate the prevalence of resistance to different classes of antibiotics in bacterial isolates from pus infections and hence highlight the need for effective surveillance, regulator reporting, and antibiogram-guided antibiotic prescription.

Group A Streptococcus tissue invasion by CD44-mediated cell signalling

NASA Astrophysics Data System (ADS)

Cywes, Colette; Wessels, Michael R.

2001-12-01

Streptococcus pyogenes (also known as group A Streptococcus, GAS), the agent of streptococcal sore throat and invasive soft-tissue infections, attaches to human pharyngeal or skin epithelial cells through specific recognition of its hyaluronic acid capsular polysaccharide by the hyaluronic-acid-binding protein CD44 (refs 1, 2). Because ligation of CD44 by hyaluronic acid can induce epithelial cell movement on extracellular matrix, we investigated whether molecular mimicry by the GAS hyaluronic acid capsule might induce similar cellular responses. Here we show that CD44-dependent GAS binding to polarized monolayers of human keratinocytes induced marked cytoskeletal rearrangements manifested by membrane ruffling and disruption of intercellular junctions. Transduction of the signal induced by GAS binding to CD44 on the keratinocyte surface involved Rac1 and the cytoskeleton linker protein ezrin, as well as tyrosine phosphorylation of cellular proteins. Studies of bacterial translocation in two models of human skin indicated that cell signalling triggered by interaction of the GAS capsule with CD44 opened intercellular junctions and promoted tissue penetration by GAS through a paracellular route. These results support a model of host cytoskeleton manipulation and tissue invasion by an extracellular bacterial pathogen.

A Highly Arginolytic Streptococcus Species That Potently Antagonizes Streptococcus mutans

PubMed Central

Huang, Xuelian; Palmer, Sara R.; Ahn, Sang-Joon; Richards, Vincent P.; Williams, Matthew L.; Nascimento, Marcelle M.

2016-01-01

The ability of certain oral biofilm bacteria to moderate pH through arginine metabolism by the arginine deiminase system (ADS) is a deterrent to the development of dental caries. Here, we characterize a novel Streptococcus strain, designated strain A12, isolated from supragingival dental plaque of a caries-free individual. A12 not only expressed the ADS pathway at high levels under a variety of conditions but also effectively inhibited growth and two intercellular signaling pathways of the dental caries pathogen Streptococcus mutans. A12 produced copious amounts of H2O2 via the pyruvate oxidase enzyme that were sufficient to arrest the growth of S. mutans. A12 also produced a protease similar to challisin (Sgc) of Streptococcus gordonii that was able to block the competence-stimulating peptide (CSP)–ComDE signaling system, which is essential for bacteriocin production by S. mutans. Wild-type A12, but not an sgc mutant derivative, could protect the sensitive indicator strain Streptococcus sanguinis SK150 from killing by the bacteriocins of S. mutans. A12, but not S. gordonii, could also block the XIP (comX-inducing peptide) signaling pathway, which is the proximal regulator of genetic competence in S. mutans, but Sgc was not required for this activity. The complete genome sequence of A12 was determined, and phylogenomic analyses compared A12 to streptococcal reference genomes. A12 was most similar to Streptococcus australis and Streptococcus parasanguinis but sufficiently different that it may represent a new species. A12-like organisms may play crucial roles in the promotion of stable, health-associated oral biofilm communities by moderating plaque pH and interfering with the growth and virulence of caries pathogens. PMID:26826230

A Highly Arginolytic Streptococcus Species That Potently Antagonizes Streptococcus mutans.

PubMed

Huang, Xuelian; Palmer, Sara R; Ahn, Sang-Joon; Richards, Vincent P; Williams, Matthew L; Nascimento, Marcelle M; Burne, Robert A

2016-01-29

The ability of certain oral biofilm bacteria to moderate pH through arginine metabolism by the arginine deiminase system (ADS) is a deterrent to the development of dental caries. Here, we characterize a novel Streptococcus strain, designated strain A12, isolated from supragingival dental plaque of a caries-free individual. A12 not only expressed the ADS pathway at high levels under a variety of conditions but also effectively inhibited growth and two intercellular signaling pathways of the dental caries pathogen Streptococcus mutans. A12 produced copious amounts of H2O2 via the pyruvate oxidase enzyme that were sufficient to arrest the growth of S. mutans. A12 also produced a protease similar to challisin (Sgc) of Streptococcus gordonii that was able to block the competence-stimulating peptide (CSP)-ComDE signaling system, which is essential for bacteriocin production by S. mutans. Wild-type A12, but not an sgc mutant derivative, could protect the sensitive indicator strain Streptococcus sanguinis SK150 from killing by the bacteriocins of S. mutans. A12, but not S. gordonii, could also block the XIP (comX-inducing peptide) signaling pathway, which is the proximal regulator of genetic competence in S. mutans, but Sgc was not required for this activity. The complete genome sequence of A12 was determined, and phylogenomic analyses compared A12 to streptococcal reference genomes. A12 was most similar to Streptococcus australis and Streptococcus parasanguinis but sufficiently different that it may represent a new species. A12-like organisms may play crucial roles in the promotion of stable, health-associated oral biofilm communities by moderating plaque pH and interfering with the growth and virulence of caries pathogens. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

Lack of Toll-like receptor 2 results in higher mortality of bacterial meningitis by impaired host resistance.

PubMed

Böhland, Martin; Kress, Eugenia; Stope, Matthias B; Pufe, Thomas; Tauber, Simone C; Brandenburg, Lars-Ove

2016-10-15

Bacterial meningitis is - despite therapeutical progress during the last decades - still characterized by high mortality and severe permanent neurogical sequelae. The brain is protected from penetrating pathogens by both the blood-brain barrier and the innate immune system. Invading pathogens are recognized by so-called pattern recognition receptors including the Toll-like receptors (TLR) which are expressed by glial immune cells in the central nervous system. Among these, TLR2 is responsible for the detection of Gram-positive bacteria such as the meningitis-causing pathogen Streptococcus pneumoniae. Here, we used TLR2-deficient mice to investigate the effects on mortality, bacterial growth and inflammation in a mouse model of pneumococcal meningitis. Our results revealed a significantly increased mortality rate and higher bacterial burden in TLR2-deficient mice with pneumococcal meningitis. Furthermore, infected TLR2-deficient mice suffered from a significantly increased pro-inflammatory cytokine tumor necrosis factor-α (TNF-α) and Chemokine (C-C motif) ligand 2 (CCL2) or CCL3 chemokine expression and decreased expression of anti-inflammatory cytokines and antimicrobial peptides. In contrast, glial cell activation assessed by glial cell marker expression was comparable to wildtype mice. Taken together, the results suggest that TLR2 is essential for an efficient immune response against Streptococcus pneumoniae meningitis since lack of the receptor led to a worse outcome by higher mortality due to increased bacterial burden, weakened innate immune response and reduced expression of antimicrobial peptides. Copyright © 2016 Elsevier B.V. All rights reserved.

Genomic comparison between pathogenic Streptococcus agalactiae isolated from Nile tilapia in Thailand and fish-derived ST7 strains.

PubMed

Kayansamruaj, Pattanapon; Pirarat, Nopadon; Kondo, Hidehiro; Hirono, Ikuo; Rodkhum, Channarong

2015-12-01

Streptococcus agalactiae, or Group B streptococcus (GBS), is a highly virulent pathogen in aquatic animals, causing huge mortalities worldwide. In Thailand, the serotype Ia, β-hemolytic GBS, belonging to sequence type (ST) 7 of clonal complex (CC) 7, was found to be the major cause of streptococcosis outbreaks in fish farms. In this study, we performed an in silico genomic comparison, aiming to investigate the phylogenetic relationship between the pathogenic fish strains of Thai ST7 and other ST7 from different hosts and geographical origins. In general, the genomes of Thai ST7 strains are closely related to other fish ST7s, as the core genome is shared by 92-95% of any individual fish ST7 genome. Among the fish ST7 genomes, we observed only small dissimilarities, based on the analysis of clustered regularly interspaced short palindromic repeats (CRISPRs), surface protein markers, insertions sequence (IS) elements and putative virulence genes. The phylogenetic tree based on single nucleotide polymorphisms (SNPs) of the core genome sequences clearly categorized the ST7 strains according to their geographical and host origins, with the human ST7 being genetically distant from other fish ST7 strains. A pan-genome analysis of ST7 strains detected a 48-kb gene island specifically in the Thai ST7 isolates. The orientations and predicted amino acid sequences of the genes in the island closely matched those of Tn5252, a streptococcal conjugative transposon, in GBS 2603V/R serotype V, Streptococcus pneumoniae and Streptococcus suis. Thus, it was presumed that Thai ST7 acquired this Tn5252 homologue from related streptococci. The close phylogenetic relationship between the fish ST7 strains suggests that these strains were derived from a common ancestor and have diverged in different geographical regions and in different hosts. Copyright © 2015 Elsevier B.V. All rights reserved.

Novel bacterial ADP-ribosylating toxins: structure and function

PubMed Central

Simon, Nathan C.; Aktories, Klaus; Barbieri, Joseph T.

2018-01-01

Preface Bacterial ADP-ribosyltransferase toxins (bARTTs) transfer ADP-ribose to eukaryotic proteins to promote bacterial pathogenesis. In this review we use prototype bARTTs, such as diphtheria and pertussis toxins, as references for the characterization of several new bARTTs from human, insect, and plant pathogens, which were identified recently through bioinformatic analyses. Several of these toxins, including Cholix toxin from Vibrio cholerae, SpyA from Streptococcus pyogenes, HopU1 from Pseudomonas syringae, and the Tcc toxins from Photorhabdus luminescens, ADP-ribosylate novel substrates and possess unique organizations, which distinguish them from the reference toxins. The characterization of these toxins extends our appreciation for the variety of structure-function properties possessed by bARTTs and their roles in bacterial pathogenesis. PMID:25023120

Chromosomal islands of Streptococcus pyogenes and related streptococci: molecular switches for survival and virulence

PubMed Central

Nguyen, Scott V.; McShan, William M.

2014-01-01

Streptococcus pyogenes is a significant pathogen of humans, annually causing over 700,000,000 infections and 500,000 deaths. Virulence in S. pyogenes is closely linked to mobile genetic elements like phages and chromosomal islands (CI). S. pyogenes phage-like chromosomal islands (SpyCI) confer a complex mutator phenotype on their host. SpyCI integrate into the 5′ end of DNA mismatch repair (MMR) gene mutL, which also disrupts downstream operon genes lmrP, ruvA, and tag. During early logarithmic growth, SpyCI excise from the bacterial chromosome and replicate as episomes, relieving the mutator phenotype. As growth slows and the cells enter stationary phase, SpyCI reintegrate into the chromosome, again silencing the MMR operon. This system creates a unique growth-dependent and reversible mutator phenotype. Additional CI using the identical attachment site in mutL have been identified in related species, including Streptococcus dysgalactiae subsp. equisimilis, Streptococcus anginosus, Streptococcus intermedius, Streptococcus parauberis, and Streptococcus canis. These CI have small genomes, which range from 13 to 20 kB, conserved integrase and DNA replication genes, and no identifiable genes encoding capsid proteins. SpyCI may employ a helper phage for packaging and dissemination in a fashion similar to the Staphylococcus aureus pathogenicity islands (SaPI). Outside of the core replication and integration genes, SpyCI and related CI show considerable diversity with the presence of many indels that may contribute to the host cell phenotype or fitness. SpyCI are a subset of a larger family of streptococcal CI who potentially regulate the expression of other host genes. The biological and phylogenetic analysis of streptococcal chromosomal islands provides important clues as to how these chromosomal islands help S. pyogenes and other streptococcal species persist in human populations in spite of antibiotic therapy and immune challenges. PMID:25161960

Chromosomal islands of Streptococcus pyogenes and related streptococci: molecular switches for survival and virulence.

PubMed

Nguyen, Scott V; McShan, William M

2014-01-01

Streptococcus pyogenes is a significant pathogen of humans, annually causing over 700,000,000 infections and 500,000 deaths. Virulence in S. pyogenes is closely linked to mobile genetic elements like phages and chromosomal islands (CI). S. pyogenes phage-like chromosomal islands (SpyCI) confer a complex mutator phenotype on their host. SpyCI integrate into the 5' end of DNA mismatch repair (MMR) gene mutL, which also disrupts downstream operon genes lmrP, ruvA, and tag. During early logarithmic growth, SpyCI excise from the bacterial chromosome and replicate as episomes, relieving the mutator phenotype. As growth slows and the cells enter stationary phase, SpyCI reintegrate into the chromosome, again silencing the MMR operon. This system creates a unique growth-dependent and reversible mutator phenotype. Additional CI using the identical attachment site in mutL have been identified in related species, including Streptococcus dysgalactiae subsp. equisimilis, Streptococcus anginosus, Streptococcus intermedius, Streptococcus parauberis, and Streptococcus canis. These CI have small genomes, which range from 13 to 20 kB, conserved integrase and DNA replication genes, and no identifiable genes encoding capsid proteins. SpyCI may employ a helper phage for packaging and dissemination in a fashion similar to the Staphylococcus aureus pathogenicity islands (SaPI). Outside of the core replication and integration genes, SpyCI and related CI show considerable diversity with the presence of many indels that may contribute to the host cell phenotype or fitness. SpyCI are a subset of a larger family of streptococcal CI who potentially regulate the expression of other host genes. The biological and phylogenetic analysis of streptococcal chromosomal islands provides important clues as to how these chromosomal islands help S. pyogenes and other streptococcal species persist in human populations in spite of antibiotic therapy and immune challenges.

Development of a multiplex PCR assay for rapid and simultaneous detection of four genera of fish pathogenic bacteria.

PubMed

Zhang, D F; Zhang, Q Q; Li, A H

2014-11-01

Species of genus Aeromonas, Vibrio, Edwardsiella and Streptococcus are the most common fish pathogenic bacteria that cause economically devastating losses in aquaculture. A multiplex polymerase chain reaction (mPCR) was developed for the simultaneous detection and differentiation of the four genera of fish pathogenic bacteria. Through the use of genus-specific primers instead of species-specific ones, the current mPCR covered much more target bacterial species compared with previously reported species-specific mPCR methods. The specificity of the four putative genus-specific primers was validated experimentally while used exclusively (uniplex PCR) or combined (mPCR) against bacterial genomic DNA templates of the target bacteria and nontarget bacteria. The PCR amplicons for the following genera were obtained as expected: Aeromonas (875 bp), Vibrio (524 bp), Edwardsiella (302 bp) and Streptococcus (197 bp), and the fragments could be separated clearly on the agarose gel electrophoresis. The mPCR did not produce nonspecific amplification products when used to amplify 21 nontarget species of bacteria. The mPCR detection limits for each target bacterial genera were 50 colony-forming units (CFU) in pure culture and 100 CFU in fish tissue samples. In conclusion, the mPCR assay was proven to be a powerful alternative to the conventional culture-based method, given its rapid, specific, sensitive and reliable detection of target pathogens. The fish pathogenic bacteria of genus Aeromonas, Vibrio, Edwardsiella and Streptococcus frequently cause severe outbreaks of diseases in cultured fish, and the genus-specific multiplex PCR assay developed in this study can detect the bacteria of the four genera when present in the samples either alone or mixed. The mPCR assay is expected to identify the causative agents more efficiently than uniplex PCR or species-specific multiplex PCR for clinical diagnosis, resulting in the earlier implementation of control measures. This m

Nasopharyngeal bacterial burden and antibiotics: Influence on inflammatory markers and disease severity in infants with respiratory syncytial virus bronchiolitis.

PubMed

Suárez-Arrabal, M Carmen; Mella, Cesar; Lopez, Santiago M; Brown, Nicole V; Hall, Mark W; Hammond, Sue; Shiels, William; Groner, Judith; Marcon, Mario; Ramilo, Octavio; Mejias, Asuncion

2015-10-01

Animal studies suggest that RSV increases nasopharyngeal (NP) bacterial colonization facilitating bacterial infections. We investigated the influence of antibiotic treatment and colonization with potentially pathogenic bacteria on inflammatory markers and disease severity in RSV-infected in infants. Healthy young infants hospitalized with RSV bronchiolitis (n = 136) and age-matched healthy controls (n = 23) were enrolled and NP samples cultured for potentially pathogenic bacteria including: Gram-positive bacteria (GPB): Staphylococcus aureus, Streptococcus pneumoniae, β-hemolytic Streptococcus; and Gram-negative bacteria (GNB): Moraxella catarrhalis and Haemophilus influenzae. Clinical parameters and plasma IL-8, IL-6 and TNF-α concentrations were compared according to the bacterial class and antibiotic treatment. Antibiotic treatment decreased by 10-fold NP bacterial recovery. Eighty-one percent of RSV infants who did not receive antibiotics before sample collection were colonized with pathogenic bacteria. Overall, GNB were identified in 21% of patients versus 4% of controls who were mostly colonized with GPB. Additionally, in RSV patients NP white blood cell counts (p = 0.026), and blood neutrophils (p = 0.02) were higher in those colonized with potentially pathogenic bacteria versus respiratory flora. RSV patients colonized with GNB had higher plasma IL-8 (p = 0.01) and IL-6 (p < 0.01) concentrations than controls, and required longer duration of oxygen (p = 0.049). Infants with RSV bronchiolitis colonized with potentially pathogenic bacteria had increased numbers of mucosal and systemic inflammatory cells. Specifically, colonization with GNB was associated with higher concentrations of proinflammatory cytokines and a trend towards increased disease severity. Copyright © 2015 The British Infection Association. Published by Elsevier Ltd. All rights reserved.

Kinetics of Coinfection with Influenza A Virus and Streptococcus pneumoniae

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smith, Amber M.; Adler, Frederick R.; Ribeiro, Ruy M.

Secondary bacterial infections are a leading cause of illness and death during epidemic and pandemic influenza. Experimental studies suggest a lethal synergism between influenza and certain bacteria, particularly Streptococcus pneumoniae, but the precise processes involved are unclear. In this paper, to address the mechanisms and determine the influences of pathogen dose and strain on disease, we infected groups of mice with either the H1N1 subtype influenza A virus A/Puerto Rico/8/34 (PR8) or a version expressing the 1918 PB1-F2 protein (PR8-PB1-F2(1918)), followed seven days later with one of two S. pneumoniae strains, type 2 D39 or type 3 A66.1. We determinedmore » that, following bacterial infection, viral titers initially rebound and then decline slowly. Bacterial titers rapidly rise to high levels and remain elevated. We used a kinetic model to explore the coupled interactions and study the dominant controlling mechanisms. We hypothesize that viral titers rebound in the presence of bacteria due to enhanced viral release from infected cells, and that bacterial titers increase due to alveolar macrophage impairment. Dynamics are affected by initial bacterial dose but not by the expression of the influenza 1918 PB1-F2 protein. Finally, our model provides a framework to investigate pathogen interaction during coinfections and to uncover dynamical differences based on inoculum size and strain.« less

Kinetics of Coinfection with Influenza A Virus and Streptococcus pneumoniae

DOE PAGES

Smith, Amber M.; Adler, Frederick R.; Ribeiro, Ruy M.; ...

2013-03-21

Secondary bacterial infections are a leading cause of illness and death during epidemic and pandemic influenza. Experimental studies suggest a lethal synergism between influenza and certain bacteria, particularly Streptococcus pneumoniae, but the precise processes involved are unclear. In this paper, to address the mechanisms and determine the influences of pathogen dose and strain on disease, we infected groups of mice with either the H1N1 subtype influenza A virus A/Puerto Rico/8/34 (PR8) or a version expressing the 1918 PB1-F2 protein (PR8-PB1-F2(1918)), followed seven days later with one of two S. pneumoniae strains, type 2 D39 or type 3 A66.1. We determinedmore » that, following bacterial infection, viral titers initially rebound and then decline slowly. Bacterial titers rapidly rise to high levels and remain elevated. We used a kinetic model to explore the coupled interactions and study the dominant controlling mechanisms. We hypothesize that viral titers rebound in the presence of bacteria due to enhanced viral release from infected cells, and that bacterial titers increase due to alveolar macrophage impairment. Dynamics are affected by initial bacterial dose but not by the expression of the influenza 1918 PB1-F2 protein. Finally, our model provides a framework to investigate pathogen interaction during coinfections and to uncover dynamical differences based on inoculum size and strain.« less

What Makes a Bacterial Species Pathogenic?:Comparative Genomic Analysis of the Genus Leptospira

PubMed Central

Fouts, Derrick E.; Matthias, Michael A.; Adhikarla, Haritha; Adler, Ben; Amorim-Santos, Luciane; Berg, Douglas E.; Bulach, Dieter; Buschiazzo, Alejandro; Chang, Yung-Fu; Galloway, Renee L.; Haake, David A.; Haft, Daniel H.; Hartskeerl, Rudy; Ko, Albert I.; Levett, Paul N.; Matsunaga, James; Mechaly, Ariel E.; Monk, Jonathan M.; Nascimento, Ana L. T.; Nelson, Karen E.; Palsson, Bernhard; Peacock, Sharon J.; Picardeau, Mathieu; Ricaldi, Jessica N.; Thaipandungpanit, Janjira; Wunder, Elsio A.; Yang, X. Frank; Zhang, Jun-Jie; Vinetz, Joseph M.

2016-01-01

Leptospirosis, caused by spirochetes of the genus Leptospira, is a globally widespread, neglected and emerging zoonotic disease. While whole genome analysis of individual pathogenic, intermediately pathogenic and saprophytic Leptospira species has been reported, comprehensive cross-species genomic comparison of all known species of infectious and non-infectious Leptospira, with the goal of identifying genes related to pathogenesis and mammalian host adaptation, remains a key gap in the field. Infectious Leptospira, comprised of pathogenic and intermediately pathogenic Leptospira, evolutionarily diverged from non-infectious, saprophytic Leptospira, as demonstrated by the following computational biology analyses: 1) the definitive taxonomy and evolutionary relatedness among all known Leptospira species; 2) genomically-predicted metabolic reconstructions that indicate novel adaptation of infectious Leptospira to mammals, including sialic acid biosynthesis, pathogen-specific porphyrin metabolism and the first-time demonstration of cobalamin (B12) autotrophy as a bacterial virulence factor; 3) CRISPR/Cas systems demonstrated only to be present in pathogenic Leptospira, suggesting a potential mechanism for this clade’s refractoriness to gene targeting; 4) finding Leptospira pathogen-specific specialized protein secretion systems; 5) novel virulence-related genes/gene families such as the Virulence Modifying (VM) (PF07598 paralogs) proteins and pathogen-specific adhesins; 6) discovery of novel, pathogen-specific protein modification and secretion mechanisms including unique lipoprotein signal peptide motifs, Sec-independent twin arginine protein secretion motifs, and the absence of certain canonical signal recognition particle proteins from all Leptospira; and 7) and demonstration of infectious Leptospira-specific signal-responsive gene expression, motility and chemotaxis systems. By identifying large scale changes in infectious (pathogenic and intermediately pathogenic

What Makes a Bacterial Species Pathogenic?:Comparative Genomic Analysis of the Genus Leptospira.

PubMed

Fouts, Derrick E; Matthias, Michael A; Adhikarla, Haritha; Adler, Ben; Amorim-Santos, Luciane; Berg, Douglas E; Bulach, Dieter; Buschiazzo, Alejandro; Chang, Yung-Fu; Galloway, Renee L; Haake, David A; Haft, Daniel H; Hartskeerl, Rudy; Ko, Albert I; Levett, Paul N; Matsunaga, James; Mechaly, Ariel E; Monk, Jonathan M; Nascimento, Ana L T; Nelson, Karen E; Palsson, Bernhard; Peacock, Sharon J; Picardeau, Mathieu; Ricaldi, Jessica N; Thaipandungpanit, Janjira; Wunder, Elsio A; Yang, X Frank; Zhang, Jun-Jie; Vinetz, Joseph M

2016-02-01

Leptospirosis, caused by spirochetes of the genus Leptospira, is a globally widespread, neglected and emerging zoonotic disease. While whole genome analysis of individual pathogenic, intermediately pathogenic and saprophytic Leptospira species has been reported, comprehensive cross-species genomic comparison of all known species of infectious and non-infectious Leptospira, with the goal of identifying genes related to pathogenesis and mammalian host adaptation, remains a key gap in the field. Infectious Leptospira, comprised of pathogenic and intermediately pathogenic Leptospira, evolutionarily diverged from non-infectious, saprophytic Leptospira, as demonstrated by the following computational biology analyses: 1) the definitive taxonomy and evolutionary relatedness among all known Leptospira species; 2) genomically-predicted metabolic reconstructions that indicate novel adaptation of infectious Leptospira to mammals, including sialic acid biosynthesis, pathogen-specific porphyrin metabolism and the first-time demonstration of cobalamin (B12) autotrophy as a bacterial virulence factor; 3) CRISPR/Cas systems demonstrated only to be present in pathogenic Leptospira, suggesting a potential mechanism for this clade's refractoriness to gene targeting; 4) finding Leptospira pathogen-specific specialized protein secretion systems; 5) novel virulence-related genes/gene families such as the Virulence Modifying (VM) (PF07598 paralogs) proteins and pathogen-specific adhesins; 6) discovery of novel, pathogen-specific protein modification and secretion mechanisms including unique lipoprotein signal peptide motifs, Sec-independent twin arginine protein secretion motifs, and the absence of certain canonical signal recognition particle proteins from all Leptospira; and 7) and demonstration of infectious Leptospira-specific signal-responsive gene expression, motility and chemotaxis systems. By identifying large scale changes in infectious (pathogenic and intermediately pathogenic

Efflux inhibitor suppresses Streptococcus mutans virulence properties.

PubMed

Zeng, Huihui; Liu, Jia; Ling, Junqi

2017-04-01

It is well established that efflux pumps play important roles in bacterial pathogenicity and efflux inhibitors (EIs) have been proved to be effective in suppressing bacterial virulence properties. However, little is known regarding the EI of Streptococcus mutans, a well-known caries-inducing bacterium. In this study, we identified the EI of S. mutans through ethidium bromide efflux assay and investigated how EI affected S. mutans virulence regarding the cariogenicity and stress response. Results indicated that reserpine, the identified EI, suppressed acid tolerance, mutacin production and transformation efficiency of S. mutans, and modified biofilm architecture and extracellular polysaccharide distribution. Suppressed glycosyltransferase activity was also noted after reserpine exposure. The data from quantitative real-time-PCR demonstrated that reserpine significantly altered the expression profile of quorum-sensing and virulence-associated genes. These findings suggest that reserpine represents a promising adjunct anticariogenic agent in that it suppresses virulence properties of S. mutans. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Water microbiology. Bacterial pathogens and water.

PubMed

Cabral, João P S

2010-10-01

Water is essential to life, but many people do not have access to clean and safe drinking water and many die of waterborne bacterial infections. In this review a general characterization of the most important bacterial diseases transmitted through water-cholera, typhoid fever and bacillary dysentery-is presented, focusing on the biology and ecology of the causal agents and on the diseases' characteristics and their life cycles in the environment. The importance of pathogenic Escherichia coli strains and emerging pathogens in drinking water-transmitted diseases is also briefly discussed. Microbiological water analysis is mainly based on the concept of fecal indicator bacteria. The main bacteria present in human and animal feces (focusing on their behavior in their hosts and in the environment) and the most important fecal indicator bacteria are presented and discussed (focusing on the advantages and limitations of their use as markers). Important sources of bacterial fecal pollution of environmental waters are also briefly indicated. In the last topic it is discussed which indicators of fecal pollution should be used in current drinking water microbiological analysis. It was concluded that safe drinking water for all is one of the major challenges of the 21st century and that microbiological control of drinking water should be the norm everywhere. Routine basic microbiological analysis of drinking water should be carried out by assaying the presence of Escherichia coli by culture methods. Whenever financial resources are available, fecal coliform determinations should be complemented with the quantification of enterococci. More studies are needed in order to check if ammonia is reliable for a preliminary screening for emergency fecal pollution outbreaks. Financial resources should be devoted to a better understanding of the ecology and behavior of human and animal fecal bacteria in environmental waters.

Water Microbiology. Bacterial Pathogens and Water

PubMed Central

Cabral, João P. S.

2010-01-01

Water is essential to life, but many people do not have access to clean and safe drinking water and many die of waterborne bacterial infections. In this review a general characterization of the most important bacterial diseases transmitted through water—cholera, typhoid fever and bacillary dysentery—is presented, focusing on the biology and ecology of the causal agents and on the diseases’ characteristics and their life cycles in the environment. The importance of pathogenic Escherichia coli strains and emerging pathogens in drinking water-transmitted diseases is also briefly discussed. Microbiological water analysis is mainly based on the concept of fecal indicator bacteria. The main bacteria present in human and animal feces (focusing on their behavior in their hosts and in the environment) and the most important fecal indicator bacteria are presented and discussed (focusing on the advantages and limitations of their use as markers). Important sources of bacterial fecal pollution of environmental waters are also briefly indicated. In the last topic it is discussed which indicators of fecal pollution should be used in current drinking water microbiological analysis. It was concluded that safe drinking water for all is one of the major challenges of the 21st century and that microbiological control of drinking water should be the norm everywhere. Routine basic microbiological analysis of drinking water should be carried out by assaying the presence of Escherichia coli by culture methods. Whenever financial resources are available, fecal coliform determinations should be complemented with the quantification of enterococci. More studies are needed in order to check if ammonia is reliable for a preliminary screening for emergency fecal pollution outbreaks. Financial resources should be devoted to a better understanding of the ecology and behavior of human and animal fecal bacteria in environmental waters. PMID:21139855

[Plasticity of bacterial genomes: pathogenicity islands and the locus of enterocyte effacement (LEE)].

PubMed

Kirsch, Petra; Jores, Jörg; Wieler, Lothar H

2004-01-01

Many bacterial virulence attributes, like toxins, adhesins, invasins, iron uptake systems, are encoded within specific regions of the bacterial genome. These in size varying regions are termed pathogenicity islands (PAIs) since they confer pathogenic properties to the respective micro-organism. Per definition PAIs are exclusively found in pathogenic strains and are often inserted near transfer-RNA genes. Nevertheless, non-pathogenic bacteria also possess foreign DNA elements that confer advantageous features, leading to improved fitness. These additional DNA elements as well as PAIs are termed genomic islands and were acquired during bacterial evolution. Significant G+C content deviation in pathogenicity islands with respect to the rest of the genome, the presence of direct repeat sequences at the flanking regions, the presence of integrase gene determinants as other mobility features,the particular insertion site (tRNA gene) as well as the observed genetic instability suggests that pathogenicity islands were acquired by horizontal gene transfer. PAIs are the fascinating proof of the plasticity of bacterial genomes. PAIs were originally described in human pathogenic Escherichia (E.) coli strains. In the meantime PAIs have been found in various pathogenic bacteria of humans, animals and even plants. The Locus of Enterocyte Effacement (LEE) is one particular widely distributed PAI of E coli. In addition, it also confers pathogenicity to the related species Citrobacter (C.) rodentium and Escherichia (E.) alvei. The LEE is an important virulence feature of several animal pathogens. It is an obligate PAI of all animal and human enteropathogenic E. coli (EPEC), and most enterohaemorrhegic E. coli (EHEC) also harbor the LEE. The LEE encodes a type III secretion system, an adhesion (intimin) that mediates the intimate contact between the bacterium and the epithelial cell, as well as various proteins which are secreted via the type III secretion system. The LEE encoded

Investigation for zoonotic disease pathogens (Aeromonas hydrophila, Pseudomonas fluorescens, Streptococcus iniae) seen in carp farms in Duhok region of Northern Iraq by molecular methods

NASA Astrophysics Data System (ADS)

Mohammed, Kamiran Abdulrahman; Arabacı, Muhammed; Önalan, Şükrü

2017-04-01

The aim of this study was to determine the zoonotic bacteria in carp farms in Duhok region of the Northern Iraq. Carp is the main fish species cultured in the Duhok region. The most common zoonotic bacteria generally seen in carp farms are Aeromonas hydrophila, Pseudomonas fluorescens and Streptococcus iniae. Samples were collected from 20 carp farms in the Duhok Region of the Northern Iraq. Six carp samples were collected from each carp farm. Head kidney tissue samples and intestine tissue samples were collected from each carp sample. Than head kidney and intestine tissue samples were pooled. The total bacterial DNA extraction from the pooled each 20 head kidney tissue samples and pooled each 20 intestinal tissue samples. Primers for pathogens were originally designed from 16S Ribosomal gene region. Zoonotic bacteria were scanned in all tissue samples by absent / present analysis in the RT-PCR. After RT-PCR, Capillary gel electrophoresis bands were used for the confirmation of the size of amplicon which was planned during primer designing stage. As a result, one sample was positive in respect to Aeromonas hydrophila, from intestine and one carp farm was positive in respect to Pseudomonas fluorescens from intestine and two carp farms were positive in respect to Streptococcus iniae. Totally 17 of 20 carp farms were negative in respect to the zoonotic bacteria. In conclusion the zoonotic bacteria were very low (15 %) in carp farms from the Duhok Region in the Northern Iraq. Only in one Carp farms, both Aeromonas hydrophila and Pseudomonas fluorescens were positive. Also Streptococcus inia were positive in two carp farms.

Inhibitory activity of a standardized elderberry liquid extract against clinically-relevant human respiratory bacterial pathogens and influenza A and B viruses

PubMed Central

2011-01-01

Background Black elderberries (Sambucus nigra L.) are well known as supportive agents against common cold and influenza. It is further known that bacterial super-infection during an influenza virus (IV) infection can lead to severe pneumonia. We have analyzed a standardized elderberry extract (Rubini, BerryPharma AG) for its antimicrobial and antiviral activity using the microtitre broth micro-dilution assay against three Gram-positive bacteria and one Gram-negative bacteria responsible for infections of the upper respiratory tract, as well as cell culture experiments for two different strains of influenza virus. Methods The antimicrobial activity of the elderberry extract was determined by bacterial growth experiments in liquid cultures using the extract at concentrations of 5%, 10%, 15% and 20%. The inhibitory effects were determined by plating the bacteria on agar plates. In addition, the inhibitory potential of the extract on the propagation of human pathogenic H5N1-type influenza A virus isolated from a patient and an influenza B virus strain was investigated using MTT and focus assays. Results For the first time, it was shown that a standardized elderberry liquid extract possesses antimicrobial activity against both Gram-positive bacteria of Streptococcus pyogenes and group C and G Streptococci, and the Gram-negative bacterium Branhamella catarrhalis in liquid cultures. The liquid extract also displays an inhibitory effect on the propagation of human pathogenic influenza viruses. Conclusion Rubini elderberry liquid extract is active against human pathogenic bacteria as well as influenza viruses. The activities shown suggest that additional and alternative approaches to combat infections might be provided by this natural product. PMID:21352539

Minimization of bacterial size allows for complement evasion and is overcome by the agglutinating effect of antibody

PubMed Central

Dalia, Ankur B.; Weiser, Jeffrey N.

2011-01-01

SUMMARY The complement system, which functions by lysing pathogens directly or by promoting their uptake by phagocytes, is critical for controlling many microbial infections. Here we show that in Streptococcus pneumoniae, increasing bacterial chain length sensitizes this pathogen to complement deposition and subsequent uptake by human neutrophils. Consistent with this, we show that minimizing chain length provides wild-type bacteria with a competitive advantage in vivo in a model of systemic infection. Investigating how the host overcomes this virulence strategy, we find that antibody promotes complement-dependent opsonophagocytic killing of Streptococcus pneumoniae and lysis of Haemophilus influenzae independent of Fc-mediated effector functions. Consistent with the agglutinating effect of antibody, F(ab′)2 but not Fab could promote this effect. Therefore, increasing pathogen size, whether by natural changes in cellular morphology or via antibody-mediated agglutination, promotes complement-dependent killing. These observations have broad implications for how cell size and morphology can affect virulence among pathogenic microbes. PMID:22100164

Antibodies Reactive to Commensal Streptococcus mitis Show Cross-Reactivity With Virulent Streptococcus pneumoniae Serotypes.

PubMed

Shekhar, Sudhanshu; Khan, Rabia; Ferreira, Daniela M; Mitsi, Elena; German, Esther; Rørvik, Gro Herredsvela; Berild, Dag; Schenck, Karl; Kwon, Keehwan; Petersen, Fernanda

2018-01-01

Current vaccines against Streptococcus pneumoniae , a bacterial species that afflicts people by causing a wide spectrum of diseases, do not protect against all pneumococcal serotypes. Thus, alternative vaccines to fight pneumococcal infections that target common proteins are under investigation. One promising strategy is to take advantage of immune cross-reactivity between commensal and pathogenic microbes for cross-protection. In this study, we examined the antibody-mediated cross-reactivity between S. pneumoniae and Streptococcus mitis , a commensal species closely related to S. pneumoniae . Western blot analysis showed that rabbit antisera raised against S. mitis reacted with multiple proteins of virulent S. pneumoniae strains (6B, TIGR4, and D39). Rabbit anti- S. pneumoniae IgG antibodies also showed binding to S. mitis antigens. Incubation of rabbit antisera raised against S. mitis with heterologous or homologous bacterial lysates resulted in marked inhibition of the developments of bands in the Western blots. Furthermore, plasma IgG antibodies from adult human volunteers intranasally inoculated with S. pneumoniae 6B revealed enhanced S. mitis -specific IgG titers compared with the pre-inoculation samples. Using an on-chip protein microarray representing a number of selected membrane and extracellular S. pneumoniae proteins, we identified choline-binding protein D (CbpD), cell division protein (FtsH), and manganese ABC transporter or manganese-binding adhesion lipoprotein (PsaA) as common targets of the rabbit IgG antibodies raised against S. mitis or S. pneumoniae . Cumulatively, these findings provide evidence on the antibody-mediated cross-reactivity of proteins from S. mitis and S. pneumoniae , which may have implications for development of effective and wide-range pneumococcal vaccines.

The FUN of identifying gene function in bacterial pathogens; insights from Salmonella functional genomics.

PubMed

Hammarlöf, Disa L; Canals, Rocío; Hinton, Jay C D

2013-10-01

The availability of thousands of genome sequences of bacterial pathogens poses a particular challenge because each genome contains hundreds of genes of unknown function (FUN). How can we easily discover which FUN genes encode important virulence factors? One solution is to combine two different functional genomic approaches. First, transcriptomics identifies bacterial FUN genes that show differential expression during the process of mammalian infection. Second, global mutagenesis identifies individual FUN genes that the pathogen requires to cause disease. The intersection of these datasets can reveal a small set of candidate genes most likely to encode novel virulence attributes. We demonstrate this approach with the Salmonella infection model, and propose that a similar strategy could be used for other bacterial pathogens. Copyright © 2013 Elsevier Ltd. All rights reserved.

Plant immunity: a lesson from pathogenic bacterial effector proteins.

PubMed

Cui, Haitao; Xiang, Tingting; Zhou, Jian-Min

2009-10-01

Phytopathogenic bacteria inject an array of effector proteins into host cells to alter host physiology and assist the infection process. Some of these effectors can also trigger disease resistance as a result of recognition in the plant cell by cytoplasmic immune receptors. In addition to effector-triggered immunity, plants immunity can be triggered upon the detection of Pathogen/Microbe-Associated Molecular Patterns by surface-localized immune receptors. Recent progress indicates that many bacterial effector proteins use a variety of biochemical properties to directly attack key components of PAMP-triggered immunity and effector-triggered immunity, providing new insights into the molecular basis of plant innate immunity. Emerging evidence indicate that the evolution of disease resistance in plants is intimately linked to the mechanism by which bacterial effectors promote parasitism. This review focuses on how these studies have conceptually advanced our understanding of plant-pathogen interactions.

Of the Phrensy: an update on the epidemiology and pathogenesis of bacterial meningitis in the pediatric population.

PubMed

Janowski, Andrew; Newland, Jason

2017-01-01

In the past century, advances in antibiotics and vaccination have dramatically altered the incidence and clinical outcomes of bacterial meningitis. We review the shifting epidemiology of meningitis in children, including after the implementation of vaccines that target common meningitic pathogens and the introduction of intrapartum antibiotic prophylaxis offered to mothers colonized with Streptococcus agalactiae . We also discuss what is currently known about the pathogenesis of meningitis. Recent studies of the human microbiome have illustrated dynamic relationships of bacterial and viral populations with the host, which may potentiate the risk of bacterial meningitis.

Subverting Toll-Like Receptor Signaling by Bacterial Pathogens

PubMed Central

McGuire, Victoria A.; Arthur, J. Simon C.

2015-01-01

Pathogenic bacteria are detected by pattern-recognition receptors (PRRs) expressed on innate immune cells, which activate intracellular signal transduction pathways to elicit an immune response. Toll-like receptors are, perhaps, the most studied of the PRRs and can activate the mitogen-activated protein kinase (MAPK) and Nuclear Factor-κB (NF-κB) pathways. These pathways are critical for mounting an effective immune response. In order to evade detection and promote virulence, many pathogens subvert the host immune response by targeting components of these signal transduction pathways. This mini-review highlights the diverse mechanisms that bacterial pathogens have evolved to manipulate the innate immune response, with a particular focus on those that target MAPK and NF-κB signaling pathways. Understanding the elaborate strategies that pathogens employ to subvert the immune response not only highlights the importance of these proteins in mounting effective immune responses, but may also identify novel approaches for treatment or prevention of infection. PMID:26648936

In vitro activity of Ceftaroline against bacterial pathogens isolated from patients with skin and soft tissue and respiratory tract infections in African and Middle Eastern countries: AWARE global surveillance program 2012-2014.

PubMed

Karlowsky, James A; Biedenbach, Douglas J; Bouchillon, Samuel K; Hackel, Meredith; Iaconis, Joseph P; Sahm, Daniel F

2016-10-01

The objective of this report was to document antimicrobial susceptibility testing surveillance data for ceftaroline and comparative agents from the AWARE (Assessing Worldwide Antimicrobial Resistance Evaluation) global surveillance program for bacterial pathogens causing skin and soft tissue and respiratory tract infections in African and Middle Eastern countries from 2012 through 2014. Pathogen identities were confirmed by MALDI-TOF and antimicrobial susceptibility testing performed by CLSI broth microdilution methodology in a central laboratory. All methicillin-susceptible Staphylococcus aureus (MSSA) (n= 923; MIC90, 0.25 μg/mL) and 91.8% of methicillin-resistant S. aureus (MRSA) (n= 1161; MIC90, 1 μg/mL) tested were susceptible to ceftaroline. The maximum ceftaroline MIC observed for isolates of MRSA was 2 μg/mL. All Streptococcus pyogenes (n= 174; MIC90, 0.008 μg/mL), Streptococcus agalactiae (n= 44; MIC90, 0.015 μg/mL), Streptococcus pneumoniae (n= 351; MIC90, 0.25 μg/mL), and Haemophilus influenzae (n= 84; MIC90, ≤0.015 μg/mL) were susceptible to ceftaroline. Rates of susceptibility to ceftaroline among ESBL-negative Escherichia coli (n= 338), Klebsiella pneumoniae (n= 241), and Klebsiella oxytoca (n= 97) were 89.1% (MIC90, 1 μg/mL), 94.2% (MIC90, 0.5 μg/mL), and 99.0% (MIC90, 0.5 μg/mL), respectively. Copyright © 2016. Published by Elsevier Inc.

Prospective multi-centre sentinel surveillance for Haemophilus influenzae type b & other bacterial meningitis in Indian children.

PubMed

Ramachandran, Padmanabhan; Fitzwater, Sean Patrick; Aneja, Satinder; Verghese, Valsan Philip; Kumar, Vishwajeet; Nedunchelian, Krishnamoorthy; Wadhwa, Nitya; Veeraraghavan, Balaji; Kumar, Rashmi; Meeran, Mohamed; Kapil, Arti; Jasmine, Sudha; Kumar, Aarti; Suresh, Saradha; Bhatnagar, Shinjini; Thomas, Kurien; Awasthi, Shally; Santosham, Mathuram; Chandran, Aruna

2013-04-01

Haemophilus influenzae type b (Hib) is one of the leading bacterial causes of invasive disease in populations without access to Hib conjugate vaccines (Hib-CV). India has recently decided to introduce Hib-CV into the routine immunization programme in selected States. Longitudinal data quantifying the burden of bacterial meningitis and the proportion of disease caused by various bacteria are needed to track the impact of Hib-CV once introduced. A hospital-based sentinel surveillance network was established at four places in the country and this study reports the results of this ongoing surveillance. Children aged 1 to 23 months with suspected bacterial meningitis were enrolled in Chennai, Lucknow, New Delhi, and Vellore between July 2008 and June 2010. All cerebrospinal fluid (CSF) samples were tested using cytological, biochemical, and culture methods. Samples with abnormal CSF (≥10 WBC per μl) were tested by latex agglutination test for common paediatric bacterial meningitis pathogens. A total of 708 patients with abnormal CSF were identified, 89 of whom had a bacterial pathogen confirmed. Hib accounted for the majority of bacteriologically confirmed cases, 62 (70%), while Streptococcus pneumoniae and group B Streptococcus were identified in 12 (13%) and seven (8%) cases, respectively. The other eight cases were a mix of other bacteria. The proportion of abnormal CSF and probable bacterial meningitis that was caused by Hib was 74 and 58 per cent lower at Christian Medical College (CMC), Vellore, which had a 41 per cent coverage of Hib-CV among all suspected meningitis cases, compared to the combined average proportion at the other three centres where a coverage between 1 and 8 per cent was seen (P<0.001 and P= 0.05, respectively). Hib was found to be the predominant cause of bacterial meningitis in young children in diverse geographic locations in India. Possible indications of herd immunity was seen at CMC compared to sites with low immunization coverage with

Metabolic Mechanism for l-Leucine-Induced Metabolome To Eliminate Streptococcus iniae.

PubMed

Du, Chao-Chao; Yang, Man-Jun; Li, Min-Yi; Yang, Jun; Peng, Bo; Li, Hui; Peng, Xuan-Xian

2017-05-05

Crucial metabolites that modulate hosts' metabolome to eliminate bacterial pathogens have been documented, but the metabolic mechanisms are largely unknown. The present study explores the metabolic mechanism for l-leucine-induced metabolome to eliminate Streptococcus iniae in tilapia. GC-MS-based metabolomics was used to investigate the tilapia liver metabolic profile in the presence of exogenous l-leucine. Thirty-seven metabolites of differential abundance were determined, and 11 metabolic pathways were enriched. Pattern recognition analysis identified serine and proline as crucial metabolites, which are the two metabolites identified in survived tilapias during S. iniae infection, suggesting that the two metabolites play crucial roles in l-leucine-induced elimination of the pathogen by the host. Exogenous l-serine reduces the mortality of tilapias infected by S. iniae, providing a robust proof supporting the conclusion. Furthermore, exogenous l-serine elevates expression of genes IL-1β and IL-8 in tilapia spleen, but not TNFα, CXCR4 and Mx, suggesting that the metabolite promotes a phagocytosis role of macrophages, which is consistent with the finding that l-leucine promotes macrophages to kill both Gram-positive and Gram-negative bacterial pathogens. Therefore, the ability of phagocytosis enhanced by exogenous l-leucine is partly attributed to elevation of l-serine. These results demonstrate a metabolic mechanism by which exogenous l-leucine modulates tilapias' metabolome to enhance innate immunity and eliminate pathogens.

Genome-based approaches to develop vaccines against bacterial pathogens.

PubMed

Serruto, Davide; Serino, Laura; Masignani, Vega; Pizza, Mariagrazia

2009-05-26

Bacterial infectious diseases remain the single most important threat to health worldwide. Although conventional vaccinology approaches were successful in conferring protection against several diseases, they failed to provide efficacious solutions against many others. The advent of whole-genome sequencing changed the way to think about vaccine development, enabling the targeting of possible vaccine candidates starting from the genomic information of a single bacterial isolate, with a process named reverse vaccinology. As the genomic era progressed, reverse vaccinology has evolved with a pan-genome approach and multi-strain genome analysis became fundamental for the design of universal vaccines. This review describes the applications of genome-based approaches in the development of new vaccines against bacterial pathogens.

Electrochemical Biosensor for Rapid and Sensitive Detection of Magnetically Extracted Bacterial Pathogens

PubMed Central

Setterington, Emma B.; Alocilja, Evangelyn C.

2012-01-01

Biological defense and security applications demand rapid, sensitive detection of bacterial pathogens. This work presents a novel qualitative electrochemical detection technique which is applied to two representative bacterial pathogens, Bacillus cereus (as a surrogate for B. anthracis) and Escherichia coli O157:H7, resulting in detection limits of 40 CFU/mL and 6 CFU/mL, respectively, from pure culture. Cyclic voltammetry is combined with immunomagnetic separation in a rapid method requiring approximately 1 h for presumptive positive/negative results. An immunofunctionalized magnetic/polyaniline core/shell nano-particle (c/sNP) is employed to extract target cells from the sample solution and magnetically position them on a screen-printed carbon electrode (SPCE) sensor. The presence of target cells significantly inhibits current flow between the electrically active c/sNPs and SPCE. This method has the potential to be adapted for a wide variety of target organisms and sample matrices, and to become a fully portable system for routine monitoring or emergency detection of bacterial pathogens. PMID:25585629

[Bacterial meningitis].

PubMed

Brouwer, M C; van de Beek, D

2012-05-01

Bacterial meningitis is a severe disease which affects 35.000 Europeans each year and has a mortality rate of about 20%. During the past 25 years the epidemiology of bacterial meningitis has changed significantly due to the implementation of vaccination against Haemophilus influenzae, Neisseria meningtidis group C and Streptococcus pneumoniae. Due to these vaccines, meningitis is now predominantly a disease occurring in adults, caused especially by Streptococcus pneumoniae, while it was formerly a child disease which was largely caused by Haemophilus influenzae. Bacterial meningitis is often difficult to recognize since the classical presentation with neck stiffness, reduced awareness and fever occurs in less than half of the patients. The only way to diagnose or exclude bacterial meningitis is by performing low-threshold cerebrospinal fluid examination with a suspicion of bacterial meningitis. The treatment consists of the prescription of antibiotics and dexamethasone.

A streptococcal NRAMP homologue is crucial for the survival of Streptococcus agalactiae under low pH conditions.

PubMed

Shabayek, Sarah; Bauer, Richard; Mauerer, Stefanie; Mizaikoff, Boris; Spellerberg, Barbara

2016-05-01

Streptococcus agalactiae or Group B Streptococcus (GBS) is a commensal bacterium of the human gastrointestinal and urogenital tracts as well as a leading cause of neonatal sepsis, pneumonia and meningitis. Maternal vaginal carriage is the main source for GBS transmission and thus the most important risk factor for neonatal disease. Several studies in eukaryotes identified a group of proteins natural resistance-associated macrophage protein (NRAMP) that function as divalent cation transporters for Fe(2+) and Mn(2+) and confer on macrophages the ability to control replication of bacterial pathogens. Genome sequencing predicted potential NRAMP homologues in several prokaryotes. Here we describe for the first time, a pH-regulated NRAMP Mn(2+) /Fe(2+) transporter in GBS, designated MntH, which confers resistance to reactive oxygen species (ROS) and is crucial for bacterial growth and survival under low pH conditions. Our investigation implicates MntH as an important colonization determinant for GBS in the maternal vagina as it helps bacteria to adapt to the harsh acidic environment, facilitates bacterial adherence, contributes to the coexistence with the vaginal microbiota and plays a role in GBS intracellular survival inside macrophages. © 2016 John Wiley & Sons Ltd.

Etiology of acute otitis media and serotype distribution of Streptococcus pneumoniae and Haemophilus influenzae in Chilean children <5 years of age

PubMed Central

Rosenblut, Andres; Napolitano, Carla; Pereira, Angelica; Moreno, Camilo; Kolhe, Devayani; Lepetic, Alejandro; Ortega-Barria, Eduardo

2017-01-01

Abstract The impact of bacterial conjugate vaccines on acute otitis media (AOM) is affected by several factors including population characteristics, bacterial etiology and vaccine conjugation method, carrier, and coverage. This study estimated the baseline etiology, distribution, and antibiotic susceptibility of bacterial serotypes that causes AOM in children aged <5 years in a public setting in Santiago, Chile. Children aged ≥3 months and <5 years referred to the physician for treatment of AOM episodes (with an onset of symptoms <72 h) were enrolled between September 2009 and September 2010. Middle ear fluid (MEF) was collected by tympanocentesis or by otorrhea for identification and serotyping of bacteria. Antibacterial susceptibility was tested using E-test (etrack: 112671). Of 160 children (mean age 27.10 ± 15.83 months) with AOM episodes, 164 MEF samples (1 episode each from 156 children; 2 episodes each from 4 children) were collected. Nearly 30% of AOM episodes occurred in children aged 12 to 23 months. Streptococcus pneumoniae (41.7% [58/139]) and Haemophilus influenzae (40.3% [56/139]) were predominant among the cultures that showed bacterial growth (85% [139/164]). All Streptococcus pneumoniae positive episodes were serotyped, 19F (21%) and 14 (17%) were the predominant serotypes; all Haemophilus influenzae strains were nontypeable. Streptococcus pneumoniae were resistant to penicillin (5%) and erythromycin (33%); Haemophilus influenzae were resistant to ampicillin (14%) and cefuroxime and cefotaxime (2% each). AOM in Chilean children is predominantly caused by Streptococcus pneumoniae and nontypeable Haemophilus influenzae. Use of a broad spectrum vaccine against these pathogens might aid the reduction of AOM in Chile. PMID:28178138

GROUP B STREPTOCOCCUS: PREVALENCE IN A NON-OBSTETRIC POPULATION

PubMed Central

LECLAIR, Catherine M.; HART, Ashley E.; GOETSCH, Martha F.; CARPENTIER, Heather; JENSEN, Jeffrey T.

2010-01-01

Objective: To establish and compare the prevalence of Group B streptococcus (GBS) colonization in the vaginas of non-obstetric women with and without vaginitis. Materials and Methods: Cross-sectional analysis Group B streptococcus vaginal culture status of non-pregnant, estrogen-replete women ≥18 years presenting for annual gynecological exams or vaginal infection. Subjects were classified into 3 groups: no vaginitis (NV) if symptoms were absent and exam was normal, common vaginitis (CV) if microscopic exam revealed yeast, bacterial vaginosis or trichomonads, or inflammatory vaginitis (IV) if exam revealed inflammation and immature squamous cells, but no pathogens. Results: Of the 215 women recruited: 147 (68.4%) showed no evidence of vaginitis, 41 (19.1%) had CV, and 27 (12.6%) showed evidence of IV. The overall prevalence rate of GBS was 22.8%. Vaginitis was associated with a significantly increased risk of GBS colonization [Adjusted OR: CV 2.7 (1.1-6.2); IV 2.9 (1.1-8.0)]. Logistic regression revealed pH >4.5, presence of abnormal discharge on exam and a women's complaint of current symptoms to be significant predicators of the presence of GBS. Conclusion: GBS colonization occurs more commonly in women with vaginitis. This suggests that disruption of the normal vaginal bacterial environment is an important predictor for GBS colonization. PMID:20592549

Diethylaminoethyl-cellulose-bacterial cell immunoadsorbent columns: preparation of serotype-specific globulin and immunofluorescent conjugates for Streptococcus mutans serotypes a and d.

PubMed

McKinney, R M; Thacker, L

1976-04-01

Diethylaminoethyl (DEAE)-cellulose was used as a support material for preparing bacterial cell columns. Pretreatment of the bacterial cells with formalin was essential in obtaining satisfactory adherence of the cells to DEAE-cellulose. Cross-reacting antibodies were removed from antibody preparations against strains of Streptococcus mutans serotypes a and d by adsorption on appropriate bacterial cell columns. S. mutans serotype d was further divided into two subtypes on the basis of immunofluorescent staining with conjugates of immunospecifically adsorbed immunoglobulin G. The DEAE-cellulose-bacterial cell columns were regenerated after use by desorbing the cross-reacting antibodies with low-pH buffer and were used repeatedly over and 18-month period with no detectable loss in effectiveness.

Within-herd prevalence thresholds for herd-level detection of mastitis pathogens using multiplex real-time PCR in bulk tank milk samples.

PubMed

Soltau, J B; Einax, E; Klengel, K; Katholm, J; Failing, K; Wehrend, A; Donat, K

2017-10-01

The objective of the study was to assess the value of quantitative multiplex real-time PCR examination of bulk tank milk samples for bovine mastitis pathogens as a tool for herd level diagnosis. Using a logistic regression model, this study is aimed at calculating the threshold level of the apparent within-herd prevalence as determined by quarter milk sample cultivation of all lactating cows, thus allowing the detection of a herd positive for a specific pathogen within certain probability levels. A total of 6,335 quarter milk samples were collected and cultured from 1,615 cows on 51 farms in Germany. Bulk tank milk samples were taken from each farm and tested by bacterial culture as well as the commercial PCR assay Mastit 4A (DNA Diagnostic A/S, Risskov, Denmark) identifying Staphylococcus aureus, Streptococcus dysgalactiae, Streptococcus agalactiae, and Streptococcus uberis. In addition, PCR was performed on pooled herd milk samples containing milk aliquots from all lactating cows in each of the 51 herds. Only 1 out of the 51 herds was found PCR positive for Streptococcus agalactiae in bulk tank and pooled herd milk samples, and cultured quarter milk samples. Spearman's rank correlations between the cycle threshold value of bulk tank milk PCR and the apparent within-herd prevalence were calculated in regard to Staphylococcus aureus, Streptococcus dysgalactiae, and Streptococcus uberis. For these pathogens, significant correlations were found. If 1 bulk tank milk sample per herd was tested, the estimated within-herd prevalence thresholds for 90% probability of detection were 27.6% for Staphylococcus aureus, 9.2% for Streptococcus dysgalactiae, and 13.8% for Streptococcus uberis on the cow level. On the quarter level, the within-herd prevalence had to be at least 32.6% for Staphylococcus aureus, 1.7% for Streptococcus dysgalactiae, and 4.3% for Streptococcus uberis to detect a herd as positive using a single bulk milk sample. The results indicate that mastitis

Incidence of clinical mastitis and distribution of pathogens on large Chinese dairy farms.

PubMed

Gao, Jian; Barkema, Herman W; Zhang, Limei; Liu, Gang; Deng, Zhaoju; Cai, Lingjie; Shan, Ruixue; Zhang, Shiyao; Zou, Jiaqi; Kastelic, John P; Han, Bo

2017-06-01

Knowledge of the incidence of clinical mastitis (CM) and the distribution of pathogens involved is essential for development of prevention and control programs as well as treatment protocols. No country-wide study on the incidence of CM and the distribution of pathogens involved has been conducted in China. Core objectives of this study were, therefore, to determine the cumulative incidence of CM and the distribution of pathogens causing CM on large Chinese (>500 cows) dairy farms. In addition, associations between the distribution of CM pathogens and bedding materials and seasonal factors were also investigated. Bacterial culture was done on a total of 3,288 CM quarter milk samples from 161 dairy herds (located in 21 provinces) between March 2014 and September 2016. Additional data, including geographical region of herds, herd size, bedding types, and number of CM cases during the last month, were also recorded. Mean cumulative incidence of CM was 3.3 cases per 100 cows per month (range = 1.7 to 8.1). The most frequently isolated pathogens were Escherichia coli (14.4%), Klebsiella spp. (13.0%), coagulase-negative staphylococci (11.3%), Streptococcus dysgalactiae (10.5%), and Staphylococcus aureus (10.2%). Streptococcus agalactiae was isolated from 2.8% of CM samples, whereas Streptococcus uberis were isolated from 2.1% of samples, and 15.8% of 3,288 samples were culture-negative. Coagulase-negative staphylococci, E. coli, and other Enterobacter spp. were more frequently isolated in the northwest than the northeast or south of China. Streptococcus dysgalactiae, other streptococci, and Strep. agalactiae were more frequently isolated in winter (October-March), whereas E. coli and Klebsiella spp. were mostly isolated in summer (April-September). Streptococcus dysgalactiae was more often isolated from CM cases of herds using sand bedding, whereas Klebsiella spp. and other streptococci were more common in herds using organic bedding. The incidence of CM and distribution

Prevalence of bloodstream pathogens is higher in neonatal encephalopathy cases vs. controls using a novel panel of real-time PCR assays.

PubMed

Tann, Cally J; Nkurunziza, Peter; Nakakeeto, Margaret; Oweka, James; Kurinczuk, Jennifer J; Were, Jackson; Nyombi, Natasha; Hughes, Peter; Willey, Barbara A; Elliott, Alison M; Robertson, Nicola J; Klein, Nigel; Harris, Kathryn A

2014-01-01

In neonatal encephalopathy (NE), infectious co-morbidity is difficult to diagnose accurately, but may increase the vulnerability of the developing brain to hypoxia-ischemia. We developed a novel panel of species-specific real-time PCR assays to identify bloodstream pathogens amongst newborns with and without NE in Uganda. Multiplex real-time PCR assays for important neonatal bloodstream pathogens (gram positive and gram negative bacteria, cytomegalovirus (CMV), herpes simplex virus(HSV) and P. falciparum) were performed on whole blood taken from 202 encephalopathic and 101 control infants. Automated blood culture (BACTEC) was performed for all cases and unwell controls. Prevalence of pathogenic bacterial species amongst infants with NE was 3.6%, 6.9% and 8.9%, with culture, PCR and both tests in combination, respectively. More encephalopathic infants than controls had pathogenic bacterial species detected (8.9%vs2.0%, p = 0.028) using culture and PCR in combination. PCR detected bacteremia in 11 culture negative encephalopathic infants (3 Group B Streptococcus, 1 Group A Streptococcus, 1 Staphylococcus aureus and 6 Enterobacteriacae). Coagulase negative staphylococcus, frequently detected by PCR amongst case and control infants, was considered a contaminant. Prevalence of CMV, HSV and malaria amongst cases was low (1.5%, 0.5% and 0.5%, respectively). This real-time PCR panel detected more bacteremia than culture alone and provides a novel tool for detection of neonatal bloodstream pathogens that may be applied across a range of clinical situations and settings. Significantly more encephalopathic infants than controls had pathogenic bacterial species detected suggesting that infection may be an important risk factor for NE in this setting.

Acute meningitis of piglets and mice caused by co-infected with Streptococcus suis and Aerococcus viridans.

PubMed

Pan, Zihao; Ma, Ye; Ma, Jiale; Dong, Wenyang; Yao, Huochun

2017-05-01

The two opportunistic pathogens, Streptococcus suis (S. suis) and Aerococcus. viridans (A. viridans) were isolated from the brains of piglets suffered bacterial meningitis in a farm of China. The murine model has been established to evaluate the pathogenicity and symbiotic relationship of S. suis and A. viridans simultaneously infection. Our results demonstrated the ability of new serotype S. suis to cause the classical bacterial meningitis and death were greatly enhanced during co-infection with A. viridans in mice at a proportion. We also examined the distribution and titer of bacteria coinfection in organs, the titer of S. suis appeared a significant trend for an increase in the lung meanwhile the concentration titer of A. viridans maintain a low level. This is the first reported the A. viridans and S. suis coinfection cause the bacterial meningitis outbroke in the piglets and mice. Moreover, further investigation of the pathogenesis of A. viridans and S. suis is urgently needed in swine industry. Copyright © 2016 Elsevier Ltd. All rights reserved.

Shared and distinct mechanisms of iron acquisition by bacterial and fungal pathogens of humans

PubMed Central

Caza, Mélissa; Kronstad, James W.

2013-01-01

Iron is the most abundant transition metal in the human body and its bioavailability is stringently controlled. In particular, iron is tightly bound to host proteins such as transferrin to maintain homeostasis, to limit potential damage caused by iron toxicity under physiological conditions and to restrict access by pathogens. Therefore, iron acquisition during infection of a human host is a challenge that must be surmounted by every successful pathogenic microorganism. Iron is essential for bacterial and fungal physiological processes such as DNA replication, transcription, metabolism, and energy generation via respiration. Hence, pathogenic bacteria and fungi have developed sophisticated strategies to gain access to iron from host sources. Indeed, siderophore production and transport, iron acquisition from heme and host iron-containing proteins such as hemoglobin and transferrin, and reduction of ferric to ferrous iron with subsequent transport are all strategies found in bacterial and fungal pathogens of humans. This review focuses on a comparison of these strategies between bacterial and fungal pathogens in the context of virulence and the iron limitation that occurs in the human body as a mechanism of innate nutritional defense. PMID:24312900

Application of a bacteriophage lysin to disrupt biofilms formed by the animal pathogen Streptococcus suis.

PubMed

Meng, Xiangpeng; Shi, Yibo; Ji, Wenhui; Meng, Xueling; Zhang, Jing; Wang, Hengan; Lu, Chengping; Sun, Jianhe; Yan, Yaxian

2011-12-01

Bacterial biofilms are crucial to the pathogenesis of many important infections and are difficult to eradicate. Streptococcus suis is an important pathogen of pigs, and here the biofilm-forming ability of 32 strains of this species was determined. Significant biofilms were completely formed by 10 of the strains after 60 h of incubation, with exopolysaccharide production in the biofilm significantly higher than that in the corresponding planktonic cultures. S. suis strain SS2-4 formed a dense biofilm, as revealed by scanning electron microscopy, and in this state exhibited increased resistance to a number of antibiotics (ampicillin, amoxicillin, ciprofloxacin, kanamycin, and rifampin) compared to that of planktonic cultures. A bacteriophage lysin, designated LySMP, was used to attack biofilms alone and in combination with antibiotics and bacteriophage. The results demonstrated that the biofilms formed by S. suis, especially strains SS2-4 and SS2-H, could be dispersed by LySMP and with >80% removal compared to a biofilm reduction by treatment with either antibiotics or bacteriophage alone of less than 20%; in addition to disruption of the biofilm structure, the S. suis cells themselves were inactivated by LySMP. The efficacy of LySMP was not dose dependent, and in combination with antibiotics, it acted synergistically to maximize dispersal of the S. suis biofilm and inactivate the released cells. These data suggest that bacteriophage lysin could form part of an effective strategy to treat S. suis infections and represents a new class of antibiofilm agents.

Phylogenomic and MALDI-TOF MS Analysis of Streptococcus sinensis HKU4T Reveals a Distinct Phylogenetic Clade in the Genus Streptococcus

PubMed Central

Tse, Herman; Chen, Jonathan H.K.; Tang, Ying; Lau, Susanna K.P.; Woo, Patrick C.Y.

2014-01-01

Streptococcus sinensis is a recently discovered human pathogen isolated from blood cultures of patients with infective endocarditis. Its phylogenetic position, as well as those of its closely related species, remains inconclusive when single genes were used for phylogenetic analysis. For example, S. sinensis branched out from members of the anginosus, mitis, and sanguinis groups in the 16S ribosomal RNA gene phylogenetic tree, but it was clustered with members of the anginosus and sanguinis groups when groEL gene sequences used for analysis. In this study, we sequenced the draft genome of S. sinensis and used a polyphasic approach, including concatenated genes, whole genomes, and matrix-assisted laser desorption ionization-time of flight mass spectrometry to analyze the phylogeny of S. sinensis. The size of the S. sinensis draft genome is 2.06 Mb, with GC content of 42.2%. Phylogenetic analysis using 50 concatenated genes or whole genomes revealed that S. sinensis formed a distinct cluster with Streptococcus oligofermentans and Streptococcus cristatus, and these three streptococci were clustered with the “sanguinis group.” As for phylogenetic analysis using hierarchical cluster analysis of the mass spectra of streptococci, S. sinensis also formed a distinct cluster with S. oligofermentans and S. cristatus, but these three streptococci were clustered with the “mitis group.” On the basis of the findings, we propose a novel group, named “sinensis group,” to include S. sinensis, S. oligofermentans, and S. cristatus, in the Streptococcus genus. Our study also illustrates the power of phylogenomic analyses for resolving ambiguities in bacterial taxonomy. PMID:25331233

Clonality of Bacterial Pathogens Causing Hospital-Acquired Pneumonia.

PubMed

Pudová, V; Htoutou Sedláková, M; Kolář, M

2016-09-01

Hospital-acquired pneumonia (HAP) is one of the most serious complications in patients staying in intensive care units. This multicenter study of Czech patients with HAP aimed at assessing the clonality of bacterial pathogens causing the condition. Bacterial isolates were compared using pulsed-field gel electrophoresis. Included in this study were 330 patients hospitalized between May 1, 2013 and December 31, 2014 at departments of anesthesiology and intensive care medicine of four big hospitals in the Czech Republic. A total of 531 bacterial isolates were obtained, of which 267 were classified as etiological agents causing HAP. Similarity or identity was assessed in 231 bacterial isolates most frequently obtained from HAP patients. Over the study period, no significant clonal spread was noted. Most isolates were unique strains, and the included HAP cases may therefore be characterized as mostly endogenous. Yet there were differences in species and potential identical isolates between the participating centers. In three hospitals, Gram-negative bacteria (Enterobacteriaceae and Pseudomonas aeruginosa) prevailed as etiological agents, and Staphylococcus aureus was most prevalent in the fourth center.

[Streptococcus pyogenes--much more than the aetiological agent of scarlet fever].

PubMed

Stock, Ingo

2009-11-01

The grampositive bacterium S. pyogenes (beta-haemolytic group A Streptococcus) is a natural colonizer of the human oropharynx mucous membrane and one of the most common agents of infectious diseases in humans. S. pyogenes causes the widest range of disease in humans among all bacterial pathogens. It is responsible for various skin infections such as impetigo contagiosa and erysipelas, and localized mucous membrane infections of the oropharynx (e. g. tonsillitis and pharyngitis). Betahaemolytic group A Streptococcus causes also invasive diseases such as sepses including puerperal sepsis. Additionally, S. pyogenes induces toxin-mediated syndromes, i. e. scarlet fever, streptococcal toxic shock syndrome (STSS) and necrotizing fasciitis (NF). STSS and NF are severe, frequently fatal diseases that have emerged in Europe and Northern America during the last two decades. Finally, some immunpathological diseases such as acute rheumatic fever and glomerulonephritis also result from S. pyogenes infections. Most scientists recommend penicillins (benzylpenicillin, phenoxymethylpenicllin) as drugs of first choice for treatment of Streptococcus tonsillopharyngitis and scarlet fever. Erysipelas and some other skin infections should be treated with benzylpenicillin. Intensive care measurements are needed for treatment of severe toxin-mediated S. pyogenes diseases. These measurements include the elimination of internal bacterial foci, concomitant application of clindamycin and benzylpenicillin and suitable treatment of shock symptoms. Management of immunpathological diseases requires antiphlogistical therapy. Because of the wide distribution of S. pyogenes in the general population and the lack of an effective vaccine, possibilities for prevention allowing a suitable protection for diseases due to S. pyogenes are very limited.

Acute bacterial meningitis in Iran: Systematic review and meta-analysis

PubMed Central

Riahi, Seyed Mohammad; Nasiri, Mohammad Javad; Fallah, Fatemeh; Dabiri, Hossein; Pouriran, Ramin

2017-01-01

Introduction Bacterial meningitis persists in being a substantial cause of high mortality and severe neurological morbidity, despite the advances in antimicrobial therapy. Accurate data has not been available regarding the epidemiology of bacterial meningitis particularly in developing countries, yet. Indeed, the present systematic review provides a comprehensive data analysis on the prevalence and epidemiology of bacterial meningitis in Iran. Methods We systematically reviewed articles from 1994 to 2015. The reports which contained the prevalence and etiology of acute bacterial meningitis by valid clinical and laboratory diagnosis were comprised in the present study. Results Our analysis indicated that Streptococcus pneumoniae (30% [I2 = 56% p < 0.01]), Haemophilus influenza type b (15% [I2 = 82.75% p < 0.001]), coagulase negative staphylococci (CoNS) (14% [I2 = 60.5% p < 0.06]), and Neisseria meningitidis (13% [I2 = 74.16% p < 0.001]) were the most common cause of acute bacterial meningitis among meningitis cases in Iran. Notably, high frequency rates of nosocomial meningitis pathogens were detected in the present analysis. Conclusions It was magnificently attained that the majority of cases for bacterial meningitis in Iran could be avertable by public immunization schemes and by preventive care to inhibit the broadening of hospital acquired pathogens. PMID:28170400

Acute bacterial meningitis in Iran: Systematic review and meta-analysis.

PubMed

Houri, Hamidreza; Pormohammad, Ali; Riahi, Seyed Mohammad; Nasiri, Mohammad Javad; Fallah, Fatemeh; Dabiri, Hossein; Pouriran, Ramin

2017-01-01

Bacterial meningitis persists in being a substantial cause of high mortality and severe neurological morbidity, despite the advances in antimicrobial therapy. Accurate data has not been available regarding the epidemiology of bacterial meningitis particularly in developing countries, yet. Indeed, the present systematic review provides a comprehensive data analysis on the prevalence and epidemiology of bacterial meningitis in Iran. We systematically reviewed articles from 1994 to 2015. The reports which contained the prevalence and etiology of acute bacterial meningitis by valid clinical and laboratory diagnosis were comprised in the present study. Our analysis indicated that Streptococcus pneumoniae (30% [I2 = 56% p < 0.01]), Haemophilus influenza type b (15% [I2 = 82.75% p < 0.001]), coagulase negative staphylococci (CoNS) (14% [I2 = 60.5% p < 0.06]), and Neisseria meningitidis (13% [I2 = 74.16% p < 0.001]) were the most common cause of acute bacterial meningitis among meningitis cases in Iran. Notably, high frequency rates of nosocomial meningitis pathogens were detected in the present analysis. It was magnificently attained that the majority of cases for bacterial meningitis in Iran could be avertable by public immunization schemes and by preventive care to inhibit the broadening of hospital acquired pathogens.

Ecology and pathogenicity of gastrointestinal Streptococcus bovis.

PubMed

Herrera, Paul; Kwon, Young Min; Ricke, Steven C

2009-01-01

Streptococcus bovis is an indigenous resident in the gastrointestinal tracts of both humans and animals. S. bovis is one of the major causes of bacterial endocarditis and has been implicated in the incidence of human colon cancer, possibly due to chronic inflammatory response at the site of intestinal colonization. Certain feeding regimens in ruminants can lead to overgrowth of S. bovis in the rumen, resulting in the over-production of lactate and capsular polysaccharide causing acute ruminal acidosis and bloat, respectively. There are multiple strategies in controlling acute lactic acidosis and bloat. The incidence of the two diseases may be controlled by strict dietary management. Gradual introduction of grain-based diets and the feeding of coarsely chopped roughage decrease the incidence of the two disease entities. Ionophores, which have been used to enhance feed conversion and growth rate in cattle, have been shown to inhibit the growth of lactic acid bacteria in the rumen. Other methods of controlling lactic acid bacteria in the ruminal environment (dietary supplementation of long-chain fatty acids, induction of passive and active immune responses to the bacteria, and the use of lytic bacteriophages) have also been investigated. It is anticipated that through continued in-depth ecological analysis of S. bovis the characteristics responsible for human and animal pathogenesis would be sufficiently identified to a point where more effective control strategies for the control of this bacteria can be developed.

Mixed Streptococcus pneumoniae and Streptococcus pyogenes meningitis in an immunocompromised adult patient: a case report.

PubMed

Demerle, Clémence; Ivanov, Vadim; Mercier, Cédric; Costello, Régis; Drancourt, Michel

2015-11-29

Community-acquired meningitis is a monomicrobial infection caused by either viruses or bacteria in the vast majority of patients. We report here one exceptional case of a patient with mixed bacterial meningitis due to Streptococcus pneumoniae and Streptococcus pyogenes. We report the case of a 68-year-old immunocompromised Caucasian man suffering from otitis and then meningitis caused by Streptococcus pneumoniae and Streptococcus pyogenes. Bacteria were undistinguishable by direct microscopic examination of the cerebrospinal fluid. He responded well to treatment with cefotaxime and dexamethasone, with no sequelae observed at the 4-month follow-up. This first reported case of mixed S. pneumoniae and S. pyogenes meningitis illustrates the life-threatening consequences of barotrauma in immunocompromised patients suffering from otorhinolaryngeal infections.

Vizantin inhibits bacterial adhesion without affecting bacterial growth and causes Streptococcus mutans biofilm to detach by altering its internal architecture.

PubMed

Takenaka, Shoji; Oda, Masataka; Domon, Hisanori; Ohsumi, Tatsuya; Suzuki, Yuki; Ohshima, Hayato; Yamamoto, Hirofumi; Terao, Yutaka; Noiri, Yuichiro

2016-11-11

An ideal antibiofilm strategy is to control both in the quality and quantity of biofilm while maintaining the benefits derived from resident microflora. Vizantin, a recently developed immunostimulating compound, has also been found to have antibiofilm property. This study evaluated the influence on biofilm formation of Streptococcus mutans in the presence of sulfated vizantin and biofilm development following bacterial adhesion on a hydroxyapatite disc coated with sulfated vizantin. Supplementation with sulfated vizantin up to 50 μM did not affect either bacterial growth or biofilm formation, whereas 50 μM sulfated vizantin caused the biofilm to readily detach from the surface. Sulfated vizantin at the concentration of 50 μM upregulated the expression of the gtfB and gtfC genes, but downregulated the expression of the gtfD gene, suggesting altered architecture in the biofilm. Biofilm development on the surface coated with sulfated vizantin was inhibited depending on the concentration, suggesting prevention from bacterial adhesion. Among eight genes related to bacterial adherence in S. mutans, expression of gtfB and gtfC was significantly upregulated, whereas the expression of gtfD, GbpA and GbpC was downregulated according to the concentration of vizantin, especially with 50 μM vizantin by 0.8-, 0.4-, and 0.4-fold, respectively. These findings suggest that sulfated vizantin may cause structural degradation as a result of changing gene regulation related to bacterial adhesion and glucan production of S. mutans. Copyright © 2016 Elsevier Inc. All rights reserved.

Viable bacterial population and persistence of foodborne pathogens on the pear carpoplane.

PubMed

Duvenage, Francois J; Duvenage, Stacey; Du Plessis, Erika M; Volschenk, Quinton; Korsten, Lise

2017-03-01

Knowledge on the culturable bacteria and foodborne pathogen presence on pears is important for understanding the impact of postharvest practices on food safety assurance. Pear fruit bacteria were investigated from the point of harvest, following chlorine drenching and after controlled atmosphere (CA) storage to assess the impact on natural bacterial populations and potential foodborne pathogens. Salmonella spp. and Listeria monocytogenes were detected on freshly harvested fruit in season one. During season one, chemical drenching and CA storage did not have a significant effect on the bacterial load of orchard pears, except for two farms where the populations were lower 'after CA storage'. During season two, bacterial populations of orchard pears from three of the four farms increased significantly following drenching; however, the bacterial load decreased 'after CA storage'. Bacteria isolated following enumeration included Enterobacteriaceae, Microbacteriaceae, Pseudomonadaceae and Bacillaceae, with richness decreasing 'after drench' and 'after CA storage'. Salmonella spp. and L. monocytogenes were not detected after postharvest practices. Postharvest practices resulted in decreased bacterial species richness. Understanding how postharvest practices have an impact on the viable bacterial populations of pear fruit will contribute to the development of crop-specific management systems for food safety assurance. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

Detection of Viral and Bacterial Pathogens in Hospitalized Children With Acute Respiratory Illnesses, Chongqing, 2009–2013

PubMed Central

Wei, Lan; Liu, Wei; Zhang, Xiao-Ai; Liu, En-Mei; Wo, Yin; Cowling, Benjamin J.; Cao, Wu-Chun

2015-01-01

Abstract Acute respiratory infections (ARIs) cause large disease burden each year. The codetection of viral and bacterial pathogens is quite common; however, the significance for clinical severity remains controversial. We aimed to identify viruses and bacteria in hospitalized children with ARI and the impact of mixed detections. Hospitalized children with ARI aged ≤16 were recruited from 2009 to 2013 at the Children's Hospital of Chongqing Medical University, Chongqing, China. Nasopharyngeal aspirates (NPAs) were collected for detection of common respiratory viruses by reverse transcription polymerase chain reaction (RT-PCR) or PCR. Bacteria were isolated from NPAs by routine culture methods. Detection and codetection frequencies and clinical features and severity were compared. Of the 3181 hospitalized children, 2375 (74.7%) were detected with ≥1 virus and 707 (22.2%) with ≥1 bacteria, 901 (28.3%) with ≥2 viruses, 57 (1.8%) with ≥2 bacteria, and 542 (17.0%) with both virus and bacteria. The most frequently detected were Streptococcus pneumoniae, respiratory syncytial virus, parainfluenza virus, and influenza virus. Clinical characteristics were similar among different pathogen infections for older group (≥6 years old), with some significant difference for the younger. Cases with any codetection were more likely to present with fever; those with ≥2 virus detections had higher prevalence of cough; cases with virus and bacteria codetection were more likely to have cough and sputum. No significant difference in the risk of pneumonia, severe pneumonia, and intensive care unit admission were found for any codetection than monodetection. There was a high codetection rate of common respiratory pathogens among hospitalized pediatric ARI cases, with fever as a significant predictor. Cases with codetection showed no significant difference in severity than those with single pathogens. PMID:25906103

In-vitro effect of edta-tris-lysozyme solutions on selected pathogenic bacteria.

PubMed

Wooley, R E; Blue, J L

1975-02-01

The in-vitro effect of EDTA-Tris-lysozyme solution on 16 pathogenic bacteria of medical or veterinary importance was determined. Marked decreases in bacterial count occurred with Pseudomonas aeruginosa, Escherichia coli, Moraxella osloensis and Campylobacter fetus, and smaller decreses with Salmonella typhimurium, Shigella boydii, Aeromonas hydrophila, proteus mirabilis, Listeria monocytogenes and Erysipelothrix insidiosa. The test solution had no effect on Klebsiella ozaenae, Brucella canis, Cornynebacterium pyogenes, Coryne, renale, Streptococcus equi and staphylococcus aureus.

Development of Rare Bacterial Monosaccharide Analogs for Metabolic Glycan Labeling in Pathogenic Bacteria.

PubMed

Clark, Emily L; Emmadi, Madhu; Krupp, Katharine L; Podilapu, Ananda R; Helble, Jennifer D; Kulkarni, Suvarn S; Dube, Danielle H

2016-12-16

Bacterial glycans contain rare, exclusively bacterial monosaccharides that are frequently linked to pathogenesis and essentially absent from human cells. Therefore, bacterial glycans are intriguing molecular targets. However, systematic discovery of bacterial glycoproteins is hampered by the presence of rare deoxy amino sugars, which are refractory to traditional glycan-binding reagents. Thus, the development of chemical tools that label bacterial glycans is a crucial step toward discovering and targeting these biomolecules. Here, we explore the extent to which metabolic glycan labeling facilitates the studying and targeting of glycoproteins in a range of pathogenic and symbiotic bacterial strains. We began with an azide-containing analog of the naturally abundant monosaccharide N-acetylglucosamine and discovered that it is not broadly incorporated into bacterial glycans, thus revealing a need for additional azidosugar substrates to broaden the utility of metabolic glycan labeling in bacteria. Therefore, we designed and synthesized analogs of the rare deoxy amino d-sugars N-acetylfucosamine, bacillosamine, and 2,4-diacetamido-2,4,6-trideoxygalactose and established that these analogs are differentially incorporated into glycan-containing structures in a range of pathogenic and symbiotic bacterial species. Further application of these analogs will refine our knowledge of the glycan repertoire in diverse bacteria and may find utility in treating a variety of infectious diseases with selectivity.

Fueling the caries process: carbohydrate metabolism and gene regulation by Streptococcus mutans

PubMed Central

Moye, Zachary D.; Zeng, Lin; Burne, Robert A.

2014-01-01

The nature of the oral cavity and host behaviors has mandated that the oral microbiota evolve mechanisms for coping with environmental fluctuations, especially changes in the type and availability of carbohydrates. In the case of human dental caries, the presence of excess carbohydrates is often responsible for altering the local environment to be more favorable for species associated with the initiation and progression of disease, including Streptococcus mutans. Some of the earliest endeavors to understand how cariogenic species respond to environmental perturbations were carried out using chemostat cultivation, which provides fine control over culture conditions and bacterial behaviors. The development of genome-scale methodologies has allowed for the combination of sophisticated cultivation technologies with genome-level analysis to more thoroughly probe how bacterial pathogens respond to environmental stimuli. Recent investigations in S. mutans and other closely related streptococci have begun to reveal that carbohydrate metabolism can drastically impact pathogenic potential and highlight the important influence that nutrient acquisition has on the success of pathogens; inside and outside of the oral cavity. Collectively, research into pathogenic streptococci, which have evolved in close association with the human host, has begun to unveil the essential nature of careful orchestration of carbohydrate acquisition and catabolism to allow the organisms to persist and, when conditions allow, initiate or worsen disease. PMID:25317251

Biological activities of Allium sativum and Zingiber officinale extracts on clinically important bacterial pathogens, their phytochemical and FT-IR spectroscopic analysis.

PubMed

Awan, Uzma Azeem; Ali, Shaukat; Shahnawaz, Amna Mir; Shafique, Irsa; Zafar, Atiya; Khan, Muhammad Abdul Rauf; Ghous, Tahseen; Saleem, Azhar; Andleeb, Saiqa

2017-05-01

The spread of bacterial infectious diseases is a major public threat. Herbs and spices have offered an excellent, important and useful source of antimicrobial agents against many pathological infections. In the current study, the antimicrobial potency of fresh, naturally and commercial dried Allium sativum and Zingiber officinale extracts had been investigated against seven local clinical bacterial isolates such as Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumonia, Staphylococcus aureus, Streptococcus pyogenes, Staphylococcus epidermidis, and Serratia marcesnces by the agar disc diffusion method. All tested pathogens except P. aeruginosa and E. coli were most susceptible to ethanolic and methanolic extracts of A. sativum. Similarly, chloroform and diethyl ether extracts of Z. officinale showed a greater zone of inhibition of tested pathogens except for P. aeruginosa and E. coli. We found that all extracts of A. sativum and Z. officinale have a strong antibacterial effect compared to recommended standard antibiotics through activity index. All results were evaluated statistically and a significant difference was recorded at P< 0.05. Antioxidant activity of extracts showed that 10 out of 13 extracts have high scavenging potential. Thin layer chromatography profiling of all extracts of A. sativum and Z. officinale proposed the presence of various phytochemicals such as tannins, phenols, alkaloids, steroids and saponins. Retention factor of diverse phytochemicals provides a valuable clue regarding their polarity and the selection of solvents for separation of phytochemicals. Significant inhibition of S. aureus was also observed through TLC-Bioautography. FT-IR Spectrometry was also performed to characterize both natural and commercial extracts of A. sativum and Z. officinale to evaluate bioactive compounds. These findings provide new insights to use A. sativum and Z. officinale as potential plant sources for controlling pathogenic bacteria and potentially

Dancing with the Stars: How Choreographed Bacterial Interactions Dictate Nososymbiocity and Give Rise to Keystone Pathogens, Accessory Pathogens, and Pathobionts.

PubMed

Hajishengallis, George; Lamont, Richard J

2016-06-01

Many diseases that originate on mucosal membranes ensue from the action of polymicrobial communities of indigenous organisms working in concert to disrupt homeostatic mechanisms. Multilevel physical and chemical communication systems among constituent organisms underlie polymicrobial synergy and dictate the community's pathogenic potential or nososymbiocity, that is, disease arising from living together with a susceptible host. Functional specialization of community participants, often originating from metabolic codependence, has given rise to several newly appreciated designations within the commensal-to-pathogen spectrum. Accessory pathogens, while inherently commensal in a particular microenvironment, nonetheless enhance the colonization or metabolic activity of pathogens. Keystone pathogens (bacterial drivers or alpha-bugs) exert their influence at low abundance by modulating both the composition and levels of community participants and by manipulating host responses. Pathobionts (or bacterial passengers) exploit disrupted host homeostasis to flourish and promote inflammatory disease. In this review we discuss how commensal or pathogenic properties of organisms are not intrinsic features, and have to be considered within the context of both the microbial community in which they reside and the host immune status. Copyright © 2016 Elsevier Ltd. All rights reserved.

A Rab-centric perspective of bacterial pathogen-occupied vacuoles.

PubMed

Sherwood, Racquel Kim; Roy, Craig R

2013-09-11

The ability to create and maintain a specialized organelle that supports bacterial replication is an important virulence property for many intracellular pathogens. Living in a membrane-bound vacuole presents inherent challenges, including the need to remodel a plasma membrane-derived organelle into a novel structure that will expand and provide essential nutrients to support replication, while also having the vacuole avoid membrane transport pathways that target bacteria for destruction in lysosomes. It is clear that pathogenic bacteria use different strategies to accomplish these tasks. The dynamics by which host Rab GTPases associate with pathogen-occupied vacuoles provide insight into the mechanisms used by different bacteria to manipulate host membrane transport. In this review we highlight some of the strategies bacteria use to maintain a pathogen-occupied vacuole by focusing on the Rab proteins involved in biogenesis and maintenance of these novel organelles. Copyright © 2013 Elsevier Inc. All rights reserved.

Frequency and levels of candidate endodontic pathogens in acute apical abscesses as compared to asymptomatic apical periodontitis.

PubMed

Rôças, Isabela N; Siqueira, José F

2018-01-01

Acute apical abscess is caused by bacteria that leave the infected dental root canal to invade the periodontal tissues. Most species occurring in abscesses are also found in asymptomatic infections; therefore, the possibility exists that not only the presence of certain species but also their specific counts influence the appearance of symptoms. This molecular study compared the frequency and levels of several candidate endodontic pathogens in teeth with acute apical abscesses and asymptomatic apical periodontitis. Samples were taken from the root canals of teeth with asymptomatic apical periodontitis (n = 73) and by aspiration of purulent exudate from acute abscesses (n = 55). DNA was extracted from samples and bacterial identifications were performed by a closed-ended semi-quantitative reverse-capture checkerboard approach targeting 40 bacterial species/phylotypes. Bacterial DNA was detected in all cases. In abscesses, the most prevalent taxa were Fusobacterium nucleatum (60%), Porphyromonas endodontalis (53%), Parvimonas micra (51%), and Streptococcus species (45%). The most frequently detected taxa in asymptomatic teeth were P. endodontalis (63%), Dialister invisus (58%), Olsenella uli (56%), and F. nucleatum (51%). None of the targeted taxa were significantly associated with abscesses when only mere presence was evaluated (p>0.05). However, semi-quantitative data demonstrated that P. endodontalis, Prevotella baroniae, Treponema denticola and Streptococcus species were significantly more frequent at levels >105 in abscesses than in asymptomatic cases (p<0.05). None of the target species/phylotypes were associated with abscesses in terms of frequency. However, some taxa were significantly found in higher levels in abscesses. Presence of a potentially virulent pathogen in high counts may increase the collective pathogenicity of the bacterial community and give rise to symptoms.

Frequency and levels of candidate endodontic pathogens in acute apical abscesses as compared to asymptomatic apical periodontitis

PubMed Central

Rôças, Isabela N.

2018-01-01

Introduction Acute apical abscess is caused by bacteria that leave the infected dental root canal to invade the periodontal tissues. Most species occurring in abscesses are also found in asymptomatic infections; therefore, the possibility exists that not only the presence of certain species but also their specific counts influence the appearance of symptoms. This molecular study compared the frequency and levels of several candidate endodontic pathogens in teeth with acute apical abscesses and asymptomatic apical periodontitis. Methods Samples were taken from the root canals of teeth with asymptomatic apical periodontitis (n = 73) and by aspiration of purulent exudate from acute abscesses (n = 55). DNA was extracted from samples and bacterial identifications were performed by a closed-ended semi-quantitative reverse-capture checkerboard approach targeting 40 bacterial species/phylotypes. Results Bacterial DNA was detected in all cases. In abscesses, the most prevalent taxa were Fusobacterium nucleatum (60%), Porphyromonas endodontalis (53%), Parvimonas micra (51%), and Streptococcus species (45%). The most frequently detected taxa in asymptomatic teeth were P. endodontalis (63%), Dialister invisus (58%), Olsenella uli (56%), and F. nucleatum (51%). None of the targeted taxa were significantly associated with abscesses when only mere presence was evaluated (p>0.05). However, semi-quantitative data demonstrated that P. endodontalis, Prevotella baroniae, Treponema denticola and Streptococcus species were significantly more frequent at levels >105 in abscesses than in asymptomatic cases (p<0.05). Conclusion None of the target species/phylotypes were associated with abscesses in terms of frequency. However, some taxa were significantly found in higher levels in abscesses. Presence of a potentially virulent pathogen in high counts may increase the collective pathogenicity of the bacterial community and give rise to symptoms. PMID:29293651

Capsular Sialic Acid of Streptococcus suis Serotype 2 Binds to Swine Influenza Virus and Enhances Bacterial Interactions with Virus-Infected Tracheal Epithelial Cells

PubMed Central

Wang, Yingchao; Gagnon, Carl A.; Savard, Christian; Music, Nedzad; Srednik, Mariela; Segura, Mariela; Lachance, Claude; Bellehumeur, Christian

2013-01-01

Streptococcus suis serotype 2 is an important swine bacterial pathogen, and it is also an emerging zoonotic agent. It is unknown how S. suis virulent strains, which are usually found in low quantities in pig tonsils, manage to cross the first host defense lines to initiate systemic disease. Influenza virus produces a contagious infection in pigs which is frequently complicated by bacterial coinfections, leading to significant economic impacts. In this study, the effect of a preceding swine influenza H1N1 virus (swH1N1) infection of swine tracheal epithelial cells (NTPr) on the ability of S. suis serotype 2 to adhere to, invade, and activate these cells was evaluated. Cells preinfected with swH1N1 showed bacterial adhesion and invasion levels that were increased more than 100-fold compared to those of normal cells. Inhibition studies confirmed that the capsular sialic acid moiety is responsible for the binding to virus-infected cell surfaces. Also, preincubation of S. suis with swH1N1 significantly increased bacterial adhesion to/invasion of epithelial cells, suggesting that S. suis also uses swH1N1 as a vehicle to invade epithelial cells when the two infections occur simultaneously. Influenza virus infection may facilitate the transient passage of S. suis at the respiratory tract to reach the bloodstream and cause bacteremia and septicemia. S. suis may also increase the local inflammation at the respiratory tract during influenza infection, as suggested by an exacerbated expression of proinflammatory mediators in coinfected cells. These results give new insight into the complex interactions between influenza virus and S. suis in a coinfection model. PMID:24082069

Hemocytes from Pediculus humanus humanus are hosts for human bacterial pathogens

PubMed Central

Coulaud, Pierre-Julien; Lepolard, Catherine; Bechah, Yassina; Berenger, Jean-Michel; Raoult, Didier; Ghigo, Eric

2015-01-01

Pediculus humanus humanus is an human ectoparasite which represents a serious public health threat because it is vector for pathogenic bacteria. It is important to understand and identify where bacteria reside in human body lice to define new strategies to counterstroke the capacity of vectorization of the bacterial pathogens by body lice. It is known that phagocytes from vertebrates can be hosts or reservoirs for several microbes. Therefore, we wondered if Pediculus humanus humanus phagocytes could hide pathogens. In this study, we characterized the phagocytes from Pediculus humanus humanus and evaluated their contribution as hosts for human pathogens such as Rickettsia prowazekii, Bartonella Quintana, and Acinetobacter baumannii. PMID:25688336

Bacterial Serine/Threonine Protein Kinases in Host-Pathogen Interactions*

PubMed Central

Canova, Marc J.; Molle, Virginie

2014-01-01

In bacterial pathogenesis, monitoring and adapting to the dynamically changing environment in the host and an ability to disrupt host immune responses are critical. The virulence determinants of pathogenic bacteria include the sensor/signaling proteins of the serine/threonine protein kinase (STPK) family that have a dual role of sensing the environment and subverting specific host defense processes. STPKs can sense a wide range of signals and coordinate multiple cellular processes to mount an appropriate response. Here, we review some of the well studied bacterial STPKs that are essential virulence factors and that modify global host responses during infection. PMID:24554701

Bacterial serine/threonine protein kinases in host-pathogen interactions.

PubMed

Canova, Marc J; Molle, Virginie

2014-04-04

In bacterial pathogenesis, monitoring and adapting to the dynamically changing environment in the host and an ability to disrupt host immune responses are critical. The virulence determinants of pathogenic bacteria include the sensor/signaling proteins of the serine/threonine protein kinase (STPK) family that have a dual role of sensing the environment and subverting specific host defense processes. STPKs can sense a wide range of signals and coordinate multiple cellular processes to mount an appropriate response. Here, we review some of the well studied bacterial STPKs that are essential virulence factors and that modify global host responses during infection.

From the microbiome to the central nervous system, an update on the epidemiology and pathogenesis of bacterial meningitis in childhood

PubMed Central

Janowski, Andrew B; Newland, Jason G

2017-01-01

In the past century, advances in antibiotics and vaccination have dramatically altered the incidence and clinical outcomes of bacterial meningitis. We review the shifting epidemiology of meningitis in children, including after the implementation of vaccines that target common meningitic pathogens and the introduction of intrapartum antibiotic prophylaxis offered to mothers colonized with Streptococcus agalactiae. We also discuss what is currently known about the pathogenesis of meningitis. Recent studies of the human microbiome have illustrated dynamic relationships of bacterial and viral populations with the host, which may potentiate the risk of bacterial meningitis. PMID:28184287

Bacteriophages for detection and control of bacterial pathogens in food and food-processing environment.

PubMed

Brovko, Lubov Y; Anany, Hany; Griffiths, Mansel W

2012-01-01

This chapter presents recent advances in bacteriophage research and their application in the area of food safety. Section 1 describes general facts on phage biology that are relevant to their application for control and detection of bacterial pathogens in food and environmental samples. Section 2 summarizes the recently acquired data on application of bacteriophages to control growth of bacterial pathogens and spoilage organisms in food and food-processing environment. Section 3 deals with application of bacteriophages for detection and identification of bacterial pathogens. Advantages of bacteriophage-based methods are presented and their shortcomings are discussed. The chapter is intended for food scientist and food product developers, and people in food inspection and health agencies with the ultimate goal to attract their attention to the new developing technology that has a tremendous potential in providing means for producing wholesome and safe food. Copyright © 2012 Elsevier Inc. All rights reserved.

A historical overview of bacteriophage therapy as an alternative to antibiotics for the treatment of bacterial pathogens

PubMed Central

Wittebole, Xavier; De Roock, Sophie; Opal, Steven M

2014-01-01

The seemingly inexorable spread of antibiotic resistance genes among microbial pathogens now threatens the long-term viability of our current antimicrobial therapy to treat severe bacterial infections such as sepsis. Antibiotic resistance is reaching a crisis situation in some bacterial pathogens where few therapeutic alternatives remain and pan-resistant strains are becoming more prevalent. Non-antibiotic therapies to treat bacterial infections are now under serious consideration and one possible option is the therapeutic use of specific phage particles that target bacterial pathogens. Bacteriophage therapy has essentially been re-discovered by modern medicine after widespread use of phage therapy in the pre-antibiotic era lost favor, at least in Western countries, after the introduction of antibiotics. We review the current therapeutic rationale and clinical experience with phage therapy as a treatment for invasive bacterial infection as novel alternative to antimicrobial chemotherapy. PMID:23973944

Host-Directed Antimicrobial Drugs with Broad-Spectrum Efficacy against Intracellular Bacterial Pathogens

PubMed Central

Czyż, Daniel M.; Potluri, Lakshmi-Prasad; Jain-Gupta, Neeta; Riley, Sean P.; Martinez, Juan J.; Steck, Theodore L.; Crosson, Sean; Gabay, Joëlle E.

2014-01-01

ABSTRACT We sought a new approach to treating infections by intracellular bacteria, namely, by altering host cell functions that support their growth. We screened a library of 640 Food and Drug Administration (FDA)-approved compounds for agents that render THP-1 cells resistant to infection by four intracellular pathogens. We identified numerous drugs that are not antibiotics but were highly effective in inhibiting intracellular bacterial growth with limited toxicity to host cells. These compounds are likely to target three kinds of host functions: (i) G protein-coupled receptors, (ii) intracellular calcium signals, and (iii) membrane cholesterol distribution. The compounds that targeted G protein receptor signaling and calcium fluxes broadly inhibited Coxiella burnetii, Legionella pneumophila, Brucella abortus, and Rickettsia conorii, while those directed against cholesterol traffic strongly attenuated the intracellular growth of C. burnetii and L. pneumophila. These pathways probably support intracellular pathogen growth so that drugs that perturb them may be therapeutic candidates. Combining host- and pathogen-directed treatments is a strategy to decrease the emergence of drug-resistant intracellular bacterial pathogens. PMID:25073644

Bithionol blocks pathogenicity of bacterial toxins, ricin, and Zika virus

USDA-ARS?s Scientific Manuscript database

Disease pathways form overlapping networks, and hub proteins represent attractive targets for broad-spectrum drugs. Using bacterial toxins as a proof of concept, we describe a new approach of discovering broad-spectrum therapies capable of inhibiting host proteins that mediate multiple pathogenic pa...

Human Milk Oligosaccharides Exhibit Antimicrobial and Antibiofilm Properties against Group B Streptococcus.

PubMed

Ackerman, Dorothy L; Doster, Ryan S; Weitkamp, Jörn-Hendrik; Aronoff, David M; Gaddy, Jennifer A; Townsend, Steven D

2017-08-11

Streptococcus agalactiae (Group B Streptococcus, GBS) is a Gram-positive bacterial pathogen that causes invasive infections in both children and adults. During pregnancy, GBS is a significant cause of infection of the fetal membranes (chorioamnionitis), which can lead to intra-amniotic infection, preterm birth, stillbirth, and neonatal sepsis. Recently, breastfeeding has been thought to represent a potential mode of GBS transmission from mother to newborn, which might increase the risk for late-onset sepsis. Little is known, however, about the molecular components of breast milk that may support or prevent GBS colonization. In this study, we examine how human milk oligosaccharides (HMOs) affect the pathogenesis of GBS. HMOs from discrete donor samples were isolated and profiled by matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS). Growth and biofilm assays show that HMOs from mothers of specific milk groups can modulate the growth and biofilm formation of GBS. High-resolution field-emission gun scanning electron microscopy (SEM) and confocal laser scanning microscopy confirmed the quantitative biofilm assays and demonstrated cell arrangement perturbations in bacterial cultures treated with specific oligosaccharides. These findings demonstrate that HMOs affect the growth and cell biology of GBS. Finally, this study provides the first example of HMOs functioning as antibiofilm agents against GBS.

Isolation and Pathogenicity of Streptococcus iniae in Cultured Red Hybrid Tilapia in Malaysia.

PubMed

Rahmatullah, M; Ariff, M; Kahieshesfandiari, M; Daud, H M; Zamri-Saad, M; Sabri, M Y; Amal, M N A; Ina-Salwany, M Y

2017-12-01

This study describes the isolation and pathogenicity of Streptococcus iniae in cultured red hybrid tilapia (Nile Tilapia Oreochromis niloticus × Mozambique Tilapia O. mossambicus) in Malaysia. The isolated gram-positive S. iniae appeared punctiform, transparently white, catalase and oxidase negative and produced complete β-hemolysis on blood agar, while a PCR assay resulted in the amplification of the 16 S rRNA gene and lactate oxidase encoded genes. The isolate was sensitive to tetracycline, vancomycin, and bacitracin but was resistant to streptomycin, ampicillin, penicillin, and erythromycin. Pathogenicity trials conducted in local red hybrid tilapia (mean ± SE = 20.00 ± 0.45 g) showed 90.0, 96.7, and 100.0% mortality within 14 d postinfection following intraperitoneal exposure to 10 4 , 10 6 , and 10 8 CFU/mL of the pathogen, respectively. The clinical signs included erratic swimming, lethargy, and inappetance at 6 h postinfection, while mortality was recorded at less than 24 h postinfection in all infected groups. The LD 50-336 h of S. iniae against the red hybrid tilapia was 10 2 CFU/mL. The post mortem examinations revealed congested livers, kidneys, and spleens of the infected fish. This is the first report of S. iniae experimental infection in cultured red hybrid tilapia in Malaysia. Received January 20, 2017; accepted July 16, 2017.

Immune subversion by chromatin manipulation: a 'new face' of host-bacterial pathogen interaction.

PubMed

Arbibe, Laurence

2008-08-01

Bacterial pathogens have evolved various strategies to avoid immune surveillance, depending of their in vivo'lifestyle'. The identification of few bacterial effectors capable to enter the nucleus and modifying chromatin structure in host raises the fascinating questions of how pathogens modulate chromatin structure and why. Chromatin is a dynamic structure that maintains the stability and accessibility of the host DNA genome to the transcription machinery. This review describes the various strategies used by pathogens to interface with host chromatin. In some cases, chromatin injury can be a strategy to take control of major cellular functions, such as the cell cycle. In other cases, manipulation of chromatin structure at specific genomic locations by modulating epigenetic information provides a way for the pathogen to impose its own transcriptional signature onto host cells. This emerging field should strongly influence our understanding of chromatin regulation at interphase nucleus and may provide invaluable openings to the control of immune gene expression in inflammatory and infectious diseases.

Chemical interference with iron transport systems to suppress bacterial growth of Streptococcus pneumoniae.

PubMed

Yang, Xiao-Yan; Sun, Bin; Zhang, Liang; Li, Nan; Han, Junlong; Zhang, Jing; Sun, Xuesong; He, Qing-Yu

2014-01-01

Iron is an essential nutrient for the growth of most bacteria. To obtain iron, bacteria have developed specific iron-transport systems located on the membrane surface to uptake iron and iron complexes such as ferrichrome. Interference with the iron-acquisition systems should be therefore an efficient strategy to suppress bacterial growth and infection. Based on the chemical similarity of iron and ruthenium, we used a Ru(II) complex R-825 to compete with ferrichrome for the ferrichrome-transport pathway in Streptococcus pneumoniae. R-825 inhibited the bacterial growth of S. pneumoniae and stimulated the expression of PiuA, the iron-binding protein in the ferrichrome-uptake system on the cell surface. R-825 treatment decreased the cellular content of iron, accompanying with the increase of Ru(II) level in the bacterium. When the piuA gene (SPD_0915) was deleted in the bacterium, the mutant strain became resistant to R-825 treatment, with decreased content of Ru(II). Addition of ferrichrome can rescue the bacterial growth that was suppressed by R-825. Fluorescence spectral quenching showed that R-825 can bind with PiuA in a similar pattern to the ferrichrome-PiuA interaction in vitro. These observations demonstrated that Ru(II) complex R-825 can compete with ferrichrome for the ferrichrome-transport system to enter S. pneumoniae, reduce the cellular iron supply, and thus suppress the bacterial growth. This finding suggests a novel antimicrobial approach by interfering with iron-uptake pathways, which is different from the mechanisms used by current antibiotics.

Kynetic resazurin assay (KRA) for bacterial quantification of foodborne pathogens

NASA Astrophysics Data System (ADS)

Arenas, Yaxal; Mandel, Arkady; Lilge, Lothar

2012-03-01

Fast detection of bacterial concentrations is important for the food industry and for healthcare. Early detection of infections and appropriate treatment is essential since, the delay of treatments for bacterial infections tends to be associated with higher mortality rates. In the food industry and in healthcare, standard procedures require the count of colony-forming units in order to quantify bacterial concentrations, however, this method is time consuming and reports require three days to be completed. An alternative is metabolic-colorimetric assays which provide time efficient in vitro bacterial concentrations. A colorimetric assay based on Resazurin was developed as a time kinetic assay (KRA) suitable for bacterial concentration measurements. An optimization was performed by finding excitation and emission wavelengths for fluorescent acquisition. A comparison of two non-related bacteria, foodborne pathogens Escherichia coli and Listeria monocytogenes, was performed in 96 well plates. A metabolic and clonogenic dependence was established for fluorescent kinetic signals.

Rapid Evolution of Virulence and Drug Resistance in the Emerging Zoonotic Pathogen Streptococcus suis

PubMed Central

Holden, Matthew T. G.; Hauser, Heidi; Sanders, Mandy; Ngo, Thi Hoa; Cherevach, Inna; Cronin, Ann; Goodhead, Ian; Mungall, Karen; Quail, Michael A.; Price, Claire; Rabbinowitsch, Ester; Sharp, Sarah; Croucher, Nicholas J.; Chieu, Tran Bich; Thi Hoang Mai, Nguyen; Diep, To Song; Chinh, Nguyen Tran; Kehoe, Michael; Leigh, James A.; Ward, Philip N.; Dowson, Christopher G.; Whatmore, Adrian M.; Chanter, Neil; Iversen, Pernille; Gottschalk, Marcelo; Slater, Josh D.; Smith, Hilde E.; Spratt, Brian G.; Xu, Jianguo; Ye, Changyun; Bentley, Stephen; Barrell, Barclay G.; Schultsz, Constance; Maskell, Duncan J.; Parkhill, Julian

2009-01-01

Background Streptococcus suis is a zoonotic pathogen that infects pigs and can occasionally cause serious infections in humans. S. suis infections occur sporadically in human Europe and North America, but a recent major outbreak has been described in China with high levels of mortality. The mechanisms of S. suis pathogenesis in humans and pigs are poorly understood. Methodology/Principal Findings The sequencing of whole genomes of S. suis isolates provides opportunities to investigate the genetic basis of infection. Here we describe whole genome sequences of three S. suis strains from the same lineage: one from European pigs, and two from human cases from China and Vietnam. Comparative genomic analysis was used to investigate the variability of these strains. S. suis is phylogenetically distinct from other Streptococcus species for which genome sequences are currently available. Accordingly, ∼40% of the ∼2 Mb genome is unique in comparison to other Streptococcus species. Finer genomic comparisons within the species showed a high level of sequence conservation; virtually all of the genome is common to the S. suis strains. The only exceptions are three ∼90 kb regions, present in the two isolates from humans, composed of integrative conjugative elements and transposons. Carried in these regions are coding sequences associated with drug resistance. In addition, small-scale sequence variation has generated pseudogenes in putative virulence and colonization factors. Conclusions/Significance The genomic inventories of genetically related S. suis strains, isolated from distinct hosts and diseases, exhibit high levels of conservation. However, the genomes provide evidence that horizontal gene transfer has contributed to the evolution of drug resistance. PMID:19603075

Rapid, portable, multiplexed detection of bacterial pathogens directly from clinical sample matrices

DOE PAGES

Phaneuf, Christopher R.; Mangadu, Betty Lou Bosano; Piccini, Matthew E.; ...

2016-09-23

Enteric and diarrheal diseases are a major cause of childhood illness and death in countries with developing economies. Each year, more than half of a million children under the age of five die from these diseases. We have developed a portable, microfluidic platform capable of simultaneous, multiplexed detection of several of the bacterial pathogens that cause these diseases. Furthermore, this platform can perform fast, sensitive immunoassays directly from relevant, complex clinical matrices such as stool without extensive sample cleanup or preparation. Using only 1 µL of sample per assay, we demonstrate simultaneous multiplexed detection of four bacterial pathogens implicated inmore » diarrheal and enteric diseases in less than 20 min.« less

Rapid, portable, multiplexed detection of bacterial pathogens directly from clinical sample matrices

DOE Office of Scientific and Technical Information (OSTI.GOV)

Phaneuf, Christopher R.; Mangadu, Betty Lou Bosano; Piccini, Matthew E.

Enteric and diarrheal diseases are a major cause of childhood illness and death in countries with developing economies. Each year, more than half of a million children under the age of five die from these diseases. We have developed a portable, microfluidic platform capable of simultaneous, multiplexed detection of several of the bacterial pathogens that cause these diseases. Furthermore, this platform can perform fast, sensitive immunoassays directly from relevant, complex clinical matrices such as stool without extensive sample cleanup or preparation. Using only 1 µL of sample per assay, we demonstrate simultaneous multiplexed detection of four bacterial pathogens implicated inmore » diarrheal and enteric diseases in less than 20 min.« less

Antibacterial activity and mechanism of berberine against Streptococcus agalactiae

PubMed Central

Peng, Lianci; Kang, Shuai; Yin, Zhongqiong; Jia, Renyong; Song, Xu; Li, Li; Li, Zhengwen; Zou, Yuanfeng; Liang, Xiaoxia; Li, Lixia; He, Changliang; Ye, Gang; Yin, Lizi; Shi, Fei; Lv, Cheng; Jing, Bo

2015-01-01

The antibacterial activity and mechanism of berberine against Streptococcus agalactiae were investigated in this study by analyzing the growth, morphology and protein of the S. agalactiae cells treated with berberine. The antibacterial susceptibility test result indicated minimum inhibition concentration (MIC) of berberine against Streptococcus agalactiae was 78 μg/mL and the time-kill curves showed the correlation of concentration-time. After the bacteria was exposed to 78 μg/mL berberine, the fragmentary cell membrane and cells unequal division were observed by the transmission electron microscopy (TEM), indicating the bacterial cells were severely damaged. Sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) study demonstrated that berberine could damage bacterial cells through destroying cellular proteins. Meanwhile, Fluorescence microscope revealed that berberine could affect the synthesis of DNA. In conclusion, these results strongly suggested that berberine may damage the structure of bacterial cell membrane and inhibit synthesis of protein and DNA, which cause Streptococcus agalactiae bacteria to die eventually. PMID:26191220

Antibacterial activity and mechanism of berberine against Streptococcus agalactiae.

PubMed

Peng, Lianci; Kang, Shuai; Yin, Zhongqiong; Jia, Renyong; Song, Xu; Li, Li; Li, Zhengwen; Zou, Yuanfeng; Liang, Xiaoxia; Li, Lixia; He, Changliang; Ye, Gang; Yin, Lizi; Shi, Fei; Lv, Cheng; Jing, Bo

2015-01-01

The antibacterial activity and mechanism of berberine against Streptococcus agalactiae were investigated in this study by analyzing the growth, morphology and protein of the S. agalactiae cells treated with berberine. The antibacterial susceptibility test result indicated minimum inhibition concentration (MIC) of berberine against Streptococcus agalactiae was 78 μg/mL and the time-kill curves showed the correlation of concentration-time. After the bacteria was exposed to 78 μg/mL berberine, the fragmentary cell membrane and cells unequal division were observed by the transmission electron microscopy (TEM), indicating the bacterial cells were severely damaged. Sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) study demonstrated that berberine could damage bacterial cells through destroying cellular proteins. Meanwhile, Fluorescence microscope revealed that berberine could affect the synthesis of DNA. In conclusion, these results strongly suggested that berberine may damage the structure of bacterial cell membrane and inhibit synthesis of protein and DNA, which cause Streptococcus agalactiae bacteria to die eventually.

Cis-encoded non-coding antisense RNAs in streptococci and other low GC Gram (+) bacterial pathogens

PubMed Central

Cho, Kyu Hong; Kim, Jeong-Ho

2015-01-01

Due to recent advances of bioinformatics and high throughput sequencing technology, discovery of regulatory non-coding RNAs in bacteria has been increased to a great extent. Based on this bandwagon, many studies searching for trans-acting small non-coding RNAs in streptococci have been performed intensively, especially in the important human pathogen, group A and B streptococci. However, studies for cis-encoded non-coding antisense RNAs in streptococci have been scarce. A recent study shows antisense RNAs are involved in virulence gene regulation in group B streptococcus, S. agalactiae. This suggests antisense RNAs could have important roles in the pathogenesis of streptococcal pathogens. In this review, we describe recent discoveries of chromosomal cis-encoded antisense RNAs in streptococcal pathogens and other low GC Gram (+) bacteria to provide a guide for future studies. PMID:25859258

Fluorescence spectroscopy for rapid detection and classification of bacterial pathogens.

PubMed

Sohn, Miryeong; Himmelsbach, David S; Barton, Franklin E; Fedorka-Cray, Paula J

2009-11-01

This study deals with the rapid detection and differentiation of Escherichia coli, Salmonella, and Campylobacter, which are the most commonly identified commensal and pathogenic bacteria in foods, using fluorescence spectroscopy and multivariate analysis. Each bacterial sample cultured under controlled conditions was diluted in physiologic saline for analysis. Fluorescence spectra were collected over a range of 200-700 nm with 0.5 nm intervals on the PerkinElmer Fluorescence Spectrometer. The synchronous scan technique was employed to find the optimum excitation (lambda(ex)) and emission (lambda(em)) wavelengths for individual bacteria with the wavelength interval (Deltalambda) being varied from 10 to 200 nm. The synchronous spectra and two-dimensional plots showed two maximum lambda(ex) values at 225 nm and 280 nm and one maximum lambda(em) at 335-345 nm (lambda(em) = lambda(ex) + Deltalambda), which correspond to the lambda(ex) = 225 nm, Deltalambda = 110-120 nm, and lambda(ex) = 280 nm, Deltalambda = 60-65 nm. For all three bacterial genera, the same synchronous scan results were obtained. The emission spectra from the three bacteria groups were very similar, creating difficulty in classification. However, the application of principal component analysis (PCA) to the fluorescence spectra resulted in successful classification of the bacteria by their genus as well as determining their concentration. The detection limit was approximately 10(3)-10(4) cells/mL for each bacterial sample. These results demonstrated that fluorescence spectroscopy, when coupled with PCA processing, has the potential to detect and to classify bacterial pathogens in liquids. The methodology is rapid (>10 min), inexpensive, and requires minimal sample preparation compared to standard analytical methods for bacterial detection.

Phylogenomic and MALDI-TOF MS analysis of Streptococcus sinensis HKU4T reveals a distinct phylogenetic clade in the genus Streptococcus.

PubMed

Teng, Jade L L; Huang, Yi; Tse, Herman; Chen, Jonathan H K; Tang, Ying; Lau, Susanna K P; Woo, Patrick C Y

2014-10-20

Streptococcus sinensis is a recently discovered human pathogen isolated from blood cultures of patients with infective endocarditis. Its phylogenetic position, as well as those of its closely related species, remains inconclusive when single genes were used for phylogenetic analysis. For example, S. sinensis branched out from members of the anginosus, mitis, and sanguinis groups in the 16S ribosomal RNA gene phylogenetic tree, but it was clustered with members of the anginosus and sanguinis groups when groEL gene sequences used for analysis. In this study, we sequenced the draft genome of S. sinensis and used a polyphasic approach, including concatenated genes, whole genomes, and matrix-assisted laser desorption ionization-time of flight mass spectrometry to analyze the phylogeny of S. sinensis. The size of the S. sinensis draft genome is 2.06 Mb, with GC content of 42.2%. Phylogenetic analysis using 50 concatenated genes or whole genomes revealed that S. sinensis formed a distinct cluster with Streptococcus oligofermentans and Streptococcus cristatus, and these three streptococci were clustered with the "sanguinis group." As for phylogenetic analysis using hierarchical cluster analysis of the mass spectra of streptococci, S. sinensis also formed a distinct cluster with S. oligofermentans and S. cristatus, but these three streptococci were clustered with the "mitis group." On the basis of the findings, we propose a novel group, named "sinensis group," to include S. sinensis, S. oligofermentans, and S. cristatus, in the Streptococcus genus. Our study also illustrates the power of phylogenomic analyses for resolving ambiguities in bacterial taxonomy. © The Author(s) 2014. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

Prospective multi-centre sentinel surveillance for Haemophilus influenzae type b & other bacterial meningitis in Indian children

PubMed Central

Ramachandran, Padmanabhan; Fitzwater, Sean Patrick; Aneja, Satinder; Verghese, Valsan Philip; Kumar, Vishwajeet; Nedunchelian, Krishnamoorthy; Wadhwa, Nitya; Veeraraghavan, Balaji; Kumar, Rashmi; Meeran, Mohamed; Kapil, Arti; Jasmine, Sudha; Kumar, Aarti; Suresh, Saradha; Bhatnagar, Shinjini; Thomas, Kurien; Awasthi, Shally; Santosham, Mathuram; Chandran, Aruna

2013-01-01

Background & objectives: Haemophilus influenzae type b (Hib) is one of the leading bacterial causes of invasive disease in populations without access to Hib conjugate vaccines (Hib-CV). India has recently decided to introduce Hib-CV into the routine immunization programme in selected States. Longitudinal data quantifying the burden of bacterial meningitis and the proportion of disease caused by various bacteria are needed to track the impact of Hib-CV once introduced. A hospital-based sentinel surveillance network was established at four places in the country and this study reports the results of this ongoing surveillance. Methods: Children aged 1 to 23 months with suspected bacterial meningitis were enrolled in Chennai, Lucknow, New Delhi, and Vellore between July 2008 and June 2010. All cerebrospinal fluid (CSF) samples were tested using cytological, biochemical, and culture methods. Samples with abnormal CSF (≥10 WBC per μl) were tested by latex agglutination test for common paediatric bacterial meningitis pathogens. Results: A total of 708 patients with abnormal CSF were identified, 89 of whom had a bacterial pathogen confirmed. Hib accounted for the majority of bacteriologically confirmed cases, 62 (70%), while Streptococcus pneumoniae and group B Streptococcus were identified in 12 (13%) and seven (8%) cases, respectively. The other eight cases were a mix of other bacteria. The proportion of abnormal CSF and probable bacterial meningitis that was caused by Hib was 74 and 58 per cent lower at Christian Medical College (CMC), Vellore, which had a 41 per cent coverage of Hib-CV among all suspected meningitis cases, compared to the combined average proportion at the other three centres where a coverage between 1 and 8 per cent was seen (P<0.001 and P= 0.05, respectively). Interpretation & conclusions: Hib was found to be the predominant cause of bacterial meningitis in young children in diverse geographic locations in India. Possible indications of herd

Quantifying school officials' exposure to bacterial pathogens at graduation ceremonies using repeated observational measures.

PubMed

Bishai, David; Liu, Liang; Shiau, Stephanie; Wang, Harrison; Tsai, Cindy; Liao, Margaret; Prakash, Shivaani; Howard, Tracy

2011-06-01

The purpose of this study was to estimate the risk of acquiring pathogenic bacteria as a result of shaking hands at graduation ceremonies. School officials participating in graduation ceremonies at elementary, secondary, and postsecondary schools were recruited. Specimens were collected before and immediately following graduation. Cultures identified any pathogenic bacteria in each specimen. Subjects shook a total of 5,209 hands. Staphylococcus aureus was separately detected on one pregraduation right hand, one postgraduation right hand, and one postgraduation left hand. Nonpathogenic bacteria were collected in 93% of specimens. Pregraduation and postgraduation specimens were of different strains. We measured a risk of one new bacterial acquisition in a sample exposed to 5,209 handshakes yielding an overall estimate of 0.019 pathogens acquired per handshake. We conclude that a single handshake at a graduation offers only a small risk of bacterial pathogen acquisition.

Importance of Soil Amendments: Survival of Bacterial Pathogens in Manure and Compost Used as Organic Fertilizers.

PubMed

Sharma, Manan; Reynnells, Russell

2016-08-01

Biological soil amendments (BSAs) such as manure and compost are frequently used as organic fertilizers to improve the physical and chemical properties of soils. However, BSAs have been known to be a reservoir for enteric bacterial pathogens such as enterohemorrhagic Escherichia coli (EHEC), Salmonella spp., and Listeria spp. There are numerous mechanisms by which manure may transfer pathogens to growing fruits and vegetables, and several outbreaks of infections have been linked to manure-related contamination of leafy greens. In the United States several commodity-specific guidelines and current and proposed federal rules exist to provide guidance on the application of BSAs as fertilizers to soils, some of which require an interval between the application of manure to soils and the harvest of fruits and vegetables. This review examines the survival, persistence, and regrowth/resuscitation of bacterial pathogens in manure, biosolids, and composts. Moisture, along with climate and the physicochemical properties of soil, manure, or compost, plays a significant role in the ability of pathogens to persist and resuscitate in amended soils. Adaptation of enteric bacterial pathogens to the nonhost environment of soils may also extend their persistence in manure- or compost-amended soils. The presence of antibiotic-resistance genes in soils may also be increased by manure application. Overall, BSAs applied as fertilizers to soils can support the survival and regrowth of pathogens. BSAs should be handled and applied in a manner that reduces the prevalence of pathogens in soils and the likelihood of transfer of food-borne pathogens to fruits and vegetables. This review will focus on two BSAs-raw manure and composted manure (and other feedstocks)-and predominantly on the survival of enteric bacterial pathogens in BSAs as applied to soils as organic fertilizers.

Intra- and inter-species interactions within biofilms of important foodborne bacterial pathogens

PubMed Central

Giaouris, Efstathios; Heir, Even; Desvaux, Mickaël; Hébraud, Michel; Møretrø, Trond; Langsrud, Solveig; Doulgeraki, Agapi; Nychas, George-John; Kačániová, Miroslava; Czaczyk, Katarzyna; Ölmez, Hülya; Simões, Manuel

2015-01-01

A community-based sessile life style is the normal mode of growth and survival for many bacterial species. Under such conditions, cell-to-cell interactions are inevitable and ultimately lead to the establishment of dense, complex and highly structured biofilm populations encapsulated in a self-produced extracellular matrix and capable of coordinated and collective behavior. Remarkably, in food processing environments, a variety of different bacteria may attach to surfaces, survive, grow, and form biofilms. Salmonella enterica, Listeria monocytogenes, Escherichia coli, and Staphylococcus aureus are important bacterial pathogens commonly implicated in outbreaks of foodborne diseases, while all are known to be able to create biofilms on both abiotic and biotic surfaces. Particularly challenging is the attempt to understand the complexity of inter-bacterial interactions that can be encountered in such unwanted consortia, such as competitive and cooperative ones, together with their impact on the final outcome of these communities (e.g., maturation, physiology, antimicrobial resistance, virulence, dispersal). In this review, up-to-date data on both the intra- and inter-species interactions encountered in biofilms of these pathogens are presented. A better understanding of these interactions, both at molecular and biophysical levels, could lead to novel intervention strategies for controlling pathogenic biofilm formation in food processing environments and thus improve food safety. PMID:26347727

Asymptomatic Carriage of Group A Streptococcus Is Associated with Elimination of Capsule Production

PubMed Central

Jewell, Brittany E.; Olsen, Randall J.; Shelburne, Samuel A.; Fittipaldi, Nahuel; Beres, Stephen B.; Musser, James M.

2014-01-01

Humans commonly carry pathogenic bacteria asymptomatically, but despite decades of study, the underlying molecular contributors remain poorly understood. Here, we show that a group A streptococcus carriage strain contains a frameshift mutation in the hasA gene resulting in loss of hyaluronic acid capsule biosynthesis. This mutation was repaired by allelic replacement, resulting in restoration of capsule production in the isogenic derivative strain. The “repaired” isogenic strain was significantly more virulent than the carriage strain in a mouse model of necrotizing fasciitis and had enhanced growth ex vivo in human blood. Importantly, the repaired isogenic strain colonized the mouse oropharynx with significantly greater bacterial burden and had significantly reduced ability to internalize into cultured epithelial cells than the acapsular carriage strain. We conducted full-genome sequencing of 81 strains cultured serially from 19 epidemiologically unrelated human subjects and discovered the common theme that mutations negatively affecting capsule biosynthesis arise in vivo in the has operon. The significantly decreased capsule production is a key factor contributing to the molecular détente between pathogen and host. Our discoveries suggest a general model for bacterial pathogens in which mutations that downregulate or ablate virulence factor production contribute to carriage. PMID:25024363

[Real-time PCR detection of Neisseria meningitidis, Haemophilus influenzae, and Streptococcus pneumoniae DNA in clinical specimens].

PubMed

Vacková, Z; Lžičařová, D; Stock, N K; Kozáková, J

2015-10-01

The study aim was to implement a molecular real-time polymerase chain reaction (PCR) assay recommended by the CDC (Centers for Disease Control and Prevention) for the detection of Neisseria meningitidis, Haemophilus influenzae, and Streptococcus pneumoniae in clinical (culture negative) specimens from patients with suspected invasive bacterial disease. Clinical specimens are referred to the National Reference Laboratory (NRL) for Meningococcal Infections, Unit for Airborne Bacterial Infections, Centre for Epidemiology and Microbiology, National Institute of Public Health from various regions of the Czech Republic. Clinical specimens are, in particular, cerebrospinal fluid, anti-coagulated blood or serum and, exceptionally, post-mortem specimens. The NRL has implemented molecular diagnosis of these bacterial pathogens involved in meningitis and sepsis from clinical specimens since 1999. The first diagnostic method was semi-nested PCR followed by electrophoretic analysis. In 2014, a molecular qualitative real-time PCR assay was implemented.

Russian vaccines against especially dangerous bacterial pathogens

PubMed Central

Feodorova, Valentina A; Sayapina, Lidiya V; Corbel, Michael J; Motin, Vladimir L

2014-01-01

In response to the epidemiological situation, live attenuated or killed vaccines against anthrax, brucellosis, cholera, glanders, plague and tularemia were developed and used for immunization of at-risk populations in the Former Soviet Union. Certain of these vaccines have been updated and currently they are used on a selective basis, mainly for high risk occupations, in the Russian Federation. Except for anthrax and cholera these vaccines currently are the only licensed products available for protection against the most dangerous bacterial pathogens. Development of improved formulations and new products is ongoing. PMID:26038506

Bacterial biofilm composition in caries and caries-free subjects.

PubMed

Wolff, D; Frese, C; Maier-Kraus, T; Krueger, T; Wolff, B

2013-01-01

Certain major pathogens such as Streptococcus mutans, Lactobacillus spp. and others have been reported to be involved in caries initiation and progression. Yet, in addition to those leading pathogens, microbial communities seem to be much more diverse and individually differing. The aim of this study, therefore, was to analyze the bacterial composition of carious dentin and the plaque of caries-free patients by using a custom-made, real-time quantitative polymerase chain reaction assay (RQ-PCR). The study included 26 patients with caries and 28 caries-free controls. Decayed tooth substance and plaque samples were harvested. Bacterial DNA was extracted and tested for the presence of 43 bacterial species or species groups using RQ-PCR. Relative quantification revealed that Propionibacterium acidifaciens was significantly more abundant in caries samples than were other microorganisms (fold change 169.12, p = 0.023). In the caries-free samples, typical health-associated species were significantly more prevalent. Unsupervised hierarchical cluster analysis showed a high abundance of P. acidifaciens in caries subjects and distinct but individually differing bacterial clusters in the caries-free subjects. The distribution of 11 bacteria allowed full discrimination between caries and caries-free subjects. Within the investigated cohort, P. acidifaciens was the only pathogen significantly more abundant in caries subjects. Cluster analysis yielded a diverse flora in caries-free subjects, whereas it was narrowed down to a small range of a few outcompeting members in caries subjects. Copyright © 2012 S. Karger AG, Basel.

Interactome analysis of longitudinal pharyngeal infection of cynomolgus macaques by group A Streptococcus.

PubMed

Shea, Patrick R; Virtaneva, Kimmo; Kupko, John J; Porcella, Stephen F; Barry, William T; Wright, Fred A; Kobayashi, Scott D; Carmody, Aaron; Ireland, Robin M; Sturdevant, Daniel E; Ricklefs, Stacy M; Babar, Imran; Johnson, Claire A; Graham, Morag R; Gardner, Donald J; Bailey, John R; Parnell, Michael J; Deleo, Frank R; Musser, James M

2010-03-09

Relatively little is understood about the dynamics of global host-pathogen transcriptome changes that occur during bacterial infection of mucosal surfaces. To test the hypothesis that group A Streptococcus (GAS) infection of the oropharynx provokes a distinct host transcriptome response, we performed genome-wide transcriptome analysis using a nonhuman primate model of experimental pharyngitis. We also identified host and pathogen biological processes and individual host and pathogen gene pairs with correlated patterns of expression, suggesting interaction. For this study, 509 host genes and seven biological pathways were differentially expressed throughout the entire 32-day infection cycle. GAS infection produced an initial widespread significant decrease in expression of many host genes, including those involved in cytokine production, vesicle formation, metabolism, and signal transduction. This repression lasted until day 4, at which time a large increase in expression of host genes was observed, including those involved in protein translation, antigen presentation, and GTP-mediated signaling. The interactome analysis identified 73 host and pathogen gene pairs with correlated expression levels. We discovered significant correlations between transcripts of GAS genes involved in hyaluronic capsule production and host endocytic vesicle formation, GAS GTPases and host fibrinolytic genes, and GAS response to interaction with neutrophils. We also identified a strong signal, suggesting interaction between host gammadelta T cells and genes in the GAS mevalonic acid synthesis pathway responsible for production of isopentenyl-pyrophosphate, a short-chain phospholipid that stimulates these T cells. Taken together, our results are unique in providing a comprehensive understanding of the host-pathogen interactome during mucosal infection by a bacterial pathogen.

CRISPR interference can prevent natural transformation and virulence acquisition during in vivo bacterial infection.

PubMed

Bikard, David; Hatoum-Aslan, Asma; Mucida, Daniel; Marraffini, Luciano A

2012-08-16

Pathogenic bacterial strains emerge largely due to transfer of virulence and antimicrobial resistance genes between bacteria, a process known as horizontal gene transfer (HGT). Clustered, regularly interspaced, short palindromic repeat (CRISPR) loci of bacteria and archaea encode a sequence-specific defense mechanism against bacteriophages and constitute a programmable barrier to HGT. However, the impact of CRISPRs on the emergence of virulence is unknown. We programmed the human pathogen Streptococcus pneumoniae with CRISPR sequences that target capsule genes, an essential pneumococcal virulence factor, and show that CRISPR interference can prevent transformation of nonencapsulated, avirulent pneumococci into capsulated, virulent strains during infection in mice. Further, at low frequencies bacteria can lose CRISPR function, acquire capsule genes, and mount a successful infection. These results demonstrate that CRISPR interference can prevent the emergence of virulence in vivo and that strong selective pressure for virulence or antibiotic resistance can lead to CRISPR loss in bacterial pathogens. Copyright © 2012 Elsevier Inc. All rights reserved.

Phylogenetic, epidemiological and functional analyses of the Streptococcus bovis/Streptococcus equinus complex through an overarching MLST scheme.

PubMed

Jans, Christoph; de Wouters, Tomas; Bonfoh, Bassirou; Lacroix, Christophe; Kaindi, Dasel Wambua Mulwa; Anderegg, Janine; Böck, Désirée; Vitali, Sabrina; Schmid, Thomas; Isenring, Julia; Kurt, Fabienne; Kogi-Makau, Wambui; Meile, Leo

2016-06-21

The Streptococcus bovis/Streptococcus equinus complex (SBSEC) comprises seven (sub)species classified as human and animal commensals, emerging opportunistic pathogens and food fermentative organisms. Changing taxonomy, shared habitats, natural competence and evidence for horizontal gene transfer pose difficulties for determining their phylogeny, epidemiology and virulence mechanisms. Thus, novel phylogenetic and functional classifications are required. An SBSEC overarching multi locus sequence type (MLST) scheme targeting 10 housekeeping genes was developed, validated and combined with host-related properties of adhesion to extracellular matrix proteins (ECM), activation of the immune responses via NF-KB and survival in simulated gastric juice (SGJ). Commensal and pathogenic SBSEC strains (n = 74) of human, animal and food origin from Europe, Asia, America and Africa were used in the MLST scheme yielding 66 sequence types and 10 clonal complexes differentiated into distinct habitat-associated and mixed lineages. Adhesion to ECMs collagen I and mucin type II was a common characteristic (23 % of strains) followed by adhesion to fibronectin and fibrinogen (19.7 %). High adhesion abilities were found for East African dairy and human blood isolate branches whereas commensal fecal SBSEC displayed low adhesion. NF-KB activation was observed for a limited number of dairy and blood isolates suggesting the potential of some pathogenic strains for reduced immune activation. Strains from dairy MLST clades displayed the highest relative survival to SGJ independently of dairy adaptation markers lacS/lacZ. Combining phylogenetic and functional analyses via SBSEC MLST enabled the clear delineation of strain clades to unravel the complexity of this bacterial group. High adhesion values shared between certain dairy and blood strains as well as the behavior of NF-KB activation are concerning for specific lineages. They highlighted the health risk among shared lineages and

Potential Factors Enabling Human Body Colonization by Animal Streptococcus dysgalactiae subsp. equisimilis Strains.

PubMed

Ciszewski, Marcin; Szewczyk, Eligia M

2017-05-01

Streptococcus dysgalactiae subsp. equisimilis (SDSE) is a pyogenic, Lancefield C or G streptococcal pathogen. Until recently, it has been considered as an exclusive animal pathogen. Nowadays, it is responsible for both animal infections in wild animals, pets, and livestock and human infections often clinically similar to the ones caused by group A streptococcus (Streptococcus pyogenes). The risk of zoonotic infection is the most significant in people having regular contact with animals, such as veterinarians, cattlemen, and farmers. SDSE is also prevalent on skin of healthy dogs, cats, and horses, which pose a risk also to people having contact with companion animals. The main aim of this study was to evaluate if there are features differentiating animal and human SDSE isolates, especially in virulence factors involved in the first stages of pathogenesis (adhesion and colonization). Equal groups of human and animal SDSE clinical strains were obtained from superficial infections (skin, wounds, abscesses). The presence of five virulence genes (prtF1, prtF2, lmb, cbp, emm type) was evaluated, as well as ability to form bacterial biofilm and produce BLIS (bacteriocin-like inhibitory substances) which are active against human skin microbiota. The study showed that the presence of genes coding for fibronectin-binding protein and M protein, as well as BLIS activity inhibiting the growth of Corynebacterium spp. strains might constitute the virulence factors which are necessary to colonize human organism, whereas they are not crucial in animal infections. Those virulence factors might be horizontally transferred from human streptococci to animal SDSE strains, enabling their ability to colonize human organism.

Participation of necroptosis in the host response to acute bacterial pneumonia

PubMed Central

Ahn, Danielle; Prince, Alice

2017-01-01

Common pulmonary pathogens, such as Streptococcus pneumoniae and Staphylococcus aureus as well as the host-adapted pathogens responsible for health care associated pneumonias such as the carbapenem-resistant Klebsiella pneumoniae and Serratia marcesens are able to activate cell death through the RIPK1/RIPK3/MLKL cascade that causes necroptosis. Necroptosis can influence the pathogenesis of pneumonia through several mechanisms. Activation of this pathway can result in the loss of specific types of immune cells, especially macrophages and in doing so contribute to host pathology through loss of their critical immunoregulatory functions. However, in other settings of infection, necroptosis promotes pathogen removal and eradication of infected cells to control excessive proinflammatory signaling. Bacterial production of pore forming toxins provides a common mechanism to activate necroptosis by diverse bacterial species, with variable consequences depending upon the specific pathogen. Included in this brief review are data demonstrating the ability of the carbapenem-resistant ST258 K. pneumoniae to activate necroptosis in the setting of pneumonia, which is counterbalanced by their suppression of CYLD expression. Exactly how necroptosis and other mechanisms of cell death are co-regulated in the response to specific pulmonary pathogens remains a topic of active investigation and may provide potential therapeutic targets in the future. PMID:28125817

Participation of Necroptosis in the Host Response to Acute Bacterial Pneumonia.

PubMed

Ahn, Danielle; Prince, Alice

2017-01-01

Common pulmonary pathogens, such as Streptococcus pneumoniae and Staphylococcus aureus, as well as the host-adapted pathogens responsible for health care-associated pneumonias, such as the carbapenem-resistant Klebsiella pneumoniae and Serratia marcecsens, are able to activate cell death through the RIPK1/RIPK3/MLKL cascade that causes necroptosis. Necroptosis can influence the pathogenesis of pneumonia through several mechanisms. Activation of this pathway can result in the loss of specific types of immune cells, especially macrophages, and, in so doing, contribute to host pathology through the loss of their critical immunoregulatory functions. However, in other settings of infection, necroptosis promotes pathogen removal and the eradication of infected cells to control excessive proinflammatory signaling. Bacterial production of pore-forming toxins provides a common mechanism to activate necroptosis by diverse bacterial species, with variable consequences depending upon the specific pathogen. Included in this brief review are data demonstrating the ability of the carbapenem-resistant ST258 K. pneumoniae to activate necroptosis in the setting of pneumonia, which is counterbalanced by their suppression of CYLD expression. Exactly how necroptosis and other mechanisms of cell death are coregulated in the response to specific pulmonary pathogens remains a topic of active investigation, and it may provide potential therapeutic targets in the future. © 2017 S. Karger AG, Basel.

Isolation and Characterization of a microRNA-size Secretable Small RNA in Streptococcus sanguinis.

PubMed

Choi, Ji-Woong; Kwon, Tae-Yub; Hong, Su-Hyung; Lee, Heon-Jin

2018-06-01

MicroRNAs in eukaryotic cells are thought to control highly complex signal transduction and other biological processes by regulating coding transcripts, accounting for their important role in cellular events in eukaryotes. Recently, a novel class of bacterial RNAs similar in size [18-22 nucleotides (nt)] to microRNAs has been reported. Herein, we describe microRNAs, small RNAs from the oral pathogen Streptococcus sanguinis. The bacteria are normally present in the oral cavities and cause endocarditis by contaminating bloodstreams. Small RNAs were analyzed by deep sequencing. Selected highly expressed small RNAs were further validated by real-time polymerase chain reaction and northern blot analyses. We found that skim milk supplement changed the expression of small RNAs S.S-1964 in tandem with the nearby SSA_0513 gene involved in vitamin B 12 conversion. We furthermore observed small RNAs secreted via bacterial membrane vesicles. Although their precise function remains unclear, secretable small RNAs may represent an entirely new area of study in bacterial genetics.

Development of a loop-mediated isothermal amplification assay for the detection of Streptococcus agalactiae in bovine milk.

PubMed

Bosward, Katrina L; House, John K; Deveridge, Amber; Mathews, Karen; Sheehy, Paul A

2016-03-01

Streptococcus agalactiae is a well-characterized bovine mastitis pathogen that is known to be highly contagious and capable of spreading rapidly in affected dairy herds. Loop-mediated isothermal amplification (LAMP) is a novel molecular diagnostic method that has the capability to provide rapid, cost-effective screening for pathogens to support on-farm disease control and eradication programs. In the current study, a LAMP test was developed to detect S. agalactiae in milk. The assay was validated on a bank of existing clinical mastitis milk samples that had previously been identified as S. agalactiae positive via traditional microbiological culture techniques and PCR. The LAMP assay was conducted on bacterial colonies and DNA extracted from milk in tube- and plate-based formats using multiple detection platforms. The 1-h assay conducted at 64 °C exhibited repeatability (coefficient of variation) of 2.07% (tube) and 8.3% (plate), sensitivity to ~20 pg of extracted DNA/reaction, and specificity against a panel of known bacterial mastitis pathogens. Of the 109 known S. agalactiae isolates assessed by LAMP directly from bacterial cells in culture, 108 were identified as positive, in accordance with PCR analysis. The LAMP analysis from the corresponding milk samples indicated that 104 of these milks exhibited a positive amplification curve. Although exhibiting some limitations, this assay provides an opportunity for rapid screening of milk samples to facilitate on-farm management of this pathogen. Copyright © 2016 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

[Study on the classification of dominant pathogens related to febrile respiratory syndrome, based on the method of Bayes discriminant analysis].

PubMed

Li, X C; Li, J S; Meng, L; Bai, Y N; Yu, D S; Liu, X N; Liu, X F; Jiang, X J; Ren, X W; Yang, X T; Shen, X P; Zhang, J W

2017-08-10

Objective: To understand the dominant pathogens of febrile respiratory syndrome (FRS) patients in Gansu province and to establish the Bayes discriminant function in order to identify the patients infected with the dominant pathogens. Methods: FRS patients were collected in various sentinel hospitals of Gansu province from 2009 to 2015 and the dominant pathogens were determined by describing the composition of pathogenic profile. Significant clinical variables were selected by stepwise discriminant analysis to establish the Bayes discriminant function. Results: In the detection of pathogens for FRS, both influenza virus and rhinovirus showed higher positive rates than those caused by other viruses (13.79%, 8.63%), that accounting for 54.38%, 13.73% of total viral positive patients. Most frequently detected bacteria would include Streptococcus pneumoniae , and haemophilus influenza (44.41%, 18.07%) that accounting for 66.21% and 24.55% among the bacterial positive patients. The original-validated rate of discriminant function, established by 11 clinical variables, was 73.1%, with the cross-validated rate as 70.6%. Conclusion: Influenza virus, Rhinovirus, Streptococcus pneumoniae and Haemophilus influenzae were the dominant pathogens of FRS in Gansu province. Results from the Bayes discriminant analysis showed both higher accuracy in the classification of dominant pathogens, and applicative value for FRS.

A bacterial siren song: intimate interactions between neutrophils and pathogenic Neisseria

PubMed Central

Criss, Alison K.; Seifert, H. Steven

2012-01-01

Preface Neisseria gonorrhoeae and Neisseria meningitidis are Gram-negative bacterial pathogens that are exquisitely adapted for growth at human mucosal surfaces and for efficient transmission between hosts. One factor that is essential to neisserial pathogenesis is the interaction between the bacteria and neutrophils, which are recruited in high numbers during infection. Although this vigorous host response could simply reflect effective immune recognition of the bacteria, there is mounting evidence that in fact these obligate human pathogens manipulate the innate immune response to promote infectious processes. This Review summarizes the mechanisms used by pathogenic neisseriae to resist and modulate the antimicrobial activities of neutrophils. It also details some of the major outstanding questions about the Neisseria–neutrophil relationship and proposes potential benefits of this relationship for the pathogen. PMID:22290508

Antimicrobial inflammasomes: unified signalling against diverse bacterial pathogens.

PubMed

Eldridge, Matthew J G; Shenoy, Avinash R

2015-02-01

Inflammasomes - molecular platforms for caspase-1 activation - have emerged as common hubs for a number of pathways that detect and respond to bacterial pathogens. Caspase-1 activation results in the secretion of bioactive IL-1β and IL-18 and pyroptosis, and thus launches a systemic immune and inflammatory response. In this review we discuss signal transduction leading to 'canonical' and 'non-canonical' activation of caspase-1 through the involvement of upstream caspases. Recent studies have identified a growing number of regulatory networks involving guanylate binding proteins, protein kinases, ubiquitylation and necroptosis related pathways that modulate inflammasome responses and immunity to bacterial infection. By being able to respond to extracellular, vacuolar and cytosolic bacteria, their cytosolic toxins or ligands for cell surface receptors, inflammasomes have emerged as important sentinels of infection. Copyright © 2014 Elsevier Ltd. All rights reserved.

Point detection of bacterial and viral pathogens using oral samples

NASA Astrophysics Data System (ADS)

Malamud, Daniel

2008-04-01

Oral samples, including saliva, offer an attractive alternative to serum or urine for diagnostic testing. This is particularly true for point-of-use detection systems. The various types of oral samples that have been reported in the literature are presented here along with the wide variety of analytes that have been measured in saliva and other oral samples. The paper focuses on utilizing point-detection of infectious disease agents, and presents work from our group on a rapid test for multiple bacterial and viral pathogens by monitoring a series of targets. It is thus possible in a single oral sample to identify multiple pathogens based on specific antigens, nucleic acids, and host antibodies to those pathogens. The value of such a technology for detecting agents of bioterrorism at remote sites is discussed.

Interactions of Seedborne Bacterial Pathogens with Host and Non-Host Plants in Relation to Seed Infestation and Seedling Transmission

PubMed Central

Dutta, Bhabesh; Gitaitis, Ronald; Smith, Samuel; Langston, David

2014-01-01

The ability of seed-borne bacterial pathogens (Acidovorax citrulli, Clavibacter michiganensis subsp. michiganensis, Pseudomonas syringae pv. tomato, Xanthomonas euvesicatoria, and Pseudomonas syringae pv. glycinea) to infest seeds of host and non-host plants (watermelon, tomato, pepper, and soybean) and subsequent pathogen transmission to seedlings was investigated. A non-pathogenic, pigmented strain of Serratia marcescens was also included to assess a null-interacting situation with the same plant species. Flowers of host and non-host plants were inoculated with 1×106 colony forming units (CFUs)/flower for each bacterial species and allowed to develop into fruits or umbels (in case of onion). Seeds harvested from each host/non-host bacterial species combination were assayed for respective bacteria by plating on semi-selective media. Additionally, seedlots for each host/non-host bacterial species combination were also assayed for pathogen transmission by seedling grow-out (SGO) assays under greenhouse conditions. The mean percentage of seedlots infested with compatible and incompatible pathogens was 31.7 and 30.9% (by plating), respectively and they were not significantly different (P = 0.67). The percentage of seedlots infested with null-interacting bacterial species was 16.8% (by plating) and it was significantly lower than the infested lots generated with compatible and incompatible bacterial pathogens (P = 0.03). None of the seedlots with incompatible/null-interacting bacteria developed symptoms on seedlings; however, when seedlings were assayed for epiphytic bacterial presence, 19.5 and 9.4% of the lots were positive, respectively. These results indicate that the seeds of non-host plants can become infested with incompatible and null-interacting bacterial species through flower colonization and they can be transmitted via epiphytic colonization of seedlings. In addition, it was also observed that flowers and seeds of non-host plants can be colonized

Characterization of multi-drug tolerant persister cells in Streptococcus suis

PubMed Central

2014-01-01

Background Persister cells constitute a subpopulation of dormant cells within a microbial population which are genetically identical but phenotypically different to regular cells. Notably, persister cells show an elevated tolerance to antimicrobial agents. Thus, they are considered to represent a microbial ‘bet-hedging’ strategy and are of particular importance in pathogenic bacteria. Results We studied the ability of the zoonotic pathogen Streptococcus (S.) suis to form multi-drug tolerant variants and identified persister cells dependent on the initial bacterial growth phase. We observed lower numbers of persisters in exponential phase cultures than in stationary growth phase populations. S. suis persister cells showed a high tolerance to a variety of antibiotics, and the phenotype was not inherited as tested with four passages of S. suis populations. Furthermore, we provide evidence that the persister phenotype is related to expression of genes involved in general metabolic pathways since we found higher numbers of persister cells in a mutant strain defective in the catabolic arginine deiminase system as compared to its parental wild type strain. Finally, we observed persister cell formation also in other S. suis strains and pathogenic streptococcal species. Conclusions Taken together, this is the first study that reports multi-drug tolerant persister cells in the zoonotic pathogen S. suis. PMID:24885389

Characterization of multi-drug tolerant persister cells in Streptococcus suis.

PubMed

Willenborg, Jörg; Willms, Daniela; Bertram, Ralph; Goethe, Ralph; Valentin-Weigand, Peter

2014-05-12

Persister cells constitute a subpopulation of dormant cells within a microbial population which are genetically identical but phenotypically different to regular cells. Notably, persister cells show an elevated tolerance to antimicrobial agents. Thus, they are considered to represent a microbial 'bet-hedging' strategy and are of particular importance in pathogenic bacteria. We studied the ability of the zoonotic pathogen Streptococcus (S.) suis to form multi-drug tolerant variants and identified persister cells dependent on the initial bacterial growth phase. We observed lower numbers of persisters in exponential phase cultures than in stationary growth phase populations. S. suis persister cells showed a high tolerance to a variety of antibiotics, and the phenotype was not inherited as tested with four passages of S. suis populations. Furthermore, we provide evidence that the persister phenotype is related to expression of genes involved in general metabolic pathways since we found higher numbers of persister cells in a mutant strain defective in the catabolic arginine deiminase system as compared to its parental wild type strain. Finally, we observed persister cell formation also in other S. suis strains and pathogenic streptococcal species. Taken together, this is the first study that reports multi-drug tolerant persister cells in the zoonotic pathogen S. suis.

Identification of candidate periodontal pathogens and beneficial species by quantitative 16S clonal analysis.

PubMed

Kumar, Purnima S; Griffen, Ann L; Moeschberger, Melvin L; Leys, Eugene J

2005-08-01

Most studies of the bacterial etiology of periodontitis have used either culture-based or targeted DNA approaches, and so it is likely that pathogens remain undiscovered. The purpose of this study was to use culture-independent, quantitative analysis of biofilms associated with chronic periodontitis and periodontal health to identify pathogens and beneficial species. Samples from subjects with periodontitis and controls were analyzed using ribosomal 16S cloning and sequencing. Several genera, many of them uncultivated, were associated with periodontitis, the most numerous of which were gram positive, including Peptostreptococcus and Filifactor. The genera Megasphaera and Desulfobulbus were elevated in periodontitis, and the levels of several species or phylotypes of Campylobacter, Selenomonas, Deferribacteres, Dialister, Catonella, Tannerella, Streptococcus, Atopobium, Eubacterium, and Treponema were elevated in disease. Streptococcus and Veillonella spp. were found in high numbers in all samples and accounted for a significantly greater fraction of the microbial community in healthy subjects than in those with periodontitis. The microbial profile of periodontal health also included the less-abundant genera Campylobacter, Abiotrophia, Gemella, Capnocytophaga, and Neisseria. These newly identified candidates outnumbered Porphyromonas gingivalis and other species previously implicated as periodontopathogens, and it is not clear if newly identified and more numerous species may play a more important role in pathogenesis. Finally, more differences were found in the bacterial profile between subjects with periodontitis and healthy subjects than between deep and shallow sites within the same subject. This suggests that chronic periodontitis is the result of a global perturbation of the oral bacterial ecology rather than a disease-site specific microbial shift.

Galleria mellonella larvae as an infection model for group A streptococcus

PubMed Central

Loh, Jacelyn MS; Adenwalla, Nazneen; Wiles, Siouxsie; Proft, Thomas

2013-01-01

Group A streptococcus is a strict human pathogen that can cause a wide range of diseases, such as tonsillitis, impetigo, necrotizing fasciitis, toxic shock, and acute rheumatic fever. Modeling human diseases in animals is complicated, and rapid, simple, and cost-effective in vivo models of GAS infection are clearly lacking. Recently, the use of non-mammalian models to model human disease is starting to re-attract attention. Galleria mellonella larvae, also known as wax worms, have been investigated for modeling a number of bacterial pathogens, and have been shown to be a useful model to study pathogenesis of the M3 serotype of GAS. In this study we provide further evidence of the validity of the wax worm model by testing different GAS M-types, as well as investigating the effect of bacterial growth phase and incubation temperature on GAS virulence in this model. In contrast to previous studies, we show that the M-protein, among others, is an important virulence factor that can be effectively modeled in the wax worm. We also highlight the need for a more in-depth investigation of the effects of experimental design and wax worm supply before we can properly vindicate the wax worm model for studying GAS pathogenesis. PMID:23652836

Streptococcus suis: a new emerging or an old neglected zoonotic pathogen?

PubMed

Gottschalk, Marcelo; Xu, Jianguo; Calzas, Cynthia; Segura, Mariela

2010-03-01

Infections caused by Streptococcus suis are considered a global and an economical problem in the swine industry. Moreover, S. suis is an agent of zoonosis that afflicts people in close contact with infected pigs or pork-derived products. Although sporadic cases of S. suis infections in humans (mainly meningitis) have been reported during the last 40 years, a large outbreak due to this pathogen emerged in the summer of 2005 in China. The severity of the infection in humans during the outbreak, such as a shorter incubation time, more rapid disease progression and higher rate of mortality, attracted a lot of attention from the scientific community and the general press. In fact, the number of publications on S. suis (including the number of reported human cases) has significantly increased during recent years. In this article we critically review the present knowledge on S. suis infection in humans, we discuss the hypotheses that may explain the 2005 outbreak and the repercussion of such an episode on the scientific community.

Population-based surveillance for bacterial meningitis in China, September 2006-December 2009.

PubMed

Li, Yixing; Yin, Zundong; Shao, Zhujun; Li, Manshi; Liang, Xiaofeng; Sandhu, Hardeep S; Hadler, Stephen C; Li, Junhong; Sun, Yinqi; Li, Jing; Zou, Wenjing; Lin, Mei; Zuo, Shuyan; Mayer, Leonard W; Novak, Ryan T; Zhu, Bingqing; Xu, Li; Luo, Huiming

2014-01-01

During September 2006-December 2009, we conducted active population and sentinel laboratory-based surveillance for bacterial meningitis pathogens, including Streptococcus pneumoniae, Neisseria meningitidis, and Haemophilus influenzae type b, in 4 China prefectures. We identified 7,876 acute meningitis and encephalitis syndrome cases, including 6,388 among prefecture residents. A total of 833 resident cases from sentinel hospitals met the World Health Organization case definition for probable bacterial meningitis; 339 of these cases were among children <5 years of age. Laboratory testing confirmed bacterial meningitis in 74 of 3,391 tested cases. The estimated annual incidence (per 100,000 population) of probable bacterial meningitis ranged from 1.84 to 2.93 for the entire population and from 6.95 to 22.30 for children <5 years old. Active surveillance with laboratory confirmation has provided a population-based estimate of the number of probable bacterial meningitis cases in China, but more complete laboratory testing is needed to better define the epidemiology of the disease in this country.

9230 FECAL ENTEROCOCCUS/STREPTOCOCCUS GROUPS

EPA Science Inventory

In 1903 the genus name Enterococcus was proposed for gram-positive, catalase-negative, coccoid-shaped bacterial of intestinal origin. Several years later, it was suggested that the genus name be changed to Streptococcus because of the organisms' ability to form chains of coccoid...

Infection of an Insect Vector with a Bacterial Plant Pathogen Increases Its Propensity for Dispersal

PubMed Central

Coy, Monique R.; Stelinski, Lukasz L.; Pelz-Stelinski, Kirsten S.

2015-01-01

The spread of vector-transmitted pathogens relies on complex interactions between host, vector and pathogen. In sessile plant pathosystems, the spread of a pathogen highly depends on the movement and mobility of the vector. However, questions remain as to whether and how pathogen-induced vector manipulations may affect the spread of a plant pathogen. Here we report for the first time that infection with a bacterial plant pathogen increases the probability of vector dispersal, and that such movement of vectors is likely manipulated by a bacterial plant pathogen. We investigated how Candidatus Liberibacter asiaticus (CLas) affects dispersal behavior, flight capacity, and the sexual attraction of its vector, the Asian citrus psyllid (Diaphorina citri Kuwayama). CLas is the putative causal agent of huanglongbing (HLB), which is a disease that threatens the viability of commercial citrus production worldwide. When D. citri developed on CLas-infected plants, short distance dispersal of male D. citri was greater compared to counterparts reared on uninfected plants. Flight by CLas-infected D. citri was initiated earlier and long flight events were more common than by uninfected psyllids, as measured by a flight mill apparatus. Additionally, CLas titers were higher among psyllids that performed long flights than psyllid that performed short flights. Finally, attractiveness of female D. citri that developed on infected plants to male conspecifics increased proportionally with increasing CLas bacterial titers measured within female psyllids. Our study indicates that the phytopathogen, CLas, may manipulate movement and mate selection behavior of their vectors, which is a possible evolved mechanism to promote their own spread. These results have global implications for both current HLB models of disease spread and control strategies. PMID:26083763

Bacterial genomics reveal the complex epidemiology of an emerging pathogen in arctic and boreal ungulates

USGS Publications Warehouse

Forde, Taya L.; Orsel, Karin; Zadoks, Ruth N.; Biek, Roman; Adams, Layne G.; Checkley, Sylvia L.; Davison, Tracy; De Buck, Jeroen; Dumond, Mathieu; Elkin, Brett T.; Finnegan, Laura; Macbeth, Bryan J.; Nelson, Cait; Niptanatiak, Amanda; Sather, Shane; Schwantje, Helen M.; van der Meer, Frank; Kutz, Susan J.

2016-01-01

Northern ecosystems are currently experiencing unprecedented ecological change, largely driven by a rapidly changing climate. Pathogen range expansion, and emergence and altered patterns of infectious disease, are increasingly reported in wildlife at high latitudes. Understanding the causes and consequences of shifting pathogen diversity and host-pathogen interactions in these ecosystems is important for wildlife conservation, and for indigenous populations that depend on wildlife. Among the key questions are whether disease events are associated with endemic or recently introduced pathogens, and whether emerging strains are spreading throughout the region. In this study, we used a phylogenomic approach to address these questions of pathogen endemicity and spread for Erysipelothrix rhusiopathiae, an opportunistic multi-host bacterial pathogen associated with recent mortalities in arctic and boreal ungulate populations in North America. We isolated E. rhusiopathiae from carcasses associated with large-scale die-offs of muskoxen in the Canadian Arctic Archipelago, and from contemporaneous mortality events and/or population declines among muskoxen in northwestern Alaska and caribou and moose in western Canada. Bacterial genomic diversity differed markedly among these locations; minimal divergence was present among isolates from muskoxen in the Canadian Arctic, while in caribou and moose populations, strains from highly divergent clades were isolated from the same location, or even from within a single carcass. These results indicate that mortalities among northern ungulates are not associated with a single emerging strain of E. rhusiopathiae, and that alternate hypotheses need to be explored. Our study illustrates the value and limitations of bacterial genomic data for discriminating between ecological hypotheses of disease emergence, and highlights the importance of studying emerging pathogens within the broader context of environmental and host factors.

Short communication: Environmental mastitis pathogen counts in freestalls bedded with composted and fresh recycled manure solids.

PubMed

Cole, K J; Hogan, J S

2016-02-01

An experiment was conducted to compare bacterial counts of environmental mastitis pathogens in composted recycled manure solids bedding with those in fresh recycled manure solids. Eighteen Holstein cows were housed in 1 pen with 18 stalls. One row of 9 freestalls included mattresses and was bedded weekly with composted recycled manure solids. The second row of 9 freestalls included mattresses and was bedded weekly with fresh recycled manure solids. The back one-third of stalls toward the alleyway was covered in 25 to 50 mm of bedding. Samples were taken from the back one-third of 4 stalls for both treatments on d 0, 1, 2, and 6 of each week. After 3 wk, bedding treatments were switched between rows, making the total duration 6 wk. Mean total gram-negative bacterial counts were approximately 0.5 log10 cfu/g of dry matter lower in the composted recycled manure solids on d 0 compared with fresh recycled manure solids. Klebsiella species, coliform, and Streptococcus species counts were at least 1.0 log10 cfu/g of dry matter lower in composted compared with fresh recycled manure solids on d 0. Only gram-negative bacterial counts on d 1 were reduced in composted recycled manure solids compared with fresh recycled manure solids. Differences were not observed between treatments in gram-negative bacterial, coliform, Klebsiella species, or Streptococcus species counts on d 2 and 6. Ash content was higher in composted recycled manure solids compared with fresh recycled manure solids on d 0, 1, 2, and 6. Despite the increase in ash after composting, bacterial counts of mastitis pathogens in composted recycled manure solids were comparable with those in fresh recycled manure when used as freestall bedding. Copyright © 2016 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Streptococcus suis - The "Two Faces" of a Pathobiont in the Porcine Respiratory Tract.

PubMed

Vötsch, Désirée; Willenborg, Maren; Weldearegay, Yenehiwot B; Valentin-Weigand, Peter

2018-01-01

Streptococcus (S.) suis is a frequent early colonizer of the upper respiratory tract of pigs. In fact, it is difficult to find S. suis -free animals under natural conditions, showing the successful adaptation of this pathogen to its porcine reservoir host. On the other hand, S. suis can cause life-threatening diseases and represents the most important bacterial cause of meningitis in pigs worldwide. Notably, S. suis can also cause zoonotic infections, such as meningitis, septicemia, endocarditis, and other diseases in humans. In Asia, it is classified as an emerging zoonotic pathogen and currently considered as one of the most important causes of bacterial meningitis in adults. The "two faces" of S. suis , one of a colonizing microbe and the other of a highly invasive pathogen, have raised many questions concerning the interpretation of diagnostic detection and the definition of virulence. Thus, one major research challenge is the identification of virulence-markers which allow differentiation of commensal and virulent strains. This is complicated by the high phenotypic and genotypic diversity of S. suis , as reflected by the occurrence of (at least) 33 capsular serotypes. In this review, we present current knowledge in the context of S. suis as a highly diverse pathobiont in the porcine respiratory tract that can exploit disrupted host homeostasis to flourish and promote inflammatory processes and invasive diseases in pigs and humans.

Nested PCR Assay for Eight Pathogens: A Rapid Tool for Diagnosis of Bacterial Meningitis.

PubMed

Bhagchandani, Sharda P; Kubade, Sushant; Nikhare, Priyanka P; Manke, Sonali; Chandak, Nitin H; Kabra, Dinesh; Baheti, Neeraj N; Agrawal, Vijay S; Sarda, Pankaj; Mahajan, Parikshit; Ganjre, Ashish; Purohit, Hemant J; Singh, Lokendra; Taori, Girdhar M; Daginawala, Hatim F; Kashyap, Rajpal S

2016-02-01

Bacterial meningitis is a dreadful infectious disease with a high mortality and morbidity if remained undiagnosed. Traditional diagnostic methods for bacterial meningitis pose a challenge in accurate identification of pathogen, making prognosis difficult. The present study is therefore aimed to design and evaluate a specific and sensitive nested 16S rDNA genus-based polymerase chain reaction (PCR) assay using clinical cerebrospinal fluid (CSF) for rapid diagnosis of eight pathogens causing the disease. The present work was dedicated to development of an in-house genus specific 16S rDNA nested PCR covering pathogens of eight genera responsible for causing bacterial meningitis using newly designed as well as literature based primers for respective genus. A total 150 suspected meningitis CSF obtained from the patients admitted to Central India Institute of Medical Sciences (CIIMS), India during the period from August 2011 to May 2014, were used to evaluate clinical sensitivity and clinical specificity of optimized PCR assays. The analytical sensitivity and specificity of our newly designed genus-specific 16S rDNA PCR were found to be ≥92%. With such a high sensitivity and specificity, our in-house nested PCR was able to give 100% sensitivity in clinically confirmed positive cases and 100% specificity in clinically confirmed negative cases indicating its applicability in clinical diagnosis. Our in-house nested PCR system therefore can diagnose the accurate pathogen causing bacterial meningitis and therefore be useful in selecting a specific treatment line to minimize morbidity. Results are obtained within 24 h and high sensitivity makes this nested PCR assay a rapid and accurate diagnostic tool compared to traditional culture-based methods.

Comparative genomics of the bacterial genus Streptococcus illuminates evolutionary implications of species groups.

PubMed

Gao, Xiao-Yang; Zhi, Xiao-Yang; Li, Hong-Wei; Klenk, Hans-Peter; Li, Wen-Jun

2014-01-01

Members of the genus Streptococcus within the phylum Firmicutes are among the most diverse and significant zoonotic pathogens. This genus has gone through considerable taxonomic revision due to increasing improvements of chemotaxonomic approaches, DNA hybridization and 16S rRNA gene sequencing. It is proposed to place the majority of streptococci into "species groups". However, the evolutionary implications of species groups are not clear presently. We use comparative genomic approaches to yield a better understanding of the evolution of Streptococcus through genome dynamics, population structure, phylogenies and virulence factor distribution of species groups. Genome dynamics analyses indicate that the pan-genome size increases with the addition of newly sequenced strains, while the core genome size decreases with sequential addition at the genus level and species group level. Population structure analysis reveals two distinct lineages, one including Pyogenic, Bovis, Mutans and Salivarius groups, and the other including Mitis, Anginosus and Unknown groups. Phylogenetic dendrograms show that species within the same species group cluster together, and infer two main clades in accordance with population structure analysis. Distribution of streptococcal virulence factors has no obvious patterns among the species groups; however, the evolution of some common virulence factors is congruous with the evolution of species groups, according to phylogenetic inference. We suggest that the proposed streptococcal species groups are reasonable from the viewpoints of comparative genomics; evolution of the genus is congruent with the individual evolutionary trajectories of different species groups.

Comparative Genomics of the Bacterial Genus Streptococcus Illuminates Evolutionary Implications of Species Groups

PubMed Central

Gao, Xiao-Yang; Zhi, Xiao-Yang; Li, Hong-Wei; Klenk, Hans-Peter; Li, Wen-Jun

2014-01-01

Members of the genus Streptococcus within the phylum Firmicutes are among the most diverse and significant zoonotic pathogens. This genus has gone through considerable taxonomic revision due to increasing improvements of chemotaxonomic approaches, DNA hybridization and 16S rRNA gene sequencing. It is proposed to place the majority of streptococci into “species groups”. However, the evolutionary implications of species groups are not clear presently. We use comparative genomic approaches to yield a better understanding of the evolution of Streptococcus through genome dynamics, population structure, phylogenies and virulence factor distribution of species groups. Genome dynamics analyses indicate that the pan-genome size increases with the addition of newly sequenced strains, while the core genome size decreases with sequential addition at the genus level and species group level. Population structure analysis reveals two distinct lineages, one including Pyogenic, Bovis, Mutans and Salivarius groups, and the other including Mitis, Anginosus and Unknown groups. Phylogenetic dendrograms show that species within the same species group cluster together, and infer two main clades in accordance with population structure analysis. Distribution of streptococcal virulence factors has no obvious patterns among the species groups; however, the evolution of some common virulence factors is congruous with the evolution of species groups, according to phylogenetic inference. We suggest that the proposed streptococcal species groups are reasonable from the viewpoints of comparative genomics; evolution of the genus is congruent with the individual evolutionary trajectories of different species groups. PMID:24977706

Modeling of 3D Structure of Chimeric Constructs Based on Hemagglutinin of Influenza Virus and Immunogenic Epitopes of Streptococcus Agalactiae.

PubMed

Fedorova, E A; Smolonogina, T A; Isakova-Sivak, I N; Koren'kov, D A; Kotomina, T S; Leont'eva, G F; Suvorov, A N; Rudenko, L G

2018-04-01

A project of an experimental recombinant vector vaccine for prevention of diseases caused by pathogenic streptococci based on ScaAB lipoprotein of Streptococcus agalactiae and a coldadapted strain of live influenza vaccine as a vector was developed. The sequence of ScaAB lipoprotein was analyzed and fragments forming immunodominant epitopes were determined. Chimeric molecules of influenza virus hemagglutinin H7 carrying insertions of bacterial origin were constructed. Based on the results of simulation, the most promising variants were selected; they represented fragments of lipoprotein ScaAB lacking N-terminal domain bound to hemagglutinin via a flexible linker. These insertions should minimally modulate the properties of the influenza strain, while retaining potential immunogenicity to a wide group of pathogenic streptococci.

Rapid identification of pathogenic streptococci isolated from moribund red tilapia (Oreochromis spp.).

PubMed

Abdelsalam, Mohamed; Elgendy, Mamdouh Y; Shaalan, Mohamed; Moustafa, Mohamed; Fujino, Masayuki

2017-03-01

Accurate and rapid identification of bacterial pathogens of fish is essential for the effective treatment and speedy control of infections. Massive mortalities in market-sized red tilapia (Oreochromis spp.) were noticed in mariculture concrete ponds in northern Egypt. Histopathological examination revealed marked congestion in the central vein of the liver with the presence of bacterial aggregates inside the lumen and in the vicinity of the central vein. A total of 12 isolates of streptococci were obtained from the moribund fish. This study documented the ability of the MicroSeq 500 16S bacterial sequencing method to accurately identify Streptococcus agalactiae and S. dysgalactiae mixed infections from moribund red tilapia that were difficult to be recognised by the commercial biochemical systems. The continuously decreasing cost of the sequencing technique should encourage its application in routine diagnostic procedures.

Treatable Bacterial Infections Are Underrecognized Causes of Fever in Ethiopian Children

PubMed Central

Aarsland, Sara J.; Castellanos-Gonzalez, Alejandro; Lockamy, Kameron P.; Mulu-Droppers, Ruth; Mulu, Moges; White, A. Clinton; Cabada, Miguel M.

2012-01-01

Febrile illnesses remain a major cause of morbidity and mortality in resource-poor countries, but too often, tests are not available to determine the causes, leading to misdiagnosis and inappropriate treatment. To determine the cause of febrile illnesses, we recovered the malaria smears from 102 children presenting with fever to Soddo Christian Hospital in Wolaitta Soddo, Ethiopia. DNA was isolated from the smears and evaluated by real-time polymerase chain reaction. We identified pathogen DNA with probes for Plasmodium spp., Streptococcus pneumoniae, Rickettsia spp., Salmonella spp., and Borrelia spp. Overall, we showed that it is possible to isolate high-quality DNA and identify treatable pathogens from malaria blood smears. Furthermore, our data showed that bacterial pathogens (especially Pneumococcus, Rickettsia spp., and Borrelia spp.) are common and frequently unrecognized but treatable causes of febrile illnesses in Ethiopian children. PMID:22764303

Bacteremia due to Streptococcus tigurinus: A case report and literature review.

PubMed

Hirai, Jun; Sakanashi, Daisuke; Hagihara, Mao; Haranaga, Shusaku; Uechi, Kohei; Kato, Hideo; Hamada, Hiroyuki; Nishiyama, Naoya; Koizumi, Yusuke; Suematsu, Hiroyuki; Yamagishi, Yuka; Fujita, Jiro; Mikamo, Hiroshige

2016-11-01

Gene sequence analysis methods, including 16S rRNA identification, allows accurate identification of Streptococcus species, which include phenotypically closely related species that are difficult to differentiate using conventional chemical methods. We report a case of bacteremia due to Streptococcus tigurinus, identified by 16S rRNA, in a 72-year-old woman with gastrointestinal cancer and ascites. She was hospitalized to undergo elective tumor-related surgery. Five days prior to undergoing surgery, she developed a fever with no obvious source of infection. Blood cultures identified gram-positive cocci. The patient's bacteremia was initially thought to be caused by an Enterococcus species, given her underlying gastrointestinal disease. However, alpha-hemolytic, mucoid, circular colonies were observed on sheep blood agar the following day. Although matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and biochemical testing suggested Streptococcus pneumoniae, we conducted further investigation to identify the bacterium, as the patient had no symptoms of infections usually related with S. pneumoniae such as pneumonia, meningitis, or sinusitis, and the bacteremia occurred 30 days after hospitalization. Finally, the gram-positive cocci were identified as S. tigurinus, assigned to the Streptococcus mitis group in 2012. Although the origin of infection was unclear, it was suspected that peritonitis or bacterial translocation from the gastrointestinal tract caused the bacteremia. This novel species was recently reported as being extremely pathogenic and different from other Streptococcus species. It has been reported to occur in cases of infectious endocarditis and bacteremia. In this article, we reviewed previous reports of S. tigurinus infection and summarized the clinical and pathogenetic features. Copyright © 2016 Japanese Society of Chemotherapy and The Japanese Association for Infectious Diseases. Published by Elsevier Ltd. All rights

The PerR-Regulated P1B-4-Type ATPase (PmtA) Acts as a Ferrous Iron Efflux Pump in Streptococcus pyogenes.

PubMed

Turner, Andrew G; Ong, Cheryl-Lynn Y; Djoko, Karrera Y; West, Nicholas P; Davies, Mark R; McEwan, Alastair G; Walker, Mark J

2017-06-01

Streptococcus pyogenes (group A Streptococcus [GAS]) is an obligate human pathogen responsible for a broad spectrum of human disease. GAS has a requirement for metal homeostasis within the human host and, as such, tightly modulates metal uptake and efflux during infection. Metal acquisition systems are required to combat metal sequestration by the host, while metal efflux systems are essential to protect against metal overload poisoning. Here, we investigated the function of PmtA ( P erR-regulated m etal t ransporter A ), a P 1B-4 -type ATPase efflux pump, in invasive GAS M1T1 strain 5448. We reveal that PmtA functions as a ferrous iron [Fe(II)] efflux system. In the presence of high Fe(II) concentrations, the 5448Δ pmtA deletion mutant exhibited diminished growth and accumulated 5-fold-higher levels of intracellular Fe(II) than did the wild type and the complemented mutant. The 5448Δ pmtA deletion mutant also showed enhanced susceptibility to killing by the Fe-dependent antibiotic streptonigrin as well as increased sensitivity to hydrogen peroxide and superoxide. We suggest that the PerR-mediated control of Fe(II) efflux by PmtA is important for bacterial defense against oxidative stress. PmtA represents an exemplar for an Fe(II) efflux system in a host-adapted Gram-positive bacterial pathogen. Copyright © 2017 American Society for Microbiology.

Rhamnolipids from non-pathogenic Burkholderia thailandensis E264: Physicochemical characterization, antimicrobial and antibiofilm efficacy against oral hygiene related pathogens.

PubMed

Elshikh, Mohamed; Funston, Scott; Chebbi, Alif; Ahmed, Syed; Marchant, Roger; Banat, Ibrahim M

2017-05-25

Biosurfactants are naturally occurring surface active compounds that have mainly been exploited for environmental applications and consumer products, with their biomedical efficacy an emerging area of research. Rhamnolipids area major group of biosurfactants that have been reported for their antimicrobial and antibiofilm efficacy. One of the main limiting factors for scaled up production and downstream applications of rhamnolipids is the fact that they are predominantly produced from the opportunistic pathogen Pseudomonas aeruginosa. In this article, we have reported the production and characterisation of long chain rhamnolipids from non-pathogenic Burkholderia thailandensis E264 (ATCC 700388). We have also investigated the antibacterial and antibiofilm properties of these rhamnolipids against some oral pathogens (Streptococcus oralis, Actinomyces naeslundii, Neisseria mucosa and Streptococcus sanguinis), important for oral health and hygiene. Treating these bacteria with different concentrations of long chain rhamnolipids resulted in a reduction of 3-4 log of bacterial viability, placing these rhamnolipids close to being classified as biocidal. Investigating long chain rhamnolipid efficacy as antibiofilm agents for prospective oral-related applications revealed good potency against oral-bacteria biofilms in a co-incubation experiments, in a pre-coated surface format, in disrupting immature biofilms and has shown excellent combination effect with Lauryl Sodium Sulphate which resulted in a drastic decrease in its minimal inhibitory concentration against different bacteria. Investigating the rhamnolipid permeabilization effect along with their ability to induce the formation of reactive oxygen species has shed light on the mechanism through which inhibition/killing of bacteria may occur. Copyright © 2017 Elsevier B.V. All rights reserved.

Multiplex polymerase chain reaction assay developed to diagnose adult bacterial meningitis in Taiwan.

PubMed

Lee, Chi-Tsung; Hsiao, Kuang-Ming; Chen, Jin-Cherng; Su, Cheng-Chuan

2015-11-01

Acute bacterial meningitis causes high morbidity and mortality; the associated clinical symptoms often are insensitive or non-specific; and the pathogenic bacteria are geographically diverse. Clinical diagnosis requires a rapid and accurate methodology. This study aimed to develop a new multiplex polymerase chain reaction (mPCR) assay to detect simultaneously six major bacteria that cause adult bacterial meningitis in Taiwan: Klebsiella pneumoniae, Pseudomonas aeruginosa, Streptococcus pneumoniae, Staphylococcus aureus, Escherichia coli, and Acinetobacter baumannii. Species-specific primers for the six bacteria were developed using reference strains. The specificities of the mPCRs for these bacteria were validated, and the sensitivities were evaluated via serial dilutions. The mPCR assay specifically detected all of the six pathogens, particularly with sensitivities of 12 colony forming units (CFU)/mL, 90 CFU/mL, and 390 CFU/mL for E. coli, S. pneumoniae, and K. pneumoniae, respectively. This mPCR assay is a rapid and specific tool to detect the six major bacterial pathogens that cause acute adult meningitis in Taiwan, particularly sensitive for detecting E. coli, S. pneumoniae, and K. pneumoniae. The assay may facilitate early diagnosis and guidance for antimicrobial therapy for adult patients with this deadly disease in Taiwan. © 2015 APMIS. Published by John Wiley & Sons Ltd.

AUTOMATED BIOCHEMICAL IDENTIFICATION OF BACTERIAL FISH PATHOGENS USING THE ABBOTT QUANTUM II

EPA Science Inventory

The Quantum II, originally designed by Abbott Diagnostics for automated rapid identification of members of Enterobacteriaceae, was adapted for the identification of bacterial fish pathogens. he instrument operates as a spectrophotometer at a wavelength of 492.600 nm. ample cartri...

Frequency and antimicrobial susceptibility of aerobic bacterial vaginal isolates.

PubMed

Tariq, Nabia; Jaffery, Tara; Ayub, Rukhsana; Alam, Ali Yawar; Javid, Mahmud Haider; Shafique, Shamsa

2006-03-01

To determine the frequency and antimicrobial susceptibility of aerobic bacterial isolates from high vaginal swab cultures. Cross-sectional survey. Shifa International Hospital, Islamabad, from January 2003 to February 2004. The subjects included 136 symptomatic women attending Obstetrics and Gynecology Out-Patient Department. A proforma was filled to document the demographic details, presenting complaint and examination findings. High vaginal swabs were taken for gram staining, culture and antimicrobial sensitivity testing using standard microbiologic techniques. Normal flora was isolated in 30% of the cases, followed by Candida spp. (21.3%), Enterococcus spp. (14.7%), E.coli (10.2%), Beta hemolytic Streptococcus spp. (7.3%), Staphylococcus spp. (4.4%), Enterobacter spp. (4.4%), while Streptococcus pyogenes, Staphylococcus epidermidis and Klebsiella spp. were isolated 1.5% each. Enterococcus, Staphylococcus and Streptococcus were mostly sensitive to penicillin and amoxicillin while E.coli and Klebsiella were sensitive to (piperacillin-Tazobactum, Imipenem and vancomycin. Enterococci species showed significant resistance to aminoglycoside antibiotics (68.8% to 81.3%) resistance to vancomycin was 5%. Thirty percent of symptomatic patients had normal flora on culture. Candida spp was the most frequent pathogen isolated. Co-amoxiclav should be used as empiric therapy until culture-sensitivity report is available.

Ozone disinfection of home nebulizers effectively kills common cystic fibrosis bacterial pathogens.

PubMed

Towle, Dana; Baker, Vanisha; Schramm, Craig; O'Brien, Matthew; Collins, Melanie S; Feinn, Richard; Murray, Thomas S

2018-05-01

The Cystic Fibrosis Foundation (CFF) recommends routine nebulizer disinfection for patients but compliance is challenging due to the heavy burden of home care. SoClean® is a user friendly ozone based home disinfection device currently for home respiratory equipment. The objective of this study was to determine whether SoClean® has potential as a disinfection device for families with CF by killing CF associated bacteria without altering nebulizer output. Ozone based disinfection effectively kills bacterial pathogens inoculated to home nebulizer equipment without gross changes in nebulizer function. Common bacterial pathogens associated with CF were inoculated onto the PariLC® jet nebulizer and bacterial recovery compared with or without varied ozone exposure. In separate experiments, nebulizer output was estimated after repeated ozone exposure by weighing the nebulizer. Ozone disinfection was time dependent with a 5 min infusion time and 120 min dwell time effectively killing >99.99% bacteria tested including Pseudomonas aeruginosa and Staphylococcus aureus. Over 250 h of repeat ozone exposure did not alter nebulizer output. This suggests SoClean® has potential as a user-friendly disinfection technique for home respiratory equipment. © 2018 Wiley Periodicals, Inc.

Fatal bacterial septicemia in a bottlenose dolphin Tursiops truncatus caused by Streptococcus iniae.

PubMed

Song, Zhiqi; Yue, Ruichao; Sun, Yanming; Liu, Chunfa; Khan, Sher Hayat; Li, Chaosi; Zhao, Ying; Zhou, Xiangmei; Yang, Lifeng; Zhao, Deming

2017-01-24

A captive 8 yr old male bottlenose dolphin Tursiops truncatus succumbed to septicemia with multisystemic inflammation including suppurative enteritis, encephalitis, and pneumonia with chronic pancreatitis. A pure culture of beta-hemolytic, catalase- and oxidase-negative, Gram-positive cocci was isolated from the hilar lymph nodes and pancreas. The isolate was identified by 16S rDNA sequencing as Streptococcus iniae. Histological examination of the digestive system revealed a mixed infection of both bacteria and fungus. Recognized as a pathogen in fish, dolphins, and humans, this is the first report of S. iniae in a dolphin in mainland China. As the number of managed animals in oceanariums is increasing, so is the frequency of contact with fish used as food for marine mammals and humans, highlighting the importance of education and appropriate personal protective protocols to minimize the risk of transmission. An understanding of marine mammal infectious disease organisms is essential to ensuring the health of marine mammals and humans coming into contact with such animals and their food. This study illustrates a systematic clinical, microbiological, and pathological investigation into a septicemic bottlenose dolphin infected with S. iniae. Our findings provide useful information for those involved in the diagnosis and control of infectious diseases in marine mammals and offer insight into an important zoonotic pathogen.

Elucidation of Bacterial Pneumonia-Causing Pathogens in Patients with Respiratory Viral Infection.

PubMed

Jung, Hwa Sik; Kang, Byung Ju; Ra, Seung Won; Seo, Kwang Won; Jegal, Yangjin; Jun, Jae Bum; Jung, Jiwon; Jeong, Joseph; Jeon, Hee Jeong; Ahn, Jae Sung; Lee, Taehoon; Ahn, Jong Joon

2017-10-01

Bacterial pneumonia occurring after respiratory viral infection is common. However, the predominant bacterial species causing pneumonia secondary to respiratory viral infections other than influenza remain unknown. The purpose of this study was to know whether the pathogens causing post-viral bacterial pneumonia vary according to the type of respiratory virus. Study subjects were 5,298 patients, who underwent multiplex real-time polymerase chain reaction for simultaneous detection of respiratory viruses, among who visited the emergency department or outpatient clinic with respiratory symptoms at Ulsan University Hospital between April 2013 and March 2016. The patients' medical records were retrospectively reviewed. A total of 251 clinically significant bacteria were identified in 233 patients with post-viral bacterial pneumonia. Mycoplasma pneumoniae was the most frequent bacterium in patients aged <16 years, regardless of the preceding virus type (p=0.630). In patients aged ≥16 years, the isolated bacteria varied according to the preceding virus type. The major results were as follows (p<0.001): pneumonia in patients with influenza virus (type A/B), rhinovirus, and human metapneumovirus infections was caused by similar bacteria, and the findings indicated that Staphylococcus aureus pneumonia was very common in these patients. In contrast, coronavirus, parainfluenza virus, and respiratory syncytial virus infections were associated with pneumonia caused by gram-negative bacteria. The pathogens causing post-viral bacterial pneumonia vary according to the type of preceding respiratory virus. This information could help in selecting empirical antibiotics in patients with post-viral pneumonia. Copyright©2017. The Korean Academy of Tuberculosis and Respiratory Diseases

Elucidation of Bacterial Pneumonia-Causing Pathogens in Patients with Respiratory Viral Infection

PubMed Central

Jung, Hwa Sik; Kang, Byung Ju; Ra, Seung Won; Seo, Kwang Won; Jegal, Yangjin; Jun, Jae-Bum; Jung, Jiwon; Jeong, Joseph; Jeon, Hee-Jeong; Ahn, Jae-Sung

2017-01-01

Background Bacterial pneumonia occurring after respiratory viral infection is common. However, the predominant bacterial species causing pneumonia secondary to respiratory viral infections other than influenza remain unknown. The purpose of this study was to know whether the pathogens causing post-viral bacterial pneumonia vary according to the type of respiratory virus. Methods Study subjects were 5,298 patients, who underwent multiplex real-time polymerase chain reaction for simultaneous detection of respiratory viruses, among who visited the emergency department or outpatient clinic with respiratory symptoms at Ulsan University Hospital between April 2013 and March 2016. The patients' medical records were retrospectively reviewed. Results A total of 251 clinically significant bacteria were identified in 233 patients with post-viral bacterial pneumonia. Mycoplasma pneumoniae was the most frequent bacterium in patients aged <16 years, regardless of the preceding virus type (p=0.630). In patients aged ≥16 years, the isolated bacteria varied according to the preceding virus type. The major results were as follows (p<0.001): pneumonia in patients with influenza virus (type A/B), rhinovirus, and human metapneumovirus infections was caused by similar bacteria, and the findings indicated that Staphylococcus aureus pneumonia was very common in these patients. In contrast, coronavirus, parainfluenza virus, and respiratory syncytial virus infections were associated with pneumonia caused by gram-negative bacteria. Conclusion The pathogens causing post-viral bacterial pneumonia vary according to the type of preceding respiratory virus. This information could help in selecting empirical antibiotics in patients with post-viral pneumonia. PMID:28905531

Bacterial infections after pediatric heart transplantation: Epidemiology, risk factors and outcomes.

PubMed

Rostad, Christina A; Wehrheim, Karla; Kirklin, James K; Naftel, David; Pruitt, Elizabeth; Hoffman, Timothy M; L'Ecuyer, Thomas; Berkowitz, Katie; Mahle, William T; Scheel, Janet N

2017-09-01

Bacterial infections represent a major cause of morbidity and mortality in heart transplant recipients. However, data describing the epidemiology and outcomes of these infections in children are limited. We analyzed the Pediatric Heart Transplant Study database of patients transplanted between 1993 and 2014 to determine the etiologies, risk factors and outcomes of children with bacterial infections post-heart transplantation. Of 4,458 primary transplants in the database, there were 4,815 infections that required hospitalization or intravenous therapy, 2,047 (42.51%) of which were bacterial. The risk of bacterial infection was highest in the first month post-transplant, and the bloodstream was the most common site (24.82%). In the early post-transplant period (<30 days post-transplant), coagulase-negative staphylococci were the most common pathogens (16.97%), followed by Enterobacter sp (11.99%) and Pseudomonas sp (11.62%). In the late post-transplant period, community-acquired pathogens Streptococcus pneumoniae (6.27%) and Haemophilus influenzae (2.82%) were also commonly identified. Patients' characteristics independently associated with acquisition of bacterial infection included younger age (p < 0.0001) and ventilator (p < 0.0001) or extracorporeal membrane oxygenation (p = 0.03) use at time of transplant. Overall mortality post-bacterial infection was 33.78%, and previous cardiac surgery (p < 0.001) and multiple sites of infection (p = 0.004) were independent predictors of death. Bacteria were the most common causes of severe infections in pediatric heart transplant recipients and were associated with high mortality rates. The risk of acquiring a bacterial infection was highest in the first month post-transplant, and a large proportion of the infections were caused by multidrug-resistant pathogens. Copyright © 2017 International Society for the Heart and Lung Transplantation. Published by Elsevier Inc. All rights reserved.

Identification of essential genes in Streptococcus pneumoniae by allelic replacement mutagenesis.

PubMed

Song, Jae-Hoon; Ko, Kwan Soo; Lee, Ji-Young; Baek, Jin Yang; Oh, Won Sup; Yoon, Ha Sik; Jeong, Jin-Yong; Chun, Jongsik

2005-06-30

To find potential targets of novel antimicrobial agents, we identified essential genes of Streptococcus pneumoniae using comparative genomics and allelic replacement mutagenesis. We compared the genome of S. pneumoniae R6 with those of Bacillus subtilis, Enterococcus faecalis, Escherichia coli, and Staphylococcus aureus, and selected 693 candidate target genes with > 40% amino acid sequence identity to the corresponding genes in at least two of the other species. The 693 genes were disrupted and 133 were found to be essential for growth. Of these, 32 encoded proteins of unknown function, and we were able to identify orthologues of 22 of these genes by genomic comparisons. The experimental method used in this study is easy to perform, rapid and efficient for identifying essential genes of bacterial pathogens.

[A novel TaqMan® MGB probe for specifically detecting Streptococcus mutans].

PubMed

Zheng, Hui; Lin, Jiu-Xiang; DU, Ning; Chen, Feng

2013-10-18

To design a new TaqMan® MGB probe for improving the specificity of Streptococcus mutans's detection. We extracted six DNA samples from different streptococcal strains for PCR reaction. Conventional nested PCR and TaqMan® MGB real-time PCR were applied independently. The first round of nested PCR was carried out with the bacterial universal primers, while a second PCR was conducted by using primers specific for the 16S rRNA gene of Streptococcus mutans. The TaqMan® MGB probe for Streptococcus mutans was designed from sequence analyses, and the primers were the same as nested PCR. Streptococcus mutans DNA with 2.5 mg/L was sequentially diluted at 5-fold intervals to 0.16 μg/L. Standard DNA samples were used to generate standard curves by TaqMan® MGB real-time PCR. In the nested PCR, the primers specific for Streptococcus mutans also detected Streptococcus gordonii with visible band of 282 bp, giving false-positive results. In the TaqMan® MGB real-time PCR reaction, only Streptococcus mutans was detected. The detection limitation of TaqMan® MGB real-time PCR for Streptococcus mutans 16S rRNA gene was 20 μg/L. We designed a new TaqMan® MGB probe, and successfully set up a PCR based method for detecting oral Streptococcus mutans. TaqMan® MGB real-time PCR is a both specific and sensitive bacterial detection method.

Effects of pathogen-specific clinical mastitis on probability of conception in Holstein dairy cows.

PubMed

Hertl, J A; Schukken, Y H; Welcome, F L; Tauer, L W; Gröhn, Y T

2014-11-01

The objective of this study was to estimate the effects of pathogen-specific clinical mastitis (CM), occurring in different weekly intervals before or after artificial insemination (AI), on the probability of conception in Holstein cows. Clinical mastitis occurring in weekly intervals from 6 wk before until 6 wk after AI was modeled. The first 4 AI in a cow's lactation were included. The following categories of pathogens were studied: Streptococcus spp. (comprising Streptococcus dysgalactiae, Streptococcus uberis, and other Streptococcus spp.); Staphylococcus aureus; coagulase-negative staphylococci (CNS); Escherichia coli; Klebsiella spp.; cases with CM signs but no bacterial growth (above the level that can be detected from our microbiological procedures) observed in the culture sample and cases with contamination (≥ 3 pathogens in the sample); and other pathogens [including Citrobacter, yeasts, Trueperella pyogenes, gram-negative bacilli (i.e., gram-negative organisms other than E. coli, Klebsiella spp., Enterobacter, and Citrobacter), Corynebacterium bovis, Corynebacterium spp., Pasteurella, Enterococcus, Pseudomonas, Mycoplasma, Prototheca, and others]. Other factors included in the model were parity (1, 2, 3, 4 and higher), season of AI (winter, spring, summer, autumn), day in lactation of first AI, farm, and other non-CM diseases (retained placenta, metritis, ketosis, displaced abomasum). Data from 90,271 AI in 39,361 lactations in 20,328 cows collected from 2003/2004 to 2011 from 5 New York State dairy farms were analyzed in a generalized linear mixed model with a Poisson distribution. The largest reductions in probability of conception were associated with CM occurring in the week before AI or in the 2 wk following AI. Escherichia coli and Klebsiella spp. had the greatest adverse effects on probability of conception. The probability of conception for a cow with any combination of characteristics may be calculated based on the parameter estimates. These

Bacterial-like PPP protein phosphatases: novel sequence alterations in pathogenic eukaryotes and peculiar features of bacterial sequence similarity.

PubMed

Kerk, David; Uhrig, R Glen; Moorhead, Greg B

2013-01-01

Reversible phosphorylation is a widespread modification affecting the great majority of eukaryotic cellular proteins, and whose effects influence nearly every cellular function. Protein phosphatases are increasingly recognized as exquisitely regulated contributors to these changes. The PPP (phosphoprotein phosphatase) family comprises enzymes, which catalyze dephosphorylation at serine and threonine residues. Nearly a decade ago, "bacterial-like" enzymes were recognized with similarity to proteins from various bacterial sources: SLPs (Shewanella-like phosphatases), RLPHs (Rhizobiales-like phosphatases), and ALPHs (ApaH-like phosphatases). A recent article from our laboratory appearing in Plant Physiology characterizes their extensive organismal distribution, abundance in plant species, predicted subcellular localization, motif organization, and sequence evolution. One salient observation is the distinct evolutionary trajectory followed by SLP genes and proteins in photosynthetic eukaryotes vs. animal and plant pathogens derived from photosynthetic ancestors. We present here a closer look at sequence data that emphasizes the distinctiveness of pathogen SLP proteins and that suggests that they might represent novel drug targets. A second observation in our original report was the high degree of similarity between the bacterial-like PPPs of eukaryotes and closely related proteins of the "eukaryotic-like" phyla Myxococcales and Planctomycetes. We here reflect on the possible implications of these observations and their importance for future research.

Group B Streptococcus Induces Neutrophil Recruitment to Gestational Tissues and Elaboration of Extracellular Traps and Nutritional Immunity.

PubMed

Kothary, Vishesh; Doster, Ryan S; Rogers, Lisa M; Kirk, Leslie A; Boyd, Kelli L; Romano-Keeler, Joann; Haley, Kathryn P; Manning, Shannon D; Aronoff, David M; Gaddy, Jennifer A

2017-01-01

Streptococcus agalactiae , or Group B Streptococcus (GBS), is a gram-positive bacterial pathogen associated with infection during pregnancy and is a major cause of morbidity and mortality in neonates. Infection of the extraplacental membranes surrounding the developing fetus, a condition known as chorioamnionitis, is characterized histopathologically by profound infiltration of polymorphonuclear cells (PMNs, neutrophils) and greatly increases the risk for preterm labor, stillbirth, or neonatal GBS infection. The advent of animal models of chorioamnionitis provides a powerful tool to study host-pathogen relationships in vivo and ex vivo . The purpose of this study was to evaluate the innate immune response elicited by GBS and evaluate how antimicrobial strategies elaborated by these innate immune cells affect bacteria. Our work using a mouse model of GBS ascending vaginal infection during pregnancy reveals that clinically isolated GBS has the capacity to invade reproductive tissues and elicit host immune responses including infiltration of PMNs within the choriodecidua and placenta during infection, mirroring the human condition. Upon interacting with GBS, murine neutrophils elaborate DNA-containing extracellular traps, which immobilize GBS and are studded with antimicrobial molecules including lactoferrin. Exposure of GBS to holo- or apo-forms of lactoferrin reveals that the iron-sequestration activity of lactoferrin represses GBS growth and viability in a dose-dependent manner. Together, these data indicate that the mouse model of ascending infection is a useful tool to recapitulate human models of GBS infection during pregnancy. Furthermore, this work reveals that neutrophil extracellular traps ensnare GBS and repress bacterial growth via deposition of antimicrobial molecules, which drive nutritional immunity via metal sequestration strategies.

Investigation of zoonotic disease pathogens (Aeromonas hydrophila, Pseudomonas fluorescens, Streptococcus iniae) seen in carp farms in the Northern Iraq-Erbil region by molecular methods

NASA Astrophysics Data System (ADS)

Ibraheem, Azad Saber; Önalan, Şükrü; Arabacı, Muhammed

2017-04-01

The aim of this study was to determine the zoonotic bacteria in carp farms in the Northern Iraq-Erbil region. Carp is the main fish species cultured in Erbil region. The most common zoonotic bacteria generally seen in carp farms are Aeromonas hydrophila, Pseudomonas fluorescens and Streptococcus iniae. Samples were collected from 25 carp farms in the Northern Iraq-Erbil region. Six carp samples were collected from each carp farm. Head kidney and intestine tissue samples were collected from each carp sample. Then head kidney and intestine tissue samples were pooled separately from each carp farm. Total bacterial DNA had been extracted from the 25 pooled head kidney and 25 intestinal tissue samples. The pathogen Primers were originally designed from 16S RNA gene region. Zoonotic bacteria were scanned in all tissue samples with absent/present analysis by RT-PCR. Furthermore, the capillary gel electrophoresis bands were used for confirmation of amplicon size which was planned during primer designing stage. As a result, thirteen carp farms were positive in the respect to Aeromonas hydrophila, eight carp farms were positive from head kidney and six carp farms were positive from the intestine, only one carp farm was positive from both head kidney and the intestine tissue samples. In the respect to Streptococcus iniae, four carp farms were positive from head kidney and two carp farms were positive from the intestine. Only one carp farm was positive in the respect to Pseudomonas fluorescens from the intestine. Totally, 9 of 25 carp farms were cleared (negative) the zoonotic bacteria. In conclusion, the zoonotic bacteria were high (64 %) in carp farms in the Northern Iraq-Erbil region.

Detection of bacterial pathogens including potential new species in human head lice from Mali.

PubMed

Amanzougaghene, Nadia; Fenollar, Florence; Sangaré, Abdoul Karim; Sissoko, Mahamadou S; Doumbo, Ogobara K; Raoult, Didier; Mediannikov, Oleg

2017-01-01

In poor African countries, where no medical and biological facilities are available, the identification of potential emerging pathogens of concern at an early stage is challenging. Head lice, Pediculus humanus capitis, have a short life, feed only on human blood and do not transmit pathogens to their progeny. They are, therefore, a perfect tool for the xenodiagnosis of current or recent human infection. This study assessed the occurrence of bacterial pathogens from head lice collected in two rural villages from Mali, where a high frequency of head lice infestation had previously been reported, using molecular methods. Results show that all 600 head lice, collected from 117 individuals, belonged to clade E, specific to West Africa. Bartonella quintana, the causative agent of trench fever, was identified in three of the 600 (0.5%) head lice studied. Our study also shows, for the first time, the presence of the DNA of two pathogenic bacteria, namely Coxiella burnetii (5.1%) and Rickettsia aeschlimannii (0.6%), detected in human head lice, as well as the DNA of potential new species from the Anaplasma and Ehrlichia genera of unknown pathogenicity. The finding of several Malian head lice infected with B. quintana, C. burnetii, R. aeschlimannii, Anaplasma and Ehrlichia is alarming and highlights the need for active survey programs to define the public health consequences of the detection of these emerging bacterial pathogens in human head lice.

Unraveling the Molecular Mechanisms Underlying the Nasopharyngeal Bacterial Community Structure.

PubMed

de Steenhuijsen Piters, Wouter A A; Bogaert, Debby

2016-02-02

The upper respiratory tract is colonized by a diverse array of commensal bacteria that harbor potential pathogens, such as Streptococcus pneumoniae. As long as the local microbial ecosystem-also called "microbiome"-is in balance, these potentially pathogenic bacterial residents cause no harm to the host. However, similar to macrobiological ecosystems, when the bacterial community structure gets perturbed, potential pathogens can overtake the niche and cause mild to severe infections. Recent studies using next-generation sequencing show that S. pneumoniae, as well as other potential pathogens, might be kept at bay by certain commensal bacteria, including Corynebacterium and Dolosigranulum spp. Bomar and colleagues are the first to explore a specific biological mechanism contributing to the antagonistic interaction between Corynebacterium accolens and S. pneumoniae in vitro [L. Bomar, S. D. Brugger, B. H. Yost, S. S. Davies, K. P. Lemon, mBio 7(1):e01725-15, 2016, doi:10.1128/mBio.01725-15]. The authors comprehensively show that C. accolens is capable of hydrolyzing host triacylglycerols into free fatty acids, which display antipneumococcal properties, suggesting that these bacteria might contribute to the containment of pneumococcus. This work exemplifies how molecular epidemiological findings can lay the foundation for mechanistic studies to elucidate the host-microbe and microbial interspecies interactions underlying the bacterial community structure. Next, translation of these results to an in vivo setting seems necessary to unveil the magnitude and importance of the observed effect in its natural, polymicrobial setting. Copyright © 2016 de Steenhuijsen Piters and Bogaert.

Unraveling the Molecular Mechanisms Underlying the Nasopharyngeal Bacterial Community Structure

PubMed Central

de Steenhuijsen Piters, Wouter A. A.

2016-01-01

ABSTRACT The upper respiratory tract is colonized by a diverse array of commensal bacteria that harbor potential pathogens, such as Streptococcus pneumoniae. As long as the local microbial ecosystem—also called “microbiome”—is in balance, these potentially pathogenic bacterial residents cause no harm to the host. However, similar to macrobiological ecosystems, when the bacterial community structure gets perturbed, potential pathogens can overtake the niche and cause mild to severe infections. Recent studies using next-generation sequencing show that S. pneumoniae, as well as other potential pathogens, might be kept at bay by certain commensal bacteria, including Corynebacterium and Dolosigranulum spp. Bomar and colleagues are the first to explore a specific biological mechanism contributing to the antagonistic interaction between Corynebacterium accolens and S. pneumoniae in vitro [L. Bomar, S. D. Brugger, B. H. Yost, S. S. Davies, K. P. Lemon, mBio 7(1):e01725-15, 2016, doi:10.1128/mBio.01725-15]. The authors comprehensively show that C. accolens is capable of hydrolyzing host triacylglycerols into free fatty acids, which display antipneumococcal properties, suggesting that these bacteria might contribute to the containment of pneumococcus. This work exemplifies how molecular epidemiological findings can lay the foundation for mechanistic studies to elucidate the host-microbe and microbial interspecies interactions underlying the bacterial community structure. Next, translation of these results to an in vivo setting seems necessary to unveil the magnitude and importance of the observed effect in its natural, polymicrobial setting. PMID:26838716

The Effect of a Low Fluoride Delivery System on Bacterial Metabolism.

DTIC Science & Technology

1980-09-01

Fluorides, an4 -Ique mechanisms, slow release delivery, temporary restora- tions, bacterial attachment, Streptococcus mutans , bacterial metabo’ilsm...concentrations of NaF, SnF 4 , Na2SnF6 , TiF 4 , and SnCI2 on altering plaque formation by Streptococcus mutans NCTC 10449. Specific tests were...preparation. Microorganisms, Growth Media, and Growth A streptomycin resistant mutant of Streptococcus mutans NCTC 10449 (Bratthall serotype c) has been

Quorum sensing and Bacterial Pathogenicity: From Molecules to Disease

PubMed Central

Deep, Antariksh; Chaudhary, Uma; Gupta, Varsha

2011-01-01

Quorum sensing in prokaryotic biology refers to the ability of a bacterium to sense information from other cells in the population when they reach a critical concentration (i.e. a Quorum) and communicate with them. The “language” used for this intercellular communication is based on small, self-generated signal molecules called as autoinducers. Quorum sensing is thought to afford pathogenic bacteriaa mechanism to minimize host immune responses by delaying theproduction of tissue-damaging virulence factors until sufficientbacteria have amassed and are prepared to overwhelm host defensemechanisms and establish infection. Quorum sensing systems are studied in a large number of gram-negative bacterial species belonging to α, β, and γ subclasses of proteobacteria. Among the pathogenic bacteria, Pseudomonas aeruginosa is perhaps the best understood in terms of the virulence factors regulated and the role the Quorum sensing plays in pathogenicity. Presently, Quorum sensing is considered as a potential novel target for antimicrobial therapy to control multi/all drug-resistant infections. This paper reviews Quorum sensing in gram positive and gram negative bacteria and its role in biofilm formation. PMID:21701655

Activity of Genital Tract Secretions and Synthetic Antimicrobial Peptides against Group B Streptococcus.

PubMed

Agarwal, Nidhi; Buckley, Niall; Nakra, Natasha; Gialanella, Philip; Yuan, Weirong; Ghartey, Jeny P

2015-12-01

Genital tract secretions inhibit Escherichia coli (E. coli) through antimicrobial peptides (AMP) secreted by the host and vaginal microbiota. However, there are limited data against group B Streptococcus (GBS). Group B Streptococcus were incubated with cervico-vaginal lavage (CVL) samples from healthy non-pregnant women (n = 12) or synthetic AMP and monitored for bacterial growth using a turbidimetric approach. E. coli inhibitory activity was determined by a colony-forming unit assay. None of the CVL samples inhibited GBS. The human neutrophil peptide-1 and human defensin 5 inhibited GBS growth by ≥80% at concentrations ≥20 μg/mL and ≥50 μg/mL, respectively, while human beta-defensin 2 and LL-37 did not inhibit at highest concentration tested (100 μg/mL). In contrast, all AMP inhibited E. coli. Antimicrobial peptides may protect against E. coli colonization but have more limited activity against GBS. Future studies will focus on augmenting host defense with specific AMP to prevent genitourinary infection with these pathogenic organisms. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Lactobacillus plantarum lipoteichoic acid inhibits biofilm formation of Streptococcus mutans

PubMed Central

Ahn, Ki Bum; Baik, Jung Eun; Park, Ok-Jin; Yun, Cheol-Heui

2018-01-01

Dental caries is a biofilm-dependent oral disease and Streptococcus mutans is the known primary etiologic agent of dental caries that initiates biofilm formation on tooth surfaces. Although some Lactobacillus strains inhibit biofilm formation of oral pathogenic bacteria, the molecular mechanisms by which lactobacilli inhibit bacterial biofilm formation are not clearly understood. In this study, we demonstrated that Lactobacillus plantarum lipoteichoic acid (Lp.LTA) inhibited the biofilm formation of S. mutans on polystyrene plates, hydroxyapatite discs, and dentin slices without affecting the bacterial growth. Lp.LTA interferes with sucrose decomposition of S. mutans required for the production of exopolysaccharide, which is a main component of biofilm. Lp.LTA also attenuated the biding of fluorescein isothiocyanate-conjugated dextran to S. mutans, which is known to have a high affinity to exopolysaccharide on S. mutans. Dealanylated Lp.LTA did not inhibit biofilm formation of S. mutans implying that D-alanine moieties in the Lp.LTA structure were crucial for inhibition. Collectively, these results suggest that Lp.LTA attenuates S. mutans biofilm formation and could be used to develop effective anticaries agents. PMID:29420616

Comparative analysis of prophages in Streptococcus mutans genomes

PubMed Central

Fu, Tiwei; Fan, Xiangyu; Long, Quanxin; Deng, Wanyan; Song, Jinlin

2017-01-01

Prophages have been considered genetic units that have an intimate association with novel phenotypic properties of bacterial hosts, such as pathogenicity and genomic variation. Little is known about the genetic information of prophages in the genome of Streptococcus mutans, a major pathogen of human dental caries. In this study, we identified 35 prophage-like elements in S. mutans genomes and performed a comparative genomic analysis. Comparative genomic and phylogenetic analyses of prophage sequences revealed that the prophages could be classified into three main large clusters: Cluster A, Cluster B, and Cluster C. The S. mutans prophages in each cluster were compared. The genomic sequences of phismuN66-1, phismuNLML9-1, and phismu24-1 all shared similarities with the previously reported S. mutans phages M102, M102AD, and ϕAPCM01. The genomes were organized into seven major gene clusters according to the putative functions of the predicted open reading frames: packaging and structural modules, integrase, host lysis modules, DNA replication/recombination modules, transcriptional regulatory modules, other protein modules, and hypothetical protein modules. Moreover, an integrase gene was only identified in phismuNLML9-1 prophages. PMID:29158986

Gene expression platform for synthetic biology in the human pathogen Streptococcus pneumoniae.

PubMed

Sorg, Robin A; Kuipers, Oscar P; Veening, Jan-Willem

2015-03-20

The human pathogen Streptococcus pneumoniae (pneumococcus) is a bacterium that owes its success to complex gene expression regulation patterns on both the cellular and the population level. Expression of virulence factors enables a mostly hazard-free presence of the commensal, in balance with the host and niche competitors. Under specific circumstances, changes in this expression can result in a more aggressive behavior and the reversion to the invasive form as pathogen. These triggering conditions are very difficult to study due to the fact that environmental cues are often unknown or barely possible to simulate outside the host (in vitro). An alternative way of investigating expression patterns is found in synthetic biology approaches of reconstructing regulatory networks that mimic an observed behavior with orthogonal components. Here, we created a genetic platform suitable for synthetic biology approaches in S. pneumoniae and characterized a set of standardized promoters and reporters. We show that our system allows for fast and easy cloning with the BglBrick system and that reliable and robust gene expression after integration into the S. pneumoniae genome is achieved. In addition, the cloning system was extended to allow for direct linker-based assembly of ribosome binding sites, peptide tags, and fusion proteins, and we called this new generally applicable standard "BglFusion". The gene expression platform and the methods described in this study pave the way for employing synthetic biology approaches in S. pneumoniae.

Lung abscess due to Streptococcus pneumoniae: a case series and brief review of the literature.

PubMed

Nicolini, Antonello; Cilloniz, Catia; Senarega, Renata; Ferraioli, Gianluca; Barlascini, Cornelius

2014-01-01

Anaerobes used to be the most common cause of community-acquired lung abscess, and Streptococcus species used to be the second most common cause. In recent years, this has been changing. Klebsiella pneumoniae is now an increasing cause of community- acquired lung abscess, but Streptococcus species continue to be major pathogens. Necrotizing pneumonia has generally been regarded as a rare complication of pneumococcal infection in adults. Type 3 Streptococcus pneumoniae was the single most common type implicated in necrosis; however, many other serotypes were implicated. This entity predominately infects children, but is present also in adults. Lung abscess in adults due to Streptococcus pneumoniae is not common. In this regard we present a case series of pulmonary cavitation due to Streptococcus pneumoniae and discuss the possible pathogenic mechanism of the disease.

Recent Developments in Copper and Zinc Homeostasis in Bacterial Pathogens

PubMed Central

Braymer, Joseph J.; Giedroc, David P.

2014-01-01

Copper and zinc homeostasis systems in pathogenic bacteria are required to resist host efforts to manipulate the availability and toxicity of these metal ions. Central to this microbial adaptive response is the involvement of metal-trafficking and -sensing proteins that ultimately exercise control of metal speciation in the cell. Cu- and Zn-specific metalloregulatory proteins regulate the transcription of metal-responsive genes while metallochaperones and related proteins ensure that these metals are appropriately buffered by the intracellular milieu and delivered to correct intracellular targets. In this review, we summarize recent findings on how bacterial pathogens mount a metal-specific response to derail host efforts to win the “fight over metals.” PMID:24463765

Multilocus analysis of extracellular putative virulence proteins made by group A Streptococcus: population genetics, human serologic response, and gene transcription.

PubMed

Reid, S D; Green, N M; Buss, J K; Lei, B; Musser, J M

2001-06-19

Species of pathogenic microbes are composed of an array of evolutionarily distinct chromosomal genotypes characterized by diversity in gene content and sequence (allelic variation). The occurrence of substantial genetic diversity has hindered progress in developing a comprehensive understanding of the molecular basis of virulence and new therapeutics such as vaccines. To provide new information that bears on these issues, 11 genes encoding extracellular proteins in the human bacterial pathogen group A Streptococcus identified by analysis of four genomes were studied. Eight of the 11 genes encode proteins with a LPXTG(L) motif that covalently links Gram-positive virulence factors to the bacterial cell surface. Sequence analysis of the 11 genes in 37 geographically and phylogenetically diverse group A Streptococcus strains cultured from patients with different infection types found that recent horizontal gene transfer has contributed substantially to chromosomal diversity. Regions of the inferred proteins likely to interact with the host were identified by molecular population genetic analysis, and Western immunoblot analysis with sera from infected patients confirmed that they were antigenic. Real-time reverse transcriptase-PCR (TaqMan) assays found that transcription of six of the 11 genes was substantially up-regulated in the stationary phase. In addition, transcription of many genes was influenced by the covR and mga trans-acting gene regulatory loci. Multilocus investigation of putative virulence genes by the integrated approach described herein provides an important strategy to aid microbial pathogenesis research and rapidly identify new targets for therapeutics research.

Genome specialization and decay of the strangles pathogen, Streptococcus equi, is driven by persistent infection

PubMed Central

Harris, Simon R.; Robinson, Carl; Steward, Karen F.; Webb, Katy S.; Paillot, Romain; Parkhill, Julian; Holden, Matthew T.G.; Waller, Andrew S.

2015-01-01

Strangles, the most frequently diagnosed infectious disease of horses worldwide, is caused by Streptococcus equi. Despite its prevalence, the global diversity and mechanisms underlying the evolution of S. equi as a host-restricted pathogen remain poorly understood. Here, we define the global population structure of this important pathogen and reveal a population replacement in the late 19th or early 20th Century. Our data reveal a dynamic genome that continues to mutate and decay, but also to amplify and acquire genes despite the organism having lost its natural competence and become host-restricted. The lifestyle of S. equi within the horse is defined by short-term acute disease, strangles, followed by long-term infection. Population analysis reveals evidence of convergent evolution in isolates from post-acute disease samples as a result of niche adaptation to persistent infection within a host. Mutations that lead to metabolic streamlining and the loss of virulence determinants are more frequently found in persistent isolates, suggesting that the pathogenic potential of S. equi reduces as a consequence of long-term residency within the horse post-acute disease. An example of this is the deletion of the equibactin siderophore locus that is associated with iron acquisition, which occurs exclusively in persistent isolates, and renders S. equi significantly less able to cause acute disease in the natural host. We identify several loci that may similarly be required for the full virulence of S. equi, directing future research toward the development of new vaccines against this host-restricted pathogen. PMID:26160165

Estimation of decay rates for fecal indicator bacteria and bacterial pathogens in agricultural field-applied manure

EPA Science Inventory

Field-applied manure is an important source of pathogenic exposure in surface water bodies for humans and ecological receptors. We analyzed the persistence and decay of fecal indicator bacteria and bacterial pathogens from three sources (cattle, poultry, swine) for agricultural f...

Leukocyte populations and cytokine expression in the mammary gland in a mouse model of Streptococcus agalactiae mastitis.

PubMed

Trigo, Gabriela; Dinis, Márcia; França, Angela; Bonifácio Andrade, Elva; Gil da Costa, Rui M; Ferreira, Paula; Tavares, Delfina

2009-07-01

Streptococcus agalactiae is a contagious, mastitis-causing pathogen that is highly adapted to survive in the bovine mammary gland. This study used a BALB/c mouse model of Streptococcus agalactiae mastitis to evaluate leukocyte populations in regional lymph nodes and cytokine expression in the mammary gland involved in the immune response against Streptococcus agalactiae. It was found that the bacteria replicated efficiently in the mammary gland, peaking after 24 h and increasing by 100-fold. Dissemination of bacteria to systemic organs was observed 6 h after infection. At the same time, a massive infiltration of polymorphonuclear cells and an increase in the inflammatory cytokines interleukin (IL)-1beta, IL-6 and tumour necrosis factor-alpha were detected in mammary glands, indicating an early inflammatory response. A decrease in the levels of inflammatory cytokines in mammary glands was observed 72 h after infection, accompanied by an increase in the levels of IL-12 and IL-10, which were related to a gradual decrease in bacterial load. An increase in the number of macrophages and B220(+) lymphocytes and similar increases in both CD4(+) and CD8(+) T cells in regional lymph nodes were observed, being most pronounced 5 days after infection. Moreover, increased levels of anti-Streptococcus agalactiae antibodies in the mammary gland were observed 10 days after infection. Overall, these data suggest that the host exhibits both innate and acquired immune responses in response to Streptococcus agalactiae mastitis.

Application of a Bacteriophage Lysin To Disrupt Biofilms Formed by the Animal Pathogen Streptococcus suis ▿ †

PubMed Central

Meng, Xiangpeng; Shi, Yibo; Ji, Wenhui; Meng, Xueling; Zhang, Jing; Wang, Hengan; Lu, Chengping; Sun, Jianhe; Yan, Yaxian

2011-01-01

Bacterial biofilms are crucial to the pathogenesis of many important infections and are difficult to eradicate. Streptococcus suis is an important pathogen of pigs, and here the biofilm-forming ability of 32 strains of this species was determined. Significant biofilms were completely formed by 10 of the strains after 60 h of incubation, with exopolysaccharide production in the biofilm significantly higher than that in the corresponding planktonic cultures. S. suis strain SS2-4 formed a dense biofilm, as revealed by scanning electron microscopy, and in this state exhibited increased resistance to a number of antibiotics (ampicillin, amoxicillin, ciprofloxacin, kanamycin, and rifampin) compared to that of planktonic cultures. A bacteriophage lysin, designated LySMP, was used to attack biofilms alone and in combination with antibiotics and bacteriophage. The results demonstrated that the biofilms formed by S. suis, especially strains SS2-4 and SS2-H, could be dispersed by LySMP and with >80% removal compared to a biofilm reduction by treatment with either antibiotics or bacteriophage alone of less than 20%; in addition to disruption of the biofilm structure, the S. suis cells themselves were inactivated by LySMP. The efficacy of LySMP was not dose dependent, and in combination with antibiotics, it acted synergistically to maximize dispersal of the S. suis biofilm and inactivate the released cells. These data suggest that bacteriophage lysin could form part of an effective strategy to treat S. suis infections and represents a new class of antibiofilm agents. PMID:21984241

Defense reactions of bean genotypes to bacterial pathogens in controlled conditions

NASA Astrophysics Data System (ADS)

Uysal, B.; Bastas, K. K.

2018-03-01

This study was focused on the role of antioxidant enzymes and total protein in imparting resistance against common bacterial blight caused by Xanthomonas axonopodis pv. phaseoli (Xap) and halo blight caused by Pseudomonas syringae pv. phaseolicola (Psp) in bean. Activities of Ascorbate peroxidase (APX), Catalase (CAT) and total protein were studied in resistant and susceptible bean genotypes. Five-day-old seedlings were inoculated with a bacterial suspension (108 CFU ml-1) and harvested at different time intervals (0, 12, 24 and 36 up to 72 h) under controlled growing conditions and assayed for antioxidant enzymes and total protein. Temporal increase of CAT, APX enzymes activities showed maximum activity at 12 h after both pathogens inoculation (hpi) in resistant cultivar, whereas in susceptible it increased at 72 h after both pathogens inoculation for CAT and 12, 24 h for APX enzymes. Maximum total protein activities were observed at 12 h and 24 h respectively after Xap, Psp inoculation (hpi) in resistant and maximum activities were observed at 24 h and 72 h respectively after Xap, Psp inoculation (hpi) in susceptible. Increase of antioxidant enzyme and total protein activities might be an important component in the defense strategy of resistance and susceptible bean genotypes against the bacterial infection. These findings suggest that disease protection is proportional to the amount of enhanced CAT, APX enzyme and total protein activity.

An Overview of the Control of Bacterial Pathogens in Cattle Manure

PubMed Central

Manyi-Loh, Christy E.; Mamphweli, Sampson N.; Meyer, Edson L.; Makaka, Golden; Simon, Michael; Okoh, Anthony I.

2016-01-01

Cattle manure harbors microbial constituents that make it a potential source of pollution in the environment and infections in humans. Knowledge of, and microbial assessment of, manure is crucial in a bid to prevent public health and environmental hazards through the development of better management practices and policies that should govern manure handling. Physical, chemical and biological methods to reduce pathogen population in manure do exist, but are faced with challenges such as cost, odor pollution, green house gas emission, etc. Consequently, anaerobic digestion of animal manure is currently one of the most widely used treatment method that can help to salvage the above-mentioned adverse effects and in addition, produces biogas that can serve as an alternative/complementary source of energy. However, this method has to be monitored closely as it could be fraught with challenges during operation, caused by the inherent characteristics of the manure. In addition, to further reduce bacterial pathogens to a significant level, anaerobic digestion can be combined with other methods such as thermal, aerobic and physical methods. In this paper, we review the bacterial composition of cattle manure as well as methods engaged in the control of pathogenic microbes present in manure and recommendations that need to be respected and implemented in order to prevent microbial contamination of the environment, animals and humans. PMID:27571092

The Regulatory Small RNA MarS Supports Virulence of Streptococcus pyogenes.

PubMed

Pappesch, Roberto; Warnke, Philipp; Mikkat, Stefan; Normann, Jana; Wisniewska-Kucper, Aleksandra; Huschka, Franziska; Wittmann, Maja; Khani, Afsaneh; Schwengers, Oliver; Oehmcke-Hecht, Sonja; Hain, Torsten; Kreikemeyer, Bernd; Patenge, Nadja

2017-09-25

Small regulatory RNAs (sRNAs) play a role in the control of bacterial virulence gene expression. In this study, we investigated an sRNA that was identified in Streptococcus pyogenes (group A Streptococcus, GAS) but is conserved throughout various streptococci. In a deletion strain, expression of mga, the gene encoding the multiple virulence gene regulator, was reduced. Accordingly, transcript and proteome analyses revealed decreased expression of several Mga-activated genes. Therefore, and because the sRNA was shown to interact with the 5' UTR of the mga transcript in a gel-shift assay, we designated it MarS for m ga-activating regulatory sRNA. Down-regulation of important virulence factors, including the antiphagocytic M-protein, led to increased susceptibility of the deletion strain to phagocytosis and reduced adherence to human keratinocytes. In a mouse infection model, the marS deletion mutant showed reduced dissemination to the liver, kidney, and spleen. Additionally, deletion of marS led to increased tolerance towards oxidative stress. Our in vitro and in vivo results indicate a modulating effect of MarS on virulence gene expression and on the pathogenic potential of GAS.

Transmission probabilities and durations of immunity for three pathogenic group B Streptococcus serotypes

PubMed Central

Percha, Bethany; Newman, M. E. J.; Foxman, Betsy

2012-01-01

Group B Streptococcus (GBS) remains a major cause of neonatal sepsis and is an emerging cause of invasive bacterial infections. The 9 known serotypes vary in virulence, and there is little cross-immunity. Key parameters for planning an effective vaccination strategy, such as average length of immunity and transmission probabilities by serotype, are unknown. We simulated GBS spread in a population using a computational model with parameters derived from studies of GBS sexual transmission in a college dormitory. Here we provide estimates of the duration of immunity relative to the transmission probabilities for the 3 GBS serotypes most associated with invasive disease: Ia, III, and V. We also place upper limits on the durations of immunity for serotype Ia (570 days), III (1125 days) and V (260 days). Better transmission estimates are required to establish the epidemiological parameters of GBS infection and determine the best vaccination strategies to prevent GBS disease. PMID:21605704

Survival of the Fittest: How Bacterial Pathogens Utilize Bile To Enhance Infection

PubMed Central

Sistrunk, Jeticia R.; Nickerson, Kourtney P.; Chanin, Rachael B.; Rasko, David A.

2016-01-01

SUMMARY Bacterial pathogens have coevolved with humans in order to efficiently infect, replicate within, and be transmitted to new hosts to ensure survival and a continual infection cycle. For enteric pathogens, the ability to adapt to numerous host factors under the harsh conditions of the gastrointestinal tract is critical for establishing infection. One such host factor readily encountered by enteric bacteria is bile, an innately antimicrobial detergent-like compound essential for digestion and nutrient absorption. Not only have enteric pathogens evolved to resist the bactericidal conditions of bile, but these bacteria also utilize bile as a signal to enhance virulence regulation for efficient infection. This review provides a comprehensive and up-to-date analysis of bile-related research with enteric pathogens. From common responses to the unique expression of specific virulence factors, each pathogen has overcome significant challenges to establish infection in the gastrointestinal tract. Utilization of bile as a signal to modulate virulence factor expression has led to important insights for our understanding of virulence mechanisms for many pathogens. Further research on enteric pathogens exposed to this in vivo signal will benefit therapeutic and vaccine development and ultimately enhance our success at combating such elite pathogens. PMID:27464994

Analytical specificity and sensitivity of a real-time polymerase chain reaction assay for identification of bovine mastitis pathogens.

PubMed

Koskinen, M T; Holopainen, J; Pyörälä, S; Bredbacka, P; Pitkälä, A; Barkema, H W; Bexiga, R; Roberson, J; Sølverød, L; Piccinini, R; Kelton, D; Lehmusto, H; Niskala, S; Salmikivi, L

2009-03-01

Intramammary infection (IMI), also known as mastitis, is the most frequently occurring and economically the most important infectious disease in dairy cattle. This study provides a validation of the analytical specificity and sensitivity of a real-time PCR-based assay that identifies 11 major pathogen species or species groups responsible for IMI, and a gene coding for staphylococcal beta-lactamase production (penicillin resistance). Altogether, 643 culture isolates originating from clinical bovine mastitis, human, and companion animal samples were analyzed using the assay. The isolates represented 83 different species, groups, or families, and originated from 6 countries in Europe and North America. The analytical specificity and sensitivity of the assay was 100% in bacterial and beta-lactamase identification across all isolates originating from bovine mastitis (n = 454). When considering the entire culture collection (including also the isolates originating from human and companion animal samples), 4 Streptococcus pyogenes, 1 Streptococcus salivarius, and 1 Streptococcus sanguis strain of human origin were identified as Streptococcus uberis, and 3 Shigella spp. strains were identified as Escherichia coli, decreasing specificity to 99% in Strep. uberis and to 99.5% in E. coli. These false-positive results were confirmed by sequencing of the 16S rRNA gene. Specificity and sensitivity remained at 100% for all other bacterial targets across the entire culture collection. In conclusion, the real-time PCR assay shows excellent analytical accuracy and holds much promise for use in routine bovine IMI testing programs. This study provides the basis for evaluating the assay's diagnostic performance against the conventional bacterial culture method in clinical field trials using mastitis milk samples.

Increased Pilus Production Conferred by a Naturally Occurring Mutation Alters Host-Pathogen Interaction in Favor of Carriage in Streptococcus pyogenes

PubMed Central

Olsen, Randall J.; Cantu, Concepcion; Pallister, Kyler B.; Guerra, Fermin E.; Voyich, Jovanka M.; Musser, James M.

2017-01-01

ABSTRACT Studies of the human pathogen group A Streptococcus (GAS) define the carrier phenotype to be an increased ability to adhere to and persist on epithelial surfaces and a decreased ability to cause disease. We tested the hypothesis that a single amino acid change (Arg135Gly) in a highly conserved sensor kinase (LiaS) of a poorly defined GAS regulatory system contributes to a carrier phenotype through increased pilus production. When introduced into an emm serotype-matched invasive strain, the carrier allele (the gene encoding the LiaS protein with an arginine-to-glycine change at position 135 [liaSR135G]) recapitulated a carrier phenotype defined by an increased ability to adhere to mucosal surfaces and a decreased ability to cause disease. Gene transcript analyses revealed that the liaS mutation significantly altered transcription of the genes encoding pilus in the presence of bacitracin. Elimination of pilus production in the isogenic carrier mutant decreased its ability to colonize the mouse nasopharynx and to adhere to and be internalized by cultured human epithelial cells and restored the virulence phenotype in a mouse model of necrotizing fasciitis. We also observed significantly reduced survival of the isogenic carrier mutant compared to that of the parental invasive strain after exposure to human neutrophils. Elimination of pilus in the isogenic carrier mutant increased the level of survival after exposure to human neutrophils to that for the parental invasive strain. Together, our data demonstrate that the carrier mutation (liaSR135G) affects pilus expression. Our data suggest new mechanisms of pilus gene regulation in GAS and that the invasiveness associated with pilus gene regulation in GAS differs from the enhanced invasiveness associated with increased pilus production in other bacterial pathogens. PMID:28264907

Population structure of Streptococcus oralis

PubMed Central

Do, Thuy; Jolley, Keith A.; Maiden, Martin C. J.; Gilbert, Steven C.; Clark, Douglas; Wade, William G.; Beighton, David

2009-01-01

Streptococcus oralis is a member of the normal human oral microbiota, capable of opportunistic pathogenicity; like related oral streptococci, it exhibits appreciable phenotypic and genetic variation. A multilocus sequence typing (MLST) scheme for S. oralis was developed and the resultant data analysed to examine the population structure of the species. Analysis of 113 isolates, confirmed as belonging to the S. oralis/mitis group by 16S rRNA gene sequencing, characterized the population as highly diverse and undergoing inter- and intra-species recombination with a probable clonal complex structure. ClonalFrame analysis of these S. oralis isolates along with examples of Streptococcus pneumoniae, Streptococcus mitis and Streptococcus pseudopneumoniae grouped the named species into distinct, coherent populations and did not support the clustering of S. pseudopneumoniae with S. mitis as reported previously using distance-based methods. Analysis of the individual loci suggested that this discrepancy was due to the possible hybrid nature of S. pseudopneumoniae. The data are available on the public MLST website (http://pubmlst.org/soralis/). PMID:19423627

Comprehensive Analysis of Bacterial Flora in Postoperative Maxillary Cyst Fluid by 16S rRNA Gene and Culture Methods

PubMed Central

Sano, Naoto; Yamashita, Yoshio; Fukuda, Kazumasa; Taniguchi, Hatsumi; Goto, Masaaki; Miyamoto, Hiroshi

2012-01-01

Intracystic fluid was aseptically collected from 11 patients with postoperative maxillary cyst (POMC), and DNA was extracted from the POMC fluid. Bacterial species were identified by sequencing after cloning of approximately 580 bp of the 16S rRNA gene. Identification of pathogenic bacteria was also performed by culture methods. The phylogenetic identity was determined by sequencing 517–596 bp in each of the 1139 16S rRNA gene clones. A total of 1114 clones were classified while the remaining 25 clones were unclassified. A total of 103 bacterial species belonging to 42 genera were identified in POMC fluid samples by 16S rRNA gene analysis. Species of Prevotella (91%), Neisseria (73%), Fusobacterium (73%), Porphyromonas (73%), and Propionibacterium (73%) were found to be highly prevalent in all patients. Streptococcus mitis (64%), Fusobacterium nucleatum (55%), Propionibacterium acnes (55%), Staphylococcus capitis (55%), and Streptococcus salivarius (55%) were detected in more than 6 of the 11 patients. The results obtained by the culture method were different from those obtained by 16S rRNA gene analysis, but both approaches may be necessary for the identification of pathogens, especially of bacteria that are difficult to detect by culture methods, and the development of rational treatments for patients with POMC. PMID:22685668

Streptococcal toxic shock syndrome caused by Streptococcus suis serotype 2.

PubMed

Tang, Jiaqi; Wang, Changjun; Feng, Youjun; Yang, Weizhong; Song, Huaidong; Chen, Zhihai; Yu, Hongjie; Pan, Xiuzhen; Zhou, Xiaojun; Wang, Huaru; Wu, Bo; Wang, Haili; Zhao, Huamei; Lin, Ying; Yue, Jianhua; Wu, Zhenqiang; He, Xiaowei; Gao, Feng; Khan, Abdul Hamid; Wang, Jian; Zhao, Guo-Ping; Wang, Yu; Wang, Xiaoning; Chen, Zhu; Gao, George F

2006-05-01

Streptococcus suis serotype 2 (S. suis 2, SS2) is a major zoonotic pathogen that causes only sporadic cases of meningitis and sepsis in humans. Most if not all cases of Streptococcal toxic shock syndrome (STSS) that have been well-documented to date were associated with the non-SS2 group A streptococcus (GAS). However, a recent large-scale outbreak of SS2 in Sichuan Province, China, appeared to be caused by more invasive deep-tissue infection with STSS, characterized by acute high fever, vascular collapse, hypotension, shock, and multiple organ failure. We investigated this outbreak of SS2 infections in both human and pigs, which took place from July to August, 2005, through clinical observation and laboratory experiments. Clinical and pathological characterization of the human patients revealed the hallmarks of typical STSS, which to date had only been associated with GAS infection. Retrospectively, we found that this outbreak was very similar to an earlier outbreak in Jiangsu Province, China, in 1998. We isolated and analyzed 37 bacterial strains from human specimens and eight from pig specimens of the recent outbreak, as well as three human isolates and two pig isolates from the 1998 outbreak we had kept in our laboratory. The bacterial isolates were examined using light microscopy observation, pig infection experiments, multiplex-PCR assay, as well as restriction fragment length polymorphisms (RFLP) and multiple sequence alignment analyses. Multiple lines of evidence confirmed that highly virulent strains of SS2 were the causative agents of both outbreaks. We report, to our knowledge for the first time, two outbreaks of STSS caused by SS2, a non-GAS streptococcus. The 2005 outbreak was associated with 38 deaths out of 204 documented human cases; the 1998 outbreak with 14 deaths out of 25 reported human cases. Most of the fatal cases were characterized by STSS; some of them by meningitis or severe septicemia. The molecular mechanisms underlying these human STSS

Selective propensity of bovine jugular vein material to bacterial adhesions: An in-vitro study.

PubMed

Jalal, Zakaria; Galmiche, Louise; Lebeaux, David; Villemain, Olivier; Brugada, Georgia; Patel, Mehul; Ghigo, Jean-Marc; Beloin, Christophe; Boudjemline, Younes

2015-11-01

Percutaneous pulmonary valve implantation (PPVI) using Melody valve made of bovine jugular vein is safe and effective. However, infective endocarditis has been reported for unclear reasons. We sought to assess the impact of valvular substrates on selective bacterial adhesion. Three valved stents (Melody valve, homemade stents with bovine and porcine pericardium) were tested in-vitro for bacterial adhesion using Staphylococcus aureus and Streptococcus sanguinis strains. Bacterial adhesion was higher on bovine jugular venous wall for S. aureus and on Melody valvular leaflets for S. sanguinis in control groups and significantly increased in traumatized Melody valvular leaflets with both bacteria (traumatized vs non traumatized: p=0.05). Bacterial adhesion was lower on bovine pericardial leaflets. Selective adhesion of S. aureus and S. sanguinis pathogenic strains to Melody valve tissue was noted on healthy tissue and increased after implantation procedural steps. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Secondary Bacterial Infections Associated with Influenza Pandemics

PubMed Central

Morris, Denise E.; Cleary, David W.; Clarke, Stuart C.

2017-01-01

Lower and upper respiratory infections are the fourth highest cause of global mortality (Lozano et al., 2012). Epidemic and pandemic outbreaks of respiratory infection are a major medical concern, often causing considerable disease and a high death toll, typically over a relatively short period of time. Influenza is a major cause of epidemic and pandemic infection. Bacterial co/secondary infection further increases morbidity and mortality of influenza infection, with Streptococcus pneumoniae, Haemophilus influenzae, and Staphylococcus aureus reported as the most common causes. With increased antibiotic resistance and vaccine evasion it is important to monitor the epidemiology of pathogens in circulation to inform clinical treatment and development, particularly in the setting of an influenza epidemic/pandemic. PMID:28690590

Isolation of Streptococcus agalactiae and an aquatic birnavirus from doctor fish Garra rufa L

PubMed Central

2013-01-01

Background The doctor fish, Garra rufa, has become increasingly popular as a treatment for skin disorders and for pedicures in recent years. Despite this there is very little information available regarding the welfare of these fish and the range of potential pathogens they may carry. In this study, a group of fish suffering from post-transport mortalities were examined and the isolated pathogens identified. Findings Group B Streptococcus agalactiae was isolated from kidney swabs of the fish and found to be resistant to a number of antibiotics. In addition to this, a fish virus belonging to the aquabirnavirus group, serogroup C was isolated for the first time in Ireland. However, no clinical signs of disease typical of bacterial or viral infections were observed in any fish examined. Conclusions As no clinical signs of disease attributable to either of the pathogens identified were found it was concluded that the mortalities were most likely due to transport related stress exacerbated by the presence of the pathogens. Further work is required to assess the suitability of current transport strategies and to examine the potential risk associated with the transport of live ornamental fish. PMID:24028334

STREPTOCOCCUS: A WORLDWIDE FISH HEALTH PROBLEM

USDA-ARS?s Scientific Manuscript database

Streptococcus iniae and S. agalactiae are important emergent pathogens that affect many fish species worldwide, especially in warm-water regions. In marine and freshwater systems, these Gram-positive bacteria cause significant economic losses, estimated at hundreds of millions of dollars annually. ...

Is your lunch salad safe to eat? Occurrence of bacterial pathogens and potential for pathogen growth in pre-packed ready-to-eat mixed-ingredient salads.

PubMed

Söderqvist, Karin

2017-01-01

As part of a trend toward healthy convenience foods, ready-to-eat (RTE) mixed-ingredient salads have become popular products among consumers. A mixed-ingredient salad contains combinations of raw ( e.g . leafy vegetables and tomatoes) and processed ( e.g . chicken, salmon, ham, pasta and couscous) ingredients. Contamination of leafy vegetables can occur during any step in the production chain and, since there is no step that kills pathogens, a completely safe final product can never be guaranteed. Meat ingredients, for example poultry meat and ham, are generally heat-treated before preparation, but may be contaminated after this treatment, e.g . when diced or sliced. When several ingredients are mixed together, cross-contamination may occur. Preparation of mixed-ingredient salads requires human handling, which presents an additional risk of bacterial contamination. With high-protein ingredients, e.g . cooked meat, the mixed-ingredient salad represents an excellent substrate for bacterial growth. This article reviews current knowledge regarding human bacterial pathogen prevalence in mixed-ingredient salads and the potential for pathogen growth in this product during storage.

Is your lunch salad safe to eat? Occurrence of bacterial pathogens and potential for pathogen growth in pre-packed ready-to-eat mixed-ingredient salads

PubMed Central

Söderqvist, Karin

2017-01-01

ABSTRACT As part of a trend toward healthy convenience foods, ready-to-eat (RTE) mixed-ingredient salads have become popular products among consumers. A mixed-ingredient salad contains combinations of raw (e.g. leafy vegetables and tomatoes) and processed (e.g. chicken, salmon, ham, pasta and couscous) ingredients. Contamination of leafy vegetables can occur during any step in the production chain and, since there is no step that kills pathogens, a completely safe final product can never be guaranteed. Meat ingredients, for example poultry meat and ham, are generally heat-treated before preparation, but may be contaminated after this treatment, e.g. when diced or sliced. When several ingredients are mixed together, cross-contamination may occur. Preparation of mixed-ingredient salads requires human handling, which presents an additional risk of bacterial contamination. With high-protein ingredients, e.g. cooked meat, the mixed-ingredient salad represents an excellent substrate for bacterial growth. This article reviews current knowledge regarding human bacterial pathogen prevalence in mixed-ingredient salads and the potential for pathogen growth in this product during storage. PMID:29230273

Detection of bacterial pathogens including potential new species in human head lice from Mali

PubMed Central

Amanzougaghene, Nadia; Fenollar, Florence; Sangaré, Abdoul Karim; Sissoko, Mahamadou S.; Doumbo, Ogobara K.; Raoult, Didier

2017-01-01

In poor African countries, where no medical and biological facilities are available, the identification of potential emerging pathogens of concern at an early stage is challenging. Head lice, Pediculus humanus capitis, have a short life, feed only on human blood and do not transmit pathogens to their progeny. They are, therefore, a perfect tool for the xenodiagnosis of current or recent human infection. This study assessed the occurrence of bacterial pathogens from head lice collected in two rural villages from Mali, where a high frequency of head lice infestation had previously been reported, using molecular methods. Results show that all 600 head lice, collected from 117 individuals, belonged to clade E, specific to West Africa. Bartonella quintana, the causative agent of trench fever, was identified in three of the 600 (0.5%) head lice studied. Our study also shows, for the first time, the presence of the DNA of two pathogenic bacteria, namely Coxiella burnetii (5.1%) and Rickettsia aeschlimannii (0.6%), detected in human head lice, as well as the DNA of potential new species from the Anaplasma and Ehrlichia genera of unknown pathogenicity. The finding of several Malian head lice infected with B. quintana, C. burnetii, R. aeschlimannii, Anaplasma and Ehrlichia is alarming and highlights the need for active survey programs to define the public health consequences of the detection of these emerging bacterial pathogens in human head lice. PMID:28931077

Streptococcus suis – The “Two Faces” of a Pathobiont in the Porcine Respiratory Tract

PubMed Central

Vötsch, Désirée; Willenborg, Maren; Weldearegay, Yenehiwot B.; Valentin-Weigand, Peter

2018-01-01

Streptococcus (S.) suis is a frequent early colonizer of the upper respiratory tract of pigs. In fact, it is difficult to find S. suis-free animals under natural conditions, showing the successful adaptation of this pathogen to its porcine reservoir host. On the other hand, S. suis can cause life-threatening diseases and represents the most important bacterial cause of meningitis in pigs worldwide. Notably, S. suis can also cause zoonotic infections, such as meningitis, septicemia, endocarditis, and other diseases in humans. In Asia, it is classified as an emerging zoonotic pathogen and currently considered as one of the most important causes of bacterial meningitis in adults. The “two faces” of S. suis, one of a colonizing microbe and the other of a highly invasive pathogen, have raised many questions concerning the interpretation of diagnostic detection and the definition of virulence. Thus, one major research challenge is the identification of virulence-markers which allow differentiation of commensal and virulent strains. This is complicated by the high phenotypic and genotypic diversity of S. suis, as reflected by the occurrence of (at least) 33 capsular serotypes. In this review, we present current knowledge in the context of S. suis as a highly diverse pathobiont in the porcine respiratory tract that can exploit disrupted host homeostasis to flourish and promote inflammatory processes and invasive diseases in pigs and humans. PMID:29599763

Analysis of apple (Malus) responses to bacterial pathogens using an oligo microarray

USDA-ARS?s Scientific Manuscript database

Fire blight is a devastating disease of apple (Malus x domestica) caused by the bacterial pathogen Erwinia amylovora (Ea). When infiltrated into host leaves, Ea induces reactions similar to a hypersensitive response (HR). Type III (T3SS) associated effectors, especially DspA/E, are suspected to ha...

Genomewide Identification of Essential Genes and Fitness Determinants of Streptococcus mutans UA159

PubMed Central

Zeng, Lin; Culp, David J.

2018-01-01

ABSTRACT Transposon mutagenesis coupled with next-generation DNA sequencing (Tn-seq) is a powerful tool for discovering regions of the genome that are required for the survival of bacteria in different environments. We adapted this technique to the dental caries pathogen Streptococcus mutans UA159 and identified 11% of the genome as essential, with many genes encoding products required for replication, translation, lipid metabolism, and cell wall biogenesis. Comparison of the essential genome of S. mutans UA159 with those of selected other streptococci for which such information is available revealed several metabolic pathways and genes that are required in S. mutans, but not in some Streptococcus spp. We further identified genes that are essential for sustained growth in rich or defined medium, as well as for persistence in vivo in a rodent model of oral infection. Collectively, our results provide a novel and comprehensive view of the genes required for essential processes of S. mutans, many of which could represent potential targets for therapeutics. IMPORTANCE Tooth decay (dental caries) is a common cause of pain, impaired quality of life, and tooth loss in children and adults. It begins because of a compositional change in the microorganisms that colonize the tooth surface driven by repeated and sustained carbohydrate intake. Although several bacterial species are associated with tooth decay, Streptococcus mutans is the most common cause. Therefore, it is important to identify biological processes that contribute to the survival of S. mutans in the human mouth, with the aim of disrupting the processes with antimicrobial agents. We successfully applied Tn-seq to S. mutans, discovering genes that are required for survival, growth, and persistence, both in laboratory environments and in a mouse model of tooth decay. This work highlights new avenues for the control of an important human pathogen. PMID:29435491

Pathogenic Leptospira species express surface-exposed proteins belonging to the bacterial immunoglobulin superfamily

PubMed Central