Zoonotic Bacterial Pathogens Research Articles

Attenuation of E. coli O157:H7 virulence by a combination of natural plant extracts and organic acids before and after refrigerated storage

Anti-virulence strategies are an alternative approach to combat zoonotic bacterial pathogens. Although control measures are in place against E. coli O157, it still remains a global health concern with cattle being the most important reservoir. Different feed constituents have varying effects on the virulence of E. coli O157 present in the gut which then are transferred to meat processing surfaces and meat during slaughter. This study explored the anti-virulence properties of a mixture of natural plant extracts and organic acids (citrus, grape and oregano extracts, lactic and citric acid) before and after refrigerated storage as means of reducing the risk from E. coli O157 by reducing its virulence. Assessment of the effects of sub-inhibitory concentrations (0.1 and 0.5 %, v/v) of the antimicrobial mixture before refrigerated storage showed that the pathogen’s motility and adhesion onto HCT-8 cells was significantly reduced (P<0.05) in a dose-dependent manner. Shiga-toxin 2 production was also significantly reduced. Real-time PCR analysis revealed that the mixture of natural antimicrobials repressed expression of adhesion (eae) and shiga-toxin 2 (stx2) genes, which was consistent with the observed reduction in adhesion and toxin production. The same virulence factors were investigated after simulated storage of E. coli O157 in meat simulation medium. Results revealed that after exposure to the antimicrobial mixture, the virulence was significantly lower compared to non-treated control after refrigerated storage. The present work shows the potential of the antimicrobial mixture in reducing virulence and thus risk from E. coli O157 by applying it as a feed additive.

Lactobacillus casei suppresses hfq gene expression in Escherichia coli O157:H7

Enterohaemorrhagic Escherichia coli O157:H7 is a zoonotic food and waterborne bacterial pathogen that causes a high hospitalization rate and life-threatening complications including seizures, cereb...

Impact of winter enclosures on the gut bacterial microbiota of red deer in the Bavarian Forest National Park

High numbers of red deer Cervus elaphus pose a challenge for natural forests because of their high browsing intensities, especially during winter months. To mitigate this human–wildlife conflict, conservation management in central Europe involves luring red deer into fenced winter-feeding sites. The supplementary food provided in these so-called winter enclosures strongly differs from the natural diet of red deer. Dietary shifts, however, can lead to an imbalance of the gut microbiota, which could promote bacterial pathogens. Moreover, increased inter-individual contact in winter enclosures enhances the exchange of symbiotic but also pathogenic bacteria. In this study, we used high-throughput sequencing of the 16S rRNA gene in fecal samples of red deer inhabiting the Bavarian Forest National Park to investigate differences in the gut bacterial microbiota between individuals in winter enclosures and individuals that ranged freely in the forests in winter. We also investigated the occurrence of potential zoonotic bacterial pathogens in both study groups. Our results revealed that proportions of bacterial taxa, alpha- and beta-diversities, and relative abundances of amplicon sequence variants in the gut bacterial microbiota of the two groups differed. These differences were attributed to the enrichment of bacterial taxa involved in the digestion of the supplementary food and to different natural diets consumed before entering the winter enclosures. We detected sequences with high similarities to known red deer pathogens in both study groups, but their relative abundances were low, which suggests that the population of red deer of the Bavarian Forest National Park is healthy.

Zoonotic and economically significant pathogens of peri-urban wild dogs across north-eastern New South Wales and south-eastern Queensland, Australia

Context Peri-urban wild dogs are known to reside within high-risk and densely populated regions and are capable of harbouring a variety of zoonotic pathogens. Despite recognising the potential of peri-urban wild dogs to carry zoonotic pathogens, limited prevalence data are currently available to assist in understanding the potential risks that peri-urban wild dogs pose within developed communities. Aims The aim of the present research was to establish the current status of key zoonotic and economically significant pathogens in peri-urban wild dogs. Methods Two hundred and one peri-urban wild dog cadavers were collected from south-eastern Queensland and northern New South Wales. In addition, whole blood, serum and faecal samples were also collected. Pathogens were identified through several morphological, microbiological and molecular methods. Key results Helminth parasites were detected within 79.6% of peri-urban wild dogs; Echinococcus granulosus was the most common pathogen, with adult worms being detected within 50.7 ± 6.9% of intestines, followed by Spirometra erinacei (36.6 ± 6.4%); hookworms, including Ancylostoma caninum and Uncinaria stenocephala (28.8 ± 7.1%); Toxocara canis (5.4 ± 3.1%) and Taenia spp., including T. serialis and T. pisiformis (4.5 ± 2.8%). Bacterial pathogens detected included methicillin-resistant Escherichia coli (20.0 ± 10.1%), Salmonella spp. (3.7 ± 4.0%) and methicillin-sensitive Staphylococcus aureus (3.3 ± 2.7%). Conclusions The present study is the most comprehensive investigation of zoonotic pathogen carriage in peri-urban wild dogs in Australia. Parasitic infections in peri-urban wild dogs are common, with tapeworms representing the majority of intestinal pathogens. Important zoonotic bacterial pathogens are carried by peri-urban wild dogs, although at a much lower prevalence than are parasites. Implications The presence of these pathogens in free-ranging peri-urban dog populations suggests a strong potential for public health risk, most notably from E. granulosus. These data are inherently important as baseline information, which is essential to guide risk-based management of peri-urban wild dog impacts.

Prevalence and genomic characteristics of zoonotic gastro-intestinal pathogens and ESBL/pAmpC producing Enterobacteriaceae among Swedish corvid birds

ABSTRACTIntroduction: Wild birds pose a potential threat to animal and human health by spreading infectious diseases. In the present study, we studied the occurrence of bacterial zoonotic pathogens as well as enterobacteria with transferrable antimicrobial resistance genes among Swedish corvids.Materials and methods: Intestines from 66 jackdaws, crows, rooks and magpies from the vicinity of livestock farms at 14 locations in 7 counties were analysed by direct culture or PCR screening followed by culture. Isolates were investigated by whole-genome sequencing.Results and discussion: Campylobacter jejuni were detected in 82% and Yersinia in 3% of the birds. ESBL-producing E. coli were found in one sample (2%) and carried blaCTX-M-55. No Enterobacteriaceae with transferable carbapenem resistance were identified. No Salmonella or E. coli O157:H7 were found, but PCR analysis for enterohaemorrhagic E. coli virulence genes revealed 35% positive samples for intimin, 9% for verotoxin 1 and 17% for verotoxin 2. C. jejuni isolates from corvids were compared to previously published isolates from Swedish sources by multi-locus sequence typing based on genome sequences. All corvid C. jejuni isolates formed a cluster, intermingled with human and chicken isolates. Our results indicate that C. jejuni is ubiquitous among Swedish corvid birds, with sporadic transmission to poultry and humans.

Fungal pathogens pose a potential threat to animal and plant health in desertified and pika-burrowed alpine meadows on the Tibetan Plateau.

Intact Tibetan meadows provide significant defense against soil-borne pathogen dispersal. However, dramatic meadow degradation has been observed due to climate change and pika damage, but their impacts on soil-borne pathogens are still unclear. With approximately 40% of the world's population living in Tibetan Plateau and its downstream watersheds, this lack of knowledge should be of great concern. Here, we used Illumina amplicon sequencing to characterize the changes in potential human, domestic animal, plant, and zoonotic bacterial and fungal pathogens in nondegraded, desertified, and pika-burrowed meadows. The relative abundance of bacterial domestic animal pathogens and zoonotic pathogens were significantly increased by desertification. Pika burrowing significantly increased the relative abundance of bacterial human pathogens and zoonotic pathogens. The species richness and relative abundance of fungal pathogens was significantly increased by desertification and pika burrowing. Accordingly, fungal plant and animal pathogens categorized by FUNGuid significantly increased in desertified and pika-burrowed meadows. Soil chemical and plant properties explained 38% and 64% of the bacterial and fungal pathogen community variance, respectively. Therefore, our study indicates for the first time that both alpine meadow desertification and pika burrowing could potentially increase infectious disease risks in the alpine ecosystem, especially for fungal diseases.

Antibiotic resistant zoonotic bacteria in Irrawaddy squirrel (Callosciurus pygerythrus).

Irrawaddy squirrel (Callosciurus pygerythrus) may play an important role in the transmission of zoonotic bacteria, but little is known about the carriage of zoonotic bacteria in this common frugivorous rodent in Bangladesh. We aimed to investigate the presence of common zoonotic bacterial pathogens in Irrawaddy squirrel in the southeast part of Bangladesh. A total of 27 rectal and 27 oro‐nasal swabs were collected from 27 healthy wild Irrawaddy squirrels. Four common zoonotic bacteria were isolated following routine laboratory procedures, and were identified based on colony morphology, and biochemical and staining properties. The pathogenic potential of the identified bacteria was confirmed by detection of virulence genes by PCR. All isolates were subjected to antimicrobial susceptibility test against seven antibiotics from six generic groups which are commonly used in human and veterinary medicine in Bangladesh. The prevalence of Escherichia coli, Salmonella spp., Yersinia spp. and Staphylococcus spp. was 44.4% (95% CI, 32.0–57.6), 13% (95% CI, 6.1–24.7), 44.4% (95% CI, 32.0–57.6), and 72.2% (95% CI, 59.0–82.5), respectively. We identified potential zoonotic virulence genes in all of these four bacterial species. Antimicrobial susceptibility testing revealed the presence of several multidrug resistant bacterial strains in squirrels. To the best of our knowledge, this is the first report in Bangladesh of the detection of antibiotic resistant zoonotic bacteria in Irrawaddy squirrels. The findings underpin the role of Irrawaddy squirrel as a source of pathogenic antibiotic resistant bacteria, consequently, fruit rejected because of squirrel consumption and squirrel‐bites deserve more concern than previously.

Transposon Sequencing of Brucella abortus Uncovers Essential Genes for Growth In Vitro and Inside Macrophages.

Brucella abortus is a class III zoonotic bacterial pathogen able to survive and replicate inside host cells, including macrophages. Here we report a multidimensional transposon sequencing analysis to identify genes essential for Brucella abortus growth in rich medium and replication in RAW 264.7 macrophages. The construction of a dense transposon mutant library and mapping of 929,769 unique mini-Tn5 insertion sites in the genome allowed identification of 491 essential coding sequences and essential segments in the B. abortus genome. Chromosome II carries a lower proportion (5%) of essential genes than chromosome I (19%), supporting the hypothesis of a recent acquisition of a megaplasmid as the origin of chromosome II. Temporally resolved transposon sequencing analysis as a function of macrophage infection stages identified 79 genes with a specific attenuation phenotype in macrophages, at either 2, 5, or 24 h postinfection, and 86 genes for which the attenuated mutant phenotype correlated with a growth defect on plates. We identified 48 genes required for intracellular growth, including the virB operon, encoding the type IV secretion system, which supports the validity of the screen. The remaining genes encode amino acid and pyrimidine biosynthesis, electron transfer systems, transcriptional regulators, and transporters. In particular, we report the need of an intact pyrimidine nucleotide biosynthesis pathway in order for B. abortus to proliferate inside RAW 264.7 macrophages.

Bartonella henselae and Rickettsia felis Detected in Cat Fleas (Ctenocephalides felis) Derived from Eastern Austrian Cats.

Cats and cat fleas (Ctenocephalides felis) are vectors of the zoonotic bacterial pathogens Bartonella henselae and Rickettsia felis, which are the causative agents of "cat scratch disease" and "cat flea typhus," respectively. In the surroundings of Vienna (Austria), we identified 11 (10.5%; n = 105) B. henselae-positive fleas originating from 8 cats (20.5%; n = 39). One flea was positive for R. felis. There should be high levels of awareness among veterinarians and animal keepers as to the handling of cats, especially if free roaming, stray, or feral.

Antibiotic Use in Agriculture and Its Consequential Resistance in Environmental Sources: Potential Public Health Implications.

Due to the increased demand of animal protein in developing countries, intensive farming is instigated, which results in antibiotic residues in animal-derived products, and eventually, antibiotic resistance. Antibiotic resistance is of great public health concern because the antibiotic-resistant bacteria associated with the animals may be pathogenic to humans, easily transmitted to humans via food chains, and widely disseminated in the environment via animal wastes. These may cause complicated, untreatable, and prolonged infections in humans, leading to higher healthcare cost and sometimes death. In the said countries, antibiotic resistance is so complex and difficult, due to irrational use of antibiotics both in the clinical and agriculture settings, low socioeconomic status, poor sanitation and hygienic status, as well as that zoonotic bacterial pathogens are not regularly cultured, and their resistance to commonly used antibiotics are scarcely investigated (poor surveillance systems). The challenges that follow are of local, national, regional, and international dimensions, as there are no geographic boundaries to impede the spread of antibiotic resistance. In addition, the information assembled in this study through a thorough review of published findings, emphasized the presence of antibiotics in animal-derived products and the phenomenon of multidrug resistance in environmental samples. This therefore calls for strengthening of regulations that direct antibiotic manufacture, distribution, dispensing, and prescription, hence fostering antibiotic stewardship. Joint collaboration across the world with international bodies is needed to assist the developing countries to implement good surveillance of antibiotic use and antibiotic resistance.

Zoonotic bacteria and parasites found in raw meat-based diets for cats and dogs

Feeding raw meat-based diets (RMBDs) to companion animals has become increasingly popular. Since these diets may be contaminated with bacteria and parasites, they may pose a risk to both animal...

Consumption of antibacterial molecules in broiler production in Morocco.

Monitoring the use of antibacterial agents in food‐producing animals is crucial in order to reduce antimicrobial resistance, selection and dissemination of resistant bacterial strains, and drug residues in the animal food products. The broiler production sector is considered a great consumer of antibacterials and incriminated in the rise of antimicrobial resistance level in zoonotic bacterial pathogens such as Escherichia coli, Salmonella and Campylobacter. Following recommendations from the OIE and WHO, a survey was conducted about the use and consumption of several antibacterial agents in Moroccan broiler flocks. More than 5 million broilers were randomly surveyed at the prescriber level, that is, via the veterinary clinics involved in their health management. The results showed that 93% of the flocks received at least one antibacterial treatment of minimum 3 days duration. Enrofloxacin, colistin and trimethoprim/sulphonamides were the most used antibacterials followed by oxytetracycline, florfenicol and amoxicillin. Oxytetracycline, enrofloxacin and colistin were overdosed in most of the administration, while amoxicillin and the combination of trimethoprim/sulphonamides were under‐dosed. The total amount of antibacterial consumed in the survey was 63.48 mg/kg and the Animal Level of Exposure to Antimicrobials (ALEA) was 94.45%. The reasons for this frequent use were related mainly to the poor quality of broiler production management. Chicks and animal feed provided to producers were of variable quality. Management of rearing stock density was often poor and biosecurity inadequate, and broilers were challenged by a high prevalence of infectious diseases.

Pathogenic potentials and shedding probability of Salmonella enterica serotype Kentucky in experimentally infected backyard chicken

Objective: Salmonella is a widely-reported zoonotic bacterial pathogen and human infection is mostly attributed through direct or indirect contact with chickens. Salmonella Kentucky (S. Kentucky) is one of the motile serovars which has recently been identified from both poultry and human samples in Bangladesh. This study was conducted to assess its pathogenic potentials and shedding probability in backyard chicken. Materials and methods: We infected 22 backyard chickens orally, each with 106 cfu of Salmonella Kentuckey, which were then observed for 23 days to enlist clinical signs, gross and histo-pathological changes. Polymerase chain reaction (PCR) for Salmonella was applied on some representative samples to identify the presence of Salmonella. Results: Four chickens were sacrificed and the internal organs were examined to observe gross and microscopic tissue changes. Some reactive changes were seen in spleen during prolonged course of infection. The probability of S. Kentucky shedding was 77% (95%; CI 54-90%) on DPI 2, 41% (95%; CI 21-60%) on DPI 12 and 13% (95%; CI 3-31%) on DPI 21. The survival probability of the infected chickens was 50% (95%; CI 28-68%) on DPI 6, 32% (95%; CI 14-51%) on DPI 15 and 14% (95%; CI 3-31%) on DPI 23. Conclusion: Zoonotic S. Kentucky strain of human non-typhoidal clinical cases of gastroenteritis has potentials to produce clinical signs such as reduced feed uptake, watery or pasty fecal droppings and lesions, such as catarrhal enteritis and typhlitis.

The orange spotted cockroach (Blaptica dubia, Serville 1839) is a permissive experimental host for Francisella tularensis

Francisella tularensis is a zoonotic bacterial pathogen that causes severe disease in a wide range of host animals, including humans. Well-developed murine models of F. tularensis pathogenesis are available, but they do not meet the needs of all investigators. However, researchers are increasingly turning to insect host systems as a cost-effective alternative that allows greater increased experimental throughput without the regulatory requirements associated with the use of mammals in biomedical research. Unfortunately, the utility of previously-described insect hosts is limited because of temperature restriction, short lifespans, and concerns about the immunological status of insects mass-produced for other purposes. Here, we present a novel host species, the orange spotted (OS) cockroach (Blaptica dubia), that overcomes these limitations and is readily infected by F. tularensis. Intrahemocoel inoculation was accomplished using standard laboratory equipment and lethality was directly proportional to the number of bacteria injected. Progression of infection differed in insects housed at low and high temperatures and F. tularensis mutants lacking key virulence components were attenuated in OS cockroaches. Finally, antibiotics were delivered to infected OS cockroaches by systemic injection and controlled feeding; in the latter case, protection correlated with oral bioavailability in mammals. Collectively, these results demonstrate that this new host system provides investigators with a new tool capable of interrogating F. tularensis virulence and immune evasion in situations where mammalian models are not available or appropriate, such as undirected screens of large mutant libraries.

Zoonotic Importance of Some Pathogenic Bacteria Isolated from Small Ruminants' Milk and Hands of Dairy Workers

Staphylococcus aureus and enteropathogenic Escherichia coli are among zoonotic bacterial food-borne pathogens causing illness ranged from diarrhoea to fatal conditions. This study was undertaken to evaluate the occurrence of Staph. aureus and E. coli in small ruminants' raw milk and hands of dairy workers at small-scale production units, Giza, Egypt. A total of 420 raw milk samples were obtained from apparently healthy sheep and goats, also, hand swabs (n=46) from workers at the units under investigation were examined. Overall, Staph. aureus (13.1%, 55/420) and E. coli (26.2%, 110/420) isolates were obtained from raw milk of sheep and goats. However, only Staph. aureus (15.2%, 7/46) was recovered from hand swabs of dairy workers. Using PCR, all the tested Staph. aureus isolates from milk and hand swabs yielded specific bands of Thermonuclease ( nuc ) gene at 279 bp, however, amplification of virulence ( eae ) gene encoding the intimin protein of E. coli produced an amplicon of 917 bp in 45% of the tested E. coli isolates. In conclusion, our findings provide an overview about Staph. aureus and E. coli contamination in raw milk of small ruminants locally bred by smallholders and suggest probably transmission of Staph. aureus from hands of dairy workers that contaminate the milk or udder of apparently healthy animals. Reporting of such organisms from milk indicates the need for strict hygienic measures during milking at these production units.

Domestic sheep show average Coxiella burnetii seropositivity generations after a sheep-associated human Q fever outbreak and lack detectable shedding by placental, vaginal, and fecal routes.

Coxiella burnetii is a globally distributed zoonotic bacterial pathogen that causes abortions in ruminant livestock. In humans, an influenza-like illness results with the potential for hospitalization, chronic infection, abortion, and fatal endocarditis. Ruminant livestock, particularly small ruminants, are hypothesized to be the primary transmission source to humans. A recent Netherlands outbreak from 2007–2010 traced to dairy goats resulted in over 4,100 human cases with estimated costs of more than 300 million euros. Smaller human Q fever outbreaks of small ruminant origin have occurred in the United States, and characterizing shedding is important to understand the risk of future outbreaks. In this study, we assessed bacterial shedding and seroprevalence in 100 sheep from an Idaho location associated with a 1984 human Q fever outbreak. We observed 5% seropositivity, which was not significantly different from the national average of 2.7% for the U.S. (P>0.05). Furthermore, C. burnetii was not detected by quantitative PCR from placentas, vaginal swabs, or fecal samples. Specifically, a three-target quantitative PCR of placenta identified 0.0% shedding (exact 95% confidence interval: 0.0%-2.9%). While presence of seropositive individuals demonstrates some historical C. burnetii exposure, the placental sample confidence interval suggests 2016 shedding events were rare or absent. The location maintained the flock with little or no depopulation in 1984 and without C. burnetii vaccination during or since 1984. It is not clear how a zero-shedding rate was achieved in these sheep beyond natural immunity, and more work is required to discover and assess possible factors that may contribute towards achieving zero-shedding status. We provide the first U.S. sheep placental C. burnetii shedding update in over 60 years and demonstrate potential for C. burnetii shedding to reach undetectable levels after an outbreak event even in the absence of targeted interventions, such as vaccination.

Alternative Growth Promoters Modulate Broiler Gut Microbiome and Enhance Body Weight Gain.

Antibiotic growth promoters (AGPs) are frequently used to enhance weight-gain in poultry production. However, there has been increasing concern over the impact of AGP on the emergence of antibiotic resistance in zoonotic bacterial pathogens in the microbial community of the poultry gut. In this study, we adopted mass-spectrophotometric, phylogenetic, and shotgun-metagenomic approaches to evaluate bioactive phenolic extracts (BPE) from blueberry (Vaccinium corymbosum) and blackberry (Rubus fruticosus) pomaces as AGP alternatives in broilers. We conducted two trials with 100 Cobb-500 broiler chicks (in each trial) in four equal groups that were provided water with no supplementation, supplemented with AGP (tylosin, neomycin sulfate, bacitracin, erythromycin, and oxytetracycline), or supplemented with 0.1 g Gallic acid equivalent (GAE)/L or 1.0 g GAE/L (during the last 72 h before euthanasia) of BPE for 6 weeks. When compared with the control group (water only), the chickens supplemented with AGP and 0.1 g GAE/L of BPE gained 9.5 and 5.8% more body weight, respectively. The microbiomes of both the AGP- and BPE-treated chickens had higher Firmicutes to Bacteroidetes ratios. AGP supplementation appeared to be associated with higher relative abundance of bacteriophages and unique cecal resistomes compared with BPE supplementation or control. Functional characterization of cecal microbiomes revealed significant animal-to-animal variation in the relative abundance of genes involved in energy and carbohydrate metabolism. These findings established a baseline upon which mechanisms of plant-based performance enhancers in regulation of animal growth can be investigated. In addition, the data will aid in designing alternate strategies to improve animal growth performance and consequently production.

Starry Heart Valve: A Story Behind CAT Scratch

SESSION TITLE: Bacterial Infections 1 SESSION TYPE: Affiliate Case Report Poster PRESENTED ON: Tuesday, October 31, 2017 at 01:30 PM - 02:30 PM INTRODUCTION: Bartonella species are zoonotic bacterial pathogens in humans. B.quintana and B.henselae are the most common agents causing human infections. B.henselae infection is associated with exposure to cats and their fleas; endocarditis may occur in patients with known valvular disease. CASE PRESENTATION: A 62-year-old female, with no prior history of heart disease, presented with 10 days of bilateral leg swelling, malaise and exertional dyspnea. She lived with her 4 cats. Examination was notable for bilateral pitting edema extending to her waist with visible scratch marks on her abdomen and lower extremities. Laboratory data revealed new pancytopenia and an elevated serum creatinine (2.1 mg/dl). She was started on clindamycin for cellulitis. Blood cultures were negative. Transthoracic echocardiogram, obtained to evaluate the severe edema, showed an aortic valve vegetation measuring 2.7 cm x 1.3 cm with aortic insufficiency. The lesion was confirmed with a transesophageal study. The patient was deemed to have culture negative endocarditis; antibiotics were changed to vancomycin, ceftriaxone and doxycycline. B.henselae and B.quintana IgG titers were positive with the titer of > 1:1024. She underwent an aortic valve replacement. PCR of the heart valve tissue was positive for Bartonella. The bacterial colonies were strongly positive by Warthin Starry stain and demonstrated strong reactivity with a Bartonella immunostain. Vancomycin and ceftriaxone were discontinued; she was transitioned to doxycycline 100 mg twice daily with rifampin 300 mg twice daily for six weeks followed by doxycycline monotherapy for 6 months. DISCUSSION: Patients with Bartonella endocarditis generally present with subacute, nonspecific symptoms including fever, fatigue, weakness, and weight loss, like our patient. Our patient’s exposure to her four cats, with frequent scratches on her thighs and lower abdomen, and a culture-negative valuvular vegetation, raised the suspicion of Bartonella endocarditis. There are several methods to confirm the presence of Bartonella infection including tissue cell culture, Warthin-Starry staining of the resected valve, immuno histologic methods, serologic testing, and PCR amplification using valve specimens. If Bartonella is proven, treatment with 6 weeks of doxycycline along with 2 weeks of gentamycin and rifampin is recommended. However, there are no set guidelines defining optimal duration of therapy. Anecdotal evidences support extended doxycycline therapy for 3-6 months to prevent potential dissemination. CONCLUSIONS: Clinicians should suspect Bartonella endocarditis in patients with culture-negative endocarditis who have had extensive contact to cats. Reference #1: Chomel B et al: Fatal Case of Endocarditis Associated with Bartonella henselae Type I Infection in a Domestic Cat. Journal Of Clinical Microbiology; Nov. 2003, p. 5337-5339 Reference #2: Drancourt M et al: Bartonella (rochalimaea) quintana endocarditis in three homeless men. N Engl J Med 1995;332: 419-23 DISCLOSURE: The following authors have nothing to disclose: Thushara Paul, Siddhant Datta No Product/Research Disclosure Information

Antimicrobial activities of thiazole, imidazolidine, tetrahydropyrimidine derivatives and silver/polyvinyl alcohol nanocomposites against selected zoonotic fish bacterial pathogens

One of the serious problems faced by health and food security is the spread of drug-resistant zoonotic aquatic bacterial pathogens. For this reason, identification and application of new antibacterial agents are required. In this study, inhibitory effects of thiazole, imidazolidine and tetrahydropyrimidine derivatives and silver/polyvinyl alcohol (Ag/PVA) nanocomposites were evaluated against three important zoonotic fish bacterial pathogens namely Streptococcus iniae, Edwardsiella tarda and Aeromonas hydrophila. Ag/PVA nanocomposite was found to inhibit growth of all tested bacteria, the highest activity was observed against S. iniae with minimum inhibitory concentration (MIC) of 256 μg ml-1 and inhibition zone diameter (IZD) of 10.2 mm. No inhibitory effects were observed with imidazolidines10a-c, tetrahydropyrimidines 10d-e and thiazoles 6a-c. Among heterocyclic compounds, only thiazole derivatives 6d and 8 had inhibitory effects onS. iniae and E. tarda with MIC values of 32-256 μg ml-1 but lacked antibacterial activity against A. hydrophila.

Correction: Comparison of French and Worldwide Bacillus anthracis Strains Favors a Recent, Post-Columbian Origin of the Predominant North-American Clade

[This corrects the article DOI: 10.1371/journal.pone.0146216.].