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Schirmeister F.,German Federal Institute for Risk Assessment | Dieckmann R.,German Federal Institute for Risk Assessment | Bechlars S.,German Federal Institute for Risk Assessment | Bier N.,German Federal Institute for Risk Assessment | And 2 more authors.
European Journal of Clinical Microbiology and Infectious Diseases | Year: 2014

Vibrio cholerae belonging to the non-O1, non-O139 serogroups are present in the coastal waters of Germany and in some German and Austrian lakes. These bacteria can cause gastroenteritis and extraintestinal infections, and are transmitted through contaminated food and water. However, non-O1, non-O139 V. cholerae infections are rare in Germany. We studied 18 strains from German and Austrian patients with diarrhea or local infections for their virulence-associated genotype and phenotype to assess their potential for infectivity in anticipation of possible climatic changes that could enhance the transmission of these pathogens. The strains were examined for the presence of genes encoding cholera toxin and toxin-coregulated pilus (TCP), as well as other virulence-associated factors or markers, including hemolysins, repeats-in-toxin (RTX) toxins, Vibrio seventh pandemic islands VSP-1 and VSP-2, and the type III secretion system (TTSS). Phenotypic assays for hemolysin activity, serum resistance, and biofilm formation were also performed. A dendrogram generated by incorporating the results of these analyses revealed genetic differences of the strains correlating with their clinical origin. Non-O1, non-O139 strains from diarrheal patients possessed the TTSS and/or the multifunctional autoprocessing repeats-in-toxin (MARTX) toxin, which were not found in the strains from ear or wound infections. Routine matrix-assisted laser desorption/ionization (MALDI-TOF) mass spectrometry (MS) analysis of all strains provided reliable identification of the species but failed to differentiate between strains or clusters. The results of this study indicate the need for continued surveillance of V. cholerae non-O1, non-O139 in Germany, in view of the predicted increase in the prevalence of Vibrio spp. due to the rise in surface water temperatures. © 2013 The Author(s). Source

Zahid M.S.H.,Osaka Prefecture University | Awasthi S.P.,Osaka Prefecture University | Asakura M.,Osaka Prefecture University | Chatterjee S.,Osaka Prefecture University | And 4 more authors.
PLoS ONE | Year: 2015

Use of natural compounds as antivirulence drugs could be an alternative therapeutic approach to modify the outcome of bacterial infections, particularly in view of growing resistance to available antimicrobials. Here, we show that sub-bactericidal concentration of anethole, a component of sweet fennel seed, could suppress virulence potential in O1 El Tor biotype strains of toxigenic Vibrio cholerae, the causative agent of the ongoing 7th cholera pandemic. The expression of cholera toxin (CT) and toxin coregulated pilus (TCP), the major virulence factors of V. cholerae, is controlled through a regulatory cascade involving activation of ToxT with synergistic coupling interaction of ToxR/ToxS with TcpP/TcpH. We present evidence that anethole inhibits in vitro expression of CT and TCP in a toxT-dependent but toxR/toxS-independent manner and through repression of tcpP/tcpH, by using bead-ELISA, western blotting and quantitative real-time RT-PCR assays. The cyclic AMP (cAMP)-cAMP receptor protein (CRP) is a well-studied global signaling system in bacterial pathogens, and this complex is known to suppress expression of tcpP/tcpH in V. cholerae. We find that anethole influences the virulence regulatory cascade by over-expressing cyaA and crp genes. Moreover, suppression of toxigenic V. cholerae-mediated fluid accumulation in ligated ileum of rabbit by anethole demonstrates its potentiality as an antivirulence drug candidate against the diseases caused by toxigenic V. cholerae. Taken altogether, these results revealing a mechanism of virulence inhibition in V. cholerae by the natural compound anethole, may have relevance in designing antivirulence compounds, particularly against multiple antibiotic resistant bacterial pathogens. © 2015 Zahid et al. Source

Hinenoya A.,Osaka Prefecture University | Shima K.,Osaka Prefecture University | Shima K.,University of Lubeck | Asakura M.,Osaka Prefecture University | And 7 more authors.
BMC Microbiology | Year: 2014

Background: Cytolethal distending toxin (CDT)-producing Escherichia coli (CTEC) has been isolated from patients with gastrointestinal or urinary tract infection, and sepsis. However, the source of human infection remains unknown. In this study, we attempted to detect and isolate CTEC strains from fecal specimens of healthy farm animals and characterized them phenotypically and genotypically. Results: By PCR analysis, the cdtB gene was detected in 90 and 14 out of 102 and 45 stool specimens of healthy cattle and swine, respectively, and none from 45 chicken samples. Subtypes of the cdtB genes (I to V) were further examined by restriction fragment length polymorphism analysis of the amplicons and by type-specific PCRs for the cdt-III and cdt-V genes. Of the 90 cdtB gene-positive cattle samples, 2 cdt-I, 25 cdt-III, 1 cdt-IV, 52 cdt-V and 1 both cdt-III and cdt-V gene-positive strains were isolated while 1 cdt-II and 6 cdt-V gene-positive were isolated from 14 cdtB positive swine samples. Serotypes of some isolates were identical to those of human isolates. Interestingly, a cdt-II gene-positive strain isolated from swine was for the first time identified as Escherichia albertii. Phylogenetic analysis grouped 87 E. coli strains into 77 phylogroup B1, 6 B2, and 4 D, respectively. Most of the B1 strains harbored both lpfA O113 and ehaA. Three and twenty-two cdt-V gene-positive strains harbored eaeA and stx genes, respectively, and seven possessed cdt-V, stx and subAB genes. The cnf2 gene, normally present in cdt-III gene-positive strains, was also detected in cdt-V gene-positive strains. Conclusions: Our results suggest that healthy cattle and swine could be the reservoir of CTEC, and they could be a potential source of human infections. © 2014 Hinenoya et al.; licensee BioMed Central Ltd. Source

Faruque S.M.,Center for Food and Water Borne Diseases
Current Topics in Microbiology and Immunology | Year: 2014

Understanding the genetic and ecological factors which support the periodic emergence of toxigenic Vibrio cholerae causing outbreaks of cholera in regions where the disease is endemic, is vital to develop preventive measures. Besides environmental factors which are not precisely defined, bacteriophages, and horizontally transmissible genetic elements are known to have a significant role in the epidemiology and evolution of the pathogen. Cholera epidemics are also known to be self-limiting, and hence identifying natural factors which contribute to the collapse of epidemics may have important implications in controlling the disease. Phages have been shown to play a crucial role in modulating cholera epidemics, and enhance V. cholerae evolution through a bactericidal selection process which favors the emergence of new clones. © 2014 Springer-Verlag Berlin Heidelberg. Source

Kamruzzaman M.,University of Sydney | Kamruzzaman M.,Westmead Millennium Institute | Kamruzzaman M.,Center for Food and Water Borne Diseases | Shoma S.,University of Sydney | And 14 more authors.
Diagnostic Microbiology and Infectious Disease | Year: 2013

The extended-spectrum β-lactamase gene blaCTX-M-15 was almost ubiquitous in diverse antibiotic-resistant Escherichia coli isolated from surface water around Dhaka City, Bangladesh. Forty-eight isolates represented 34 multi-locus sequence types and a variety of plasmid replicons were identified in association with blaCTX-M-15 and other resistance genes. This water is likely to be an important source of transmissible antibiotic resistance in Bangladesh. © 2013 Elsevier Inc. Source

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