Non-O1, non-O139 Vibrio cholerae can cause gastroenteritis and extraintestinal infections, but, unlike O1 and O139 strains of V. cholerae, little is known about the virulence gene content of non-O1, non-O139 strains and their phylogenetic relationship to other pathogenic V. cholerae. Comparative genomic microarray analysis of four pathogenic non-O1, non-O139 strains indicates that these strains are quite divergent from O1 and O139 strains. Genomic sequence analysis of a non-O1, non-O139 strain (AM-19226) that appeared particularly pathogenic in experimental animals suggests that this strain carries a type III secretion system (TTSS) that is related to the TTSS2 gene cluster found in a pandemic clone of Vibrio parahaemolyticus. The genes for this V. cholerae TTSS system appear to be present in many clinical and environmental non-O1, non-O139 strains, including at least one clone that is globally distributed. We hypothesize that the TTSS present in some pathogenic strains of non-O1, non-O139

Cholera outbreaks in subSaharan African countries are caused by strains of the El Tor biotype of toxigenic Vibrio cholerae O1. The El Tor biotype is the causative agent of the current seventh cholera pandemic, whereas the classical biotype, which was associated with the sixth pandemic, is now extinct. Besides other genetic differences the CTX prophages encoding cholera toxin in the two biotypes of V. cholerae O1 have distinct repressor (rstR) genes. However, recent incidences of cholera in Mozambique were caused by an El Tor biotype V. cholerae O1 strain that, unusually, carries a classical type (CTX class ) prophage. We conducted genomic analysis of the Mozambique strain and its CTX prophage together with chromosomal phage integration sites to understand the origin of this atypical strain and its evolutionary relationship with the true seventh pandemic strain. These analyses showed that the Mozambique strain carries two copies of CTX class prophage located on the small chromosome in a tandem array that allows excision of the prophage, but the excised phage genome was deficient in replication and did not produce CTX class virion. Comparative genomic microarray analysis revealed that the strain shares most of its genes with the typical El Tor strain N16961 but did not carry the TLC gene cluster, and RS1 sequence, adjacent to the CTX prophage. Our data are consistent with the Mozambique strain's having evolved from a progenitor similar to the seventh pandemic strain, involving multiple recombination events and suggest a model for origination of El Tor strains carrying the classical CTX prophage. cholera ͉ CTX phage ͉ TLC element ͉ evolution C holera caused by toxigenic Vibrio cholerae is a major public health problem confronting many developing countries, where outbreaks occur frequently and are particularly associated with poverty and poor sanitation (1, 2). The occurrence of seven distinct pandemics of cholera have been recorded since the beginning of the first pandemic in 1817. The current seventh pandemic, which originated in Indonesia in 1961, is the most extensive in geographic spread and duration, and the causative agent is V. cholerae O1 of the El Tor biotype. The sixth pandemic and presumably the earlier pandemics were caused by V. cholerae O1 of the classical biotype. These two biotypes of V. cholerae O1 differ in certain phenotypic and genetic characteristics (2). In toxigenic V. cholerae, the genes encoding cholera toxin (ctxAB) are part of the CTX prophage (3). Besides other genetic differences between the two biotypes of V. cholerae O1, the CTX prophages in these two biotypes are also distinct in their sequence of the repressor gene (rstR), although most of the phage genomes are similar in the two biotypes (4, 5). The factors that led to the extinction of the classical biotype and its replacement by the El Tor biotype of V. cholerae O1 as a causative agent of cholera are not clearly known.The seventh pandemic of cholera reached sub-Saharan West Africa in the early 1970s and caused explosive outbreaks...

The emergence of multidrug-resistant enterococci (MDRE) and particularly vancomycin-resistant enterococci (VRE) is considered a serious health problem worldwide, causing the need for new antimicrobials. The aim of this study was to discover and characterize bacteriocin against clinical isolates of MDRE and VRE. Over 10,000 bacterial isolates from water, environment and clinical samples were screened. E. faecalis strain 478 isolated from human feces produced the highest antibacterial activity against several MDRE and VRE strains. The optimum condition for bacteriocin production was cultivation in MRS broth at 37°C, pH 5–6 for 16 hours. The bacteriocin-like substance produced from E. faecalis strain EF478 was stable at 60°C for at least 1 hour and retained its antimicrobial activity after storage at -20°C for 1 year, at 4°C for 6 months, and at 25°C for 2 months. A nano-HPLC electrospray ionization multi-stage tandem mass spectrometry (nLC-ESI-MS/MS) analysis showed that the amino acid sequences of the bacteriocin-like substance was similar to serine protease of E. faecalis, gi|488296663 (NCBI database), which has never been reported as a bacteriocin. This study reported a novel bacteriocin with high antibacterial activity against VRE and MDRE.

Noroviruses (NoVs) are recognized as a significant cause of acute gastroenteritis in children and adults. A 14-month study, from January 2006 to February 2007, was undertaken in a hospital in Thailand to determine the prevalence and genetic characterization of NoVs in patients of all ages with acute gastroenteritis. Based on reverse transcription-nested polymerase chain reaction (RT-nested PCR), NoVs were detected in 122 of 273 (44.7%) collected stool samples. Of the 122 NoV-positive samples, 28 (23%) belonged to GI, 79 (64.8%) belonged to GII, and 15 (12.2%) were mixed infections of GI and GII strains. Three NoV GI-positive and 42 NoV GII-positive samples were characterized successfully by DNA sequencing of the RT-nested PCR products and phylogenetic analysis. For NoV GI, two genotypes were identified: GI-2 (one sample) and GI-6 (two samples). NoV GII could be classified further into five distinct genotypes: GII-2 (1 sample), GII-3 (3 samples), GII-4 (14 samples), GII-6 (3 samples), and GII-17 (2 samples), and one unclassified genotype (19 samples). All NoV GII-4 strains showed 88-98% nucleotide identity with NoV GII-4 2006b variants reported worldwide. Among genotypes of NoV characterized, one co-infected stool sample exhibited NoVs GI-6 and GII-4 2006b. This study suggests that there is an important role of NoVs as etiologic agents in patients with acute gastroenteritis. The predominant circulating genotype of NoV infections is GII-4 2006b variant.

Background Staphylococcus spp. are major cause of bovine mastitis (BM) worldwide leading to economic damage to dairy farms and public health threat. Recently, a newly emerged Staphylococcus argenteus has been found as a human and animal pathogen. Molecular characteristics, virulence and antibiotic resistant phenotypes of bacteria causing BM in Thailand are rare. This study aimed to investigated Staphylococcus spp. associated with subclinical bovine mastitis (SCM) in Thailand. Methods Milk samples were collected from 224 cows of 52 dairy herds in four central and northeast provinces. Total somatic cell counts (SCC) and California mastitis test (CMT) were used to identify SCM cows. Milk samples were cultured for Staphylococcus spp. Coagulase-positive isolates were subjected to pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST). Organisms suspected as S. argenteus were verified by detecting nonribosomal peptide synthetase gene. All isolates were checked for antibiograms and the presence of various virulence genes. Results From the 224 milk samples of 224 cows, 132 (59%) were positive for SCM by SCC and CMT and 229 staphylococcal isolates were recovered. They were 32 coagulase-positive (24 S. aureus and eight S. argenteus) and 197 coagulase-negative. PFGE of the S. aureus and S. argenteus revealed 11 clusters and a non-typeable pattern. MLST of representatives of the 11 PFGE clusters, three PFGE non-typeable S. aureus isolates from different locations and S. argenteus showed 12 sequence types. The eight S. argenteus isolates belonged to ST1223 (three isolates), ST2250 (two isolates), and ST2793 (two isolates). The antimicrobial tests identified 11 (46%) methicillin-resistant S. aureus and 25 (13%) methicillin-resistant coagulase-negative isolates, while seven S. argenteus were methicillin-susceptible and one isolate was methicillin-resistant. All of the 229 isolates were multiply resistant to other antibiotics. The most prevalent virulence genes of the 24 S. aureus isolates were clfA, coa and spa (X and IgG-binding region) (100%), hla (96%), pvl (96%) and sec (79%). Six S. argenteus isolates carried one enterotoxin gene each and other virulence genes including coa, clfA, hla/hlb, spa, tsst and pvl, indicating their pathogenic potential. Conclusion and perspective This is the first report on the S. argenteus from cow milk samples with SCM. Data on the molecular characteristics, virulence genes and antibiograms of the Staphylococcus spp. obtained from the present study showed a wide spread and increasing trend of methicillin-resistance and multiple resistance to other antibiotics. This suggests that the “One Health” practice should be nurtured, not only at the dairy farm level, but also at the national or even the international levels through cooperation of different sectors (dairy farmers, veterinarians, medical and public health personnel and scientists) in order to effectively combat and control the spread of these pathogens.