Characterization of virulence genes of non-O157 Shiga toxin-producing Escherichia coli isolates from two provinces of Iran (original) (raw)
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Journal of Clinical Microbiology, 2002
Strains of Shiga toxin-producing Escherichia coli (STEC) have been associated with outbreaks of diarrhea, hemorrhagic colitis, and hemolytic-uremic syndrome in humans. Most clinical signs of disease arise as a consequence of the production of Shiga toxin 1 (Stx1), Stx2 or combinations of these toxins. Other major virulence factors include enterohemorrhagic E. coli hemolysin (EHEC hlyA ), and intimin, the product of the eaeA gene that is involved in the attaching and effacing adherence phenotype. In this study, a series of multiplex-PCR assays were developed to detect the eight most-important E. coli genes associated with virulence, two that define the serotype and therefore the identity of the organism, and a built-in gene detection control. Those genes detected were stx 1 , stx 2 , stx 2c , stx 2d , stx 2e , stx 2f , EHEC hlyA , and eaeA , as well as rfbE , which encodes the E. coli O157 serotype; fliC , which encodes the E. coli flagellum H7 serotype; and the E. coli 16S rRNA, whi...
Gastroenterology and Hepatology From Bed to Bench, 2018
Aim: The present study was conducted to detect the occurrence, serogroups, virulence genes and phylogenetic relationship of shiga toxin-producing Escherichia coli (STEC) in human, clave and goat in Kerman (southeast of Iran). Background: STEC have emerged as the important foodborne zoonotic pathogens causing human gastrointestinal disease and confirming the risk to public health. Methods: A total of 671 fecal samples were collected from diarrheic patients (n=395) and healthy calves (n=156) and goats (n=120) and screened for the presence of stx gene. Furthermore, the prevalence of stx1 and stx2 variants, serotypes (O157, O145, O103, O26, O111, O91, O128, and O45), phylogenetic groups and the presence of ehxA, eae, hylA, iha and saa virulence genes were studied. Results: Prevalence of STEC in human diarrheic isolates was 1.3% (5 isolates), in claves was 26.3% (41 isolates) and in goats was 27.5% (33 isolates). stx1 gene was the most prevalent variant and detected in 75 isolates. Furth...
Global Veterinaria, 2009
Shiga toxin-producing Eschericia coli are diverse organisms inducing sever gastrointestinal and systematic diseases recognized worldwide. Ten serogroups were isolated, morphologically identified and biochemically characterized from 281 samples (fecal swabs and internal organs) of diarrheic field cases collected from cattle and ostrich private farms. Haemolysis, enterocytotoxicity, pathogenicity and antibiogram patterns were determined. All isolates were Stxs producers according to the cytopathic effects noticed in inoculated Vero cells monolayers with CD activity titers calculated 32 (O1 and bovine O157), 8 (O8 and O25), 64 (O20), 50 4 (O78) and 128 (O127, O146, O153, Ostrich O157) CD /100 µl. Dominant protein bands with apparent 50 molecular masses of 106 to109 kDa, 80-83 kDa, 54-56 kDa, 41 kDa, 37 kDa, 32 kDa, 26-25 kDa, 22 kDa and 7.8 kDa were separated by SDS-PAGE of E coli cultures supernatants. These bands were not uniformly expressed nor equally presented by all serotypes under study. In addition, 346 bp stx2 specified sequence were amplified by PCR in five serotypes only. None of the isolates were positive for stx1 coding sequences. It is clearly noticed that some serogroups are more virulent than others. Virulence properties depend on less characterized factors than Stx1 and Stx2 which has been proved from profiles of secretory proteins. It was concluded that STEC virulence is multifactorial process. However, Shiga toxins production, in particular Stx2, is a minimum requirement. Other secreted virulence proteins such as EspA (26-25 kDa), EspB (37 kDa), EspD (41 kDa), EspE (80-83 kDa), EspP (106-109 kDa) and Clostridium difficile-like toxins (32 kDa) are putative candidates involved in disease production their contribution in pathogenicity of isolated strains should be identified on both structural and functional levels.
Molecular characterisation of Shiga toxin-producing Escherichia coli O157 strains isolated in Poland
Research in Veterinary Science, 2001
Ten Escherichia coli O157 strains isolated from cattle and children in Poland were investigated by the use of molecular biological methods. All strains possessed the intimin and enterohaemolysin genes and harboured the genetic determinants for Stx2 toxin (five isolates), Stx1 toxin (two strains) or both (three isolates). The genetic relatedness of the strains was examined by restriction fragment length polymorphism (RFLP) of chromosomal DNA digested with Xbal and Notl. Nine closely related RFLP patterns were observed. Comparison of bovine and human E coli O157 isolates based on the analysis of Xbal and Notl digested profiles showed that all strains belonged to one genetic cluster. These results indicate that cattle must be considered as a possible source of human E coli O157 infection in Poland.
Journal of medical microbiology, 2000
Three Shiga toxin (Stx)-producing Escherichia coli (STEC) strains from patients with diarrhoea were identified, each of which contained three distinct stx genes (stx1, stx2 and stx2c). The strains belonged to the serotypes O52:H19, O75:H- and O157:H- and harboured eae and EHEC-hly sequences. Colony-blot immunoassay was used to demonstrate that both major types of Stx were expressed. The association of stx genes with either phage or phage DNA was demonstrated in all three strains. Isolated phage DNA from all strains contained stx1 sequences, but stx2 sequences were found only in phage DNA of two of these strains. The presence of three distinct stx genes may enhance the virulence of STEC strains and should be monitored. The observations demonstrate not only the potential of stx genes to spread within different serotypes, but also their capacity to accumulate within a single strain.
It has been demonstrated that certain E. coli isolates produced a toxin, which was initially called verotoxin because of its distinct effect on vero cells 1. This family of toxins was subsequently also called Shiga-like toxins (SLT), and more recently Shiga toxins (Stx), because of the close relation to the Stx of Shigella dysenteriae type 1. Background & objectives: Verotoxigenic Escherichia coli are important serotypes of enterohaemorrhagic E. coli (EHEC) subgroup that cause attaching and effacing lesions in enterocytes by producing verotoxins or shiga-like toxins resulting in haemorrhagic colitis (HC) and haemolytic uremic syndrome (HUS). The aim of this study was to detect these serotypes specially E. coli O157:H7 in stool samples of patients with diarrhoea and identification of virulence genes (STX1, STX2, Hly and EAE) in Shahrekord-Iran area using PCR technique.
Occurrence, serotypes and virulence genes of non-O157 Shiga toxin producing Escherichia coli
This study determined the prevalence, serotypes and virulence genes distribution of non-O157 Shiga toxin-producing Escherichia coliin meat products collected from butchers shops and supermarkets in Mansoura city, Egypt. We have characterized 18 non-O157 STEC strains among the identified 100E. coli isolates recovered from the examined 87 meat product samples. The prevalence of non-O157 STEC strains in fresh beef, ground beef and beef burger samples were 11.1% (3/27), 16.7% (5/30), and 33.3% (10/ 30), respectively. The eighteen non-O157 STEC isolated strains were serotyped into seven (38.9%) O111:H8, six (33.3%) O26:H11, two (11.1%) O111:He, and one (5.56%) for each of O55:H7, O126:H5 and O128:H2. PCR assays for different virulence genes showed that nine (50%), eleven (61.1%), and nine (50%) strains carry stx1,stx2, andeaegenes, respectively. The distribution of shiga toxin genes among the isolated strains indicated that seven (38.9%) strains harbored stx1 only, nine (50%) strains harboredstx2 only, and two (11.1%) strains harbored bothstx1 andstx2. Theeaegene was present in association with five (27.8%), three (16.7%), and one (5.6%) strains that harboredstx1 only,stx2 only, and bothstx1 and stx2, respectively. This study concluded that the examined meat products, particularly beef burger, consumed in Egypt are considerably contaminated with a variety of non-O157 STEC se
BMC Microbiology, 2008
Background: Shiga toxin-producing Escherichia coli (STEC) is an important cause of bloody diarrhoea (BD), non-bloody diarrhoea (NBD) and the haemolytic uraemic syndrome (HUS). In Argentina and New Zealand, the most prevalent STEC serotype is O157:H7, which is responsible for the majority of HUS cases. In Australia, on the other hand, STEC O157:H7 is associated with a minority of HUS cases. The main aims of this study were to compare the phenotypic and genotypic characteristics of STEC O157 strains isolated between 1993 and 1996 from humans in Argentina, Australia and New Zealand, and to establish their clonal relatedness. Results: Seventy-three O157 STEC strains, isolated from HUS (n = 36), BD (n = 20), NBD (n = 10), or unspecified conditions (n = 7) in Argentina, Australia and New Zealand, were analysed. The strains were confirmed to be E. coli O157 by biochemical tests and serotyping. A multiplex polymerase chain reaction (PCR) was used to amplify the stx 1 , stx 2 and rfb O157 genes and a genotyping method based on PCR-RFLP was used to determine stx 1 and stx 2 variants. This analysis revealed that the most frequent stx genotypes were stx 2 /stx 2c (vh-a) (91%) in Argentina, stx 2 (89%) in New Zealand, and stx 1 /stx 2 (30%) in Australia. No stx 1-postive strains were identified in Argentina or New Zealand. All strains harboured the eae gene and 72 strains produced enterohaemolysin (EHEC-Hly). The clonal relatedness of strains was investigated by phage typing and pulsed-field gel electrophoresis (PFGE). The most frequent phage types (PT) identified in Argentinian, Australian, and New Zealand strains were PT49 (n = 12), PT14 (n = 9), and PT2 (n = 15), respectively. Forty-six different patterns were obtained by XbaI-PFGE; 37 strains were grouped in 10 clusters and 36 strains showed unique patterns. Most clusters could be further subdivided by BlnI-PFGE. Conclusion: STEC O157 strains isolated in Argentina, Australia, and New Zealand differed from each other in terms of stx-genotype and phage type. Additionally, no common PFGE patterns were found in strains isolated in the three countries. International collaborative studies of the type reported here are needed to detect and monitor potentially hypervirulent STEC clones.
African journal of microbiology research
Shiga toxin producing Escherichia coli (STEC) is recognized as important food borne pathogen, responsible for sporadic cases of serious outbreaks worldwide. The morbidity and mortality associated with several recent outbreaks due to STEC have highlighted the threat this organism poses to public health. This study was conducted to identify and characterize the virulence traits and antibiotic resistance of enterohaemorrhagic E. coli from different sources, between September 2008 and October 2009. A total of 384 samples from human, animal and environmental sources were collected from different locations in Ismailia, Egypt. E. coli isolates (n = 283) were identified by conventional microbiology culture and were phenotypically characterized using biochemical and motility tests. Multiplex PCR (mPCR) was applied for the detection of virulence genes (stx1, stx2, eaeA and EHEC hlyA). From the overall number of E. coli isolates, 31.4% (89/283) were isolated from stools of humans with diarrhea...
Virulence genes of Shiga toxin-producing Escherichia coli isolated from food, animals and humans
International Journal of Food Microbiology, 1998
The presence of virulence genes, encoding enterohemorrhagic Escherichia coli (EHEC)-hemolysin (EHEC-hlyA), intimin (eae), and Shiga toxins 1 (stx1) and 2 (stx2), in 178 isolates of pathogenic E. coli, was determined using the polymerase chain reaction with primers specific for each virulence gene. The tested organisms were 120 isolates of E. coli O157:H7 from human patients, cattle, sheep and foods, 16 non-O157:H7 EHEC isolates from patients suffering from hemorrhagic colitis or hemolytic uremic syndrome, 15 non-O157:H7 Shiga toxin-producing E. coli (STEC) isolates from cattle and foods, 26 isolates of enteropathogenic E. coli (EPEC), enteroinvasive E. coli (EIEC) and enterotoxigenic E. coli (ETEC), and an E. coli K12 strain. Results revealed that all isolates of O157:H7 carried EHEC-hlyA, eae, and one or both stx genes; 15 of the 16 non-O157:H7 EHEC isolates had EHEC-hlyA, but all possessed eae and one or both stx genes; only seven of the 15 non-O157 STEC isolated from cattle and foods contained both EHEC-hlyA and eae genes. The EPEC, EIEC, ETEC, and the E. coli K12 strain did not carry these virulence genes, except eight EPEC isolates were positive for eae. Results suggest that a combination of EHEC-hlyA and eae genes could serve as markers to differentiate EHEC from less pathogenic STEC, and other pathogenic or non-pathogenic E. coli.