eaeA Virulence Genes Research Articles

Characterization of enterohemorrhagic Escherichia coli from diarrhoeic patients with particular reference to production of Shiga-like toxin

Enterohemorrhagic Escherichia coli (EHEC) is a subtype of pathogenic E. coli that causes diarrhea or hemorrhagic colitis in humans, which can progresses to hemolytic uremic syndrome (HUS), a leading cause of acute renal failure in children, and morbidity and mortality in adults. Stool samples (n = 273) of patients (1 day-40 years old) suffered from bloody diarrhea and abdominal cramps, were examined bacteriologically and molecularly for the presence and pathogenicity of EHEC with phylogenetic analysis of the obtained stx1, stx2, and eaeA virulence genes’ sequences. Overall, 71 (26.01%) E. coli isolates were identified as EHEC with the following serogroupes: O1:H11 (3), O128:H2 (9), O26:H11 (6), O157:H7 (3), O25:H2 (7), O145:H328 (2), O125:H6 (9), O86:H8 (5), O18:H15 (11) and untypable (16). The highest isolation rate were in samples belonged to infants below two years old (42.25%). Antimicrobial susceptibility testing showed that all isolates were highly sensitive to ciprofloxacin, nitrofurantoin, gentamycin, imipenem and vancomycin (100% each), however, they were resistant to ampicillin, cephalexin, penicillin and tetracycline (100% each). In-vitro pathogenicity testing of the isolates revealed that 67 (94.37%) isolates were positive for Congo red test, 47 (66.20%) isolates possessed P fimbriae (MRHA) and 17 (23.94%) possessed type 1 fimbriae (MSHA). Moreover, 46 (64.79%) isolates exhibited hemolysis and 42 (59.15%) isolates showed distinct cytopathic effect to Vero cells. Molecular detection of enterohemorrhagic E. coli (EHEC) pathotype virulence genes, confirmed the presence of stx1 gene in O157:H7 (MA2), O26:H11, O145:H328 and O125:H6 serogroups; stx2 gene in (O157:H7 (MA1), O128:H2 and O25:H2; while all serogroups except (O125:H6) carried the eaeA intimin virulence gene. A phylogenetic tree, based on the nucleotide sequences of toxin-encoding genes, demonstrates that Shiga toxin E. coli (STEC) isolates have considerable genetic variation and belong to various phylogenetic groupings.

Evaluation of stx1, stx2, hlyA, and eaeA Virulence Genes in Escherichia coli O157:H7 Isolated from Meat (Beef and Mutton) in Hamedan, Iran, During 2015-2016

Background and Objectives: Consuming raw or undercooked cattle meat is the most common transmission way of infection with Escherichia coli O157:H7. The present study aimed to identify virulence genes stx1, stx2, hlyA, and eaeA in E. coli isolated from meat samples (beef and mutton) in Hamedan during 2015 and 2016. Materials and Methods: For this purpose, the swabs were randomly taken from 160 meat samples including 80 beef samples and 80 mutton samples from butcher shops. Isolation and identification of E. coli cells were conducted by culturing the swab samples on MacConkey agar and Eosin methylene blue agar media. Then, the identity of the suspected E. coli O157:H7 colonies was investigated by a multiplex PCR assay and eventually, the isolates were evaluated for the presence of stx1, stx2, hlyA, eaeA virulence genes. Results: The results showed that out of 160 cultured samples on the selective media, 60 samples (37.5%) were contaminated with E. coli. O157:H7, O157, and H7 strains were identified using PCR, among which only E. coli O157:H7 possessed all four virulence factor encoding genes. Conclusion: The results of this study showed that beef could be a reservoir for E. coli O157:H7, and it may be involved in the transmission of this pathogen to humans.

Prevalence and Antimicrobial Characteristics of Shiga Toxin-Producing Escherichia coli Isolates from Pork in Korea.

Shiga toxin-producing Escherichia coli (STEC) strains are important food-borne pathogens that can be transmitted through the consumption of food products derived from pigs. Moreover, antimicrobial resistance in STEC has been a matter of increasing concern. The aim of this study was to investigate the prevalence and antimicrobial characteristics of STEC isolates from pork in Korea. We isolated 131 isolates of E. coli from 334 pork samples collected from slaughterhouses and retail markets from 2008 to 2009. Among the 131 isolates, 6 (4.58%) were confirmed to belong to 6 different serotypes of STEC. All six STEC isolates contained stx1 and eaeA virulence genes, and four of them additionally carried the hly gene. The minimum inhibitory concentration (MIC) of 15 antibiotics (amoxicillin/clavulanic acid, ampicillin, cephalothin, cefoxitin, ceftiofur, gentamicin, neomycin, streptomycin, nalidixic acid, ciprofloxacin, colistin, chloramphenicol, florfenicol, tetracycline and sulfamethoxazole/trimethoprim) toward the STEC isolates was determined. As a result, three strains were associated with high MICs for florfenicol and chloramphenicol (64 μg/mL). Furthermore, all three strains were found to contain the florfenicol-resistant gene (floR) but not the chloramphenicol-resistant gene (cat). Sequence alignment and BLAST analysis of the polymerase chain reaction products of the floR gene indicated that they contained sequences with homology to the floR gene of E. coli or Salmonella enterica serovar, Heidelberg. This is the first report on the detection of floR in STEC isolated from pork obtained from retail markets in Korea.

Detection and Importance of Some Pathogenic Bacteria in Psittascine Birds with Special Reference to the Virulence Genes

Psittascine birds are potential carriers and/or transmitters of some pathogenic bacteria, which have an important impact on human health. The scope of this study was to survey, isolate and identify some pathogenic bacteria in psittascine birds with special regard to plasmid detection of some virulent and resistance genes. A total of 120 samples (85 from different birds, 35 samples from their surrounding) were collected for microbiological investigations. All isolates were submitted to antimicrobial susceptibility testing and discussed in details. E. coliwas the predominant isolate in all examined birds (34.11%) followed by Staphylococcus spp . (32.9%) and Salmonella spp . (12.9%). E. coliof O78 was the most prevalent serotype detected in all samples also; Salmonella Typhymurium was the most frequent serovar in all recovered Salmonella spp. isolates. Plasmid detection of crl and eaeAvirulence genes of E. coliisolates were found in (100% and 33.3%, respectively). Also, all examinedisolates of Salmonella spp . and Staphylococcus spp . showed the presence of (invA, stn and fimH) and (clfAand icaA) virulence genes in (100%, for each), respectively. Meanwhile, screening for antibiotic resistance genes (dfrA, tetA, blaTEM, qnrA, norA and blaZ) of E. coli, Salmonella spp . and Staphylococcus spp., respectivelywere detected on all relative plasmid profiles (100%, for each). In conclusion, several bacterial pathogens were isolated from psittascine birds so, it is recommended to apply good biosecurity management and good hygiene with competent and quality veterinary care in birds/ pets breeding, with preventive guidelines. Also, due to the zoonotic nature of some bacteria, it is very important that pet bird owners should be trained well to practice good hygiene when handling / breeding their pets to limit the risk of zoonotic diseases.

Detection of E. coli in Nile Tilapia from retail in Gharbiya Governorate

The presence of E. coli in fresh-marketed fish indicates recent contamination and is usually attributed to infected handlers or storage on contaminated ice. E. coli may be transmitted to human during handling of fish or consumption of raw or under cooked fish. Human infection (foodborne illnesses) range from mild diarrhea to life threatening hemorrhagic colitis (HC), haemolytic uremic syndrome (HUS). In this study, 200 fish samples from gills, musculature, surface and intestine, 100 water samples and 100 hand swaps from sellers’ hand were collected from Kafrelzyate and Tanta retail markets in Gharbiya. The samples were examined for the presence of E. coli. Forty-four samples (8 gills, 3 musculature, 8 surface, 9 intestine, 9 water and 7 hands of sellers) were positive to E. coli. The identification was carried out by both biochemical methods and PCR. The 44 isolates were tested for antimicrobial resistance using 10 antimicrobial discs and the results revealed multiple antimicrobial resistance. Serological identification of the isolates showed the presence of O44 (15.9 %), O125 (20.4 %), O172 (13.6 %), O103 (6.8 %) and O119 (18.1 %). The stx1, stx2 and eaeA virulence genes were detected by PCR in the isolates.

PCR Detection of Shiga Toxins, Enterohaemolysin and Intimin Virulence Genes ofEscherichia coliO157:H7 Strains Isolated from Faeces of Anatolian Water Buffaloes in Turkey

The aim of this study was to detect Shiga toxins (stx1 and stx2), enterohaemolysin (EhlyA) and intimin (eaeA) virulence genes of 11 Escherichia coli O157:H7 strains isolated from faecal samples of 300 clinically healthy Anatolian water buffaloes by PCR. Multiplex PCR was used for the detection of stx1 and stx2, and singleplex PCRs were used for the detection of EhlyA and eaeA virulence genes respectively. A total of three (27.3%) strains were determined to harbour both of the stx1 and stx2 genes, of these, one (9.1%) only harboured these two genes alone, one (9.1%) also contained the EhlyA gene and one (9.1%) additionally contained the EhlyA and the eaeA genes. EhlyA gene was obtained from eight (72.7%) strains, six (54.5%) of these were alone. eaeA gene was positive in only one (9.1%) strain. Only one (9.1%) of the 11 E. coli O157:H7 strains harboured all the four virulence genes. Two (18.2%) of the isolates had none of the virulence genes. Enterohaemolysin was found to be the most common virulence factor. In conclusion, the virulence factors of E. coli O157:H7 strains isolated from the faeces of Anatolian water buffaloes were investigated and detected for the first time in Turkey.