Detection, Virulence Gene Assessment and Antibiotic Resistance Pattern of O157 Enterohemorrhagic Escherichia coli in Tabriz, Iran

Isolation and Molecular Characterization of Enterotoxigenic Escherichia coli (ETEC) Strains From Industrial Dairy Farms of Hamedan, Iran

Background: Enterotoxigenic Escherichia coli (ETEC) is considered as one of the most common causes of infectious diarrhea in calves, infecting animals during the first week of age. The secretory diarrhea is attributed to the virulence factors of ETEC strains mainly including heat stable toxin (STa), as well as F5 (K99) and F41 fimbriae. Objectives: The present study was undertaken to investigate ETEC infection in neonatal calves of industrial dairy farms of Hamedan, Iran. Additionally, it was undertaken to investigate the genotypic screening of virulence genes in enterotoxigenic E. coli isolated from from dairy farms calves of Hamedan county. Materials and Methods: A total of 120 rectal swab samples were collected from healthy and diarrheic calves at one week of age belonging to eight farms. Conventional bacteriological methods, multiplex PCR, and antibiotic susceptibility test of the ETEC isolates were performed. Results: Nine E. coli isolates were found to be ETEC strains, carrying STa enterotoxin along with F5 and/or F41 fimbriae as the indicators of ETEC cells. Additionally, antibiotic susceptibility test of the ETEC isolates revealed that all of them were sensitive to trimethoprim-sulfamethoxazole, ciprofloxacin, and enrofloxacin, whereas complete resistance was observed against amoxicillin-clavulanic acid (100%) and polymyxin B (100%). The present study, conducted for the first time in Hamedan, indicated a prevalence of 7.5% for Enterotoxigenic Escherichia coli in the examined animals. Conclusion: Regarding economic losses of the infection in claves as well as the zoonotic nature of ETEC cells, it is recommended that measures should be taken, such as immunization of pregnant cows prior to the delivery, feeding of adequate colostrum to newborn calves at the right time, and adherence to hygiene practices on the farms to prevent and/or reduce the incidence of diarrhea cases caused by infection with these bacteria.

Prevalence and virulence gene profiles of Escherichia coli O157 from cattle slaughtered in Buea, Cameroon

Background

Escherichia coli O157 is an emerging foodborne pathogen of great public health concern. It has been associated with bloody diarrhoea, haemorrhagic colitis and haemolytic uremic syndrome in humans. Most human infections have been traced to cattle and the consumption of contaminated cattle products. In order to understand the risk associated with the consumption of cattle products, this study sought to investigate the prevalence and identify virulence genes in E. coli O157 from cattle in Cameroon.

Method

A total of 512 rectal samples were obtained and analysed using conventional bacteriological methods (enrichment on modified Tryptone Soy Broth and selective plating on Cefixime-Tellurite Sorbitol Mac-Conkey Agar) for the isolation of E. coli O157. Presumptive E. coli O157 isolates were confirmed serologically using E. COLIPRO^TM O157 latex agglutination test and molecularly using PCR targeting the rfb gene in the isolates. Characterisation of the confirmed E. coli O157 strains was done by amplification of stx1, stx2, eaeA and hlyA virulence genes using both singleplex and multiplex PCR.

Results

E. coli O157 was detected in 56 (10.9%) of the 512 samples examined. The presence of the virulence genes stx2, eaeA and hylA was demonstrated in 96.4% (54/56) of the isolates and stx1 in 40 (71.4%) of the 54. The isolates exhibited three genetic profiles (I-III) with I (stx1, stx2, eaeA and hlyA) being the most prevalent (40/56; 71.4%) while two isolates had none of the virulence genes tested.

Conclusion

A proportion of cattle slaughtered in abattoirs in Buea are infected with pathogenic E. coli O157 and could be a potential source of human infections. We recommend proper animal food processing measures and proper hygiene be prescribed and implemented to reduce the risk of beef contamination.

An overview of diarrheagenic Escherichia coli in Iran: A systematic review and meta-analysis

BACKGROUND

Diarrheagenic Escherichia coli (DEC) is a common enteric pathogen that causes a wide spectrum of gastrointestinal infections, particularly in developing countries. This is a systematic review and meta-analysis to determine the prevalence of DEC in various geographical regions in Iran.

MATERIALS AND METHODS

English (PubMed, Web of Science, Scopus, Embase, Cochrane Library, and Google Scholar) and Persian (IranMedex, SID, Magiran, and Iran Doc) databases were comprehensively searched from January 1990 to April 2017. Study selection and data extraction were performed by two independent reviewers. After assessing heterogeneity among studies, a random effects model was applied to estimate pooled prevalence. Data analyses were done with the Stata software (version 12.0). This meta-analysis was registered with PROSPERO, number CRD42017070411.

RESULTS

A total of 73 studies with 18068 isolates were eligible for inclusion within the meta-analysis. The results of random effects model showed that the most prevalent DEC pathotypes were enterotoxigenic E. coli (ETEC) (16%; 95% confidence interval [CI]: 11%-23%), enteroaggregative E. coli (11%; 95% CI: 8%-15%), atypical enteropathogenic E. coli (EPEC) (11%; 95% CI: 8%-14%), Shiga toxin-producing E. coli (9%; 95% CI: 6%-13%), diffuse adherent E. coli (6%; 95% CI: 6%-12%), enteroinvasive E. coli (4%; 95% CI: 2%-6%), and typical EPEC (3%; 95% CI: 1%-5%).

CONCLUSION

This study showed that DEC infections in the Iranian population have low frequency. Our data suggest that the ETEC pathotype can be regarded as one of the most important etiological agents of diarrhea in this country. However, the prevalence of DEC pathotypes is diverse in different regions of Iran.

The frequency of shiga-like toxin (stx1 and stx2) and EHEC-hlyA in food by multiplex PCR

Aim: The aim of the present study was to determine the frequency of shiga-like toxin (stx1 and stx2) and drug resistance profiles food-borne Escherichia coli O157:H7 in Hatay province, Turkey. Methods: The presence of the virulence genes (stx1, stx2, hlyA) in a total of 150 E.coli isolates were studied with multiplex PCR. Results: A total of 327 salad samples were analyzed. E. coli O157:H7 was detected in 150 (45.8 %) out of 327 analyzed samples. Of these 150 isolates, the presence of hly-A gene was detected in 32 (21.3%) E.coli isolates. A total of five (15.6%) isolates in this 32 hlyA positive isolates had stx2 gene, two (6.3%) of them had stx1 gene and one (3.1%) of the isolates was found to be positive for both stx1 and stx2 genes. It was found that all E.coli O157:H7 isolates were resistant to erythromycin. While the highest rate of antibiotic resistance was observed for ampicillin (68.8%), no antibiotic resistance against cefuroxime, ciprofloxacin and cephaperasone was identified. Conclusions: The results obtained in our province showed that E.coli strains isolated from salad samples were found to have some important virulence genes such as stx1, stx2, and hlyA. The stx2 frequency was found to be higher than stx1 frequency. Also, it was observed that there was not any significant correlation between drug resistance profiles and presence of toxin genes in E.coli O157:H7 strains. As a result, increasing frequency of STEC O157 serotype among foodborne pathogens is a growing public health problem.