The Emergence of Extended-Spectrum β-Lactamase Producing and Hybrid Pathotypes of Escherichia Coli Isolates from Diarrheic Human Cases: A New Public Health Concern in Iran

Abstract

Background: Intra-intestinal pathogenic strains of Escherichia coli are responsible for mild to severe gastrointestinal lesions, which are mediated by various virulence factors. In this study, we have focused on a comprehensive set of E. coli pathotypes, including STEC, EPEC, EHEC, ETEC, and some hybrid pathotypes including, STEC/ ETEC, EHEC/ ETEC, and EPEC/ ETEC.Methods: Totally, 467 stool samples were obtained from gastrointestinal patients during four years (2016 to 2020). Four pathotypes of E. coli (EPEC, ETEC, EHEC, STEC) were screened due to six virulence genes, including eae, stx1, stx2, st, and lt using the conventional PCR method. Finally, detected E. coli pathotypes were subjected to determine phenotypic and genotypic β-lactam resistance properties.Result: In this study 59/467 (12.63%) strains belonged four pathotypes including STEC (20/59; 50.8%), EPEC (11/59; 18.6%), ETEC (8/59 13.5%), EHEC (5/59; 8.4%) and three novel hybrid pathotypes including STEC/ETEC (3/59; 5%), EHEC/ETEC (1/59; 1.6%), and EPEC/ETEC (1/59; 1.6%). Totally 23/59 (38.9%) isolates were identified as ESBL-producing. Conclusion: Transmission of virulence and antibiotic resistance genes among E. coli strains lead to the emergence of antimicrobial-resistant hybrid pathogenic strains, which is an important health concern. According to food-born and fecal-oral transmission of these E. coli strains, standard methods should be performed to eliminate the possible contamination of food, equipment, and living environment to manure and feces.

Phylotypes and Pathotypes of Diarrheagenic Escherichia coli of Gastroenteritis

“…All DEC Pathotypes categorized according to molecular contents of some virulence genes: eae and bfpA for EPEC [12]; st1a, st1b and ltb1 for ETEC; aggR for EAEC; stx1 and stx2 for EHEC/STEC; ipaH for EIEC; daaD for DAEC [13]. Many studies revealed that, the most prevalent diarrheagenic E. coli were ETEC, EPEC, EAEC, AIEC, EHEC/STEC and DAEC [14][15][16][17]. Concern phylogroups of EPEC, the results gathered from 18 studies for 433 EPEC isolates revealed that: B1 compile (39.3%), A(23.3%), B2(18.2%), D(8.5%), (6.2%, 3.5% and 0.9%) for E, C and F phylogroups respectively (Table 2) [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35].…”