Abstract
Contamination of retail foods with foodborne pathogens, particularly the antimicrobial resistant ones, poses a persistent threat to human health. There is a dearth of information about the overlapping Escherichia coli (E. coli) lineages circulating among retail foods and humans in Egypt. This study aimed to determine the clonal diversity of 120 E. coli isolates from diarrheic patients (n = 32), retail chicken carcasses (n = 61) and ground beef (n = 27) from Mansoura, Egypt using pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST). Simpson’s index of diversity was calculated to compare the results of both typing methods. Antimicrobial resistance phenotypes, genotypes and phylogrouping of the isolates were also determined. Higher frequencies of antimicrobial resistance were found among chicken isolates compared to beef and human isolates; regardless of isolate source, the predominant antimicrobial resistances were found against ampicillin (87/120, 72.5%), tetracycline and sulfisoxazole (82/120, 68.3%, each), and streptomycin (79/120, 65.8%). None of the isolates displayed resistance to meropenem. The prevalent genes detected were tetA (64.2%), blaTEM (62.5%), sul1 (56.7%), floR (53.3%), sul2 (50%), strB (48.3%) and strA (47.5%) corresponding with resistance phenotypes. Alarmingly, blaCTX was detected in 63.9% (39/61) of chicken isolates. The majority of E. coli isolates from humans (90.6%), beef (81.5%) and chicken (70.5%) belonged to commensal phylogroups (A, B1, C). Using PFGE analysis, 16 out of 24 clusters (66.7%) contained isolates from different sources at a similarity level ≥75%. MLST results assigned E. coli isolates into 25, 19 and 13 sequence types (STs) from chicken, human and beef isolates, respectively. Six shared STs were identified including ST1011, ST156, ST48, ST224 (chicken and beef), ST10 (human and chicken) and ST226 (human and beef). Simpson’s index of diversity was higher for MLST (0.98) than PFGE (0.94). In conclusion, the existence of common genetic determinants among isolates from retail foods and humans in Egypt as well as the circulation of shared STs indicates a possible epidemiological link with potential zoonotic hazards.
Highlights
Escherichia coli (E. coli), a member of Enterobacteriaceae that inhabits the gastrointestinal tract, is divided into commensal and pathogenic strains that are capable of producing infections in humans and animals [1]
According to World Health Organization (WHO), many European countries and the US banned the use of antimicrobials for animal growth promotion, antimicrobials that are classified as critically important antimicrobials for treatment of human infections [8]
This is especially true considering the increase in antimicrobial resistance and the possibility of dissemination of resistance traits, especially those mediated by mobile genetic elements (MGE) through the food chain to humans [11,18,19]
Summary
Escherichia coli (E. coli), a member of Enterobacteriaceae that inhabits the gastrointestinal tract, is divided into commensal and pathogenic strains that are capable of producing infections in humans and animals [1]. In food-producing animals, both commensal and pathogenic strains of E. coli are able to contaminate meat, even in facilities with high standards, with a subsequent potential hazard to humans. The ever-increasing range of antimicrobial resistance in food-producing animals is a global problem. This phenomenon stems from the indiscriminate use of antimicrobials in treatment of animal infections as well as antimicrobial administration in sub-therapeutic doses for prophylaxis and growth promotion [4,5]. According to World Health Organization (WHO), many European countries and the US banned the use of antimicrobials for animal growth promotion, antimicrobials that are classified as critically important antimicrobials for treatment of human infections [8]
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