Contamination Levels and Phenotypic and Genomic Characterization of Antimicrobial Resistance in Escherichia coli Isolated from Fresh Salad Vegetables in the United Arab Emirates

Abstract

Contaminated fresh produce has been identified as a vehicle for human foodborne illness. The present study investigated the counts, antimicrobial resistance profile, and genome-based characterization of Escherichia coli in 11 different types of fresh salad vegetable products (n = 400) sampled from retailers in Abu Dhabi and Dubai in the United Arab Emirates. E. coli was detected in 30% of the tested fresh salad vegetable items, with 26.5% of the samples having an unsatisfactory level (≥100 CFU/g) of E. coli, notably arugula and spinach. The study also assessed the effect of the variability in sample conditions on E. coli counts and found, based on negative binominal regression analysis, that samples from local produce had a significantly higher (p-value < 0.001) E. coli count than imported samples. The analysis also indicated that fresh salad vegetables from the soil-less farming system (e.g., hydroponic and aeroponic) had significantly (p-value < 0.001) fewer E. coli than those from traditional produce farming. The study also examined the antimicrobial resistance in E. coli (n = 145) recovered from fresh salad vegetables and found that isolates exhibited the highest phenotypic resistance toward ampicillin (20.68%), tetracycline (20%), and trimethoprim-sulfamethoxazole (10.35%). A total of 20 (13.79%) of the 145 E. coli isolates exhibited a multidrug-resistant phenotype, all from locally sourced leafy salad vegetables. The study further characterized 18 of the 20 multidrug-resistant E. coli isolates using whole-genome sequencing and found that the isolates had varying numbers of virulence-related genes, ranging from 8 to 25 per isolate. The frequently observed genes likely involved in extra-intestinal infection were CsgA, FimH, iss, and afaA. The β-lactamases gene blaCTX-M-15 was prevalent in 50% (9/18) of the E. coli isolates identified from leafy salad vegetable samples. The study highlights the potential risk of foodborne illness and the likely spread of antimicrobial resistance and resistance genes associated with consuming leafy salad vegetables and emphasizes the importance of proper food safety practices, including proper storage and handling of fresh produce.

Genomic Evaluation of Multidrug-Resistant Extended-Spectrum β-Lactamase (ESBL)-Producing Escherichia coli from Irrigation Water and Fresh Produce in South Africa: A Cross-Sectional Analysis

“…coli isolates harboring clinically significant bla CTX‑M genetic determinants, among others, have previously been reported in water and fresh produce samples, which correspond to the results from the current study. Currently, the most prevalent ESBL globally reported in clinical isolates, human and animal fecal matter, and the aquatic environment is bla CTX‑M‑15 . , The predominant β-lactamase resistance genes detected in the current study were bla CTX‑M‑14 (CTX-M Group 9) followed by bla CTX‑M‑15 (CTX-M Group 1), and in selected isolates, these genes were associated with insertion sequences.…”

“…Currently, the most prevalent ESBL globally reported in clinical isolates, human and animal fecal matter, and the aquatic environment is bla CTX-M-15 . 71,77 The predominant βlactamase resistance genes detected in the current study were bla CTX-M-14 (CTX-M Group 9) followed by bla CTX-M-15 (CTX-M Group 1), and in selected isolates, these genes were associated with insertion sequences. Specifically, in two isolates, bla CTX-M-15 was carried on the insertion sequence ISEc9, which corresponds to a previous study where E. coli was isolated from hospital patients in Nigeria.…”

Pathogenic E. coli in the Food Chain across the Arab Countries: A Descriptive Review

“…Generally, pathogenic E. coli is broadly classified into two major categories: diarrheagenic E. coli and extraintestinal pathogenic E. coli. The intestinal or diarrheagenic pathogenic strains of E. coli are rarely found among the intestinal flora of healthy mammals [18,21]. Based on the virulence factors, six different pathogenic classes of intestinal pathogenic E. coli have been identified, namely, enterotoxigenic E. coli (ETEC), enteropathogenic E. coli (EPEC), enterohemorrhagic E. coli (EHEC)/Shiga toxin-producing E. coli (STEC), enteroinvasive E. coli (EIEC), enteroaggregative E. coli (EAEC), and diffusely adherent E. coli (DAEC) [13,22].…”

Endogenous Bacteremia Caused by Intestinal Colonization of Carbapenem-Resistant Enterobacteriaceae (CRE) in Immunocompromised Children

“…Enterobacteriaceae is a family of bacteria that belongs to Gammaproteobacteria, which are members of the gut microbiota. They can harbor different virulence genes that will convert them to life-threatening pathogens for humans [ 2 , 3 ]. These bacteria are known as the cause of bacteremia, diarrhea, surgical site infections, pneumonia, and urinary tract infections in both hospitalized and non-hospitalized people in all age groups [ 4 , 5 ].…”