E. coli counts in vegetables from retailers in Abu Dhabi and Dubai

A new study by Ihab Habib, Rami H Al-Rifai, Mohamed-Yousif Ibrahim Mohamed, Akela Ghazawi, Afra Abdalla, Glindya Lakshmi, Neveen Agamy and Mushtaq Khan investigates E. Characterization of 11 different types of fresh salad vegetable products (n = 400) sampled from retailers in Abu Dhabi and Dubai, United Arab Emirates.

E. coli was detected in 30% of the fresh salad green items tested, with 26.5% of the samples having unacceptable E. coli levels (≥100 CFU/g), especially arugula and spinach. The study also assessed the effect of variability in sample conditions on E. coli counts and found, based on negative binomial regression analysis, that local produce samples had significantly higher E. coli counts than imported samples (p-value < 0.001).

The analysis also showed that fresh salad vegetables from soilless farming systems (eg, hydroponics and aeroponics) had significantly less E. coli (p-value < 0.001) than vegetables grown from conventional produce. The study also examined antimicrobial resistance in Escherichia coli (n = 145) recovered from fresh salad greens and found that isolates were resistant to ampicillin (20.68%), tetracycline (20%), and trimethoprim-sulfamethoxine Oxazole (10.35%) exhibited the highest phenotypic resistance).

A total of 20 (13.79%) of 145 E. coli isolates exhibited multidrug-resistant phenotypes, all from locally sourced leafy salad vegetables. The study further characterized 18 of 20 multidrug-resistant E. coli isolates using whole-genome sequencing and found that these isolates had varying numbers of virulence-associated genes, ranging from 8 to 25 per isolate. Common genes that may be involved in parenteral infection are CsgA, FimH, iss, and afaA. The β-lactamase gene blaCTX-M-15 was ubiquitous in 50% (9/18) of E. coli isolates identified from leafy salad vegetable samples.

The study highlights the potential risk of foodborne illness and the possible spread of antimicrobial resistance and resistance genes associated with consumption of leafy salad greens. It highlights the importance of proper food safety practices, including proper storage and handling of fresh produce.

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