Extended spectrum ß-lactamase and AmpC-producing Enterobacteriaceae in raw vegetables

Antibiotic resistance in bacteria is a global problem exacerbated by the dissemination of resistant bacteria via uncooked food, such as green leafy vegetables. The attribution of fresh produce to the overall community-associated exposure of humans to ESBL- or AmpC- producing. The aim of the current study was carried out to assess the of extended spectrum β-lactamase and AmpC type β-lactamase in Enterobacteriaceae isolated from fresh vegetables sold in the local markets of Modena town. Methods: A total of 80 samples comprising carrot, spring onion, tomatoes, arugula, chicory, endive and frisee salad were processed microbiologically to isolate Enterobacteriaceae. The vegetables were mostly obtained from supermarkets. Species identification and antimicrobial susceptibility testing were carried out using the Vitek 2 system and the AST-GN041 card (bioMérieux). Phenotypic testing by using the Double Synergy Differential Test (DSDT) for ESBL/AmpC-positive strains was confirmed by PCR and DNA sequence analysis. The localization of β-lactamase genes was established by conjugation experiments. Results: Overall, of the 160 analyzed strains ESBLs/AmpC were detected in 20 isolates (12,5%) for the double-disk synergy test. The major ESBL determinant was the CTX-M type (7,5% isolates) and two SHV (1,25%). DHA and ACC (2,5 % of isolates) were AmpC-β lactamases type. Additionally, we identified newly recognized ESBL blaRAHN-2 sequences from Rahnella aquatilis. The conjugation has demonstrated the transmissibility of this resistance determinant. Conclusion: In conclusion, we report a highter and a low prevalence of ESBL and AmpC β-lactamase determinants respectively mostly in arugula and frisee salad . Public health risks associated with exposure to ESBL- and AmpC-producing bacteria through consumption of uncooked fresh produce are diverse. They range from occasional ingestion of 3GC-resistant opportunistic pathogens which may result in difficult-to-treat infections, to frequent ingestion of relatively harmless ESBL producing environmental bacteria that may therewith constitute a continuously replenished intestinal reservoir facilitating dissemination of ESBL genes to (opportunistic) pathogens.