Prevalence and characterization of extended-spectrum β-lactamase-producing and isolated from raw vegetables retailed in Southern Thailand.

Background: The increasing prevalence of broad-spectrum ampicillin-resistant and third-generation cephalosporin-resistant , particularly and , has become a global concern, with its clinical impacts on both human and veterinary medicine. This study examined the prevalence, antimicrobial susceptibility, and molecular genetic features of extended-spectrum β-lactamase (ESBL)-producing and isolates from 10 types of raw vegetables.

Methods: In total, 305 samples were collected from 9 markets in Nakhon Si Thammarat, Thailand, in 2020.

Results: ESBL-producing and isolates were found in 14 of the 305 samples obtained from 7 out of 10 types of vegetables (4.6% of the total). Further, 14 ESBL-producing ( = 5/14) and isolates ( = 9/14) (1.6% and 3.0%, respectively) were highly sensitive to β-lactam/carbapenem antibiotics (imipenem, 100%). ESBL-producing ( = 4) and isolates ( = 8) were also sensitive to non-β-lactam aminoglycosides (amikacin, 80.00% and 88.89%, respectively). ESBL producers were most resistant to β-lactam antibiotics, including ampicillin (85.71%) and the cephalosporins cefotaxime and ceftazidime (64.29%). The most frequently detected gene in ESBL-producing and was . However, two ESBL-producing isolates also carried three other ESBL-encoding variants, , , , which may be due to their association with food chains and humans.

Discussion: Indeed, our results suggest that raw vegetables are an important source of ESBL-resistant and , which are potentially transmittable to humans via raw vegetable intake.