Irrigated Vegetables: A Potential Route for the Dissemination of Extended-Spectrum Beta-Lactamase- and AmpC-Producing Enterobacteriaceae in Lagos, Nigeria

Antibiotic resistance remains a global public health concern, and the prevalence of Enterobacteriaceae species that harbor antibiotic resistance genes (ARGs) is on the rise. The aim of this study was to assess the distribution of extended-spectrum beta-lactamase (ESBL)/AmpC-producing Enterobacteriaceae in vegetables cultivated on irrigated farms in Lagos, Nigeria. A total of 257 samples, including vegetable samples, irrigation water, and soil, were collected from five farms within the city. Standard microbiological and molecular biology methods were used for the isolation and characterization of bacterial genera within Enterobacteriaceae and the detection of ARGs. Antibiotic susceptibility testing was conducted using the Kirby-Bauer disc diffusion method, and ESBL production was determined by the double-disk synergy test. Fifty-eight bacterial strains were isolated from the samples, of which 52 (90%) belonged to the family Enterobacteriaceae . Ten genera from this family were represented among obtained isolates, with Klebsiella species and Escherichia fergusonii being most prevalent. In total, 85% and 52% of these isolates were resistant to amoxicillin–clavulanic acid and ceftazidime, respectively. Sixty-five percent of these isolates were multidrug-resistant (MDR), with 56% and 46% testing positive for ESBL and AmpC production, respectively. Some of the MDR isolates had Multiple Antibiotic Resistance Index (MARI) ranging from 0.4 to 0.8. bla SHV was the dominant ESBL encoding gene detected, while bla AmpC was detected in only 4% of isolates. Plasmids ranging in size from 2.6 to 20.35 kb were detected in some of the MDR Enterobacteriaceae isolates. The presence of MDR Enterobacteriaceae in the food chain is of public health significance, highlighting the need for continuous surveillance.