Co-Presence of Antibiotic Resistance Genes and Virulence Genes in Multiple Antibiotic-Resistant Escherichia coli Strains from Leafy Vegetables

Abstract

Managing bacterial infections becomes particularly challenging when antibiotic-resistant organisms are involved, especially multiple antibiotic-resistant (MAR) strains. Leafy vegetables consumed raw can harbor MAR pathogens, serving as transmission vehicles to consumers. This study examined the co-presence of antibiotic resistance and virulence genes in MAR strains among 18 Escherichia coli isolates from retailed leafy vegetables. Eight strains with MAR index > 0.6 were selected and screened for resistance genes (parC, aad2, TEM, qnrA, aac(3)-IV, shv, ctx-m, ant(2″)-I) and virulence genes (fimH, usp, stx1). Casein, gelatinase, haemolysis, and proteinase activities were also assessed. The TEM gene was detected in all isolates, while shv, aad2, ctx-m, ant(2″)-I, qnrA, and aac(3)-IV were found in varying frequencies. Among virulence genes, usp was present in seven isolates, while stx1 and fimH were detected in five. Two isolates carried all three virulence genes. Eight distinct co-presence patterns of resistance and virulence genes were identified. These findings highlight potential challenges in managing infections caused by such isolates, emphasizing the need for robust antibiotic stewardship and careful handling of leafy vegetables, particularly those consumed raw.