Characterization of Enterobacterales Resistant to Extended-Spectrum Cephalosporins Isolated from Meat in Tunisia

Abstract

Food-producing animals are potential reservoirs of resistance to antibiotics classified as critically important for human health, such as extended-spectrum cephalosporins (ESC) and carbapenems (CP). Even though human-to-human contacts are the primary vector of antimicrobial resistance (AMR) dissemination in the community, food consumption and preparation play a nonnegligible role in the global burden. In order to document the levels of meat contamination in Tunisia, 71 samples of meat products (chicken, n = 25; sheep, n = 30; bovine, n = 7; goat, n = 6; camel, n = 3) collected in 2024 in the Sousse region were studied using selective media, antibiograms, as well as short- and long-read sequencing. No CP-resistant isolate was identified, but 46 (64.8%) of the samples carried ESC-R Enterobacterales, with chicken meat being the most contaminated meat (80%). The collected isolates were identified as Escherichia coli (68.0%), Klebsiella pneumoniae (26.0%), and Enterobacter hormaechei (6.0%), most of which carried bla_CTX-M-type genes. Despite a high genetic diversity, clonal spread was suspected in several cases, notably due to clones (ST540, ST155, ST117) presenting a zoonotic and/or One Health importance. Plasmids also played a role in the spread of resistance. We observed the decline of the IncI1/ST3 but the presence of the IncF/F-:A-:B53 and IncY, which are both emerging as important carriers of the bla_CTX-M-15 gene worldwide. This study revealed the need for surveillance and the effective implementation of the national action plan in the veterinary sector to decrease the AMR burden in the food-producing sector.