Characterization of Enterobacterales resistant to extended-spectrum cephalosporins isolated from meat in Tunisia

Food-producing animals are potential reservoirs of resistances 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 plays a non-negligible 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 E. coli (68.0%), K. pneumoniae (26.0%) and Enterobacter hormaechei (6.0%), most of which carried blaCTX-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 blaCTX-M-15 gene worldwide. This study revealed the need of surveillance and the effective implementation of the national action plan in the veterinary sector to decrease the AMR burden in the food-producing sector.