The risk of pig and chicken farming for carriage and transmission of containing extended-spectrum beta-lactamase (ESBL) and mobile colistin resistance () genes in Thailand.

South-East Asian countries report a high prevalence of extended-spectrum cephalosporin- (ESC-) and colistin-resistant (Col-R-). However, there are still few studies describing the molecular mechanisms and transmission dynamics of ESC-R- and, especially, Col-R-. This study aimed to evaluate the prevalence and transmission dynamics of containing extended spectrum beta-lactamases (ESBL) and mobile colistin resistance () genes using a 'One Health' design in Thailand. The ESC-R- and Col-R- isolates of human stool samples (69 pig farmers, 155 chicken farmers, and 61 non-farmers), rectal swabs from animals (269 pigs and 318 chickens), and the intestinal contents of 196 rodents were investigated. Resistance mechanisms and transmission dynamics of isolates (=638) were studied using short and long read sequencing. We found higher rates of ESBL- isolates among pig farmers (=36; 52.2%) than among chicken farmers (=58; 37.4 %; <0.05) and the control group (=61; 31.1 %; <0.05). with co-occurring ESBL and genes were found in 17 (6.0 %), 50 (18.6 %) and 15 (4.7 %) samples from humans, pigs and chickens, respectively. We also identified 39 (13.7 %) human samples with non-identical containing ESBL and . We found higher rates of ESBL- in particular CTX-M-55 isolates among pig farmers than among non-pig farmers (<0.01). 'Clonal' animal-human transmission of ESBL- and with genes was identified but rare as we overall found a heterogenous population structure of . The Col-R- from human and animal samples often carried -1.1 on conjugative IncX4 plasmids. The latter has been identified in of many different clonal backgrounds.