Unexplained High Prevalence of ESBL-Escherichia coli Among Cattle and Pigs in Peru

<b>Background/Objectives</b>: Extended-Spectrum Beta-Lactamase-producing <i>Escherichia coli</i> (ESBL-<i>E. coli</i>) are widely circulating in livestock of low- and middle-income countries. However, the drivers of their circulation remain largely unknown. Small-scale farms in Peru exhibit an unusually high prevalence of fecal carriage of ESBL-<i>E. coli</i> in their livestock. The objective of this study was to compare the prevalence of ESBL-<i>E. coli</i> fecal carriage in dairy cows, pigs, and poultry in the Lima and Ica regions of Peru and to identify the drivers associated with the observed prevalence at the farm level. <b>Methods</b>: We compared the prevalence of fecal carriage of ESBL-<i>E. coli</i> isolated from dairy cattle (N = 244 animals; 25 farms), pigs (N = 261; 25), and laying hens (N = 255; 10). We also administrated questionnaires to 59 farmers regarding their socioeconomic status, husbandry practices, animal diseases, and antibiotic use. <b>Results</b>: All but one of the 60 farms sampled had at least one animal carrying ESBL-<i>E. coli</i>. A statistically higher prevalence of ESBL-<i>E. coli</i> was estimated in dairy cows (75%) and pigs (61%) from Lima compared to laying hens from Ica (34%). Our statistical analyses (Poisson generalized linear models) using two variable selection approaches revealed that the prevalence of ESBL-<i>E. coli</i> was lower in farms raising laying hens, when farmers oversaw both animal husbandry and healthcare, and in farms with a lower number of gastrointestinal outbreaks in the last semester. Socio-economic features of farmers and self-reporting antibiotic use varied across farms (i.e., highest antibiotic use over the last semester was reported among pig farmers (96%), followed by laying hen (70%) and dairy cattle farmers (50%)), but these factors were not associated with the prevalence of ESBL-<i>E. coli</i>. <b>Conclusions</b>: Despite a relatively low number of farms sampled, our findings suggest that the widespread circulation of ESBL-<i>E. coli</i> among livestock in Peru could be mainly associated with unknown species-specific drivers, independently of the socioeconomic status of farmers and antibiotic use. Therefore, our study calls for future research to identify the specific drivers promoting the high prevalence of ESBL-<i>E. coli</i> among cattle and pigs in Peru.