High prevalence of carriage of -positive enteric bacteria among healthy children from rural communities in the Chaco region, Bolivia, September to October 2016.

BackgroundThe gene is a transferable resistance determinant against colistin, a last-resort antimicrobial for infections caused by multi-resistant Gram-negatives.AimTo study carriage of antibiotic-resistant bacteria in healthy school children as part of a helminth control and antimicrobial resistance survey in the Bolivian Chaco region.MethodsFrom September to October 2016 we collected faecal samples from healthy children in eight rural villages. Samples were screened for - and genes. Antimicrobial susceptibility testing was performed, and a subset of 18 isolates representative of individuals from different villages was analysed by whole genome sequencing (WGS).ResultsWe included 337 children (mean age: 9.2 years, range: 7-11; 53% females). The proportion of carriers was high (38.3%) and present in all villages; only four children had previous antibiotic exposure. One or more -positive isolates were recovered from 129 positive samples, yielding a total of 173 isolates (171 , 1 , 1 ). No was detected. Co-resistance to other antimicrobials varied in -positive . All 171 isolates were susceptible to carbapenems and tigecycline; 41 (24.0%) were extended-spectrum β-lactamase producers and most of them (37/41) carried -type genes. WGS revealed heterogeneity of clonal lineages and -genetic supports.ConclusionThis high prevalence of -like carriage, in absence of professional exposure, is unexpected. Its extent at the national level should be investigated with priority. Possible causes should be studied; they may include unrestricted use of colistin in veterinary medicine and animal breeding, and importation of -positive bacteria via food and animals.