Relevant increase of CTX-M-producing Escherichia coli carriage in school-aged children from rural areas of the Bolivian Chaco in a three-year period

Objectives: The aim of this study was to perform two cross-sectional surveys on the fecal carriage of CTX-M-producing Enterobacterales in school-aged children from rural areas of the Bolivian Chaco (2016 vs 2019).Methods: A total of 757 fecal samples were collected from school-aged children living in nine indigenous communities (n=337, 2016; n=420, 2019). After a first passage onto MacConkey agar (MCA), samples were plated onto MCA plus cefotaxime 2 mu g/mL (MCA-CTX), and a loopful of the bacterial growth was used as a template for the detection of group 1, 2, 8/25, and 9 bla(CTX-M) variants by multiplex reverse transcriptase polymerase chain reaction. Positive samples were tested again for detecting, identifying, and characterizing CTX-M-positive isolates.Results: Growth onto MCA-CTX was obtained with 208 samples (27.5%; 62/337, 2016; 146/420, 2019), of which 201 (96.6%) were positive for bla(CTX-M) genes. Overall, a relevant increase of fecal carriage of CTX-M-producing Enterobacterales was observed in the study period: 17,5% (59/337) in 2016 compared with 33,8% (142/420) in 2019, p<0.01. Nonetheless, the relative group distribution of CTX-M groups remained stable, with group 1 being the prevalent, followed by group 9 and group 8/25. Group 2 was not detected.Conclusions: The present study demonstrated an alarming spread of CTX-M enzymes in rural areas of the Bolivian Chaco, where antibiotics consumption is limited. Further studies are encouraged to better understand the dissemination dynamics of such relevant resistance determinants. (C) 2022 The Authors. Published by Elsevier Ltd on behalf of International Society for Infectious Diseases.