High prevalence of carriage of mcr-1-positive enteric bacteria among healthy children from rural communities in the Chaco region, Bolivia, September to October 2016


The  gene is a transferable colistin resistance determinant that was first described among enterobacterial strains isolated from animals and humans in China. The gene encodes a phosphoethanolamine transferase that modifies the colistin target by addition of phosphoethanolamine to the 1’ or 4’ phosphate group of lipid A, which reduces its affinity to colistin [1,2]. Discovery of  was considered highly alarming, given the role that colistin has recently regained as a last-resort antibiotic for treatment of infections caused by multi-resistant Gram-negative pathogens such as carbapenem-resistant Enterobacterales and  [1,3].

Subsequent to its discovery, several studies have revealed a global distribution of , with an overall higher prevalence among  and , and occasional occurrence in other enterobacterial species. Most -positive strains were of animal origin, and farm animals were identified as the principal reservoir of  genes [1,4]. Investigation of archival strains dated the presence of  back to at least the 1980s [5]. As with other resistance genes, minor allelic variants of  have been detected [6]. More recently, additional transferable  genes ( and ) have been reported, for which the global epidemiology remains to be clarified [713].

In South America,  genes have been reported from several countries in isolates from humans, animals and food [1427]. Recently, the Pan American Health Organisation (PAHO) section of the World Health Organization (WHO) recommended to implement and strengthen surveillance and epidemiological investigation of plasmid-mediated transferable colistin resistance in its Member States [14]. In Bolivia,  has thus far been reported in a  that was isolated from a ready-to-eat food sample [21], as well as in a few clinical isolates of  referred from various departments to the National Institute of Health Laboratories (INLASA) (data not shown).

During the last two decades we carried out several surveillance studies in the Bolivian Chaco region, documenting a high prevalence of resistance to old and more recent antibiotics in commensal and pathogenic bacteria from humans [21,2832].

In 2016, a new surveillance study was carried out in a population of healthy school children from several rural communities in this region to investigate the prevalence of intestinal parasites and the carriage of antibiotic-resistant bacteria. Here we report about an unexpected and high rate of faecal carriage of -positive Enterobacterales in this population.

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By |2018-11-10T18:28:42+00:00November 10th, 2018|

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