Prevalence and determinants of carrying third-generation cephalosporin-resistant enterobacteria in Rattus sp. in Reunion and Mayotte

Abstract

Enterobacteriaceae resistant to third generation cephalosporins (ER3GC) constitute a major health issue for humans and animals in the Indian Ocean. Rats are synanthropic reservoirs. We have used rats as environmental bioindicators of the occurrence of ER3GC. The main objective of this exploratory study was to generate hypotheses on environmental contamination by ER3GC in the two French territories of the Indian Ocean. This objective was addressed by i) estimating the prevalence of ER3GC and of extended-spectrum β-lactamase producing enterobacteria (ESBL-E) in rats from the two territories in 2013-2014, and ii) identifying the determinants of this carriage in rats (life history traits and land use). In 2013-2014, rats were sampled according to an altitudinal gradient in Reunion and Mayotte on several sites with low anthropization. From a convenience sample of 198 and 138 rats in Reunion and Mayotte, respectively, the prevalence of ER3GC was 5.1% and 8.7%, and the prevalence of ESBL-E was 0.5% and 0.8%. The mass, tail length, and proportion of agricultural land in the home range of the rat were determinants of ER3GC carriage in Reunion. In Mayotte, the determinants of this carriage were a low mass and the capture site of the rat with a cluster of positive cases at a specific location. Finally, the results obtained seem to indicate a low environmental contamination by ER3GC in Reunion and Mayotte in 2013-2014. In Reunion, the hypothesis of environmental contamination by slurry spraying was raised, requiring further investigations.