Evolution of Nasal Carriage of Methicillin-Resistant Coagulase-Negative Staphylococci in a Remote Population

Abstract

ABSTRACTNasal carriage of methicillin-resistant coagulase-negative staphylococci (MR-CoNS) is highly prevalent in community subjects, but its dynamic has been little investigated. Nasal swabbing was performed in 2006 and 2008 in 154 Amerindians living isolated in French Guiana. MR-CoNS strains were identified and characterized by non-β-lactam susceptibility testing and staphylococcal cassette chromosomemecelement (SCCmec) typing, characterizing the associations ofccrandmecgene complex allotypes, and for MRStaphylococcus epidermidis(MRSE), multilocus variable number of tandem repeats analysis (MLVA) was used. The impact of sociodemographic and medical characteristics on the persistence of MR-CoNS carriage was assessed by bivariate analysis. Prevalence of MR-CoNS carriage was 50.6% in 2006 and 46.8% in 2008. The 274 MR-CoNS isolates, includingS. epidermidis(n= 89, 62 MLVA patterns),Staphylococcus haemolyticus(n= 78), andStaphylococcus hominis(n= 72), exhibited 41 distinctccrandmecgene complex associations. Persistent carriage (in 2006 and 2008), intermittent carriage (either in 2006 or 2008), and noncarriage were documented in 25.3, 47.4, and 27.3% of the participants, respectively. Persistent carriage of a given MRSE isolate was rarely observed (n= 8 isolates). Furthermore, no epidemiological factor, including antibiotic exposure, was associated with persistent carriage. The high diversity of MRSE clones and theirccrandmecgene complex associations contrasted with the high carriage rates in this isolated community, which might reflect the occurrence of SCCmecrearrangement and the generation of new MR-CoNS strains.