Methicillin-resistant S. aureus colonization in Mexican children attending day care centres

Purpose: To determine MRSA carriage rates and genetic relationships of S. aureus strains in children attending day care centres in 14 cities from three geographic regions in Mexico. Materials and methods: Cross-Sectional Study performed in apparently healthy children aged from 6 mo to 6 yr attending day care centres (DCCs). From September 2002 To January 2003, 2345 nasopharyngeal specimens from a similar number of children were collected. Nasopharyngeal samples for bacterial isolation were obtained by standard methods. Antimicrobial susceptibility was determined and genetic relatedness of all MRSA isolates was determined by pulsed field gel electrophoresis (PFGE). Results: S. aureus was identified in 237 children (10.1%), twenty-two children had MSRA for an overall prevalence of MRSA carriage of 0.93%. Children attending DCCs from cities located in the north and south of Mexico showed higher prevalence than children from DCCs in the central region; 1.75%, and 1.71 vs. 0.08%, respectively (P<0.05). PFGE demonstrated six different restriction profiles of MRSA with a predominant pattern. Conclusions: We documented the presence of MRSA strain colonizing children attending DCCs in Mexico, mainly in the south and north regions of the country. Clone A and B which are closely related represented 45% of the total of MRSA isolates. We found both, SCCmec type II and type IV strains in the three regions.