[Methicillin-resistant Staphylococcus aureus. Detection of carriers among hospitalized children and healthy children from the community].

A descriptive punctual study was conducted to search for nasal carriers of Staphylococcus aureus strains resistant to methycilin (SARM) among sound children attended in nurseries and hospitalized children exposed to one or more risk factors predisposing to the colonization by this type of strains from October, 2000, to February, 2001, in Marianao municipality. For the primary isolation of the SARM strains, it was used the oxacillin-manitol-salt-agar (OMSA) and the sensitivity to antimicrobial drugs was determined in all strains identified as S. aureus by using the Kirby-Bauer method. In order to identify the resistance to oxacillin in the strains recovered from OMSA, the oxacillin salt-agar screening-plate method and the determination of inhibitory minimum concentration (IMC) in agar and broth were applied. The presence of the mecA gene was nvestigated by polymerase chain reaction in those strains with an IMC > or = 4 mg/mL of oxacillin. Of the sound children. 0.35 % and of the hospitalized, 2 %, were nasal carriers of SARM strains. The strains isolated in both study groups showed high indexes of resistance to penicillin, tetracycline and erythromycin by the Kirby-Bauer method. The mecA gene was identified in a SARM strain isolated from a hospitalized nasal carrier and it was defined that its behaviour agreed with the one described for a strain homoresistant to oxacillin.