Inducible clindamycin resistance among methicillin-sensitive Staphylococcus aureus infections in pediatric patients.

BACKGROUND Staphylococcus aureus infections are a major cause of morbidity and mortality worldwide. Clindamycin is widely used in the treatment of staphylococcal infections; however, it is our impression that in the last few years, inducible clindamycin resistance (ICR) has become more prevalent. OBJECTIVE To assess the prevalence of ICR in methicillin-sensitive Staphylococcus aureus (MSSA) infections among pediatric patients in Israel. METHODS We reviewed the files of children diagnosed with MSSA infections during the period January 2006 to June 2007 forfull antibiogram (includingthe D-test for ICR), phage typing and randomly amplified polymorphic DNA. RESULTS Altogether, 240 MSSA isolates were recovered, mainly from wounds and abscesses. ICR was detected in 62 of 68 erythromycin-resistant/clindamycin-sensitive strains (91%); the ICR rate for the total number of isolates was 26% (62/240). Phage type analysis demonstrated that 38 of 61 ICR isolates (62%) were sensitive to group 2, compared to 42 of 172 isolates (24%) that did not express ICR (P < 0.01). On randomly amplified polymorphic DNA, phage type 2 isolates expressing ICR belonged to the same clone, which was different from ICR isolates sensitive to other phages and from isolates not expressing ICR. CONCLUSIONS Inducible clindamycin resistance is common among methicillin-sensitive Staphylococcus aureus in Israeli children. The D-test should be performed routinely in all MSSA isolates.