Serotype 19F multiresistant pneumococcal clone harboring two erythromycin resistance determinants [erm(B) and mef(A)] in South Africa

One hundred eighteen erythromycin-resistant Streptococcus pneumoniae (ERSP) strains (MICs of ≥0.5 μg/ml) from five laboratories serving the private sector in South Africa were analyzed for the genes encoding resistance to macrolides. Sixty-seven ERSP strains (56.8%) contained the erm(B) gene, and 15 isolates (12.7%) contained the mef(A) gene. Thirty-six isolates (30.5%) harbored both the erm(B) and mef(A) genes and were highly resistant to erythromycin and clindamycin. DNA fingerprinting by BOX-PCR and pulsed-field gel electrophoresis identified 83% of these strains as belonging to a single multiresistant serotype 19F clone.