Streptococcus peumoniae in an Egyptian urban community: incidence of erythromycin-resistance determinants and antibiotic susceptibility profile

Objectives: To determine the incidence of resistance of Streptococcus (Strep). pneumoniae isolated in our locality to erythromycin, to screen for the two resistance determinants erm (B) and mef (A) genes, and to identify the susceptibility profile to commonly used antibiotics. Methods: Samples were collected from patients attending the Outpatient Department of Zagazig University Hospital, Zagazig, Egypt, between February 2006 and March 2007. Strep. pneumoniae was identified by conventional procedures. Susceptibilities to erythromycin and 15 antibiotics were identified by disc diffusion method, as outlined by CLSI. E-test was used for MIC determination of erythromycin. erm (B) and mef (A) genes were detected by PCR. Results: Eighty-one Strep. pneumoniae strains were identified. Fifty-one of them (63\%) were erythromycin-resistant, and mef (A) gene was the predominant resistance determinant. Vancomycin, imipenem and gatifloxacin had the best activity against the isolates, whereas tetracycline had the least. Forty-two (51.85\%) out of the 81 Strep. pneumoniae strains were multidrug-resistant. Conclusions: High incidence of resistance to erythromycin and multiple anti-microbials existed. mef (A) was the principal erythromycin-resistance gene.