Molecular Epidemiology and Antibacterial Susceptibility of Streptococci Isolated from Healthy Children Attending Day Care Units

Objective: The aims of the study were to investigate antibacterial susceptibility and resistance mechanisms of streptococci isolated from healthy chil- dren attending day care units and to evaluate clonal relatedness of the strains. Material and Methods: Antimicrobial susceptibilities of streptococci isolated from 212 children attending 3 different day care units were evaluated using the agar dilution method. Polymerase chain reaction and sequencing were used to investigate resistance mechanisms. Clonal relatedness was evaluated using pulsed field gel electrophoresis. Results: Of 212 children, 11 (5.2%) carried Streptococcus pneumoniae, 17 (8.0%) S. pyogenes, and 42 (19.8%) erythromycin resistant viridans group streptococci. All S. pyogenes were susceptible to penicillin G and macrolides. Ten of 11 clonally unique S. pneumoniae were resistant to penicillin G. Three of 11 S. pneumoniae were macrolide resistant and carried erm(B). Among clonally unique 42 erythromycin resistant viridans group streptococci, 2 (4.8%) had erm(B), 33 (78.6%) had mef(A) and 7 (16.6%) had both erm(B) and mef(A) genes. All S. pyogenes from the first centre and three strains from the second centre were pulse-type A. Conclusion: Among healthy children, colonization with penicillin resistant pneumococci and erythromycin resistant viridans group streptococci is quite high. Clonal spread of S. pyogenes is important for day care units.