Isolation rate, T-serotyping and susceptibility to antibiotics of Group A Streptococcus from pediatric infections in Athens

Objective The epidemiology of Group A Streptococcus (GAS) in Greece is not known. We have therefore conducted this prospective study to investigate the isolation rate of GAS From pediatric specimens, determine T-serotype frequency and examine the susceptibility of GAS to penicillin, erythromycin and clindamycin. Methods Over a 3-year study-period (1993-95) 11 597 clinical specimens obtained from sick children were inoculated on appropriate culture media. The isolation and identification of GAS strains were assessed by conventional methods. T-typing was performed by slide agglutination. Serum opacity factor (OF) was detected by microwell method. The susceptibility of the strains was tested by the Kirby Bauer method. Results GAS were isolated from 1125 out of 11 597 (9.7%) clinical specimens, mostly from throat samples (15.6%). T-serotyping was performed in 652 GAS strains. A significant difference of the incidence of T-serotypes was observed within the 3 years studied (chi (2) = 70.3, DF = 18, P < 0.001). The most dominant isolates were T-1 (25%), T-3 (20%) and T-12 (16%) during 1993, 1994 and 1995, respectively Non-typeable (NT) strains were 4%. OF and hyaluronic acid were produced front 49.8% and 3% of the strains, respectively All isolated strains were susceptible to penicillin and clindamycin. Resistance to erythromycin was 5.0-8.7% over the 3-year study period. Conclusions There was a wide distribution of GAS T-serotypes in Athens and a significant change in their annual predominance. All strains were susceptible to penicillin and clindamycin, but a low level of erythromycin resistance was observed.