Objectives. To investigate the antimicrobial susceptibility profiles of clinical isolates of Streptococcus pneumoniae and Streptococcus pyogenes, isolated from children within Great Britain and Ireland (Northern Ireland and Eire), with particular reference to the new oral ketolide telithromycin. To determine the distribution of macrolide resistance genes within the erythromycin resistant population.

Methods. MICs were determined using NCCLS microbroth dilution methodology and macrolide resistance mechanisms were investigated using PCR.

Results. Penicillin susceptibility was found to be 92.6% in S. pneumoniae isolates (n=831; 3.7% intermediate, MIC 0.12–1 mg/l, 3.7% resistant, MIC >2.0 mg/l) and 100% in S. pyogenes isolates (n=1333). 8.8% of S. pneumoniae and 2.5% of S. pyogenes isolates demonstrated erythromycin-A resistance (EryA^R). One hundred percent of S. pneumoniae and 99.8% of S. pyogenes isolates were susceptible to telithromycin (MIC≤1.0 mg/l). Of the 73 EryA^RS. pneumoniae isolates tested, 55 (75.3%) were mef (A) positive, 17 (23.3%) erm (B) positive and one isolate (1.4%) was positive for both mechanisms. Of the 34 isolates of EryA^RS. pyogenes tested, 23 (67.6%) were erm (A) subclass erm (TR) positive, 4 (11.8%) erm (B) and 7 (20.6%) mef (A) positive.

Conclusions. This paper presents baseline data on penicillin and macrolide resistance in S. pneumoniae and S. pyogenes isolates in the paediatric population of Great Britain and Ireland. Telithromycin, recently approved for the treatment of community acquired respiratory tract infections (CARTI) in patients over 12 years of age throughout the European community, demonstrated high in vitro activity against these pathogens, including EryA^R strains.