Macrolide resistance in group A beta haemolytic Streptococcus isolated from outpatient children in Latvia.

Group A streptococci (GAS) are responsible for up to 30% of cases of pharyngitis in children, and such children do not benefit from treatment with antibiotics. During the last decade, increased resistance to macrolides has emerged as a critical issue in the treatment of GAS pharyngitis. The objective of this study was to determine the antimicrobial resistance of group A beta haemolytic Streptococcus isolated from outpatient children. From 2002 to 2006, 96 GAS strains were obtained from the pharynx of outpatients having symptoms of acute pharyngitis. Antibiotic resistance was determined by disc susceptibility tests according to CLSI standards. The presence of ermA, ermB and mefA was established by the amplification of streptococcal DNA with specific primers. Antimicrobial susceptibility tests revealed that all the strains tested were sensitive to vancomycin, linezolid, penicillin and ceftriaxone. Simultaneously, high levels of resistance to macrolides were evident; 78% of the isolates were resistant to clindamycin and erythromycin. No significant change in the yearly or seasonal incidence of resistance was observed. We describe high antimicrobial resistance of GAS to macrolides in outpatient children (78%), which can be explained by the frequent use of macrolides in the treatment of such individuals. Therefore, macrolides should not be the first drug of choice.

Susceptibilities to telithromycin and six other agents and prevalence of macrolide resistance due to L4 ribosomal protein mutation among 992 Pneumococci from 10 central and Eastern European countries.

The macrolide and levofloxacin susceptibilities of 992 isolates of Streptococcus pneumoniae from clinical specimens collected in 1999 and 2000 were determined in 10 centers in Central and Eastern European countries. The prevalences of penicillin G-intermediate (MICs, 0.125 to 1 microg/ml) and penicillin-resistant (MICs, < or =2 microg/ml) Streptococcus pneumoniae isolates were 14.3 and 16.6%, respectively. The MICs at which 50% of isolates are inhibited (MIC(50)s) and the MIC(90)s of telithromycin were 0.016 and 0.06 microg/ml, respectively; those of erythromycin were 0.06 and >64 microg/ml, respectively; those of azithromycin were 0.125 and >64 microg/ml, respectively; those of clarithromycin were 0.03 and >64 microg/ml, respectively; and those of clindamycin were 0.06 and >64 microg/ml, respectively. Erythromycin resistance was found in 180 S. pneumoniae isolates (18.1%); the highest prevalence of erythromycin-resistant S. pneumoniae was observed in Hungary (35.5%). Among erythromycin-resistant S. pneumoniae isolates, strains harboring erm(B) genes (125 strains [69.4%]) were found to be predominant over strains with mef(E) genes (25 strains [13.4%]), L4 protein mutations (28 strains [15.6%]), and erm(A) genes (2 strains [1.1%]). Similar pulsed-field gel electrophoresis patterns suggested that some strains containing L4 mutations from the Slovak Republic, Bulgaria, and Latvia were clonally related. Of nine strains highly resistant to levofloxacin (MICs, >8 microg/ml) six were isolated from Zagreb, Croatia. Telithromycin at < or =0.5 microg/ml was active against 99.8% of S. pneumoniae isolates tested and may be useful for the treatment of respiratory tract infections caused by macrolide-resistant S. pneumoniae isolates.

Susceptibility to telithromycin in 1,011 Streptococcus pyogenes isolates from 10 central and Eastern European countries.

Among 1,011 recently isolated Streptococcus pyogenes isolates from 10 Central and Eastern European centers, the MICs at which 50% of isolates are inhibited (MIC(50)s) and the MIC(90)s were as follows: for telithromycin, 0.03 and 0.06 microg/ml, respectively; for erythromycin, azithromycin, and clarithromycin, 0.06 to 0.125 and 1 to 8 microg/ml, respectively; and for clindamycin, 0.125 and 0.125 microg/ml, respectively. Erythromycin resistance occurred in 12.3% of strains. Erm(A) [subclass erm(TR)] was most commonly encountered (60.5%), followed by mef(A) (23.4%) and erm(B) (14.5%). At <0.5 microg/ml, telithromycin was active against 98.5% of the strains tested.