Increased resistance of streptococci to macrolides in Germany

The aim of a multicenter study in Germany was to assess the resistance of Streptococcus pneumoniae and Streptococcus pyogenes to macrolides in children under 16 years of age from 2000 to 2001.

In 13 microbiology laboratories, 307 S.pyogenes strains isolated from ambulatory patients with tonsillopharyngitis and 333 S.pneumoniae strains from individuals suffering from respiratory infections.

The minimum inhibitory concentrations (MICs) for the following antibiotics were determined using the broth microdilution method: benzylpenicillin, amoxicillin, cefotaxime, erythromycin, clindamycin, levofloxacin and telithromycin.

No S. pyogenes strain resistant to benzylpenicillin and levofloxacin was detected. At the same time, the frequency of resistance to erythromycin was 13.7%. Telithromycin had relatively high activity against S. pyogenes (MPC90 = 0.25 mg / L; IPC range 0.016-16 mg / L), and only 3 strains were resistant to telithromycin (IPC plus 4 mg / l).

Among the strains resistant to erythromycin, 40.5% of the strains had an active ejection mechanism (efflux) coded by the mef (A) gene, 38.1% had a ribosomal methylation coded by the erm (A) genes and 9.5% erm (B).

Among the S. pneumoniae strains, no strain with a high level of penicillin resistance and resistant to levofloxacin was detected. At the same time, resistance to erythromycin was 17.4% and 7.5% of the strains had an intermediate level of penicillin resistance. For pneumococci, telithromycin also had high activity (MPC90 less than 0.016 mg / l; IPC range 0.016-0.5 mg / l).

The results of the study led to the conclusion that the resistance level is at a fairly low level, but, nevertheless, there is a clear tendency to increase resistance to macrolides.