Utilisation of macrolides and the development of Streptococcus pyogenes resistance to erythromycin.

Objectives: The aim of the study was to evaluate the relationship between the development of the resistance of Streptococcus pyogenes strains to erythromycin and the utilisation of macrolides in the Olomouc region, Czech Republic.

Method: During the period 1997-2001, data for utilisation of macrolides was obtained from the database of the regional General Health Insurance Company and expressed indefined daily doses per 1,000 patients per day. S. pyogenes strains were isolated from community patients suffering from acute bacterial tonsillitis. Their susceptibility to antibiotics was assessed by the disk diffusion method.

Results: Utilisation of macrolides increased by 13% in the period 1997-2001; their utilisation represented 11.40% of total antibiotic prescription in 1997 and 15.48% in 2001. Occurrence of erythromycin-resistant S. pyogenes strains increased significantly from 14% in 1997 to 32% in the year 2001 (P < 0.01). In 2000, macrolides consumption decreased non-significantly, but with no concomitant decrease in erythromycin-resistant S. pyogenes strains occurrence. Absolute susceptibility of S. pyogenes, the most important bacterial pathogen in community-acquired bacterial tonsillitis, to penicillin contrasts with increasing macrolide resistance.

Conclusions: The study documents the influence of increased utilisation of macrolides on bacterial resistance. Penicillin should be a first-choice antibiotic in acute bacterial tornsillitis; macrolides should only be reserved for patients allergic to penicillins.