Susceptibility of Streptococcus pyogenes to two macrolides in northern Israel.

In the present study, the minimal inhibitory concentration (MIC) of azithromycin and roxithromycin for 200 Streptococcus pyogenes isolates from outpatients with tonsillopharyngitis were determined using Etest. All but one (99.5%) of the isolates were sensitive to both antibiotics; the MIC of the resistant isolate being 12 mg/l to azithromycin and 32 mg/l to roxithromycin. In this region, macrolides remain the drug of choice for the treatment of patients with S. pyogenes tonsillitis who present allergy to penicillin. The routine testing of susceptibility of S. pyogenes to macrolides in northern Israel is not justified.