The emergence of erythromycin resistance in Streptococcus pyogenes in Fremantle, Western Australia.

Erythromycin resistance in Streptococcus pyogenes is unusual except in Japan. Since January 1, 1985, a dramatic increase has occurred in the prevalence of erythromycin-resistant Strept. pyogenes infections in the outpatients who have presented to Fremantle Hospital, Western Australia. In 1985, 1% of isolates of Strept. pyogenes was erythromycin-resistant. This had risen to 9.1% of isolates in 1986 and to 17.6% of isolates in 1987. Several M- and T-types of Strept. pyogenes were involved. Treatment failure now can be expected when erythromycin is prescribed for the treatment of common infections in outpatients at this hospital. Laboratories that use disc methods of antimicrobial susceptibility testing may not detect erythromycin resistance in these organisms.