Resistance to Erythromycin in Group A Streptococci

Abstract

Abstract Background. The use of erythromycin in Finland nearly tripled from 1979 to 1989. In 1988, we observed an unusually high frequency of resistance to erythromycin in group A streptococci in one geographic region. Because routine testing does not detect the sensitivity of these organisms to antibiotics, we initiated a national study to evaluate the extent of this resistance. Methods. We studied 272 isolates of group A streptococci obtained from blood cultures from 1988 through 1990. In 1990 we collected from six regional laboratories 3087 consecutive isolates from throat swabs and 1349 isolates from pus samples. Resistance was indicated by growth on blood agar containing 2 μg of erythromycin per milliliter after incubation in 5 percent carbon dioxide. We also evaluated the clinical importance of erythromycin resistance in a retrospective study of consecutive patients with pharyngitis. Results. The frequency of resistance to erythromycin in group A streptococci from blood cultures increased from 4 per...