Abstract
Erythromycin resistance among
Streptococcus pyogenes
strains has been reported in Italy at high rates during the last few years. A total of 152 erythromycin-resistant isolates of this species from
southern Italian regions were characterized for the macrolide-resistance phenotype and screened by PCR for the corresponding genetic determinant. A close correlation was found between these phenotypic/genotypic
data concerning macrolide resistance and results of
Sma
I macrorestriction fragment patterns (PFGE) analysis. In fact, the vast majority of the isolates assigned to individual PFGE classes mostly
belonged to a single phenotype of macrolide resistance. All untypeable isolates belonged to the M phenotype. Twenty-two distinct PFGE types were recognized, of which 11 were recorded in only one isolate
(one-strain type); about 50% of typeable isolates fell into five type clusters and 70% in seven. The increased erythromycin resistance among Italian isolates of
S. pyogenes
does not appear to be
due to the spread of a single clone, but results indicate that the majority of group A streptococci examined are probably spread from a limited number of clones.