Survey of emm gene sequences from pharyngeal Streptococcus pyogenes isolates collected in Spain and their relationship with erythromycin susceptibility

Abstract

We conducted a nationwide survey of the variable 5' emm (M protein gene) sequences from 614 pharyngeal Streptococcus pyogenes isolates susceptible (299 isolates) and resistant (315 isolates) to erythromycin that were isolated in Spain from 1996 to 1999. Almost 98% of these isolates had emm sequences in agreement with previously recorded M antigen association. We only identified a new 5' emm sequence in 17 isolates. Nine different emm types accounted for 85% of the S. pyogenes isolates susceptible to erythromycin. By contrast, only 3 emm types accounted for 70% of the erythromycin-resistant isolates. Further characterization of these isolates by ribotyping and pulsed-field gel electrophoresis indicated that high frequency of erythromycin resistance in Spain is due to few clones.

FIG. 1.

Representative ribotypes (A) and PFGE types (B) of erythromycin-resistant S. pyogenes M types 4, st1815, and 75 isolated between 1996 to 1997 and 1998 to 1999 in Spain. (A) Southern blot of genomic S. pyogenes DNA digested with SacI and probed with a GAS 16S rRNA gene probe as described in Materials in Methods. (B) PFGE analysis of genomic DNA restricted with SfiI. Letters on the lanes refer to types, and numbers below each lane refer to the number of isolates of each type. Molecular size markers (in kilobases) are indicated on the left.