Streptococcal toxic shock syndrome by an iMLS resistant M type 77 Streptococcus pyogenes in the Netherlands.

An increasing number of group A streptococci (GAS) with constitutive or inducible resistance to macrolide-lincosamide-streptogramin B antibiotics (cMLS or iMLS phenotype) is observed in Europe, but MLS resistant GAS associated with streptococcal toxic shock syndrome (STSS) has not been reported. We describe a patient admitted with STSS caused by an iMLS resistant T28 M77 Streptococcus pyogenes carrying the ermA [subclass TR] gene. A 2-y retrospective analysis among 701 nationwide collected GAS strains revealed an incidence of 3.1% of this M type 77 GAS. Analysis of 17 available M77 strains (12 T28 and 5 T13) indicated that 2 (12%) were MLS resistant due to the ermA [TR] gene. Both MLS resistant strains were cultured from blood and belonged to T28 serotype. Multilocus sequence typing (MLST) showed that all M77 isolates belonged to sequence type 63. We conclude that 17 M77 GAS collected in the Netherlands in a 2-y period were associated with invasive disease and belonged to the same clonal complex. Since only 12% carried the ermA [TR] resistance gene, it is very likely that the gene has been acquired by horizontal transmission rather than from spread of a resistant circulating clone.