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Unusual occurrence of M type 77, antibiotic-resistant group A streptococci in southern Sweden

A Jasir1, A Tanna, A Efstratiou

  • 1Department of Infectious Diseases, University of Lund, Lund, Sweden.

Journal of Clinical Microbiology
|February 7, 2001
PubMed

Insights

Group A Streptococcus T28 strains in Sweden have developed resistance to macrolide-lincosamide-streptogramin B (MLS) antibiotics and tetracycline. Pulsed-field gel electrophoresis revealed these antibiotic-resistant strains belong to at least five distinct clones.

Area of Science:

  • Microbiology
  • Molecular Biology
  • Epidemiology

Background:

  • Group A Streptococcus (GAS) T type 28 (T28) strains have been prevalent in southern Sweden.
  • Since 1995, an increase in T28 isolates exhibiting resistance to macrolide-lincosamide-streptogramin B (MLS) antibiotics and tetracycline has been observed.

Purpose of the Study:

  • To investigate the clonal relatedness of antibiotic-resistant T28 strains of Group A Streptococcus.
  • To characterize the genetic basis of antibiotic resistance in these strains.

Main Methods:

  • Extended T typing, emm typing (PCR capture enzyme-linked immunosorbent assay, emm amplicon restriction profiling, emm sequence typing), superantigen gene detection (speA, speB, speC), antibiotic resistance gene analysis (tetM, ermB, mefA) using PCR and hybridization, and pulsed-field gel electrophoresis (PFGE).

Main Results:

  • Ninety-five of 100 tetracycline-resistant strains were T9-T13-T28, predominantly M type 77 (M77).
  • Eighty-nine strains were macrolide resistant, with varying MLS resistance phenotypes (inducible, constitutive, noninducible, novel subphenotypes).
  • Resistance genes tetM, ermB, and mefA were identified corresponding to the observed resistance patterns. PFGE indicated at least five distinct clones among the antibiotic-resistant M77 strains.

Conclusions:

  • The emergence of antibiotic resistance in T28 GAS strains in Sweden is associated with specific M types and is driven by the acquisition of resistance genes like tetM, ermB, and mefA.
  • The presence of multiple clones suggests different evolutionary pathways for antibiotic resistance acquisition in these strains.
  • Continued surveillance is crucial to monitor the spread and evolution of antibiotic-resistant GAS.

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