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Fluoroquinolone resistance in invasive Streptococcus pyogenes isolates due to spontaneous mutation and horizontal

M W R Pletz1, L McGee, C A Van Beneden

  • 1Department of Global Health, Rollins School of Public Health, Emory University, Atlanta, Georgia, USA. pletz.mathias@mh-hannover.de

Antimicrobial Agents and Chemotherapy
|February 24, 2006
PubMed

Insights

Fluoroquinolone resistance in Streptococcus pyogenes is rare but documented. One isolate acquired resistance via horizontal gene transfer from Streptococcus dysgalactiae, while another developed spontaneous mutation.

Area of Science:

  • Microbiology
  • Genetics
  • Antimicrobial Resistance

Background:

  • Fluoroquinolone resistance in Streptococcus pyogenes is infrequently reported.
  • Understanding resistance mechanisms is crucial for effective treatment of S. pyogenes infections.

Observation:

  • Two invasive, ciprofloxacin-resistant S. pyogenes isolates were analyzed.
  • Genetic sequencing focused on quinolone resistance-determining regions of gyrA and parC.

Findings:

  • Both isolates possessed an S79F mutation in parC, conferring fluoroquinolone resistance.
  • One isolate exhibited a D91N mutation in parC and evidence of interspecies recombination with Streptococcus dysgalactiae.
  • Phylogenetic analysis and recombination testing confirmed horizontal gene transfer of a 90-bp sequence containing the S79F mutation from S. dysgalactiae.
  • The second isolate's resistance was attributed to spontaneous mutation, with its susceptible ancestor identified.

Implications:

  • This study provides evidence of fluoroquinolone resistance acquisition in S. pyogenes through both horizontal gene transfer and spontaneous mutation.
  • The findings highlight the potential for interspecies recombination to contribute to antimicrobial resistance in bacterial pathogens.
  • Understanding these distinct resistance pathways is vital for surveillance and management strategies against S. pyogenes.

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