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Tetracycline and macrolide co-resistance in Streptococcus pyogenes: co-selection as a reason for increase in

Hans Ulrik K Nielsen1, Anette M Hammerum, Kim Ekelund

  • 1Statens Serum Institut, 2300 Copenhagen S, Denmark. hun@ssi.dk

Microbial Drug Resistance (Larchmont, N.Y.)
|September 24, 2004
PubMed

Insights

Macrolide resistance in Streptococcus pyogenes is low in Denmark, often linked with tetracycline resistance genes. Combined macrolide and tetracycline use significantly correlates with macrolide-resistant S. pyogenes (MRSP) development.

Area of Science:

  • Microbiology
  • Molecular Biology
  • Epidemiology

Background:

  • Tetracycline resistance is common in Danish Streptococcus pyogenes, while macrolide resistance is infrequent.
  • Macrolide-resistant S. pyogenes (MRSP) isolates were studied to understand resistance mechanisms and correlations with antibiotic use.
  • International data was analyzed to investigate the link between macrolide and tetracycline usage and macrolide resistance.

Purpose of the Study:

  • To investigate the genetic basis of tetracycline and macrolide resistance in MRSP.
  • To examine the correlation between macrolide and tetracycline use and the prevalence of macrolide resistance in S. pyogenes.

Main Methods:

  • 133 MRSP isolates collected between November 2000 and November 2002 were analyzed.
  • Macrolide resistance genes (erm(B), erm(A), mef(A)) and tetracycline resistance genes (tet(M), tet(O)) were detected using molecular methods.
  • Statistical analysis was performed to correlate antibiotic usage patterns with macrolide resistance.

Main Results:

  • The macrolide resistance genes erm(B), erm(A), and mef(A) were found in 46%, 18%, and 32% of MRSP isolates, respectively.
  • Tetracycline resistance, mediated by tet(M) or tet(O), was present in 52% of MRSP isolates, frequently associated with erm(B) and mef(A).
  • A significant correlation was observed between the combined use of macrolides and tetracyclines and the development of macrolide resistance in S. pyogenes (p = 0.03).

Conclusions:

  • Macrolide resistance in Danish S. pyogenes is primarily driven by erm genes.
  • The high frequency of macrolide-tetracycline co-resistance suggests tetracycline use is a significant co-factor in selecting for MRSP.
  • Antibiotic stewardship programs should consider the impact of tetracycline use on macrolide resistance in S. pyogenes.

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