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Recombination rates of Streptococcus pneumoniae isolates with both erm(B) and mef(A) genes

Ji-Young Lee1, Jae-Hoon Song, Kwan Soo Ko

  • 1Department of Molecular Cell Biology, Sungkyunkwan University School of Medicine, Suwon, Korea.

FEMS Microbiology Letters
|July 13, 2010
PubMed

Insights

The simultaneous presence of erm(B) and mef(A) genes in Streptococcus pneumoniae is linked to increased recombination rates. This association may explain the frequent emergence of multidrug resistance (MDR) in these bacterial isolates.

Area of Science:

  • Microbiology
  • Genetics
  • Molecular Biology

Background:

  • Erythromycin resistance in Streptococcus pneumoniae is often mediated by erm(B) and mef(A) genes.
  • Isolates possessing both erm(B) and mef(A) exhibit higher rates of multidrug resistance (MDR).
  • The relationship between specific resistance genes and genetic recombination rates in S. pneumoniae remains underexplored.

Purpose of the Study:

  • To investigate the association between erythromycin resistance determinants (erm(B) and mef(A)) and the recombination frequency in Streptococcus pneumoniae.
  • To determine if the co-occurrence of erm(B) and mef(A) influences mutation and recombination rates.

Main Methods:

  • Determined mutation and recombination frequencies in 46 S. pneumoniae isolates.
  • Categorized isolates based on the presence of erm(B) and/or mef(A) genes, including susceptible controls.
  • Estimated mutation frequency by quantifying rifampin-resistant colonies relative to the total viable count.

Main Results:

  • No significant correlation was observed between the presence of both erm(B) and mef(A) and high mutation frequency.
  • All four isolates exhibiting a hyper-recombination phenotype possessed both erm(B) and mef(A) genes.
  • The recombination rate was statistically higher in isolates with both erm(B) and mef(A) compared to other isolates.

Conclusions:

  • The dual presence of erm(B) and mef(A) genes in S. pneumoniae is strongly associated with a high recombination frequency.
  • This heightened recombination may be a key factor contributing to the frequent emergence of multidrug resistance in certain pneumococcal strains.

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