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Genetic elements carrying macrolide efflux genes in streptococci

Gianni Pozzi1, Francesco Iannelli, Marco R Oggioni

  • 1Laboratory of Molecular Microbiology and Biotechnology (LAMMB), Department of Molecular Biology, Univeresity of Siena, 53100 Siena, Italy. pozzi@unisi.it

Current Drug Targets. Infectious Disorders
|September 24, 2004
PubMed

Insights

Type M macrolide resistance in Streptococcus species is linked to macrolide efflux genes (mef). These genes are located on three distinct genetic elements, mega, Tn1207.3, and Tn1207.1, each with unique characteristics and transmission capabilities.

Area of Science:

  • Microbiology
  • Genetics
  • Molecular Biology

Background:

  • Type M macrolide resistance in Streptococcus pyogenes and Streptococcus pneumoniae is a significant clinical concern.
  • This resistance is primarily mediated by macrolide efflux genes (mef).

Purpose of the Study:

  • To characterize the conserved chromosomal genetic elements carrying mef genes in Streptococcus species.
  • To understand the mechanisms of macrolide resistance dissemination.

Main Methods:

  • Comparative analysis of genetic elements mega, Tn1207.3, and Tn1207.1.
  • Identification of gene content, integration sites, and transfer mechanisms.

Main Results:

  • Three conserved genetic elements were identified: 'mega' (S. pneumoniae, mef(E)), Tn1207.3 (S. pyogenes, mef(A), conjugative), and Tn1207.1 (defective Tn1207.3, mef(A), non-conjugative).
  • 'mega' integrates at various sites and lacks recombinase genes.
  • Tn1207.3 integrates specifically, possesses recombinase genes, and is conjugative, resembling a bacteriophage.
  • Tn1207.1 is a defective, non-conjugative variant of Tn1207.3 found in S. pneumoniae.

Conclusions:

  • The identified genetic elements play crucial roles in the carriage and potential spread of macrolide resistance in streptococci.
  • Understanding these elements is vital for combating antibiotic resistance in these pathogens.

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