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Serotype 19f multiresistant pneumococcal clone harboring two erythromycin resistance determinants (erm(B) and mef(A))
L McGee1, K P Klugman, A Wasas
1MRC/SAIMR/WITS Pneumococcal Diseases Research Unit, South African Institute for Medical Research, Johannesburg, South Africa. lesmcgee@hotmail.com
Abstract:
One hundred eighteen erythromycin-resistant Streptococcus pneumoniae (ERSP) strains (MICs of > or = 0.5 microg/ml) from five laboratories serving the private sector in South Africa were analyzed for the genes encoding resistance to macrolides. Sixty-seven ERSP strains (56.8%) contained the erm(B) gene, and 15 isolates (12.7%) contained the mef(A) gene. Thirty-six isolates (30.5%) harbored both the erm(B) and mef(A) genes and were highly resistant to erythromycin and clindamycin. DNA fingerprinting by BOX-PCR and pulsed-field gel electrophoresis identified 83% of these strains as belonging to a single multiresistant serotype 19F clone.
Insights
Eighty-three percent of erythromycin-resistant Streptococcus pneumoniae strains in South Africa belong to a single multiresistant clone. These strains frequently carry erm(B) and mef(A) genes, conferring high-level resistance to macrolides.
Area of Science:
- Microbiology
- Genetics
- Public Health
Background:
- Erythromycin-resistant Streptococcus pneumoniae (ERSP) poses a significant public health challenge.
- Understanding the genetic basis of macrolide resistance in S. pneumoniae is crucial for effective treatment strategies.
Purpose of the Study:
- To investigate the prevalence of macrolide resistance genes (erm(B) and mef(A)) in ERSP strains from South Africa.
- To characterize the genetic relatedness of these resistant strains using DNA fingerprinting techniques.
Main Methods:
- Analysis of 118 ERSP strains from South African private laboratories.
- Detection of erm(B) and mef(A) genes using molecular methods.
- DNA fingerprinting via BOX-PCR and pulsed-field gel electrophoresis (PFGE).
Main Results:
- 67.8% of ERSP strains harbored the erm(B) gene, and 12.7% carried the mef(A) gene.
- 30.5% of isolates contained both erm(B) and mef(A), exhibiting high resistance to erythromycin and clindamycin.
- 83% of these multiresistant strains were identified as a single serotype 19F clone through DNA fingerprinting.
Conclusions:
- A dominant multiresistant serotype 19F clone of Streptococcus pneumoniae is prevalent in South Africa.
- The co-occurrence of erm(B) and mef(A) genes contributes to high-level macrolide resistance in these strains.
- Molecular surveillance and genetic characterization are essential for tracking antimicrobial resistance patterns.