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Interspecies recombination contributes minimally to fluoroquinolone resistance in Streptococcus pneumoniae
D J Bast1, J C de Azavedo, T Y Tam
1Department of Microbiology, Toronto Medical Laboratories and Mount Sinai Hospital, Toronto, Canada. dbast@mtsinai.on.ca
Abstract:
Analysis of 71 ciprofloxacin-resistant (MIC > or = 4 microg/ml) Streptococcus pneumoniae clinical isolates revealed only 1 for which the quinolone resistance-determining regions of the parC, parE, and gyrB genes were genetically related to those of viridans group streptococci. Our findings support the occurrence of interspecies recombination of type II topoisomerase genes; however, its contribution to the emergence of quinolone resistance among pneumococci appears to have been minimal.
Insights
Genetic analysis of Streptococcus pneumoniae revealed minimal interspecies recombination contributing to ciprofloxacin resistance. This suggests other mechanisms are more significant in the spread of quinolone resistance in pneumococci.
Area of Science:
- Microbiology
- Genetics
- Antimicrobial Resistance
Background:
- Ciprofloxacin resistance is a growing concern in Streptococcus pneumoniae infections.
- Quinolone resistance-determining regions (QRDRs) in type II topoisomerase genes (parC, parE, gyrB) are key targets for resistance development.
- Interspecies gene transfer can contribute to the emergence of antimicrobial resistance.
Purpose of the Study:
- To investigate the role of interspecies recombination in the development of ciprofloxacin resistance in Streptococcus pneumoniae.
- To analyze the genetic relatedness of QRDRs in resistant pneumococcal isolates to those of other streptococci.
Main Methods:
- Analysis of 71 ciprofloxacin-resistant Streptococcus pneumoniae clinical isolates.
- Sequencing and genetic comparison of the parC, parE, and gyrB genes.
Main Results:
- Only 1 out of 71 resistant isolates showed genetic relatedness in QRDRs to viridans group streptococci.
- This suggests limited interspecies recombination involving these specific genes in the studied pneumococcal population.
- The findings indicate that interspecies recombination of type II topoisomerase genes has a minimal impact on quinolone resistance in pneumococci.
Conclusions:
- Interspecies recombination of type II topoisomerase genes occurs but appears to be a minor factor in the emergence of quinolone resistance among Streptococcus pneumoniae.
- Other mechanisms likely play a more significant role in the dissemination of quinolone resistance in pneumococci.