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[Beta-lactam and macrolide resistance in Streptococcus pneumoniae]
1Pharmaceutical Research Center, Meiji Seika Kaisha, Ltd.
Abstract:
The resistance of beta-lactam antibiotics in penicillin-resistant Streptococcus pneumoniae (PRSP) is due to alterations in penicillin-binding proteins(PBPs). Recently, highly beta-lactam-resistant strains(MIC: > or = 4 micrograms/ml for penicillin, > or = 8 micrograms/ml for ampicillin, and > or = 4 micrograms/ml for cefotaxime) have been isolated. High resistance of these strains is caused by further alterations in pbp2x and pbp2b genes adjacent to conserved amino acid motifs, in addition to that detected in common PRSP. The resistant mechanisms of macrolides in S. pneumoniae is recognized as production of a 23s rRNA methylase encoded by ermB and efflux system mediated by mefA gene. We detected these genes by PCR in clinical isolates, and showed the relationship between the presence of each gene and the susceptibilities of 14-, 15-, 16-membered macrolides.
Insights
Penicillin-resistant Streptococcus pneumoniae strains show high resistance to beta-lactam antibiotics due to altered penicillin-binding proteins. Macrolide resistance mechanisms involve specific genes, ermB and mefA, linked to reduced susceptibility.
Area of Science:
- Microbiology
- Molecular Biology
- Genetics
Context:
- Streptococcus pneumoniae is a leading cause of bacterial infections.
- Antibiotic resistance in S. pneumoniae poses a significant public health threat.
- Penicillin-resistant S. pneumoniae (PRSP) exhibits resistance to beta-lactam antibiotics.
Purpose:
- To investigate the genetic basis of high-level beta-lactam resistance in S. pneumoniae.
- To identify the prevalence of macrolide resistance genes (ermB and mefA) in clinical isolates.
- To correlate the presence of these genes with macrolide susceptibility profiles.
Summary:
- Highly resistant S. pneumoniae strains possess further alterations in pbp2x and pbp2b genes, beyond those in common PRSP.
- Detection of ermB and mefA genes via PCR in clinical isolates.
- Established a relationship between ermB/mefA gene presence and susceptibility to 14-, 15-, and 16-membered macrolides.
Impact:
- Provides insights into the molecular mechanisms of antibiotic resistance in S. pneumoniae.
- Informs clinical treatment strategies for S. pneumoniae infections.
- Contributes to understanding the evolution and spread of antibiotic resistance genes.