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Published on: September 11, 2020
Genomic analysis of penicillin-resistant Streptococcus pneumoniae in Southeastern Michigan
Elizabeth K Yee1, Lyla J Melkerson-Watson, Craig A Bloch
1Divisions of Pediatric Infectious Diseases, Department of Pediatrics University of Michigan, Ann Arbor, MI 48109-0244, USA.
Objective:
The emergence of multidrug resistance within Streptococcus pneumoniae population was analysed, correlating penicillin resistance Pen(R) with secondary antibiotic resistance, capsular serotype, and genetic diversity among isolates.
Methods:
DNA fingerprinting, following macro-restriction enzyme digestion and pulse field gel electrophoresis (PFGE), and restriction fragment analysis of the PBP 2b gene, following PCR amplification, were performed on the Pen(R) S. pneumoniae, among 377 clinical isolates obtained from the clinical microbiology laboratory (University of Michigan Medical Center).
Results:
Overall 35% of the isolates were Pen(R) of which 45% demonstrated high-level penicillin (Pen(R)-R, MIC>1). Respiratory isolates were more likely to be Pen(R) (p <0.001) than non-respiratory isolates and the rate of Pen(R)-R was significantly increased in children <10 years of age (59.6%, p <0.02). Secondary antibiotic resistance was more frequently associated with Pen(R)-R. Genomic DNA fingerprinting analysis and restriction fragment analysis of the PBP 2b gene demonstrated genomic divergence with discrete conserved pattern in the PBP 2b gene among the resistant isolates.
Conclusion:
The emergence of multidrug resistance in the S. pneumoniae population in SE Michigan is not due to expansion of a single or limited number of resistant clones, is occurring most frequently in the paediatric population and is associated with a decreased susceptibility to penicillin.
Insights
Multidrug resistance in Streptococcus pneumoniae is increasing, particularly in children, and is linked to penicillin resistance. This resistance is not driven by a few clones but shows genetic diversity.
Area of Science:
- Microbiology
- Genetics
- Epidemiology
Background:
- Multidrug resistance (MDR) in Streptococcus pneumoniae is a growing public health concern.
- Penicillin resistance (Pen(R)) is a key indicator of MDR in S. pneumoniae.
- Understanding the factors driving resistance, such as secondary antibiotic resistance and genetic diversity, is crucial.
Purpose of the Study:
- To analyze the emergence of MDR in S. pneumoniae.
- To correlate penicillin resistance with secondary antibiotic resistance, capsular serotype, and genetic diversity.
- To investigate the population dynamics of resistant S. pneumoniae isolates.
Main Methods:
- Analyzed 377 clinical isolates of S. pneumoniae.
- Utilized DNA fingerprinting with macro-restriction enzyme digestion and pulse field gel electrophoresis (PFGE).
- Performed restriction fragment analysis of the PBP 2b gene after PCR amplification.
Main Results:
- 35% of isolates were penicillin-resistant (Pen(R)), with 45% showing high-level resistance.
- Penicillin resistance was more common in respiratory isolates and in children under 10.
- Genomic DNA fingerprinting and PBP 2b gene analysis revealed genomic divergence and conserved patterns in resistant isolates.
- Secondary antibiotic resistance was frequently associated with high-level penicillin resistance.
Conclusions:
- The emergence of MDR in S. pneumoniae in SE Michigan is not due to the expansion of a few resistant clones.
- Resistance is most prevalent in the pediatric population.
- Increased penicillin resistance is associated with decreased susceptibility to penicillin and secondary antibiotic resistance.
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