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Penicillin-resistant Streptococcus pneumoniae strains recovered in Houston: identification and molecular
J Versalovic1, V Kapur, E O Mason
1Dept. of Pathology, Baylor College of Medicine, Houston, TX 77030.
Abstract:
A sample of 48 penicillin-resistant Streptococcus pneumoniae (PRSP) strains recovered between January 1989 and May 1991, primarily from infected children in Houston, was characterized by multilocus enzyme electrophoresis and repetitive extragenic palindromic-polymerase chain reaction genomic profiling. A heterogeneous array of 22 clonal genotypes was identified, but 64% of the PRSP strains in the sample were assigned to five clones that are closely similar in overall chromosomal character and express serotype 6 capsule. A close genetic association between these five clones and penicillin-resistant 6B clones recovered in Alaska, Iceland, and Spain was identified by multilocus enzyme electrophoresis. Taken together, the results suggest either that the common resistant 6B clones in Alaska, Iceland, Spain, and Houston have a recent ancestor or that isolates of a certain pneumococcal phylogenetic lineage are more likely to develop penicillin resistance.
Insights
Penicillin-resistant Streptococcus pneumoniae (PRSP) strains show diverse genetic profiles, with five dominant clones linked to serotype 6. These clones share genetic links with resistant strains globally, suggesting a common ancestor or lineage predisposition to resistance.
Area of Science:
- Microbiology
- Genetics
- Epidemiology
Background:
- Penicillin resistance in Streptococcus pneumoniae is a growing public health concern.
- Understanding the genetic diversity and clonal expansion of resistant strains is crucial for effective treatment and control.
Purpose of the Study:
- To characterize the genetic makeup of penicillin-resistant Streptococcus pneumoniae (PRSP) strains.
- To identify clonal genotypes and their geographical distribution.
- To investigate potential genetic links between PRSP strains from different regions.
Main Methods:
- Multilocus enzyme electrophoresis (MEE) for genetic profiling.
- Repetitive extragenic palindromic-polymerase chain reaction (REP-PCR) for genomic fingerprinting.
- Analysis of 48 PRSP strains collected between 1989 and 1991.
Main Results:
- Identified 22 distinct clonal genotypes among the PRSP strains.
- 64% of strains belonged to five major clones, characterized by similar chromosomal features and serotype 6 capsule expression.
- MEE revealed a close genetic association between these Houston-based clones and penicillin-resistant serotype 6B clones from Alaska, Iceland, and Spain.
Conclusions:
- The findings suggest a recent common ancestor for widespread penicillin-resistant serotype 6B clones.
- Alternatively, specific pneumococcal phylogenetic lineages may possess a higher propensity for developing penicillin resistance.
- These insights are vital for tracking antimicrobial resistance patterns and informing therapeutic strategies.