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Identification of the major Spanish clones of penicillin-resistant pneumococci via the Internet using multilocus
J Zhou1, M C Enright, B G Spratt
1Wellcome Trust Centre for the Epidemiology of Infectious Disease, Department of Zoology, University of Oxford, Oxford OX1 3FY, United Kingdom.
Abstract:
Multilocus sequence typing was used to characterize isolates of the major Spanish clones of penicillin-resistant and multiple-antibiotic-resistant Streptococcus pneumoniae. Isolates of the multidrug-resistant Spanish serotype 23F clone and serotype variants of this clone either had identical allelic profiles or their allelic profiles differed from this typical allelic profile at only one of the seven housekeeping loci. Similarly, isolates of the Spanish serotype 6B and 14 clones and the penicillin-resistant serotype 9V clone (and serotype variants of this clone) each had the same allelic profiles or profiles that differed at a single locus. Multilocus sequence typing therefore allows resistant pneumococci to be assigned to the Spanish clones if they have the typical allelic profile of the clone or if their profiles differ from that profile at a single locus. A few resistant isolates that had allelic profiles typical of that of a Spanish clone or whose profiles differed from that of the typical profile at only a single locus possessed penicillin-binding protein pbp1a, pbp2b, or pbp2x genes that differed from those that are characteristic of the clone. In most cases these isolates could be assigned as variant members of the clone. Since almost all serotype 9V isolates have very similar genotypes, independently emerging penicillin-resistant clones of this serotype will inevitably appear to be similar by molecular typing procedures. Analysis of the pbp genes, in addition to multilocus sequence typing (or any other molecular typing procedure), is therefore required to assign isolates unambiguously to the penicillin-resistant Spanish serotype 9V clone.
Insights
Multilocus sequence typing effectively identifies Spanish clones of Streptococcus pneumoniae, including resistant strains. Analyzing penicillin-binding protein genes is crucial for unambiguous classification of specific resistant clones like serotype 9V.
Area of Science:
- Microbiology
- Genetics
- Epidemiology
Background:
- Streptococcus pneumoniae is a major cause of bacterial infections.
- Penicillin resistance and multidrug resistance are significant public health concerns.
- Identifying the genetic lineage of resistant strains is crucial for epidemiological tracking.
Purpose of the Study:
- To characterize Spanish clones of Streptococcus pneumoniae resistant to penicillin and multiple antibiotics.
- To evaluate the utility of multilocus sequence typing (MLST) for classifying resistant isolates.
- To determine if additional genetic analysis is needed for specific clones.
Main Methods:
- Multilocus sequence typing (MLST) was performed on isolates of major Spanish clones.
- Allelic profiles of housekeeping genes were analyzed.
- Penicillin-binding protein (pbp) genes (pbp1a, pbp2b, pbp2x) were analyzed in select isolates.
Main Results:
- MLST successfully assigned most resistant isolates to known Spanish clones, with variations at one locus.
- Some resistant isolates possessed divergent pbp genes, classified as variant members of their respective clones.
- Serotype 9V isolates showed high genotypic similarity, potentially obscuring independent resistant clone emergence.
Conclusions:
- MLST is a valuable tool for assigning resistant pneumococcal isolates to Spanish clones.
- Analysis of pbp genes is essential for unambiguous classification, particularly for serotype 9V.
- Combined MLST and pbp gene analysis enhances the molecular epidemiology of resistant Streptococcus pneumoniae.