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Capsular Serotyping of Streptococcus pneumoniae by Latex Agglutination
Published on: September 25, 2014
Clonal groups of penicillin-nonsusceptible Streptococcus pneumoniae in Baltimore, Maryland: a population-based,
M C McEllistrem1, M Pass, J A Elliott
1Infectious Diseases Epidemiology Research Unit, University of Pittsburgh Graduate School of Public Health and School of Medicine, Pittsburgh, Pennsylvania 15213, USA. mcellistremc@msx.dept-med.pitt.edu
Abstract:
Few data are available on the molecular subtypes of all penicillin-nonsusceptible Streptococcus pneumoniae (PNSP) from a defined population base. Pulsed-field gel electrophoresis (PFGE), serotyping, and antibiotic susceptibility testing were performed for all available invasive PNSP isolates for which the penicillin (MIC) was > or =0.1 microg/ml from Baltimore, Md., during 1995-1996 (n = 143). The dendrogram analysis of PFGE patterns included 32 distinct clonal groups. Six major clonal groups included two-thirds of the PNSP strains. Major clonal groups 2, 3, 4, and 6 strains were genetically related to four previously described international clones and were all multidrug resistant. Major clonal group 3 was genetically related to the Tennessee(23F)-4 clone and contained all four strains for which the penicillin MIC was 8 microg/ml. Most of the clonal group 1 and 5 strains had intermediate susceptibility to penicillin and were rarely multidrug resistant. The latter clonal groups represent two previously undescribed penicillin-intermediate pneumococcal clones. Clonal group homogeneity was greater for serotype 9V, 19A, and 23F strains than for serotype 6A, 6B, 14, and 19F strains. The classification of PNSP strains into clonal groups is essential for future population-based epidemiologic studies of PNSP.
Insights
Penicillin-nonsusceptible Streptococcus pneumoniae (PNSP) strains were molecularly subtyped using PFGE, revealing distinct clonal groups. Some PNSP clones were multidrug-resistant, while others showed intermediate penicillin susceptibility.
Area of Science:
- Microbiology
- Epidemiology
- Molecular Biology
Background:
- Limited data exist on the molecular epidemiology of penicillin-nonsusceptible Streptococcus pneumoniae (PNSP) in defined populations.
- Understanding PNSP clonal diversity is crucial for public health surveillance and intervention strategies.
Purpose of the Study:
- To characterize the molecular subtypes of invasive PNSP isolates from Baltimore, Maryland, between 1995 and 1996.
- To identify distinct clonal groups and their antibiotic resistance profiles.
Main Methods:
- Pulsed-field gel electrophoresis (PFGE) was used for molecular typing of 143 invasive PNSP isolates.
- Serotyping and antibiotic susceptibility testing were performed to assess resistance patterns and clonal characteristics.
Main Results:
- PFGE analysis identified 32 distinct clonal groups, with six major groups comprising two-thirds of the PNSP strains.
- Multidrug-resistant strains were associated with major clonal groups related to international clones.
- Two novel penicillin-intermediate pneumococcal clones were identified (clonal groups 1 and 5).
- Serotype homogeneity varied among clonal groups, with higher homogeneity for serotypes 9V, 19A, and 23F.
Conclusions:
- PNSP strains exhibit significant molecular diversity, with distinct clonal groups possessing varying resistance profiles.
- Identification of specific clones, including multidrug-resistant and penicillin-intermediate types, is essential for targeted surveillance.
- Molecular subtyping into clonal groups is vital for future population-based epidemiologic studies of PNSP.
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