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Group B streptococcal colonization and serotype-specific immunity in healthy elderly persons
Morven S Edwards1, Marcia A Rench, Debra L Palazzi
1Section of Infectious Diseases, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030, USA. morvene@bcm.tmc.edu
Summary
Elderly adults have similar group B Streptococcus (GBS) colonization rates but are more likely to carry type V GBS. They also have lower antibody levels against type V, suggesting a need for type V inclusion in GBS vaccines.
Area of Science:
- Microbiology
- Immunology
- Epidemiology
Background:
- Group B Streptococcus (GBS) disease poses an increasing burden on elderly individuals.
- Colonization rates and protective antibody prevalence against GBS in this demographic are not well-defined.
Purpose of the Study:
- To determine GBS colonization rates in elderly persons.
- To analyze the distribution of GBS capsular polysaccharide (CPS) types.
- To quantify CPS-specific antibody levels in this population.
Main Methods:
- Cross-sectional survey in an outpatient Houston setting.
- Self-obtained vaginal, rectal, and urine specimens for GBS colonization assessment.
- Enzyme-linked immunosorbent assays (ELISAs) for quantifying CPS-specific IgG antibodies.
Main Results:
- GBS colonization rate was 21.7% among 254 healthy elderly participants (mean age, 73 years).
- Predominant CPS types were V (47.3%), Ia (22.8%), and III (12.3%).
- Low geometric mean concentrations of CPS-specific IgG were observed, significantly lower for type V.
Conclusions:
- Elderly individuals are colonized with GBS at rates similar to younger populations.
- Older adults show a higher prevalence of type V GBS carriage and reduced type V CPS-specific IgG.
- Inclusion of type V CPS in GBS vaccines is recommended for protecting the elderly against invasive disease.