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Endocarditis caused by a group B Streptococcus strain, type III, in a nonencapsulated phase
M Sellin1, M Linderholm, M Norgren
1Department of Clinical Bacteriology, University of Umeå, Sweden.
Journal of Clinical Microbiology
|September 1, 1992
Summary
A nontypeable group B Streptococcus (GBS) strain causing endocarditis may represent a nonencapsulated phase of a type III GBS. Encapsulated GBS variants can be selected from nonencapsulated strains, challenging classification.
Area of Science:
- Microbiology
- Bacterial Pathogenesis
- Streptococcal Research
Background:
- Group B Streptococcus (GBS) is a significant human pathogen, particularly in neonates.
- Nontypeable GBS strains present diagnostic and classification challenges.
- Endocarditis caused by GBS is a serious infection.
Observation:
- A nontypeable GBS blood isolate from an endocarditis patient was identified.
- This isolate was proposed to be the nonencapsulated phase of a type III GBS strain.
- A low-density, encapsulated phase of the GBS strain was successfully selected using Percoll gradient centrifugation.
Findings:
- The study demonstrates phase variation in GBS, with a transition from nonencapsulated to encapsulated forms.
- Percoll gradient centrifugation is an effective method for isolating encapsulated GBS variants.
- Nontypeable GBS strains may exhibit phenotypic plasticity, including capsule expression.
Implications:
- Classification of GBS strains as truly nontypeable requires careful consideration of potential encapsulated phases.
- Understanding GBS phase variation is crucial for accurate diagnostics and epidemiological studies.
- This finding may impact vaccine development strategies targeting GBS capsule antigens.