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Correlation of epithelial cell invasiveness of group B streptococci with clinical source of isolation
P Valentin-Weigand1, G S Chhatwal
1Department of Microbiology, Technical University/GBF-National Research Centre for Biotechnology, Braunschweig, Germany.
Abstract:
Neonatal infections caused by Group B streptococci (GBS) may lead to pneumonia, sepsis, or meningitis indicating that GBS are able to invade tissues and enter the bloodstream from infected sites. In this study, we showed that the tissue invasiveness of GBS may be related to their ability to invade epithelial cells in vitro by correlating the degree of GBS invasion of cultured human respiratory epithelial cells with the clinical source of isolation. Among 77 isolates tested, those from invasive infections of neonates and adults were significantly (P < 0.001) more invasive than those from vaginal carriers and colonised neonates without clinical symptoms. Furthermore, isolates from the blood were more invasive (P < 0.05) than those from other sites. GBS invasion seemed to be mediated by bacterial surface proteins since trypsin treatments of streptococci significantly reduced their invasion into epithelial cells and invasiveness was not limited to a certain capsular serotype. The two major GBS surface protein antigens c and R, however, were not involved in the invasion process. These results indicate that in vitro invasion of cultured human cells reflects the in vivo invasive property of GBS and involves bacterial surface components different from known virulence factors such as capsule or protein antigens c and R.
Insights
Group B Streptococcus (GBS) invasive potential correlates with epithelial cell invasion. Isolates from invasive infections show higher invasiveness, linked to bacterial surface proteins, not capsule or known antigens.
Area of Science:
- Microbiology
- Infectious Diseases
- Bacterial Pathogenesis
Background:
- Group B Streptococcus (GBS) causes severe neonatal infections like pneumonia, sepsis, and meningitis.
- GBS possesses the ability to invade host tissues and enter the bloodstream from infection sites.
Purpose of the Study:
- To investigate the correlation between GBS tissue invasiveness and epithelial cell invasion in vitro.
- To identify bacterial factors contributing to GBS invasion of human respiratory epithelial cells.
Main Methods:
- Cultured human respiratory epithelial cells were used to assess GBS invasion.
- Seventy-seven GBS isolates from various clinical sources were tested for invasion.
- Trypsin treatment of GBS was performed to evaluate the role of surface proteins.
Main Results:
- GBS isolates from invasive infections (neonates, adults) were significantly more invasive than those from carriers (P < 0.001).
- Bloodstream isolates demonstrated higher invasiveness compared to isolates from other sites (P < 0.05).
- Trypsin treatment reduced GBS invasion, indicating involvement of bacterial surface proteins, independent of capsular serotype.
Conclusions:
- In vitro epithelial cell invasion accurately reflects the in vivo invasive properties of GBS.
- GBS invasion involves bacterial surface components distinct from capsule and known protein antigens c and R.
- Understanding these invasion mechanisms is crucial for combating GBS infections.