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Role of adherence in the pathogenesis of neonatal group B streptococcal infection
Insights
Group B Streptococcus type III strains attach better to infant cells than adult cells, especially in infected infants. This suggests infants may have more attachment sites for these virulent bacteria.
Area of Science:
- Microbiology
- Neonatal Infectious Diseases
- Bacterial Pathogenesis
Background:
- Group B Streptococcus (GBS) is a leading cause of invasive infections in neonates.
- Understanding GBS adherence to host cells is crucial for preventing neonatal disease.
- Specific GBS serotypes exhibit varying virulence and adherence properties.
Purpose of the Study:
- To investigate the adherence of different GBS serotypes to buccal epithelial cells from adults, healthy neonates, and infants with invasive GBS infection.
- To determine if GBS adherence correlates with host age and infection status.
- To identify potential mechanisms underlying enhanced GBS attachment in neonates.
Main Methods:
- Use of (3)H-labeled GBS strains incubated with buccal epithelial cells at a 1,000:1 bacteria-to-cell ratio.
- Comparison of adherence levels across different GBS serotypes (Ia, II, III).
- Assessment of adherence to cells from adult volunteers, healthy neonates, and infants with invasive GBS infection.
Main Results:
- Type III GBS adhered significantly better to healthy neonatal cells than adult cells (31 vs. 7 bacteria/cell).
- GBS strains from infected infants showed greater adherence to infected infant cells than control infant cells (39 vs. 18 bacteria/cell).
- No significant differences in adherence were observed for type Ia or II strains between neonates and adults.
Conclusions:
- The most virulent GBS serotype for neonates (type III) exhibits enhanced adherence to neonatal epithelial cells.
- Infants with invasive GBS infection may possess increased epithelial cell receptors for GBS attachment.
- Bacterial products could potentially unmask or enhance receptor sites for GBS adherence in infants.
Abstract:
The ability of group B streptococci to attach to buccal epithelial cells from adult volunteers, healthy neonates, and infants with invasive group B streptococcal infection was assessed by using (3)H-labeled bacteria incubated at a bacteria-to-cells ratio of 1,000:1. Type III group B streptococcal clinical isolates adhered significantly better to the epithelial cells of healthy neonates than to those of adults (mean bacteria per cell of 31 versus 7, respectively; P < 0.005). In contrast, no statistically significant differences in adherence of type Ia or type II strains to cells of neonates and adults were noted. The adherence of strains isolated from 15 infants with invasive group B streptococcal infection was significantly greater to the cells of infected infants than to those of age-matched controls (mean bacteria per cell of 39 versus 18, respectively; P < 0.005). In contrast, no significant difference was noted in the adherence of a usually adherent type Ia strain and a nonadherent type III strain to the cells of infected infants compared with control infants. These results indicate that the serotype of group B streptococci with the greatest virulence for neonates (type III) adheres better to neonatal than to adult epithelial cells. Infants who develop invasive infection may have an increased number of epithelial cell surface receptor sites for attachment of group B streptococci, the bacteria may elaborate products which unmask receptor sites, or both.