Lactic acid is a potential virulence factor for group B Streptococcus

Area of Science:

• Microbiology
• Pathogenesis
• Bacterial Virulence Factors

Background:

• Group B Streptococcus (GBS) causes serious infections like sepsis and meningitis in newborns.
• The precise mechanisms behind GBS invasive disease remain incompletely understood.
• Existing knowledge of GBS virulence factors is limited.

Purpose of the Study:

• To investigate novel virulence factors of Group B Streptococcus (GBS).
• To characterize the role of metabolic byproducts in GBS pathogenesis.
• To understand the contribution of GBS-derived substances to tissue damage.

Main Methods:

• Development of a novel in vitro rat fetal lung explant infection model.
• Application of GBS spent growth media and neutralized media to lung explants.
• Utilized viability assays and transformed cell lines for verification.
• Analyzed spent media for organic acid content, specifically l-lactate.

Main Results:

• GBS application to lung explants caused rapid tissue destruction linked to media acidity.
• Neutralizing the spent media completely prevented tissue degradation.
• High levels of l-lactate (approx. 70 mM) were detected in GBS spent media.
• Lactic acid alone induced dose-dependent tissue degradation, confirming its cytotoxic effect.

Conclusions:

• GBS-produced lactic acid functions as a significant virulence factor.
• Lactic acid contributes to the cytotoxicity observed in GBS infections.
• This finding offers new insights into the mechanisms of GBS invasive disease in neonates.