Differential Interaction between Invasive Thai Group B Streptococcus Sequence Type 283 and Caco-2 Cells

Area of Science:

• Microbiology
• Infectious Diseases
• Epidemiology

Background:

• Invasive Group B Streptococcus (GBS) infections, particularly sequence type (ST) 283, are emerging in Southeast Asia.
• Fish consumption is a suspected source for ST283 GBS transmission to humans.

Purpose of the Study:

• To investigate the invasive potential and gastrointestinal tract (GIT) interaction of GBS ST283 isolates.
• To determine if phenotypic variations in invasiveness correlate with patient age.

Main Methods:

• Genotyping of 55 GBS clinical isolates to identify ST and capsular polysaccharide type (CPS).
• In vitro interaction studies using Caco-2 intestinal epithelial monolayers with selected ST283/CPSIII isolates.
• Assessment of invasion efficiency, intracellular survival, and Caco-2 monolayer translocation.

Main Results:

• 33 out of 44 invasive GBS isolates were identified as ST283/CPSIII, with 15 from young adults (16-36 years).
• ST283/CPSIII isolates showed age-dependent invasion efficiency and intracellular survival in Caco-2 cells.
• All isolates translocated across Caco-2 monolayers, but timing varied, suggesting GIT invasion potential.

Conclusions:

• GBS ST283 exhibits potential for invasion via the gastrointestinal tract.
• Phenotypic variations in GBS invasiveness, survival, and translocation exist between isolates from young adults and the elderly.
• These findings highlight age-specific differences in GBS pathogenesis and potential transmission routes.