Introduction: Group B Streptococcus (GBS), infection and recurrence in newborns and pregnant women can lead to
chronic medical illness resulting in significant morbidity, and mortality. Pathogenesis of GBS may be due to reasons
such as activation of the immune system, followed by the production of inflammatory markers and toxic components
by immune cells including macrophages. Methods: The studies on invasive and colonizing GBS strains inoculated
either with peripheral or brain macrophages, the expression of nitric oxide (NO), cell viability, and CD40 were
also measured by Griess assay, methyl tetrazolium assay (MTT), and flow cytometry, respectively. Furthermore, the
clinical manifestations of the selected patients were also assessed for this study. Results: Outcome of inflammatory
markers studies, after GBS inoculation indicated that, invasive GBS strains induced higher inflammatory markers
in comparison to colonizing GBS strains. Furthermore, patients’ clinical data showed that patients with invasive
GBS infections had severe condition unlike among patients with colonizing GBS strains. The fatality rate in patients
with invasive GBS strain were 30.8% while there was no death among carriers. Conclusion: This study, aimed to
understand the immune response to GBS, and strengthen the knowledge on GBS pathogenesis. It was concluded
that invasive GBS strains not only showed higher expression of inflammatory markers on immune cells but also had
higher pathogenesis effect in comparison to colonizing GBS strains.