The Role of Microbiome in Sexually Transmitted Infections

Abstract

Background: Several studies have shown that abnormal vaginal flora associated with sexually transmitted infections (STIs). Content: Microbiome can be defined as an ecological community of commensal, symbiotic, and pathogenic microorganisms that literally share the living in human body space. Studies showed that uncircumcised men are more likely to be populated by gram-positive and negative bacteria or other pathogens. The vaginal community is grouped into five microbiomes: community-state type (CST) I is dominated by L. crispatus; CST II by L. gasseri; CST III by L. iners; and CST V by L. jensenii. Whereas CST IV is heterogeneous and characterized by higher proportion of obligate anaerobic bacteria. Lactobacillus produces lactic acid and bacteriocin, which contribute to prevent bacterial growth by maintaining a low vaginal pH (pH 3.0 - 4.5). Bacterial vaginosis (BV) is a syndrome that occurs due to dysbiosis in vaginal microbiome. The protective mechanism by Lactobacillus compromises in BV, which becomes an entry point for pathogenic organisms. Protection against C. trachomatis infection is mainly generated by lactic acid produced by Lactobacillus. The low pH is also known to inhibit the survival of N. gonorrhoeae. Protection mechanism by Lactobacillus against viral infections such as HIV, HSV-2, and HPV can occur direct or indirectby several complex and integrated mechanisms. Conclusion: microbiome-based approaches have promising outcomes for both preventive and curative measures for sexually transmitted infections.