Type I is characterized by the dominance of Lactobacillus crispatus. In the vagina Lactobacillus crispatus is a beneficial bacterium that produces L- and D-lactic acids which keep the vaginal pH low. Lactobacillus crispatus also doesn’t play well with other bacteria which means that it is very effective in preventing pathogens from thriving. Women microflora belonging to this Community State Type have a healthy vaginal microbiome and are known to have the lowest risk of health complications such as bacterial vaginosis, recurrent urinary tract infections and preterm birth.
Type II microbiome is dominated by Lactobacillus gasseri. Lactobacillus gasseri produces D-lactic acid and slightly less L-lactic acid. Overall, Lactobacillus gasseri is still very good at keeping the pH of the vagina low and harmful bacteria away. Women with Type II vaginal microbiome have a healthy vaginal microbial community and the risks for bacterial vaginosis, recurrent urinary tract infections and pelvic inflammatory diseases are low.
Type III is characterized by the dominance of Lactobacillus iners. Lactobacillus iners is a controversial bacterium. It produces L-lactic acid but it is not as efficient as L. crispatus or L. gasseri in keeping the vaginal pH low. Therefore, it is not as protective against potential pathogens and can coexist with both healthy and disruptive bacteria. Type III community state is considered healthy.
Type IV Communty State category is the most diverse one. This type of vaginal microbiomes are not dominated by Lactobacilli and are found in both women with bacterial vaginosis and healthy asympthomatic women.
As Type IV microbiome group is not uniform, it can be associated with women without any concernes and those with recurrent infections and bacterial vaginosis, it cannot be distinctly labeled as healthy or unhealthy. However, not having high abundance of protective Lactobacilli makes vaginal microbiome less stable and those with Type IV microbiome more prone to gynecological and vaginal infections and disorders.
Type V vaginal microbiome is dominated by Lactobacillus jensenii. Lactobacillus jensenii produces D-lactic acid and is very effective in repelling other microbes. It is the rarest microbiome type found in the studies but it is healthy. Women with Type V vaginal microbiome have low risks of bacterial vaginosis and urinary tract infections.
| Vaginal microbiome group (Community State Type) | Dominant bacterial species | Role of microbes in vaginal microbiome |
|---|---|---|
| Type I | Lactobacillus crispatus | Usually Protective |
| Type II | Lactobacillus gasseri | Usually Protective |
| Type III | Lactobacillus iners | Neutral |
| Type IV | Dysbiosis, no dominant species | Usually Disruptive |
| Type V | Lactobacillus jensenii | Usually Protective |
