What is the most common pathogen responsible for bacterial vaginosis?

The most common pathogen responsible for bacterial vaginosis is Gardnerella vaginalis. This organism is part of a group of anaerobic bacteria that can overgrow when the normal vaginal flora is disrupted. In bacterial vaginosis, there is a decrease in the number of Lactobacillus species, which are important for maintaining a healthy vaginal environment, coupled with an overabundance of other bacteria, including Gardnerella vaginalis.

While Lactobacillus crispatus is generally associated with a healthy vaginal microbiome and helps to keep the pH low, its reduction is a hallmark of bacterial vaginosis. Staphylococcus aureus is not typically associated with this condition and is more often linked to other types of infections, particularly skin infections. Neisseria gonorrhoeae is a sexually transmitted pathogen and causes gonorrhea, which is a different type of infection entirely and not related to bacterial vaginosis.

Thus, Gardnerella vaginalis stands out as the key organism in the context of bacterial vaginosis due to its role in the shift of the vaginal flora that characterizes this imbalance.