A 25-year-old pregnant patient with vaginal irritation likely has vaginosis caused by which organism?

Vaginosis, particularly bacterial vaginosis, is most commonly associated with an imbalance in the normal flora of the vagina, often characterized by an increase in certain types of bacteria. Gardnerella vaginalis is a key organism involved in this condition. It is prevalent in cases of bacterial vaginosis and is responsible for the characteristic symptoms, including vaginal irritation and discharge.

In bacterial vaginosis, there is a reduction in the lactobacilli that typically maintain a healthy vaginal environment, leading to an overgrowth of species such as Gardnerella vaginalis. This organism is not a traditional pathogen but is associated with dysbiosis and contributes to the clinical presentation of vaginosis.

Other organisms listed, such as Group B streptococci, Staphylococcus aureus, and Staphylococcus saprophyticus, play different roles in infections and conditions unrelated to bacterial vaginosis. Group B streptococci, for example, are more commonly associated with neonatal infections and urinary tract infections in pregnant women. Staphylococcus aureus and Staphylococcus saprophyticus are known for causing skin infections and urinary tract infections, respectively, but are not key contributors to bacterial vaginosis. Therefore, Gardnerella vaginalis is the correct