Light micrograph of a vaginal smear in a case of bacterial vaginosis, also known as anaerobic vaginosis or non-specific vaginitis. The sexually- transmitted infection was first believed to be due to the bacterium Gardnerella vaginalis, but Bacteroides spp. and Mobiluncus spp. are also thought to be implicated. Gram-stained micrographs show the squamous cells that form the vaginal lining densely covered in microorganisms, including curved rod-shaped bacteria, Mobiluncus spp.. The major symptom is a watery, non- irritating discharge which has a fishy odour. The infection responds to metronizadole; male partners are treated concurrently to avoid reinfection.