Light micrograph of a vaginal smear from a patient with bacterial vaginosis. An epithelial cell (upper centre) is covered in bacteria giving it a roughened, stippled appearance. This is known as a clue cell, and is characteristic of a bacterial vaginosis infection. Bacterial vaginosis causes an abnormal vaginal discharge with an unpleasant fishy smell. It is caused by an imbalance of the normal vaginal flora. Treatment is with antibiotics.