During Drug Therapy for Pneumonia,a Female Patient Develops a Vaginal

During drug therapy for pneumonia,a female patient develops a vaginal superinfection.The nurse explains that this infection is caused by:

A) large doses of antibiotics that kill normal flora.
B) the infection spreading from her lungs to the new site of infection.
C) resistance of the pneumonia-causing bacteria to the drugs.
D) an allergic reaction to the antibiotics.