Final answer:
The antibiotics used to treat the ear infection disrupted the normal balance of vaginal flora, notably reducing lactobacilli, and thereby allowing the opportunistic fungus Candida to overgrow and cause yeast vaginitis. Other factors that can lead to imbalances and infections include illnesses, hormonal changes, contraception, hygiene practices, and irritants.
Step-by-step explanation:
Your friend's development of yeast vaginitis following antibacterial treatment for an ear infection has a biological explanation. Antibiotics are designed to kill bacteria, including beneficial ones like lactobacilli. These bacteria normally maintain a balanced vaginal environment, preventing the overgrowth of other organisms such as Candida fungi. When lactobacilli are diminished, Candida can proliferate, leading to a yeast infection.
Aside from antibiotic use, several other factors can also alter vaginal pH or disrupt the microbial balance, increasing the risk of bacterial vaginosis (BV) or yeast infections.
It is crucial for individuals on antibiotics to monitor for symptoms like itching, discharge, and odor that could indicate a secondary infection such as BV or yeast vaginitis.