Final answer:
The disadvantages of normal flora include vulnerability to infections by antibiotic-resistant bacteria like Clostridium difficile, increased skin infections due to imbalance, and susceptibility to yeast infections in the vagina after antibiotics disrupt the natural microbiota.
Step-by-step explanation:
Normal flora, or the microbiota that inhabit various parts of our bodies, play a crucial role in human health. However, there are several disadvantages when their balance is disrupted. Overuse of antibiotics can lead to the decimation of normal gut bacteria, allowing for the overgrowth of antibiotic-resistant bacteria such as Clostridium difficile. This can result in severe gastric issues like chronic diarrhea and also make the body more susceptible to infections by other microorganisms due to the vacated niches. Biofilms formed by bacteria can resist antibiotics, making infections more difficult to treat.
Mutual existence of different microbial species on the skin prevents infections, but if this balance is disturbed, it can lead to the dominance of a single species such as yeast, resulting in skin infections. Additionally, the disruption of normal vaginal flora like Lactobacillus can increase the pH of the vagina, favoring the growth of pathogenic yeasts. The excessive processing of foods and decline in natural fermentation may also harm the diverse microbial environment in the intestine which is essential for digestion and preventing disease.