Bacteria are a form of tiny germ that thrive is certain environments. Bacteria can reproduce outside or inside the body given the right conditions and in worse cases will cause infections. The body harbors healthy bacteria in places such as the intestines or vagina. When conditions are optimal for unhealthy bacteria growth, levels of healthy bacteria can be diminished.
Most bacteria thrive in temperatures around 98.6 degrees, the normal temperature of the human body. The National Digestive Diseases Information Clearinghouse notes that harmful bacteria are the most common cause of food-borne illness with the temperature being one factor that promotes growth. Bacteria multiply quickly when food is left out at room temperature; this is undetected by the naked eye. Bacterial contamination by Escherichia coli, or E. coli, and Salmonella cause symptoms of cramping, nausea or diarrhea.
Bacteria require a certain pH level, or acidity to thrive. In women, the vagina maintains a high level of acidity, which prevents bacteria and yeast from growing. The American Academy of Family Physicians explains that when the vagina loses acidity due to hormone changes, use of antibiotics or feminine products, this can encourage bacterial growth. Treatment for this type of bacterial infection is usually in the form of an antibiotic or anti-fungal medication.
Bacteria require a certain amount of moisture to grow. Botulism bacteria are organisms that thrive in moisture and form spores. This means that when conditions are dry, the bacteria may lie dormant. When moisture returns, however, the spores activate, resulting in bacterial growth. According to Merck Manuals Online Medical Library, the reproduction of this bacteria is highly toxic and in severe cases, lethal.