Close contact with infected people or animals, sneezing, coughing, contact with contaminated food or water, and contact with contaminated surfaces are all ways that bacteria spreads, leading to infections, states WebMD. The elderly, neonates and people with malnutrition are among those at higher risk of bacterial infection, explains Life Extension.
Up to 25 percent of upper respiratory tract infections can be blamed on bacteria, according to Life Extension. An example of a common bacteria is salmonellosis, which is the bacteria to blame for salmonella. Salmonellosis causes more bacterial infections in the United States than almost any other bacteria. This bacteria spreads through exposure to infected reptiles, contaminated food and contaminated water.