Coliform bacteria are a broad group of microorganisms found in the environment, including soil, vegetation, and the digestive systems of warm-blooded animals. Their presence often indicates potential health risks, particularly concerning water quality and food safety. This article explores whether these bacteria can cause illness and how to protect against contamination.
What Are Coliform Bacteria?
Coliform bacteria are rod-shaped, Gram-negative, non-spore-forming bacteria that ferment lactose, producing gas within 48 hours at 35°C. This group includes genera such as Escherichia, Klebsiella, Enterobacter, and Citrobacter. These bacteria inhabit diverse environments, thriving in soil, decaying vegetation, and aquatic systems.
Many coliforms live in the intestines of warm-blooded animals, including humans. Their common presence in fecal matter makes them “indicator organisms” for monitoring water and food quality. Detecting coliforms suggests possible fecal contamination, which indicates the potential presence of disease-causing microorganisms. However, their presence does not automatically mean harmful pathogens are also present.
Not All Coliforms Are Harmful
While coliform bacteria indicate potential contamination, many types are harmless and do not cause illness. Some even play a role in healthy human gut function. The broad category of “total coliforms” includes bacteria from various environmental sources, not just feces.
Fecal coliforms, found in the feces of warm-blooded animals, are a more direct indicator of fecal contamination. Escherichia coli (E. coli) is the most common type among these. Most E. coli strains are harmless in the human intestine. However, certain pathogenic strains, such as E. coli O157:H7, are a public health concern. Detecting general coliforms in water or food signals a need for further investigation, as it suggests a higher risk that harmful bacteria might also be present.
Illness Symptoms and Health Risks
Pathogenic strains of coliform bacteria, particularly certain E. coli types, can cause infection leading to gastrointestinal symptoms. These include abdominal cramps, nausea, vomiting, and diarrhea, which can sometimes be bloody depending on the bacterial strain and infection severity.
Illness severity varies from mild discomfort to severe, life-threatening conditions. With E. coli O157:H7 infections, a serious complication called hemolytic uremic syndrome (HUS) can develop. HUS affects the kidneys and blood clotting, potentially leading to kidney failure. Young children, the elderly, and individuals with weakened immune systems are more susceptible to severe illness and complications.
Protecting Against Contamination
Protecting against contamination from harmful coliform bacteria involves hygiene and food safety. Thorough handwashing with soap and water is important after using the restroom, changing diapers, and before and after handling food. This prevents the spread of bacteria from surfaces to food or directly to people.
Safe food handling practices are also important. Meats, especially ground beef, should be cooked to an internal temperature of at least 160°F (71°C) to eliminate harmful bacteria. Prevent cross-contamination in the kitchen by using separate cutting boards and utensils for raw meat and other foods. Fruits and vegetables should be thoroughly washed under running water before consumption.
Ensuring safe drinking water is another protection strategy. Public water systems are regularly tested for coliforms, and advisories, such as boiling water notices, are issued if contamination is suspected. Private well owners should have their water tested annually to ensure it is safe for consumption. If symptoms of illness appear after potential exposure, contact a healthcare professional or local health department.