Koliformseid

Koliformseid, or coliforms, is a group of Gram-negative, non-spore-forming, facultatively anaerobic, rod-shaped bacteria. They ferment lactose with acid and gas within 24 to 48 hours at 35°C. Coliforms are primarily members of the Enterobacteriaceae family and include genera such as Escherichia, Klebsiella, Enterobacter, and Citrobacter. They are widely used as indicator organisms in water quality testing because their presence suggests fecal contamination and the possible presence of enteric pathogens, rather than being a single pathogen themselves.

A subset called fecal or thermotolerant coliforms can grow at higher temperatures, typically 44.5°C, and includes Escherichia coli, the most common fecal indicator organism in water testing. Detection is performed by methods such as membrane filtration, multiple-tube fermentation (MPN), or rapid enzymatic tests that detect β-galactosidase activity. Distinguishing fecal coliforms from the broader group helps focus assessment on recent fecal contamination.

Health and regulatory relevance: Most coliforms are not pathogens, but their presence signals possible contamination with fecal material and potential pathogens like viruses, Giardia, or Cryptosporidium. Therefore, positive results often lead to confirmatory testing for fecal indicators and pathogens, source investigations, and management actions in water systems or food processing where sanitation matters. Standards vary by country, but many jurisdictions require zero or very low coliform counts in drinking water and use coliform presence as an initial safety screen for recreational waters and foods.

Notes: The term coliform refers to a functional group defined by lactose fermentation and gas production in lactose-containing media. The group is ecologically diverse, including environmental species that may be present in soil, plants, and water. Modern monitoring often combines coliform testing with more specific fecal indicators such as E. coli and Enterococcus.