A-1 Medium

A-1 Medium is used for the detection of coliform organisms in water and food in a laboratory setting. A-1 Medium is not intended for use in the diagnosis of disease or other conditions in humans.

Since the early 1900’s enumeration of coliform organisms, specifically E. coli, have been used to determine water purity. Elevated temperature and most-probable-number (MPN) methods are routinely used for analysis of water and food samples for presence of fecal coliforms. A-1 Medium was formulated to hasten E. coli recovery and reduce the incidence of false positive cultures.

In 1972 Andrews and Presnell developed A-1 Medium. This medium recovers E. coli from estuarine water in 24 hours instead of 72 hours, and in greater numbers without the pre-enrichment step. A-1 Medium can be used in a single step procedure for the detection of fecal coliforms in source water, seawater, treated wastewater, and foods. A-1 Medium conforms to standard methods for the isolation of fecal coliforms in water and foods.