Sensitive rapid detection method for viable bacterial cells.

A rapid sensitive method for the detection of viable bacterial cells is described in which P as inorganic orthophosphate is used to label the cells. Factors affecting the uptake of P by cells as well as the sensitivity of the method have been explored with suspensions of Aerobacter aerogenes. The uptake of PO(4) is dependent on several factors. Of various incubation media tested, one composed of 0.005 m KCl, 0.002 m MgSO(4) and 10 mg/ml of glucose was found to best stimulate the uptake of the tracer. Incubation time and temperature and level of isotope and of unlabeled P also affected uptake. Labeled cells were collected on a membrane filter for measurement of radioactivity. Under optimal conditions, as few as 23 viable cells per milliliter were detected in 1 hr with 95% confidence.