A most probable number method for estimating small numbers of campylobacters in water.

A most probable number (MPN) method capable of estimating as few as ten campylobacters per 100 ml of water is described. The method gave results close to those obtained by the viable count method of Miles, Misra & Irwin (1938) with graded suspensions of Campylobacter jejuni. The method was used to test raw water samples: counts were obtained ranging from 10 to 230 campylobacters per 100 ml for 11 49 coastal and estuary water samples, and from 10 to 36 campylobacters per 100 ml for 7 of 44 river samples. Campylobacters were isolated from an additional 24 of the 'negative' samples by testing 200 ml volumes by glass microfibre filtration and enrichment culture methods. The MPN method should prove to be a useful epidemiological tool particularly suited to the enumeration of campylobacters in particulate fluids.