EVALUATION OF THE DIRECT VIABLE COUNT METHOD FOR TEMPERATURE STRESSEDCAMPYLOBACTER-COLI

Human pathogens, such as campylobacters, transform into the noncultura ble state more or less rapidly in the environment. The question arises , whether these cells are still viable. The direct cell count (DVC) me thod has been used widely for enumeration and viability testing of dif ferent bacterial species. The influence of temperature induced bacteri al injury on the applicability of the method, however, has not been ex amined. Two different Campylobacter coli strains were pre-incubated at low temperatures. The necessary nalidixic acid concentration was stra in specific, and they became more sensitive to the inhibitory effect o f the antibiotic after temperature downshift. The method was not appli cable for cultures that had been pre-incubated at intermediate tempera tures, although nonculturability had not yet set in at the beginning o f the experiments. (C) 1998 Elsevier Science B.V.