Survival and recovery of viable but noncultivable forms of Campylobacter in aqueous microcosm

Previous studies suggesting that the persistence of thermotolerant Campylob acter in water, especially as a viable but non-cultivable form (VNC), was i nvolved in human campylobacteriosis, the capacities of survival and resusci tation of a significant collection of 85 strains in aqueous microcosms were investigated. Two-thirds of these strains (68%) were not detectable on aga r medium after a stay of 14-21 days, whereas 21% reached this state before 14 days and 11% were non-cultivable after a stay of 21 days. Some strains r emained cultivable after 35 days in a shaken aqueous microcosm and beyond 6 0 days without shaking. After 30 days, 51% of the non-detectable strains by conventional culture were recovered after injection in 9-day fertilised ch icken eggs. A kinetic study showed that the age of the viable but non-culti vable forms and characteristics of the strains could explain the variations of recovery. These results suggest that viable but non-cultivable forms of Campylobacter could be a potential risk of colonisation of human or animal s and that an embryonic factor seems to be essential to allow resuscitation . (C) 2000 Elsevier Science BSI. All rights reserved.