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

Previous studies suggesting that the persistence of thermotolerant Campylobacter in water, especially as a viable but non-cultivable form (VNC), was involved in human campylobacteriosis, the capacities of survival and resuscitation of a significant collection of 85 strains in aqueous microcosms were investigated. Two-thirds of these strains (68%) were not detectable on agar 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 remained cultivable after 35 days in a shaken aqueous microcosm and beyond 60 days without shaking. After 30 days, 51% of the non-detectable strains by conventional culture were recovered after injection in 9-day fertilised chicken eggs. A kinetic study showed that the age of the viable but non-cultivable 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 animals and that an embryonic factor seems to be essential to allow resuscitation.