Campylobacter hepaticus, the cause of Spotty Liver Disease in chickens, can enter a viable but nonculturable state

Abstract

Campylobacter hepaticus causes Spotty Liver Disease (SLD) in layer hens, resulting in mortality and productivity losses. Like other Campylobacter species, C. hepaticus is a fastidious organism that requires microaerobic conditions to grow and efficiently replicate. Despite its apparent vulnerability to environmental conditions, it is suspected that there are environmental sources of C. hepaticus that cause infections in chickens newly placed in production houses. Although C. hepaticus DNA has been detected in insects, rodent and wild bird droppings, and in environmental samples such as water and soil, it has not been possible to culture C. hepaticus from these sources. Therefore, it is unclear whether these environments harbor viable bacteria or the remnants of dead bacteria. Determining the viability of C. hepaticus in challenging conditions has implications for understanding the potential relevance of environmental reservoirs and routes of transmission. Other Campylobacters are known to enter viable but nonculturable (VBNC) states that result in prolonged survival in hostile environmental conditions. This study has demonstrated that C. hepaticus can also enter a VBNC state when stored in water or a simple salt solution (Ringer’s solution). Cells in the VBNC state could not be recovered on media normally used for primary isolation, but media modifications were tested, and a ‘resuscitation’ media was developed. VBNC cells could be recovered from Ringer’s solution stored at 4 °C for up to 112 days. VBNC cells are postulated to play an important role in the epidemiology of SLD.