Genome Reduction for Niche Association in Campylobacter Hepaticus, A Cause of Spotty Liver Disease in Poultry.

The term "spotty liver disease" (SLD) has been used since the late 1990s for a condition seen in the UK and Australia that primarily affects free range laying hens around peak lay, causing acute mortality and a fall in egg production. A novel thermophilic SLD-associated Campylobacter was reported in the United Kingdom (UK) in 2015. Subsequently, similar isolates occurring in Australia were formally described as a new species, Campylobacter hepaticus. We describe the comparative genomics of 10 C. hepaticus isolates recovered from 5 geographically distinct poultry holdings in the UK between 2010 and 2012. Hierarchical gene-by-gene analyses of the study isolates and representatives of 24 known Campylobacter species indicated that C. hepaticus is most closely related to the major pathogens Campylobacter jejuni and Campylobacter coli. We observed low levels of within-farm variation, even between isolates collected over almost 3 years. With respect to C. hepaticus genome features, we noted that the study isolates had a ~140 Kb reduction in genome size, ~144 fewer genes, and a lower GC content compared to C. jejuni. The most notable reduction was in the subsystem containing genes for iron acquisition and metabolism, supported by reduced growth of C. hepaticus in an iron depletion assay. Genome reduction is common among many pathogens and in C. hepaticus has likely been driven at least in part by specialization following the occupation of a new niche, the chicken liver.

Corrigendum: Genome Reduction for Niche Association in Campylobacter Hepaticus, A Cause of Spotty Liver Disease in Poultry.

[This corrects the article on p. 354 in vol. 7, PMID: 28848714.].

Isolation of a novel thermophilic Campylobacter from cases of spotty liver disease in laying hens and experimental reproduction of infection and microscopic pathology.

The condition known as spotty liver disease or spotty liver syndrome can cause significant mortality in free range laying hen flocks. It has been described in Europe and Australia but the aetiology has not been established. There are similarities between spotty liver disease and avian vibrionic hepatitis, a condition which was reported in the 1950s. A Vibrio-like organism was suspected to be the cause of avian vibrionic hepatitis, although this organism was never fully characterised. We report the isolation of a novel Campylobacter from five separate outbreaks of spotty liver disease. The conditions required for culture, the growth characteristics, electron microscopical morphology and results of the phenotypic tests used in the identification of this novel Campylobacter sp. are described. The novel Campylobacter is slow growing and fastidious and does not grow on media routinely used for isolating Campylobacter sp. The morphology is typical for a Campylobacter sp. and phenotypic tests and a duplex real time PCR test differentiate the novel Campylobacter from other members of the genus. 16S rRNA analysis of 19 isolates showed an identical sequence which appears to represent a hitherto unknown sub lineage within the genus Campylobacter. Experimental intraperitoneal infection of four week old SPF chickens produced microscopic liver pathology indistinguishable from natural disease and the novel Campylobacter was recovered from the experimentally infected chicks. The isolates described appear to be a possible causal organism for spotty liver disease.

Mycobacterial disease in a population of 339 cats in Great Britain: II. Histopathology of 225 cases, and treatment and outcome of 184 cases.

This study investigated 339 cases of feline mycobacterial infection, with histopathology findings from 225 cases, and treatment and outcome information from 184 cases. Tissue samples from cats with cutaneous lesions or suspicious masses at exploratory laparotomy were submitted to the Veterinary Laboratories Agency for mycobacterial culture over a 4-year period to December 2008. The study reviewed the files for information about histopathology, treatment and outcome, and blindly reviewed histopathological changes (including staining for acid-fast bacteria [AFB]) in a sub-set of 45 cases. When a cat is suspected of having a mycobacterial infection, accurate identification of the species involved helps to determine possible treatment options and prognosis. The study confirmed that histopathology and the presence of AFB are useful tools in the recognition of mycobacterial infection. Unfortunately, they did little to help determine the species of mycobacteria involved. The study identified a group of cats that were negative for AFB at the primary laboratory, but from which mycobacteria could be cultured; commonly Mycobacterium bovis or Mycobacterium microti. The study also identified a group of cats which where culture negative, despite typical signs of mycobacterial infection and positive AFB staining. Many cases responded favourably to treatment (56% of the cases where information was available), and many cats gained complete remission (42%). However, relapses were common (64%) and often followed by pulmonary and/or systemic spread that may have resulted from treatment with short courses of single drugs. This study shows that the diagnosis and treatment of feline mycobacteriosis is complex and challenging.