Genomic adaptations of Campylobacter jejuni to long-term human colonization

Background Campylobacter is a genus of bacteria that has been isolated from the gastrointestinal tract of humans and animals, and the environments they inhabit around the world. Campylobacter adapt to new environments by changes in their gene content and expression, but little is known about how they adapt to long-term human colonization. In this study, the genomes of 31 isolates from a New Zealand patient and 22 isolates from a United Kingdom patient belonging to Campylobacter jejuni sequence type 45 (ST45) were compared with 209 ST45 genomes from other sources to identify the mechanisms by which Campylobacter adapts to long-term human colonization. In addition, the New Zealand patient had their microbiota investigated using 16S rRNA metabarcoding, and their level of inflammation and immunosuppression analyzed using biochemical tests, to determine how Campylobacter adapts to a changing gastrointestinal tract. Results There was some evidence that long-term colonization led to genome degradation, but more evidence that Campylobacter adapted through the accumulation of non-synonymous single nucleotide polymorphisms (SNPs) and frameshifts in genes involved in cell motility, signal transduction and the major outer membrane protein (MOMP). The New Zealand patient also displayed considerable variation in their microbiome, inflammation and immunosuppression over five months, and the Campylobacter collected from this patient could be divided into two subpopulations, the proportion of which correlated with the amount of gastrointestinal inflammation. Conclusions This study demonstrates how genomics, phylogenetics, 16S rRNA metabarcoding and biochemical markers can provide insight into how Campylobacter adapts to changing environments within human hosts. This study also demonstrates that long-term human colonization selects for changes in Campylobacter genes involved in cell motility, signal transduction and the MOMP; and that genetically distinct subpopulations of Campylobacter evolve to adapt to the changing gastrointestinal environment

A serological survey of leptospiral antibodies in dogs in New Zealand

AIM: To investigate the prevalence of titres to four endemic leptospiral serovars in dog sera from the lower half of the North Island, and the South Island of New Zealand submitted to diagnostic laboratories, and to explore the association between the prevalence of seropositive samples to leptospirosis and breed group, age group and sex. METHODS: Serum samples from 655 dogs residing in the central and lower North Island and from the South Island of New Zealand were sourced from the Massey University Veterinary Teaching Hospital and from submissions to New Zealand Veterinary Pathology in 2005. They were screened by the Microscopic Agglutination Test (MAT) against Leptospira interrogans serovars Copenhageni and Pomona and L. borgpetersenii serovars Hardjo and Ballum. Titres greater or equal to 96 were considered positive. Variables investigated for their association with the prevalence of seropositive samples to leptospirosis included serovar, breed, North vs. South Island, age and sex. RESULTS: Positive MAT titres to Leptospira interrogans serovar Copenhageni were found in 10.3 % of dogs (95% CI=8.1-12.9), and were more common than positive titres to other leptospiral serovars. Small breeds did not have a lower prevalence of Copenhageni titres than other breeds. Positive titres to Leptospira borgpetersenii serovar Hardjo were associated with breeds of dogs used as farm working dogs. There was no significant difference in the prevalence of positive leptospiral titres between dogs from the North or South Islands. Dogs greater than 12 years of age were less likely to have positive titres to Leptospira than younger dogs. No association was found between positive titres and sex. CONCLUSIONS: Breeds of dogs used as farm working were at greater risk of exposure to Leptospira borgpetersenii serovar Hardjo. Small breeds did not have a lower risk of seropositivity to Copenhageni than farm working breeds. Further study should be undertaken to confirm the prevalence of positive titres to leptospirosis in farm dogs and dogs resident in the South Island. CLINICAL RELEVANCE: The risk of dogs being exposed to Leptospira interrogans serovar Copenhageni, and requirement for vaccination against serovar Copenhageni, cannot be determined by geographical location or breed group. Vaccination against Leptospira borgpetersenii serovar Hardjo is likely to be beneficial in working dogs

Investigation of mortalities associated with Salmonella spp. infection in wildlife on Tiritiri Matangi Island in the Hauraki Gulf of New Zealand

CASE HISTORY: Salmonellosis was suspected as the cause of death in eight wild animals on Tiritiri Matangi Island, in the Hauraki Gulf of New Zealand, between November and September 2011, including three hihi (Notiomystis cincta), a tuatara (Sphenodon punctatus), a masked lapwing (Vanellus miles novaehollandiae), and a saddleback (Philesturnus carunculatus). An outbreak investigation to identify the source and distribution of infection was undertaken over the summer of 2011–2012. CLINICAL AND LABORATORY FINDINGS: Surveillance of five species of forest bird (n=165) in December 2011 returned a single positive result for Salmonella spp. Environmental sampling of 35 key water sources and hihi supplementary feeding stations conducted in December 2011 and March 2012 returned isolates of S. enterica subspecies houtenae and S. enterica serovar Saintpaul from a stream, a dam and a supplementary feeding station. The same serotypes were identified in tissue samples collected from post mortem specimens of the affected birds, and their similarity was confirmed by pulsed-field gel electrophoresis. DIAGNOSIS: Mortality in wildlife associated with infection with S. enterica subspecies houtenae and S. enterica serovar Saintpaul. CLINICAL RELEVANCE: This is the first detection of these Salmonella spp. from wild birds in New Zealand. Our study highlights how active surveillance in response to observed disease emergence (here mortalities) can provide important insight for risk assessment and management within populations of endangered species and inform risk assessment in translocation planning