Prevalence and Genotyping of Campylobacter jejuni and Campylobacter coli from Ovine Carcasses in New Zealand

A pilot survey was performed to determine the prevalence of Campylobacter jejuni and Campylobacter coli on three age classes (lamb, hogget, and mutton) of ovine carcass trim postdressing and prechill. Sampling of hogget carcasses was undertaken 6 months before sampling of lamb and mutton carcasses. A total of 120 trim samples were collected from 11 processing plants across New Zealand. All samples were enriched and screened using PCR for the presence of C. jejuni and C. coli, and isolation was attempted for all screen-positive samples. Enumeration of Campylobacter from lamb trim samples showed that Campylobacter bacteria were present in very low numbers (<10 CFU/g). The overall prevalence of Campylobacter for ovine trim based on PCR detection was 33% (39 of 120 samples), with prevalences for hogget, lamb, and mutton carcass trim of 56% (28 of 50), 11% (4 of 35), and 20% (7 of 35), respectively. Whole genome sequencing was performed on a selection of C. jejuni and C. coli isolates, and the data were used to subtype using multilocus sequence typing (MLST) and whole genome MLST. Twenty-five MLST sequence types (STs) were identified among 44 isolates, including ST42, ST50, ST3222, and ST3072, which have been previously reported to be associated with ruminant sources. Four novel STs were also identified. Whole genome MLST analysis further discriminated isolates within a single ST type and demonstrated a genetic diversity among the ovine isolates collected. Genes associated with the oxacillinase class of beta-lactamase enzymes were identified in 41 of 44 Campylobacter isolates. This study provides preliminary data that can be incorporated into existing source attribution models to assist in determining the potential contribution of ovine sources to the burden of campylobacteriosis in New Zealand. HIGHLIGHTS Campylobacter prevalence for ovine carcass trim based on PCR detection was 33%. Enumeration of Campylobacter bacteria was <10 CFU/g on lamb trim. Twenty-five multilocus sequence types (STs) were identified among 44 isolates. Whole genome sequence analysis discriminated isolates within a single ST.

Automated summary

A pilot survey in New Zealand showed that the prevalence of Campylobacter in ovine carcass trim was 33% based on PCR detection, with hogget carcasses having the highest prevalence at 56%. Twenty-five MLST sequence types were identified among isolates, indicating genetic diversity among ovine isolates collected. Whole genome sequencing analysis discriminated isolates within a single sequence type.