Browsing by Author "Mulqueen K"

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Longitudinal survey investigating vectors and reservoirs for Campylobacter colonization of chickens on a New Zealand broiler poultry farm
(American Society for Microbiology, 2025-09-17) Kingsbury JM; French N; Midwinter A; Lucas R; Callander M; Hird CP; Smith S; Mulqueen K; Biggs R; Biggs PJ; Ercolini D
This longitudinal survey followed the life cycle of a New Zealand broiler flock to investigate sources of flock colonization by Campylobacter. Samples were collected at frequent intervals from potential Campylobacter reservoirs and sources, transmission routes for Campylobacter ingress into the broiler shed, and to monitor flock colonization. Of the 738 samples, 200 (27%) tested positive for Campylobacter. Campylobacter species from sample isolates included 316 Campylobacter jejuni, 39 Campylobacter coli, and 8 Campylobacter lari isolates; only C. jejuni was isolated from chickens. C. jejuni isolates (n = 199) were sequenced and consisted of seven sequence types (STs); the most abundant was ST6964 (105 isolates). Most flock isolates were ST6964 (44 isolates) or ST50 (27 isolates). ST6964 isolates closely matched those from the previous flock and another age-matched flock on the same farm, supporting a role for an on-farm reservoir contaminating flocks. There were six STs from catching crew and equipment isolates; the most prevalent were ST6964 (19 isolates) and ST50 (21 isolates). The close genetic match, high Campylobacter prevalence in catching samples (59/130, 45%), and the timing of flock colonization occurring closely following catcher presence in the shed support that catchers and equipment might also contaminate the shed and flock from prior flocks that they visited. There was no evidence for wildlife, feed, drinking water, breeder flock, or shed litter as sources of the Campylobacter genotypes colonizing the flock. Taken together, this study identified key areas where the poultry industry might focus on-farm risk management practices to reduce colonization of broiler flocks by Campylobacter.IMPORTANCECampylobacteriosis is the most frequently notified enteric disease in New Zealand, and New Zealand has one of the highest rates of campylobacteriosis among industrialized countries. Reducing Campylobacter colonization of poultry at the farm level would reduce reliance on processing interventions for reducing Campylobacter contamination of broiler meat. This study aimed to identify on-farm sources of Campylobacter contamination in New Zealand broiler chicken flocks. No evidence was found that wildlife, chicken feed, drinking water, or parent breeder flocks were contaminating sources. Instead, carryover of Campylobacter from the previous flock or other farm flocks, and/or contamination from chicken catching crews and their equipment, may have contributed Campylobacter strains that colonized the study flock. These are key areas where the poultry industry might focus on-farm risk management practices to reduce colonization of broiler flocks by Campylobacter.
Temporal reconstruction of a Salmonella Enteritidis ST11 outbreak in New Zealand
(Microbiology Society, 2025-10-30) Strydom H; Wright J; Bromhead C; Welch D; Williams E; Mulqueen K; de Ligt J; Biggs PJ; Paine S; Jefferies S; French N
Outbreaks caused by Salmonella Enteritidis are commonly linked to eggs and poultry meat internationally, but this serovar had never been detected in Aotearoa New Zealand (NZ) poultry prior to 2021. Locally designated genomic cluster Salmonella Enteritidis_2019_C_01, was implicated in a 2019 outbreak associated with a restaurant in Auckland. Four Enteritidis_2019_C_01 sub-clusters have since been identified, two retrospectively, in the Auckland region. Authorities initiated a formal outbreak investigation after genomically indistinguishable S. Enteritidis was isolated from the NZ poultry production environment. This study analysed 231 S. Enteritidis genomes obtained from the outbreak using Bayesian phylodynamic tools to gain insight into the outbreak's dynamics and origin. We used Bayesian integrated coalescent epoch plots to estimate the change of the Enteritidis ST11 population size over time and marginal structured coalescent approximation to estimate transmission between poultry producers. We investigated human and poultry isolates to elucidate the time and location of the most recent common ancestor of the outbreak and transmission pathways. The median most recent common ancestor was estimated to be February 2019. We found evidence of amplification and spread of strain Enteritidis_2019_C_01 within the poultry industry, as well as transmission events throughout the production chain. The intervention by the public health and food safety authorities coincided with a drop in the effective population size of the S. Enteritidis ST11 as well as notified human cases. This information is crucial for understanding and preventing the transmission of S. Enteritidis in NZ poultry to ensure poultry meat and eggs are safe for consumption.
The impact of primary and secondary processing steps on Campylobacter concentrations on chicken carcasses and portions
(Elsevier Ltd, 2023-04) Kingsbury JM; Horn B; Armstrong B; Midwinter A; Biggs P; Callander M; Mulqueen K; Brooks M; van der Logt P; Biggs R
Campylobacteriosis is the most commonly notified foodborne disease in New Zealand and poultry meat is the major source for human infection. Carcasses and portions were sampled from key points along primary and secondary processing chains of three New Zealand poultry processors to determine the impact of processing steps on Campylobacter concentrations. Primary processing reduced Campylobacter concentrations on carcasses by almost 6-log; the biggest reduction was achieved by the spinchill, followed by the scald step. Significant plant differences in the degree of Campylobacter reduction were also observed at these steps. The spinchill and final acidified sodium chlorite wash resulted in carcasses with low-to-no levels of Campylobacter regardless of concentrations at prior steps. A similar study was conducted at primary processing for one plant in 2013; significant improvements in Campylobacter mitigation since 2013 were noted. Campylobacter concentrations from final product from secondary processing were higher than concentrations at the end of primary processing. Drumsticks had lower Campylobacter concentrations than other portion types. Skin removal from product did not consistently result in product with lower Campylobacter concentrations. Results identify key areas to target for further reduction of Campylobacter on poultry meat, and provide a benchmark to compare the efficacy of future interventions.