Prevalence and diversity of Arcobacter spp. in poultry meat in New Zealand : a thesis presented in the partial fulfillment of the requirements for the degree of Master of Science in Veterinary Microbiology and Public Health at Massey University, Palmerston North, New Zealand

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2006
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Massey University
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The microaerophilic bacterium Arcobacter has received increased attention in recent years as an emerging foodborne human pathogen. Although phenotypically related, arcobacters differ from campylobacters in their ability to grow aerobically and at lower temperatures. Poultry are considered a significant reservoir of this organism, with an isolation rate of up to 72% in faecal samples, and up to 100% in meat samples. To date, four species; A. butzleri, A. skirrowii, A. cryaerophilus, and A. cibarius have been isolated from poultry. The first three species have also been found to be associated with human and animal illnesses such as diarrhoea, bacteraemia, mastitis and abortions. The organisms are also found in raw meat products as well as in surface and ground water. Since most laboratories still do not use appropriate isolation techniques, the occurrence of this organism in food sources and their role in human illnesses is greatly underestimated. This is the first investigation of the prevalence of arcobacters in poultry meat in New Zealand. The aim of this study was to compare the most commonly used Arcobacter isolation methods. In addition, this study aimed to estimate the prevalence of Arcobacter spp. in retail poultry in New Zealand. Other aims include comparison of genetic diversity of Arcobacter spp. isolated from three different poultry producers, and by different methods, and estimation of overall genetic diversity of arcobacters present in New Zealand. During the period of May to October 2005, a total of 150 fresh, whole, retail poultry carcass produced by three different producers were purchased through two supermarket outlets in Palmerston North, New Zealand. Isolation of Arcobacter was done by seven different techniques. Arcobacter-like organisms were identified presumptively by phenotypic tests; temperature tolerance, aerotolerance, motility , and oxidase production. These presumptive arcobacters were confirmed by a species-specific multiplex PCR (m-PCR) either as A. butzleri, A. cryaerophilus or A. skirrowii. DNA sequencing was done for selected isolates from both species to further confirm the PCR results. The PCR positive isolates were subjected to Pulsed-Field Gel Electrophoresis (PFGE) following restriction digestion with Eagl. It was found that 55.3 % of 150 retail poultry sold in New Zealand were harbouring Arcobacter species. Two species; A. butzleri and A. cryaerophilus were detected by m-PCR which was later confirmed by sequencing. A total of 189 isolates were detected by six methods from 83 retail poultry samples. A. butzleri was the predominant species and was detected in 51.3% of the samples, whereas A. cryaerophilus was detected only in 8% of the samples. A. butzleri and A. cryaerophilus accounted for 92.6% (n=175) and 7.4% (n-14) of the isolates, respectively. A. butzleri was the only Arcobacter species present in 46.6% samples, and A. cryaerophilus only in 3.3% of the samples. Both species were detected simultaneously in 4.6% of the samples. There was a wide variation among the prevalence rate of Arcobacter spp. in retail poultry from different producers varying from 30 to 98%. There was also a wide variation among the isolation rates of different methods varying from 3.3 to 39.3%. The best isolation method was found to be Arcobacter-broth enrichment followed by passive filtration through a sterile filter of 0.45μm, onto blood-agar plates. No single isolation method detected all arcobacters. PFGE of Arcobacter isolates demonstrated the occurrence of multiple genotypes of both A. butzleri and A. cryaerophilus in the retail poultry from the same producers, and even in a single poultry. The possible explanations for the large amount of heterogeneity include multiple sources of contamination, the occurrence of multiple parent genotypes for both species in a single poultry carcass, and a high degree of genomic recombination among the progeny of historical parent genotypes. This study highlights the high prevalence of Arcobacter spp. in poultry meat in New Zealand. It also indicates prevalence of arcobacters in poultry carcass varies greatly with the choice of isolation method and none of the currently available methods are appropriate for the detection of all species of arcobacters in New Zealand. Therefore, two or more methods should be used in parallel. The level of contamination of poultry carcass may vary with the processing practices of a slaughterhouse. To eliminate or reduce arcobacters in retail poultry, maintenance of slaughter hygiene is of utmost importance. This may be achieved by regular microbiological monitoring of carcasses according to the HACCP principles. Further studies comparing the fingerprinting pattern of Arcobacter spp. isolates obtained from retails poultry with human isolates are necessary to test the hypothesis that poultry meal is an important source for Arcobacter infection in human.
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Poultry -- Microbiology, New Zealand, Poultry industry -- Health aspects
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