University of Limerick
Dillon_2010_surveillance.pdf (70.31 MB)

Surveillance and cross contamination of salmonella spp., in pork, with profiles of nalidixic acid resistance in salmonella

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posted on 2022-09-22, 10:15 authored by Colm Dillon
Salmonella is a major foodborne pathogen and porcine products are an important source. With this in mind, pork sausages were surveyed for Salmonella prevalence. Sausages were sampled during August-December 2008, none of which were positive for Salmonella. As an alternative porcine source of salmonella, 102 pig ear pet treats were surveyed from October 2008 to September 2009. Salmonella was detected in 24.5% of treats using a culture detection method and 28.4% using peR. As dogs are the main consumers of pig ear treats, a veterinary surveillance study was undertaken. Salmonella was not detected in any of 86 rectal swabs from dogs attending 2 different veterinary clinics between February and April and August and October 2009. Emergence of antimicrobial resistance is a significant health problem. Nalidixic Acid resistance is seen as a marker for the emergence of Fluoroquinolone resistance, the antimicrobials of choice for treating salmonella infections. Nalidixic Acid intermediate (4 isolates) and resistant (5 isolates) isolates were examined for mutations in the Quinolone Resistance Determining Region (QRDR) of gyrA and pare. Single mutations at Serine-83 and Aspaltic Acid-87 in the QRDR of gyrA were observed for all Nalidixic Acid resistant isolates. One intermediate isolate contained a mutation in parC, Threonine-57 to Serine. In the presence of an efflux pump inhibitor, susceptibility to Fluoroquinolones increased in all isolates. The presence of plasmid-mediated quinolone resistance was investigated but was not detected in salmonella in this study. Salmonella infection is most often the outcome of poor personal hygiene and cross contamination in domestic kitchens. A hygiene study looked at cross contamination during the preparation of a contaminated pork meal. Five rinsing regimes were examined to see which was most effective in reducing salmonella cross contamination. The addition of a 50% bleach spray to hot water and detergent proved to be the most effective cleaning regime. Salmonella remains an important threat to human health and this threat is ever increasing with the emergence of antimicrobial resistance. Members of the general public need to be aware of the risks associated with handling and preparing animal oliginated products. Good hygiene practices need to be followed.



  • Master (Research)

First supervisor

Adley, Catherine C.





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