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Salmonella and Campylobacter in Poultry Discussed at PSA Meeting

27 August 2012, at 12:00am

Papers presented at the Poultry Science Association Annual Meeting in July 2012 reviewed current understanding of Salmonella and Campylobacter contamination of poultry carcasses and compared Salmonella prevalence rates of raw chicken in different countries.

Two papers were presented at a special symposium focusing on these two foodborne pathogens at the Poultry Science Association annual meeting in 2012.

Salmonella and Campylobacter in Poultry: Past, Present and Future

Four or five decades ago, one of the main concerns was to extend the shelf-life of refrigerated processed poultry, according to Dr Nelson A. Cox of the USDA ARS Russell Research Center in Athens, Georgia. Some Salmonella analyses were done but primarily indicator organisms were used. At that time, Campylobacter had not been recognized as a foodborne (poultry-borne) enteropathogen.

At present, both of these microorganisms are routinely tested for both by cultural and rapid, high-tech methods.

It is fairly well established as to how Salmonella gets into a broiler flock but many points of cultural methodology are not yet fully understood. Even for a relatively well-understood sample type such as a chilled poultry carcass, there is no internationally recognized standard method for Salmonella detection; for sample size, laboratory methods, number of colonies to pick etc. For example, Salmonella prevalence rates on chicken carcasses can be increased or decreased depending on the sampling methods used, such as changing the portion cultured after whole carcass rinsing or changing the sample weight in neck skin. Also many studies have demonstrated that cultural techniques can influence the serotypes that are recovered from samples and certainly that along with binomial and multinomial probabilities of picking serotypes at various ratios within a medium may explain the changing serotype patterns reported during rearing and processing of poultry.

Therefore, along with a better understanding of the weaknesses of our lab methods, internationally agreed upon and reliable culture methods for both Salmonella and Campylobacter in poultry from the farm to retail are sorely needed, according to Dr Cox.

The situation is more complex with Campylobacter because it is more difficult to develop reliable culture methods, particularly from dry samples because this microorganism rapidly converts to a non-cultural state. Plus there is still a great deal of controversy as to exactly how Campylobacter gets into the commercial poultry flocks.

For a young poultry research scientist, the future is very bright, concluded Dr Cox. Much more research is needed on both of these organisms in many different areas.

Epidemiology of Salmonella on Raw Poultry at the Retail Level: an International Perspective

Poultry meat continues to be a significant source for human salmonellosis worldwide. Retail establishments serve as an end point sale for raw and processed poultry products.

Presenting a paper prepared by co-authors from eight leading international institutions, W.Q. Alali of the University of Georgia explained that food safety surveillance systems for raw poultry have been carried out mainly at the processing plants. That being said, it is important to monitor the status of pathogens, e.g. Salmonella, on raw poultry at the retail level.

There are many factors, e.g. temperature abuse, cross-contamination, that could affect the prevalence and population of Salmonella at retail. While data on Salmonella on raw poultry is available in several developed countries such as US-National Antimicrobial Resistance Monitoring System (NARMS), such information is not available in many developing countries, which limits the ability for international organizations such as WHO and FAO to perform risk assessments that are representative for poultry production worldwide.

Due to lack of internationally agreed standards on acceptable Salmonella levels in raw poultry and methods of testing poultry products for the presence of Salmonella, various countries are formulating policies that lack a scientific basis.

This group of researchers conducted studies in China, Colombia, Russia and Viet Nam to determine the prevalence, loads, serotypes and antibiotic susceptibility of Salmonella on raw poultry at retail level.

Overall Salmonella prevalence on broiler chicken in China, Colombia, Russia and Viet Nam were 52.2 per cent (n=1,152), 26.7 per cent (n=1,003), 31.5 per cent (n=698) and 45.9 per cent (n=1,000), respectively.

In general, Salmonella prevalence was not significantly associated with one retail market type. Frozen chicken had lower Salmonella prevalence than chilled in China and Colombia but not in Viet Nam and Russia.

The average concentration of Salmonella found was 1.7 and 2.75 logMPN per carcass in China and Colombia, respectively. Most common serotypes were Enteritidis, Indiana and Typhimurium in China; whereas Paratyphi B, Enteritidis and Heidelberg were most common in Colombia. Moderate-to-high levels of multi-drug resistant Salmonella were detected in both countries.

Authors of this paper were W.Q. Alali, B. Yang and J. Meng (Northwest A&F University, China), P. Donado (Colombian Corporation of Agricultural Research, Biotechnology and Bioindustry Center), I. Walls (USDA, National Institution of Food and Agriculture), R. Gaydashov (Consumer Rights Protection Society, Moscow, Russia) T. Yen (National Institute for Food Control, Hanoi, Viet Nam), D.L.F. Wong (World Health Organization, Geneva, Switzerland) and M.P. Doyle (University of Georgia).

August 2012