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Aim
To assess the relative incidence of Salmonella sp. and Campylobacter sp. in poultry samples submitted to the Food Microbiology section at Government Analytical Services for January to August 2009, and to compare the incidence of campylobacter isolates relative to salmonella isolates.
Introduction
The genus Campylobacter, first discovered in 1963, describes Gram-negative, spiral, microaerophilic bacteria. Motile, with either uni- or bi-polar flagella, the organisms have a characteristic spiral/corkscrew appearance (see photo) and are oxidase-positive. Campylobacter jejuni is now recognized as one of the main causes of bacterial foodborne disease in many developed countries. At least a dozen species of Campylobacter have been implicated in human disease, with C. jejuni and C. coli the most common. C. fetus is a cause of spontaneous abortions in cattle and sheep, as well as an opportunistic pathogen in humans.
Campylobacteriosis, the illness caused by Campylobacter, is a zoonotic emerging infectious disease characterized by acute to chronic gastroenteritis (often bloody), abdominal pain, malaise, fever, nausea, and vomiting (Chin, 2000). The severity of the disease is variable, but usually people who get campylobacteriosis recover completely within 10 days. For a small number of people, Campylobacter infection may result in long-term health problems such as Reiter’s syndrome or a rare disease called Guillain-Barré syndrome that occurs several weeks after the acute diarrheal illness, and may result in permanent paralysis (Ang et al, 2001; van Doorn et al, 2008).
There are six (6) major routes of transmission which have been recognised for Campylobacter infections, these are food, water, the environment, direct contact with animals, pets, person to person.
Food is the most common vehicle for the spread of Campylobacter, and chicken is the most common food implicated; however, other foods such as unpasteurized milk, salad vegetables and shell fish have been recognised as agents of Campylobacter infections. Contamination of food can occur during animal slaughter and processing when the edible portions come into contact with animal feces, hence cross-contamination. Cross-contamination has also been recognised as a major vehicle for transmission of Campylobacter jejuni infections in homes and food businesses.
Ingestion of as few as 500 organisms; an amount that can be found in one drop of chicken juice – has been proven to cause human illness (FSIS, 1996; Tauxe et al, 1992). Despite this low infectious dose and the prevalence of Campylobacter jejuni in the environment is difficult to determine as Campylobacters have the ability to enter a viable but non-culturable (VNBC) state. Most cases of Campylobacter infection occur as isolated, sporadic events, and are not usually a part of outbreaks.
Salmonella spp. are gram-negative, rod-shaped bacilli that can cause diarrheal illness in humans. The Salmonella family includes over 2,300 serotypes of bacteria. Two types, Salmonella enteritidis and Salmonella typhimurium are the most common and account for half of all human infections only surpassed by Campylobacter jejuni. Similar to Campylobacter poultry has been recognised as the major source of Salmonella infections, however the number of cases and outbreaks has been significantly reduced as comprehensive food safety programmes have been introduced to control salmonella contamination.
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