Thermotolerant Campylobacter spp. – Report on monitoring studies performed in 2004–2005 in Poland

Abstract Numerous epidemiological data confirm the gravity of the food-born infections caused by thermotolerant Campylobacter spp. In Poland in 2004–2005 a monitoring study was carried out to detect the presence of thermotolerant Campylobacter spp. in poultry carcasses. In 2004, 385 and in 2005, 240 poultry carcasses were tested. Monitoring tests showed that in 2004 as much as 74% of poultry carcasses were infected with Campylobacter spp. The results of 2005 monitoring tests were very close to those in the previous year and 75.4% of all tested samples were infected.


Introduction
In recent years in most European countries a clear rise in the number of food-born infections caused by thermotolerant Campylobacter spp. mainly C. jejuni and C. coli was observed (Atterbury, Connerton, Dodd, Rees, & Connerton, 2003;Moore et al., 2005;Patrick et al., 2004). This trend is confirmed by the most recent data collected in 25 EU Member States. The above test data shows that the number of human campylobacterioses in 2004 reached the level of 183,961, and the total campylobacteriosis incidence rate was 47.6 per 100,000 people. Additionally, it should be noted that there are clear differences between EU Member States, since in the Czech Republic the campylobacteriosis incidence rate was 249.6 per 100,000 people, whereas in Poland, France and Greece the incidence rate was from 0.1 to 3.6 (EFSA, 2006 million Campylobacter spp. incidents recorded in human population (Bhaduri & Cottrell, 2004;Zhao et al., 2001).
Campylobacteriosis in humans is caused by the consumption of food live C. jejuni cells, and the disease symptoms may be caused already by 500 cells of microorganism (Bhaduri & Cottrell, 2004;Daczkowska-Kozon, 2002;FSAI, 2002).
The current data coming from various European countries show quite a varied level of poultry carcasses contamination with thermotolerant Campylobacter spp. The tests performed in 2004 in 25 EU Member States showed that Campylobacter spp. were present in 2.2-62.2% of fresh poultry meat (EFSA, 2006).
The results of tests carried out in the United States showed that in 70.7% of samples of tested raw meat the presence of Campylobacter spp. was detected (Zhao et al., 2001). Meanwhile a much lower contamination level of poultry carcasses was found out in the tests carried out in South Africa. The above data shows that 32% of tested fresh and frozen poultry carcasses is contaminated with thermotolerant Campylobacter spp. (van Nierop et al., 2005).
The second major hazard may be a result of improper hygienic habits and disregard of good manufacturing practice (GMP) principles. This is related to the transfer of bacteria from raw meat to other foodstuffs that are not subject to further heat treatment (cross-contamination) (Atanassova & Ring, 1999;Atterbury et al., 2003;Luber et al., 2006).
In Poland prior to 2003 there was no epidemiological data about the number of intestinal diseases caused by Campylobacter spp. This situation changed pursuant to the issue of the Ordinance of the Minister of Agriculture and Rural Development on 27 August 2003 ''On the specification of zoonoses, their monitoring and operational procedures in case of disease outbreak or detection of biological pathogens'' and campylobacterioses have to be registered mandatorily.
Number of registered campylobacterioses in 2003 amounted to 15, whereas in 2004, it amounted to 24. In 2004 the peak number of campylobacterioses was recorded in the third quarter of the year (Czarkowski, Cielebąk, Stępień , & Kondej, 2005). The seasonality of campylobacterioses in humans was also observed in Denmark, England and Wales. In these countries a significant increase of infections was also recorded in June, July and August (Louis et al., 2005;Patrick et al., 2004).

Materials and methods
In 2004-2005 in Poland in selected provinces monitoring tests were carried out to detect the presence of Campylobacter spp. in poultry carcasses.
The tests were carried out by the laboratories of Provincial Sanitary and Epidemiological Stations, pursuant to the procedure described in the standard PN ISO 10 272: 2002 ''Food and feed microbiology. Horizontal method for detection of thermotolerant Campylobacter spp.''. For testing purposes two 25 g samples were taken from poultry carcasses, from the skin near the neck and breast muscle.
The detection of Campylobacter presence in one or both samples from the carcasses was evaluated as a positive result testifying carcass infection. Failure to detect Campylobacter in any of the two samples taken from a certain carcass was a proof of negative result that is the lack of contamination.

Statistical calculations
Confidence semi-interval was calculated for the determination of bacteria present in the population of poultry carcasses in Poland, using the formula for fraction standard error where n is the total number of all samples tested and p and q are the fractions of contaminated and non-contaminated samples.
The confidence semi-interval is l SE p i.e. l ffiffiffi ffi pq n p where l read out of t distribution tables for large populations amounts to 1.96 with confidence interval (a À 1) = 0.95.

Discussion of results
In 2004 the monitoring tests covered the total number of 385 poultry carcasses. In provinces where monitoring tests were carried out the number of contaminated carcasses ranged from 20% to 93% (Table 1) (EFSA, 2006).
In Europe slightly lower Campylobacter contamination rates of broiler flocks is observed in Nordic countries such as Sweden and Finland, partly as a result of cold climate, but also due to stringent biosecurity programmes and good manufacturing practice (GMP).
Over the past 3 years, Denmark, Norway and Sweden have all experienced a decrease in the number of Campylobacter positive broiler flocks. This may, in part, be explained by the implemented monitoring programmes and effective control strategies in food animals, especially broiler chickens. Monitoring programmes for Campylobacter in broilers have been implemented in Austria, Denmark, Finland, Italy (Veneto region), Norway, The Netherlands and Sweden. The programmes share common traits and generally focus on a high level of biosecurity at the farm level to prevent flocks from being infected and logistic slaughter i.e. slaughtering positive flocks at the end of the day to prevent cross-contamination at the slaughterhouse (EFSA, 2006).
In Estonia effective quality-control programme in large-scale poultry processing plant accounted for the lower contamination levels of fresh chicken meat compared to contamination level with the same type of products of small-scale plant. Of the raw chicken products of Estonian origin, 15.8% were positive for Campylobacter. The prevalence of Campylobacter in the products of the small-scale poultry meat plant (35.6%) was significantly higher than in those originated from the large-scale company (6.3%) (P < 0.001) (Roasto, Praakle, Korkeala, Elias, & Hänninen, 2005).
Therefore, it is legitimate to continue monitoring the contamination rate of poultry carcasses with Campylobacter bacteria. However, it is not necessary to eliminate the contaminated poultry carcasses from the market. However, special attention has to be paid to educate the society about the ways of Campylobacter infection spreading (consumption of raw or undercooked meat and improper hygienic habits).