COBISS: 1.08 Agris category code: L70, L73
DETECTION OF Salmonella Indiana IN BROILER PRODUCTION IN THE CZECH REPUBLIC
Irena SVOBODOVÂ 1
ABSTRACT
Salmonella has been linked to many foodborne diseases across the world. Several control measures have been implemented to reduce Salmonella in poultry farms. The present study was focused on presence and serotyping of Salmonella in various samples from broilers. Salmonella isolates were obtained by standard cultivation methods. Four samples of faeces (n = 8) and twenty pooled samples of neck skins (n = 40) were found as positive. Pooled samples of chicken breast fillet (n = 20) were negative. Positive detection of Salmonella in the neck skins may be caused by contamination from the digestive tract or from the environment of the slaughter line. An interesting finding is that in all serotyped isolates (n = 24) only Salmonella indiana was present. Because S. indiana may pose a risk to human health, preventive measures have to be performed during the whole production chain.
Key words: poultry / broilers / microbiology / Salmonella Indiana / serotyping/ Czech Republic
1 INTRODUCTION
Salmonella has been linked to many foodborne illnesses across the whole world, and it is still considered to be one of the main agents causing human gastroenteritis. Poultry carcasses, poultry meat and poultry products belong to the most frequently discussed source of Salmonella. Contamination of poultry products can occur through the whole production chain, but until now most studies have been focused on the primary production (Rasschaert et al., 2007). Several control measures have been implemented to reduce Salmonella contamination of poultry flocks at farm level as well as strict hygienic rules during poultry processing.
Salmonella spp. are pathogens but can frequently persist in animals as a transient member of the intestinal microbial population without causing disease; however, when host animals and their carried serotypes are consumed by humans, foodborne illness can result (Cal-laway et al., 2008). Serotyping of Salmonella isolates is a useful classification method that could provide a link be-
tween the patient and the source of infection. In the EU, S. enteritidis and S. typhimurium are the most frequent serovars associated with human illness. Human S. enteritidis cases are mostly associated with the consumption of contaminated eggs and poultry meat, while S. typhimu-rium cases with the consumption of contaminated pork, poultry and beef meat. The most frequently reported serovars in poultry are S. enteritidis, S. typhimurium, S. hadar, S. infantis, S. virchow (EFSA, ECDC, 2012).
Under the European Regulation (EC 2160/2003) a special international program for reducing Salmonella in broilers is used from 2009 in the Czech Republic. The main aim of this program is to reduce Salmonella positive flocks (all Salmonella serotypes with public health significance and special monitoring of S. typhimurium and S. enteritidis) to less than 1%. Regulation 2160/2003 (EC 2160/2003) is focused on primary production of poultry and sets the rules for monitoring Salmonella directly at the farm during rearing period. The year 2010 was the second year of implementing the EU reduction target of <1% for S. enteritidis and S. typhimurium for broiler
1 Univ. of Veterinary and Pharmaceutical Sciences Brno, Fac. of Veterinary Hygiene and Ecology, Dept. of Meat Hygiene and Technology, Palackeho tr. 1-3, Brno, 61242, Czech Republic, e-mail: svobodovai@vfu.cz
I. svobodovA
flocks. The Salmonella spp. prevalence was reduced from 5.0% in 2009 to 4.1% in 2010 (EFSA, ECDC, 2012).
European Regulation (EC 1441/2007) lays down preventive measures to reduce Salmonella in the food chain. The Regulation prescribes rules for sampling and testing, and sets limits for the presence of Salmonella in specific food categories and in samples from food processing. The current requirement is that the poultry meat products placed on the market during their shelf-life have to be free of Salmonella. In addition, process hygiene criteria require absence of Salmonella in 25 g of a pooled sample of neck skins.
The main objectives of the present study were: 1) to investigate the presence of Salmonella spp. in samples of faeces and neck skins; 2) to determine the relationship between Salmonella isolates from neck skins and faeces.
2 MATERIAL AND METHODS
2.1	THE POULTRY PROCESSING PLANT, FLOCK
CHARACTERISTIC
The study was conducted in one large commercial poultry abattoir during autumn and winter 2011. The poultry slaughter process included unloading, manual hanging to the processing line, electrical stunning and killing. In a separated area, the carcasses were scalded at a temperature 54 ± 2 °C for 180 s and plucked. Mechanical evisceration, final washing and veterinary inspection were made separately in the next area. The plant used evaporative chilling for 70 min; the temperature in chilling tunnel was under 0 °C. Line speed was 8000-8500 birds per hour.
All broilers came from Czech farms with conventional production. The average rearing period was 36 days and the average weight was 2,1 kg. Growth-promoting antibiotics were not used during rearing period.
2.2	SAMPLES COLLECTION
In total the abattoir was visited eight times between October and December 2011. The sampling plan was based on European Regulation 1441/2007, Annex 1, Chapter 2.1. (EC 1441/2007). Neck skin samples were obtained from carcasses after chilling. Fifteen neck skins (each 25 g) were sampled once a week; a total of 120 neck skins were sampled. Samples were removed using separate sterile scissors and plastic bags for each neck skin. The carcasses were then removed from the processing line, put into sterile plastic bags and saved at the cold storage room at the abattoir. One pooled faeces sample
(approximate weight of 500 g) was taken directly from the transport crates. Faeces samples and neck skin samples came from the same flock with known Salmonella status. All tested flocks were declared to be Salmonella negative. Samples of neck skins and faeces were transported to the laboratory under cooled conditions and processed immediately.
Samples of chicken breast fillets were taken only from those carcasses that were found presumptively positive (due to the suspect Salmonella colonies isolated from pooled neck skin samples). These types of samples were obtained directly at the laboratory from the carcasses stored at the abattoir. A total of 60 chicken breast fillets were collected.
2.3 BACTERIOLOGICAL ANALYSIS
Three pieces of neck skins were pooled to obtain a sample of at least 25 g; (40 pooled samples were analysed). Three samples of chicken breast fillet were pooled to obtain a sample of at least 25 g; a total of 20 pooled samples were analysed. From 8 flocks 25 g of faeces were analysed separately. The presence of Salmonella spp. was determined according to modified ISO 6579:2003 standard method. As the selective agar media, XLT4 agar and Brilliant Green Agar were used, incubated at 37 °C for 24 h. Suspect colonies were subcultured onto Blood Agar, incubated at 37 °C for 24 h, and confirmed by agglutination with poly O antiserum. After confirmation, isolates were serotyped at the National Institute of Public Health, Brno, Czech Republic. All the media used for the determination of Salmonella spp. were purchased from Oxoid, United Kingdom.
3 RESULTS AND DISCUSSION
In total eight samples of faeces, forty pooled samples of neck skins and twenty pooled samples of chicken breast fillet were analysed.
The presence of Salmonella in broiler flocks has to be excluded three weeks before slaughter. The samples of faeces are collected at the farm and analysis results have to be provided in Food chain information. All investigated flocks of broilers declared Salmonella negative status. But in four samples of faeces (flock numbers 2, 3, 6, 7) Salmonella (serotyped as S. indiana) was found. Determination of Salmonella status few weeks before slaughter is questionable, because in the time span between sampling at farm and slaughter the birds a new infection can acquire e.g. during transport (Rasschaert et al., 2007). It is well known that Salmonella spp. is excreted intermit-
Table 1: Presence of Salmonella spp. in neck skin samples and samples of chicken breast fillets
Flock	No. of Salmonella-positive	samples/total no. (%)
	neck skins	chicken breast fillets
1	0/5 (0)	-/-
2	5/5 (100)	0/5 (0)
3	2/5 (40)	0/2 (0)
4	2/5 (40)	0/2 (0)
5	1/5 (20)	0/1 (0)
6	5/5 (100)	0/5 (0)
7	5/5 (100)	0/5 (0)
8	0/5 (0)	-/-
Total	20/40 (50)	0/20 (0)
tently, so stress during transport can lead to presence of Salmonella spp. in faeces. Another cause of a positive finding of Salmonella in faeces can be inadequate cleaning of transport crates.
The results of microbiological analyses of neck skins and chicken breast fillets are shown in Table 1. Skin samples were contaminated by Salmonella in six of eight tested flocks (75%). In three cases, all five pooled samples were contaminated. In the same flock, there was found Salmonella in faeces, too. On the other hand, all samples of chicken breast fillets were found to be negative. Twenty isolates of Salmonella were obtained from neck skin samples. All these isolates were serotyped as S. indiana. This serovar was found both in faeces and pooled neck skin samples.
Positive detection of Salmonella in the neck skins may be caused by contamination from the digestive tract or from the environment of the slaughter line. The fact that Salmonella was not found in any of the tested meat samples, although samples of neck skins were positive proves that the correct handling and hygienic rules significantly reduces the risk of Salmonella infection of the final consumer.
An interesting finding is the presence of only one serotype of Salmonella in all samples. Salmonella indiana is an infrequently occurring serotype, isolated mostly from poultry, which has occasionally been the etiological agent of human gastroenteritis (Beckers et al., 1985). The worldwide frequency of the isolation of S. indiana is low. (Luque et al., 2009).
4	CONCLUSION
Cross-contamination of carcasses during processing cannot be avoided. Strict separation of flocks with Salmonella positive and Salmonella negative status have to be kept together with effective cleaning and disinfection of processing line. The occurrence of S. indiana poses a sporadic threat to human health. Education of consumer, proper food handling, complete cooking and other security measures greatly reduce possible foodborne disease.
5	ACKNOWLEDGEMENTS
Study was supported by the project MSM621571240.
6 REFERENCES
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