Evaluation of cleaning and disinfection procedures against Samonella enterica at swine farms, transport and lairage facilities

Evaluation of the cleaning and disinfection protocols effectiveness against Salmonella in three points of the pork production chain: finishing farm, transport and lairage. A 22.2% of the farms, 62.5% of the slaughter trucks and 63.6% of the holding pens tested were positive to Salmonella after cleaning and disinfection procedures. The other samples collected in trucks and lairage shows that there is also contamination before the pigs staying. These results show that the protocols carried out at the farms, trucks and abattoirs included in this survey are not efficient to eliminate Salmonella. Introduction Salmonella enterica is one of the most common and widely distributed food-borne pathogens. The bacteria can contaminate almost any food type although raw eggs, poultry and pork are the most common sources of human outbreaks of salmonellosis [1]. Contamination can occur at any point of the food chain including primary production. Due to the ability of Salmonella to survive during large periods of time in the environment, particularly in the presence of organic matter, cleaning protocols are of outstanding importance. This investigation aimed to assert the efficacy of routinely cleaning and disinfection procedures performed at three points of the pork production chain: finishing farms, transport and lairage. Material and Methods a) Study design Finishing farms: Thirty-six pig finishing farms performing a strict all-in/all-out management (AI/AO) were evaluated. Within each farm, twelve samples were collected from pen floors (5 samples), pen walls (5 samples), corridors (1 sample) and dust (1 sample) after cleaning and disinfection procedures, just before the entrance of a new batch of animals. Transport: Eight slaughter trucks were evaluated in three sampling rounds: (1) before loading the animals at the farm (preload), (2) after unloading the pigs at the abattoir (postload) and (3) after cleaning and disinfection procedures. Each truck included three storeys and therefore three samples, one per floor, were collected in each sampling round. In total, nine samples were recovered from each monitored slaughter truck. Surface samples were collected at preload and after cleaning and disinfection procedures, while floor faeces were collected at postload. Holding pens: Sixty-six holding pens in two different abattoirs were evaluated in four sampling rounds: (1) before the entry of the pigs, (2) at half of the working day, (3) at the end of the working day and (4) after cleaning procedures. Surface samples were collected in sampling rounds 1 and 3 while faecal samples were collected in the other two sampling rounds (2 and 3) during the staying of pigs. b) Sample collection Surface samples were collected using gauzes previously moistened in peptone buffered water (PBW). Each sample was obtained by swabbing five points of 25cm x 25cm. Floor faecal samples were constituted by five fresh fecal pinches collected at five different locations of the pen or lorry. c) Isolation methodology Bacteriological analyses were made according to EN-ISO 6579:2002/Amd 1:2007. Gauzes immersed in 50 ml of PBW or pool faeces were sent to the laboratory immediately after their collection in cooling conditions. One isolate of each positive sample was further serotyped by slide agglutination according to Kaufmann-White scheme using commercial antisera.