Surface behaviour of S. Typhimurium, S. Derby, S. Brandenburg and S. Infantis Greetje A.A. Castelijn a,b , Jo-Ann Parabirsing b , Marcel H. Zwietering b , Roy Moezelaar a , Tjakko Abee a,b, * a Top Institute Food and Nutrition (TIFN), Nieuwe Kanaal 9A, 6709 PA Wageningen, The Netherlands b Laboratory of Food Microbiology, Wageningen University, Bomenweg 2, 6703 HD Wageningen, The Netherlands 1. Introduction Salmonella infections in humans are in general food borne, with an important source of risk being food from animal origin. The most frequently implicated food sources are eggs, poultry meat and pork (EFSA, 2011a,b). As shown by epidemiological studies in the European Union (EU), consumption of pork is associated with 15–20% of all human cases of salmonellosis and with 7.8% of all foodborne outbreaks (Botteldoorn et al., 2003; ECDC, 2011). Within the EU, the prevalence of Salmonella on slaughter pigs and in pork processing environments is well monitored. This reveals that at point of slaughter on average 10.3% of the slaughter pigs and after the slaughter process 8.3% of the carcasses are positive for Salmonella (EFSA, 2008). Salmonella serovars that are repeatedly found on farm animals within the pork processing environments and on carcasses at the end of the slaughter process are S. Typhimurium, S. Derby, S. Infantis and S. Brandenburg Veterinary Microbiology 161 (2013) 305–314 A R T I C L E I N F O Article history: Received 8 June 2012 Received in revised form 27 July 2012 Accepted 28 July 2012 Keywords: Salmonella Survival Biofilm Stainless steel Desiccation Peracetic acid A B S T R A C T Cross-contamination due to Salmonella on the surface of processing equipment greatly contributes to contamination of pork products. Therefore, a clear understanding of surface and survival behaviour of relevant Salmonella serovars in pork processing environments is needed to develop better strategies for Salmonella control. Within this study the biofilm forming behaviour of S. Typhimurium, S. Derby, S. Brandenburg and S. Infantis isolates was analysed using the crystal violet assay. This assay, commonly used to analyse total biofilm formation, revealed variation in biofilm forming capacity between and within serovars. This has not been shown before for S. Derby, S. Brandenburg and S. Infantis. From each serovar, isolates with different biofilm forming capacity were selected to analyse biofilm formation on stainless steel. This revealed no significant differences between biofilm formation on polystyrene compared to stainless steel. Furthermore a relation was observed between biofilm forming capacity of an isolate and survival on stainless steel surfaces. On such surfaces, biofilms showed greater and longer survival than planktonic cells, and they were less susceptible to peracetic acid disinfection treatments. However, the latter effect was marginal and only observed in the presence of organic material, which drastically decreased the activity of peracetic acid. With the obtained results a hierarchical cluster was also performed to identify differences and similarities between the four different serovars. This indicated that the surface behaviour of S. Typhimurium was more comparable to S. Infantis than to S. Derby or S. Brandenburg. ß 2012 Elsevier B.V. All rights reserved. * Corresponding author at: Laboratory of Food Microbiology, P.O. Box 8129, 6700 EV Wageningen, The Netherlands. Tel.: +31 317 484981; fax: +31 317 484978. E-mail address: tjakko.abee@wur.nl (T. Abee). Contents lists available at SciVerse ScienceDirect Veterinary Microbiology jo u rn al ho m epag e: ww w.els evier.c o m/lo cat e/vetmic 0378-1135/$ – see front matter ß 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.vetmic.2012.07.047