Microbial ecology of meat slicers as determined by denaturing gradient gel electrophoresis Alexandria W. Mertz a, b , Ok Kyung Koo a, b, 1 , Corliss A. O’Bryan a, b , Rubén Morawicki b , Sujata A. Sirsat c , Jack A. Neal c , Philip G. Crandall a, b , Steven C. Ricke a, b, * a Center for Food Safety, University of Arkansas, Fayetteville, AR, USA b Food Science Department, University of Arkansas, Fayetteville, AR, USA c Conrad N. Hilton College of Hotel and Restaurant Management, University of Houston, Houston, TX, USA article info Article history: Received 11 July 2013 Received in revised form 29 January 2014 Accepted 11 February 2014 Available online 22 February 2014 Keywords: Deli slicer Denaturing gradient gel electrophoresis Sanitation abstract Cross-contamination of pathogens and spoilage bacteria during slicing of ready to eat meats is an important factor that has been shown to impact both food quality and consumers’ safety. In this study we analyzed the microbial diversity and total microbiological ecology of different niches on 8 deli meat slicers using standard plate counts as well as culture-independent PCR-denaturing gradient gel elec- trophoresis (DGGE) analysis. Using aerobic plate counts it was determined that areas underneath the slicer and on the back plate had the highest total bacterial populations. There was slight similarity be- tween total aerobic plate counts by slicer and the number of bacterial genera/species determined by DGGE. The DGGE analysis demonstrated that members of the genus Pseudomonas were the most com- mon bacteria to be found on slicers. This may serve as an estimate of the effectiveness of current cleaning and sanitizing practices to remove biofilms, a possible role for competitive inhibition in preventing colonization by pathogens and an indication of the range and diversity of non-pathogens on these food contact surfaces. Ó 2014 Elsevier Ltd. All rights reserved. 1. Introduction Cross-contamination of ready-to-eat (RTE) food by foodborne pathogens is a major concern in food processing and preparation areas in the retail sector as well as in hospital and geriatric care facilities. The powered slicers used to slice meats, cheeses and vegetables are among the most difficult items to clean and are probably the most microbiologically hazardous pieces of equip- ment used in food preparation (Powitz, 2009). The time spent ensuring proper sanitation and maintenance by the user is time well spent in the prevention of vehicle-mediated foodborne illness. In the US the older population (65þ) numbered 41.4 million in 2011, an increase of 6.3 million or 18% since 2000 (Administration on Aging, 2013). Older adults tend to be more vulnerable to foodborne illness for a variety of reasons including an age related decrease in the immune system, daily medications that can inhibit immune systems, health compromised by a chronic disease, and a decline of smell and taste sensors that may not alert them to spoiled foods (Buzby, 2002; Gavazzi & Krause, 2002; Smith, 1998). An estimated 3.3 million Americans will live in the nation’s nearly 16,000 nursing homes during 2013 (Comarow, 2013), and an additional 735,000 people nationwide live in assisted living set- tings (National Center for Assisted Living, 2013). The cleaning and sanitizing of slicing equipment is particularly important in senior living facilities. Outbreaks of gastroenteritis at long-term care facilities have been associated with Salmonella, Campylobacter , Staphylococcus, Escherichia and Clostridium (Standaert, Hutcheson, & Schaffner,1994; Tallis, Ng, Ferreira, Tan, & Griffith, 1999). Twenty percent of people over 80 reside in long- term care facilities as well as 5% of people over the age of 65 (Buzby, 2002). Residents of long-term care facilities are 4 times more likely to die from gastroenteritis than those living within the community (Frenzen, 2003). Nearly 18% of deaths, involving gastroenteritis, occurred in nursing homes (Frenzen, 2004). Two percent of all foodborne outbreaks reported have occurred within geriatric facilities (Levine, Smart, Archer, Bean, & Tauxe, 1991). * Corresponding author. Center for Food Safety, Department of Food Science, University of Arkansas, 2650 North Young Avenue, Fayetteville, AR 72704-5690, USA. Tel.: þ1 479 575 4678; fax: þ1 479 575 6936. E-mail address: sricke@uark.edu (S.C. Ricke). URL: http://cfs.uark.edu/ 1 Current address: Food Safety Research Group, Korea Food Research Institute, Seongnam-si, Gyeonggi-do, Republic of Korea. Contents lists available at ScienceDirect Food Control journal homepage: www.elsevier.com/locate/foodcont http://dx.doi.org/10.1016/j.foodcont.2014.02.027 0956-7135/Ó 2014 Elsevier Ltd. All rights reserved. Food Control 42 (2014) 242e247