Importance of Hygiene, Surface Cleaning Underscored by Listeriosis Outbreaks

Carolyn Cokes, MPH, of the Bureau of Communicable Disease at the New York City Department of Health and Mental Hygiene, and colleagues, emphasize that routine and thorough cleaning of food contact surfaces in hospital kitchens is an essential practice to reduce opportunities for cross-contamination of foods with L. monocytogenes, in a study published in a recent issue of Infection Control and Hospital Epidemiology.

As Cokes, et al. (20110) explain that because no foodborne illness risk management guidelines exist specifically for U.S. hospitals, a survey of New York City hospitals was conducted to characterize policies and practices after a listeriosis outbreak occurred in a NYC hospital. From February through April 2009, NYCs 61 acute-care hospitals were asked to participate in a telephone survey regarding food safety practices and policies, specifically service of high-risk foods to patients at increased risk for listeriosis. The researchers report that five patients with medical conditions that put them at high risk for listeriosis had laboratory-confirmed Listeria monocytogenes infection. The Listeria outbreak strain was isolated from tuna salad prepared in the hospital. Overall, 81perent of 54 respondents reported serving ready-to-eat deli meats to patients, and 100 percent reported serving prepared ready-to-eat salads. Pregnant women, patients receiving immunosuppressive drugs, and patients undergoing chemotherapy were served ready-to-eat deli meats at 77 percent, 59 percent, and 49 percent of hospitals, respectively, and were served prepared ready-to-eat salads at 94 percent, 89 percent, and 73 percent of hospitals, respectively. Only 4 of 16 respondents reported having a policy that ready-to-eat deli meats must be heated until steaming hot before serving.

The researchers report that a sanitary inspection of the hospital kitchen was conducted by inspectors from the NYC Office of Environmental Investigations (OEI) and environmental swab samples were collected from food-contact surfaces, including countertops, cutting boards and a food slicer. On the basis of initial epidemiologic data, a follow-up investigation was conducted to perform a Hazard Analysis and Critical Control Points (HACCP)based food preparation review of the tuna salad and the turkey sandwiches and to collect samples of these items. OEI sanitarians returned to collect additional environmental surface samples for Listeria analysis. After being informed of the NYC DOHMHs preliminary environmental, laboratory and epidemiologic results, inspectors from the New York State (NYS) Agriculture and Markets (A&M) and the NYS Department of Health (DOH) visited hospital X; 25 environmental surface swab samples from cooking and storage surfaces, kitchen equipment, vents, drains and floors as well as more than 20 food samples were collected and analyzed for Listeria contamination.

Cokes, et al. (20110) report that one of the two environmental samples positive for L. monocytogenes was from a can-opener base, which was mounted on a table in the area of the kitchen where cold salads were prepared and was routinely used to open cans of tuna for tuna salad. The other positive environmental swab sample was collected from a floor drain near the 100-quart mixer used to mix the tuna salad. In accordance with NYS DOH recommendations, the facility contracted with an outside consultant for cleaning and remediation, followed by collection and testing of environmental swab samples, all of which were negative for L. monocytogenes.

The researchers emphasize, "Because patient groups at high risk for severe outcomes of L. monocytogenes infection comprise a high proportion of hospital patient populations, the absence of guidelines in hospital food service practices for prevention of L. monocytogenes contamination and growth is concerning. We recommend that hospitals implement policies to avoid serving certain foods to patients at risk for listeriosis. If these foods are served in patient meals, food preparation practices and policies to minimize the risk for Listeria contamination should be universally employed. In addition, routine and thorough cleaning of food contact surfaces in hospital kitchens is an essential practice to reduce opportunities for cross-contamination of foods with L. monocytogenes, an environmentally persistent pathogen."

Reference: Cokes C, France AM, Reddy V, Hanson H, Lee L, Kornstein L, Stavinsky F and Balter S. Serving High-Risk Foods in a High-Risk Setting: Survey of Hospital Food Service Practices after an Outbreak of Listeriosis in a Hospital. Vol. 32, No. 4. April 2011.