Food Protection Trends - September 2012 - (Page 512)

ARTICLES Copyright© 2012, International Association for Food Protection 6200 Aurora Ave., Suite 200W, Des Moines, IA 50322-2864 Food Protection Trends, Vol. 32, No. 9, Pages 512–521 Investigating Contamination of Bulk Tank Milk with Listeria monocytogenes on a Dairy Farm J. C. F. PANTOJA,* A. C. O. RODRIGUES, C. HULLAND, D. J. REINEMANN and P. L. RUEGG Dept. of Dairy Science, University of Wisconsin-Madison, 1675 Observatory Drive, Madison, WI 53706, USA INTRODUCTION SUMMARy The objectives were to identify the source of Listeria monocytogenes in bulk tank milk (BTM), and to assess characteristics of Petrifilm Environmental Listeria (PEL) for detection of this pathogen in farm samples. Environmental and milk samples were collected from a dairy during two sampling periods. Follow-up samples of daily BTM and milk filters were collected. Isolates of L. monocytogenes were compared by use of Pulsed Field Gel Electrophoresis. Samples were plated on PEL and results classified into positive or negative. Of samples collected during the two sampling periods, L. monocytogenes was isolated from 66% of milk filters (19 of 29), 16% of BTM (7 of 44), 6% of water samples (two of 33) and one of 18 in-line milk samples. Except for one isolate, all were identical and of the same molecular type. Contamination of BTM with L. monocytogenes most likely originated from a common source, and results indicate that farms can develop persistent sources of contamination.The sensitivity of the PEL was high (100 and 74.1% for environmental and milk samples, respectively), but there was a high proportion of false-positive results and low specificity.These limitations need to be considered when using the PEL for on-farm screening of L. monocytogenes. A peer-reviewed article *Author for correspondence: Phone: +1 608.263.3498; Fax: +1 608.263.9412 E-mail: josecarlospantoja@hotmail.com Diseases caused by foodborne pathogens impact the health of millions of people worldwide. It has been estimated that in the United States approximately 48 million foodborne disease cases result in 128,000 hospitalizations and 3,000 deaths each year (4). Among foodborne pathogens, Listeria monocytogenes has been considered an emerging public health problem because of its pathogenicity and ability to contaminate food. Listeria monocytogenes is capable of multiplying at temperatures ≤ 7°C and surviving in environments with a wide range of pH values (4.3 to 10) and high salt concentrations (15). Various species of Listeria are commonly found in soil, decaying vegetation, and water, and well as being part of the fecal flora of animals and humans. In dairy cattle, L. monocytogenes can result in several clinical presentations, including encephalitis, septicemia, abortion, and mastitis (14). Mastitis caused by Listeria is infrequent, but infected mammary glands can shed this pathogen for periods as long as 12 months (21). Listeria monocytogenes is present in the dairy farm environment and 512 FOOD PROTECTION TRENDS | SEPTEMBER 2012 http://www.foodprotection.org/files/food-protection-trends/Sep-12-Pantoja.pdf

Table of Contents for the Digital Edition of Food Protection Trends - September 2012

Food Protection Trends - September 2012
Contents
Sustaining Members
From Your President
Commentary from the Executive Director
Investigating Contamination of Bulk Tank Milk with Listeria monocytogenes on a Dairy Farm
General Interest Paper: Environmental Monitoring and Decontamination of Food Processing Facilities
Call for Nominations – 2013 Secretary
New Members
What’s Happening in Food Safety
Industry Products
Coming Events
Advertising Index
Journal of Food Protection Table of Contents
Membership Application

Food Protection Trends - September 2012