Practical application of bacteriophage in food manufacturing facilities for the control of Listeria sp.

Listeria monocytogenes is a foodborne pathogen with the ability to persist and form biofilm matrices in processing environments of food manufacturing facilities. Bacteriophages are bacterial viruses with host specific lethality. Published research on the application of phage to control Listeria sp. in manufacturing environments is limited. In this study, we have assessed the capacity of bacteriophage P100 (Listex (TM)) to reduce incidence of Listeria sp. in the ready-to-eat (RTE) environment of refrigerated (4 degrees C) and ambient (20 degrees C) temperature facilities using two different application strategies. A moderate application applied as a single treatment every 24 hr over three days (2 x 10(7) PFU/ml) and an intensified application applied once every 6 hr over a 24 hr period (1 x 10(8) PFU/ml). Environmental nonfood contact surface (NFCS) samples were collected and analyzed for the presence of Listeria sp. before and after treatment. When the moderate treatment protocol was applied the incidence of positives decreased from 51.3 to 17.5% in the 4 degrees C environment and from 67.5 to 23.1% in the 20 degrees C production area. For the intensified phage treatment method, the initial positive rate in the 4 degrees C environment ranged from 5 to 47.5%, with an overall 43% reduction in Listeria sp. In the 20 degrees C facility, initial environmental Listeria sp. ranged from 15 to 50%, with an overall reduction of 32% after treatment with phage P100. Data indicate the application of Listeria specific phage P100 in RTE food production environments by either the moderate or intensified application method can reduce incidence and be considered an additional intervention strategy for controlling this pathogen on NFCS.