Investigation Of Listeria Spp. In Korean Foods - Brief Article

Nutrition Research Newsletter, July, 2001

Due to recent outbreaks of listeriosis caused by L. monocytogenes, much interest has been generated in investigating the behavior of this bacterium in foods. The mortality rate following infection of L. monocytogenes is much greater than that of other pathogens, including Escherichia coli 0157:H7. L. monocytogenes is one of the food pathogens that has a very wide growth temperature range (1-44 [degrees] C), therefore allowing contamination of refrigerated foods. Currently, in Korea, there has been little information on the occurrence of L. monocytogenes in various foods.

To further evaluate L. monocytogenes contamination in foods in Korea, a study was performed using a total of 410 food samples collected from randomly selected foodmarkets. The presence of Listeria spp. as identified by the use of conventional U.S. Department of Agriculture protocol, and presumptive strains were identified by morphological, cultural, and biochemical tests according to Bergey's manual and confirmed by API-Listeria kit.

It was found that 11.2% of the samples were contaminated with Listeria spp. The highest prevalence of Listeria spp. was found in the raw chicken and beef samples. Only beet, chicken, pork, frozen foods including pork cutlet patties and dumplings, and sausage were contaminated with L. monocytogenes. L. innocua was the most predominant strain isolated from the foods studied. Also, an antibiotic susceptibility test showed that Listeria spp. isolates were very susceptible to the antibiotics tested.

These findings suggest that a serious threat of food safety could be due to the presence of L. monocytogenes from commercially available refrigerated or frozen foods. There is a need for more precautions to be taken against the potentially fatal infection of L. monocytogenes.

Y. Choi, S. Cho, B. Park, et al. Incidence and characterization of Listeria spp. from foods available in Korea. Journal of Food Protection; 64:554-558 (April 2001) [Correspondence: Deog-Hwan Oh, Phone/Fax: 82-33-250-6457; E-mail: deoghwa@cc.kangwon.ac.kr].