Consumption of salad vegetables has increased significantly over the past two decades due to their health benefits. However, eating fresh vegetables carries a number
of risks, especially if the vegetables are contaminated with
pathogenic microorganisms (3). Among the pathogens
most often associated with vegetables and salads is Listeria monocytogenes (4, 5). According to Ieren et al. (6), the
highest incidence of this pathogenic microorganism occurs in cabbage, green salads, and tomatoes. The high
prevalence of L. monocytogenes in fresh cabbage (95.8%) and
ready-to-eat coleslaw (80.1%) in the Accra metropolis indicates that consumers of commercially prepared coleslaws
have been extensively exposed to this pathogen (7). Listeria monocytogenes as a psychotropic organism is capable of
growth at refrigeration temperatures, which means that
low numbers of initially contaminating cells may proliferate and become hazardous if they are present on or transferred to ready-to-eat foods stored in refrigerators (8). Consequently, the consumption of minimally processed vegetables contaminated with L. monocytogenes may cause listeriosis in humans. An outbreak of listeriosis in Canada in
1981 was linked to the consumption of coleslaw contaminated with L. monocytogenes (9), and one of the largest outbreaks of listeriosis, which occurred in 2011 and included
several states in the U.S., was caused by consumption of
fresh cantaloupe (10)