Prevalence and concentration of Escherichia coli and Salmonella species in fresh vegetables collected from different types of markets in Phnom Penh

Abstract

Freshly-eaten vegetables have become more popular in Cambodian diet. However, these vegetables are also one of the main sources of infection from pathogenic microorganisms if they become contaminated. Outbreaks of foodborne diseases caused by fresh fruits and vegetables have been increasingly reported, raising concerns regarding their safety. Therefore, it is very important to conduct an inquiry into the contamination of fresh vegetables by Escherichia coli and Salmonella spp. This study investigates the presence and concentration of E. coli, total coliforms, and Salmonella in samples of lettuce, saw-leaf herb, and cucumber, collected from different types of market in Phnom Penh. The spread-plate technique was used to detect the number of bacteria in each sample. The results indicate that the incidence of bacterial contamination in fresh vegetables, particularly lettuce and saw-leaf herbs, was higher in the wholesale markets than the other three types of markets. The concentration of E. coli in each of the samples ranged between 2 x 103 and 7 x 105 CFUs/g from the retail markets. The concentration of total coliforms was also found to be quite high. Salmonella was present in almost all leafy vegetable samples but in very few in cucumber samples. Bacteria reduction from the samples by thorough washing under flowing tap water was effective in most cases.