Detection and quantification of Salmonella in fresh vegetables in Perak, Malaysia

Abstract

The eating of fresh and minimally processed vegetables is getting popular among Malaysians. This trend poses an increased risk of food poisoning associated with the consumption of fresh produce contaminated with pathogenic bacteria. Salmonellosis is a foodborne disease caused by several non-typhoidal Salmonella enterica serovars, predominantly serovars Enteritidis and Typhimurium. The present study aimed to determine the prevalence of Salmonella spp., S. enterica serovar Enteritidis and S. enterica serovar Typhimurium in fresh leafy vegetables such as cabbages (n = 40), lettuces (n = 20), and fruit vegetables such as tomatoes (n = 40), carrots (n = 40) and cucumbers (n = 40), which were sold by three different hypermarkets and a wet market in Kampar, Perak, Malaysia. The study was performed over a period of 13 months (January 2018 to January 2019). A combination of most probable number-multiplex polymerase chain reaction (MPN-mPCR) method was used to quantify the concentrations of Salmonella spp., S. enterica serovar Enteritidis and S. enterica serovar Typhimurium in the examined samples. The results of this study demonstrated that of the vegetables tested, tomatoes, carrots and lettuces were not contaminated by Salmonella spp., S. enterica serovar Enteritidis and S. enterica serovar Typhimurium. However, the presence of Salmonella spp. was detected in 3.3% of cabbages from the hypermarket, with estimated microbial loads ranging from <3.0 MPN/g to 15.0 MPN/g. On the other hand, S. enterica serovar Typhimurium was detected in 10.0% of the cucumbers from hypermarkets and 20% of them from the wet market. Their microbial loads were ranging from <3.0 MPN/g to >1,100 MPN/g. This indicated that cabbages and cucumbers could be the potential sources of salmonellosis. Therefore, the monitoring of food safety and hygienic practices should be strictly enforced by relevant government agencies to avoid potential poisoning by foodborne pathogens.