a b s t r a c tA range of commercially available vegetables (n = 306) that are consumed in the minimally processed state in Malaysia was examined for the presence of Listeria spp. and Listeria monocytogenes to provide information on the occurrence of such organisms in these vegetables. Analysis was carried out using the most probable number-polymerase chain reaction (MPN-PCR) method. It was found that Listeria spp. and L. monocytogenes could be detected in 33.3% and 22.5% of the vegetables respectively. L. monocytogenes was more frequently detected in Vigna unguiculata (Japanese parsley) at 31.3% and Oenanther stolonifera (yardlong bean) at 27.2%.

The main aim of this study was to combine the techniques of most probable number (MPN) and polymerase chain reaction (PCR) for quantifying the prevalence and numbers of Campylobacter spp. in ulam, a popular Malaysian salad dish, from a traditional wet market and two modern supermarkets in Selangor, Malaysia. A total of 309 samples of raw vegetables which are used in ulam were examined in the study. The prevalences of campylobacters in raw vegetables were, for supermarket I, Campylobacter spp., 51.9%; Campylobacter jejuni, 40.7%; and Campylobacter coli, 35.2%: for supermarket II, Campylobacter spp., 67.7%; C. jejuni, 67.7%; and C. coli, 65.7%: and for the wet market, Campylobacter spp., 29.4%; C. jejuni, 25.5%; and C. coli, 22.6%. In addition Campylobacter fetus was detected in 1.9% of raw vegetables from supermarket I. The maximum numbers of Campylobacter spp. in raw vegetables from supermarkets and the wet market were >2400 and 460 MPN/g, respectively.

The purpose of this study was to investigate the biosafety of Vibrio parahaemolyticus in raw salad vegetables at wet markets and supermarkets in Malaysia. A combination of the most probable number-polymerase chain reaction (MPN-PCR) method was applied to detect the presence of V. parahaemolyticus and to enumerate their density in the food samples. The study analyzed 276 samples of common vegetables eaten raw in Malaysia (Wild cosmos=8; Japanese parsley=21; Cabbage=30; Lettuce=16; Indian pennywort=17; Carrot=31; Sweet potato=29; Tomato=38; Cucumber=28; Four-winged bean=26; Long bean=32). The samples were purchased from two supermarkets (A and B) and two wet markets (C and D). The occurrence of V. parahaemolyticus detected was 20.65%, with a higher frequency of V. parahaemolyticus in vegetables obtained from wet markets (Wet market C=27.27%; Wet Market D=32.05%) compared with supermarkets (Supermarket A=1.64%; Supermarket B=16.67%). V. parahaemolyticus was most prevalent in Indian pennywort (41.18%). The density of V. parahaemolyticus in all the samples ranged from <3 up to >2,400 MPN/g, mostly <3 MPN/g concentration. Raw vegetables from wet markets contained higher levels of V. parahaemolyticus compared with supermarkets. Although V. parahaemolyticus was present in raw vegetables, its numbers were low. The results suggest that raw vegetables act as a transmission route for V. parahaemolyticus. This study will be the first biosafety assessment of V. parahaemolyticus in raw vegetables in Malaysia.

The health risks posed by Salmonella spp., Salmonella Enteritidis and Salmonella Typhimurium through the consumption of raw vegetables and vegetarian burger patties necessitates the needs for the optimization of analytical approach for their detection and enumeration in the raw vegetables, which served as potential vehicles for transmission of these pathogenic microorganisms. We sought to establish a rapid, economic and sensitive method to detect and determine the load of Salmonella spp., Salmonella Enteritidis and Salmonella Typhimurium using the most probable numbers (MPN) in combination with the multiplex polymerase chain reaction (MPCR). From the naturally contaminated one hundred and seventy five samples tested (n = 175), the overall prevalence of Salmonella spp. was 28%, Salmonella Enteritidis was 20% and Salmonella Typhimurium was 14.3%, respectively. The MPN-MPCR is a quantitative method to determine the density of cell concentration of Salmonella in all the samples (Salmonella spp. ranged from <3 to 53 MPN/g; S. Enteritidis ranged from <3 to 24 MPN/g; and S. Typhimurium ranged from <3 to 15 MPN/g). The combination of the MPN-MPCR is an efficient, simple, fast analytical method for the detection and enumeration of Salmonella spp., Salmonella Enteritidis and Salmonella Typhimurium in vegetables and the vegetarian burger patties since it can significantly reduce time and labour with analysis completed within 2 days, as opposed to the traditional confirmation method that can take up to 5 days for unequivocal identification of species.

The objectives of our study were to investigate the Salmonella species contamination in various types of ready‐to‐eat street‐vended dishes or drinks, to isolate Salmonella spp. from clinical samples and to assess the possible relationship between the serotypes isolated from these two different environments. The isolates were characterized by their antibiotic resistance, plasmid profiles and randomly amplified polymorphic DNA (RAPD) sequences. A total of 24 salmonellae, belonging to seven different serotypes, were isolated from 129 different street‐vended foods and drinks and 12 clinical samples (rectal swabs). The encountered serotypes from street foods were Salmonella Biafra (n = 8), Salmonella Braenderup (n = 3) and Salmonella Weltevreden (n = 1), and from clinical samples were Salmonella Typhi (n = 8), Salmonella Typhimurium (n = 2), Salmonella Paratyphi A (n = 1) and Salmonella Paratyphi B (n = 1). The results showed no similarities in the types of Salmonella serotypes from street food and clinical samples examined. The Salmonella strains were resistant to one or more of the 14 tested antibiotics. Seventeen isolates harbored plasmids, with plasmid sizes ranging from 3.0 to 38.5 MDa. RAPD fingerprinting with primers OPAR3 and OPAR8 produced a combination of 21 fingerprint patterns. The dendrograms generated for the S. Biafra and S. Typhi showed strains of the same serotypes but of very different types of sample and location of sampling clustered together, indicating the possibility of cross contamination during food handling.