Time course study on the growth of Salmonella Enteritidis on raw vegetables used in sandwiches

A time course study on the growth of Salmonella Enteritidis on raw vegetables used a part of the ingredients for sandwiches at room temperature and at 4°C, with initial microbial load of log 3 and log 1 spiked onto the lettuce and cucumber slices. The growth of Salmonella Enteritidis were higher at room temperature and were dose dependent. The information obtained in this study may contribute towards food handling solutions in order to be able to control the food safety of fresh produce

Prevalence of Salmonella spp. in chicken and beef from retail outlets in Malaysia

The prevalence of Salmonella in chicken and beef sold in retails outlets in Malaysia was determined by analysing 312 raw beef and chicken meat samples including their processed products. Samples purchased from supermarkets, butcher shops and wet market, which being classified into raw, minced and processed chicken and beef. A total of 86 (27.6%) samples were found positive for Salmonella spp., with chicken meat samples (40.4%) showed greater presence compared to beef (15.4%). Highest presence of Salmonella were detected from wet market samples (35.4%), followed by supermarket (26.9%) and butcher shop (21.3%). The prevalence of Salmonella were higher in unpacked chicken meat (84.8%), followed by unpacked beef (27.8%). Salmonella serovars were identified as S. Enteritidis, S. Hadar, S. Dublin, S. Anatum, S. Stanley, S. Gallinarum, S. Choleraesuis and S. Typhimurium. Detection of 8 Salmonella serovars showed possibilities of cross contamination in various sources either at slaughtering house, processing plant or until storage at retails level. Improper cooking method on meats and hygiene practices prior to consume should be avoided in order to ensure food safety before ingestion

Prevalence and detection of Vibrio spp. and Vibrio cholerae in fruit juices and flavored drinks

In this study, the prevalence of Vibrio spp. and V. cholerae in flavored drinks and fruit juices sold at hawker stalls and in restaurants were determined using the most probable number (MPN) method and polymerase chain reaction (PCR) assay. One hundred and twenty drinks samples of four types of drinks (Iced Milk Rose Syrup, n=25; Iced Milk Corn Syrup, n=20; Apple Juice, n=37 and Iced Carrot Milk, n=28) were collected at two different settings; mainly hawker stalls and restaurants. Upon analysis, the prevalence of Vibrio spp. and V. cholerae in fruit juices and flavored drinks for hawker stalls were 93.3% and 36.7%, respectively whereas for the restaurants, were 93.3% and 20% respectively. Overall, the prevalence of Vibrio spp. and V. cholerae in all the drink samples were 93.3% and 28.3% respectively, highlighting the needs for the improvement of the hygiene and sanitation practice in the settings being studied

Prevalence and quantification of Vibrio parahaemolyticus in raw salad vegetables at retail level

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\ud 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 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

Thermophilic Campylobacter spp. occurrence on chickens at farm, slaughter house and retail

The aim of this study was to investigate the occurrence of campylobacters in chicken at farms (close-house system and open-house system), slaughtering (conventional slaughterhouse and processing plant) and retail (wet market and supermarket). Campylobacter spp. was not found in cloacal swabs in chickens aged of 4 weeks in farms with close-house system. Campylobacter spp. was found in cloacal swabs (95.0%) in four weeks old chicken in farms with open-house systems. End-slaughtering samples from conventional slaughterhouse and processing plant were contaminated with Campylobacter spp. at 84.0% and 94.0%, respectively. Campylobacter contamination on wet market and supermarket samples with 78.0% and 92.0%, respectively. Close-house system at farm level was able to prevent or delay Campylobacter spp. colonization in chickens but contamination by Campylobacter spp. at retail level was still high. Therefore, monitoring of Campylobacter spp. in chicken products at retail level is crucial to reduce risk of human ingestion of Campylobacter spp. through chicken products

Lactic Acid Bacteria Producing Sorbic Acid and Benzoic Acid Compounds from Fermented Durian Flesh (Tempoyak) and Their Antibacterial Activities Against Foodborne Pathogenic Bacteria

Background and Objective: Antibacterial compounds produced by lactic acid bacteria are believed to replace functions of chemical preservatives. The objectives of this study were to identify lactic acid bacteria, which produced antibacterial compounds, from fermented durian flesh (tempoyak) and to assess antibacterial activities of the isolates. Material and Methods: Two bacterial identification techniques were used, including API 50 CHL kit with supplementary medium and matrix-assisted laser desorption ionisation-time of flight mass spectrometry (MALDI-TOF/MS). Results and Conclusion: Four various lactic acid bacteria strains of Lactobacillus buchneri, Lactobacillus plantarum, Lactobacillus brevis I and Lactobacillus acidophilus I were identified using API 50 CHL Kit and five various others of Lactobacillus paracasei DSM 2649, Lactobacillus buchneri DSM 20057T, Lactobacillus parabuchneri DSM 57069, Lactobacillus paracasei DSM 20020 and Lactobacillus farcimini CIP 103136T using MALDI-TOF/MS. Cell-free supernatant extracted from Lactobacillus plantarum, Lactobacillus buchneri, Lactobacillus brevis I and Lactobacillus acidophilus I included strong inhibitory effects against Vibrio cholera O1 (Inaba type), Vibrio cholera O139 (Bengal type), Vibrio parahaemolyticus ATCC 17802, Escherichia coli ATCC 11795, Escherichia coli O157, Salmonella typhimurium ATCC 14028 and a total of 23 serotypes of Salmonella spp. associated with outbreaks of food poisoning from raw chicken, egg shell and water samples. Only Lactobacillus buchneri DSM 20057T was identified by MALDI-TOF/MS as a strain producing sorbic and benzoic acids. This strain can potentially be used as food preservative to decrease growth of foodborne pathogenic bacteria

Bacillus cereus and Bacillus thuringiensis in ready-to-eat cooked rice in Malaysia

Bacillus cereus (B. cereus) isolates are toxigenic and can cause food poisoning. Cooked rice is a potentially hazardous food, especially in tropical countries. The aim of this study was to determine the prevalence of B. cereus and B. thuringiensis in raw and cooked rice marketed in Selangor, Malaysia. In this research combination of Most Probable Number - Polymerase Chain Reaction (MPN-PCR) was used to detect gyrB gene in B. cereus and B. thuringiensis. Five local varieties of raw rice samples were negative for B. thuringiensis but all (100%) were positive for B. cereus. A total of 115 cooked rice samples (nasi lemak, nasi briyani, nasi ayam and nasi putih) were studied for the presence of B. cereus and B. thuringiensis. Nasi ayam was found to have the highest prevalence (100%) of B. cereus compared to nasi putih (76.2%) and nasi lemak (70.4%). Nasi briyani had the lowest prevalence (50%) of B. cereus. The frequencies of B. thuringiensis were found to be 10, 30 and 35.2 % in nasi putih and nasi ayam, nasi briyani and nasi lemak, respectively. The range of B. cereus and B. thuringiensis in the samples was from 1100 MPN/g) while nasi ayam showed less contamination (460 MPN/g) with B. cereus which was significantly different (P 1100, 93, 9.2 and 3.6 MPN/g, respectively

Effect of detergents as antibacterial agents on biofilm of antibiotics-resistant Vibrio parahaemolyticus isolates

Vibrio parahaemolyticus (V. parahaemolyticus) is a halophilic, Gram-negative human pathogen known as a leading cause of seafood-derived food poisoning. Due to high contamination rate of seafood in Asian countries, V. parahaemolyticus is considered as a food safety concern. V. parahaemolyticus is able to produce biofilm which is more resistant toward disinfectants and antibodies than its planktonic form. Thirty six V. parahaemolyticus isolates from seafood were tested for their susceptibility using 18 different antibiotics. Two V. parahaemolyticus isolates were resistant to bacitracin, chloramphenicol, rifampin, ampicillin, vancomycin, nalidixic acid, penicillin and spectinomycin. Fourteen V. parahaemolyticus isolates were found to be resistant to bacitracin, tetracycline, rifampin, ampicillin, vancomycin, penicillin and spectinomycin. The remaining two isolates were resistant to more than 2 antibiotics. Majority of the V. parahaemolyticus isolates (97.2%) showed MAR index > 0.2, indicating that these isolates were originated from high risk sources. To investigate effect of three common detergents on antibacterial-resistant V. parahaemolyticus, 16 V. parahaemolyticus isolates resistant to more than 7 antibiotics were selected. V. parahaemolyticus (ATCC 17802) was used as reference strain. Detergents were tested for their minimum inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) and time–kill curves were constructed to assess the concentration between MIC and bactericidal activity of detergents. Detergents D1 (Linear alkyl benzene based) was found to be the most effective with MIC and MBC ranged between 97.656 and 1562.5 μg/ml and 781.25–3125 μg/ml, respectively. The time–kill curves demonstrated that the bactericidal endpoint for resistant V. parahaemolyticus isolates reached after 30 min incubation with D1 at concentration 8 × MIC. The isolate VP003 was killed at 8 × MIC within 0.5 h and the reduction in CFU/ml was 3 log units (99.9%). V. parahaemolyticus biofilms were formed in 96 wells microtiter plates at 37 °C and 24 h-old biofilm were used to test antibacterial activity of detergents. Results showed that biofilm-producing ability of antibacterial-resistant V. parahaemolyticus isolates were inhibited at 1562.5–6250 μg/ml of D1 and eradicated at 3125 – ≥50,000 μg/ml of D1. Detergents showed potential antimicrobial activity against V. parahaemolyticus

Antibiotic resistance and biosafety of Vibrio cholerae and Vibrio parahaemolyticus from freshwater fish at retail level

A total of 49 isolates of V. parahaemolyticus and 8 isolates of V. cholerae isolated from freshwater fish of patin (Pangasius hypopthalmus) and red tilapia (Oreochromis sp.) were purchased from different retail level in Selangor, Malaysia. All of the isolates showed a multiple resistances towards all 15 antibiotics tested. Some of the isolates show a high resistance to different antibiotics including bacitracin, vancomycin, tetracycline, furazididone, cephalothin and erythromycin. However, both species was susceptible towards imipenem. Overall antibiotics resistance patterns of all isolates were resistant from 2 to 14 resistance patterns with multiple antibiotic resistance (MAR) index ranging from 0.13 to 0.93 respectively. As the results obtained in the dendrogram produced from both species had indicates that these antibiotics were intensively used whether in the aquaculture farm through feeds during culture or at the hatchery production of seed. Thus, this study will provides an essential information of the MAR index and also the clustering analysis in order to determine the biosafety of Vibrio spp. in freshwater aquaculture fish sold at different retail level in Malaysia