Simulation of cross contamination and decontamination of Campylobacter jejuni during handling of contaminated raw vegetables in a domestic kitchen

Campylobacter jejuni was found to occur at high prevalence in the raw salad vegetables examined. Previous reports describe cross-contamination involving meat; here we investigated the occurrence of cross-contamination and decontamination events in the domestic kitchen via C. jejuni-contaminated vegetables during salad preparation. This is the first report concerning quantitative cross-contamination and decontamination involving naturally contaminated produce. The study was designed to simulate the real preparation of salad in a household kitchen, starting with washing the vegetables in tap water, then cutting the vegetables on a cutting board, followed by slicing cucumber and blanching (heating in hot water) the vegetables in 85°C water. Vegetables naturally contaminated with C. jejuni were used throughout the simulation to attain realistic quantitative data. The mean of the percent transfer rates for C. jejuni from vegetable to wash water was 30.1 to 38.2%; from wash water to cucumber, it was 26.3 to 47.2%; from vegetables to cutting board, it was 1.6 to 10.3%; and from cutting board to cucumber, it was 22.6 to 73.3%. The data suggest the wash water and plastic cutting board as potential risk factors in C. jejuni transmission to consumers. Washing of the vegetables with tap water caused a 0.4-log reduction of C. jejuni attached to the vegetables (most probable number/gram), while rapid blanching reduced the number of C. jejuni organisms to an undetectable level

Thermophilic Campylobacter spp. in salad vegetables in Malaysia

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

Quantification of Listeria monocytogenes in salad vegetables by MPN-PCR

The aim of this study was to assess the most probable number-polymerase chain reaction (MPN-PCR) technique for detection of Listeria monocytogenes in salad vegetables in comparison with reference EN ISO 11290-2 and Food Drug Administration Bacteriological Analytical Manual method using artifcial and naturally contaminated samples. Based on recovery of L. monocytogenes from artifcially contaminated samples, MPN-PCR showed a moderate correlation (R=0.67) between spiking concentration and microbial levels which was better than the FDA-BAM method (R=0.642) and ISO 11290-2:1998 method (R=0.655). With naturally contaminated samples, it was found that L. monocytogenes was detected in 25% of the vegetable samples using MPN-PCR; 15% of the samples by the FDA-BAM method and 8% of samples using ISO 11290-2:1998 method. Overall, MPN-PCR was found to be a rapid and reliable method that could facilitate the enumeration of L. monocytogenes in vegetables

Biosafety of Campylobacter jejuni from raw vegetables consumed as ulam with reference to their resistance to antibiotics

Antibiotic resistance in campylobacter is an emerging global public health problem after MRSA and VRE. Fluoroquinolone and macrolide resistance have been found to be more common in this world leading foodborne pathogen. A total of fifty-six isolates of Campylobacter jejuni obtained from raw vegetables which are consumed as ulam (salad) in Malaysia, were tested with 12 antibiotics used clinically and agriculturally. The resistance was determined using the disk diffusion method. Results were determined by hierarchic numerical methods to cluster strains and antibiotics according to similarity profiles. Fifty five C. jejuni isolates from different isolation sites were all clustered together into ten groups. This indicates that the commodities (raw salad vegetables/ulam) where the isolates originated might share a similar source of cross-contamination along the production route. All antibiotics tested correlated and there were four groupings reflecting their mode of actions. Generally, C. jejuni isolates were found to be highly resistant to erythromycin (91.1%) and tetracycline (85.7%). Both agents are popular antibiotics used clinically to treat bacterial infections. On the other hand, the C. jejuni isolates showed high percentage (80.4%) of resistance towards enrofloxacin, an extensively used antimicrobial agent in agriculture practices. This study showed that C. jejuni isolates were highly multi-resistance to as many as 10 antibiotics. Therefore, in terms of biosafety, the presence of antibiotic resistance strains in the food chain has raised concerns that the treatment of human infections will be compromised

Listeria monocytogenes in raw salad vegetables sold at retail level in Malaysia.

A 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%

Assessment of Listeria monocytogenes in salad vegetables through kitchen stimulation study

This study was to investigate the occurrence of cross-contamination and decontamination in the kitchen via Listeria monocytogenes contaminated vegetables during salad preparation. In this study, naturally contaminated produce were used to provide realistic quantitative data as opposed to information obtained through artificial inoculation. The study was designed to simulate the real preparation of salad in kitchens in Malaysia which simply involved washing the vegetables in tap water and cutting them on a chopping board prior to serving. It was found that the mean percentage of transfer rates for L. monocytogenes from vegetables to wash water was 32.4–60.2%; from wash water to cucumber 24.9–66.3%; from vegetables to chopping board 18.9–32.2%; from chopping board to cucumber 5.4–75.3%. Washing of the vegetables in tap water caused a 0.3-log reduction of L. monocytogenes attached to the vegetables

Evaluation of Listeria spp. and Listeria monocytogenes in selected vegetable farms

The aim of the study was to examine the prevalence of Listeria spp. and Listeria monocytogenes in soil, poultry manure, irrigation water, and freshly harvested vegetables from three vegetable farms in Cameron Highlands. A total of 177 samples including environmental and vegetable samples were collected. Among the environmental samples (n = 94), poultry manure was found to have a higher prevalence of Listeria spp. and L. monocytogenes at 77.8% and 61.1% respectively using the MPN-PCR analysis procedure. Soil samples were also found to harbour Listeria spp. and L. monocytogenes at 47.6% and 38.1% respectively. Irrigation water sampled from the farms were found to be free from Listeria spp. Both Listeria spp. and L. monocytogenes were also detected in 24% and 12% of swabs done at the three farms respectively. Among the freshly harvested vegetables, Listeria spp. was detected in cabbages (30%), cucumber (20%), yardlong beans (10%) and carrots (10%) whereas L. monocytogenes was detected in cabbages (10%), yardlong beans (10%) and carrots (10%) using the MPN-PCR analysis procedure. The present results signify that Listeria spp. poses a potential risk for raw vegetable consumption in Malaysia. The study also provides baseline data on Listeria spp. contamination at farm level

Incidence and characterization of Salmonella species in street food and clinical samples

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

Abstracts of National Conference on Research and Developments in Material Processing, Modelling and Characterization 2020

This book presents the abstracts of the papers presented to the Online National Conference on Research and Developments in Material Processing, Modelling and Characterization 2020 (RDMPMC-2020) held on 26th and 27th August 2020 organized by the Department of Metallurgical and Materials Science in Association with the Department of Production and Industrial Engineering, National Institute of Technology Jamshedpur, Jharkhand, India. Conference Title: National Conference on Research and Developments in Material Processing, Modelling and Characterization 2020Conference Acronym: RDMPMC-2020Conference Date: 26–27 August 2020Conference Location: Online (Virtual Mode)Conference Organizer: Department of Metallurgical and Materials Engineering, National Institute of Technology JamshedpurCo-organizer: Department of Production and Industrial Engineering, National Institute of Technology Jamshedpur, Jharkhand, IndiaConference Sponsor: TEQIP-