Infections by virulent strains of Vibrio parahaemolyticus are frequently reported in Southeast Asia. This is due to the frequent seafood contamination by virulent strains. In this study conducted from 2008 to 2011, seafood like fish, shrimp, squid, crab, and molluscan shellfish were purchased from provinces in Thailand and three Southeast Asian countries and examined for the prevalence of three genetic markers of V. parahaemolyticus (species-specific gene: toxR gene, virulence genes: tdh and trh genes). An enrichment culture of seafood was examined for these markers using PCR methods. Molluscan shellfish showed a high frequency of contamination in Thailand. The shellfish harvested from the Gulf of Thailand were significantly more contaminated with virulence genes than those from the Andaman Sea. The seafood purchased from three Southeast Asian countries was positive for the three markers of V. parahaemolytcus at differing frequencies. The virulence markers (tdh and trh markers) were frequently detected in molluscan shellfish from Vietnam (17.9 and 8.0%, respectively), Malaysia (11.1 and 16.7%), and Indonesia (9.1 and 13.6%). These data suggest that the molluscan shellfish sold in Southeast Asian markets are highly contaminated with virulent strains of V. parahaemolyticus.
E. coli O157:H7 is associated with life threatening diseases such as hemorrhagic colitis (HC), hemolytic uremic syndrome (HUS) and thrombotic thrombocytopenic purpura (TTP). Raw milk is considered a high risk food as it is highly nutritious and serves as an ideal medium for bacterial growth. The aim of this study was to investigate the prevalence of E. coli O157:H7 in raw cow, goat and buffalo milk samples. MPN-PCR method targeting the major virulence rfbE gene and fliCH7gene of E. coli O157:H7 was used. Total of 177 raw milk samples were collected from local dairy farms in the state of Selangor, Malaysia. The highest prevalence of E. coli O157:H7 was found in raw cow milk (18.75%). E. coli O157:H7 was detected in 7.32% and 3.57% of raw goat and buffalo milk, respectively. The estimated quantity of E. coli O157:H7 in raw cow, goat and buffalo milk ranged from
Listeria monocytogenes (L. monocytogenes) is an important foodborne pathogen which can cause foodborne listeriosis with high mortality rates especially in susceptible population groups such as pregnant women, elderly and immunocompromised individuals. The biosafety level of L. monocytogenes in chicken offal has becomes a great concern as chicken offal is a cheap source of protein and it is often served as side dishes in South East Asian countries. In Malaysia, the consumption of chicken offal has almost doubled from 5 g per capita per day in the early 1980s to 9 g per capita per day in 2009. In this study, risk assessment was conducted to estimate the risk of acquiring listeriosis from consumption of chicken offal in Malaysia. A microbial survey on the prevalence and concentration of L. monocytogenes in chicken offal were carried out in Selangor, Malaysia over a one-year period (November 2010 to October 2011). It was assumed that there were no seasonal changes in the prevalence and consumption pattern all year round. Assuming that 5.6 million people in Selangor, Malaysia consume a single serving (125 g) of chicken offal per week, it is estimated that in a year there could be 0.61 cases and 1.98 × 10-4 cases of listeriosis per 100,000 population of pregnant woman and immunocompromised individual, respectively. However, the potential for getting listeriosis among the healthy population was very low, only 1.39 × 10-8 cases per 100,000 population. This study demonstrated risk assessment model not only used as a tool to estimate the risk of acquiring illness but it can influence public health surveillance and providing data in setting appropriate level of protection.
A total of 216 chicken offal samples (chicken liver = 72; chicken heart = 72; chicken gizzard = 72) from wet markets and hypermarkets in Selangor, Malaysia, were examined for the presence and density of Listeria monocytogenes by using a combination of the most probable number and PCR method. The prevalence of L. monocytogenes in 216 chicken offal samples examined was 26.39%, and among the positive samples, the chicken gizzard showed the highest percentage at 33.33% compared with chicken liver (25.00%) and chicken heart (20.83%). The microbial load of L. monocytogenes in chicken offal samples ranged from <3 to 93.0 most probable number per gram. The presence of L. monocytogenes in chicken offal samples may indicate that chicken offal can act as a possible vehicle for the occurrence of foodborne listeriosis. Hence, there is a need to investigate the biosafety level of chicken offal in Malaysia.
Nine Escherichia coli O157: H7/- strains isolated primarily from non-clinical sources in Thailand and Japan carried the stx(2) gene but did not produce Stx2 toxin in a reversed passive latex agglutination (RPLA) assay. A strain (EDL933) bearing a stx(2) phage (933W) was compared to a strain (Thai-12) that was Stx2-negative but contained the stx(2) gene. To study the lack of Stx2 production, the Thai-12 stx(2) gene and its upstream nucleotide sequence were analyzed. The Thai-12 stx(2) coding region was intact and Stx2 was expressed from a cloned stx(2) gene using a plasmid vector and detected using RPLA. A lacZ fusion analysis found the Thai-12 stx(2) promoter non-functional. Because the stx(2) gene is downstream of the late promoter in the stx(2) phage genome, the antitermination activity of Q protein is essential for strong stx(2) transcription. Thai-12 had the q gene highly homologous to that of Phi21 phage but not to the 933W phage. High-level expression of exogenous q genes demonstrated Q antitermination activity was weak in Thai-12. Replication of stx(2) phage was not observed in Stx2-negative strains. The q-stx(2) gene sequence of Thai-12 was well conserved in all Stx2-negative strains. A PCR assay to detect the Thai-12 q-stx(2) sequence demonstrated that 30% of O157 strains from marketed Malaysian beef carried this sequence and they produced little or no Stx2. These results suggest that stx(2)-positive O157 strains that produce little or no Stx2 may be widely distributed in the Asian environment.
The aim of this study was to assess the most probable number-polymerase chain reaction (MPNPCR) 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 artificial and naturally contaminated samples. Based on recovery of L. monocytogenes from artificially 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.
This study aimed to determine the prevalence Listeria monocytogenes in raw chicken meat samples at hypermarkets and wet markets. Chicken drumsticks, breasts, and thighs were randomly selected. The most probable number (MPN) PCR method was used to quantify the L. monocytogenes in the samples. Listeria monocytogenes was detected in 20% of the samples. Occurrence of L. monocytogenes was highest in breast (42.03%) followed by drumstick (11.27%) and thigh (7.14%). Samples from hypermarkets showed higher occurrence (25.71%) of L. monocytogenes compared with wet markets (14.29%). The density of L. monocytogenes found in samples ranged from <3.0 to 16 MPN•g(-1). The presence of L. monocytogenes in raw chicken meat is unwanted but unpreventable. Thus, further research on the processing method to reduce and eliminate this kind of bacteria in chicken meat before consumption is necessary. The presence of L. monocytogenes in chicken samples suggests the importance of this pathogen in chicken. Thus, more study is needed to find ways to eliminate this pathogen from poultry.
Vibrio parahaemolyticus is a main foodborne disease in seafood and generally seafood is
easily deteriorates in quality of color and flavor. In this study, clove (Syzygium aromaticum)
extract shows potent antibacterial activity against growth of antibiotics resistant Vibrio
parahaemolyticus on seafood samples (cockles and shrimps). Vibrio parahaemolyticus was
artificial contaminates on the samples with 106 CFU/ml. The samples were treated with different
concentration of cloves extract with 10 mg/ml which are 0.5%, 5% and 10% concentration
from methanol food grade extraction in 0 hr, 5 min, 10 min, 15 min, 30 min, 60 min and
120 min. Tab water and deionized water were selected as a negative control. As a result, the
amount of 10 % cloves managed to mitigates the number of V. parahaemolyticus on seafood
samples in 5 minutes and 15 min on both samples. Therefore, our results signify the fact that
cloves can be apply as natural sanitizer which could meet consumer demands for safe and
traditionally consumed either raw without any undesirable effect when applied in the seafood
system industries.
The organic foods’ market is becoming one of the rapidly growing sections in agricultural economies in the world. During the last two decades, food-borne outbreaks associated with fresh produce have rapidly increased. E. coli O57:H7, the caustic agent of acute hemorrhagic diarrhea and abdominal cramps, is mainly associated with meat and poultry product outbreaks but frequent outbreaks linked to the consumption of vegetables have been reported. The aim of this study was to investigate prevalence of E. coli O157:H7 in some organic foods. A total of 230 organic food samples including four-winged bean, tomato, white radish, red cabbage, chinese cabbage, lettuce, cucumber and chicken form retailed groceries and supermarkets in Malaysia were investigated. Low prevalence of E. coli O157:H7 was detected in organic vegetables and chickens. The estimated quantity of E. coli O157:H7 in all samples ranged from 2400 MPN/g. The overall MPN/g estimate of E. coli O157:H7 in the samples from organic groceries was higher than supermarket with the maximum of >2400 MPN/g. Most of the samples from supermarket showed a minimum of
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.
The aim of the present study was to examine the prevalence of thermophilic Campylobacter spp. (Campylobacter jejuni and Campylobacter coli) in soil, poultry manure, irrigation water, and freshly harvested vegetables from vegetable farms in Malaysia. C. jejuni was detected in 30.4% and 2.7% of the soil samples, 57.1% and 0% of the manure samples, and 18.8% and 3% of the vegetable samples from farm A and farm B, respectively, when using the MPNPCR method. Campylobacter spp. was not found in any of the irrigation water samples tested. Therefore, the present results indicate that the aged manure used by farm A was more contaminated than the composted manure used by farm B. Mostly, the leafy and root vegetables were contaminated. C. coli was not detected in any of the samples tested in the current study. Both farms tested in this study were found to be contaminated by campylobacters, thereby posing a potential risk for raw vegetable consumption in Malaysia. The present results also provide baseline data on Campylobacter contamination at the farm level.
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 degrees 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.
Listeria monocytogenes (L. monocytogenes) is a gram positive food-borne pathogen that is able to form biofilm on food factory surfaces. Formation of biofilm makes the bacteria much more resistance to environmental stresses such as disinfectant. The extracellular polymeric matrix (biofilm structure) which is mostly comprised of sticky extracellular polysaccharides (EPS) and proteins can protect bacteria in a harsh condition. The efficiency of four disinfectants on removing L. monocytogenes biofilm was investigated. Five concentration levels (100, 50, 25, 12.5, and 6.25%) of disinfectants were tested. In the microtitre assay, the optical density at 595 nm CV-OD595 value, was used to measure the amount of remained biofilm after 24 h. Results showed that disinfectants did not have significant effect on removing L. monocytogenes biofilm. Formation of L. monocytogenes biofilm significantly decreased the efficiency of disinfectants. Biofilm produced by strain number 9 showed higher resistance to disinfectant. Low concentrations (