Food Poisoning Outbreaks Research Articles

Food Poisoning Outbreaks among School Children in Terengganu and their Associated Factors

Food poisoning is a public health problem in Malaysia and among the top five communicable diseases in Malaysia. This study aimed to determine the proportion of food poisoning cases involving schoolchildren in Terengganu in 2016 and their associated factors. This was a cross-sectional study using secondary data collected from 21 food poisoning outbreaks among schoolchildren in Terengganu in 2016. The proportion of food poisoning outbreaks involving schoolchildren in Terengganu in 2016 was 63.6%. Ministry of Education (MOE) school had contributed to 95.3% of outbreak cases, 81% occurred at secondary school and 57.1% involved school located in urban district. Poultry (61.9%) was the most common food vehicle, and Salmonella spp. (52.4%) was the most common microbial etiological agent. Urban district schools had the adjusted odds (aOR=1.803; 95% CI: 1.435,2.267; p < 0.001) compared with rural district schools. Non-MOEschoolchildren were more likely to be involved in school food poisoning (aOR= 4.439; 95% CI: 2.690,7.177; p <0.001) compared with MOE schoolchildren. Moreover, egg consumption was 4.6 times (aOR=4.627; 95% CI: 1.779,12.035; p=0.002) more likely to be associated with school food poisoning outbreaks in Terengganu in 2016 compared with rice consumption. Cross-contamination (aOR=0.445; 95% CI: 0.445,0.231; p=0.015) was less likely to be linked to school food poisoning compared with inadequate cooking and reheating. Food poisoning among schoolchildren in Terengganu has been associated with non-modifiable factors, such as school district location, and modifiable factors, such as food vehicles and critical control points. Health education on food safety, food handling, strict hygiene practice and clean canteen environment need to be strengthened.

Characterisation of IncI1 plasmids associated with change of phage type in isolates of Salmonella enterica serovar Typhimurium

BackgroundAcquisition of IncI1 plasmids by members of the Enterobacteriaceae sometimes leads to transfer of antimicrobial resistance and colicinogeny as well as change of phage type in Salmonella Typhimurium. Isolates of S. Typhimurium from a 2015 outbreak of food poisoning were found to contain an IncI1 plasmid implicated in change of phage type from PT135a to U307 not previously reported. The origin of the changes of phage type associated with this IncI1 plasmid was investigated. In addition, a comparison of its gene composition with that of IncI1 plasmids found in local isolates of S. Typhimurium typed as U307 from other times was undertaken. This comparison was extended to IncI1 plasmids in isolates of phage types PT6 and PT6 var. 1 which are thought to be associated with acquisition of IncI1 plasmids.ResultsAnalysis of IncI1 plasmids from whole genome sequencing of isolates implicated a gene coding for a 1273 amino acid protein present only in U307 isolates as the likely source of change of phage type. The IncI1 plasmids from PT6 and PT6 var. 1 isolates all had the ibfA gene present in IncI1 plasmid R64. This gene inhibits growth of bacteriophage BF23 and was therefore the possible source of change of phage type. A fuller comparison of the genetic composition of IncI1 plasmids from U307 isolates and PT6 and PT6 var. 1 isolates along with two IncI1 plasmids from S. Typhimurium isolates not showing change of phage type was undertaken. Plasmids were classified as either ‘Delta’ or ‘Col’ IncI1 plasmids according to whether genes between repZ and the rfsF site showed high identity to genes in the same location in R64 or ColIb-P9 plasmids respectively. Comparison of the tra gene sets and the pil gene sets across the range of sequenced plasmids identified Delta and Col plasmids with almost identical sequences for both sets of genes. This indicated a genetic recombination event leading to a switch between Delta and Col gene sets at the rfsF site. Comparisons of other gene sets showing significant variation among the sequenced plasmids are reported. Searches of the NCBI GenBank database using DNA and protein sequences of interest from the sequenced plasmids identified global IncI1 plasmids with extensive regions showing 99 to 100% identity to some of the plasmids sequenced in this study indicating evidence for widespread distribution of these plasmids.ConclusionTwo genes possibly associated with change of phage type were identified in IncI1 plasmids. IncI1 plasmids were classified as either ‘Delta’ or ‘Col’ plasmids and other sequences of significant variation among these plasmids were identified. This study offers a new perspective on the understanding of the gene composition of IncI1 plasmids. The sequences of newly sequenced IncI1 plasmids could be compared against the regions of significant sequence variation identified in this study to understand better their overall gene composition and relatedness to other IncI1 plasmids in the databases.

ANTIMICROBIAL ACTIVITY OF ESSENTIAL OILS OF <i>Origanum vulgare</i> AND <i>Ocimum basilicum</i> AGAINST <i>Vibrio parahaemolyticus</i> AND <i>Vibrio vulnificus</i> AND ADDITION OF THESE OILS ON <i>Mugil platanus</i> FILLETS

Species of the Vibrio genus are commonly reported as agents of food poisoning outbreaks associated with fish consumption. The objective of this study was to assess the antimicrobial activity of the essential oils of Origanum vulgare and Ocimum basilicum against Vibrio parahaemolyticus and Vibrio vulnificus, as well as to assess their addition to fillets of Mugil platanus and sensorial acceptance among consumers. The antimicrobial activity was analyzed by the disc diffusion test and minimal bactericidal concentration (MBC). M. platanus fillets, experimentally contaminated, were marinated for 24 hours in a solution containing 1.0% and 1.5% of essential oil of O. vulgare. For the sensory analysis, samples marinated in 1.5% of O. vulgare oil were prepared and offered to 100 testers. The oil of O. basilicum shows no antimicrobial activity, so its application would be ineffective; for such reason the subsequent tests were not performed. However, the essential oil of O. vulgare produced inhibition halo diameters ranging from 24.6 to 34.1 mm, on average, and the MBC ranging from 3.9% to 15.6%. When added to the product, the essential oil of O. vulgare eliminated the microorganisms that were experimentally inoculated. In the sensorial analysis, samples marinated in 1.5% of O. vulgare essential oil obtained an average of 6.82 of acceptance note among consumers.

THE IMPACT OF EDUCATION ON KNOWLEDGE, ATTITUDE AND PRACTICE OF FOOD VENDORS IN ABIA STATE NIGERIA

Educational intervention on food industry personnel on hygiene has been recommended as a means of improving food handling practices and food safety. This is because human handling errors are responsible for the major outbreaks of food poisoning and food-borne illnesses in developing and developed countries. The study aim toassess the impact of education on knowledge, attitude and practice of food vendors in study Areas in Abia State Nigeria. This study adopted a quasi-experimental study research design which involved one experimental group and one control group for the selection of the 52 food handlers in the five selected Local Government Areas in Abia State. Data were collected using a pretested semi-structured interviewer administered questionnaire and an observational checklist. Descriptive analysis was done with frequencies and summary statistics, T-test and independent sample test was computed to determine the mean difference and significant relationship of variables. Level of significance was set at 0.05 significant levels.Themean knowledge score of the control group was 4.02 ± 1.55 while the mean knowledge score of the experimental group was 7.92 ± 2.50 before the intervention. The difference between the means of the two groups was statistically significant (t=9.28; p=0.000). Also, the mean attitude score was 37.58 ± 3.31 in the control while mean attitude score was 37.79 ± 5.10 in the subjects. The difference between the groups was not statistically significant (t=0.24; p=0.813). The mean practice score was 8.21 ± 2.69 in the control group while the mean practice score was 8.73 ± 4.76 in the experimental group. The difference between the groups was not statistically significant (t=0.67; p=0.506).After the intervention, the mean knowledge score for the experimental group was 9.02 ± 1.58 while that of the control group was 5.55 ± 1.54. The difference between the group was statistically significant (t= 11.03; p=0.000). The mean attitude score for the experimental group was 40.33 ± 4.10 while that of the control group was 41.81 ± 1.963. The difference between the groups was statistically significant (t=2.26; p=0.026). Educational and training programs should be implemented to influence the food vendors’ knowledge, attitude, and practice positively.

Characteristics of Norovirus Food Poisoning Outbreaks in Korea in the 2000s

Norovirus food poisoning outbreaks in Korea (South) appeared in the 2000s and have been increasing since then. We aimed to investigate the epidemiological features of norovirus food poisoning outbreaks in Korea from 2002 to 2017, on the basis of official food poisoning statistics and publically reliable reports, and to find any associations with climate factors. Norovirus was the most common cause of food poisoning among known causative substances in Korea during the study period. More than one-third of the outbreaks occurred in group meal service facilities, including school lunch programs. A few of these facilities used groundwater contaminated with noroviruses to wash or cook food, which contributed to outbreaks. Norovirus occurrences showed strong seasonality: cold and relatively dry winter air may help norovirus to flourish. Both norovirus genotypes GI and GII that are infectious to humans were detected, with GII becoming more prevalent than GI. According to our correlation analysis in connection with climate factors, average temperatures, the highest and lowest temperatures, precipitation, the number of rain days, and humidity showed a significant negative correlation with a monthly norovirus occurrence (P < 0.05). The lowest temperature and average temperature had higher coefficients of correlation, -0.377 and -0.376, respectively. The norovirus outbreaks in Korea showed complex etiological characteristics, although more prevailed in wintertime, and are now a major public health problem. The use of groundwater in group meal service settings is a public health issue, as well as a norovirus concern; therefore, groundwater used in food service facilities and businesses should be treated for safety.

Quantitative Determination of Staphylococcus aureus Enterotoxins Types A to I and Variants in Dairy Food Products by Multiplex Immuno-LC-MS/MS.

Staphylococcal enterotoxins (SEs) are responsible for frequent food poisoning outbreaks worldwide. Specific identification of SEs is crucial for confirmation of food poisoning, tracking of the incriminated foods or food ingredients, and removal from the food chain. Here, we report on a new food testing protocol addressing the challenge of low abundance of SEs in contaminated food and high sequence heterogeneity. Multiplex ability of targeted high-resolution mass spectrometry was succesfully applied to the simultaneous and quantitative determination of the eight most frequent SEs including sequence variants. In this aim, between three and eight proteotypic peptides of each SE were selected by carefully considering amino acid variations within each type, and sequence homology between types. Quantification of trace levels of SEs directly in food samples was reached by immunoaffinity enrichment and optimized analytical conditions. The assay was validated in dairy food products with a lower limit of quantification down to 0.1 ng/g (in milk), and quantification of SEs was successfully demonstrated in real-life samples collected during staphylococcal food poisoning outbreaks. Importantly, the ability of the method to detect diverse sequence variants was also illustrated. By enabling for the first time the simultaneous quantification of the eight most frequent SEs, the new mass spectrometry-based assay would facilitate the laboratory confirmation of positive samples in situation of food poisoning outbreaks.

Aptamer-immobilized Gold Nanoparticles Enable Facile and On-site Detection of Staphylococcus aureus

Staphylococcus aureus causes numerous illnesses and national loss in many countries. Therefore, to prevent food poisoning outbreaks, a rapid and straightforward on-site detection method is required without special skills or equipment. Here, we used aptamer-immobilized gold nanoparticles (aiGNPs) for the on-site colorimetric S. aureus detection. For the rapid and facile detection of S. aureus, the SA61 aptamer hybridized with thiol-modified adaptors conjugated onto the GNP surface of approximately 13 nm diameter. The synthesis of GNPs was confirmed using a transmission electron microscopy and energy dispersive spectroscopy. Images using a scanning electron microscope showed attachment of aiGNPs to S. aureus. After 30-min incubation and 20-min centrifugation, the red pellet was specifically observed with the sensitivity of OD600 0.050 equivalent to 7.5 × 106 cells/mL. Besides, aiGNPs could accurately detect S. aureus with a detection limit of OD600 0.10 equivalent to 1.5 × 107 cells/mL even in the mixed sample with Escherichia coli. Quantitative analysis was performed between relative area and cell concentration. Because this method enables fast and specific S. aureus detection without special skills or expensive equipment, aiGNPs could enable a rapid and effective on-site detection of S. aureus to prevent pathogenic outbreaks.

Molecular characterization and in vivo pathogenicity study of Listeria monocytogenes isolated from fresh and frozen local and imported fish in Jordan.

Background:Listeria monocytogenes (L. monocytogenes) is a serious zoonotic and food transmitted human pathogen causing meningitis and abortions. Several outbreaks of listeriosis have been associated with the consumption of ready-to-eat food products; dairy, meat, fish, and contaminated fruits and vegetables worldwide.Aim:This study was designed to detect and characterize L. monocytogenes isolated from local and imported fish in Jordan. Methods:A total of 170 fish (70 local and 100 imported), of which 140 fresh and 30 frozen samples were used in this study. Listeria monocytogenes was cultured and initially identified using conventional microbiological methods. For confirmation and serotyping of the L. monocytogenes isolates, PCR techniques were used. Using oral and intraperitoneal administration, mice were used to determine the pathogenicity and LD50 of the isolated L. monocytogenes. Results:A total of 72 Listeria spp. isolates were cultured from fish. Of those, 24 were positively identified as L. monocytogenes. Other strains of Listeria spp. were L. ivanovii (21), L. innocua (11), and L. grayi (16). Serotyping of the L. monocytogenes indicated that 14 isolates belonged to the 1/2b, 3b serotypes whereas 10 isolates belonged to the 4a and 4c serotypes. All isolates were virulent to mice with an LD50 dose ranging from 3 × 1010 CFU/ml to 3 × 107.5 CFU/ml. All the virulent isolates belonged to the serotype 1/2b. Histopathologically, dead mice showed multiple necrotic lesions in the liver and spleen.Conclusion:Results of this study showed the presence of potentially pathogenic L. monocytogenes in fresh and frozen, local, and imported fish in Jordan. Strict monitoring and quality control regulatory measures must be adopted to prevent future outbreaks of food poisoning associated with fish consumption.

Acute gastroenteritis outbreak in a school associated with religious ceremony in Mirzapur District, Uttar Pradesh, India.

A suspected food-poisoning outbreak occurred in a residential school in Mirzapur, India, in February, 2017. We investigated the outbreak to find out the epidemiology and to identify the risk factors. A descriptive study followed by retrospective-cohort study was done to investigate the outbreak. Cases (defined as ≥3 or more loose stools in 24 h, abdominal pain, or vomiting with onset between February 1 and 4, 2017) were searched by reviewing sick/patient registers from school and nearby health facilities. Cases were also searched through active surveillance by visiting school hostels. Stool samples were sent for microbiological testing. Food sources and food handlers were also assessed. Among 468 students, 204 cases were identified (44% attack rate) without any mortality. The median age was found to be 14 years (range: 10-18 years) and 59% were male. Relative risk with consumption of curd, apple, and panjiri (sweetened wheat flour) was found to be 15.4, 2.5, and 3.7, respectively. All these three food items were served as prasad, a religious offering. Only consumption of sweetened curd (adjusted odds ratio = 36.1, 95% confidence interval = 12.1-107.8) was significantly associated with gastroenteritis. No microorganism was isolated from two tested stool samples. Curd from the vendor was prepared from nonpasteurized milk. There were no illnesses among food-handlers. This outbreak of acute gastroenteritis in a residential school was associated with consumption of curd, likely contaminated with preformed toxins. We recommend implementation of the food safety and standards authority of India regulations.

In-vitro Antimicrobial Activity of Essential Oils and Spices Powder of some Medicinal PlantsAgainst Bacillus Species Isolated from Raw and Processed Meat.

Background and AimBacillus species are widely distributed microorganisms in nature that are responsible for outbreaks of food poisoning and a common cause of food spoilage. This study aimed to isolate and identify foodborne Bacillus species from meat and to determine the antimicrobial activities of commercial essential oils and spices powder extracted from certain medicinal plants.MethodsSixty meat samples were collected in Assiut city and subdivided into raw meat and processed meat. Bacillus spp were isolated and identified according to their cultural characters, biochemical reactions, serological typing, and 16S rRNA gene sequencing. The antibacterial activity of essential oils and spices powder was measured by using well-diffusion and microbial count techniques.ResultsThe prevalence of Bacillus spp. in the examined raw meat samples and processed meat samples was 13.34%, and 26.67%, respectively. There was a marked decrease in the total Bacillus species count after treatment of minced beef with essential oils and spices powder compared to the untreated one. Black seed oil was the most potent antibacterial essential oil among the tested oils present in this study.ConclusionEssential oils and spices powder of certain medicinal plants (cumin: Cuminum cyminum, black seeds: Nigella sativa, cloves: Syzygium aromaicum, cinnamon: Cinnamomum zeylanicum, and Marjoram: Origanum majorana) have a potential in vitro antimicrobial activity against Bacillus spp. Furthermore, Nigella sativa oil exhibited the most potent antibacterial activity against Bacillus spp.

Genome persistence & survival of Clostridium perfringens from ichthyofauna of dal lake Himalaya-A possible future public health hazard

Background: Clostridium perfringens is one of the most prolific toxin-producing bacteria, an indicator of fecal contamination in aquatic habitats. This bacterium is not known to cause any disease in fish but its importance in fish is primarily due to the health hazards to humans, as C. perfringens has been found to be the causative agent of many outbreaks of food poisoning associated with the consumption of fish and its products. Aquatic resources of Kashmir are in a serious state of eutrophication-particularly cultural, more pronounced in Dal Lake, which has witnessed an increase in food borne pathogens. We aimed to investigate the presence of different toxinotypes of C. perfringens in commonly consumed fishes of Kashmir. Methods and materials: Collection of samples. Isolation and identification by culture & staining. DNA extraction and PCR using species-specific 16S rRNA gene amplification, The toxinotyping of C. perfringens isolates by multiplex-PCR targeting six toxin genes (cpa, cpb, ɛtx, ιtx, cpb2 and cpe). Phylogenetic analysis and antibiotic sensitivity tests. Results: All the 45 isolates from water and 37 isolates from fish (21 from scale-carp and 16 from snow-trout) were found to carry cpa gene alone as a major toxin gene and thus were designated as toxinotype A. None of the isolates carried cpb, ɛtx, ιtx, cpb2 or cpe genes indicating the absence of C. perfringens toxinotypes B, C, D or E in the water and fish samples of the Dal Lake. The prevalence of C. perfringens was slightly higher in scale-carps (35%) compared to snow-trouts (26.6%).Phylogenetic analysis of the cpa toxin genes of C. perfringens revealed 95% to 98% homology with corresponding GenBank published sequences and close relationship with corresponding AA sequences of C. perfringens strains reported from India, Egypt and China. Conclusion: Presence of C. perfringens toxinotype A in fish for the first time in the Dal Lake of the Kashmir valley and implied that fish may be a possible source of C. perfringens type A intoxication to humans through food chain posing a serious public health concern.The antibiogram pattern of the C. perfringens type A isolates revealed a higher antimicrobial resistance to amikacin, ceftriaxone, metronidazole, norfloxacin and tetracycline.

Clostridium perfringens in Meat and Meat Products: A minireview on the Incidence, Public Health Significance, and the Effects of Essential Oils

Anaerobic spore formers, particularly Clostridium perfringens, are an important cause of food poisoning outbreaks worldwide, which is mainly related to the consumption of contaminated meat and its products. C. perfringens is a commensal inhabitant in the intestinal tract of animals and humans. C. perfringens is a ubiquitous Gram positive, anaerobic spore former which produces many toxins and is related to various diseases in humans such as food poisoning, necrotic enteritis, diarrhea, enterotoxemia and gangrene. The occurrence of multidrug resistant C. perfringens in meat and its products raises public health concerns. The ability of C. perfringens to grow as a biofilm favors its survival in the environment. Therefore, the bacteriological quality and safety of commercially processed meat products is important for the consumers and public health worldwide. The prevention of growth of C. perfringens is best achieved by following the food service practices by addition of some natural essential oils such as Thyme (Thymus vulgaris) and Marjoram (Origanum majorana) essential oil.

Multiplex Immunoassay Techniques for On-Site Detection of Security Sensitive Toxins.

Biological toxins are a heterogeneous group of high molecular as well as low molecular weight toxins produced by living organisms. Due to their physical and logistical properties, biological toxins are very attractive to terrorists for use in acts of bioterrorism. Therefore, among the group of biological toxins, several are categorized as security relevant, e.g., botulinum neurotoxins, staphylococcal enterotoxins, abrin, ricin or saxitoxin. Additionally, several security sensitive toxins also play a major role in natural food poisoning outbreaks. For a prompt response to a potential bioterrorist attack using biological toxins, first responders need reliable, easy-to-use and highly sensitive methodologies for on-site detection of the causative agent. Therefore, the aim of this review is to present on-site immunoassay platforms for multiplex detection of biological toxins. Furthermore, we introduce several commercially available detection technologies specialized for mobile or on-site identification of security sensitive toxins.

Toxin Production and Resistance of Staphylococcus Species Isolated from Fermented Artisanal Dairy Products in Benin.

Staphylococcus species are considered as one of the major pathogens causing outbreaks of food poisoning. The aim of this work was to assess the toxinogenic and antibiotic susceptibility profiles of the strains of Staphylococcus spp isolated from three types of fermented dairy products (yoghourt, millet dêguê, and couscous dêguê). The isolation of the Staphylococcus strains was performed on selective media, and their identification was done using biochemical and molecular methods. The susceptibility at 15 antibiotics tested was assessed using the disc diffusion method. The immunodiffusion method was used to evaluate the toxin (luk-E/D, luk-S/F, ETA, and ETB) production. Biofilm formation was qualitatively researched on microplates. Less than half (42.77%) of the collected samples were contaminated with Staphylococcus spp. The yoghourt and millet dêguê samples collected in the afternoon were more contaminated than those collected in the morning. The S. aureus, S. capitis, and S. xylosus strains, respectively, were the most present. S. aureus was the only coagulase-positive species identified in our samples. The highest resistance to antibiotics was observed with penicillin (100%) irrespective of the nature of the sample. S. aureus strains were highly (71.4%) resistant to methicillin. The S. aureus strains were the most biofilm-forming (27.6%), followed by S. capitis strains. Panton and Valentine's leukocidin (luk-S/F) was produced by only S. aureus strains at a rate of 8.33%. Only coagulase-negative Staphylococcus (CNS) produced Luk-E/D. The high rates of Staphylococci contamination indicate bad hygiene quality during the production and distribution of dairy products. It is, therefore, necessary to improve the quality of fermented milk products.

Establishment of a Novel Molecular Detection Method for Sarcocystis in Venison.

Recently, horse meat (basashi) contaminated with Sarcocystis spp. caused food poisoning in Japan. An official detection method provided by the Ministry of Health, Labour and Welfare (MHLW), Japan, was designed to detect Sarcocystis fayeri to diagnose and control outbreaks of basashi food poisoning. In 2011, Sarcocystis-contaminated venison also caused food poisoning. However, the official MHLW detection method was not adequate for detecting Sarcocystis spp. in venison. In this study, we established a novel PCR-based detection method that amplifies 18S rRNA gene based on the conserved region of the sequence in 32 species of Sarcocystis for screening and quantification. Fifty venison samples from three areas in Hokkaido were examined by the MHLW method and the novel detection method. All samples were Sarcocystis spp.-positive. A sequence analysis indicated the presence of a species of Sarcocystis specific to sika deer (Cervus nippon), and not to horses. Another primer pair was designed for a quantitative real-time PCR assay to determine the copy number of the Sarcocystis-18S rRNA gene in parasitized venison. The melting curve analysis revealed high specificity of this assay. The calculated curve demonstrated that this quantitative PCR assay showed R2 value of 0.993 with 10-106 copies. Using this quantitative real-time PCR assay, the gene copy numbers were determined in 50 venison samples. The copy numbers of each sample ranged from 104 to 107 per gram. The copy numbers differed according to the area in Hokkaido. This indicates that the density of Sarcocystis spp. that infect Sika deer in Hokkaido is affected by the area. The novel screening and quantitative PCR method for Sarcocystis in venison was useful for collecting epidemiological information on Sarcocystis in wild Japanese sika deer, which will contribute to improve the safety of venison products in Japan.

Thermosonication pretreatment enhances the killing of germinated Bacillus spores adhered to stainless steel surface

The retention of bacterial spores on food processing stainless steel (SS) surfaces can be a source of cross-contamination from food contact surfaces to food products. This study aimed to develop an effective strategy to inactivate spores of Bacillus subtilis and Bacillus cereus on SS by stimulating spore germination and killing germinated spores with a combination of thermosonication (TS) pretreatment and other subsequent treatments (nisin/thyme essential oil (TEO)/UV). A mixture of l-asparagine, fructose, glucose, and potassium chloride (AGFK) initiated the maximum germination of spores at 37 °C. Notably, the implementation of a germination-inducing step did increase the susceptibility of spores to environmental stress. Moreover, TS pretreatment enhanced the efficacy of subsequent inactivation treatments (UV irradiation), resulting in an additional 2.74 to 3.78 log reductions in germinated spores of both Bacillus suspension. Whereas the sporicidal activities of subsequent nisin/TEO incubation were not greatly increased by TS pretreatments. TS pretreatment still increased sporicidal activity of UV irradiation against both Bacillus spores attached to SS coupons, even though adhered spores germinated not fast as those in suspension. Collectively, the findings from this study could be beneficial for reducing contamination of Bacillus spores on food contact surface and the potential risks of food poisoning outbreaks.

Выделение и описание Staphylococcus aureus, вызвавшей две широкомасштабные вспышки пищевых отравлений во Вьетнаме

In Vietnam and around the world, Staphylococcus aureus remains a major hazard of food safety and food poisoning. S. aureus is present in many places and easily contaminates food production during processing chains. In this study, we successfully isolated S. aureus strains from suspected samples of two food borne poisoning outbreaks in Ha Giang and Vinh Phuc in 2017 and 2018, respectively. The collected samples were examined for presence of staphylococcal enterotoxins (SEs) by using 3MTMTECRATM Staph Enterotoxin kit, from there all the samples were positive with SEs. Different strains of S. aureus were isolated and then confirmed by MALDI-TOF technique. Those strains then were stored in Brain heart solution with 15% glycerol until further analysis. Our results identified three STs, ST96, ST88 (spa type t7558), and ST72 (spa type t3092), were responsible for two outbreaks. Two virulence genes detected from the above strains were sea and sec. Furthermore, these strains are test for antibiotic resistance susceptibility with commonly antibiotics. Penicillin are found to be resisted by all three STs, in particularly, ST96 and ST88 are both resistant to erythromycin while ST72 is resistant to gentamicin. Taken together, our study highlights the usefulness of molecular characterization to study and monitor bacterial pathogens associated with food poisoning outbreaks in Vietnam.

Isolation and characterization of staphylococcus aureus from two large-scale food poisoning outbreaks in Vietnam

In Vietnam and around the world, Staphylococcus aureus remains a major hazard of food safety and food poisoning. S. aureus is present in many places and easily contaminates food production during processing chains. In this study, we successfully isolated S. aureus strains from suspected samples of two food borne poisoning outbreaks in Ha Giang and Vinh Phuc in 2017 and 2018, respectively. The collected samples were examined for presence of staphylococcal enterotoxins (SEs) by using 3MTMTECRATM Staph Enterotoxin kit, from there all the samples were positive with SEs. Different strains of S. aureus were isolated and then confirmed by MALDI-TOF technique. Those strains then were stored in Brain heart solution with 15% glycerol until further analysis. Our results identified three STs, ST96, ST88 (spa type t7558), and ST72 (spa type t3092), were responsible for two outbreaks. Two virulence genes detected from the above strains were sea and sec. Furthermore, these strains are test for antibiotic resistance susceptibility with commonly antibiotics. Penicillin are found to be resisted by all three STs, in particularly, ST96 and ST88 are both resistant to erythromycin while ST72 is resistant to gentamicin. Taken together, our study highlights the usefulness of molecular characterization to study and monitor bacterial pathogens associated with food poisoning outbreaks in Vietnam.

Staphylococcus aureus Exotoxins and Their Detection in the Dairy Industry and Mastitis.

Staphylococcus aureus constitutes a major food-borne pathogen, as well as one of the main causative agents of mastitis in dairy ruminants. This pathogen can produce a variety of extracellular toxins; these include the shock syndrome toxin 1 (TSST-1), exfoliative toxins, staphylococcal enterotoxins (SE), hemolysins, and leukocidins. S. aureus expresses many virulence proteins, involved in evading the host defenses, hence facilitating microbial colonization of the mammary glands of the animals. In addition, S. aureus exotoxins play a role in the development of both skin infections and mastitis. Indeed, if these toxins remain in dairy products for human consumption, they can cause staphylococcal food poisoning (SFP) outbreaks. As a result, there is a need for procedures to identify the presence of exotoxins in human food, and the methods used must be fast, sensitive, reliable, and accurate. It is also essential to determine the best medical therapy for human patients suffering from S. aureus infections, as well as establishing the relevant veterinary treatment for infected ruminants, to avoid economic losses in the dairy industry. This review summarizes the role of S. aureus toxins in the development of mastitis in ruminants, their negative effects in the food and dairy industries, and the different methods used for the identification of these toxins in food destined for human consumption.

Prediction of detection time of staphylococcal enterotoxin A formed in hydrated batter mix

Staphylococcus aureus food poisoning is caused by the ingestion of staphylococcal enterotoxin (SE) produced in foods and SE type A (SEA) is the most common among many types. While SEA formation in hydrated batter mix can be a potential hazard in the production processes of foods, no information is available. Therefore, the growth kinetics of S. aureus and subsequent SEA formation in hydrated batter mix during storage were studied to estimate the detection time (DT) of SEA. At 30 °C and with different inocula (3–5 log CFU/g), SEA was detected when the population of S. aureus reached 5.5–5.9 log CFU/g in the samples. With an inoculum of 4 log CFU/g and isothermal storage between 14 and 34 °C, SEA was detected when the population reached approximately 6 log CFU/g. Therefore, the time to 6 log CFU/g was chosen to as the DT of SEA in the samples. With a kinetic model predicting the growth of S. aureus in hydrated batter mix, the DTs of SEA stored under both changing and constant temperatures were successfully predicted. These results suggested that the present kinetic model could predict the DT of SEA in hydrated batter mix during storage. Prediction of DT of SEA in batter mix would be useful information to prevent the outbreaks of staphylococcal food poisoning.