Foodborne Intoxication Research Articles

Draft Genome Sequences of Two Clostridium botulinum Group II Strains Carrying Phage-Like Plasmids.

ABSTRACTClostridium botulinum is responsible for botulism, a potentially lethal foodborne intoxication. Here, we report the draft genome sequences of C. botulinum group II strains 202F (serotype F) and Hazen (serotype E). The genomes share many similarities, including multiple mobile genetic elements.

Lichenysin Production by Bacillus licheniformis Food Isolates and Toxicity to Human Cells.

Bacillus licheniformis can cause foodborne intoxication due to the production of the surfactant lichenysin. The aim of this study was to measure the production of lichenysin by food isolates of B. licheniformis in LB medium and skimmed milk and its cytotoxicity for intestinal cells. Out of 11 B. licheniformis isolates tested, most showed robust growth in high salt (1M NaCl), 4% ethanol, at 37 or 55°C, and aerobic and anaerobic conditions. All strains produced lichenysin (in varying amounts), but not all strains were hemolytic. Production of this stable compound by selected strains (high producers B4094 and B4123, and type strain DSM13T) was subsequently determined using LB medium and milk, at 37 and 55°C. Lichenysin production in LB broth and milk was not detected at cell densities < 5 log10 CFU/ml. The highest concentrations were found in the stationary phase of growth. Total production of lichenysin was 4–20 times lower in milk than in LB broth (maximum 36 μg/ml), and ∼10 times lower in the biomass obtained from milk agar than LB agar. Under all conditions tested, strain B4094 consistently yielded the highest amounts. Besides strain variation and medium composition, temperature also had an effect on lichenysin production, with twofold lower amounts of lichenysin produced at 55°C than at 37°C. All three strains produced lichenysin A with varying acyl chain lengths (C11–C18). The relative abundance of the C14 variant was highest in milk and the C15 variant highest in LB. The concentration of lichenysin needed to reduce cell viability by 50% (IC50) was 16.6 μg/ml for Caco-2 human intestinal epithelial cells and 16.8 μg/ml for pig ileum organoids. Taken together, the presence of low levels (<5 log10 CFU/ml) of B. licheniformis in foods is unlikely to pose a foodborne hazard related to lichenysin production. However, depending on the strain present, the composition, and storage condition of the food, a risk of foodborne intoxication may arise if growth to high levels is supported and such product is ingested.

Staphylococcus Aureus: A Major Pathogen of Food Poisoning

Food poisoning that involves multiple etiologies is reported from developing as well as developed nations.Among the microbial causes, Staphylococcus aureus is a major pathogen of food poisoning that can occur in sporadic and epidemic form. It may cause life-threatening infections in children, the elderly, and immunocompromised persons. Staphylococcal food poisoning is responsible for 241,000 cases in the United States annually. A variety of foods, such as meat and meat products, milk and milk products, poultry, egg, fish, vegetable salad, and cream-filled pastries are implicated as a source of staphylococcal food poisoning. Unhygienic handling of food is considered an important source of S. aureus contamination. Enterotoxins produced by S. aureus play a vital role in the pathogenesis of staphylococcal food poisoning. Due to ingestion of preformed toxins in the food, the incubation period of staphylococcal food poisoning is very short. The main symptoms of staphylococcal food poisoning are nausea, vomiting, abdominal cramps, and diarrhea. The detection of enterotoxin is highly imperative for the investigation of staphylococcal food poisoning. Most of the patients do not require any treatment as the disease is generally self-limiting and normally resolves within 24–48 h after onset. Hygienic production of food and education of food handlers about the principles of food hygiene are the main strategies for the prevention of staphylococcal food poisoning. The objective of this communication is to delineate the growing significance of S. aureus as a leading cause of foodborne intoxication.

Differences in caecal microbiota composition and Salmonella carriage between experimentally infected inbred lines of chickens

BackgroundSalmonella Enteritidis (SE) is one of the major causes of human foodborne intoxication resulting from consumption of contaminated poultry products. Genetic selection of animals that are more resistant to Salmonella carriage and modulation of the gut microbiota are two promising ways to decrease individual Salmonella carriage. The aims of this study were to identify the main genetic and microbial factors that control the level of Salmonella carriage in chickens (Gallus gallus) under controlled experimental conditions. Two-hundred and forty animals from the White Leghorn inbred lines N and 61 were infected by SE at 7 days of age. After infection, animals were kept in isolators to reduce recontamination of birds by Salmonella. Caecal contents were sampled at 12 days post-infection and used for DNA extraction. Microbiota DNA was used to measure individual counts of SE by digital PCR and to determine the bacterial taxonomic composition, using a 16S rRNA gene high-throughput sequencing approach.ResultsOur results confirmed that the N line is more resistant to Salmonella carriage than the 61 line, and that intra-line variability is higher for the 61 line. Furthermore, the 16S analysis showed strong significant differences in microbiota taxonomic composition between the two lines. Among the 617 operational taxonomic units (OTU) observed, more than 390 were differentially abundant between the two lines. Furthermore, within the 61 line, we found a difference in the microbiota taxonomic composition between the high and low Salmonella carriers, with 39 differentially abundant OTU. Using metagenome functional prediction based on 16S data, several metabolic pathways that are potentially associated to microbiota taxonomic differences (e.g. short chain fatty acids pathways) were identified between high and low carriers.ConclusionsOverall, our findings demonstrate that the caecal microbiota composition differs between genetic lines of chickens. This could be one of the reasons why the investigated lines differed in Salmonella carriage levels under experimental infection conditions.

Antifungal Preservation of Food by Lactic Acid Bacteria.

Fungal growth and consequent mycotoxin release in food and feed threatens human health, which might even, in acute cases, lead to death. Control and prevention of foodborne poisoning is a major task of public health that will be faced in the 21st century. Nowadays, consumers increasingly demand healthier and more natural food with minimal use of chemical preservatives, whose negative effects on human health are well known. Biopreservation is among the safest and most reliable methods for inhibiting fungi in food. Lactic acid bacteria (LAB) are of great interest as biological additives in food owing to their Generally Recognized as Safe (GRAS) classification and probiotic properties. LAB produce bioactive compounds such as reuterin, cyclic peptides, fatty acids, etc., with antifungal properties. This review highlights the great potential of LAB as biopreservatives by summarizing various reported antifungal activities/metabolites of LAB against fungal growth into foods. In the end, it provides profound insight into the possibilities and different factors to be considered in the application of LAB in different foods as well as enhancing their efficiency in biodetoxification and biopreservative activities.

Detection and Determination of Staphylococcus aureus in Camel Milk and Associated Factors in Fedis, Eastern Hararghe, Ethiopia.

Background:Camel milk is the key food for pastoralists in the arid and semi-arid areas of the eastern lowlands of Ethiopia. Unless it is handled under good hygienic conditions, milk can be a good medium for bacterial growth and can lead to foodborne diseases caused by various pathogenic microorganisms, such as Staphylococcus aureus. The current study was aimed to determine the prevalence of Staphylococcus aureus in raw camel milk and associated factors in Fedis, Eastern Ethiopia.Methods:A cross-sectional study was conducted from December 2, 2018 to May 26, 2019 in Fedis, Eastern Hararghe, Ethiopia. The questionnaire was used to determine the hygienic practices of camel milkers and sellers. Laboratory analysis was conducted to determine the level of Staphylococcus aureus. A total of 156 (78 from households and 78 from selling sites) milk samples were collected randomly from selected camel herd owners and selling sites for the isolation and enumeration of Staphylococcus aureus. Data analysis was carried out using SPSS software version 22.0. Finally, Chi-square and Fisher’s exact tests were used to analyze the data. A P-value of .05 was considered as the cut-off point for statistical significance.Results:A total of 156 samples, including 78 samples of raw milk from the households and 78 samples from the market were purchased to determine Staphylococcus aureus. Out of 156 samples, Staphylococcus aureus was detected in 60 (38.5%) samples, of which 27 (34.6%) and 33 (42.3%) were among those collected from household and market, respectively. The overall mean Staphylococcus aureus count was 4.83 log CFU/mL, with household and market samples accounted for 2.76 and 5.08 log CFU/mL, respectively. Furthermore, 23 (38.3%) of the samples were contaminated with Staphylococcus aureus beyond the recommended level (4-5 log CFU/mL). There was a statistically significant association (P-value of <.05) between the prevalence of Staphylococcus aureus and other variables such as age of the camel, parity, lactation stages, and sources of milk.Conclusion:More than one-third of milk samples were contaminated with Staphylococcus aureus at levels higher than the maximum permitted level. The findings of the current study suggests that there is a potential risk of foodborne infection and intoxication. Therefore, implementation of adequate hygiene and safety practices is very important to prevent the consumption of contaminated fruit juices, which leads to foodborne illness.

Evaluation of the Effect of Wastewater Irrigation on the Microbiological Quality of Vegetables in Northeast Ethiopia: Implication for Food-Borne Infection and Intoxications.

background:Cultivation of vegetables using untreated wastewater is a common phenomenon in many drought-prone areas of the world. Consumption of such microbiologically unsafe vegetable increase the risk of food-borne diseases. As a result, evaluating the effect of wastewater irrigation on the microbiological quality of vegetables would be beneficial to consumers’ health.method:A total of 192 vegetable samples (lettuce, cabbage, carrot, and tomato) and 64 irrigation water samples were collected and analyzed for total bacteria and coliform count using a standardized protocol over a 4 month period. One-way analysis of variance and Pearson correlation coefficient was used to analyze the data. Statistical significance was defined at a P-value of less than 0.05.result:Carrots were the least polluted vegetable, according to the study, while cabbage had the highest contamination levels. The mean bacterial count among the vegetables differs significantly (P < 0.05). The fecal coliform counts of the irrigation wastewater exceed the international wastewater irrigation standards. The mean microbial count between vegetables and water samples showed a significant positive relationship (P < 0.05). All of the analyzed vegetable samples were of borderline microbial quality for fecal coliform bacteria.conclusion:Irrigation wastewater has a low microbiological quality, which significantly contributes to the contamination of vegetables grown on it.recommendation:Measures should be taken to improve the microbial quality of wastewater as well as the quality of vegetables grown in order to protect consumers’ health from food-borne diseases.

Evaluation of Staphylococcus aureus growth and staphylococcal enterotoxin production in delicatessen and fine bakery products

Staphylococcal food poisoning is one of the most prevalent causes of foodborne intoxication worldwide. Sandwiches and desserts are susceptible to contamination by S. aureus due to the high proportion of manual work during their production. Our study aimed to evaluate the impact of storage conditions on staphylococcal enterotoxin production in sandwiches and buttercream puffs. Foods were inoculated with different S. aureus strains capable of producing type A, B, and C staphylococcal enterotoxins and incubated at 15, 25, and 30 °C. During the storage, samples were analysed for S. aureus counts and for staphylococcal enterotoxins. An enzyme-linked fluorescence assay was used to detect staphylococcal enterotoxins. The influence of inappropriate storage on S. aureus growth and staphylococcal enterotoxin production was evaluated. No staphylococcal enterotoxins were detected in sandwiches stored for 72 h at any of the tested temperatures. In buttercream puffs, enterotoxins type A, B, and C were detected within 24 h of storage at 25 °C.

Prevalence, Enterotoxigenic Potential and Antimicrobial Resistance of Staphylococcus aureus and Methicillin-Resistant Staphylococcus aureus (MRSA) Isolated from Algerian Ready to Eat Foods.

Staphylococcus aureus causes a foodborne intoxication due to the production of enterotoxins and shows antimicrobial resistance, as in the case of methicillin-resistant strains (MRSA). Herein, we analyzed 207 ready-to-eat foods collected in Algeria, reporting a S. aureus prevalence of 23.2% (48/207) and respective loads of coagulase positive staphylococci (CPS) ranging from 1.00 ± 0.5 to 5.11 ± 0.24 Log CFU/g. The 48 S. aureus isolates were widely characterized by staphylococcal enterotoxin gene (SEg)-typing and 16S-23S rDNA intergenic spacer region (ISR)-PCR, as well as by detecting tst and mecA genes, genetic determinants of toxic shock syndrome toxin-1 and methicillin resistance, respectively. We found that the S. aureus isolates belonged to seven different SEg-types harboring the following combinations of genes: (1) selW, selX; (2) egc (seG, seI, seM, seN, seO), selW, selX; (3) seA, seH, seK, seQ, selW, selX; (4) seB, selW, selX; (5) seD, selJ, seR, selW, selX; (6) seH, selW, selX, selY; and (7) seA, egc, selW, selX, while among these, 2.1% and 4.2% were tst- and mecA- (staphylococcal chromosomal cassette mec-type IV) positive, respectively. Selected strains belonging to the 12 detected ISR-types were resistant towards antimicrobials including benzylpenicillin, ofloxacin, erythromycin, lincomycin, tetracyclin, kanamycin, oxacillin, and cefoxitin; 8.3% (1/12) were confirmed as MRSA and 16.7% (2/12) were multidrug resistant. The present study shows the heterogeneity of the S. aureus population in Algerian ready-to-eat foods as for their toxigenic potential and antimicrobial resistance, shedding the light on the quality and safety related to the consume of ready-to-eat foods in Algeria.

Naira note: Potential Environmental Material for Transmitting Bacterial Pathogens among Food Dealers in Umuahia, Nigeria

Inanimate objects can serve as environmental vehicles for transmitting pathogenic bacteria among individuals in the population. Our study revealed that of the 72 naira notes examined, 58 samples representing 80.6% had bacterial contaminants. The bacterial isolates were Staphylococcus aureus (70.8%), Salmonella spp. (51.4%), Escherichia coli (44.4%), Shigella spp. (22.2%), Pseudomonas aeruginosa. (18.1%), and Proteus spp. (1.4%). The naira notes examined were all obtained from food dealers particularly fish sellers, food vendors, and meat sellers. The presence of these bacterial pathogens on naira notes handled by those food dealers is an important public health hazard as they can contaminate food leading to foodborne diseases and intoxications. Our study found that lower denominations of currency notes (naira), were mostly contaminated by these pathogens and this could be as a result of their frequent use in daily transactions.

Attempts to Improve Antimicrobial Efficiency by Mixed-Lactobacillus Extracts as Crude or Nano-formulated Against Pathogenic and Food Spoilage Bacteria, Molds and Yeasts

Over the world, there are millions of disease cases, in addition to thousands of deaths due to food-based outbreaks every year. In order to diminish the risk of foodborne infection and intoxications and control microbial food spoilage, there is a great need to improve modes of food preservation. As well-known, nature-dependent preservation enables consumers to keep their safety while eating highly qualified food. This work aims to enhance the safety and quality of common popular food products by introducing new preservative applications suggestions. The idea is to use different lactobacilli-based fermentations; in single or mixed-status and study the obtained extracts to evaluate their influence to manage microbial contamination of food. A set of five Lactobacillus strains was utilized by this study, methanol extract of cold acetone precipitate, Diethyl ether extract, and both were tested as crude or Nano-formulated against common microbial pathogens and food spoilers. Methanol extract of all lactobacillus strains shows antibacterial-specific activity with inhibition zone ranging from 7 mm in the case of Lactobacillus rhamnosus against Salmonella enterica, to 24 mm in the case of Lactobacillus helveticus against Escherichia coli. Diethyl ether extracts based on Lactobacillus helveticus and Lactobacillus plantarum show a considerable inhibition to all utilized microbial concerns, including Saccharomyces cerviceae. Upon estimating three forms of mixed-Lactobacillus that are based on Lactobacillus helveticus (h), Lactobacillus plantarum (p), and Lactobacillus rhamnosus GG (G), the ph-dependant combination showed uprising inhibition that reached maximally 58% over that of single Lactobacilli. Nano formulation of mixed-based total extracts maximally upraised the inhibition to 39%, 32%, and 100% against gram-positive, gram-negative, and the fungus; Penicillium chrysogenum, respectively.

Investigation of Escherichia coli O157:H7 Survival and Interaction with Meal Components during Gastrointestinal Digestion.

Escherichia coli O157:H7 is responsible for foodborne poisoning, incriminating contaminated animal food and especially beef meat. This species can survive in the digestive tract, but, up to now, very few studies have considered its survival during the gastrointestinal digestion of meat. The present study aimed to investigate the survival of the pathogenic strain E. coli O157:H7 CM454 during the gastrointestinal digestion of ground beef meat and its interactions with meal components using a semidynamic digestive model. The CM454 strain in meat survived throughout digestion despite acidic pH (pH 2) and the presence of bile salts. The addition of nitrite and ascorbate in the digestion medium led to a decrease in strain survival. During digestion, a release of free iron was observed, which was accentuated in the presence of the CM454 strain. In addition, the strain modified the Fe2+/Fe3+ ratio, in favor of Fe2+ compared to the noninoculated meat sample. In the presence of nitrite, nitroso compounds such as nitrosamines, nitrosothiols, and nitrosylheme were formed. E. coli O157:H7 CM454 had no impact on N-nitrosation but seemed to decrease S-nitrosation and nitrosylation.

Detection of Bacterial Pathogens in Ready-To-Eat Foods: Potential Public Health Hazard

The right to obtain safe food is one of the most vital and fundamental human rights that must not be compromised or neglected; this is important because foodborne diseases can lead to prolonged disability and even death. Our study examined 28 samples of ready-to-eat foods, of which 27 samples (96.4%), contained bacterial contaminants. The bacterial pathogens isolated include Escherichia coli (50%), Salmonella spp (75%) and Staphylococcus aureus (85.7%). All the samples of jollof rice (100%), bean porride (100%) and eba (100%) were contaminated while 85.7% of egusi soup samples contained bacterial contaminants. The presence of these bacterial pathogens in the ready-to-eat foods poses huge risk to public health. It calls for immediate and sustainable action to prevent the possibility of foodborne disease out-break and intoxication capable of harming public health and socio-economic development.

Molecular Characterization of Staphylococcus aureus Isolated from Human and Food Samples in Northern Algeria.

Staphylococcus aureus is a commensal resident of the skin and nasal cavities of humans and can cause various infections. Some toxigenic strains can contaminate food matrices and cause foodborne intoxications. The present study aimed to provide relevant information (clonal complex lineages, agr types, virulence and antimicrobial resistance-associated genes) based on DNA microarray analyses as well as the origins and dissemination of several circulating clones of 60 Staphylococcus aureus isolated from food matrices (n = 24), clinical samples (n = 20), and nasal carriers (n = 16) in northern Algeria. Staphylococcus aureus were genotyped into 14 different clonal complexes. Out of 60 S. aureus, 13 and 10 isolates belonged to CC1-MSSA and CC97-MSSA, respectively. The CC 80-MRSA-IV was the predominant S. aureus strain in clinical isolates. The accessory gene regulator allele agr group III was mainly found among clinical isolates (70.4%). Panton–Valentine leukocidin genes lukF/lukS-PV were detected in 13.3% of isolates that all belonged to CC80-MRSA. The lukF/S-hlg, hlgA, and hla genes encoding for hemolysins and leucocidin components were detected in all Staphylococcus aureus isolates. Clinical and food isolates harbored more often the antibiotic resistance genes markers. Seventeen (28.3%) methicillin-resistant Staphylococcus aureus carrying the mecA gene localized on a SCCmec type IV element were identified. The penicillinase operon (blaZ/I/R) was found in 71.7% (43/60) of isolates. Food isolates belonging to CC97-MSSA carried several antibiotic resistance genes (blaZ, ermB, aphA3, sat, tetM, and tetK). The results of this study showed that all clones were found in their typical host, but interestingly, some nasal carriers had isolates assigned to CC705 thought to be absent in humans. The detection of MRSA strains among food isolates should be considered as a potential public health risk. Therefore, controlling the antibiotics prescription for a rational use in human and animal infections is mandatory.

MEDICAL EVALUATION OF THE POTENTIAL BIOLOGICAL AND CHEMICAL DANGERS IN HIGH-RISK FOODS

Purpose: The current European legislation assigned the responsibility for food safety to the food producers and traders. In this aspect, the aim of the survey was to provide critical analysis of the functioning of Hazard Analysis and Critical Control Point (HACCP) systems in the production of foods, presenting certain risks of specific public health hazards - foodborne toxicoinfections, infections and intoxications, for chemical contamination and additives, etc. The survey covered HACCP-systems and prerequisite programmes of 4 enterprises manufacturing confectionery products, ready-to-serve foods, pasteurized egg products, sterilized canned foods. Material/methods: Monitoring and critical analysis of the In-plant control system and HACCP of four enterprises for the production of: confectionery products, ready-to-serve-dishes in public catering, sterilized canned foods, pasteurized egg semi-ready products Results: The current experience has revealed major defects in hazard analysis, adequacy of critical points, corrective actions and verification procedures. The article contains recommendations and suggestions for improving the work of manufacturers and harmonizing relationships with regulatory authorities in the event of inconsistencies in production. Conclusions: The authors concluded that a comprehensive medical evaluation of the HACCP systems was necessary for the prevention of foodborne diseases.

Distribution of the Emetic Toxin Cereulide in Cow Milk.

Bacillus cereus is frequently associated with food-borne intoxications, and its emetic toxin cereulide causes emesis and nausea after consumption of contaminated foods. The major source for contamination is found within contaminated raw materials containing the highly chemically resistant cereulide, independent of vegetative bacteria cells. Up to date, non-existing removal strategies for cereulide evoke the question of how the toxin is distributed within a food sample, especially cow milk. Milk samples with different milk fat contents were incubated with purified cereulide, separated by centrifugation into a lipid and an aqueous phase, and cereulide was quantified in both fractions by SIDA-LC-MS/MS. By artificially increasing the milk fat content from 0.5% to 50%, the amount of cereulide recovered in the lipid phase and could be augmented from 13.3 to 78.6%. Further, the ratio of cereulide increased in the lipid phase of milk with additional plant-based lipid (sunflower oil) to 47.8%. This demonstrated a clear affinity of cereulide towards the hydrophobic, lipid phase, aligning with cereulide’s naturally strong hydrophobic properties. Therefore, an intensified cereulide analysis of lipid enriched dairy products to prevent severe cereulide intoxications or cross-contamination in processed foods is suggested.

A Review of Microbial Contamination in Processed and Street Foods

As a basic physiology need threat to sufficient food, production is threat to human survival food security was a main issue that has gained global concern. This paper looks at the food borne contamination by assessing the availability of food and accessibility of the available food from a food as a microbiologist’s perspective, there are several microorganisms similarly viruses, bacteria, fungi, protozoans, and parasites for which foods serve as vehicles of transmission. Among these agents, several bacteria are most commonly implicated in foodborne outbreak episodes. Foodborne diseases in human beings are caused either by straight contact with infested food animals/animal products (zoonotic) or humans, such as a food handler, or by direct absorption of polluted foods. There are three important terms with regard to foodborne diseases foodborne infections, foodborne toxicoinfections and foodborne intoxications. Foodborne infection is the condition caused by the incorporation of viable cells of a pathogen. For example, Salmonella Enteritidis and Escherichia coli infections are brought about by the ingestion of food contaminated with living cells of these pathogens. Finally, foodborne toxicoinfection is that in which the ingestion of viable pathogenic cells causes the toxins productions inside the human body, leading to infection episodes. For example, Vibrio cholerae produces cholera toxin inside the body after being ingested by the host. The morphology, Gram’s reaction, biochemical properties, and associated foods with important foodborne bacteria.

Evaluation of Bacterial Load and Antibiotic Resistance Pattern of Staphylococcus aureus from Ready-to-Eat Raw Beef in Bahir Dar City, Ethiopia.

Background Staphylococcus aureus is one of the most important causes of food-borne intoxication and the most frequent antibiotic-resistant pathogen in the world. Regular evaluation of the current safety status of food is a proactive measure to minimize the possible danger of food-borne pathogens. Therefore, this study was conducted to assess the bacterial load and antibiotic resistance profile of S. aureus from ready-to-eat raw beef in Bahir Dar city, Ethiopia. Methodology. This cross-sectional study was conducted from October 2018 to April 2019 by collecting a total of 101 raw beef samples from butcher shops using a simple random sampling method. Isolation and microbial load determination of S. aureus use were performed by conventional culture method and an antibiotic susceptibility test was conducted by using Kirby Bauer disk diffusion method on the Mueller–Hinton agar. The data were analyzed by using STATA software version 12.0. Result Out of 101 raw beef samples, 55 (54.45%) were positive for S. aureus with a mean bacterial count of 3.40 ± 0.63 (log10 cfu/g). About 13% of butcher shops had unacceptable and potentially dangerous (above 104 cfu/g) bacterial load. High S. aureus drug resistance was observed on penicillin (92.73%) followed by cefoxitin (74.5%), tetracycline (63.63%), and clindamycin (50.9%). On the other hand, there was the highest susceptibility for ciprofloxacin (100%) followed by gentamycin (90.91%) and erythromycin (87.27%). Multidrug resistance was also found in 54 (98%) of the isolates. Conclusion In this study highly drug-resistant S. aureus was incriminated as the main meat contaminant in butcheries of Bahir Dar city. Therefore, appropriate antimicrobial use and staphylococcal control methods should be employed to prevent S. aureus intoxications in foods.

Relationship between Salinity and Histamine Accumulation in Padaek, a Salt-Fermented Freshwater Fish Paste from Laos

Padaek is a salt-fermented freshwater fish product popularly used in Laos as a shelf-stable all-purpose seasoning. For padaek production, the fish is fermented with salt and rice bran at ambient temperature. Although it is considered edible after 2 to 3 months of fermentation, 6 to 12 months is required to enhance its palatability. Its long shelf life and abundance of free amino acids, such as glutamate and lysine, are distinctive features of the product. Although commercial products are currently available, the tradition of making and consuming padaek at home continues, particularly in rural areas, to make use of indigenous freshwater fish, which provides a continuous supply of food and nutrition. Histamine can cause foodborne intoxication. Occasionally, its excessive accumulation occurs in amino acid-containing food, such as fermented fish products, because of the growth of microorganisms with histidine decarboxylase activity. We found a negative correlation between salinity and histamine content in homemade padaek products collected from rural households. Experimental padaek fermentation with initial salinity conditions of 10 and 6.5% exhibited significant histamine accumulation after 2 weeks of incubation at 30°C and exceeded 1,000 ppm within 6 months, but no histamine was detected in fermentation with an initial salinity of 18% over the same period. This indicated that salinity was a critical factor for controlling the risk of histamine accumulation during padaek fermentation. We, therefore, created and used a simplified calculation chart to help local households adjust the initial salinity to a sufficient level to reduce histamine accumulation during padaek fermentation. This producer-friendly approach for reducing the risk of histamine accumulation in this popular fermented food in Laos should be widely implemented to enhance food safety management in the country.

Prevalence of the Enterotoxigenic Staphylococcus Aureus Strains Isolated from Raw Milk and Cheese Produced in North Macedonia

Abstract Staphylococcus aureus is an important foodborne pathogen due to toxin-related virulence, invasiveness and antibiotic resistance. The ability of S. aureus strains to produce one or more staphylococcal enterotoxins (SEs) in food has been associated with the occurrence of staphylococcal food poisoning (SFP), which is the most common foodborne intoxication worldwide. The study aimed to determine the count of S. aureus strains in samples of raw cow’s milk and various cheeses produced in R. North Macedonia and to detect their ability to produce enterotoxins by passive agglutination SET RPLA (OXOID, UK) and by enzyme-linked fluorescence assay (ELFA) VIDAS SET 2 (Biomerieux, France). A total of 130 S. aureus strains were analyzed. The ability to produce SEs was determined in 17 (13.1%) strains using the SET RPLA detection kit and in 20 (15.4%) strains using the VIDAS SET 2. The study detected enterotoxigenic strains in cheese samples, despite the low count of S. aureus which was below the detection limit according to the Book of rules for microbiological criteria (Off. G. of R.M no 100/2013). Based on these and similar findings, S. aureus must be considered as a possible cause of intoxication, despite the undetected and underreported cases of SFP in the scientific literature.