Category Archives: Staphylococcus aureus

Research – Anti‐adhesive effects of sialic acid and Lactobacillus plantarum on Staphylococcus aureus in vitro

Posted on November 24, 2020 by | Leave a comment

Journal of Food Safety

Staphylococcus aureus (S. aureus) is a common food‐borne pathogen that causes severe diseases after adhesion to epithelial cells. Lactobacillus inhibits pathogenic bacterial adhesion and infection. In addition, sialic acid (SA) is widely known for its beneficial biological functions. A new way of reducing the occurrence of diseases and curbing the overuse of antibiotics is ingesting prebiotics and probiotics that regulate the intestinal flora. In this study, we first evaluated the anti‐adhesive effects of several strains of Lactobacillus on S. aureus. The study revealed that the S. aureus adhesion was inhibited by all the strains of Lactobacillus. Besides, the rate of inhibition by L. plantarum Z‐4 was significantly higher than other Lactobacillus species. We then investigated the effects of different SA concentrations (40, 100, 150, 200, and 260 μg/ml) on the growth and adhesion characteristics of L. plantarum and S. aureus. The results showed that SA influences bacterial adhesion by regulating the bacteria’s growth characteristics. Finally, the effects of SA combined with Lactobacillus on the adhesion of S. aureus were assessed by competition, exclusion and displacement methods. SA with a concentration of 260 μg/mL combined with L. plantarum had the highest inhibition effect on the competition assays. In addition, the expression of S. aureus adhesion‐related genes was reduced. This provides a new perspective on the application of SA and/or L. plantarum and its potential to resist adhesion of S. aureus.

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Posted in food contamination, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, Food Pathogen, Food Poisoning, food recall, Food Safety, Food Technology, Food Testing, Lactobacillus plantarum, Research, Staphylococcus aureus, Technology

Research – Microbiological control of pasteurized and unpasteurized dairy products, 2018 – Norway

Posted on November 19, 2020 by | Leave a comment

Mattilsynet

The microbiological quality was generally good for the 189 dairy products on the Norwegian market that the Norwegian Food Safety Authority examined in 2018. Nevertheless, we see that there are microbiological challenges in connection with unpasteurized dairy products.

What did we investigate? 189 samples of unpasteurized and pasteurized cheeses and other dairy products produced in Norway and in the EU.
Period: 2018
What were we looking for? The four categories have been analyzed for various disease-causing bacteria (pathogens). These choices are made in order to get the most information for each category.

The different categories are:

PN = pasteurized milk product produced in Norway.

P EU = pasteurized milk product produced outside Norway.

UN = unpasteurized milk product produced in Norway.

U EU = unpasteurized milk product produced outside Norway.
The various disease-causing infectious agents we analyzed for:

Listeria monocytogenes (pathogen): PN, P EU, UN, U EU, number 189 pcs.

Shigatoxin-producing Escherichia coli (STEC) (pathogen): UN, U EU, number 96 pcs.

E. coli (hygiene parameter): PN, UN, U EU, 169 st.

S. aureus (hygiene parameter): UN, number 71 st.

Toxins (enterotoxin) from S. aureus (pathogen): UN, U EU, number 96 pcs.

Salmonella (pathogen): U EU, number 25 st.
What did we find? Listeria monocytogenes : No detection in 189 samples of dairy product.

Shigatoxin-producing Escherichia coli (STEC):
One finding in French red cow cheese of cow’s milk ( E. coli O-, stx2 and eae ). A total of 25 unpasteurized milk products produced outside Norway were examined. No findings in 71 unpasteurized milk products from Norway.

Escherichia coli (hygiene parameter):
In 73 pasteurized milk products from Norway, there was a detection and this was above the lower limit value (100 kde / g) but below the upper limit value (1,000 kde / g). No E. coli was detected above the detection limit of 10 colony forming units / g sample (kde / g) in the other samples.

In 61 of the 71 unpasteurized milk products produced in Norway, E. coli was not detected above the detection limit of 10 colony-forming units / g sample (kde / g). 3 st. (4.2%) was above 100 kde / g.

In unpasteurized dairy products from the EU (25), 5 (20%) of the products had more than 100 kde / g E. coli. There is no microbiological criterion for E. coli in the regulations for unpasteurized cheeses.

Staphylococcus aureus:
Of 71 samples, none exceeded the regulatory limit of 10,000 kde / g.

Of the 96 unpasteurized dairy products examined, the enterotoxins AE Toxins (enterotoxins), which some S. aureus can produce , were not detected .

Salmonella was not detected in the 25 samples of unpasteurized milk products produced outside Norway.

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Posted in Bacteria, bacterial contamination, E.coli, Food Toxin, Listeria, Listeria monocytogenes, Salmonella, Staphylococcus aureus, STEC, STEC E.coli, Toxin

RASFF Alerts – Microbial Contamination – microbial contamination (yeasts, molds, Staphylococcus aureus) of pyramide cake products and rum balls

Posted on November 6, 2020 by | Leave a comment

European Food Alerts

RASFF

microbial contamination (yeasts, molds, Staphylococcus aureus) of pyramide cake products and rum balls from Germany in Germany

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Posted in food contamination, Food Hygiene, Food Inspections, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Testing, food recall, Food Safety, Food Testing, microbial contamination, Microbiology, Moulds, RASFF, Staphylococcus aureus, Yeasts

Research – Microbiological Quality of Cooked Chicken: Results of Monitoring in England (2013 to 2017)

Posted on November 2, 2020 by | Leave a comment

Journal of Food Protection

Results from monitoring of the microbiological quality of 2,721 samples of ready-to-eat cooked chicken collected between 2013 to 2017 in England were reviewed: 70% of samples were from retail, catering, or manufacture and 30% were imported and collected at English ports. Samples were tested for a range of bacterial pathogens and indicator organisms. Six samples (<1%) had unsatisfactory levels of pathogens that were potentially injurious to health. Neither Salmonella nor Campylobacter were recovered from any samples. Two samples from catering settings contained either an unsatisfactory level of Bacillus cereus (5 × 106 CFU/g) or an unsatisfactory level of coagulase-positive staphylococci (1.6 × 104 CFU/g). Listeria monocytogenes was recovered from 36 samples (1 at manufacture, 26 at catering, and 9 at retail) and in 4 samples, unsatisfactory levels (≥102 CFU/g) were detected (3 samples collected at catering and 1 sample at retail). For L. monocytogenes, there were no significant differences between the rates of contamination for the samples collected from ports, manufacture, retail supermarkets, and other retailers (P = 0.288). There were no differences between the rates of contamination for other potential pathogens detected between samples from different settings. The prevalence of hygiene indicators (Escherichia coli, Enterobacteriaceae, and aerobic colony counts) at import was significantly lower than in samples collected from manufacturers, retail, or catering (P < 0.01). Samples collected from catering gave poorer results than those from all other settings. Regardless of the stage in the food chain, samples from Thailand and from other non–European Union countries were of significantly better microbiological quality with respect to indicator organisms than those from the United Kingdom or from other European Union countries (P = <0.001).

HIGHLIGHTS
  • Routine microbiological monitoring of 2,721 samples was reviewed.
  • Six samples (<1%) were unsatisfactory due to the levels of bacterial pathogens.
  • Hygiene indicator bacteria were significantly higher in samples from catering.
  • Port samples had significantly lower levels of hygiene indicators.

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Posted in Bacillus cereus, Campylobacter, E.coli, Enterobacteriaceae, Food Microbiology Research, Listeria, Listeria monocytogenes, Research, Salmonella, Salmonella in Chicken, Staphylococcus aureus

Research – Evaluation of Listeria monocytogenes and Staphylococcus aureus survival and growth during cooling of hams cured with natural-source nitrite

Posted on November 1, 2020 by | Leave a comment

Journal of Food Protection

Growing consumer desires for clean label, “natural” products drives more meat processors to cure meat products with natural sources of nitrate or nitrite such as celery juice powder (CJP). One particular challenge for these producers is to identify safe cooling rates in CJP-cured products where extended cooling could allow growth of pathogens. USDA FSIS recently added guidelines for stabilization of meat products cured using naturally occurring nitrites, based on control of Clostridium spp . Currently a gap exists in knowledge associated with safe cooling rates of naturally cured ham that prevent the growth of Listeria monocytogenes and Staphylococcus aureus that are potential post-lethality contaminants. The study aims to investigate the temperature profiles of naturally cured hams of typical sizes during refrigerator cooling and determine the survival behavior of S. aureus and L. monocytogenes on ham during these cooling periods. Whole (14 lbs / 6300 g), half (6 lbs / 2700 g) and quarter hams (3 lbs / 1400 g) were slowly cooked in Alkar Ò 1000 smokehouse until internal temperatures reached a minimum of 140 ° F / 60°C and were immediately transferred into walk-in cooler (38 ° F / 3.3°C). Cooling times for all sizes were within the requirements for cured products but not for uncured products. Worst-case scenarios of post-processing surface contamination were simulated by inoculating small, naturally cured ham samples with S. aureus or L. monocytogenes , which were cooled in controlled processes (130-45 ° F / 54.4-7.2 ° C in 720-900 min). B y the end of cooling, each inoculum had a small decrease of 0.5-0.6 log CFU/g. This study helps small processors identify if recommended concentrations of natural cure agents that prevent growth of Clostridium pathogens may also prevent growth of other pathogens during cooling, which aids small meat processors in production and quality control.

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Posted in Bacteria, bacterial contamination, Clostridium, Clostridium Sulphite Reducer, Food Microbiology Research, Listeria, Listeria monocytogenes, Research, Staphylococcus aureus

Research – Antimicrobial and preservative effects of the combinations of nisin, tea polyphenols, rosemary extract and chitosan on pasteurized chicken sausage

Posted on October 7, 2020 by | Leave a comment

Journal of Food Protection

The study evaluated the antimicrobial and antioxidant effects of the combinations of nisin (NS), tea polyphenols (TP), rosemary extract (RE) and chitosan (CS) on low-temperature chicken sausage. An orthogonal test revealed that the most effective antimicrobial compositions were equal-quantity mixtures of 0.05% NS + 0.05% TP + 0.03% RE + 0.55% CS . The mixture also produced strong antimicrobial and antioxidant effects in low-temperature chicken sausage related to extend the shelf life to more than 30 days at 4°C. The study also investigated the inhibitory zone of NS, TP, RE and CS against Pseudomonas aeruginosa , lactic acid bacteria (LAB) and Staphylococcus aureus which were the dominant spoilage bacteria in low-temperature chicken sausage. NS had the greatest inhibitory effect on LAB and Staphylococcus aureus , exhibiting clear zone diameters of 19.7 mm and 17.8 mm respectively. TP had the largest inhibitory effect on Pseudomonas aeruginosa , exhibiting a clear zone diameter of 18.2 mm. These results indicated that the combination of NS, TP, RE and CS could be used as natural preservative s to efficiently inhibit the growth of spoilage microorganisms in low-temperature chicken sausage so as to improve its safety and shelf life.

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Posted in Bacteria, bacterial contamination, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Testing, Food Pathogen, Food Safety, Food Spoilage, Food Testing, lactic acid bacteria, pathogenic, Pseudomonas, Pseudomonas aeruginosa, Shelf Life, Staphylococcus aureus

Research – Surveillance of foodborne disease outbreaks in China, 2003–2017

Posted on September 20, 2020 by | Leave a comment

Science Direct

Foodborne disease remains a major public health problem worldwide. To understand the epidemiology and changes of foodborne disease in China, data reported to the National Foodborne Disease Outbreak Surveillance System during 2003–2017 were collected. A total of 19,517 outbreaks, which resulted in 235,754 illnesses, 107,470 hospitalizations, and 1,457 deaths, were reported in this period. Of the 13,307 outbreaks with known etiology, 31.8% of outbreaks were caused by poisonous mushrooms, followed by Vibrio parahaemolyticus (11.3%), saponin (8.0%), Salmonella (6.8%), nitrite (6.4%), pesticide (4.8%), Staphylococcus aureus (4.2%) and Bacillus cereus (3.0%). Among 18,955 outbreaks with reported setting, 46.6% were associated with food prepared in a household, followed by 22.5% with food prepared in a restaurant, and 18.4% prepared in a canteen. Of the 13,305 outbreaks associated with a single food category, fungi (mainly poisonous mushroom) were the most commonly implicated food category, followed by meats, vegetables, aquatic animals, condiments, poisonous plants (such as saponin, tung oil or seed, aconite) and grains (such as rice, noodle, rice noodle). Analysis of foodborne disease outbreaks can provide insight into the most important causative agents and sources of foodborne disease, and assist public health agencies determine the high-risk etiology and food pairs, specific points of contamination and settings to reduce foodborne disease illnesses.

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Posted in Bacillus, Bacillus cereus, Bacteria, bacterial contamination, food contamination, Food Hygiene, Food Illness, Food Inspections, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, Food Pathogen, Food Poisoning, food recall, Food Safety, Food Safety Alert, Food Testing, Food Toxin, Foodborne Illness, foodborne outbreak, foodbourne outbreak, microbial contamination, Microbiology, Salmonella, Staphylococcus aureus, Vibrio parahaemolyticus

Research – Microbiological quality of raw drinking milk and unpasteurised dairy products: results from England 2013–2019

Posted on August 26, 2020 by | Leave a comment

cambridge.org

The aim of this study was to review microbiology results from testing >2500 raw drinking milk and dairy products made with unpasteurised milk examined in England between 2013 and 2019. Samples were collected as part of incidents of contamination, investigation of infections or as part of routine monitoring and were tested using standard methods for a range of both pathogens and hygiene indicators. Results from testing samples of raw cow’s milk or cheese made from unpasteurised milk for routine monitoring purposes were overall of better microbiological quality than those collected during incident or investigations of infections. Results from routine monitoring were satisfactory for 62% of milks, 82% of cream, 100% of ice-cream, 51% of butter, 63% of kefir and 79% of cheeses, with 5% of all samples being considered potentially hazardous. Analysis of data from cheese demonstrated a significant association between increasing levels of indicator Escherichia coli with elevated levels of coagulase positive staphylococci and decreased probability of isolation of Shiga toxin-producing E. coli. These data highlight the public health risk associated with these products and provide further justification for controls applied to raw drinking milk and dairy products made with unpasteurised milk.

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Posted in E.coli, Food Microbiology Research, Raw Milk, raw milk cheese, Research, Staphylococcus aureus, STEC, STEC E.coli, Uncategorized

Research – SSEL, a selective enrichment broth for simultaneous growth of Salmonella enterica, Staphylococcus aureus, Escherichia coli O157: H7, and Listeria monocytogenes

Posted on August 14, 2020 by | Leave a comment

Wiley Online

Salmonella enterica, Staphylococcus aureus, Escherichia coli O157: H7, and Listeria monocytogenes may contaminate similar types of food and cause foodborne disease. The objective of this study was to develop a selective enrichment broth for simultaneous enrichment of Salmonella enterica, Staphylococcus aureus, Escherichia coli O157: H7, and Listeria monocytogenes (SSEL) using nalidixic acid, acriflavine, lithium chloride, and sodium cholate as selective agents. Developed SSEL broth not only enriched the target pathogens to 5 log10 CFU/ml after 18 hr incubation at 37°C with 10–100 CFU/mL of inoculation concentration, but also could successfully support the simultaneous enrichment of target pathogens with similar growth rates and inhibit the growth of most nontarget bacteria effectively. The enrichment effect of SSEL was confirmed by artificial contamination test coupled with multiplex PCR. In summary, SSEL has been shown to be a promising multiplex selective enrichment broth for the detection of the four pathogens on a single‐assay platform.

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Posted in E.coli O157, E.coli O157:H7, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, Listeria, Listeria monocytogenes, microbial contamination, Microbiology, Research, Salmonella, Staphylococcus aureus, Uncategorized

Research – Survival of Staphylococcus aureus and Salmonella enteritidis on salted sardines (Sardina pilchardus) during ripening

Posted on August 9, 2020 by | Leave a comment

PubMed

The ripening period for salted sardines ranges from 4 to 6 months, depending on the season. Sometimes producing industries need to distribute the product earlier owing to market needs, and when this happens the product’s safety needs to be assured. The purpose of this work was to study the survival of Staphylococcus aureus and Salmonella Enteritidis on salted sardines during a ripening period of 115 days. Salted sardines were inoculated with pure cultures of S. aureus and Salmonella Enteritidis (10(5) CFU/g of fish on day 0). After 5 days of ripening, the water activity value for the sardines decreased from 0.93 to 0.69. The survival of both pathogens and that of total viable cells were evaluated during the ripening process. Total viable counts decreased by 2 log units over the 115-day ripening period. Salmonella Enteritidis and S. aureus survived for 60 and 90 days, respectively. Therefore, the use of a 90-day ripening period could be effective in assuring the safety of the final product.

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Posted in Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, microbial contamination, Microbiology, Research, Salmonella, Staphylococcus aureus, Uncategorized