Category Archives: Staphylococcus aureus

Research – Prevalence, antimicrobial susceptibility and virulence genes of Staphylococcus aureus isolated from pork meat in retail outlets in India

Posted on February 16, 2019 by | Leave a comment

Wiley Online

Abstract

Isolation of Staphylococcus aureus was carried out in a total of 120 retail pork samples and the overall prevalence of S. aureus in retail pork meat was 76.67%. All the isolates were resistant to both Ampicillin and Tetracycline (100%) followed by Cefoxitin, Oxacillin, Erythromycin, Amoxicillin, and Novobiocin. The multiple antibiotic resistance index of majority of the isolates were 0.3 and above. Methicillin resistance based on polymerase chain reaction revealed that 76.09% carried either mecA or mecC. The prevalence of enterotoxigenic S. aureus in pork was 82.61% and of the various toxin genes sei was the major gene followed by seg, seb, sej, sed, seh, sec, and sea in decreasing order. The prevalence of multidrug resistant and virulent S. aureus carrying enterotoxin genes in retail pork meat is a clear indication of the potential of these isolates in causing foodborne intoxication under favorable conditions to the consumers.

Practical application

Staphylococcus aureus (S. aureus) is a well‐known opportunistic pathogen widely present in a broad host range, including human beings and food producing animals, such as pigs, cows, goats and chickens. It has the potential to contaminate animal products and they gain entry in to the food chain, during processing, preparation and storage. The wide use of antibiotics has led to the emergence of multi drug resistant strains, particularly Methicillin‐resistant S. aureus (MRSA). The present study highlights the prevalence, antimicrobial resistance with special reference to MRSA and enterotoxin gene profile of S. aureus isolated from retail pork meat. The results will provide the insights of the existing situation of antimicrobial resistance in pork meat in India.

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Posted in Food Hygiene, Food Illness, Food Inspections, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Poisoning, Food Safety, Food Testing, Food Toxin, Staphylococcus aureus, Toxin, Uncategorized

Research – Survival of food‐borne bacterial pathogens in traditional Mediterranean anchovy products

Posted on February 14, 2019 by | Leave a comment

Wiley Online Library

Abstract

The aim of this study was to investigate the survival of Salmonella Enteritidis, Staphylococcus aureus and Listeria monocytogenes in salted and marinated anchovy (Engraulis encrasicholus). Total viable counts (TVCs), lactic acid bacteria, Enterobacteriaceae, and yeasts/molds were also enumerated. Initially, TVC was as high as 5.5 log10 cfu/g, but the population dropped down to 3.2 and 2.2 log10 CFU/g for salted and marinated anchovy, respectively. S. aureus was the most salt‐tolerant and L. monocytogenes was the most acid‐tolerant microorganism. A biphasic inactivation of S. Enteriditis and L. monocytogenes was apparent during the 8‐hr marination process, implying adaptation and resistance to low pH. Results suggest that salting or marinating of anchovy creates an environment in which pathogenic bacteria are inactivated. However, inherent resistance or possible adaptation to stresses can result to prolonged inactivation times; hence it is important to avoid contamination with high numbers of food‐borne pathogens.

Practical applications

Many food‐borne bacterial pathogens can survive at low pH and aw, especially in cases in which they might adapt to the imposed stresses and become resistant. Knowing the time required to reduce food‐borne pathogens is of great interest for ensuring safety of traditional seafood.

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Posted in Enterobacteriaceae, Food Hygiene, Food Inspections, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Pathogen, Food Safety, Food Testing, lactic acid bacteria, Listeria, Listeria monocytogenes, Moulds, Salmonella, Staphylococcus aureus, Total Viable Count, Uncategorized, Yeasts

Research – Lactic acid fermentation of legume seed sprouts as a method of increasing the content of isoflavones and reducing microbial contamination

Posted on February 14, 2019 by | Leave a comment

Science Direct

CDC Klebsiella

Image CDC

Legume seeds and sprouts are a rich source of phytoestrogens in the form of isoflavonoids. For the first time, lactic acid fermentation of four types of legume sprouts was used to increase the content of isoflavonoids and microbiological safety. After germination, the highest content of isoflavonoids was observed in the clover and chickpea sprouts, which amounted to 1.1 g/100 g dw., whereas the lactic acid fermentation allowed the increase to as much as 5.5 g/100 g dw. The most beneficial properties were shown by fermented chickpea sprouts germinated in blue light. During fermentation the number of lactic acid bacteria increased by 2 Log10CFU/mL (LU), whereas mold decreased by 1 LU, E.coli and Klebsiellasp. by 2 LU, Salmonella sp. and Shigella sp did not occur after fermentation, similar to Staphylococcus epidermidis, while S. aureus and S. saprophyticus decreased by 3 LU and in some trials were not detected.

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Posted in Food Inspections, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Poisoning, Food Safety, Food Technology, Food Testing, Isoflavonoids, Klebsiella, lactic acid bacteria, Salmonella, Staphylococcus aureus, Uncategorized

Research -Identification and Spoilage Potential of the Remaining Dominant Microbiota on Food Contact Surfaces after Cleaning and Disinfection in Different Food Industries

Posted on February 3, 2019 by | Leave a comment

Journal of Food Protection

After cleaning and disinfection (C&D), surface contamination can still be present in the production environment of food companies. Microbiological contamination on cleaned surfaces can be transferred to the manufactured food and consequently lead to foodborne illness and early food spoilage. However, knowledge about the microbiological composition of residual contamination after C&D and the effect of this contamination on food spoilage is lacking in various food sectors. In this study, we identified the remaining dominant microbiota on food contact surfaces after C&D in seven food companies and assessed the spoilage potential of the microbiota under laboratory conditions. The dominant microbiota on surfaces contaminated at ≥102 CFU/100 cm2 after C&D was identified based on 16S rRNA sequences. The ability of these microorganisms to hydrolyze proteins, lipids, and phospholipids, ferment glucose and lactose, produce hydrogen sulfide, and degrade starch and gelatin also was evaluated. Genera that were most abundant among the dominant microbiota on food contact surfaces after C&D were Pseudomonas, Microbacterium, Stenotrophomonas, Staphylococcus, and Streptococcus. Pseudomonas spp. were identified in five of the participating food companies, and 86.8% of the isolates evaluated had spoilage potential in the laboratory tests. Microbacterium and Stenotrophomonas spp. were identified in five and six of the food companies, respectively, and all tested isolates had spoilage potential. This information will be useful for food companies in their quest to characterize surface contamination after C&D, to identify causes of microbiological food contamination and spoilage, and to determine the need for more thorough C&D.

 

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Posted in Faecal Streptpcocci, food contamination, Food Hygiene, Food Inspections, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Safety, Food Technology, Food Testing, Pseudomonas, Staphylococcus aureus, Uncategorized

Research – The effect of silver nanocomposite packaging based on melt mixing and sol–gel methods on shelf life extension of fresh chicken stored at 4 °C

Posted on January 27, 2019 by | Leave a comment

Online Library

Abstract

In the present study, seven types of films were produced using different proportions of polyethylene containing silver, clay, and titanium dioxide nanoparticles. Following the determination of the minimum inhibitory concentration of the films in the eradication of Staphylococcus aureus and Escherichia coli, the film containing 5% silver nanoparticles and 5% titanium dioxide nanoparticles was found to have the highest antimicrobial property and was determined to be an ideal cover for food products. The antibacterial effect of the films on the shelf life extension and quality of the chicken stored at 4 °C in the Days 1, 3, and 5 of the experiment was checked. The structure and morphology of the nanoparticles and the selected films were evaluated using a field emission scanning electron microscope, scanning electron microscope, transmission electron microscope, Fourier‐transform infrared spectroscopy, and dynamic light scattering. The analysis of the results indicated that the most appropriate inhibition growth was observed with S. aureus and E. coli in nutrient agar and the largest diameter of the radial inhibition zone occurred with S. aureus. Moreover, the analysis of variance showed that the effect of different concentrations of silver and titanium dioxide nanoparticles was significant (p < .05). The results of this study showed that the produced nanocomposite was used to preserve chicken meat for 5 days at 4 °C inhibited the growth of both types of bacteria.

Practical applications

Nowadays production of active packaging is increasing worldwide as they were proved to have numerous effects on inhibiting of microbial growth and even bactericidal effects. Therefore, a wide variety of food producers in different sections namely agriculture, dairy, and meat industries have applied nanopackaging using different nanoparticles. Thus, more research on different physicochemical and antimicrobial effects are needed.

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Posted in Active Packagin, E.coli, Staphylococcus aureus, Uncategorized

Research – Anti-adhesion of probiotic Enterococcus faecium WEFA23 against five pathogens and the beneficial effect of its S-layer proteins against Listeria monocytogenes

Posted on January 27, 2019 by | Leave a comment

Canadian Journal of Microbiology

Enterococcus faecium WEFA23 is a potential probiotic strain isolated from Chinese infant feces. In this study, the antagonistic activity of E. faecium WEFA23 on adhesion to pathogens was investigated. Enterococcus faecium WEFA23 was able to compete, exclude, and displace the adhesion of Escherichia coli O157:H7, Salmonella Typhimurium ATCC 13311, Listeria monocytogenes CMCC54007, Staphylococcus aureus CMCC26003, and Shigella sonnei ATCC 25931 to Caco-2 cells. Among them, L. monocytogenes achieved the strongest inhibition rate in both competition and displacement assays. Those anti-adhesion capacities were related to the bacterial physicochemical properties (hydrophobicity, auto-aggregation, and co-aggregation) of the bacterial surface. For L. monocytogenes, the anti-adhesion capacity was affected by the heat treatment, cell density, and growth phase of E. faecium WEFA23; 108 colony-forming units of viable cells per millilitre at the stationary phase exhibited the strongest anti-adhesion activity. In addition, removal of S-layer proteins of E. faecium WEFA23 by treatment with 5 mol/L LiCl significantly decreased its adhesion capacity, and those S-layer proteins were able to compete, displace, and exclude L. monocytogenes at different levels. Both cells and S-layer proteins of E. faecium WEFA23 significantly reduced the apoptosis of Caco-2 cells induced by L. monocytogenes, which was mediated by caspase-3 activation. This study might be helpful in understanding the anti-adhesion mechanism of probiotics against pathogens.

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Posted in Enterococcus, Listeria, Listeria monocytogenes, Salmonella, Shigella, Staphylococcus aureus, Uncategorized

Research – Wiping out MRSA: effect of introducing a universal disinfection wipe in a large UK teaching hospital

Posted on January 2, 2019 by | Leave a comment

ARIC Journal

mrsa

Background

Contamination of the inanimate environment around patients constitutes an important reservoir of MRSA. Here we describe the effect of introducing a universal disinfection wipe in all wards on the rates of MRSA acquisitions and bacteraemias across a large UK teaching hospital.

Methods

A segmented Poisson regression model was used to detect any significant changes in the monthly numbers per 100,000 bed days of MRSA acquisitions and bacteraemias from April 2013 – December 2017 across QEHB.

Results

From April 2013 to April 2016, cleaning of ward areas and multi-use patient equipment by nursing staff consisted of a two-wipe system. Firstly, a detergent wipe was used, which was followed by a disinfection step using an alcohol wipe. In May 2016, QEHB discontinued the use of a two-wipe system for cleaning and changed to a one wipe system utilising a combined cleaning and disinfection wipe containing a quaternary ammonium compound. The segmented Poisson regression model demonstrated that the rate of MRSA acquisition/100,000 patient bed days was affected by the introduction of the new wiping regime (20.7 to 9.4 per 100,000 patient bed days; p <0.005).

Discussion

Using a Poisson model we demonstrated that the average hospital acquisition rate of MRSA/100,000 patient bed days reduced by 6.3% per month after the introduction of the new universal wipe.

Conclusion

We suggest that using a simple one wipe system for nurse cleaning is an effective strategy to reduce the spread and incidence of healthcare associated MRSA.

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Posted in Antimicrobials, Food Micro Blog, Food Microbiology Blog, Food Technology, microbial contamination, Microbiology, MRSA, Staphylococcus aureus, Technology, Uncategorized

Research – Control of pathogens in cheeses made from unpasteurised milk

Posted on December 19, 2018 by | Leave a comment

HPS Scotland

A new report, prepared for Food Standards Scotland (FSS), outlines the scientific evidence on food safety controls, which can be used to reduce the risks of food poisoning bacteria in the production of raw milk cheeses.

The report, by Dr Catherine Donnelly, was prepared to supply evidence for Scottish artisan cheesemakers and enforcement officials in managing the microbiological safety of artisan cheeses, particularly those produced from unpasteurised milk. The main pathogens of concern posing a risk to the safety of cheeses made from unpasteurised milk are Listeria monocytogenes, Shiga toxin-producing Escherichia coli, Salmonella and Staphylococcus aureus.

The report, which is in three parts:

  • examines categorisation of commonly produced cheese types in Scotland and provides an overview of potential critical control points (CCPs) at each stage of the cheesemaking process, in order to control bacterial pathogens of primary concern;
  • analyses currently available predictive models, challenge testing methods and results of challenge testing, providing evidence of the safety, or lack thereof, attained during cheesemaking;
  • provides an analysis of microbiological and physicochemical results obtained from cheesemakers, as well as from the scientific literature and recommendations on testing targets and frequencies to assure process control and production of microbiologically safe products.

‘Review of controls for pathogen risks in Scottish artisan cheeses made from unpasteurised milk’ can be accessed at: https://www.foodstandards.gov.scot/downloads/FSS_2017_015_-_Control_of_path….

[Source: FSA, 12 December 2018. https://www.foodstandards.gov.scot/publications-and-research/publications/c…]

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Posted in E.coli, Raw Milk, Salmonella, Staphylococcus aureus, Uncategorized

Hong Kong – Test results on microbiological quality of poon choi all satisfactory

Posted on December 6, 2018 by | Leave a comment

CFS

 

The Centre for Food Safety (CFS) of the Food and Environmental Hygiene Department today (November 26) announced the test results of a recently completed seasonal food surveillance project on the microbiological quality of poon choi. Thirty samples were collected and all passed the tests.

A CFS spokesman said, “As poon choi is popular for gatherings during winter and there were previous cases of bacterial food poisoning associated with poon choi, the CFS has continued to conduct a seasonal food surveillance project this year to assess the microbiological quality of poon choi. A total of 30 poon choi samples were collected from different retailers (including online retailers) for testing of common food poisoning organisms including Bacillus cereus, Clostridium perfringens, Salmonella, coagulase-positive staphylococci organisms and Vibrio parahaemolyticus.”

Despite the satisfactory results of all samples tested, the spokesman reminded people to be careful when purchasing and enjoying this seasonal delicacy. He advised consumers to order poon choi from licensed and reliable shops, avoid prolonged storage of poon choi at room temperature to reduce the risk of bacteria growth, reheat poon choi thoroughly before consumption, consume cooked or reheated poon choi as soon as possible or keep the food at temperatures above 60 degrees Celsius, and stop consuming the food if it tastes or smells abnormal.

“The public should also maintain a balanced diet and avoid eating too much food with high levels of energy, sugar, salt or fat,” the spokesman said.

He also appealed to the food trade not to entertain orders beyond handling capacity. Traders are reminded to check the quality of food and ingredients when they are delivered to them. In addition, to reduce the risk of food poisoning, they should avoid preparing food too far in advance and take note of the temperature in storing, transporting and preparing food.

“All food and food ingredients should be stored at safe temperatures while perishable items should be stored at 4 degrees C or below. The cooling time of cooked food should be reduced as far as possible, for example, by dividing food into smaller portions or placing it in shallow containers. When transporting hot poon choi, it should be kept at above 60 degrees C, and for chilled poon choi, it should be kept at 4 degrees C or below,” the spokesman said.

“Traders should also provide clear advice on the proper methods of storing and reheating of poon choi to consumers so as to further reduce the risk of food poisoning due to improper handling,” he added.

The CFS will continue its surveillance of poon choi available in the market to ensure food safety and protect the health of the public.

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Posted in Bacillus, Bacillus cereus, Clostridium perfringens, food contamination, Food Hygiene, Food Inspections, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Pathogen, Food Safety, Food Safety Alert, Food Testing, Salmonella, Staphylococcus aureus, Uncategorized, Vibrio, Vibrio parahaemolyticus

Research – Behavior of foodborne pathogens, Listeria monocytogenes and Staphylococcus aureus, in mixed-species biofilm exposed to biocides

Posted on December 6, 2018 by | Leave a comment

Orbit

In nature and man-made environments, microorganisms reside in mixed-species biofilm where behavior is modified compared to the single-species biofilms. Pathogenic microorganisms may be protected against adverse treatments in mixed-species biofilms leading to health risk for humans. Here, we developed two mixed-five-species biofilms that included the foodborne pathogens Listeria monocytogenes or Staphylococcus aureus, respectively. The five species, including the pathogen, were isolated from a single food-processing environmental sample thus mimicking the environmental community. In mature mixed five-species biofilms on stainless steel, the two pathogens remained at a constant level of ∼105 CFU/cm2 The mixed-five-species biofilms as well as the pathogens in mono-species biofilms were exposed to biocides to determine any pathogen-protective effect of the mixed biofilm. Both pathogens and their associate microbial communities were reduced by peracetic acid treatments. S. aureus decreased 4.6 log cycles in mono-species biofilm, but the pathogen was protected in the five-species biofilm and decreased only 1.1 log cycles. Sessile cells of L. monocytogenes were affected equally as a mono-biofilm or as a member in the mixed-species biofilm; decreasing by three log cycles when exposed to 0.0375 % peracetic acid. When the pathogen was exchanged in each associate microbial community, S. aureus was eradicated while there was no significant effect of the biocide on L. monocytogenes or the mixed community. This indicates that particular members or associations in the community offered the protective effect. Further studies are needed to clarify the mechanisms of biocide protection, and the species playing the protective role in microbial communities of biofilms. Importance: This study demonstrates that foodborne pathogens can be established in mixed species biofilms and that this can protect them from biocide action. The protection is not due to specific characteristics of the pathogen, here S. aureus and L. monocytogenes, but likely caused by specific members or associations in the mixed species biofilm. Biocide treatment and resistance is a challenge for many industries and biocide efficacy should be tested on microorganisms growing in biofilms, preferably mixed systems, mimicking the application environment.

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Posted in Biofilm, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Listeria, Listeria monocytogenes, microbial contamination, Microbiology, Staphylococcus aureus, Uncategorized, water microbiology