Category Archives: Staphylococcus aureus

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

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 segsebsej, 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.

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

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.

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

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.

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

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.

 

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

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.

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

Canadian Journal of Microbiology

Enterococcus faecium WEFA23 is a potential probiotic strain isolated from Chinese infant feces. In this study, the antagonistic activity of Efaecium 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, Lmonocytogenes 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.

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

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.