Sterilization Staphylococcus aureus

The mold isolated by Alexander Fleming in early 1940s was Penicillium notatum, who noted that this species killed his culture of Staphylococcus aureus. The production of penicillin is now done by a better penicillin-producing mould species, Penicillium chryso-genum. Development of submerged culture techniques enhanced the cultivation of the mould in large-scale operation by using a sterile air supply. 

Materials Required Standard chlortertracyline sterilized media (as described above) 1 L authentic and pure strain of microorganism Staphylococcus aureus (NCTC 6571) formaldehyde solution (34-37% w/v) 10 ml matched identical test tubes 20 ... 

Several types of testing were employed to evaluate the bactericidal efficacies of the coated substrates. Five of the coatings on circular glass cover-slips (12 mm diameter) were challenged with the bacterium Staphylococcus aureus (ATCC 6538). This was accomplished by adding a 50- jlL suspension of 10 CFU S. aureus to the surface of each sample. At predetermined contact times a 25- jlL aliquot was removed from the surface, quenched with sterile 0.02 N sodium thiosulfate, and plated on nutrient agar. The viable bacterial colonies were then counted after 48 h incubation at 37°C. Fabric samples were tested by two methods. In one, small squares (1.0-1.5 cm) were placed on a Tryptic Soy agar plate that was inoculated... 

A new treatment process for food sterilization involving a combination of heat and sonication under pressure has been reported [44], This methodology was found to decrease the heat resistance of Staphylococcus aureus by 63% and Bacillus subtilis by 43% as compared to heat treatment alone. This effect decreased with increase in temperature towards boiling point due to the fact that cavitational collapse becomes much less violent at these temperatures. Under pressure the boiling point is raised and lethality of the microbes above boiling point is maintained with values 5 to 30 times greater than those achieved with heat treatment alone. Spores appeared to be most resistant and yeasts the most susceptible to this type of treatment. 

It is a commonly held view that all bacteria are harmful but it is just not the case. Of course, pathogenic organisms such as methycillin resistant Staphylococcus aureus (MRSA), E. coli 0157 and many others are harmful to humans but the vast majority, e g., intestinal tract and waste breakdown organisms, animal rumen bacteria, are essential to us. Additionally, there is strong evidence that children acquire resistance to disease and illnesses such as asthma by exposure to microorganisms when they are very young. We would not survive in a sterile environment. 

Standard strains of Staphylococcus aureus (IF012732) and Escherichia coli (IF03972), cultured in SCD agar, and a lO cfu/mL bacterial solution was prepared using 10% glycerol solution. The bacterial solution was diluted 10 times with a 100 mmol/L phosphate buffer (pH 7 or pH 10). Each plant extract was added to the solution, and the final concentration was 0.25%. These mixtures were incubated at 37 C for 24 h. After the incubation period, the reacted mixtures were again diluted with fresh SCD broth on a 96-well plate. These plates were then incubated at 37 C for 2 days. The turbidity (595 nm) of the broth in the plate was measured with a plate reader (Spectra image, Tecan, Austria), and the number of sterilized cells were estimated. We were able to define the antimicrobial materials that were able to sterilize over 10 cfu/mL of the bacteria used in this procedure. 

A 100 mg sample of each coating was cut into small pieces, sterilised by UV light, and then dispersed in 9 ml of sterile saline water (0.85 wt%). 1 ml of bacterial (Escherichia coli or Staphylococcus aureus) culture (10 CFU/ml) was subsequently added to this solution and finally the concentration of polymer in the suspension was diluted to reach 10 mg/ml. The flasks were shaken at 90 rpm for 24 h and the temperature was maintained at 37 °C blanks without the coating were also run. The surviving bacteria before and after shaking were counted using the plate count method. 

The antibacterial activity of the fabric samples was tested using AATCC Method 100 using Staphylococcus aureus. The fabric swatch (l xl ) was placed in a sterilized flask containing Luria broth (Hi-media) solution, inoculated with 20 pi of test organisms and incubated at 37°C for 24 hrs in a laboratory shaker at 200 rpm. After incubation the number of colony forming unit (CFU) was counted by using serial dilution method. 

Sterility is the most important requirement concerning ophthalmic preparations. A diseased or injured eye is extremely sensitive to infections with catastrophic consequences. Pseudomonas aeruginosa is the most feared organism due to the organism causing serious and difficult to treat corneal ulceration, which can result in rapid loss of vision. Other bacteria such as Bacillus subtilis. Staphylococcus aureus and Haemophilis influenzae as well as yeasts and moulds such as Aspergillus fumigatus, Fusarium species and Candida albicans (or non-albicans) are responsible for serious eye infections. 

The bacterial penetration abihty in polymer sheets (BF and BL) was examined in presence of Staphylococcus aureus (S. aur) and Escherichia coli (E.coli) [7, 8]. The sheets were first cut into rectangular pieces of size 30 x 30 mm and placed on sterile nutrient agar medium in the petri dishes (diameter 85 mm). The open surface of each polymer sheet was contaminated with 0.02 ml of culture inoculums (10 CFU/ml) and then incubated at 37°C up to 120 hrs. Polymer sheets were removed every 24 hr interval and examined the formation of colony on the surface of nutrient agar plate where the ccaitami-nated sheets were placed. In each case, two specimens from the same sample were measured. 

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