Healthcare product manufacturers strive to provide safe, sterile products by validating and controlling manufacturing procedures. Validation study is the result of a multidisciplinary team effort. This successful effort relies on each discipline understanding the fundamentals of each technical disciplines and applying those fundamentals in terms of their own technical background. This paper is to introduce the basic concepts of sterilization methodology which are involved in validating various technical methods of sterilization and biological indicators (BIs). These will mainly address sterilization procedures in general terms and highlight on their microbiological aspects. The proper starting point is defining what sterility is and how it can be achieved through the validation studies by using BI.
Scallop shells are used to make food additives and plastering and paving materials. However, most of the shell is considered commercial waste. In scallop-harvesting districts, large numbers of shells are heaped near the seaside, which creates problems such as offensive odors and soil pollution from heavy metals that leach out of the viscera. Therefore, new applications for scallop shells need to be developed. The main component of scallop shells is calcium carbonate (CaCO3), which is converted to calcium oxide (CaO) when heated. Heated scallop shell powder (HSSP) possesses broad antimicrobial action against the vegetative cells of bacteria, spores, and fungi. HSSP applied to fresh vegetables and processed foods reduces the number of viable bacterial cells. The use of HSSP in food processing provides a source of minerals and prolongs the shelf life of foodstuffs. Moreover, reducing the amount of scallop shell waste would reduce the related pollution problem. This report is a review of the antibacterial activity of HSSP and its application for the control of microbes.
For microbial ecological analysis, 14 strains of Methylobacterium aquaticum isolated from water samples were subjected to clustering analysis on the basis of ribotyping and RAPD-PCR tests. The ribopatterns after digestion with EcoRI obtained from 14 strains of M. aquaticum were used to divide the strains into two groups (Groups I and II) with a similarity of 55%. From the analysis of RAPD patterns using primer 208, the 14 strains were divided into 3 groups (A-C) based on a homology of 45% or greater, and from that using primer 272, there were 4 groups (A-D) based on a homology of 50% or greater. The chlorine resistance (99.9% CT values) of these isolates was also experimentally confirmed, and we attempted to define the connection between chlorine resistance and the geno-cluster. The average CT value of group I was 0.89 mg•min/l and the average of group II was 0.69 mg•min/l. No remarkable differences in the CT values for the groups were found.
Viable bacteria and endotoxins in water sometimes cause problems for human health. Endotoxins are major components of the outer cell wall of gram-negative bacteria (lipopolysaccharides). In medical procedures, especially haemodialysis (HD) and related therapies (haemodiafiltration (HDF), haemofiltration (HF)), endotoxins in the water for haemodialysis can permeate through the haemodialysis membrane and cause microinflammation or various haemodialysis-related illnesses. To decrease such a biological risk, RO and UF membranes are generally used. Also, hot water disinfection or the chemical disinfection is regularly executed to kill bacteria which produce endotoxins. However, simple treatment methods and equipment may be able to decrease the biological risk more efficiently. In our experiments, we confirmed that viable bacteria and endotoxins were removed by Electro Deionization (EDI) technology and also clarified the desorption mechanisms.
The aim of this study was to evaluate the cytotoxicity of six ingredients used in eyedrops with regard to four corneoconjunctival cell lines. Cells were treated with the undiluted solution, and 2-fold, and 10-fold dilutions of each solution for 10, 30, and 60 min and cell viability was measured with the neutral red assay and the MTT assay. The degree of toxicity was based on the cell viability score (CVS). The CVS50 was determined by the number of measurements with a viability ≥ 50% of control. The CVS40/80 was calculated as follows: CVS40/80 = (number of measurements with a viability value >80%) - (number of measurements with a viability value <40%). Results were expressed as % of total measurements (%CVS). The results of each ingredient for %CVS50, and %CVS40/80 were 0.01% benzalkonium chloride (51, -13), 1% boric acid (100, 99), 0.4% methyl paraoxybenzoate (100, 100), 0.4% propyl paraoxybenzoate (100, 100), 1.0% polysorbate 80 (68, 18), and 0.5% chlorobutanol (100, 100). The use of benzalkonium chloride led to apparently low cell viability compared to the other five solutions.
The effect of sodium hypochlorite (NaOCl) on the decolorization of azo dye orange II (4-[(2-hydroxy-1-naphthalenyl) azo]-benzenesulfonic acid, monosodium salt) in aqueous solution was studied as a function of pH. The first-order rate constant of color reduction (k) was evaluated from the curve of color reduction in the initial stage of decolorization. The k values increased with increasing the pH from 5.4 to 9.3 and the NaOCl concentration from 2.82×10-4 M to 1.13×10-3 M. It was found that k depended on the concentration of OCl-, but not on HOCl. On the other hand, k decreased markedly at pHs more than 10, depending on pH. This suggested that the reactivity of the orange II molecule with OCl- decreased probably due to the competitive action of the hydroxide ion under alkaline conditions. It could be concluded that controlling the solution pH and the OCl- concentration was indeed a key factor determining the rate of decolorization of orange II in aqueous solution.