• Journal of Korean Ophthalmic Optics Society
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• v.19 no.1
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• pp.59-67
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• 2014

Purpose: The present study was aimed to compare the results of disinfection efficacy tested by membrane filtration method with dilution-neutralization method to develop the standard methods for evaluating disinfection efficacy of contact lens care products and to provide the result of disinfection efficacy of commercially available contact lens care products in domestic market. Methods: The results of disinfection efficacy against Staphylococcus aureus, Pseudomonas aeruginosa, Serratia marcescens, Candida albicans evaluated by membrane filtration method as a FDA standard and dilution-neutralization method as newly being a KFDA standard were compared and the disinfection efficacy of 16 multi-purpose solutions was further evaluated. Results: The disinfectants and contact lens care products having strong disinfection efficacy showed same results in both membrane filtration method and dilution-neutralization method. In case of contact lens care products having weak disinfection efficacy, the number of micro-organisms was not able to count since the colony was aggregated when evaluated by membrane filtration method. However, the number of micro-organisms was able to exactly count when evaluated by dilution-neutralization method. In addition, some commercially available contact lens care products did not meet disinfection standard and especially, their disinfection effect was often weak against Serratia marcescen and Candida albicans. Conclusions: It is concluded that dilution-neutralization method will be useful to evaluate disinfection efficacy since it is possible to count micro-organisms more precisely even with small amount of sample and check the results faster compared with membrane filtration method.

• Journal of Applied Biological Chemistry
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• v.49 no.3
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• pp.90-94
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• 2006

Bactericidal activity of grapefruit seed extract (GSE)-based disinfectant, as a safe disinfectant, was measured against five bacteria by Korean Food & Drug Administration (KFDA) dilution-neutralization method. GSE-based disinfectant showed a 99.9999% bactericidal activity against Escherichia coli ATCC 10536, Salmonella typhi ATCC 29629, Staphylococcus aureus ATCC 6538, Bacillus cereus ATCC 11778, and Listeria monocytogenes ATCC 1911 at the concentration of 2.15% GSE. It showed better bactericidal activity against Gram-negative bacteria of E. coli ATCC 10536 and S. typhi ATCC 29629 at lower concentration of GSE (0.43%). Based on the results, it was suggested that a possible bactericidal mechanism of GSE active ingredients was due to the abrupt osmotic shift during the bactericidal activity test by KFDA method.

• Journal of Life Science
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• v.25 no.9
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• pp.1036-1042
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• 2015

By using effective sanitizers, early block for transmission of pathogens is the effective way to prevent epidermic outbreaks. Here we developed a chlorine oxide bubbling type of sanitizing tablets and evaluated the disinfectant and sanitization effects. The sanitizers showed 99.999% of sanitization effect for Escherichia coli ATCC 10536 and Staphylococcus aureus ATCC 6538 strains for 5 min±10 sec on 20±1℃ in clean condition by dilution-neutralization method. It reduced more than 5 log₁₀ cfu/ml of a legal permission standard of colony reduction. When a few used socks and underwear soaked for one hour in the 0.1% of the sanitizing tablets, no microorganisms were grown on CHROMagar plates. However, on CHROMagar plates of the no sanitizing tablets treated control, about 6.5×10⁴ cfu/ml of Staphylococcus sp., Klebsiella sp. and Enterococus sp. were grown. Furthermore, the sanitizing tablets killed approximately 1.5x10⁸ cfu/ml of E. coli BL21 in 5 minutes. Therefore, we concluded that the chlorine based bubbling type of sanitizing tablets satisfied the legal standard for the regulation of food and drug safety for disinfectants and sanitizers to pathogens and daily supplies.

• Korean Journal of Veterinary Research
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• v.34 no.3
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• pp.517-527
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• 1994

An attempt was made to isolate a causative viral agents from the fecal specimens of the diseased dogs with the gastroenteritis symptoms. Two coronavirus-like agents were isolated by serial dilution end point method and plaque assay. The isolates were characterized in terms of cytopathology, antigenicity, replication, physicochemical and morphological properties. The results obtained through the experiment were as follows; 1. Among 7 fecal specimens collected from the dogs with enteric disease, 2(28.6%)coronavirus-like agents showing typical cytopathic effects of canine coronavirus were isolated, and designated as CCV D1 and CCV D2, respectively. 2. By the cross-neutralization test and indirect immunofluoresence antibody test, the isolates were antigenically indentified as the standard CCV. The viruses were replicated only in the cytoplasm of A-72 cells. 3. The isolates showed no haemagglutinating activity against the erythrocytes from 11 kinds of animals. 4. The electron microscopic observation for the isolates showed spherical and pleomorphic features, covered with club-shaped projections on the surface. The size of particles was ranged from 70 to 150nm. 5. In one-step growth curve for the isolates in A-72 cells, maximum titers of intracellular vius was $10^{4.6}$ $TCID_{50}/0.1ml$ at 46 hrs postinoculation(pi) of CCV Dl and $10^{4.4}$ $TCID_{50}/0.1ml$ at 34 hrs pi of CCV D2. The maximum titers of extracellular virus was $10^{5.5}$ $TCID_{50}/0.1ml$ at 58 hrs pi of CCV D1 and $10^{5.8}$ $TCID_{50}/0.1ml$ at 46 hrs pi of CCV D2. 6. In physicochemical property test, the isolates were very sensitive to choroform and were found to be RNA virus. The viruses was stable at pH 3.0 for 1 hr and at $22{^{\circ}C}$ for 5 hrs. However, infectivity titers reduced remarkably by treatment with $56{^{\circ}C}$ for 10min.