Germicidal Efficiency Research Articles

N-Halo Derivatives V: Comparative Antimicrobial Activity of Soft N-Chloramine Systems

Comparative antimicrobial activity studies for certain new classes of soft N-chloramines derived from α-aminoisobutyric acid and 2-amino-2-methyl-1-propanol were examined using the minimum inhibitory concentration (MIC) and/or the contact germicidal efficiency (CGE) procedures. Several factors significantly influence the antimicrobial activity of the soft N-chloramines: (a) the aliphatic chain length in a homologous series, (b) the degree of chlorination of the nitrogen atom, (c) the solution pH, (d) the presence of a denaturant, and (e) the nature of a positive charge.

Advances in Chlorine‐Residual Analysis

Chlorine has historically been chosen for the disinfection of water supplies. Its germicidal efficiency and the long‐lasting effectiveness of chloramine residuals in the distribution system are responsible for its continued popularity. Unfortunately, techniques for continuous process analysis capable of differentiating between chlorine‐residual species and suitable for control are not fully appreciated. One such technique is presented in this article.

Bactericidal Effect of Low Concentrations of Silver

This article discusses experiments that found that the germicidal action of a specified amount of silver was related to the concentration of silver ions rather than to the physical nature of the silver from which the ions were originally derived. Neither the presence or absence of light nor the change in the density of test organisms within the range of 1,680 – 1,800,000 per milliliter produces a discernible effect on the bactericidal action of silver. Phosphate tends to decrease germicidal efficiency, whereas increases of pH accelerate death rates. Of the several neutralizers studied, a mixture of sodium thiosulfate and sodium thioglycollate was found to be most efficient. In the presence of inefficient neutralizers, bacteriostasis may be mistaken for bactericidal action. When silver‐contaminated glass is reused, some of the silver is desorbed and exerts a germicidal action. In these studies, boiling in sodium chloride solution was the most effective method of removing the silver from glassware. Radioactive Ag110m is useful in determining silver concentrations in solution and the residual remaining on surfaces.

A practical approach to evaluation of the germicidal efficiency of a general purpose military disinfectant.

The bactericidal activity of a general purpose disinfectant consisting of 25% sodium-o-phenylphenolate and 75% sodium-4- and 6-chloro-2-phenylphenolate was evaluated by a simulated in-use, surface-square dilution method. Common floor (asphalt, rubber, and unglazed tiles) and wall (stainless steel tile, ceramic tile, and painted wood) surfaces of various porosities and compositions were selected to simulate actual-use conditions. The method used consisted of inoculating the surfaces of 1-in. square sections of floor and wall covering with a test organism, air-drying the inoculated surface, applying the disinfectant, allowing it to act for 10 min, and recovering the survivors by plating. Confirmatory results of the standard phenol coefficient and use-dilution tests indicated 700 ppm of the disinfectant to be a safe use concentration. The in-use surface-square dilution studies have shown that this is a more than adequate safe concentration for stainless steel, both glazed and unglazed ceramic tile, and nonwaxed surface of asphalt tile. However, concentrations ranging between 2,500 and 6,000 ppm for plastic-fortified rubber tile, 1,500 and 2,000 ppm for waxed asphalt tile, and 2,000 ppm for painted wood were required to achieve 99.9% reduction of either Salmonella choleraesuis or Salmonella schottmuelleri. These results indicate that a disinfectant concentration derived from the Association of Official Agricultural Chemists use-dilution test cannot always be relied upon to provide a dependable index to actual safe use-dilution when a disinfectant is supplied to certain wall or floor surfaces.

Germicidal Efficiency of Egg Washing Compounds on Eggs Artificially Contaminated with Salmonella Typhimurium

SINCE the work of Pomeroy and Fenstermacher (1939), a number of workers (Pomeroy and Fenstermacher, 1941; Buxton and Gordon, 1947; Gregory, 1948) have found that Salmonella typhimurium and other paratyphoids can survive on chicken and turkey egg shells much longer than the normal incubation periods of 21 days for chickens and 28 days for turkeys. While numerous individuals have reported egg shell isolations of Salmonella species, Williams (1959) has summarized that reports of isolations of paratyphoids from egg contents or ovarian tissue are relatively uncommon. It is thus quite evident that one approach to any Salmonella control program, especially with reference to paratyphoids, would be an egg shell washing program designed to kill or remove Salmonella contamination. One standard practice already in effect is the routine formaldehyde fumigation practices of hatcherymen. Because of the fact, however, that such eggs may be several days to several weeks old before they are …

A Practical Approach to Evaluation of the Germicidal Efficiency of a General Purpose Military Disinfectant

The bactericidal activity of a general purpose disinfectant consisting of 25% sodium-o-phenylphenolate and 75% sodium-4- and 6-chloro-2-phenylphenolate was evaluated by a simulated in-use, surface-square dilution method. Common floor (asphalt, rubber, and unglazed tiles) and wall (stainless steel tile, ceramic tile, and painted wood) surfaces of various porosities and compositions were selected to simulate actual-use conditions. The method used consisted of inoculating the surfaces of 1-in. square sections of floor and wall covering with a test organism, air-drying the inoculated surface, applying the disinfectant, allowing it to act for 10 min, and recovering the survivors by plating. Confirmatory results of the standard phenol coefficient and use-dilution tests indicated 700 ppm of the disinfectant to be a safe use concentration. The in-use surface-square dilution studies have shown that this is a more than adequate safe concentration for stainless steel, both glazed and unglazed ceramic tile, and nonwaxed surface of asphalt tile. However, concentrations ranging between 2,500 and 6,000 ppm for plastic-fortified rubber tile, 1,500 and 2,000 ppm for waxed asphalt tile, and 2,000 ppm for painted wood were required to achieve 99.9% reduction of either Salmonella choleraesuis or Salmonella schottmuelleri. These results indicate that a disinfectant concentration derived from the Association of Official Agricultural Chemists use-dilution test cannot always be relied upon to provide a dependable index to actual safe use-dilution when a disinfectant is supplied to certain wall or floor surfaces.

Evaluation of germicidal efficiencies of a group of antibiotics tested by tissue culture technic.

SummaryA new method was proposed recently for the evaluation of germicides intended for clinical application. Iodine, with a toxicity index of 0.10 exhibited the greatest degree of germicidal efficiency. The same procedure was followed for the evaluation of a group of antibiotics. Penicillin G sodium gave an index of 0.0024 which indicated that it was more than 400 times more toxic to the test organism, Micrococcus pyogenes var. al-bus, than to the tissue cells, and approximately 42 times more efficient than iodine. Results on other antibiotics in order of decreasing efficiency are: Streptomycin sulfate, 0.02—; Polymyxin B sulfate, 0.63—, Terra-mycin, 0.67. Bacitracin and Chlorampheni-col were bacteriostatic and could not be evaluated. Likewise, Aureomycin HC1, Achro-mycin HC1, and Erythromycin could not be evaluated; the former two precipitated from solution shortly after being prepared, and the latter failed to dissolve in saline.

IODINE BACTERICIDES IN THE DAIRY INDUSTRY

A new development in dairy sanitation resulting from the combination of elemental iodine with non-ionic surfactants. The latter as carriers provide a solubilizing medium for the elemental iodine which favorably modifies the undesirable properties of iodine. The well-known germicidal efficiency of iodine is retained.The products, known commercially as IOSAN for dairy farm sanitation, and IOBAC for plant germicidal use, were thoroughly checked by laboratory and field tests to meet federal agencies, and state and municipality health department requirements.Both products have received a favorable reception by health authorities and the dairy industry.

The relationship of concentration and germicidal efficiency of ethyl alcohol.

The relationship of concentration and germicidal efficiency of ethyl alcohol.

A Study of the Germicidal Efficiency of Can Washing Compounds

A Study of the Germicidal Efficiency of Can Washing Compounds

347. The disinfection of contaminated metal surfaces with hypochlorite solutions

Tinned trays were artificially infected withStaphylococcus aureusin diluted milk and the dried surfaces disinfected by rinsing with sodium hypochlorite solutions.Under the conditions described, which we believe approximate those on many dairy utensils which have been imperfectly cleaned, thepH of hypochlorite solutions was found not to be a very important factor in determining their germicidal efficiency. AtpH 10 and 11, the solutions were equal to or slightly more efficient germicides than solutions at pH7.In the destruction of 99% of the organisms on the metal trays, a solution atpH 10, containing 200 p.p.m. available chlorine was about 7 times as rapid as one with 25 p.p.m. available chlorine.

STUDIES COMPARING THE SANITIZING EFFICIENCIES OF HYPOCHLORITES AND QUATERNARY AMMONIUM COMPOUNDS

The germicidal speed of four quaternary ammonium compounds has been compared with that of two hypochlorites against Staphylococcus aureus, Bacillus panis (vegetative cells and spores), Micrococcus candidus, cheese starter organisms, Escherichia coli and Pseudomonas aeruginosa, using the glass slide technique originally devised for comparing chlorine sterilizing agents. Against the Gram-positive species, the quaternary compounds were generally more effective than the hypochlorites; against the Gram-negative species, the reverse held true. Cheese starter organisms were an exception, being killed faster by the hypochlorites. Three of the four quaternary compounds were closely comparable in efficiency, while the fourth was definitely slower. The hypochlorites responded much more readily to favourable adjustments in pH and temperature than did the quaternary compounds. Some bacteriostatic effect was observed with higher concentrations of all four quaternary compounds, but it is not believed that the results were significantly affected thereby. The glass slide technique appears to offer many advantages in the evaluation of the germicidal efficiency of products designed for sanitizing metal or glass surfaces in food processing plants.

The Effect of Agar upon the Germicidal Efficiency of the Quaternary Ammonium salts

To determine the effect of agar upon the germicidal potency of quaternary ammonium salts, 0.2 per cent agar was included in the germicide‐bacteria mixtures during the test period. Standard germicide tests without agar were included as controls. When the four quaternary ammonium salts were tested in the presence of 0.2 per cent agar, germicidal dilutions were much lower than germicidal dilutions in the absence of agar. The neutralization effect of agar probably accounts for this discrepancy. Standard tests for antiseptic potency call for evaluation of creams, ointments, powders, etc., by agar cup plate methods. It is evident that such procedures are inappropriate for preparations which contain quaternary ammonium germicides.

The Germicidal Efficiency of Emulsept and of Chlorine in Washing Dirty Eggs

The percentages of microorganisms killed with emulsept in these experiments for the same series of eggs are many times greater than the percentages of those killed when 100 ppm active chlorine was used. Experiments are in progress on other phases of this problem.

Increased Germicidal Efficiency of Iodine in the Presence of an Oxidation-Reduction System

Increased Germicidal Efficiency of Iodine in the Presence of an Oxidation-Reduction System

Factors Affecting Germicidal Efficiency of Chlorine and Chloramine

Factors Affecting Germicidal Efficiency of Chlorine and Chloramine George R. Weber, and Max Levine CopyRight*Based on data from laboratories of the Department of Bacteriology and the Engineering Experiment Station, Iowa State College, Ames, Iowa. Presented before the Engineering Section of the American Public Health Association at the Seventy-second Annual Meeting in New York, N. Y., October 13, 1943. https://doi.org/10.2105/AJPH.34.7.719 Published Online: August 29, 2011

Germicidal Potency and Tissue Toxicity of Surface Active Saline Mixture of Azochloramid

ConclusionsThe addition of sodium tetradecyl sulfate to Azochloramid increased the efficiency of the germicide for Staphylococcus aureus and decreased it for Eberthella typhosa. Since Staphylococcus aureus is likely to be the better test organism it may be concluded that the addition of wetter probably improved the germicidal efficiency of Azochloramid. Certainly the addition of wetter greatly improved Azochloramid by decreasing the concentration required to produce the same effect as germicide without wetter. This results in a considerably more potent and economical preparation.For purposes of comparison all germicides tested to date are included in Table II. The halogens gave the lowest toxicity indexes when tested against both Staphylococcus aureus (Gram positive) and Eberthella typhosa (Gram negative). Since Staphylococcus aureus is likely to be the better test organism the halogens were followed by the phenols, the silver compounds, the mercurials, and lastly the dyes in the order named.

Effect of Certain Organic Compounds on Germicidal Efficiency of Mercuric Chloride.

SummaryThe carbohydrates glucose, maltose, and sucrose produced no effect on the germicidal efficiency of mercuric chloride. The concentration required to kill Staphylococcus aureus was the same wh...

Effect of Oxidation-Reduction on Germicidal Efficiency of Some Metallic Salts

SummaryInorganic metallic salts, which are not germicidal or only slightly so, may exhibit a pronounced killing effect when mixed in certain combinations and proportions. In order that increased germicidal action may occur the salts must be mixed to produce an oxidation-reduction system. The phenomenon is a function of the positive metallic ions; the negative ions apparently play no part in the reaction. In a later paper it will be shown that the phenomenon is not limited to inorganic compounds only but may be applied to mixtures of inorganic salts and organic compounds.

Yeast Extracts to Overcome Depressant Effects of Germicide on Skin Respiration

SummaryOne percent of an aqueous-alcoholic yeast extract protects rat skin against the toxic effects of phenylmercuric nitrate in a dilution of 1 :100.000 as determined by respiration measurements. A similar amount of yeast extract does not impair the germicidal efficiency of phenylmercuric nitrate against S. aureus in dilutions as low as 1 :500,000 under the test conditions. Protection of host tissue against toxic action of germicides with maintenance of germicidal properties is thus suggested.