ABSTRACT
The preservative efficacy of both 'Betnovate' and 'Synalar' creams diluted 1:1 with 'Unguentum Merck' was investigated. Each formulation was challenged with Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa at an initial inoculum level of approximately 1 X 10(6) viable organisms per gram of cream. All formulations tested were found to be effectively preserved against the organisms used and no viable bacteria were detected 7 days after inoculation.
Subject(s)
Bacteria/drug effects , Betamethasone Valerate/pharmacology , Betamethasone/analogs & derivatives , Fluocinolone Acetonide/pharmacology , Pharmaceutic Aids/pharmacology , Preservatives, Pharmaceutical/pharmacology , Escherichia coli/drug effects , Ointments , Pseudomonas aeruginosa/drug effects , Staphylococcus aureus/drug effectsABSTRACT
The effect of dilution and temperature on the antibacterial properties of potassium sorbate was determined. The time taken to kill a standard inoculum of Escherichia coli was increased considerably after either dilution of the preservative or lowering of the temperature. The value for the concentration exponent, eta, was approximately 3 and that for the temperature coefficient, Q10, was 2.3.
Subject(s)
Anti-Bacterial Agents/pharmacology , Bacteria/drug effects , Fatty Acids, Unsaturated/pharmacology , Sorbic Acid/pharmacology , Temperature , Regression AnalysisABSTRACT
Aspects of the mode of action of three antibacterial agents, N,N'-bis (dodecyldimethyl)-1,2-ethane diammonium dibromide (BDED), 2-piperidinoethyl-4-heptyloxyphenylcarbamate hydrochloride (XXI) and 1-dodecylpiperidine N-oxide (DPNO) against Staphylococcus aureus have been examined. Their ability to modify respiration, proton translocation, potassium leakage and ATP synthesis are reported. In all cases there was a striking correspondence between the minimum inhibitory concentration and the dose level which completely prevented ATP synthesis. It is suggested that for these three chemically distinct molecules, bacteriostasis can be equated to a loss of the cell's ability to synthesize ATP, which, in turn, may stem from an uncoupling of oxidative phosphorylation.
Subject(s)
Cyclic N-Oxides/pharmacology , Phenylcarbamates , Piperidines/pharmacology , Quaternary Ammonium Compounds/pharmacology , Staphylococcus aureus/drug effects , Adenosine Triphosphate/biosynthesis , Cell Membrane Permeability/drug effects , Dose-Response Relationship, Drug , Hydrogen/metabolism , Oxygen Consumption/drug effects , Potassium/metabolism , Staphylococcus aureus/metabolismSubject(s)
Disinfectants/history , Air Microbiology , Anti-Infective Agents, Local/history , Anti-Infective Agents, Local/pharmacology , Disinfectants/pharmacology , History, 18th Century , History, 19th Century , History, 20th Century , Microbial Sensitivity Tests/history , Microbial Sensitivity Tests/methodsABSTRACT
Phenols were first isolated in crude form at the end of the eighteenth century. Pure phenol was isolated in 1834 and its structure proved in 1842. In 1860 Küchenmeister first used phenol as a wound dressing in Germany. Lister was to use it in his classical experiments in antiseptic surgery. Substituted phenols, and to some extent phenol itself, are still in use today as antiseptics, disinfectants and preservatives.
Subject(s)
Anti-Infective Agents/history , Phenols/history , Anti-Infective Agents/therapeutic use , Chemistry , France , Germany , History, 18th Century , History, 19th Century , History, 20th Century , Phenols/isolation & purification , Phenols/therapeutic use , United KingdomABSTRACT
Resistance of micro-organisms to antibacterial drugs which cannot be attributed to a genetic change may often be traced to phenotypic changes in cell composition caused by differing growth conditions. To investigate an aspect of this attribute E. coli NCTC 86 was grown on a simple synthetic media containing alanine or cystine and, as a control, in nutrient broth. Cells grown on the media containing alanine and cystine showed a depleted total extractable lipid and phospholipid content. Phosphatidylethanolamine was notably reduced in both cases. Electrophoretic studies revealed a reduction in the surface lipid of cells grown on the simple synthetic media, while electron microscopy revealed defects in the cell wall of the cells grown on alanine. The total protein content of cells grown on alanine was reduced, whereas cells grown on the cystine showed an enhanced total carbohydrate content. Lipopolysaccharide synthesis was possibly also affected as judged by 2-keto-3-desoxy-D-manno-octonic aid content. The action of p-tertiary amylphenol, cetrimide and polymyxin B sulphate, showed that cells grown on the media containing alanine were most susceptible to the action of the phenol and cetrimide, whilst cells grown on the media containing cystine were most resistant to the action of polymyxin.
