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Biomedical subjects

A D Russell

Publications and source records attributed to A D Russell.

At least 109 records · Page 6Linked to original sources
PubMed1993

Injury and repair in biocide-treated spores of Bacillus subtilis.

Bacillus subtilis NCTC 8236 spores exposed to appropriate concentrations of test biocides (glutaraldehyde, two iodine and two chlorine preparations) were able to repair injury if subsequently held in nutrient broth at 37 degrees C but not in broth at 22 degrees C, sterile filtered water at 4, 22 or 37 degrees C or germination medium at 37 degrees C. Repair appeared to occur primarily during outgrowth and was initiated soon for iodine-treated spores and latest for glutaraldehyde-treated ones.

Bacillus subtilis↗
PubMed1993

Antimycobacterial activity of 'Virkon'.

The peroxygen-based disinfectant, 'Virkon' (at concentrations of 2, 3 and 4%) was tested against Mycobacterium tuberculosis and M. avium-intracellulare over exposure times ranging between 30 and 120 min. Two test procedures were used: (a) a standard plate method, (b) a method incorporating the use of the 'Bactec' 460 radiometric system to chart bacterial growth following exposure to 'Virkon'. In our hands and under the conditions of the two test methods, 'Virkon' did not produce a satisfactory kill of the test strains over 60 or 120 min.

Disinfectants↗
PubMed1993

Revival of biocide-treated spores of Bacillus subtilis.

Spores of Bacillus subtilis NCTC 8236 were treated with biocides and then subjected to various revival procedures. Sodium hydroxide (optimum concentration 25 mmol l-1) revived a small portion of glutaraldehyde-treated spores but not of spores exposed to formaldehyde, polyvinylpyrrolidone-iodine (PVP-I), Lugol's iodine, sodium hypochlorite or sodium dichloroisocyanurate (NaDCC). Post-treatment heat shock (at 70 degrees or 80 degrees C) increased the numbers of colony-forming units (cfu) of formaldehyde-injured spores. Coat-extraction procedures had the greatest effect on iodine-pretreated spores. The uptake of iodine and chlorine was more rapid and occurred to a greater extent with outgrowing, germinating and especially coat-deficient spores than with mature, resting spores.

Antiviral Agents↗
PubMed1993

Revival of Bacillus subtilis spores from biocide-induced injury in the germination process.

Spores of Bacillus subtilis NCTC 8236 were treated with glutaraldehyde, Lugol's iodine, polyvinylpyrrolidone-iodine (PVP-I), sodium hypochlorite or sodium dichloroisocyanurate (NaDCC). After exposure survivors were enumerated on nutrient agar containing potential revival agents (subtilisin, lysozyme, calcium dipicolinate, calcium lactate). Of these, only calcium lactate had any significant enhancing effect and then only with iodine-treated spores. Calcium lactate (9 mmol l-1) in nutrient broth enhanced the rate and extent of germination of iodine-treated spores but not of spores previously subjected to glutaraldehyde, hypochlorite or NaDCC.

Bacillus subtilis↗
PubMed1993

Effects of chlorhexidine diacetate and cetylpyridinium chloride on whole cells and protoplasts of Saccharomyces cerevisiae.

Chlorhexidine diacetate (CHA) and the quaternary ammonium compound, cetylpyridinium chloride (CPC), were fungicidal to Saccharomyces cerevisiae A364A and CHA to its mannoprotein mutant LB6-5D. Both CHA and CPC induced leakage of K+ and pentose material from both strains and both agents induced protoplast lysis as well as interacting with crude cell sap. Differences were observed between CHA and CPC in protoplast lysis and in cell sap interaction. Q25 values for A364A with CHA as test agent were 5.6 and 1.6 (fungicidal activity, depending on method of calculation), 1.46 (cell sap interaction) and 0.77 (leakage of pentoses). A sub-lytic concentration of CHA reduced considerably protoplast regeneration. Although the plasma membrane is an important target site for both agents, interaction with other cellular components also contributes to fungal death.

Cetylpyridinium↗
PubMed1993

Conditions suitable for the recovery of biocide-treated spores of Bacillus subtilis.

Various factors were studied in order to determine the optimum conditions for the recovery of Bacillus subtilis spores treated with two iodine preparations, two chlorine-releasing agents or glutaraldehyde. The composition of the recovery medium was not usually important except that counts on brain heart infusion agar were significantly lower than on other media for iodine-treated spores. The addition to recovery media of soluble starch, charcoal, D-glucose or yeast extract usually had no discernible beneficial effect on colony counts. Maximum counts of survivors were obtained after an incubation period of 3 days and an optimum incubation temperature of 30 or 37 degrees C. Germination and outgrowth of biocide-exposed spores were more sensitive to changes in incubation temperature than were control spores.

Anti-Bacterial Agents↗
PubMed1992

The nature and site of biocide-induced sublethal injury in Bacillus subtilis spores.

Spores of Bacillus subtilis NCTC 8236 exposed at 22 degrees C to test biocides (alkaline glutaraldehyde, an iodophor, Lugol's solution, sodium hypochlorite and sodium dichloroisocyanurate) demonstrated varying degrees of injury to stressing agents (sodium hydroxide, sodium lauryl sulphate, polymyxin B sulphate or cetylpyridinium chloride) incorporated into a recovery agar medium. This injury to stressing agents was expressed mainly during outgrowth.

Bacillus subtilis↗
PubMed1992

Effects of chlorhexidine diacetate on Candida albicans, C. glabrata and Saccharomyces cerevisiae.

The effects of chlorhexidine diacetate (CHA) on Candida albicans, C. glabrata and wild-type and mannan, and permeability mutants of Saccharomyces cerevisiae have been studied. A CHA concentration of 10 micrograms/ml had little lethal activity against the Candida strains, but was more effective against S. cerevisiae. Concentrations of 100 and especially 1000 micrograms/ml brought about a much more rapid death of cells. 2-Mercaptoethanol enhanced the activity of CHA to some extent. Some of the mutant strains of S. cerevisiae were rather more sensitive than the wild-type strain. The age of cultures of C. albicans and C. glabrata influenced their response to CHA.

Candida↗
PubMed1992

Mechanism of action of chlorhexidine diacetate and phenoxyethanol singly and in combination against gram-negative bacteria.

Chlorhexidine diacetate and the aromatic alcohol, phenoxyethanol in combination had an enhanced bacteriostatic action against Escherichia coli and Pseudomonas aeruginosa strains. Investigations of potassium (K+) ion leakage by means of a potassium electrode and a radioactive method, employing 86Rb, indicated that the combination accelerated the rate of leakage from the cell. Leakage of pentose was also found to be enhanced in the presence of the combination compared with either drug alone.

Anti-Infective Agents, Local↗
PubMed1992

Bacterial uptake of 14C-chlorhexidine diacetate and 14C-benzyl alcohol and the influence of phenoxyethanol and azolectin: studies with gram-negative bacteria.

The uptake of 14C-chlorhexidine (14C-CHA) by Pseudomonas aeruginosa and smooth, rough and deep rough strains of Escherichia coli was very rapid with maximum uptake occurring within 20 s. Despite the rapid binding, the lethal action of CHA, although concentration-dependent, is comparatively slow and occurs in minutes rather than seconds. This indicates that the initial rapid binding is followed by a second slower action, responsible for the lethal effects of CHA. The lethal action could be accelerated, particularly at modest concentrations of CHA, by the simultaneous presence of phenoxyethanol (POE) or benzyl alcohol (BZA), although the magnitude of the effect was small. Both alcohols had little effect on the binding of 14C-CHA, which does not explain the enhanced bactericidal action of CHA. Uptake of 14C-benzyl alcohol (14C-BZA) by the same strains showed very different patterns with slower and time-related binding. CHA had a marked effect on BZA absorption but no direct link was established between binding patterns and cell death. The CHA neutraliser, azolectin, removed bound CHA (in the presence or absence of POE) very efficiently even at contact times of only 20 s.

Anti-Infective Agents, Local↗
PubMed1991

Factors affecting conjugative transfer of plasmid pWG613, determining gentamicin resistance, in Staphylococcus aureus.

Factors that are known to influence plasmid transfer in bacterial populations were studied for the conjugative plasmid pWG613, which determined gentamicin resistance in Staphylococcus aureus. The transfer frequency was largely unaffected over a wide range of temperature (18-42 degrees C); pH also had little effect on the transfer frequency in the range 5.0-8.5. High cell density and log phase cultures were required for optimal plasmid transfer, as were donor:recipient ratios of 0.003-3.3.

Cetrimonium↗