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Biomedical subjects

A D Russell

Publications and source records attributed to A D Russell.

At least 127 records · Page 7Linked to original sources
PubMed1991

The effects of some halogen-containing compounds on Bacillus subtilis endospores.

Sodium hypochlorite (NaOCl) and sodium dichloroisocyanurate (NaDCC) were more active against Bacillus subtilis 8236 spores in both viability and in germination and outgrowth studies than were polyvinylpyrrolidone-iodine (PVP-I) and Lugol's solution. Of the two chlorine compounds studied NaOCl proved to be the more active. The two iodine-containing compounds gave contrasting results with the Lugol's solution demonstrating increased antibacterial activity with increasing available iodine concentration. The antibacterial behaviour of PVP-I, however, reflected the more complex nature of aqueous iodine-surfactant mixtures. Initially, non-complexed iodine concentration (the active species) increased with increasing total available iodine concentration, resulting in increasing antibacterial activity. However, due to changes in the physical properties of the mixture, a maximum concentration of non-complexed iodine was reached so that a further increase in total available iodine resulted in a decrease in non-complexed iodine concentration and consequently a decrease in the antibacterial activity of the solution was observed. A greater inhibitory effect was observed in subsequent germination and outgrowth studies when spores were pre-treated with respective biocide than when untreated spores were added to germination media containing biocide at t = 0. This may reflect a combination of different contact times plus the neutralizing effect of the germination media on such halogen compounds.

Bacillus subtilis↗
PubMed1991

Comparative sensitivity to antibiotics and biocides of methicillin-resistant Staphylococcus aureus strains isolated from Saudi Arabia and Great Britain.

Methicillin-resistant Staphylococcus aureus (MRSA) isolated in Saudi Arabia and Great Britain were examined for susceptibility to antibiotics and biocides. The strains differed in their sensitivity patterns. None of the Saudi strains showed resistance to propamidine isethionate, but most of the British gentamicin methicillin-resistant Staph. aureus (GMRSA) strains were highly resistant to this compound and to some other nucleic acid-binding (NAB) compounds. Both groups showed a low level of resistance towards quaternary ammonium compounds (QACs), but resistance to these compounds was not associated with resistance to gentamicin in the Saudi strains. The aminoglycoside-resistant determinants were non-conjugative in these strains. Natural MRSA strains were good recipients for pWG613, but transferred this plasmid in reciprocal crosses at significantly lower rates.

Anti-Bacterial Agents↗
PubMed1991

Effect of some antibiotics and biocides on plasmid transfer in Staphylococcus aureus.

The effects of some antibiotics and biocides on the conjugative transfer of the Staphylococcus aureus gentamicin resistance plasmid pWG613 were investigated. Gentamicin and vancomycin were found to stimulate plasmid transfer frequency by 10- to 20-fold whereas methicillin and three inhibitors of protein synthesis each reduced it by various degrees. Most significantly, mupirocin inhibited plasmid transfer frequency by more than 1000-fold. All the biocides tested (cationic agents, sodium dodecyl sulphate and an organomercurial) reduced plasmid transfer.

Anti-Bacterial Agents↗
PubMed1990

Uptake of L-[14C]-alanine by glutaraldehyde-treated and untreated spores of Bacillus subtilis.

The effect of glutaraldehyde on the uptake of L-alanine, and subsequent germination, in spores of Bacillus subtilis NCTC 8236 was examined. Germination was induced by single amino acids, D-glucose and phosphate buffer at 37 degrees C. L-alanine was the best germinant of all amino acids tested. Pretreatment of spores with low concentrations of acid and alkaline glutaraldehyde inhibited subsequent germination, complete inhibition being observed at concentrations of 0.1% (w/v). This concentration also prevented the loss of heat resistance of spores placed in germination medium and exposed to 75 degrees C. Radioactive studies indicated that maximum uptake of L-alanine occurred after ca 30 min at 37 degrees C. Only 1.2% of available L-alanine was taken up during germination. Pretreatment of spores with glutaraldehyde did not interfere with L-alanine uptake at aldehyde concentrations up to 0.5% (w/v). However, this was significantly reduced at a glutaraldehyde concentration of 1.0% (w/v). Minimal differences were observed between acid and alkaline forms of the aldehyde. The results are discussed in terms of the mode of action of glutaraldehyde.

Alanine↗
PubMed1990

Sporicidal action of alkaline glutaraldehyde: factors influencing activity and a comparison with other aldehydes.

The sporicidal efficacy of glutaraldehyde (2% w/v) was investigated under various conditions. Numerous factors influenced its activity: method of spore production, inherent spore resistance characteristics, alkalination, storage time and storage temperature. The sporicidal action of 2% alkaline glutaraldehyde at room temperature was compared with that of other aldehydes and commercially available formulations. Cidex (glutaraldehyde) and Sporicidin (glutaraldehyde + phenol full strength) were the most effective, followed by 8% (w/v) formaldehyde and 10% (v/v) Gigasept, a formaldehyde-containing product. Five per cent (v/v) Gigasept and 10% (w/v) glyoxal also had good sporicidal activity, though that of Sporicidin (1:16) was poor. No activity was observed with 10% (w/v) butyraldehyde.

Aldehydes↗
PubMed1990

Bacterial spores and chemical sporicidal agents.

Bacterial spores are among the most resistant of all living cells to biocides, although the response depends on the stage of sporulation. The development of resistance to some agents such as chlorhexidine occurs much earlier in sporulation than does resistance to glutaraldehyde, which is a very late event. During germination or outgrowth or both, resistance is lost and the cells become as susceptible to biocides as nonsporulating bacteria. Mechanisms of spore resistance to, and the action of, biocides are discussed, and possible means of enhancing antispore activity are considered. The clinical and other uses of sporicidal and sporostatic chemical agents are described.

Disinfectants↗
PubMed1989

Alkali-induced revival of Bacillus spores after inactivation by glutaraldehyde.

Spores of Bacillus subtilis 168 were apparently fully inactivated by exposure to 2% (w/v) glutaraldehyde for 20 h but a few spores could be revived by further treatment with 10-100 mM NaOH. A similar effect was found with spores from a range of Bacillus species. A minimum concentration of 5% (w/v) glutaraldehyde was required to prevent the alkali-induced reactivation. The implications of these results for the use of glutaraldehyde as a sporicidal agent are discussed.

Aldehydes↗
PubMed1989

Uptake of 14C-chlorhexidine diacetate to Escherichia coli and Pseudomonas aeruginosa and its release by azolectin.

Uptake of 14C-labelled chlorhexidine diacetate (14C-CHA) by wild-type and envelope mutant strains of Escherichia coli and Pseudomonas aeruginosa was very rapid. Maximum uptake was observed within a contact time of 20 s with no additional binding on increased contact, and was concentration-dependent. In contrast to this rapid binding of 14C-CHA, bactericidal studies revealed that the lethal activity of low concentrations of unlabelled CHA was slow, although higher concentrations had a rapid effect. Comparison of a wild-type strain with its envelope mutants indicated that there was little difference in 14C-CHA uptake, in minimal inhibitory concentrations or in bactericidal activity. Azolectin was found to be an effective neutralising agent of biguanide action, but in in vitro agar tests and in reducing or removing the amount of 14C-CHA taken up by the cells.

Chlorhexidine↗
PubMed1989

Glutaraldehyde: its uptake by sporing and non-sporing bacteria, rubber, plastic and an endoscope.

Uptake of glutaraldehyde to bacterial spores, germinating and outgrowing spores, vegetative cells (sporing and non-sporing bacteria), various types of rubber, plastic and an endoscope was investigated. Escherichia coli NCTC 10418 exhibited greatest uptake, followed by Bacillus subtilis NCTC 8236 vegetative cells and Staphylococcus aureus NCTC 6571. Germinated and outgrowing B. subtilis spores adsorbed more glutaraldehyde than resting spores, but less than vegetative cells. Low concentrations of alkaline and acid glutaraldehyde increased the surface hydrophobicity and inhibited the germination of bacterial spores, the alkaline solution to a greater extent in both cases. Rubbers exhibited varying degrees of uptake and are listed in decreasing order of uptake: red rubber, fluorinated rubber (Vinescol), silicone rubber (Silescol), butyl rubber (Butyl XX). Polypropylene, the only plastic examined, was found not to adsorb any glutaraldehyde. The endoscope adsorbed more glutaraldehyde (per gram) than fluorinated rubber but less than red rubber. No damage was observed.

Aldehydes↗
PubMed1989

Possible mechanisms for the revival of glutaraldehyde-treated spores of Bacillus subtilis NCTC 8236.

Spores of Bacillus subtilis NCTC 8236 were exposed to 2% alkaline glutaraldehyde and subsequently subjected to various treatments in an attempt to revive injured spores. Treatment with alkali (sodium or potassium hydroxide or, to a lesser extent, sodium bicarbonate) proved to be most successful. Some revival was achieved after thermal treatment. No revival was obtained with lysozyme or with various types of coat-removing agents. Experiments designed to distinguish between germination and outgrowth in the revival process established that sodium hydroxide (optimum concentration, 20 mmol/l) added to glutaraldehyde-treated spores increased the potential for germination. In contrast, spores which had been allowed to germinate before exposure to low concentrations of glutaraldehyde and then to sodium hydroxide were inhibited at the outgrowth phase to a much greater extent than germinated spores treated with the dialdehyde without subsequent alkali exposure. The results overall are discussed in terms of the possible mechanism and site of action of glutaraldehyde and the practical implications and significance of its use as a sporicide.

Aldehydes↗
PubMed1988

Assessment of 'cold Sterilog glutaraldehyde monitor'.

A new monitor, used in conjunction with an ultraviolet spectrophotometric difference method to determine glutaraldehyde concentration was tested with 2% alkaline solutions of varying concentrations and pH. Glutaraldehyde solutions with a concentration below 1.6% were rejected by the monitor, which reflected deterioration of glutaraldehyde quite closely, but failed to yield satisfactory results with fresh 2% alkaline solutions.

Aldehydes↗
PubMed1988

Sensitivity of methicillin-resistant Staphylococcus aureus strains to some antibiotics, antiseptics and disinfectants.

The effects of antibiotics, antiseptics and disinfectants against some methicillin-resistant (MRSA) and methicillin-sensitive (MSSA) Staphylococcus aureus strains have been studied. The MRSA and MSSA strains were equally sensitive to phenols, esters of para(4)-hydroxybenzoic acid and chlorhexidine but MRSA strains were slightly more resistant to quaternary ammonium compounds and considerably more so to dibromopropamidine isothionate. Some MRSA strains were also resistant to phenylmercuric nitrate (but not another organomercurial, thiomersal), mercuric chloride and cadmium chloride. All MRSA strains produced beta-lactamase. Strains from the Royal Free Hospital, London were highly resistant to beta-lactam antibiotics, erythromycin, trimethoprim and tetracyclines but were sensitive to other antibiotics. One strain from the University Hospital of Wales, Cardiff was resistant to gentamicin but sensitive to tetracycline and trimethoprim.

Anti-Bacterial Agents↗
PubMed1988

Mechanism of resistance of Bacillus subtilis spores to chlorhexidine.

Chlorhexidine diacetate (CHA) was rather more sporicidal at 20 degrees C to urea-dithreitol-sodium lauryl sulphate (UDS)-treated spores of Bacillus subtilis NCTC 8236 than to urea-dithiothreitol (UDT)-treated or normal (untreated) spores. UDS spores adsorbed more CHA from solution than did the other two forms. No differences in hydrophobicity, as determined by hydrophobic interaction chromatography (HIC) or bacterial adherence to hydrocarbon (BATH), could be detected between the three spore types. Germinating spores took up much less CHA than did outgrowing spores. Germinating cells were considerably more hydrophobic, as measured by the BATH technique, than outgrowing cells or normal spores. Chlorhexidine diacetate increased the apparent hydrophobicity of the two latter forms, but this effect could be partially reversed by subsequent exposure to a non-ionic surfactant.

Bacillus subtilis↗
PubMed1987

Comparative susceptibility of hospital isolates of gram-negative bacteria to antiseptics and disinfectants.

The sensitivity of hospital isolates of Gram-negative bacteria to cationic antiseptics, mercuric chloride and two organomercury compounds has been measured. A comparison was made with laboratory strains of known sensitivity which acted as standards. All strains of Escherichia coli showed a uniformly high sensitivity to chlorhexidine diacetate; other organisms tended to be less sensitive to the biguanide. Quaternary ammonium compounds were less effective than chlorhexidine. Resistance to mercuric chloride was observed frequently, but there was little evidence of organomercurial resistance except in Pseudomonas aeruginosa isolates.

Anti-Infective Agents, Local↗
PubMed1987

Quenching of the antibacterial activity of chlorhexidine and benzalkonium by Letheen broth and Letheen agar in relation to wild-type and envelope mutant strains of gram-negative bacteria.

Letheen broth and Letheen agar have been investigated for their ability to act as neutralising and recovery media for wild-type and envelope mutants exposed to chlorhexidine diacetate and benzalkonium chloride. At high dilutions, untreated cells of the envelope mutant of Pseudomonas aeruginosa 799/61 were unable to produce colonies on Letheen agar. As a result of various procedures, it was concluded that dilution in Letheen broth and plating in Isosensitest agar was a suitable method for quenching cationic bactericides without harming the test strains, and that the increasing use of Gram-negative bacteria with outer membrane defects means that considerable care may be necessary in selecting media for evaluating bactericidal activity.

Benzalkonium Compounds↗