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Biomedical subjects

A D Russell

Publications and source records attributed to A D Russell.

At least 91 records · Page 5Linked to original sources
PubMed1996

The use of an automated assay to assess phage survival after a biocidal treatment.

The coliphage K1-5 has been used in an automated assay to monitor the viricidal activity of various disinfectants. This indirect assay based on the spectrophotometric reading of the lysis of the host cell (Escherichia coli D837) produced encouraging results and was faster than the overlay counting method (previously studied) which relies on plaque formation. However, differences in sensitivity towards some disinfectants were observed between the two methods.

1-Propanol↗
PubMed1996

The lethal effects of biguanides on cysts and trophozoites of Acanthamoeba castellanii.

The effects of a range of biocides on trophozoite and encysted forms of Acanthamoeba castellanii were investigated. Viable acanthamoebae were enumerated by a plaque assay technique. The cyst form of Acanthamoeba castellanii was more resistant to all biocides tested than the trophozoite form. Of the biocides tested, chlorhexidine diacetate (CHA) and polyhexamethylene biguanide (PHMB) were the most effective. Their lethal effects were time- and concentration-dependent. CHA was very effective when formulated in 0.1% EDTA combined with Tris buffer pH 7.8 whereas PHMB activity was reduced by 0.1% EDTA. Three per cent dimethylsulphoxide (DMSO) enhanced the activity of CHA but not of PHMB.

Acanthamoeba↗
PubMed1996

Antibiotic and biocide resistance in bacteria.

Antibiotic-resistant bacteria pose an ever-increasing therapeutic problem. The ways whereby bacteria circumvent drug action are many and varied, ranging from intrinsic impermeability to acquired resistance (involving plasmids, transposons and mutations). Antibiotics may be unable to reach susceptible target sites, they may be enzymatically inactivated, modified or expelled or mutations may arise such as to render the target sites insusceptible. Mechanisms of bacterial resistance to biocides are less well understood but cellular impermeability is a major factor. Plasmid-mediated efflux of cationic antiseptics in antibiotic-resistant Staphylococcus aureus strains has been demonstrated but its role in the resistance of these organisms to the biocide concentrations used in clinical practice is unclear. An association between resistance to antibiotics and biocides in Gram-negative bacteria has also been observed but it is often difficult at present to reach definite conclusions about genetic linkages between antibiotic resistance and biocide resistance.

Anti-Bacterial Agents↗
PubMed1996

The possible role of yeast cell walls in modifying cellular response to chlorhexidine diacetate.

The relative porosity (RP) and thickness of cell walls of Saccharomyces cerevisiae depended upon the age of culture, the RP decreasing and the cell wall thickness increasing in older cultures. Chlorhexidine diacetate (CHA) produced cytological changes in S. cerevisiae cells, involving dense and granular cytoplasmic constituents, withdrawal of the interior from the cell wall and a general loss of the typical cellular organization. Cell wall mannan is unlikely to play a role in limiting the entry of CHA into yeast cells but changes in glucan composition, wall thickness and RP might be involved in determining the sensitivity of cells to the biguanide.

Anti-Infective Agents, Local↗
PubMed1995

Electronmicroscopic investigation of the effects of biocides on Pseudomonas aeruginosa PAO bacteriophage F116.

Electronmicroscopy was used to observe morphological changes of the Pseudomonas aeruginosa PA0 bacteriophage F116 when treated with various biocides commonly used as antibacterial and antifungal agents. Because of its large size (145 nm) and its organised structure (an isometric head and a tail), it was possible to classify structural damage into eight categories. The morphological changes induced depended on the type of biocide used and its concentration. Glutaraldehyde increased the number of phages with empty heads. Peracetic acid and phenol altered the appearance of the viral genome packaged inside the head, produced fractured heads, and damaged the tail. Peracetic acid also induced folding of the phage heads. The alcohols tested also altered the head structure. Cetylpyridinium chloride induced mainly fractured head damage. Chlorhexidine had little effect on the structure of F116.

1-Propanol↗
PubMed1995

Potentiation of the effects of chlorhexidine diacetate and cetylpyridinium chloride on mycobacteria by ethambutol.

Ethambutol enhanced the effects of chlorhexidine diacetate and cetylpyridinium chloride against Mycobacterium avium, M. bovis BCG, M. fortuitum and M. phlei. The findings show that it is possible to increase the susceptibility of mycobacteria to agents that normally exhibit poor activity against these organisms because of their reduced cellular penetration.

Anti-Infective Agents, Local↗
PubMed1995

A note on the development of a non-aldehyde fixation technique for examining spores of Bacillus subtilis under the electron microscope.

Various techniques were studied for fixing spores of Bacillus subtilis prior to examining them by transmission or scanning electron microscopy. A non-aldehyde technique employing carbodiimide in cacodylate buffer produced excellent results and could be of value in studying the cytological changes produced in spores exposed to inimical treatments.

Bacillus subtilis↗
PubMed1995

Uptake of 14C-chlorhexidine gluconate by Saccharomyces cerevisiae, Candida albicans and Candida glabrata.

Uptake of radiolabelled chlorhexidine gluconate (14C-CHG) to Saccharomyces cerevisiae, Candida albicans and C. glabrata was very rapid and near maximal within 30 s. The organism, S. cerevisiae, most sensitive to the lethal action of chlorhexidine, took up significantly more biocide than the other organisms. Cells from cultures of different ages took up different amounts of 14C-CHG.

Anti-Infective Agents, Local↗
PubMed1995

Effects of chlorhexidine gluconate on the development of spores of Bacillus subtilis.

The effects of sublethal concentrations of the membrane-active agent chlorhexidine gluconate (CHG) on the growth rate and sporulation of Bacillus subtilis vegetative MB2 cells have been investigated. CHG increased the mean generation time (Mgt) of vegetative cells in casein medium. It also affected spore development: as CHG concentrations increased, spore index (SI) values decreased and sensitivity to both toluene and heat increased.

Bacillus subtilis↗
PubMed1995

X-ray microanalysis of chlorhexidine-treated cells of Saccharomyces cerevisiae.

The use of energy dispersive analysis of X-rays (EDAX) to identify and quantify the presence of chlorhexidine diacetate (CHA) within Saccharomyces cerevisiae cells was examined. Chlorine was used as the elemental marker tag. Saccharomyces cerevisiae cells exposed to 1000 micrograms ml-1 CHA took up increasing amounts of CHA over a time period of 30 s to 30 min. Electron probe micro-analysis was employed to examine the specific accumulation of CHA across the treated cells. These results showed that CHA was distributed evenly between the cell wall, cytoplasm and vacuoles of cells pre-treated with this concentration of CHA for 30 min. The EDAX system therefore provides a useful tool for examining the qualitative and quantitative effects of chlorhexidine on yeast cells, although quantitative data must be interpreted with caution.

Chlorhexidine↗
PubMed1994

Antibacterial activity of Actisorb Plus, Actisorb and silver nitrate.

Activated Charcoal Cloth with silver (Actisorb Plus) and solutions of silver nitrate, but not Actisorb (Activated Charcoal Cloth without silver), demonstrated antibacterial activity against Gram-negative and Gram-positive bacteria. This activity was unimpaired in the presence of plasma. Sodium thioglycollate was an effective neutralizer of Actisorb Plus and of silver nitrate, indicating that the release of silver from Actisorb Plus contributed to the antibacterial activity of the dressing.

Charcoal↗
PubMed1994

Glutaraldehyde: current status and uses.

Glutaraldehyde (pentanedial) is a dialdehyde that displays potent bactericidal, fungicidal, mycobactericidal, sporicidal, and virucidal activity. Pertinent to its activity is its interaction with amino groups in proteins and enzymes, but this simplistic statement masks the manner in which it inactivates various types of microorganisms. Notwithstanding its toxicity for medical staff, glutaraldehyde remains an invaluable compound for high-level disinfection purposes in endoscopy units.

Bacteria↗
PubMed1994

Effect of Biocides on MS2 and K Coliphages.

Several biocides commonly used in disinfection processes as antibacterial and antifungal agents were tested for activity against MS2 and K coliphages. MS2 was resistant to most biocides; only glutaraldehyde (0.5%) and peracetic acid (1%) achieved a 4-log(10) titer reduction in 20 min. In contrast, K phage was sensitive to most biocides, being resistant only to phenol (2%) and chlorhexidine (1%).

Journal Article↗