Mignon D. Johnston

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AIMS To develop a novel, rapid method for testing the ability of quenching agents to neutralize disinfectants. METHODS AND RESULTS Tests were performed to determine the suitability of different neutralizers for a range of disinfectants, using a new method based on the Bioscreen optical density analyser. Results showed that during disinfection tests,(More)
AIMS To gain a greater understanding of the effect of interfering substances on the efficacy of disinfection. METHODS AND RESULTS Current kinetic disinfection models were augmented by a term designed to quantify the deleterious effect of soils such as milk on the disinfection process of suspended organisms. The model was based on the assumption that(More)
AIMS To examine the effect on the leakage of low molecular weight cytoplasmic constituents from Staphylococcus aureus using phenolics singly and in combination, and to see if the observations could be modelled using a non-linear dose response. METHODS AND RESULTS The rate of potassium, phosphate and adenosine triphosphate leakage was examined in the(More)
The aim of this study was to evaluate the efficacy of hydrogen peroxide vapour (HPV) against spores of Clostridium botulinum, for use as a method for decontaminating environments where this pathogen has been handled. Spores were dried onto stainless steel slides and exposed to HPV in a sealed glovebox enclosure, transferred to a quenching agent at timed(More)
A new method is described for screening potential biocides based on the traditional suspension test using the Bioscreen optical plate reader. This new method is rapid, reproducible, quantitative and cost effective. Data obtained by this new method are not directly equivalent to the log reduction normally quoted, but give a measurement of the total effect of(More)
We present observations of both null and non-null SKS splitting from temporary deployments across the southeastern United States in order to evaluate the relative contributions of lithospheric deformation and asthenospheric flow to regional anisotropy. Data for this study come from four temporary broadband seismic deployments: the Appalachian Seismic(More)
Disinfection kinetic studies of sodium dodecyl sulphate, benzalkonium chloride and sodium hypochlorite against Staphylococcus aureus revealed that when a higher inoculum level of Staph. aureus than normal was used (approximately 1 log higher), the efficacy of disinfection was severely attenuated. Kinetic analysis using the Hom model for experiments carried(More)
AIMS To induce pathogenic Vibrio bacteria into a changed physiological state, in response to cold temperatures in sea water, and assess their sensitivity to heating and freezing, as compared with normal cells. METHODS AND RESULTS Cells of exponential phase Vibrio vulnificus, V. cholerae and V. parahaemolyticus were washed and inoculated into flasks of sea(More)
AIMS To demonstrate the effect that non-linear dose responses have on the appearance of synergy in mixtures of antimicrobials. METHODS AND RESULTS A mathematical model, which allows the prediction of the efficacy of mixtures of antimicrobials with non-linear dose responses, was produced. The efficacy of antimicrobial mixtures that would be classified as(More)