Development of a Broad Spectrum, Sporicidal, Cost Saving Disinfectant Incorporating a Novel Antimicrobial Catalyst
Introduction: Hospital infections are still a major burden within the health care sector. Without adequate infection control procedures such as hand washing and disinfection, this can lead to morbidity and mortality in the extremely ill or immunocompromised patients. A novel heterogeneous polyacrylonitrile (PAN) fibre catalyst, produced by De Montfort University and impregnated with ferric sulfate has been previously shown to have potent antimicrobial activity against bacteria, when used in conjunction with hydrogen peroxide (H2O2). The aims of this research were to develop a sporicidal technology to help combat hospital acquired infections; develop a strong, flexible and absorbent catalyst for liquid and gaseous applications; establish the antimicrobial activity of the novel antimicrobial catalyst against bacteria using gaseous H2O2; and to establish the leachate antimicrobial activity. Methods: The Methods used were modified British Standard Suspension tests for basic sporocidal, bactericidal, mycobactericidal and yeasticidal activity. Ammonia testing was done using the Hach-Lange cuvette system, while hydrazine and hydroxylamine were tested using modified spectrophotometric tests. Iron was analysed using atomic absorption spectrophotometry. Modified membrane experiments were based on methods from Carson et al. (2002), Chen and Cooper (2002), Garcia et al. (2006) and Fisher and Philips (2009). Applications were tested using suspension tests, high pressure liquid chromatography (one-step application) or using the BioQuell, UK testing criteria (vaporised hydrogen peroxide). Results and Discussions: The PAN catalyst and H2O2 system had a significantly greater sporicidal, mycobactericidal and fungicidal activity, compared to H2O2 alone (p<0.05) which further increased when the catalyst to H2O2 ratio was increased (p<0.01). The leachate after one-use, in conjuncion with H2O2, was found to be equal in activity to the PAN catalyst and H2O2 system, with no significant difference (p>0.05) observed . Ammonia, hydrazine, hydroxylamine and iron were found to be leaching, suggesting that the pre-washing procedure needs to be optomised. However either alone, or in combination, these compounds were not found to contribute to the increase in antimicrobial activity. The activity of the ‘leachate’ was also found to diminish with re-use, whereas the PAN catalyst still retained the same antimicrobial activity (p>0.05) after 5 re-uses, confirming its heterogeneity. The PAN catalyst was found to lower the sub-lethal concentration of H2O2 alone, with the cytoplasmic membrane found to be a target for sub-lethal injury.When the PAN catalyst was present a greater increase in membrane permeability and decrease in membrane potential was observed, which also showed a loss of the cell’s ability to maintain intracellular pH. The applications of this system are diverese with the PAN catalyst showing promise in a one-step H2O2 system. The PAN catalyst and H2O2 system may also potentially reduce costs compared to H2O2 alone, therefore allowing shorter contact times and lower concentrations of H2O2 to be used.
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