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Ortho-phthalaldehyde: a possible alternative to glutaraldehyde for high level disinfection
S E Walsh1, J Y Maillard, A D Russell
1Welsh School of Pharmacy, Cardiff University, UK.
Abstract:
Ortho-phthalaldehyde (OPA) was tested against a range of organisms including glutaraldehyde-resistant mycobacteria, Bacillus subtilis spores and coat-defective spores. Glutaraldehyde (GTA) and peracetic acid (PAA) were tested for comparative purposes. Both suspension and carrier tests were performed using a range of concentrations and exposure times. All three biocides were very effective (> or = 5 log reduction) against Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa in suspension tests. OPA and GTA (PAA was not tested) were also very effective against Staph. aureus and Ps. aeruginosa in carrier tests. OPA showed good activity against the mycobacteria tested including the two GTA-resistant strains, but 0.5% w/v OPA was found not to be sporicidal. However, limited activity was found with higher concentrations and pH values. Coat-defective spores were more susceptible to OPA, suggesting that the coat may be responsible for this resistance. The findings of this study suggest that OPA is effective against GTA-resistant mycobacteria and that it is a viable alternative to GTA for high level disinfection.
Insights
Ortho-phthalaldehyde (OPA) effectively disinfects against glutaraldehyde-resistant mycobacteria, offering a viable alternative for high-level disinfection. However, OPA at 0.5% concentration was not found to be sporicidal.
Area of Science:
- Microbiology
- Infectious Diseases
- Disinfection and Sterilization
Background:
- High-level disinfection is crucial for preventing healthcare-associated infections.
- Glutaraldehyde (GTA) resistance in mycobacteria presents a significant challenge.
- Ortho-phthalaldehyde (OPA) is an alternative disinfectant with a different chemical mechanism.
Purpose of the Study:
- To evaluate the efficacy of ortho-phthalaldehyde (OPA) against a range of microorganisms, including glutaraldehyde-resistant mycobacteria.
- To compare OPA's performance with glutaraldehyde (GTA) and peracetic acid (PAA).
- To assess OPA's activity against bacterial spores, including coat-defective strains.
Main Methods:
- Suspension and carrier tests were conducted using various concentrations and exposure times.
- Organisms tested included Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, glutaraldehyde-resistant mycobacteria, and Bacillus subtilis spores.
- Comparative analysis with glutaraldehyde (GTA) and peracetic acid (PAA) was performed.
Main Results:
- OPA, GTA, and PAA demonstrated high efficacy (> or = 5 log reduction) against E. coli, S. aureus, and P. aeruginosa in suspension tests.
- OPA and GTA showed excellent activity against S. aureus and P. aeruginosa in carrier tests.
- OPA exhibited significant activity against GTA-resistant mycobacteria, but 0.5% OPA was not sporicidal; higher concentrations and pH showed limited sporicidal activity.
- Coat-defective spores were more susceptible to OPA, indicating the spore coat may confer resistance.
Conclusions:
- Ortho-phthalaldehyde (OPA) is effective against glutaraldehyde-resistant mycobacteria.
- OPA is a potential alternative to glutaraldehyde for high-level disinfection.
- Further research is needed to optimize OPA's sporicidal activity and understand resistance mechanisms.