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Mycobactericidal activity of selected disinfectants using a quantitative suspension test
P A Griffiths1, J R Babb, A P Fraise
1Hospital Infection Research Laboratory, City Hospital NHS Trust, Birmingham.
The Journal of Hospital Infection
|March 4, 1999
Summary
Effective disinfectants against mycobacteria include peracetic acid, chlorine dioxide, alcohol, and high-concentration sodium dichloroisocyanurate. Glutaraldehyde is a slow-acting mycobactericide, while Gigasept and Virkon are not recommended for use where mycobacteria may be present.
Area of Science:
- Microbiology
- Infectious Diseases
- Public Health
Background:
- Mycobacteria, including *Mycobacterium tuberculosis* and non-tuberculous mycobacteria (NTM), pose significant infection control challenges in healthcare settings.
- Disinfection efficacy against mycobacteria varies greatly depending on the disinfectant and the specific mycobacterial species or strain.
- Endoscopes and medical instruments require rigorous disinfection to prevent transmission of healthcare-associated infections.
Purpose of the Study:
- To quantitatively assess the mycobactericidal activity of various disinfectants against clinically relevant mycobacteria under clean and dirty conditions.
- To compare the efficacy of disinfectants against different mycobacterial species, including *Mycobacterium chelonae*, *Mycobacterium fortuitum*, *Mycobacterium tuberculosis*, and *Mycobacterium avium-intracellulare* (MAI).
- To evaluate the performance of disinfectants used for instrument and environmental decontamination, including those used in washer-disinfectors.
Main Methods:
- A quantitative suspension test was employed to evaluate disinfectant activity.
- Tests were conducted under both clean and dirty conditions to simulate real-world scenarios.
- Disinfectants tested included sodium dichloroisocyanurate (NaDCC), chlorine dioxide, industrial methylated spirits (IMS), alkaline glutaraldehyde, succinedialdehyde/formaldehyde mixture (Gigasept), peracetic acid (NuCidex), and a peroxygen compound (Virkon).
Main Results:
- A clinical isolate of *Mycobacterium avium-intracellulare* (MAI) exhibited higher resistance to disinfectants compared to *Mycobacterium tuberculosis*.
- Type strains of *Mycobacterium chelonae* and *Mycobacterium fortuitum* were more sensitive to most disinfectants.
- An endoscope washer-disinfector isolate of *Mycobacterium chelonae* showed extreme resistance to alkaline glutaraldehyde and moderate resistance to Nu-Cidex, Gigasept, Virkon, and lower concentration NaDCC.
Conclusions:
- Peracetic acid (NuCidex), chlorine dioxide (Tristel), alcohol (IMS), and high concentrations of NaDCC demonstrated rapid mycobactericidal activity.
- Alkaline glutaraldehyde was effective but acted as a slow mycobactericide.
- Gigasept and Virkon were found to be poor mycobactericidal agents and are not recommended for use when mycobacteria are a concern.