[Inactivation of mycobacteria by disinfectants with a tuberculocidal label]

Abstract

Introduction: Disinfectants available in Venezuela, registered as tuberculocidal, and used in clinical and laboratory settings were tested for their mycobactericidal activity.

Methods: The European Standard Quantitative Suspension test prEN14348 was used in simulated clean and dirty conditions. The disinfectants tested included Gerdex and K-ller (both containing the quaternary ammonium compound dimethyl benzyl lauryl ammonium bromide in concentrations of 10% and 0.16% respectively), Microplus-Action (5% polymethylene urea), Cidex (2% glutaraldehyde) and Cidex OPA (0.55% ortho-phthalaldehyde). The mycobactericidal activity was evaluated with M. smegmatis ATCC 19420 and in clinical isolates of M. fortuitum, M. chelonae and M. abscessus. The tuberculocidal activity was assessed with M. tuberculosis H37Rv.

Results: Cidex and Cidex OPA were effective against all the test organisms, showing a > 5-log 10 reduction in CFU after 5 minutes of exposure under both clean and dirty conditions. Gerdex and K-ller only achieved a 2-log reduction in M. tuberculosis, M. abscessus and M. chelonae CFU, even after 60 minutes of exposure. Micro Plus Action showed a 4-log reduction in M. tuberculosis viability but less than a 1-log reduction in M. abscessus and M. chelonae CFUs after 60 minutes of incubation.

Conclusion: The tuberculocidal activity claimed by the manufacturers of several disinfectants sold in Venezuela, Gerdex, K-ller and Microplus-Action is inaccurate when tested by European norms. The use of these products for disinfecting material used in critical and semi-critical patients could result in iatrogenic infections.