Efficacy of selected disinfectants against mycobacteria and cryptosporidia.

We have tested the in-vitro efficacy of various disinfectants against clinical isolates of Mycobacterium tuberculosis, Mycobacterium avium-intracellulare, and against the protozoon Cryptosporidium parvum. The disinfectants were tested both with and without an organic load. 'Sactimed sinald' (a quaternary ammonium compound), 'Steris 20' (a peracetic acid compound) and 'Pentapon DC1' (a beta-ene compound) were all equally as effective as 'Cidex' (glutaraldehyde) against all the mycobacteria tested, as well as C. parvum. 'Virkon' (a per-oxygen compound) and 'Phoraid' (an iodine compound) were less effective than glutaraldehyde. 'Pentapon DHY' (a beta-ene compound) was ineffective against any of the organisms tested. We have also assessed a method of determining disinfectant efficacy using [35S]-methionine labelling of proteins, which appears promising, although it requires further evaluation.