Bactericidal activities of commonly used antiseptics against multidrug-resistant mycobacterium tuberculosis

Seventeen clinical isolates of Mycobacterium tuberculosis were selected in order to study the bactericidal activities against drug-resistant M. tuberculosis. The effects of different antiseptics against multidrug-resistant M. tuberculosis (MDR-TB) were examined. Each of the test strains was cultured on the surface of an agar slant containing Löwenstein-Jensen medium. 0.05 ml of the bacillary suspension was poured into a test tube, and 0.45 ml of various antiseptics was added. After the bacilli had been exposed to the antiseptic solution with 2% human serum for various periods of incubation time, the antiseptic was inactivated by addition of 0.45 ml neutralizer, a mixture containing 10% Tween 80, 3% soybean lecithin and 0.5% sodium thiosulfate. As the results, povidone-iodine (PVP-I) at a concentration of 0.2% killed 99.9% or more of all strains tested within 30 s. All of the strains tested with PVP-I were killed almost completely within 60 s. There was no difference in bactericidal activities of PVP-I between standard strain H37Rv and MDR-TB. 99.9% or more of all strains tested were killed after exposure to 1.0% cresol for 60 s. In the case of cresol however, the exposure time of 30 s was not enough to get satisfactory effects. 2.0% glutaraldehyde needed 5 min to kill 99.99% or more of the bacilli tested, and 0.2% alkyldiaminoethylglycine hydrochloride required 60 min to do so. The results of bactericidal activities of common antiseptics against MDR-TB were similar to those against H37Rv. We conclude that the commercially available PVP-I product is a useful antiseptic against MDR-TB similar to other M. tuberculosis.