Evaluation of Povidone-Iodine and Chlorhexidine against Outbreak and Nonoutbreak Strains of Mycobacterium abscessus Using Standard Quantitative Suspension and Carrier Testing.

Povidone-iodine (PI) and chlorhexidine (CHX) are widely used antiseptics active against conventional , , species, and viruses, but their efficacy against remains unproven. We determined the potency of alcoholic PI and CHX against subsp. (ATCC 19977), subsp. (BCRC 16915), and our outbreak strain of subsp. (TPE 101) in reference to (ATCC 29213) by standard quantitative suspension and carrier methods (EN 14563). By suspension, all mycobacterial strains compared to were significantly more resistant to CHX, but not PI. By carrier, the mean logarithmic reductions (LR) achieved by PI under clean (dirty) conditions were 6.575 (2.482), 5.540 (2.298), 4.595 (1.967), and 1.173 (0.889), while those achieved by CHX under clean (dirty) conditions were 3.164 (5.445), 5.307 (2.564), 3.844 (2.232), and 0.863 (0.389) for , subsp. , subsp. , and subsp. , respectively. subsp. (outbreak strain) was significantly more resistant than the other tested strains to PI and CHX. By both methods, the mean LR achieved by PI was higher than for CHX for all mycobacterial strains, but under dirty conditions, neither antiseptic was effectively mycobactericidal (LR < 5). These preliminary findings caution against the universal replacement of PI with CHX as the first-line skin antiseptic, since all isolates were resistant to CHX. More studies are needed to establish the best practice for skin antisepsis if mycobacterial infections are also to be prevented.