Disinfectant-susceptibility of multi-drug-resistant Mycobacterium tuberculosis isolated in Japan

Abstract

Background: Multi-drug-resistant Mycobacterium tuberculosis has been an important problem in public health around the world. However, limited information about disinfectant-susceptibility of multi-drug-resistant strain of M. tuberculosis was available.

Findings: We studied susceptibility of several Japanese isolates of multi-drug-resistant M. tuberculosis against disinfectants, which are commonly used in clinical and research laboratories. We selected a laboratory reference strain (H37Rv) and eight Japanese isolates, containing five drug-susceptible strains and three multi-drug-resistant strains, and determined profiles of susceptibility against eight disinfectants. The M. tuberculosis strains were distinguished into two groups by the susceptibility profile. There was no relationship between multi-drug-resistance and disinfectant-susceptibility in the M. tuberculosis strains. Cresol soap and oxydol were effective against all strains we tested, regardless of drug resistance.

Conclusions: Disinfectant-resistance is independent from multi-drug-resistance in M. tuberculosis. Cresol soap and oxydol were effective against all strains we tested, regardless of drug resistance.

Keywords: Disinfectant; Microbicide; Multi-drug-resistant Mycobacterium tuberculosis.

Fig. 1

Efficacy of disinfectants to M. tuberculosis stains. Each M. tuberculosis stain was exposed to the disinfectants for 1 min at room temperature. The bacteria were incubated in Middlebrook 7H9 broth for 14 days at 37 °C. Bacterial growth was measured by 16S rRNA targeted real-time qPCR. Control was not exposure by any disinfectants. Dashed line indicates the genome copy number on the day of inoculation. ADEG, alkyldiaminoethylglycine-HCl (0.2 % W/V); CG, chlorhexidine gluconate (0.1 % W/V); PI, povidine iodine (10 mg/ml as active iodine); BK, benzalkonium-HCl (0.1 % W/V); OX, oxydol (3 % W/V); CS, cresol soap (2 % V/V); EtOH, ethanol (70 % V/V); and BK + EtOH, benzalkonium-HCl (0.1 % W/V) + ethanol (70 % V/V). The results are expressed as means ± SD. *: p <0.05 (v.s. genome number on the day of inoculation). Black bars: the disinfectant inhibited growth of M. tuberculosis (effective disinfectant). White bars: the disinfectant did not inhibit growth of the bacteria (not effective)