Bactericidal effect of pyridine-2-thiol 1-oxide sodium salt and its complex with iron against resistant clinical isolates of Mycobacterium tuberculosis

The objective of this study was to determine the activity of pyridine-2-thiol 1-oxide sodium salt (Na mpo) and its complex with iron [Fe(mpo)3] against Mycobacterium tuberculosis. The compounds were tested against a standard strain of M. tuberculosis H37Rv (ATCC 27294), with minimal inhibitory concentrations (MIC90) of 7.20 and 1.07 μM to Na mpo and [Fe(mpo)3], respectively, and against three clinical isolates with different genotypic profiles, with MIC values ranging from 0.74 to 6.52 and 0.30 to 2.25 μM to Na mpo and [Fe(mpo)3], respectively. [Fe(mpo)3] was more effective against susceptible strains but both compounds were effective in inhibiting MDR and XDR-TB clinical strains. The profile activity was determined through the methodology of a time-kill curve against standard and clinical strains of M. tuberculosis. Time-kill studies indicated that Na mpo had an early bactericidal activity against H37Rv and clinical isolates, with sterilizing effects observed in 5 and 7 days, respectively, at its MIC90. The anti MDR and XDR-M. tuberculosis activity and bactericidal effect of Na mpo and [Fe(mpo)3] demonstrate their potential as new compounds for the treatment of tuberculosis.