Biological properties of Mycobacterium tuberculosis (Mtb) resistant to biocides

The problem of resistance of&nbsp;<i>Mtb</i> to antibiotics is a global threat to humanity. Along with drug resistance, <i>Mtb</i> can also develop resistance to other biocides (e.g. disinfectants), but this phenomenon is currently not well understood and became the goal of this study. <b>Materials and methods:</b> We studied 21 isolates of <i>Mtb</i> that are resistant to biocides and isolated from the surfaces of the TB hospital. Growth properties, virulence, genotype, spectrum of drug resistance and resistance to 4 classes of chemical disinfectants (chlorine, hydrogen peroxide, aldehyde containing and quaternary ammonium compounds (QACs)) were determined. Since surfactants account for up to 70% of all biocides in the disinfectant market, we present data only for this class of chemical compounds. Resistance mutations and genetic family were determined by TB-Biochip system. <i>Mtb</i> resistance to biocides were estimated following the UNE-EN 14348 standard and tissue test-object method. To study the virulence of <i>Mtb</i>, guinea pigs were infected with a dose of 1000 сfu in 0,1 ml. <b>Results:</b> All <i>Mtb</i> isolates were characterized by increased growth ability on the grow media and virulence in vivo experiments. 17 isolates belonged to the <i>Beijing</i> genotype; four isolates were mixed cultures of <i>Beijing</i> and <i>Ural</i> genotypes. 15 isolates (71.4%) were XDR <i>Mtb</i>, 6 (28.6%) were pre-XDR <i>Mtb</i>. When determining the minimum inhibitory concentration of QACs, the ability to grow was found in all <i>Mtb</i> isolates after exposure to a concentration 6-10 times higher than recommended for use. <b>Conclusions:</b> Thus, on the surfaces of the TB hospital, we found highly virulent <i>Mtb</i> of <i>Beijing</i> genotype, resistant to a wide class of the biocides and a high degree of TB drug resistance.