Introduction: Susceptibility testing of new and repurposed anti-TB drugs in Georgia in 2020 demonstrated that, 28% of pre-XDR-TB cases had additional resistance to one of the most effective ?Group A? drugs.

The aim  of  the study was to investigate in vitro inhibitory effect of Moxifloxacin (Mfx) and silver nanoparticle (AgNPs ) composite on Mfx  resistant ( Mfx/R-TB) Mycobacterium tuberculosis  (MTB) strains.

Materials and Methods:  Standard dose of Mfx  and 20 nm AgNPs [of 6 different concentrations: 0.25%; 0.5%; 1%; 2.5%; 5%; 10%] were added to already grown 40 resistant Mfx/R-TB cultures. The control group consisted of 35 Mfx/R isolates, to which only solutions of AgNPs of identical concentrations were added. The inhibitory effect of different concentrations of Mfx  and AgNPs was evaluated according to MTB growth rate using the BACTECTM MGIT 960TM TB System.

Results: In vitro usage of nanocomposite with  standard dose of Mfx and 20 nm  2.5% AgNPs  solution showed minimal inhibitory effect on Mfx/R-MTB strains, while using  with standard dose of Mfx or solely, and usage of  5,0% solution demonstrated minimal bactericidal effect.  In vitro usage of standard dose of Mfx with addition of 20 nm  2.5% AgNPs nanocomposite solution increased minimal inhibitory effect by 16.7% on Mfx/R-MTB strains (86.7%) compared to using only 20 nm  2.5% solution of AgNPs (70%). 

Conclusion:  The study of the effectiveness of the nanocomposite on pre-XDR MTB strains in vitro showed potential influence of AgNPs on overcoming resistance against Mfx.