Effect on Mycobacterium tuberculosis Clinical Isolates Susceptibility Against First and Second-line Drugs Using MGIT 960

Background and Objective: With the expanding knowledge about efflux pumps contribution to the resistance mechanism of Mycobacterium tuberculosis has increased the attention to efflux inhibitors usage as adjuvants in tuberculosis therapy. Therefore, this study examined the effect and interaction between efflux inhibitor towards first (isoniazid, streptomycin, rifampicin, ethambutol) and second-line (kanamycin, ofloxacin, capreomycin, moxifloxacin) anti-tuberculosis drugs in M. tuberculosis susceptibility. Materials and Methods: Sixty-five M. tuberculosis isolates collected from sputum samples of tuberculosis patients in Makassar and exposed to anti-TB drugs at critical concentration in the presence or absence of verapamil (40 g mLG 1 ) using drug susceptibility test (DST) proportion method in Mycobacterium Growth Indicator Tube (MGIT) 960 system. Results: About 14 isolates (21.54%) were mono-resistant, 20 isolates were MDR-TB (30.67%), 20 isolates (30.67%) were Pre XDR-TB and 7 isolates (10.77%) were XDR-TB. There were 8 drugs that were tested but only 6 drugs showed a decrease of mean growth unit in STR, INH, RIF, CAP, OFX and MOXI after the addition of efflux pump inhibitor (synergy observed). The overall effect of verapamil towards all groups of drugs tested showed p-value of 0.001 (p<0.05). Conclusion: It was concluded that the addition of verapamil plays a significant role in restoring the susceptibility of M. tuberculosis isolates.