In vitro susceptibility testing of Mycobacterium tuberculosis strains to trifluoperazine

The presence of calmodulin-like protein (CAMLP) has been demonstrated in mycobacteria and it has been observed that there is a positive correlation between levels of CAMLP, phospholipids as well as lipids and growth. Thus the use of trifluoperazine, which is a calmodulin antagonist, would inhibit the growth of mycobacterial cells. The authors carried out in vitro susceptibility testing of Mycobacterium tuberculosis strains to trifluoperazine with their minimum inhibitory concentrations (MIC) determination. 70 strains of M. tuberculosis isolated from cases of pulmonary as well as extrapulmonary tuberculosis were included. The following antimycobacterial drugs: streptomycin, isonized, rifampicin, ethambutol were tested on Lowerstein and Jenson (LJ) slopes using the resistance ratio method and the proportion method for pyrazinamide testing. All strains and the control H37RV were cultured into Youmans and Karlson's liquid medium and MICS were determined for trifluoperazine. Trifluoperazine MICs ranged between 8-32 microg/ml for strains susceptible to routine antimycobacterial drugs while strains resistant to streptomycin and isoniazid had lower MIC values, between 8-16 microg/ml. As trifluoperazine is already in human use for psychotic disorders, its antitubercular activity could pave the way for human trials as an antitubercular drug.