A STUDY OF THE PH PHAGE SUSCEPTIBILITY TO M. TUBERCULOSIS ISOLATED FROM TUBERCULOSIS PATIENTS

Abstract

The PH phage specifically lyses M. tuberculosis, which had been maintained as the standard strain in our laboratory. Lytic activity of this phage against M. tuberculosis isolated from tuber culous patients was, however, somewhat different from that of our standard strain, namely, the phage susceptibility of patient's strains was lower than that of the standard strain. Strains of M. tuberculosis isolated from patients were slow growing rough colonies, cord forming acid-fast bacilli, absence of pigment formation, niacin biosynthetic and susceptible to INH, PAS and SM. Of the total 200 strains isolated from 106 patients, 25 strains (12.5%) obtained from 11 patients, of whom 8 had no clinical signs or previous history of tuberculosis, were susceptible to the PH phage when tested by means of spotting method. These phage susceptible mycobacteria were all sensitive to anti-tuberculous drugs; INH, PAS, SM and others. After the bacteriological confirmation of diagnosis, patients were treated usually by the triple conbination of INH, PAS and SM, and in some cases by rifampicin, ethambutol or kanamycin. Acid-fast bacilli converted to negative soon after the introduction of treatment. The phage susceptibility of strains isolated from the same patient at different times was always similar. In contrast, the drug resistant bacilli isolated from 11 patients with a long term history of pulmonary tuberculosis were all resistant to the phage. It has been said that no relationship exists between phage susceptibility and the drug resistance, however, the results of our present investigation suggest that there may be some relationship between drug resistance and the PH phage susceptibility.