In a recent Indian study, a total of 3181 samples were

processed for isolation of tubercle bacilli; and 707 samples

were culture positive. The pattern of drug resistance is

shown in the following table:

Pattern of drug resistance for mycobacterium

tuberculosis

Drug Percent resistance

Isoniazid 30.41

Rifampin 58.55

Streptomycin 46.95

Ethambutol 3.67

D-Cycloserine 24.32

Kanamycin 14.42

Ethionamide 60.67

Amikacin 15.84

Ciprofloxacin 7.49

860 Concise Book of Medical Laboratory Technology: Methods and Interpretations

In India, it has been observed that private practitioners

use different drug regimens to treat tuberculosis and very

few regimens match with the standard (recommended by

WHO).

The problem of acquired drug resistance (ADR) is

truly man made. Poor administered tuberculosis control

program, inadequate dosages, monotherapy, insufficient

durations of treatment, irregularity in drug intake, frequent

defaults are some of the common reasons for emergence

of ADR. In addition, HIV is quickening the pace at which

Tuberculosis is spreading. Therefore, Tuberculosis is

becoming the leading killer disease of HIV-positive people.

Clinicians should ensure that Mycobacterium tuberculosis

susceptibility tests are carried out for patients:

¾ Who fail to respond after 3 months of treatment

¾ Who do not convert to having negative smears after

3 months of treatment; with regimens that include INH

and Rifampin, and 5 months for treatment without INH

and Rifampin

¾ Whose smears demonstrate increasing number of AFB

after an initial decrease

¾ Patients whose cultures do not become negative after

4–6 months

¾ Patients who relapse

TB susceptibility testing has three main goals:

¾ It provides data as to what drug should be used for

treatment

¾ Screens for drug resistance

¾ Measures incidence and prevalence of drug resistance

within the community.