Restriction fragment length polymorphism typing of clinical isolates of Mycobacterium tuberculosis from patients with pulmonary tuberculosis in Madras, India, by use of direct-repeat probe.
Sahadevan, R.; Sujatha Narayanan; Paramasivan, C.N.;
Prabhakar, R.; Narayanan, P.R.
Journal of Clinical Microbiology; 1995; 33; 3037-3039.
Large numbers of Mycobacterium tuberculosis isolates that were obtained from patients' sputa on diagnosis and during follow-up after short-course chemotherapy in Madras, India, have either no copy or only a single copy of IS6110. This poses a limitation for DNA fingerprinting with an IS6110-based probe to determine the frequency of exogenous reinfection versus that of endogenous reactivation. In the present study, we overcame this limitation by using an alternate probe, the direct-repeat element. Comparison of pre- and postreatment isolates by direct-repeat restriction fragment length polymorphism analysis indicated a high degree of endogenous reactivation among patients who have relapses after the successful completion of chemotherapy.
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