SIMULTANEOUS DETECTION AND STRAIN DIFFERENTIATION OF MYCOBACTERIUM-TUBERCULOSIS FOR DIAGNOSIS AND EPIDEMIOLOGY

Widespread use of DNA restriction fragment length polymorphism (RFLP) to differentiate strains of Mycobacterium tuberculosis to monitor the transmission of tuberculosis has been hampered by the need to culture this slow-growing organism and by the level of technical sophisticatio n needed for RFLP typing. We have developed a simple method which allo ws simultaneous detection and typing of M. tuberculosis in clinical sp ecimens and reduces the time between suspicion of the disease and typi ng from 1 or several months to 1 or 2 days. The method is based on pol ymorphism of the chromosomal DR locus, which contains a variable numbe r of short direct repeats interspersed with nonrepetitive spacers, The method is referred to as spacer oligotyping or ''spoligotyping'' beca use it is based on strain-dependent hybridization patterns of in vitro -amplified DNA with multiple spacer oligonucleotides, Most of the clin ical isolates tested showed unique hybridization patterns, whereas out break strains shared the same spoligotype. The types obtained from dir ect examination of clinical samples were identical to those obtained b y using DNA from cultured M. tuberculosis. This novel preliminary stud y shows that the novel method may be a useful tool for rapid disclosur e of linked outbreak cases in a community, in hospitals, or in other i nstitutions and for monitoring of transmission of multidrug-resistant M. tuberculosis. Unexpectedly, spoligotyping was found to differentiat e M. bovis from M. tuberculosis, a distinction which is often difficul t to make by traditional methods.