RESTRICTION-FRAGMENT-LENGTH-POLYMORPHISM STUDY OF MYCOBACTERIUM-TUBERCULOSIS IN THAILAND USING IS6110 AS PROBE

SETTING: Three referral hospitals in central Thailand. OBJECTIVE: To d etermine the population structure of Mycobacterium tuberculosis isolat ed from the referral hospitals. DESIGN: Study of 211 isolates of the b acteria received from the hospitals in central Thailand by Southern hy bridization, with IS6110 probe and other probes when indicated. RESULT S: In 43 isolates only one copy of IS6110 was observed. These could be further differentiated by DR- and PGRS-specific probes. Two large gro ups of isolates with similar hybridization patterns were identified. T he Beijing family, comprising 80 isolates, was previously reported to be commonly found in China, Mongolia, Thailand and Korea. The Nonthabu ri group, comprising 29 isolates, were local strains. The age, sex and HIV status of the patients did not significantly correlate with the c hance of being infected by isolates of any particular hybridization pa ttern. However, clustered isolates were found more commonly among the members of both the Beijing family and the Nonthaburi group. CONCLUSIO N : Southern hybridization with IS6110 was found to be useful in study ing the epidemiology of tuberculosis in Thailand. The existence of the Beijing family was confirmed. The unusually wide spread of the Beijin g family in several countries in Asia merits further investigation.