RESTRICTION-FRAGMENT-LENGTH-POLYMORPHISM ANALYSIS OF DRUG-RESISTANT MYCOBACTERIUM-TUBERCULOSIS STRAINS ISOLATED IN BELGIUM

The recently identified insertion element IS6110 is present in most st rains of the Mycobacterium tuberculosis complex. Restriction fragment length polymorphism (RFLP) based on IS6110 generates strain specific f ingerprints and allows typing of M. tuberculosis strains. We present h ere the results of a RFLP study on 12 multi drug and 10 single drug re sistant, recent isolates of M. tuberculosis received from different cl inical microbiology laboratories in Belgian hospitals. All isolates or iginating from different patients yielded distinct RFLP patterns posse ssing 2 to 13 copies of IS6110. There was no correlation between the n umber or location of IS6110 copies and the drug resistance patterns. T hese results illustrate the existence of a broad polymorphism among Be lgian isolates. Though this preliminary study did not reveal an outbre ak or a micro-epidemic, we consider that the establishment of a DNA fi ngerprint bank in Belgium will be extremely helpful for tracing recent sources of infection, for the control of a possible spread of multidr ug resistant organisms, and for the surveillance of tuberculosis in ge neral.