MULTIPLEX PCR ASSAY SPECIFIC FOR THE MULTIDRUG-RESISTANT STRAIN-W OF MYCOBACTERIUM-TUBERCULOSIS

In 1991, a multidrug-resistant strain of Mycobacterium tuberculosis wa s isolated from eight people with tuberculosis at a state correctional facility in New York. This strain, which is designated strain W (IS61 10 restriction fragment length polymorphism type 212072), was resistan t to isoniazid, rifampin, ethambutol, streptomycin, kanamycin, ethiona mide, and rifabutin. Since that outbreak, the W strain has been associ ated with outbreaks in five hospitals in the New York City area and is a continuing public health problem in the area. To be able to identif y this strain rapidly, we developed a multiplex PCR assay which target s a direct repeat of IS6110 with a 556-bp intervening sequence (NTF-1) . The amplification generates two amplicons from strain W, which indic ate the presence and orientation of the NTF-1 sequence between the dir ect repeat of IS6110, and a third amplicon, which serves as an interna l PCR control. The assay was evaluated with 193 isolates of M. tubercu losis, and all 48 strain W isolates among those 193 isolates were corr ectly identified.