Introduction of an in-house PCR for routine identification of M. tuberculosis in a low-income country.

ABSTRACT

SETTING: National Tuberculosis (TB) Treatment Centre, Makerere University Medical School and Joint Clinical Research Centre, Kampala, Uganda. OBJECTIVE: To evaluate the introduction of a polymerase chain reaction (PCR) based assay for identification of the Mycobacterium tuberculosis complex (MTC) into routine practice. DESIGN: Routine diagnostic specimens were processed and inoculated into Bactec 12B vials and monitored daily. At a growth index (GI) > or =10, 0.5 ml of the 12B broth was removed and assayed with PCR. The same 12B vial was analyzed using the Bactec NAP method at GI > or =500. Vials at various levels of GI were included. Recurrent cost and time required to perform PCR and NAP were compared. RESULTS: Initially, 71 specimens were analyzed; of these, 68 were NAP-positive while 69 were PCR-positive for MTC. PCR resulted in a 75% reduction in cost for a single test compared with Bactec NAP. PCR has been successfully incorporated into routine practice, and 432 samples have been analyzed. In addition, isolates from solid media were also well identified by PCR. With PCR, more samples can be analyzed at a time, it is faster and is less labor intensive. CONCLUSION: PCR is a reliable and cheaper alternative for the identification of MTC.