DETECTION OF MYCOBACTERIUM-LEPRAE INFECTION BY PCR

PCR amplification of the 531-bp fragment of the Mycobacterium leprae p ra gene in fresh biopsy and slit skin smear samples was evaluated for its usefulness in the detection of leprosy bacilli in patients in Thai land. In multibacillary patients, 87.1% (27 of 31) of biopsy specimens and 41.9% (13 of 31) of slit skin smear specimens were positive by PC R, whereas in paucibacillary patients, 36.4% (8 of 22) of biopsy speci mens and 18.2% (4 of 22) of slit skin smear specimens yielded detectab le PCR amplification. Compared with other diagnostic procedures, PCR s howed a clear advantage over both microscopic examination of slit skin smears and serologic detection of anti-phenolic glycolipid 1 antibody , especially in paucibacillary patients when bacterial indexes were 0 and seropositivity was only 6.25%, PCR was also evaluated for its pote ntial to help monitor bacterial clearance in some of these patients du ring chemotherapeutic treatment, The PCR results on slit skin smear sa mples at 1, 3, and 6 months of chemotherapy showed that the number of PCR-positive cases of bath multibacillary and paucibacillary types dec reased sequentially, The results of this study are encouraging, Howeve r, investigation of a larger number of clinical specimens with an impr ovement in PCR methods, especially on slit skin smears, needs to be do ne before PCR can be established as a diagnostic procedure for leprosy patients and subclinical cases or as a tool for drug assessment.