Comparison of radiorespirometric budemeyer assay with ATP assay and mouse foot pad test in detecting viable Mycobacterium leprae from clinical samples

Purpose: This study compares the results of radiorespirometric Buddemeyer assay with adenosine triphosphate (ATP) assay and mouse foot pad (MFP) test to validate the sensitivity of Buddemeyer assay in detecting viable M. leprae in clinical samples.
Methods: Viability was assessed using all the three methods in 60 skin biopsy specimens, including 20 untreated lepromatous leprosy (BL-LL), 13 treated BL-LL, 12 untreated borderline tuberculoid to mid borderline (BT-BB) and 15 treated BT-BB cases.
Results: Of the 20 untreated BL-LL cases tested, positivity indicating the presence of viable M. leprae was detected in 85, 60 and 85% with Buddemeyer, ATP and MFP test, respectively. Among the 13 treated BL-LL cases, scores were 61, 54 and 0%; among the 12 untreated BT-BB cases, the scores were 58, 16 and 16% and among the 15 treated BT-BB cases, the scores were 46, 20, 0%, respectively.
Conclusion: The detection sensitivity (positive scores) with three tests were closely comparable in the two untreated groups of cases. On the other hand, in the two treated groups, a good proportion of cases scored positive in the in vitro tests but none in the MFP test. Among the two in vitro methods, the Buddemeyer assay emerged as a better test, in terms of sensitivity and specificity.

Keywords
adenosine triphosphate assay, M. leprae, mouse foot pad test, radiorespirometric Buddemeyer assay, viability