Isolation of Mycobacterium lepromatosis and Development of Molecular Diagnostic Assays to Distinguish Mycobacterium leprae and M. lepromatosis.
BACKGROUND
Mycobacterium leprae was thought to be the exclusive causative agent of leprosy until Mycobacterium lepromatosis was identified in a rare form of leprosy known as diffuse lepromatous leprosy (DLL).


METHODS
We isolated M. lepromatosis from a patient with DLL and propagated it in athymic nude mouse footpads. Genomic analysis of this strain (NHDP-385) identified a unique repetitive element, RLPM, on which a specific real-time quantitative polymerase chain reaction assay was developed. The RLPM assay, and a previously developed RLEP quantitative polymerase chain reaction assay for M. leprae, were validated as clinical diagnostic assays according to Clinical Laboratory Improvement Amendments guidelines. We tested DNA from archived histological sections, patient specimens from the United States, Philippines, and Mexico, and US wild armadillos.


RESULTS
The limit of detection for the RLEP and RLPM assays is 30 M. leprae per specimen (0.76 bacilli per reaction; coefficient of variation, 0.65%-2.44%) and 122 M. lepromatosis per specimen (3.05 bacilli per reaction; 0.84%-2.9%), respectively. In histological sections (n = 10), 1 lepromatous leprosy (LL), 1 DLL, and 3 Lucio reactions contained M. lepromatosis; 2 LL and 2 Lucio reactions contained M. leprae; and 1 LL reaction contained both species. M. lepromatosis was detected in 3 of 218 US biopsy specimens (1.38%). All Philippines specimens (n = 180) were M. lepromatosis negative and M. leprae positive. Conversely, 15 of 47 Mexican specimens (31.91%) were positive for M. lepromatosis, 19 of 47 (40.43%) were positive for M. leprae, and 2 of 47 (4.26%) contained both organisms. All armadillos were M. lepromatosis negative.


CONCLUSIONS
The RLPM and RLEP assays will aid healthcare providers in the clinical diagnosis and surveillance of leprosy.
['Sharma|Rahul|R|', 'Singh|Pushpendra|P|', 'McCoy|Rajiv C|RC|', 'Lenz|Shannon M|SM|', 'Donovan|Kelly|K|', 'Ochoa|Maria T|MT|', 'Estrada-Garcia|Iris|I|', 'Silva-Miranda|Mayra|M|', 'Jurado-Santa Cruz|Fermin|F|', 'Balagon|Marivic F|MF|', 'Stryjewska|Barbara|B|', 'Scollard|David M|DM|', 'Pena|Maria T|MT|', 'Lahiri|Ramanuj|R|', 'Williams|Diana L|DL|', 'Truman|Richard W|RW|', 'Adams|Linda B|LB|']
D000818:Animals D006801:Humans D008800:Mexico D051379:Mice D009161:Mycobacterium D009166:Mycobacterium leprae D057089:Pathology, Molecular
Mycobacterium lepromatosis Mycobacterium leprae leprosy diagnostic assay real-time PCR