Detection of Mycobacterium leprae in ocular tissues by histopathology and real-time polymerase chain reaction.
OBJECTIVE
To report detection of leprosy in ocular tissue by histopathology and its confirmation by genetic analysis.


METHODS
Excised tissue from a clinically-suspected ocular leprosy patient was processed and analyzed histopathologically. The DNA from the paraffin-embedded tissue was extracted, an 85 A-C intergenic region of Mycobacterium leprae was amplified using specific primers and analyzed by conventional as well as real-time polymerase chain reaction (RT-PCR).


RESULTS
With periodic acid-Schiff-hematoxylin (PAS-H) staining the specimen showed presence of a thin fibrinous layer of inflammatory cells. The majority of the tissue was fibrovascular with extensive infiltration by histiocytes having reticulated cytoplasm. Modified PAS-H and acid-fast staining (AFS) showed the presence of several acid-fast organisms within the cytoplasm of histiocytes and mast cells. Conventional PCR showed a 250-bp DNA from excised conjunctival tissue, which was in agreement with the positive controls for M. leprae. Through RT-PCR, it was calculated that the suspected tissue had 44.68 pg of M. leprae DNA, which is 8937.06 genome copies of M. leprae.


CONCLUSIONS
Presence of inflammatory cells and AFS bacilli in tissue presented a typical picture of leprosy. M. leprae DNA can be detected using RT-PCR in ocular tissues when acid-fast bacteria are seen in histopathological sections. And when the diagnosis of leprosy is inconclusive and acid-fast bacteria are seen, RT-PCR for M. leprae DNA could be used as a rapid confirmatory test to identify the presence of M. leprae and, therefore, the diagnosis of leprosy.
Shamsi
Farrukh A
FA
Research Department, King Khaled Eye Specialist Hospital, Riyadh, Saudi Arabia. dr_farrukhshamsi@yahoo.com
Chaudhry
Imtiaz A
IA
Moraes
Milton O
MO
Martinez
Alejandra N
AN
Riley
Fenwick C
FC
D000328:Adult; D003229:Conjunctival Diseases / Q000382:microbiology / Q000473:pathology*; D004269:DNA, Bacterial / Q000032:analysis*; D015818:Eye Infections, Bacterial / Q000382:microbiology / Q000473:pathology*; D005260:Female; D006801:Humans; D007918:Leprosy / Q000382:microbiology / Q000473:pathology*; D009166:Mycobacterium leprae / Q000235:genetics / Q000302:isolation & purification*; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods*
D004269:DNA, Bacterial