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Mycobacterium tuberculosis does not show evidence of molecular DNA in human cadaveric ocular tissues in an endemic setting
Author(s) -
Chauhan Harish,
Bansal Reema,
Kumar Aman,
Sharma Surya P.,
Gude Geethanjali,
Nahar Uma,
Singh Ramandeep,
Jain Arun K.,
Gupta Vishali
Publication year - 2019
Publication title -
clinical and experimental ophthalmology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.3
H-Index - 74
eISSN - 1442-9071
pISSN - 1442-6404
DOI - 10.1111/ceo.13654
Subject(s) - medicine , pathology , mycobacterium tuberculosis , tuberculosis , polymerase chain reaction , histopathology , choroid , tropism , rifampicin , iris (biosensor) , virology , biology , retina , gene , biochemistry , virus , neuroscience , computer security , computer science , biometrics
Background Mycobacterium tuberculosis (MTB) in latent infection has been demonstrated in pulmonary/extra‐pulmonary locations (lung, spleen, liver, kidney, adipose tissue) in autopsy studies, but its presence in ocular tissues in the latent state is not known. Methods We conducted molecular and histopathological study of 100 cadaver eyes (50 humans) who died from causes other than tuberculosis (TB) (and were potential candidates for corneal transplantation) to detect MTB in ocular tissues in an endemic setting. After removal of the corneal button, an 8 to 10 mm block of tissue (choroid, retina and part of the vitreous) was excised from the remaining globe for DNA isolation. Gel‐based IS6110 and devR3 polymerase chain reaction (PCR) assays were done, followed by real‐time PCR using beta actin gene as an internal control. Sixteen randomly selected DNA samples were double checked using a commercial kit for MTB and non‐tuberculous mycobacteria (NTM) DNA. The remaining larger part of the globe was subjected to histopathology. Results The mean age was 65.14 ± 18 years. All 100 samples were negative for both IS6110 and devR, and all 16 samples were negative with NTM MTB commercial kit. All samples were negative with Ziehl‐Neelsen stain for acid fast bacilli and none showed any inflammation or granulomatous pathology. Conclusions MTB could not be detected in human ocular tissues in latent state in India, a TB‐endemic country. This may suggest the inability of MTB to seed ocular tissues in the latent state, unlike other organs which serve as reservoirs for the bacilli in the absence of manifest disease.