Cytopathological and Bacteriological Diagnostic Performance of GeneXpert in Clinically Suspected Tuberculous Lymphadenitis in a Tertiary Care Hospital, Bihar (India)

BACKGROUND
\nTuberculosis is a prehistoric disease and confirmation of its existence was seen in
\nthe Vedas. The oldest of them (Rigveda, 1500 BC) calls the infection yaksma. It
\nclaimed millions of lives in Europe and was called `The White Plague’. Robert Koch
\nhas written that tuberculosis killed one third of Europeans of middle age.
\nMETHODS
\nThis is a descriptive study. Tuberculous lymphadenitis isolates from sputum
\nsamples of clinically suspected cases of tuberculosis seen in Vardhman Institute of
\nMedical Sciences, Pawapuri, Nalanda, Bihar and Associated Hospital of Bihar
\nbetween March 2019 and March 2020 were included in the study. The study
\nprotocol was approved by the hospital ethics committee.
\nRESULTS
\nA total of 200 fine-needle aspirated specimens from lymph nodes were integrated
\nin the study. Out of 200 cases, 90 aspirates were reported as cytomorphology
\nsuggestive of tuberculous lymphadenitis. Compared to the reference standard,
\nXpert MTB/RIF correctly identified 88 out of 90 TB cases (sensitivity, 97.80%).
\nThe possible false-negative result had a prolonged transit interval of 9 days before
\nXpert MTB/ RIF testing, which may have affected the result. Xpert MTB/ RIF was
\npositive in two cases, with negative cytomorphology and culture (specificity,
\n95.65%). The cytomorphology from one of the false-positive results showed a
\nnecrotizing suppurative lymphadenitis, which is consistent with TB. However, no
\norganisms could be identified on microscopy or culture. The cytomorphology of
\nthe other false positive result showed an epithelial inclusion cyst, and the reason
\nfor this false-positive result remains unknown.
\nCONCLUSIONS
\nFNAB is a simple procedure which can be performed in an outpatient setting by
\nclinicians or nursing staff after a short training period (21, 22). It is ideal for use
\nin resource-limited settings, including more remote and rural areas (22). Specimen
\ncollection is simple and safe. With the use of a transport vial, virtually no sample
\npreparation is required and there is minimal risk of contamination. Furthermore,
\nthe transmission risk to the operator may also be reduced. Combining FNAB and
\nrapid genotypic diagnosis using automated systems should greatly improve access
\nto appropriate diagnosis and treatment for patients with tuberculous
\nlymphadenitis.