Microbiological evaluation of clinically suspected cases of tubercular lymphadenopathy by cytology, culture, and smear microscopy – A hospital-based study from Northern India

Abstract

Introduction: Over the past few years, the incidence of extrapulmonary tuberculosis (EPTB), particularly of tubercular lymphadenitis (TBLN), is on the rise. TBLN, which contributes to 20–40% of EPTB cases, often poses a diagnostic and therapeutic challenge for clinicians more so in resource-constrained settings where laboratory confirmation is not available. In this study, we aimed to study if fine-needle aspiration cytology (FNAC) combined with Ziehl–Neelsen (ZN) staining and mycobacterial culture could improve the diagnostic accuracy in patients clinically suspected of TBLN. Materials and Methods: This cross-sectional study involved 120 patients (>12 years of age), clinically suspected of peripheral TBLN. Direct examination of the samples with ZN staining and culture on Lowenstein–Jensen (LJ) slants and Bactec MGIT 960 vials (MGIT 960 medium) was performed on previously collected fine-needle aspirates. Results: Out of total 120 patients included in study, 43.3% were males and 56.7% were females. Maximum numbers of cases were observed in age group 13–21 (56%). On ZN staining, 21.7% samples were found positive, whereas FNAC findings were suggestive of tuberculosis (TB) in 455 patients. Culture on LJ media showed 33.3% samples to be positive, whereas Bactec MGIT 960 system showed positivity of 35%. Out of 54 samples suggestive of TB on FNAC, only 30 (55.6%) were found positive on Bactec culture. Also out of 66 samples which were not suggestive of TB in FNAC, 12 (18.2%) were found positive in Bactec culture. Conclusion: Accurate diagnosis of TBLN requires a multifaceted approach involving microbiology, pathology, radiology, and clinical presentation of the disease. FNAC and ZN staining along with the culture can result in better diagnostic yield and will be helpful in reducing the burden of TB.

Keywords

• Acid-fast bacilli
• MGIT
• Mycobacterium tuberculosis
• tubercular lymphadenitis
• ZN staining