DIAGNOSING NTM IN IMMUNOCOMPETENT CHRONIC LYMPHADENITIS: AN EMERGING ENITITY

Introduction: Cervical lymph node infection due to nontuberculous mycobacteria in a immunocompetent patients are emerging problem globally. It is presented as chronic enlargement of gland with pain and pus discharge sometimes. Traditionally diagnosis is done through clinical examination, lymph node aspirated samples pathological finding or ZN microscopy, which altogether indicate mycobacterial infection only, unable to differentiate MTB from NTM infection.Increasing incidence of LNTB cases not responding to antituberculous treatment prompted us to pinpoint the etiological agent by doing liquid culture of FNA samples in microbiology laboratory.

Materials and Methods: In this study 154 cases were recruited having chronic cervical lymph node swelling of suspicion of mycobacterial infection during January - December, 2014. Therein detailed history and thorough clinical examination of patients were reviewed. All patients were subjected for fine needle aspiration (FNA) using 10 ml syringe fitted with 21 G needle. The aspirated samples were subjected to smear microscopy byZiehlNeelsen (ZN) stain examination, May Grunwald - Giemsa stain and MGIT culture. Positive cultures were primarily identified by cord formation in ZN smear examination, detection of MPT-64 antigen by immuno-chromatographic test (Capilia test). 

Results: A total 154 lymph node samples were received and processed for culture during the study period. Out of total suspects 7/154 (4.5%) were identified as non-tuberculous mycobacterial lymphadenitis. Clinical examination showed that all the seven cases were presented with lymph node swelling and fever and previous ATT history. Other features seen were pain (2/7 28%), pus discharge (3/7 42%) and montoux positive (3/7 42%). The most common species identified was M. chelonae (3/7, 42%) followed by M. fortuitum (2/7, 28%), M. abscessus (1/7, 14%) and M.terricomplex (1/7, 14%). Four patients were managed surgically, one with surgical resection and medical treatment and 2 patients were lost tofollowup.

Conclusion: Definitive and detailed microbiological examination is vital for diagnosing the nontuberculous lymphadenitis. M.chelonae is an important etiological agent.NTMs are important definitive etiological agents in cervical lymph node swelling. Clinical and pathological findings help in suspecting the infection.