reactivation of latent tuberculosis ( tb ) is a serious hindrance to continuation of therapy . we present here a case of pleural tb in a patient on infliximab for ankylosing spondylitis . a 36-year - old male presented to our hospital in 2006 with low back ache inflammatory type with symmetric joint pains involving large joints such as shoulder joints , hip joints , knee joints , and small joints such as metacarpophalangeal joints , elbow joints , and metatarsophalangeal joints . there was associated early morning stiffness for over an hour . on examination , synovitis was present in peripheral joints with restriction of movement in all joints . modified schober 's test was positive , and the chest expansion ( <3 cm ) was restricted . on evaluation , he had anemia and elevated erythrocyte sedimentation rate ( esr ) ( 46 mm / h ) and c - reactive protein ( crp ) ( 18 mg / l ) . imaging revealed kyphoscoliosis of thoracic spine , syndesmophytes at multiple levels giving the appearance of bamboo spine [ figure 1 ] . diffuse ossification of interspinous and paraspinal ligaments with fusion of thoracic and lower cervical vertebra was present . radiograph showing bamboo spine in view of hla - b27 , more than 2 spa features and typical radiological features , ankylosing spondylitis was considered . he was started on nonsteroidal anti - inflammatory drugs ( nsaids ) and dose escalated for symptomatic relief . in view of persisting symptoms and elevated esr and crp in spite of optimal nsaids , following three doses of infliximab and 10 months after initiation of therapy , patient came with complaints of fever and cough for 1 week . on examination , breath sounds were reduced over the right side , and there was dullness on percussion . diagnostic thoracocentesis showed lymphocytic ( total leukocyte count - 4800 cells / cumm , lymphocytes - 90% ) exudative type of effusion with high adenosine deaminase ( ada ) ( 114 iu / l ) . according to light 's criteria ( effusion protein - 6 g / dl , serum protein - 3.37 g / dl , effusion lactate dehydrogenase ( ldh ) - 575 ankylosing spondylitis is a chronic , systemic , inflammatory disease that affects primarily the sacroiliac joints and spine . it is a spondyloarthropathy with a prevalence of 0.1%0.4% globally . data from india are sparse . its more commonly seen among males under 30 years of age . diagnosis is made after thorough clinical examination and radiography . infliximab is one such biologic which acts by inhibiting a pro - inflammatory cytokine tnf- and reducing inflammation . target - related adverse effects with tnf inhibitors are infections , opportunistic infections , malignancies , demyelinating conditions , hematologic abnormalities , congestive heart failure , autoantibodies ( antinuclear antibody and anti - double - stranded dna ) , hepatotoxicity , dermatologic reactions , and lupus - like syndromes , whereas the agent - related adverse effects are administration reactions and immunogenicity . tnf- is a cytokine that plays an important role in the mediation of inflammation and immune regulation . they are required for inflammatory response against intracellular organisms . in experimental models , fungal and bacterial infections pneumocystis carinii and histoplasma capsulatum are some of the fungal pathogens , whereas the bacterial agents are listeria monocytogene , mycobacterium tuberculosis , and mycobacterium avium . upper and lower respiratory tract infections are the most commonly seen ones . there was also an increased risk of serious infections compared with controls ( 3.6% vs. 1.7% ) . registries of rheumatoid arthritis patients have shown that the relative risk for infection ( 3.34.1 ) as well as serious infection ( 2.72.8 ) was significantly higher among patients receiving tnf inhibitors . to conclude , severity of disease , use of other medications such as corticosteroids , and the presence of comorbidities also contribute to infections in addition to tnf inhibitors alone . opportunistic infections following tnf inhibitor therapy include disseminated m. tuberculosis . in a study of seventy cases of tb following infliximab therapy , thirty were pulmonary tb and of forty were extrapulmonary disease , only two were cases of pleural tb . around a quarter of the cases were disseminated disease . the majority of cases of tb were observed within a median period of 12 weeks after initiation of therapy and is likely due to reactivation of latent tb . a study by grover et al . in india has shown a high incidence of tb ( 21% ) following biologic therapy . it was also seen that among those who received low doses of infliximab ( 3 mg / kg body weight ) did not develop tb . another study by malaviya et al . has found a lower incidence ( 9.4% ) of tb among those on tnf inhibitors . the rate of development of active tb among rheumatoid arthritis patients on anti - tnf therapy has dropped by 83% with the help of screening . suppressing the action of tnf- can help in relieving the symptoms of ankylosing spondylitis by reducing the inflammatory process , but at the same time , it weakens immune response to microbes such as tubercle bacilli . hence , meticulous screening and close monitoring of patients on infliximab for any symptoms and signs of tb are important as there is a risk even though the screening tests have come out be negative .
we present a case of pleural tuberculosis ( tb ) in a patient on infliximab for ankylosing spondylitis . 
 a 36-year - old male presented to our hospital with low back ache of inflammatory type along with multiple symmetric inflammatory type of joint pain . 
 further clinical examination , laboratory and radiological investigations were suggestive of ankylosing spondylitis . 
 he was initially treated with nonsteroidal anti - inflammatory drugs but citing poor response it was decided to initiate biologic therapy using infliximab ( antitumor necrosis factor - alpha ) . 
 mantoux test and chest radiograph were done before the therapy to rule out tb . following three doses of infliximab , 
 patient came with complaints of fever and cough for 1 week . on investigation 
 , it was found to be a case of pulmonary tb . 
 this shows the importance of close monitoring of patient for tb among patients on infliximab even though the screening test has come out to be negative .