048. Common errors in the diagnosis of pulmonary tuberculosis: case report

Background: Pulmonary tuberculosis is characterized by a subacute clinical course and non-specific clinical manifestations and therefore, not uncommonly its diagnosis can be delayed.

Case report: Cause of admission: A 36-year-old previous healthy young woman, current smoker, was admitted due to productive cough and episodes of night rigor, commencing 20 days before. Imaging studies (plain chest radiograph and thoracic CT scan) revealed the presence of tree-in-bud lesions and large thick-walled cavities in the upper lung fields bilaterally. Present illness: She complained of a chronic productive cough in the previous year treated with repeated courses of clarithromycin. A chest radiograph two years before (obtained at the request of her health security agency) had revealed multiple nodular lesions in the right upper lung field, however no further investigation was performed. Diagnostic investigations: Tuberculin skin sensitivity test: 0 mm; interferon gamma assay: 0.42 IU/L (weakly positive), HIV test: negative, peripheral blood CD4/CD8 ratio: 0.76. Sputum smear and culture were positive for an acid fast bacillus, which was identified as Mycobacterium tuberculosis (transcription mediated amplification, AMTD, Gene Probe). It was sensitive to all primary drugs. Disease course and management: She was started on a 4-drug regimen consisting of INH, RIF, PZA and EMB. Cough and constitutional symptoms improved within the first two weeks. Sputum smear became negative by the 1^st month of treatment and cultures were sterilized by the 2^nd month. A new chest radiograph at the 4^th month revealed an almost complete obliteration of the cavities.

Conclusions: The delay in the diagnosis of tuberculosis in this particular patient is due to failure to appraise (I) the duration of symptoms (II) the early presence of radiological findings and (III) the poor response to conventional antimicrobial treatment.

Keywords: Tuberculosis; bronchoscopy; spirometry