Abstract
BACKGROUND: Tuberculosis (TB) remains a global health concern despite decreasing incidence. Delayed TB diagnosis can exacerbate patient outcomes and lead to broader public health issues such as mass infections. Differentiation between TB and bacterial pneumonia is often complicated by variable clinical and radiological manifestations of TB, leading to diagnostic delays. CASE SUMMARY: An 89-year-old, Japanese male patient with a history of diabetes mellitus, hypertension, and hypothyroidism presented with right-sided chest pain. Based on the elevated inflammatory response, right pleural effusion, and infiltrating shadow in the lung field, the diagnosis of right pleurisy was made and the antibiotic, ampicillin/sulbactam, was administered. The patient's condition, inflammatory reaction, and right pleural effusion temporarily improved. However, persistent low-grade fever and malaise prompted further evaluation, revealing repeated right pleural effusion and inflammatory response. A right thoracentesis was performed; the patient was diagnosed with tuberculous pleurisy as a result of exudative effusion with lymphocyte predominance, elevated adenosine deaminase levels, and positive Mycobacterium TB polymerase chain reaction test. Anti-TB treatment, including isoniazid, rifampicin, and ethambutol was initiated, leading to significant clinical improvement. The patient successfully completed a 12-month course of TB therapy without recurrence or deterioration. CONCLUSION: There are cases of TB wherein temporary improvement apparently could be shown through treatment with antimicrobial agents other than anti-TB drugs, necessitating careful evaluation in atypical cases of bacterial pneumonia.