An 8 days old male neonate was born to an Asian mother through vaginal delivery at 37 weeks of gestation, weighed 2,380 g, and had APGAR scores of 9 and 10 at 1 and 5 min, respectively. He was admitted to our hospital with a 2 days history of fever of up to 39 C but did not have respiratory or gastrointestinal symptoms. The infant's family denied any medical history and TB contact. His physical examination at admission documented smooth respiration, clear breathing sound, and no hepatosplenomegaly. The complete blood count indicated a total white blood cell count of 17,500/muL with 69% neutrophils, 20% lymphocytes, 9% monocytes, and 2% eosinophils. The C-reactive protein level was 7.3 mg/dL. The findings of the cerebrospinal fluid (CSF) analysis were normal. Bacterial cultures of the blood, urine, and CSF were negative. Intravenous antibiotics, namely cefotaxime and ampicillin, were administered after admission on the basis of suspicion of neonatal fever. Despite the administration of the antimicrobial combination therapy, the fever persisted and the neonate developed abdominal distension when he was 12 days old. Abdominal radiography exhibited nonspecific dilated bowel loops. Because no improvement in the condition of the patient was observed after changing antibiotics, infection caused by some virus and other atypical pathogen, including Mycobacterium tuberculosis, was considered. Tests for herpes simplex virus, Epstein-Barr virus, cytomegalovirus, hepatitis B virus, rubella, Chlamydia trachomatis, and Toxoplasma gondii were all negative. The repeat C-reactive protein level was elevated to 14.4 mg/dL. Coagulopathy with 323.7 mug/mL of abnormal fibrin degradation product and more than 20 mg/L of D-dimer were also noted. Antibiotics were switched to vancomycin and ceftazidime empirically. Chest radiography displayed only increased right lung field infiltration when the infant was 12 days old (Figure 1A), and chest computed tomography (CT) imaging exhibited a large amount of right pleural effusion with mild inflammatory changes in the right lower lobe when the infant was 15 days old (Figure 1B). Pleural effusion drainage was suggested but refused by his parents at that time. Gastric lavages for acid-fast staining and culture were examined when the infant was 20 days old after his parents agreed to further testing, and one of the three acid-fast stains of gastric lavages yielded few acid-fast bacilli. Repeat chest and abdomen CT imaging performed when the infant was 24 days old indicated patchy consolidation in the right upper lung, multiple new nodules in both the lungs, moderate pleural effusion, and multiple low-density nodules in the spleen and hepatic hilar region without hepatomegaly (Figures 1C,D). Subsequently, pigtail catheter insertion for pleural effusion drainage was performed. The findings of pleural fluid analysis indicated a total white blood cell count of 10,800/muL with 6% neutrophils, 57% lymphocytes, and 37% mesothelial cells; a total protein level of 4.6 g/dL, a lactic dehydrogenase level of 250 IU/L, and a glucose level of 164 mg/dL. TB infection was strongly suspected. The neonate was administered isoniazid (15 mg/kg/day), rifampicin (15 mg/kg/day), and pyrazinamide (20 mg/kg/day) when he was 24 days old. After initiating anti-TB treatment, the neonate's symptoms and signs subsided gradually. Finally, both gastric lavage and pleural effusion cultures showed M. tuberculosis complex.