A 32-year-old woman, with history of BCG vaccination at the age of one, was hospitalized on 29 March 2020 with a 3-week-long high fever and muscle pain. The patient had a positive epidemiological link with travel to Milan, an area in Italy severely hit by COVID-19, and was treated with amoxicillin/clavulanic acid 1000 mg/BID and paracetamol 1000 mg/day.
On day one of hospitalization, the first nasopharyngeal swab RNA test for SARS-CoV2 genes resulted undetermined, while two subsequent tests were negative on day two and day three, respectively. High-resolution chest computer tomography (HRCT) revealed parenchymal consolidation of 54 x 25 mm, with associated air bronchogram, at the apical segment of the right upper lobe (RUL) (Fig. 1). Other consolidation areas with the same feature were located in the posterior segment of the same lobe in the parascissural site, in the middle lobe in the paramediastinal site, and contralaterally to the anterior segment of the left upper lobe (LUL) in the subpleural area. Large right pleural effusion leading to atelectasis of the right lower lobe (RLL) was also detected.
Blood tests revealed lymphopenia (900/mm3 and 15.6% of leukocyte formula) and increase in high sensitive C-reactive protein (hsCRP 18.08 mg/dL) and procalcitonin (PCT 0.43 ng/mL), fibrinogen, (882 mg/dL) and d-dimer (622 ng/mL). Antibiotic therapy was started with clarithromycin 500 mg/BID together with piperacillin/tazobactam 4.5 g/TID.
On day four, a new nasopharyngeal swab RNA test for SARS-CoV-2 genes resulted positive, while both IgG and IgM antibodies assays were negative. The patient was transferred to a dedicated COVID-19 unit, where hydroxychloroquine and antiviral therapy with lopinavir/ritonavir were initiated. A first measurement of QuantiFERON  gave an indeterminate result with the indication to repeat the exam because of insufficient production of gamma interferon upon stimulation with mitogen. HIV test was negative. QuantiFERON  and HIV tests were performed in the suspicion of tuberculous disease: therefore, both the location of the lesion and the patient's nationality had made way for a possible tuberculous infection obviously facilitated by a state of immunodeficiency.
On day seven, linezolid 500 mg/BID was introduced by replacing the previous antibiotic therapies due to the lack of clinical improvement. Thoracentesis was performed with the removal of 1 L of citrine yellow liquid. The chemical-physical and cytological analyses of the pleural fluid were consistent with exudative effusion, while culture tests for common germs and real-time polymerase chain reaction assay (RT-PCR) of Bacillus of Koch (KB) were both negative. Due to rapid relapse of large pleural effusion, pleural drainage with pigtail catheter was inserted. A second assay for the QuantiFERON  gave an indeterminate result. Due to the uncertain interpretation of chest CT images despite the reduction of pleural effusion, a lung CT biopsy procedure was performed with histological examination showing multiple areas of caseous necrosis delimited by a fibrous wall and giant multinucleated cells suggestive for tuberculosis infection. RT-PCR performed on histological samples resulted positive for KB.
Between day nine and day twelve, the patient repeated three nasopharyngeal swab RNA tests for SARS-CoV-2 genes which were negative, while clinical conditions improved. The antiviral therapy was first stopped followed by the hydroxychloroquine treatment. After discharge, the patient observed a 14-day quarantine period, and due to positive tests for tuberculosis, a combined therapy with isoniazid, rifampicin, pyrazinamide, and ethambutol was introduced. No oxygen therapy was required during hospitalization.