A Case of Hypoxemic Primary Cytomegalovirus Disease Shortly After Recovery From Coronavirus Disease in a Young Immunocompetent Man

Cytomegalovirus (CMV) reactivation has been identified as a significant predictor of death in patients hospitalized with coronavirus disease (COVID-19). However, reports of concurrent or subsequent primary CMV disease in young immunocompetent patients with COVID-19 are rare. We present a rare case of primary CMV disease manifesting as pneumonia and acute respiratory failure in a young immunocompetent man, which developed shortly after recovery from moderate COVID-19. A 19-year-old immunocompetent man was admitted to our hospital with a diagnosis of COVID-19 pneumonia on the 10^th day of COVID-19 onset. His symptoms improved following administration of intravenous dexamethasone, oral prednisolone, and oral azithromycin hydrate and levofloxacin hydrate. He was discharged on the 16^th day of COVID-19 onset. However, he developed a cough and fever 5 days after discharge, and he was readmitted to our hospital 8 days after discharge. Serum levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), C-reactive protein (CRP), and lactate dehydrogenase (LDH) were elevated compared to those during the first admission. Computed tomography revealed new ground-glass attenuations and the improvement in the aforementioned COVID-19 pneumonia. Next day, his percutaneous arterial oxygen saturation levels dropped to 89% breathing room air. Serum antibodies against CMV: immunoglobulin M (CMV IgM) and immunoglobulin G (CMV IgG), which were negative on the day of the first admission, became positive (CMV IgM titer, 5.82 [sample relative light units/cutoff] and CMV IgG titer, 58.6 [arbitrary units/mL]) on the 3^rd day of the second admission. The patient was diagnosed with primary CMV disease based on positive test results of the CMV antigenemia and deoxyribonucleic acid of CMV. The patient's symptoms, hypoxemia, and the new ground-glass attenuations improved following intravenous ganciclovir administration, without using corticosteroids. The clinical course in the present case suggests that CMV could have been the dominant causative pathogen for the new pneumonic shadows observed on the second admission. In cases where a second fever occurs shortly after recovery from COVID-19, clinicians should not assume prolonged COVID-19, and primary CMV disease should be considered as a differential diagnosis, even in young immunocompetent patients.