Lung infection caused by Blastoschizomyces capitatus without immunodeficiency: a case report and review of the literature

Background: Blastoschizomyces capitatus infection is a rare fungal infection; mainly occurring in immunodeficient patients, which can cause multiple organ involvement. At present, there is no clear designated treatment regimen. This case was a rare example of Blastoschizomyces capitatus lung infection in patient with normal immune function, which was effectively controlled by combined antifungal therapy.Case Description: We report a 67-year-old male smoker, who, after cleaning a small bungalow for a long period, without any protective measures, developed cough with expectoration, fever and dyspnea. Pre-admission anti-infective medication (amoxicillin and roxithromycin) had little effect, and the patient's condition worsened. He had a past history of pulmonary tuberculosis with pleurisy 6 years before. Chest computed tomography (CT) showed evidence of old tuberculosis in the right upper lobe and inflammation in both lower lobes. White blood cell count was 14.51x109/L, neutrophils was 13.39x109/L and C-reactive protein (CRP) was 170 mg/L. Broad-spectrum antibiotics piperacillin sodium 4.0 g and tazobactam sodium 0.5 g q8h were administered empirically for 5 days. Blastoschizomyces capitatus infection was confirmed by next generation of macro genome sequencing (NGS) of bronchoalveolar lavage fluid and mass spectrum analysis of sputum. He was then switched to voriconazole antifungal therapy combined with aerosol inhalation of amphotericin B. His temperature normalized, expectoration and dyspnea were relieved. Total white cell count fell to 8.10x109/L, neutrophils to 5.81x109/L, and CRP to 76.8 mg/L.Conclusions: This case demonstrates that Blastoschizomyces capitatus infection can occur in patients with normal immune function. Mass spectrometry and metagenomic NGS methods may have an advantage over traditional methods in identifying this fungal infection. In addition, the combination of voriconazole and nebulized amphotericin B can be employed as a novel regimen for treating Blastoschizomyces capitatus infection. For pulmonary infection with a history of environmental exposure, early pathogen identification and culture, and appropriate antibiotic treatment are key to optimizing outcome.