Coinfection of Cedecea lapagei and Aspergillus sydowii detected in bronchoalveolar lavage fluid of a patient with pulmonary infection using metagenomic next-generation sequencing: A case report

Background: Cedecea lapagei (C. lapagei), as a potential human pathogen, has been reported in limited cases of human infections in medical literature. However, the increasing frequency of isolating Cedecea lapagei from clinical specimens underscores its growing clinical significance that should not be underestimated. Aspergillus sydowii (A. sydowii), commonly isolated from various environments, serves as a pathogen of human cryptic aspergillosis. Clinical pathological changes caused by A. sydowii are not obvious, posing a significant challenge in clinical diagnosis. Consequently, metagenomic next-generation sequencing (mNGS) are required for precise differentiation and identification of pathogens. Case description: Here we present a case demonstrating successful treatment outcome in a patient with pulmonary infection caused by coinfection of C. lapagei and A. sydowii, as identified through metagenomic next-generation sequencing. The patient, a 50-year-old male, presented with worsening cough, sputum production, and hemoptysis. Metagenomic next-generation sequencing (mNGS) analysis of the bronchoalveolar lavage fluid (BALF) revealed the presence of both C. lapagei and A. sydowii. Subsequently, C. lapagei was also detected by culture in the same BALF sample, however while clinical fungal cultures and (1-3)-beta-D glucan testing yielded negative results. Based on these findings along with imaging features and clinical symptoms of the patient, the final diagnosis was determined to be a co-infection of C. lapagei and A. sydowii. Conclusion: The clinical manifestations of human infections caused by C. lapagei are not specific; patients with cryptic aspergillosis may have been previously overlooked due to improper specimen selection or negative routine tests. Therefore, precise identification of pathogens is crucial. This case report highlights the value of mNGS in detecting C. lapagei and A. sydowii in BALF, enabling timely diagnosis with coinfections.