Clinical efficacy and diagnostic value of metagenomic next-generation sequencing for pathogen detection in severe aplastic anemia patients with suspected infectious diseases

Abstract Introduction: Aplastic anemia (AA) is a rare and life-threatening hematologic disorder, with infections posing significant mortality risks. This study aimed to evaluate the diagnostic value and treatment impact of blood metagenomic next-generation sequencing (mNGS) in severely aplastic anemia (SAA) patients with suspected infections. Methods: A retrospective analysis was conducted on 24 adult patients diagnosed with SAA and treated at the Peking University Institute of Hematology, Peking University People's Hospital, between August 2023 and March 2025. All patients underwent blood mNGS testing. The patients were classified into infection (n=19) and non-infection (n=5) groups based on clinical evaluation. Additionally, 5 healthy individuals were recruited as controls for comparative analysis. Results: No significant differences were observed in age, gender, or prevalence of comorbidities among infection, non-infection, and control groups (P > 0.05). The most common clinical manifestation was cutaneous ecchymosis or hemorrhagic spots (66.67%), followed by fatigue (54.27%). Both patient groups exhibited significantly lower levels of white blood cells (WBC), red blood cells (RBC), platelets (PLT), and hemoglobin (Hb) compared to the control group (P < 0.05). Among the 37 blood samples collected from the 19 infected patients, mNGS demonstrated a significantly higher pathogen detection rate (78.38%) compared to blood culture (32.14%, P < 0.0001) and conventional microbiological tests (CMT, 42.34%, P = 0.0039), with significantly enhanced sensitivity for bacterial, viral, and polymicrobial infections (P < 0.05). Compared with blood culture, the proportion of cases with both positive blood culture and mNGS results in the infection group was 21.43%, and 17.86% of the cases detected the same pathogen. Compared with CMT, 32.43% of the cases detected the same pathogen. Microbiological profiling indicated a higher prevalence of Gram-negative bacteria, particularly Pseudomonas aeruginosa and Stenotrophomonas maltophilia. Enterococcus faecium was the most common Gram-positive bacteria. Aspergillus was the most prevalent fungus, with additional isolates including Candida albicans, Pneumocystis jirovecii, and Rhizopus delemar. Among the viral pathogens, herpesviruses, particularly Epstein-Barr virus (EBV) and herpes simplex virus type 1 (HSV-1), were most commonly identified. Regarding medication guidance, mNGS had a positive impact on 78.38% of the cases, had no impact on 21.62% of the cases, and had no negative impact. Analysis of the diagnosis and treatment of cases that underwent multiple mNGS tests found that mNGS can dynamically detect changes in the infection status of patients, timely guide the adjustment of medication dosage and types, and improve the prognosis of patients. Conclusions: mNGS provides critical diagnostic and therapeutic guidance for SAA patients. Continuous mNGS surveillance provides critical insights into infection dynamics and supports the optimization of clinical management strategies, thereby demonstrating significant clinical utility in this high-risk patient population. Key words:Severe aplastic anemia，Infections，mNGS