Abstract: Objective To evaluate the application value of metagenomic next generation sequencing (mNGS) in AIDS suspected central nervous system (CNS) infection, provide reference for diagnosis of AIDS complicated with CNS infection. Method In our hospital between July 2019 and July 2020, 73 cases of suspected AIDS CNS infections in patients with cerebrospinal fluid mNGS parallel data were retrospectively analyzed, collect clinical manifestations, imaging data, cerebrospinal fluid examination Result,calculate infections, a positive analysis of infection type, etiology.The pathogens detected by routine etiology examination and mNGS were compared, which was consistent with the clinical diagnosis Finally, the application value of mNGS in these patients was evaluated. Result Among 73 patients, Headache, dyskinesia and fever were the main clinical manifestations, and the incidence rates were 69.9% (51/73), 54.8%（40/73）and 49.3% (36/73), respectively. Immune function was severely impaired, and CD4⁺T lymphocyte count was <200 cells/μl in 67 patients (91.8%). Finally, 46 (63.0%)patients were clinically diagnosed as CNS infection, and 46 patients received a total of 57 times of etiological diagnosis. The overall positive rate of mNGS combined with conventional examination was 82.5% (47/57), and the positive rate of mNGS was 64.9% (37/57) higher than that of conventional examination 42.1%(24/57), the difference was statistically significant (P=0.015). In 23 cases of virus infection, the positive rate of mNGS diagnosis was 87.0% (20/23), which was higher than that of conventional examination 34.8%(8/23), and the difference was statistically significant (P=0.007). Conclusion AIDS patients have impaired immune function,high rate of central nervous system infection and low positive rate of routine etiological examination,mNGS has better diagnostic value,combined with conventional examination method, mNGS has complementary advantages and can significantly improve the positive rate of etiological diagnosis, which is worthy of clinical promotion.

Key words: Acquired immune deficiency syndrome, Central nervous system infection, Cerebrospinal fluid, Routine etiological examination, Metagenomic next generation sequencing