Clinical characteristics of

Background: Methods: We collected and retrospectively analyzed 20 cases of PCP diagnosed in HIV-negative patients at Hangzhou TCM Hospital Affiliated to Zhejiang Chinese Medical University. Results: All cases were diagnosed using metagenomic next-generation sequencing (mNGS) of bronchoalveolar lavage (BAL). Of all 20 patients, 11 were men and nine were women. The median age was 66.5 (range, 18-83) years old. Three out of 20 patients had no immunosuppressive background, while 17 were exposed to immunosuppressants due to different diseases. Among them, four had solid malignancies, four had kidney disease, three had hematological malignancies, two had skin diseases, one had thrombocytopenia, one had rheumatoid arthritis, one had anaphylactoid purpura and one had knee arthritis. All patients had not received prophylactic drugs for PCP. All patients underwent antimicrobial treatment, 16 cases received glucocorticoid treatment, and seven underwent mechanical ventilation. A total of six out of 20 patients died. Bivariate Pearson's test revealed a negative correlation between patients' oxygenation index and age (r=-0.493, P=0.03). Serum lactate dehydrogenase (LDH) levels were positively correlated with serum creatinine levels (r=0.557, P=0.01). LDH levels were positively correlated with the time between symptom onset and oral administration of compound sulfamethoxazole (SMZ-TMP) (r=0.477, P=0.03). There was also a positive correlation between creatinine levels and the time to oral SMZ-TMP administration (r=0.607, P=0.005). Conclusions: HIV-negative patients with PCP have atypical clinical symptoms and a high mortality rate. mNGS technology may facilitate early diagnosis based on its rapid turnaround time. To reduce mortality, SMZ-TMP drug treatment should be initiated promptly once PCP is considered clinically.