Clinical characteristics of Pneumocystis jirovecii pneumonia in non-HIV patients: a retrospective study

Objective To investigate the clinical characteristics and identify risk factors for severe Pneumocystis jirovecii pneumonia (PJP) in human immunodeficiency virus (HIV) -negative patients. Methods This retrospective study included 39 non-HIV PJP patients diagnosed by next-generation sequencing (NGS) of bronchoalveolar lavage fluid (BALF) at Taizhou Municipal Hospital between June 2019 and March 2025. Patients were divided into severe (n=18) and non-severe (n=21) groups based on disease severity. Continuous variables were analyzed using Student’s t-test or Mann-Whitney U test, while categorical variables were compared with Fisher’s exact test. Variables showing statistical significance (P0.05) were subsequently included in multivariable logistic regression analysis to identify differences in clinical characteristics between the two groups. Results The mean age of the entire cohort was 62.59 ± 12.59 years, and 64.10% (25/39) were male. The severe group had significantly higher case-fatality rate than the non-severe group (61.1% vs. 0%, P 0.001). Serum procalcitonin (PCT) 0.285 (0.113, 0.643) vs. 0.070 (0.045, 0.110) ng/mL; P = 0.003 and lactate dehydrogenase (LDH) 554.00 (465.25, 702.00) vs. 269.00 (246.50, 378.00) IU/L; P 0.001 levels were significantly elevated in the severe group compared with the non-severe group. BALF-based NGS detected co-infections in 76.92% (30/39) of cases, predominantly bacteria (35.90%, 14/39) and Cytomegalovirus (CMV) (30.77%, 12/39) infections. The severe group showed significantly higher CMV co-infection rates than the non-severe group (55.56% vs. 9.52%, P = 0.006). Multivariable logistic regression analysis revealed that elevated LDH levels (OR = 1.863, 95% CI 1.153-3.009; P = 0.011) and CMV co-infection (OR = 11.477, 95% CI 1.186-111.109; P = 0.035) were independent risk factors for severe PJP. Conclusions Pneumocystis jirovecii pneumonia in non-HIV demonstrated a substantial case-fatality rate. BALF-based NGS may facilitate the detection of co-infections. Elevated LDH levels and CMV co-infection emerged as independent predictors of progression to severe PJP.