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 (P<0.05) 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.