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. 2025 May 6;15(1):61.
doi: 10.1186/s13613-025-01462-y.

Nosocomial lower respiratory tract infections in patients with immunosuppression: a cohort study

Luis Felipe Reyes #  1   2   3 , Natalia Sanabria-Herrera #  4   5 , Saad Nseir  6 , Otavio T Ranzani  7   8 , Pedro Povoa  9   10   11 , Emilio Diaz  12 , Marcus J Schultz  13   14 , Alejandro Rodríguez  15 , Cristian C Serrano-Mayorga  4   5   16 , Gennaro De Pascale  17 , Paolo Navalesi  18   19 , Szymon Skoczynski  20 , Mariano Esperatti  21 , Luis Miguel Coelho  22 , Andrea Cortegiani  23   24 , Stefano Aliberti  25   26   27 , Anselmo Caricato  17 , Helmut J F Salzer  28   29   30 , Adrian Ceccato  31   32   33   34 , Rok Civljak  35 , Paolo Maurizio Soave  17 , Charles-Edouard Luyt  36 , Pervin Korkmaz Ekren  37 , Fernando Rios  38 , Joan Ramon Masclans  39 , Judith Marin  40 , Silvia Iglesias-Moles  41 , Stefano Nava  42   43 , Davide Chiumello  44 , Lieuwe D J Bos  13 , Antonio Artigas  45 , Filipe Froes  46 , David Grimaldi  47 , Mauro Panigada  48 , Fabio Silvio Taccone  47 , Massimo Antonelli  17 , Antoni Torres  49 , Ignacio Martin-Loeches  50 ; European Network for ICU-Related Respiratory Infections (ENIRRIs) European Respiratory Society-Clinical Research Collaboration Investigators
Affiliations

Nosocomial lower respiratory tract infections in patients with immunosuppression: a cohort study

Luis Felipe Reyes et al. Ann Intensive Care. .

Abstract

Background: This post-hoc analysis of a multinational, multicenter study aimed to describe and compare clinical characteristics, microbiology, and outcomes between immunosuppressed and non-immunosuppressed patients with nosocomial lower respiratory tract infections (nLRTI). The study utilized data from the European Network for ICU-related Respiratory Infections, including 1,060 adult ICU patients diagnosed with nLRTI. Descriptive statistics were used to compare baseline characteristics and pathogen distribution between groups. A Cox proportional hazards model stratified by immunosuppression status was applied to assess 28-day mortality risk, adjusting for disease severity and key clinical variables.

Results: Immunosuppression was observed in 24.9% (264/1060) of the patients, and oncological conditions were the most common etiology of immunosuppression. Chronic pulmonary and cardiovascular diseases were the most frequent comorbidities. In both groups, Pseudomonas aeruginosa was the predominant microorganism, particularly affecting patients with immunosuppression (25.3% vs. 16.7%, p = 0.032). Cox regression model adjusted for disease severity (SAPS II), polytraumatized status, altered consciousness, and postoperative status, SAPS II remained a strong independent predictor of mortality, with each one-point increase associated with a 2.3% higher risk of death (HR: 1.023, 95% CI 1.017-1.030, p < 0.001). The analysis also revealed significant heterogeneity in mortality risk among immunosuppressed patients, with hematological malignancies, recent chemotherapy, and bone marrow transplantation associated with the highest mortality.

Conclusions: Immunosuppressed patients had a lower adjusted survival probability compared to non-immunosuppressed patients. Moreover, P. aeruginosa was the most frequently identified etiological pathogen in immunosuppressed patients.

Keywords: Critical care; Immunosuppression; Nosocomial lower respiratory tract infections.

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Conflict of interest statement

Declarations. Ethics approval and consent to participate: This study was conducted in accordance with the principles of the Declaration of Helsinki. The research protocol was approved by the Institutional Review Board (IRB)—Comité Ètic d'Investigació Clínica, with the registry number HCB/2020/0370. Given the retrospective and observational nature of the study, the need for informed consent was waived by the ethics committee. Data were anonymized prior to analysis to ensure the confidentiality and privacy of participants. Consent for publication: Not applicable. Competing interests: All authors have no conflict of interest.

Figures

Fig. 1
Fig. 1
Study Flowchart. Flowchart of included patients diagnosed with ICU-related respiratory infections and clinical outcomes. *Please note that patients may have more than one state of immunosuppression; for further details, refer to Supplementary Fig. 1 and Supplementary Table 1, which provide additional information on this aspect
Fig. 2
Fig. 2
Identified microorganisms in A the Immunosuppressed and B the Non-Immunosuppressed group. Distribution of identified microorganisms in both immunosuppressed and non-immunosuppressed patients diagnosed with ICU-related respiratory infections. Specific pathogens and proportions are available in Supplementary Table 2
Fig. 3
Fig. 3
Kaplan–Meier Survival Curve at 28 days, Adjusted for Disease Severity Using SAPS II Score. Kaplan–Meier survival analysis comparing 28-day survival between immunosuppressed and non-immunosuppressed patients, adjusted for disease severity based on SAPS II scores
See this image and copyright information in PMC

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