The burden of nosocomial superinfections in a retrospective cohort study of critically ill COVID-19 patients

Abstract Objectives Viral respiratory infections can be complicated by bacterial superinfections. SARS-CoV-2 patients may suffer from superinfections, and negative effects of additional infections have been identified. When analysing hospital data, patients typically leave the facility of observatio...

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Main Authors: Anne Kathrin Lösslein, Paulina Ines Staus, Cynthia Beisert Carneiro, Martin Wolkewitz, Georg Häcker
Format: Article
Language:English
Published: BMC 2025-05-01
Series:BMC Infectious Diseases
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Online Access:https://doi.org/10.1186/s12879-025-10983-7
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author Anne Kathrin Lösslein
Paulina Ines Staus
Cynthia Beisert Carneiro
Martin Wolkewitz
Georg Häcker
author_facet Anne Kathrin Lösslein
Paulina Ines Staus
Cynthia Beisert Carneiro
Martin Wolkewitz
Georg Häcker
author_sort Anne Kathrin Lösslein
collection DOAJ
description Abstract Objectives Viral respiratory infections can be complicated by bacterial superinfections. SARS-CoV-2 patients may suffer from superinfections, and negative effects of additional infections have been identified. When analysing hospital data, patients typically leave the facility of observation, due to discharge or death, which leads to changes in the study cohort over time. This may distort the estimate of the impact of superinfection. Therefore, it is essential for the statistical analysis of hospital data to acknowledge this change of the risk set over time. We analysed superinfections in a retrospective cohort study with 268 critically ill patients, taking into account discharge and death as competing risks in the statistical analysis. Methods We evaluated bacterial respiratory infections and bloodstream infections and used multi-state statistical modelling to account for the different patient states. We calculated risks of superinfection, probability of discharge or death over time and analysed subgroups according to age and sex. Results The observed pathogen spectrum was mainly composed of Enterobacterales, Nonfermenters but also Staphylococcus aureus. We identified an elevated mortality due to bacterial infection of the respiratory tract or bloodstream infection (adj. cause-specific HR 1.7, CI 1.15–2.52) as well as a reduced discharge rate (adj. cause-specific HR 0.51, CI 0.36–0.73). Female patients showed a tendency to have a reduced risk of acquiring a superinfection (adj. subdistribution HR 0.71, CI 0.48–1.04), and in case of infection a higher mortality compared to male patients (interaction effect HR 1.49, CI 0.67–3.30). Conclusions The study accounts for competing risks and quantifies the risk of death associated with bacterial superinfection in critically ill COVID-19 patients. We observed an increased risk of death for patients who developed a superinfection, with Enterobacterales being the predominant agent. The results emphasize the need for microbiological sampling in SARS-CoV-2-infected patients. Clinical trial number German Clinical Trials Register number: DRKS00031367, registration date: 01.03.2023 ( https://drks.de/search/de/trial/DRKS00031367 ).
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spelling doaj-art-6cd74adffeed45e8bbdc90af0d73de3a2025-08-20T02:10:46ZengBMCBMC Infectious Diseases1471-23342025-05-0125111310.1186/s12879-025-10983-7The burden of nosocomial superinfections in a retrospective cohort study of critically ill COVID-19 patientsAnne Kathrin Lösslein0Paulina Ines Staus1Cynthia Beisert Carneiro2Martin Wolkewitz3Georg Häcker4Institute of Medical Microbiology and Hygiene, Medical Center and Faculty of Medicine, University of FreiburgInstitute of Medical Biometry and Statistics, Division Methods in Clinical Epidemiology, Medical Center, Faculty of Medicine, University of FreiburgInstitute of Medical Microbiology and Hygiene, Medical Center and Faculty of Medicine, University of FreiburgInstitute of Medical Biometry and Statistics, Division Methods in Clinical Epidemiology, Medical Center, Faculty of Medicine, University of FreiburgInstitute of Medical Microbiology and Hygiene, Medical Center and Faculty of Medicine, University of FreiburgAbstract Objectives Viral respiratory infections can be complicated by bacterial superinfections. SARS-CoV-2 patients may suffer from superinfections, and negative effects of additional infections have been identified. When analysing hospital data, patients typically leave the facility of observation, due to discharge or death, which leads to changes in the study cohort over time. This may distort the estimate of the impact of superinfection. Therefore, it is essential for the statistical analysis of hospital data to acknowledge this change of the risk set over time. We analysed superinfections in a retrospective cohort study with 268 critically ill patients, taking into account discharge and death as competing risks in the statistical analysis. Methods We evaluated bacterial respiratory infections and bloodstream infections and used multi-state statistical modelling to account for the different patient states. We calculated risks of superinfection, probability of discharge or death over time and analysed subgroups according to age and sex. Results The observed pathogen spectrum was mainly composed of Enterobacterales, Nonfermenters but also Staphylococcus aureus. We identified an elevated mortality due to bacterial infection of the respiratory tract or bloodstream infection (adj. cause-specific HR 1.7, CI 1.15–2.52) as well as a reduced discharge rate (adj. cause-specific HR 0.51, CI 0.36–0.73). Female patients showed a tendency to have a reduced risk of acquiring a superinfection (adj. subdistribution HR 0.71, CI 0.48–1.04), and in case of infection a higher mortality compared to male patients (interaction effect HR 1.49, CI 0.67–3.30). Conclusions The study accounts for competing risks and quantifies the risk of death associated with bacterial superinfection in critically ill COVID-19 patients. We observed an increased risk of death for patients who developed a superinfection, with Enterobacterales being the predominant agent. The results emphasize the need for microbiological sampling in SARS-CoV-2-infected patients. Clinical trial number German Clinical Trials Register number: DRKS00031367, registration date: 01.03.2023 ( https://drks.de/search/de/trial/DRKS00031367 ).https://doi.org/10.1186/s12879-025-10983-7Intensive care unitCOVID-19Healthcare associated infectionsSuperinfectionsCompeting risksHospital mortality
spellingShingle Anne Kathrin Lösslein
Paulina Ines Staus
Cynthia Beisert Carneiro
Martin Wolkewitz
Georg Häcker
The burden of nosocomial superinfections in a retrospective cohort study of critically ill COVID-19 patients
BMC Infectious Diseases
Intensive care unit
COVID-19
Healthcare associated infections
Superinfections
Competing risks
Hospital mortality
title The burden of nosocomial superinfections in a retrospective cohort study of critically ill COVID-19 patients
title_full The burden of nosocomial superinfections in a retrospective cohort study of critically ill COVID-19 patients
title_fullStr The burden of nosocomial superinfections in a retrospective cohort study of critically ill COVID-19 patients
title_full_unstemmed The burden of nosocomial superinfections in a retrospective cohort study of critically ill COVID-19 patients
title_short The burden of nosocomial superinfections in a retrospective cohort study of critically ill COVID-19 patients
title_sort burden of nosocomial superinfections in a retrospective cohort study of critically ill covid 19 patients
topic Intensive care unit
COVID-19
Healthcare associated infections
Superinfections
Competing risks
Hospital mortality
url https://doi.org/10.1186/s12879-025-10983-7
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