Intensive Care Medicine

, Volume 43, Issue 1, pp 48–58 | Cite as

Increased incidence of co-infection in critically ill patients with influenza

  • Ignacio Martin-LoechesEmail author
  • Marcus J Schultz
  • Jean-Louis Vincent
  • Francisco Alvarez-Lerma
  • Lieuwe D. Bos
  • Jordi Solé-Violán
  • Antoni Torres
  • Alejandro Rodriguez



Co-infection is frequently seen in critically ill patients with influenza, although the exact rate is unknown. We determined the rate of co-infection, the risk factors and the outcomes associated with co-infection in critically ill patients with influenza over a 7-year period in 148 Spanish intensive care units (ICUs).


This was a prospective, observational, multicentre study. Influenza was diagnosed using the polymerase chain reaction. Co-infection had to be confirmed using standard bacteriological tests. The primary endpoint of this analysis was the presence of community-acquired co-infection, with secondary endpoints including ICU, 28-day and hospital mortality.


Of 2901 ICU patients diagnosed with influenza, 482 (16.6 %) had a co-infection. The proportion of cases of co-infection increased from 11.4 % (110/968) in 2009 to 23.4 % (80/342) in 2015 (P < 0.001). Compared with patients without co-infection, patients with co-infection were older [adjusted odds ratio (aOR) 1.1, 95 % confidence interval 1.1–1.2; P < 0.001] and were more frequently immunosuppressed due to existing HIV infection (aOR 2.6 [1.5–4.5]; P < 0.001) or preceding medication (aOR 1.4 [1.1–1.9]; P = 0.03). Co-infection was an independent risk factor for ICU mortality (aOR 1.4 [1.1–1.8]; P < 0.02), 28-day mortality (aOR 1.3 [1.1–1.7]; P = 0.04) and hospital mortality (aOR 1.9 [1.5–2.5]; P < 0.001).


Co-infection in critically ill patients with influenza has increased in recent years. In this Spanish cohort, age and immunosuppression were risk factors for co-infection, and co-infection was an independent risk factor for ICU, 28-day and hospital mortality.


Influenza Co-infection Risk factors Outcome Intensive care 



The authors are grateful to Zieta O’Hagan for language editing.

Compliance with ethical standards

Conflicts of interest

All of the authors declare that no conflict of interest exists.

Role of funding source

The study funder (Spanish Society of Critical Care—SEMICYUC) had no role in the study design, data collection, data analysis, data interpretation, or writing of the report. The corresponding author (IML) had full access to all the data in the study and final responsibility for the decision to submit for publication.

Ethics committee approval

The institutional review board of Joan XXIII University Hospital approved the original study (IRBref#11809).

Supplementary material

134_2016_4578_MOESM1_ESM.docx (12 kb)
Supplementary material 1 (DOCX 11 kb)


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Copyright information

© Springer-Verlag Berlin Heidelberg and ESICM 2016

Authors and Affiliations

  • Ignacio Martin-Loeches
    • 1
    • 2
    Email author
  • Marcus J Schultz
    • 3
  • Jean-Louis Vincent
    • 4
  • Francisco Alvarez-Lerma
    • 5
  • Lieuwe D. Bos
    • 3
  • Jordi Solé-Violán
    • 6
  • Antoni Torres
    • 7
  • Alejandro Rodriguez
    • 8
    • 9
  1. 1.Multidisciplinary Intensive Care Research Organization (MICRO), Wellcome Trust-HRB Clinical Research, Department of Clinical Medicine, Trinity Centre for Health SciencesSt James’s University HospitalDublinIreland
  2. 2.CIBEResMadridSpain
  3. 3.Department of Intensive CareAcademic Medical CenterAmsterdamThe Netherlands
  4. 4.Department of Intensive Care, Erasme HospitalUniversité libre de BruxellesBrusselsBelgium
  5. 5.Service of Intensive Care Medicine, Parc de Salut MarUniversitat Autonoma de BarcelonaBarcelonaSpain
  6. 6.Intensive Care UnitHospital Universitario Dr. Negrín, CIBERESLas Palmas de Gran CanariaSpain
  7. 7.Hospital Clinic BarcelonaUniversidad Barcelona, CIBERESBarcelonaSpain
  8. 8.Centro de Investigación Biomédica En Red de Enfermedades Respiratorias (CIBERES)MadridSpain
  9. 9.Critical Care Department, Institut d’Investigació Sanitària Pere Virgili (IISPV), Joan XXIII University HospitalUniversitat Rovira i VirgiliTarragonaSpain

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