Original Research: Critical Care |

The Occurrence and Impact of Bacterial Organisms Complicating Critical Care Illness Associated With 2009 Influenza A(H1N1) InfectionSuperinfection in the Critically Ill with H1N1

John Muscedere, MD; Marianna Ofner, PhD; Anand Kumar, MD; Jennifer Long, MSc; Francois Lamontagne, MD; Deborah Cook, MD; Allison McGeer, MD; Clarence Chant, PharmD; John Marshall, MD; Philippe Jouvet, MD, PhD; Robert Fowler; for the ICU-FLU Group* and the Canadian Critical Care Trials Group
Author and Funding Information

From the Department of Medicine (Dr Muscedere), Queen’s University, Kingston, ON; the Public Health Agency of Canada (Dr Ofner), Ottawa, ON and Winnipeg, MB; the Winnipeg Health Sciences Centre and St. Boniface Hospital (Dr Kumar), University of Manitoba, Winnipeg, MB; the Sunnybrook Health Sciences Center (Ms Long and Dr Fowler), University of Toronto, Toronto, ON; the Clinical Research Centre Étienne Le Bel and Department of Medicine (Dr Lamontagne), Université de Sherbrooke, Sherbrooke, QC; the Faculty of Health Sciences (Dr Cook), McMaster University, Hamilton, ON; Mt. Sinai Hospital (Dr McGeer), University of Toronto, Toronto, ON; St. Michael’s Hospital (Drs Chant and Marshall), Toronto, ON; and the Sainte-Justine Research Center (Dr Jouvet), Université de Montréal, QC, Canada.

Correspondence to: John Muscedere, MD, Room 5-411, Angada 4, Kingston General Hospital, 76 Stuart St, Kingston, ON, K7M 9H3, Canada; e-mail: muscedej@kgh.kari.net


A complete list of study participants is located in e-Appendix 1.

Funding/Support: The authors have reported to CHEST that no funding was received for this study.

Reproduction of this article is prohibited without written permission from the American College of Chest Physicians. See online for more details.

Chest. 2013;144(1):39-47. doi:10.1378/chest.12-1861
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Background:  Although secondary infections are recognized as a cause of morbidity and mortality in seasonal influenza, their frequency, characteristics, and associated clinical outcomes in 2009 influenza A(H1N1) (A[H1N1])-related critical illness are unknown.

Methods:  In a prospective cohort of adult patients admitted to Canadian ICUs with influenza A(H1N1) infection, the frequency and associated clinical outcomes of prevalent (culture taken within 72 h of ICU admission) and ICU-acquired (culture taken after 72 h from ICU admission) positive bacterial cultures were determined.

Results:  Among 681 patients, the mean age was 47.9 years (SD, 15.1), APACHE (Acute Physiology and Chronic Health Examination) II score was 21.0 (9.9), and 573 patients (84.0%) were invasively mechanically ventilated. Positive cultures were obtained in 259 patients (38.0%): 77 (29.7%) had prevalent, 115 (44.4%) had ICU-acquired, and 40 (15.4%) had both; culture date was unavailable in 27 (10.4%). The most common bacterial organisms isolated were coagulase-negative staphylococci, Staphylococcus aureus, Pseudomonas species, and Streptococcus pneumoniae. Antibiotics were prescribed in 661 (97.1%), with 3.8 (1.9) prescriptions per patient. Patients with any positive culture had longer days of mechanical ventilation (mean [SD], 15.2 [10.7] vs 10.7 [9.0]; P < .0001), ICU stay (median [interquartile range (IQR)], 18.2 [12.5] days vs 10.8 [9.0] days, P < .0001), and hospitalization (median [IQR], 30.7 [20.7] days vs 19.2 [17.4] days, P < .0001) and a trend toward increased hospital mortality (25.1% vs 19.9%, P = .15). Patients with ICU-acquired positive cultures had worse outcomes compared with those with positive prevalent cultures or who were culture-negative.

Conclusion:  Culture-based evidence of secondary infections commonly complicates A(H1N1)-related critical illness and is associated with worse clinical outcomes despite nearly ubiquitous antibiotic administration.

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