[Source: Chest, full page: (LINK). Abstract, edited.]
Original Research| February 7, 2013

The Occurrence and Impact of Bacterial Organisms Complicating Critical Care Illness Associated with Influenza A(H1N1) infection

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

Author and Funding Information: Department of Medicine, Queen?s University, Kingston, muscedej@kgh.kari.net (Muscedere); Public Health Agency of Canada, marianna.ofner@hc-sc.gc.ca (Ofner); Winnipeg Health Sciences Centre and St. Boniface Hospital, University of Manitoba, akumar61@yahoo.com (Kumar); Sunnybrook Health Sciences Center, University of Toronto, jenalon@gmail.com (Long); Clinical Research Centre ?tienne Le Bel and Department of Medicine, Universit? de Sherbrooke, francoislamontagne@me.com (Lamontagne); Faculty of Health Sciences, McMaster University, debcook@mcmaster.ca (Cook); Mt. Sinai Hospital, University of Toronto, amcgeer@mtsinai.on.ca (McGeer); St. Michael?s Hospital, ChantC@smh.ca (Chant); St. Michael?s Hospital, MarshallJ@smh.ca (Marshall); Sainte-Justine Research Center, Universit? de Montr?al, philippe.jouvet@umontreal.ca (Jouvet); Sunnybrook Health Sciences Center, University of Toronto, Rob.Fowler@sunnybrook.ca (Fowler)

Corresponding Author: Dr. John Muscedere, Room 5-411, Angada 4, Kingston General Hospital, 76 Stuart Street, Kingston, Ontario, K7M 9H3 Email: muscedej@kgh.kari.net

CHEST. February 7, 2013doi:10.1378/chest.12-1861 - Published online



Although secondary infections are recognized as a cause of morbidity and mortality in seasonal influenza, their frequency, characteristics and associated clinical outcomes in Influenza A (H1N1)-related critical illness are unknown.


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


Among 681 patients the mean age was 47.9 years (standard deviation [SD] 15.1), APACHE II was 21.0 (9.9) and 573 (84.0%) were invasively mechanical ventilated (MV). Positive cultures were obtained in 259 (38.0 %): 77 (29.7%) prevalent; 115 (44.4%) ICU-acquired; 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 sp. 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 MV [mean(SD); 15.2 (10.7) vs. 10.7 (9.0), p< 0.0001], ICU stay [median(IQR);18.2 (12.5) vs. 10.8 (9.0) days, p< 0.0001], hospitalization [median(IQR); 30.7 (20.7) vs. 19.2 (17.4) days, p< 0.0001] and a trend towards increased hospital mortality (25.1% vs. 19.9%, p = 0.15). Patients with ICU-acquired positive cultures had worse outcomes compared to those with positive prevalent cultures or who were culture negative.


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