Purpose of review: The pathogenesis and impact of coinfection, in particular bacterial coinfection, in influenza are incompletely understood. This review summarizes results from studies on bacterial coinfection in the recent pandemic influenza outbreak.
Recent findings: Systemic immune mechanisms play a key role in the development of coinfection based on the complexity of the interaction of the host and the viral and bacterial pathogens. Several studies were performed to determine the point prevalence of bacterial coinfection in influenza. Coinfection in influenza is frequent in critically ill patients with Streptococcus pneumoniae being the most frequent bacterial pathogen and higher rates of potentially resistant pathogens over the years.
Summary: Bacterial pneumonia is certainly an influenza complication. The recent epidemiology findings have helped to partially resolve the contribution of different pathogens. Immunosuppression is a risk factor for bacterial coinfection in influenza, and the epidemiology of coinfection has changed over the years during the last influenza pandemic, and these recent findings should be taken into account during present outbreaks.
aMultidisciplinary Intensive Care Research Organization (MICRO)
bDepartment of Clinical Medicine, Trinity Centre for Health Sciences, Trinity College Dublin (TCD), St James's University Hospitals, Dublin, Ireland
cDepartment of Intensive Care
dDepartment of Medical Microbiology
eLaboratory of Experimental Intensive Care and Anesthesiology (LEICA), Academic Medical Center, Amsterdam, the Netherlands
Correspondence to Ignacio Martin-Loeches, Multidisciplinary Intensive Care Research Organization (MICRO), St James's University Hospital, Dublin 8, Ireland. Tel: +353 01 410 3000; e-mail: firstname.lastname@example.org