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BioMed Research International
Volume 2013 (2013), Article ID 376219, 6 pages
http://dx.doi.org/10.1155/2013/376219
Clinical Study

Secondary Bacterial Infections in Patients with Seasonal Influenza A and Pandemic H1N1

1Division of Clinical Microbiology F 72, Karolinska Institutet, Karolinska University Hospital, Huddinge, 141 86 Stockholm, Sweden
2Department of Infectious Diseases, Karolinska University Hospital, Huddinge, 141 86 Stockholm, Sweden

Received 2 April 2013; Revised 10 June 2013; Accepted 10 June 2013

Academic Editor: Rumiana Koynova

Copyright © 2013 Karin Liderot et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The aim of the present study is to analyse the secondary bacterial infections in a large group of patients with seasonal influenza A and influenza A(H1N1) pdm09. Patients diagnosed with seasonal influenza A and influenza A(H1N1) pdm09 between 2005 and 2009 were enrolled in the study. Data was retrieved from medical records and laboratory information systems (LIS). In total, 1094 patients with laboratory confirmed influenza were studied. There were 352 patients with seasonal influenza A and 742 patients with influenza A(H1N1) pdm09. The patients with influenza A were older and had higher comorbidity than patients with influenza A(H1N1) pdm09 ( and , resp.). Hospital admission was higher in influenza A group ( ). In contrast, ICU admission was higher in patients with influenza A(H1N1) pdm09 than influenza A patients ( ). There were higher numbers of bacterial samples taken and culture positivity in patients with influenza A than patients with influenza A(H1N1) pdm09 ( and , resp.). In both groups, the majority of the patients with positive bacterial cultures had underlying diseases. The present study shows that the patient characteristics and the frequency of secondary bacterial infections were different in patients with seasonal influenza A and in patients with influenza A(H1N1) pdm09.