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Journal Article

Publication Date



Influenza and Other Respiratory Viruses




AIM: Co-infecting bacterial pathogens are a major cause of morbidity and mortality in influenza. However, there remains a paucity of literature on the magnitude of co-infection in influenza patients.

METHOD: A systematic search of MeSH, Cochrane Library, Web of Science, SCOPUS, EMBASE, and PubMed was performed. Studies of humans in which all individuals had laboratory confirmed influenza, and all individuals were tested for an array of common bacterial species, met inclusion criteria.

RESULTS: Twenty-seven studies including 3,215 participants met all inclusion criteria. Common etiologies were defined from a subset of eight articles. There was high heterogeneity in the results (I(2) = 95%), with reported co-infection rates ranging from 2% to 65%. Though only a subset of papers were responsible for observed heterogeneity, subanalyses and meta-regression analysis found no study characteristic that was significantly associated with co-infection. The most common co-infecting species were Streptococcus pneumoniae and Staphylococcus aureus, which accounted for 35% (95% CI, 14%-56%) and 28% (95% CI, 16%-40%) of infections, respectively; a wide range of other pathogens caused the remaining infections. An assessment of bias suggested that lack of small-study publications may have biased the results.

CONCLUSIONS: The frequency of co-infection in the published studies included in this review suggests that though providers should consider possible bacterial co-infection in all patients hospitalized with influenza, they should not assume all patients are co-infected and be sure to properly treat underlying viral processes. Further, high heterogeneity suggests additional large-scale studies are needed to better understand the etiology of influenza bacterial co-infection. This article is protected by copyright. All rights reserved.


Reproduced with permission of John Wiley & Sons. Influenza and Other Respiratory Viruses

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