title: Influenza A and B co-infection: a case-control study and review of the literature.
abstract: Influenza virus infection remains a major cause of morbidity and mortality during winter seasons. Bacterial and virus co-infection is a commonly described situation in these patients. However, data on co-infection by influenza A and B viruses are lacking. In this study, we present the cases of co-infection by influenza A and B viruses during the winter season of 2014-2015 in our institution. We analyzed 2759 samples from 2111 patients and found that 625 samples corresponding to 609 patients were positive for influenza A or B virus. A total of 371 patients had influenza A, 228 had influenza B, and 10 (1.6 %) had influenza A and B virus detection in the same sample. The median age of co-infected patients was 78.6 years, and only one of the co-infected patients died because of the infection. Comparison with a control group of mono-infected patients revealed that co-infection was significantly associated with nosocomial acquisition [odds ratio (OR) = 4.5, 95 % confidence interval (CI) = 1.05-19.25, p = 0.042]. However, co-infection was not associated with worse outcome, previous underlying condition, or vaccination status. Multivariate analysis revealed that co-infection was not an independent risk factor for death and that no single risk factor could predict co-infection.
authors.affiliation: Department of Clinical Microbiology and Infectious Diseases, Hospital General Universitario Gregorio Marañón, Madrid, Spain. felipe.perez.garcia.87@gmail.com.
authors.forename: F
authors.initials: F
authors.lastname: Pérez-García
authors.affiliation: Department of Clinical Microbiology and Infectious Diseases, Hospital General Universitario Gregorio Marañón, Madrid, Spain.
authors.forename: V
authors.initials: V
authors.lastname: Vásquez
authors.affiliation: Department of Clinical Microbiology and Infectious Diseases, Hospital General Universitario Gregorio Marañón, Madrid, Spain.|Instituto de Investigación Biomédica Gregorio Marañón, Madrid, Spain.
authors.forename: V
authors.initials: V
authors.lastname: de Egea
authors.affiliation: Department of Clinical Microbiology and Infectious Diseases, Hospital General Universitario Gregorio Marañón, Madrid, Spain.
authors.forename: P
authors.initials: P
authors.lastname: Catalán
authors.affiliation: Department of Clinical Microbiology and Infectious Diseases, Hospital General Universitario Gregorio Marañón, Madrid, Spain.|Instituto de Investigación Biomédica Gregorio Marañón, Madrid, Spain.
authors.forename: B
authors.initials: B
authors.lastname: Rodríguez-Sánchez
authors.affiliation: Department of Clinical Microbiology and Infectious Diseases, Hospital General Universitario Gregorio Marañón, Madrid, Spain. ebouza@microb.net.|Instituto de Investigación Biomédica Gregorio Marañón, Madrid, Spain. ebouza@microb.net.|Department of Medicine, Universidad Complutense de Madrid, Madrid, Spain. ebouza@microb.net.|CIBER Enfermedades Respiratorias (CB06/06/0058), Madrid, Spain. ebouza@microb.net.
authors.forename: E
authors.initials: E
authors.lastname: Bouza
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D060085:Coinfection; D015897:Comorbidity; D005260:Female; D006801:Humans; D009980:Influenza A virus / Q000145:classification / Q000235:genetics; D009981:Influenza B virus / Q000145:classification / Q000235:genetics; D007251:Influenza, Human / Q000175:diagnosis / Q000453:epidemiology* / Q000401:mortality / Q000821:virology*; D007902:Length of Stay; D008297:Male; D008875:Middle Aged; D009026:Mortality; D016017:Odds Ratio; D063868:Patient Outcome Assessment; D012189:Retrospective Studies; D012307:Risk Factors