title: Bacterial complications of respiratory tract viral illness: a comprehensive evaluation.
abstract: BACKGROUND
  Respiratory tract infection is one of the most common reasons for hospitalization among adults, and recent evidence suggests that many of these illnesses are associated with viruses. Although bacterial infection is known to complicate viral infections, the frequency and impact of mixed viral-bacterial infections has not been well studied.
  
  
  METHODS
  Adults hospitalized with respiratory illness during 3 winters underwent comprehensive viral and bacterial testing. This assessment was augmented by measuring the serum level of procalcitonin (PCT) as a marker of bacterial infection. Mixed viral-bacterial infection was defined as a positive viral test result plus a positive bacterial assay result or a serum PCT level of ≥ 0.25 ng/mL on admission or day 2 of hospitalization.
  
  
  RESULTS
  Of 842 hospitalizations (771 patients) evaluated, 348 (41%) had evidence of viral infection. A total of 212 hospitalizations (61%) involved patients with viral infection alone. Of the remaining 136 hospitalizations (39%) involving viral infection, results of bacterial tests were positive in 64 (18%), and PCT analysis identified bacterial infection in an additional 72 (21%). Subjects hospitalized with mixed viral-bacterial infections were older and more commonly received a diagnosis of pneumonia. Over 90% of hospitalizations in both groups involved subjects who received antibiotics. Notably, 4 of 10 deaths among subjects hospitalized with viral infection alone were secondary to complications of Clostridium difficile colitis.
  
  
  CONCLUSIONS
  Bacterial coinfection is associated with approximately 40% of viral respiratory tract infections requiring hospitalization. Patients with positive results of viral tests should be carefully evaluated for concomitant bacterial infection. Early empirical antibiotic therapy for patients with an unstable condition is appropriate but is not without risk.
authors: Rochester General Hospital, Rochester, NY, USA. ann.falsey@rochestergeneral.org
authors: Ann R
authors: AR
authors: Falsey
authors: Kenneth L
authors: KL
authors: Becker
authors: Andrew J
authors: AJ
authors: Swinburne
authors: Eric S
authors: ES
authors: Nylen
authors: Maria A
authors: MA
authors: Formica
authors: Patricia A
authors: PA
authors: Hennessey
authors: Mary M
authors: MM
authors: Criddle
authors: Derick R
authors: DR
authors: Peterson
authors: Andrea
authors: A
authors: Baran
authors: Edward E
authors: EE
authors: Walsh
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001424:Bacterial Infections / Q000453:epidemiology* / Q000382:microbiology; D060085:Coinfection / Q000453:epidemiology / Q000382:microbiology / Q000821:virology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D012141:Respiratory Tract Infections / Q000382:microbiology* / Q000821:virology*; D014777:Virus Diseases / Q000150:complications* / Q000821:virology
keywords: bacterial infection; pneumonia; procalcitonin; virus
references: Arch Pathol Lab Med. 2010 Feb;134(2):235-43
references: 20121613
references: Virol J. 2011 Nov 03;8:501
references: 22050645
references: Clin Infect Dis. 2005 Aug 1;41(3):345-51
references: 16007532
references: J Infect Dis. 2012 Jul 1;206(1):56-62
references: 22529314
references: Clin Infect Dis. 2011 May;52 Suppl 4:S296-304
references: 21460288
references: Crit Care Med. 2008 Mar;36(3):941-52
references: 18431284
references: Infect Control Hosp Epidemiol. 2005 Mar;26(3):273-80
references: 15796280
references: J Clin Microbiol. 2003 Sep;41(9):4160-5
references: 12958241
references: Arch Intern Med. 2011 Aug 8;171(15):1322-31
references: 21824946
references: Am J Med. 2005 Mar;118(3):285-91
references: 15745727
references: J Infect Dis. 2010 Oct 15;202(8):1287-95
references: 20822454
references: Arch Intern Med. 2008 Dec 8;168(22):2489-96
references: 19064834
references: Arch Intern Med. 2007 Feb 26;167(4):354-60
references: 17242309
references: J Clin Microbiol. 2011 Jul;49(7):2449-53
references: 21508156
references: J Clin Microbiol. 2008 Feb;46(2):727-31
references: 18094125
references: Lancet Infect Dis. 2006 May;6(5):303-12
references: 16631551
references: Br J Pharmacol. 2010 Jan 1;159(2):253-64
references: 20002097
references: Infect Control Hosp Epidemiol. 2010 Nov;31(11):1177-83
references: 20923284
references: J Clin Microbiol. 2008 Feb;46(2):533-9
references: 18057136
references: BMC Infect Dis. 2007 Mar 02;7:10
references: 17335562
references: J Am Geriatr Soc. 1992 Feb;40(2):115-9
references: 1740594
references: PLoS One. 2011 Apr 29;6(4):e18890
references: 21573031
references: Int J Chron Obstruct Pulmon Dis. 2012;7:127-35
references: 22399852
references: Crit Care Med. 2012 May;40(5):1487-98
references: 22511131
references: Eur Respir J. 2006 Apr;27(4):795-800
references: 16585087
references: N Engl J Med. 2010 May 6;362(18):1708-19
references: 20445182
references: J Clin Invest. 1959 Jan;38(1 Part 2):213-65
references: 13620784
references: N Engl J Med. 2005 Apr 28;352(17):1749-59
references: 15858184
references: Chest. 2011 Jun;139(6):1410-1418
references: 21030489
references: Chest. 2010 Oct;138(4):896-904
references: 20435659