title: Occult bloodstream infections in adults: a "benign" entity.
abstract: BACKGROUND
  Patients with septic episodes whose blood cultures turn positive after being sent home from emergency departments (EDs) are recognized as having occult bloodstream infections (BSI). The incidence, etiology, clinical circumstances, and outcome of occult BSI in children are well known, but, to our knowledge, data in adult patients are scarce. We analyzed the episodes of occult BSI in adult patients at our institution.
  
  
  METHODS
  This is a retrospective cohort study (September 2010 to September 2012), in adult patients discharged from the ED in whom blood cultures turned positive. Patients were evaluated according to a preestablished protocol.
  
  
  RESULTS
  We recorded 4025 cases of significant BSI in the ED and 113 patients with adult occult BSI. In other words, the incidence of occult BSI in the ED was 2.8 per 100 episodes. The predominant microorganisms were gram-negative bacteria (57%); Escherichia coli was the most common (41%), followed by gram-positive bacteria (29%), anaerobes (6.9%), polymicrobial (6.1%), and yeasts (0.8%). The most frequent suspected origin was urinary tract infection (53%), and most infections were community acquired (63.7%). Of the 105 patients that we were able to trace, 54 (42.5%) were asymptomatic and were receiving adequate antibiotic treatment at the time of the call, and 65 (51.2%) had persistent fever or were not receiving adequate antibiotic treatment.
  
  
  CONCLUSIONS
  Occult BSI is relatively common in patients in the adult ED. Despite the need for readmission of a fairly high proportion of patients, occult BSI behaves as a relatively benign entity.
authors.affiliation: Clinical Microbiology and Infectious Diseases, Hospital General Universitario Gregorio, Marañón, Madrid, Spain. Electronic address: marcelag.delv@gmail.com.
authors.forename: Marcela
authors.initials: M
authors.lastname: González-Del Vecchio
authors.affiliation: Clinical Microbiology and Infectious Diseases, Hospital General Universitario Gregorio, Marañón, Madrid, Spain.
authors.forename: Eleonora
authors.initials: E
authors.lastname: Bunsow
authors.affiliation: Clinical Microbiology and Infectious Diseases, Hospital General Universitario Gregorio, Marañón, Madrid, Spain.
authors.forename: Carlos
authors.initials: C
authors.lastname: Sánchez-Carrillo
authors.affiliation: Emergency Department. Hospital General Universitario Gregorio, Marañón, Madrid, Spain.
authors.forename: Eugenia
authors.initials: E
authors.lastname: Garcia Leoni
authors.affiliation: Clinical Microbiology and Infectious Diseases, Hospital General Universitario Gregorio, Marañón, Madrid, Spain; Medicine Department, School of Medicine, Universidad Complutense de Madrid, Madrid, Spain.; Instituto de Investigación Sanitaria Gregorio, Marañón, Madrid, Spain; CIBER Enfermedades Respiratorias-CIBERES (CB06/06/0058), Madrid, Spain.
authors.forename: Marta
authors.initials: M
authors.lastname: Rodríguez-Créixems
authors.affiliation: Clinical Microbiology and Infectious Diseases, Hospital General Universitario Gregorio, Marañón, Madrid, Spain; Medicine Department, School of Medicine, Universidad Complutense de Madrid, Madrid, Spain.; Instituto de Investigación Sanitaria Gregorio, Marañón, Madrid, Spain; CIBER Enfermedades Respiratorias-CIBERES (CB06/06/0058), Madrid, Spain. Electronic address: Emilio.bouza@gmail.com.
authors.forename: Emilio
authors.initials: E
authors.lastname: Bouza
mesh_terms: D000328:Adult; D000368:Aged; D016470:Bacteremia / Q000175:diagnosis* / Q000453:epidemiology / Q000382:microbiology; D017714:Community-Acquired Infections / Q000175:diagnosis / Q000453:epidemiology / Q000382:microbiology; D004636:Emergency Service, Hospital / Q000706:statistics & numerical data; D005260:Female; D016905:Gram-Negative Bacterial Infections / Q000175:diagnosis / Q000453:epidemiology / Q000382:microbiology; D016908:Gram-Positive Bacterial Infections / Q000175:diagnosis / Q000453:epidemiology / Q000382:microbiology; D006784:Hospitals, Teaching / Q000706:statistics & numerical data; D006801:Humans; D008297:Male; D008875:Middle Aged; D010351:Patient Discharge / Q000706:statistics & numerical data; D012189:Retrospective Studies