title: Assessment of severity of ICU-acquired pneumonia and association with etiology.
abstract: OBJECTIVE
  We evaluated the association between severity of illness and microbial etiology of ICU-acquired pneumonia to define if severity should be used to guide empiric antibiotic choices.
  
  
  METHODS
  Prospective observational study.
  
  
  METHODS
  ICUs of a university hospital.
  
  
  METHODS
  Three hundredy forty-three consecutive patients with ICU-acquired pneumonia clustered, according to the presence of multidrug resistant pathogens.
  
  
  METHODS
  None.
  
  
  RESULTS
  Two hundred eight patients had ventilator-associated pneumonia and 135 had nonventilator ICU-acquired pneumonia. We determined etiology in 217 patients (63%). The most frequent pathogens were Pseudomonas aeruginosa, Enterobacteriaceae, and methicillin-sensitive and methicillin-resistant Staphylococcus aureus. Fifty-eight patients (17%) had a multidrug-resistant causative agent. Except for a longer ICU stay and a higher rate of microbial persistence at the end of the treatment in the multidrug-resistant group, no differences were found in clinical and inflammatory characteristics, severity criteria, and mortality or survival between patients with and without multidrug-resistant pathogens, even after adjusting for potential confounders. Patients with higher severity scores (Acute Physiology and Chronic Health Evaluation II and Sepsis-related Organ Failure Assessment) and septic shock at onset of pneumonia had significantly lower 28- and 90-day survival and higher systemic inflammatory response. The results were similar when only patients with microbial diagnosis were considered, as well as when stratified into ventilator-associated pneumonia and nonventilator ICU-acquired pneumonia.
  
  
  CONCLUSIONS
  In patients with ICU-acquired pneumonia, severity of illness seems not to affect etiology. Risk factors for multidrug resistant, but not severity of illness, should be taken into account in selecting empiric antimicrobial treatment.
authors.affiliation: 1Servei de Pneumologia, Institut del Torax, Hospital Clinic, IDIBAPS, Universitat de Barcelona, Barcelona, Spain. 2Centro de Investigación Biomedica En Red-Enfermedades Respiratorias, Bunyola, Spain. 3Department of Pathophysiology and Transplantation, Università degli Studi di Milano, IRCCS Fondazione Ospedale Maggiore Policlinico Cà Granda, Milano, Italy. 4Department of Pulmonary Rehabilitation, Ospedale Villa Pineta, Pavullo nel Frignano, Modena, Italy. 5Department of Medicine, Winthrop University Hospital, Mineola, NY.
authors.forename: Marta
authors.initials: M
authors.lastname: Di Pasquale
authors.forename: Miquel
authors.initials: M
authors.lastname: Ferrer
authors.forename: Mariano
authors.initials: M
authors.lastname: Esperatti
authors.forename: Ernesto
authors.initials: E
authors.lastname: Crisafulli
authors.forename: Valeria
authors.initials: V
authors.lastname: Giunta
authors.forename: Gianluigi
authors.initials: G
authors.lastname: Li Bassi
authors.forename: Mariano
authors.initials: M
authors.lastname: Rinaudo
authors.forename: Francesco
authors.initials: F
authors.lastname: Blasi
authors.forename: Michael
authors.initials: M
authors.lastname: Niederman
authors.forename: Antoni
authors.initials: A
authors.lastname: Torres
mesh_terms: D003428:Cross Infection / Q000175:diagnosis*; D005260:Female; D006801:Humans; D007362:Intensive Care Units; D008297:Male; D008875:Middle Aged; D018410:Pneumonia, Bacterial / Q000175:diagnosis*; D053717:Pneumonia, Ventilator-Associated / Q000175:diagnosis*; D011446:Prospective Studies; D012720:Severity of Illness Index