title: Effect of adequate single-drug vs combination antimicrobial therapy on mortality in Pseudomonas aeruginosa bloodstream infections: a post Hoc analysis of a prospective cohort.
abstract: BACKGROUND
  Empirical combination therapy is recommended for patients with known or suspected Pseudomonas aeruginosa (PA) infection as a means to decrease the likelihood of administering inadequate antimicrobial treatment, to prevent the emergence of resistance, and to achieve a possible additive or even synergistic effect.
  
  
  METHODS
  We performed a post hoc analysis of patients with PA bloodstream infections from a published prospective cohort. Mortality was compared in patients treated with adequate empirical and definitive combination therapy (AECT, ADCT), and adequate empirical and definitive single-drug therapy (AESD, ADSD). Confounding was controlled by Cox regression analysis, and a propensity score for receiving AECT or ADCT was also used.
  
  
  RESULTS
  The final cohort comprised 593 patients with a single episode of PA bacteremia. The 30-day mortality was 30% (176 patients); 76 patients (13%) died during the first 48 hours. The unadjusted probabilities of survival until day 30 were 69.4% (95% confidence interval [CI], 59.1-81.6) for the patients receiving AECT, 73.5% (95% CI, 68.4%-79.0%) for the AESD group, and 66.7% (95% CI, 61.2%-72.7%) for patients who received inadequate empirical therapy (P = .17, log-rank test). After adjustment for confounders, the AESD group (adjusted hazard ratio [AHR], 1.17; 95% CI, .70-1.96; P = .54) and patients who received ADSD (AHR, 1.34; 95% CI, .73-2.47; P = .35) showed no association with 30-day mortality compared with the AECT and ADCT groups, respectively.
  
  
  CONCLUSIONS
  These results suggests that treatment with combination antimicrobial therapy did not reduce the mortality risk compared with single-drug therapy in PA bloodstream infections.
authors.affiliation: Servicio de Enfermedades Infecciosas, Hospital Universitario de Bellvitge-IDIBELL, Barcelona. cpena@bellvitgehospital.cat
authors.forename: Carmen
authors.initials: C
authors.lastname: Peña
authors.forename: Cristina
authors.initials: C
authors.lastname: Suarez
authors.forename: Alain
authors.initials: A
authors.lastname: Ocampo-Sosa
authors.forename: Javier
authors.initials: J
authors.lastname: Murillas
authors.forename: Benito
authors.initials: B
authors.lastname: Almirante
authors.forename: Virginia
authors.initials: V
authors.lastname: Pomar
authors.forename: Manuela
authors.initials: M
authors.lastname: Aguilar
authors.forename: Ana
authors.initials: A
authors.lastname: Granados
authors.forename: Esther
authors.initials: E
authors.lastname: Calbo
authors.forename: Jesús
authors.initials: J
authors.lastname: Rodríguez-Baño
authors.forename: Fernando
authors.initials: F
authors.lastname: Rodríguez
authors.forename: Fe
authors.initials: F
authors.lastname: Tubau
authors.forename: Antonio
authors.initials: A
authors.lastname: Oliver
authors.forename: Luis
authors.initials: L
authors.lastname: Martínez-Martínez
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D016470:Bacteremia / Q000188:drug therapy* / Q000401:mortality*; D015331:Cohort Studies; D004359:Drug Therapy, Combination / Q000379:methods; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011552:Pseudomonas Infections / Q000188:drug therapy* / Q000401:mortality*; D016019:Survival Analysis; D016896:Treatment Outcome
chemical_list: D000900:Anti-Bacterial Agents
keywords: P. aeruginosa; bloodstream infections; combination antimicrobial therapy; mortality