title: Impact of definitive therapy with beta-lactam monotherapy or combination with an aminoglycoside or a quinolone for Pseudomonas aeruginosa bacteremia.
abstract: BACKGROUND
  Bacteremia by Pseudomonas aeruginosa represents one severe infection. It is not clear whether beta-lactam monotherapy leads to similar rates of treatment success compared to combinations of beta-lactams with aminoglycosides or quinolones.
  
  
  METHODS
  Retrospective cohort study from 3 tertiary hospitals (2 in Greece and 1 in Italy). Pseudomonas aeruginosa isolates were susceptible to a beta-lactam and an aminoglycoside or a quinolone. Patients received appropriate therapy for at least 48 hours. Primary outcome of interest was treatment success in patients with definitive beta-lactam combination therapy compared to monotherapy. Secondary outcomes were treatment success keeping the same empirical and definitive regimen, mortality, and toxicity.
  
  
  RESULTS
  Out of 92 bacteremias there were 54 evaluable episodes for the primary outcome (20 received monotherapy). Treatment success was higher with combination therapy (85%) compared to beta-lactam monotherapy (65%), however not statistically significantly [Odds ratio (OR) 3.1; 95% Confidence Interval (CI) 0.69-14.7, p = 0.1]. Very long (>2 months) hospitalisation before bacteremia was the only factor independently associated with treatment success (OR 0.73; 95% CI 0.01-0.95, p = 0.046), however this result entailed few episodes. All-cause mortality did not differ significantly between combination therapy [6/31 (19%)] and monotherapy [8/19 (42%)], p = 0.11. Only Charlson comorbidity index was associated with excess mortality (p = 0.03).
  
  
  CONCLUSIONS
  Our study, in accordance with previous ones, indicates that the choice between monotherapy and combination therapy may not affect treatment success significantly. However, our study does not have statistical power to identify small or moderate differences. A large randomized controlled trial evaluating this issue is justified.
authors: Alfa Institute of Biomedical Sciences, Athens, Greece.
authors: Ioannis A
authors: IA
authors: Bliziotis
authors: Nicola
authors: N
authors: Petrosillo
authors: Argyris
authors: A
authors: Michalopoulos
authors: George
authors: G
authors: Samonis
authors: Matthew E
authors: ME
authors: Falagas
mesh_terms: D000617:Aminoglycosides / Q000627:therapeutic use; D000900:Anti-Bacterial Agents / Q000008:administration & dosage* / Q000627:therapeutic use; D016470:Bacteremia / Q000188:drug therapy*; D015331:Cohort Studies; D004359:Drug Therapy, Combination; D006801:Humans; D011552:Pseudomonas Infections / Q000188:drug therapy*; D011550:Pseudomonas aeruginosa / Q000187:drug effects*; D015363:Quinolones / Q000627:therapeutic use; D012189:Retrospective Studies; D016896:Treatment Outcome; D047090:beta-Lactams / Q000627:therapeutic use
chemical_list: D000617:Aminoglycosides; D000900:Anti-Bacterial Agents; D015363:Quinolones; D047090:beta-Lactams