The morbidity and mortality from pseudomonas aeruginosa infections is high and empiric double-antibiotic coverage (DAC) is sometimes given; quality evidence for this practice is lacking.
Although there is little supporting data, the following reasons have been given for DAC:
DAC provides better empiric coverage through differing mechanisms of antibiotic action
DAC prevents the emergence of antibiotic resistance during therapy
The potential harm of antibiotic overuse cannot be ignored, however, and include adverse reaction, microbial resistance, risk of super-infection with other organisms (e.g., Clostridium difficile), and cost.
There may be a signal in the literature demonstrating a survival benefit when using DAC for patients with shock, hospital-associated pneumonia, or neutropenia. The IDSA guidelines, however, do not support DAC for neutropenia alone; only with neutropenia plus pneumonia or gram-negative bacteremia.
Bottom line: Little data supports the routine use of DAC in presumed pseudomonal infection. It may be considered in patients with shock, hospital-associated pneumonia, or neutropenia (+/- pneumonia), but consult your hospital’s antibiogram or ID consultant for local practices.
