Efficacy of monotherapy in the treatment of Pseudomonas ventilator-associated pneumonia in patients with trauma.

Background: Controversy persists regarding the optimal treatment regimen for Pseudomonas ventilator-associated pneumonia (VAP). Combination antibiotic therapy is used to broaden the spectrum of activity of empiric treatment and provide synergistic bacteriocidal activity. The relevance of such "synergy" is commonly supposed but poorly supported. The purpose of this study was to evaluate the efficacy of monotherapy in the treatment of Pseudomonas VAP as measured by microbiological resolution.

Methods: Patients admitted to the trauma intensive care unit during a 36-month period with gram-negative VAP diagnosed on initial bronchoalveolar lavage (BAL) (> or = 10(5) colony forming units [CFU]/mL) were evaluated. All patients received empiric antibiotic monotherapy based on the duration of intensive care unit stay. Patients with Pseudomonas VAP were identified and appropriate monotherapy was selected. Repeat BAL was performed on day 4 of appropriate antibiotic therapy to determine efficacy. Microbiological resolution was defined as < or = 10(3) CFU/mL. Combination therapy with an aminoglycoside was reserved for patients with either persistent positive or increasing colony counts on repeat BAL. Recurrence was defined as > or = 10(5) CFU/mL on subsequent BAL after 2 weeks of appropriate therapy.

Results: One hundred ninety-six patients were identified with late gram-negative VAP. There were 84 patients with Pseudomonas VAP. Monotherapy achieved microbiological resolution in 79 patients (94.1%) with zero recurrence. Thirty-six isolates were completely eradicated at repeat BAL. Five patients (5.9%) required combination therapy to achieve resolution.

Conclusions: Monotherapy in the treatment of Pseudomonas VAP has an excellent success rate in patients with trauma. Empiric monotherapy therapy should be modified once susceptibility of the microorganism is documented (all isolates were sensitive to cefepime) and antibiotic choice should be based on local patterns of susceptibilities. The routine use of combination therapy for synergy is unnecessary. Combination therapy should be reserved for patients with persistent microbiological evidence of Pseudomonas VAP despite adequate therapy.