Addition of rifampin to carboxypenicillin-aminoglycoside combination for the treatment of Pseudomonas aeruginosa infection: clinical experience with four patients.

Four patients infected with Pseudomonas aeruginosa were treated with the triple therapy of carboxypenicillin (carbenicillin or ticarcillin), aminoglycoside (gentamicin or tobramycin), and rifampin. Two patients had P. aeruginosa endocarditis, one had bacteremia associated with granulocytopenia, and one had neurosurgical meningitis. In all four cases, the clinical condition of the patient deteriorated on combined antipseudomonal penicillin and aminoglycoside therapy. All patients had persistent blood cultures (throughout a 3- to 30-day period) or cerebrospinal fluid cultures (throughout a 24-day period) while receiving penicillin-aminoglycoside therapy. Rifampin, 600 mg every 8 h orally, was added to the penicillin-aminoglycoside regimen. All four patients defervesced within 24 h after the initiation of rifampin. In addition, all four patients experienced sterilization of blood and cerebrospinal fluid cultures within 24 h of therapy. The emergence of rifampin-resistant P. aeruginosa was not observed. Ultimately, two patients survived their infection; the other two patients succumbed to complications of their underlying disease. This clinical experience should provide a stimulus for a controlled evaluation of rifampin as a component of multiple drug therapy directed against P. aeruginosa.