Safety and efficacy of high-dose treatment with imipenem-cilastatin in seriously ill patients.

Imipenem-cilastatin was given in doses of 1 g intravenously every 6 h to 31 patients. Twenty-five patients, with 27 infections, were clinically evaluable and received 20 to 210 g of imipenem for a duration of 5 to 56 days (average 16.3 days). Infections included seven cases of osteomyelitis, seven of bacteremia, five of cellulitis, two of pneumonia, three of pelvic cellulitis, two of intraabdominal abscess, and one each of empyema, mediastinitis, and endometritis. Fifty-five percent of the infections were caused by gram-negative bacilli, 33% were due to gram-positive organisms, and 10% were caused by anaerobes. Twenty-two patients (81%) were cured, three improved, one relapsed, and one became superinfected with a resistant organism. In 5 of 11 cases with Pseudomonas aeruginosa, the imipenem MIC for organisms isolated by the end of treatment was higher than it was initially, raising concern that imipenem should not be used alone to treat Pseudomonas aeruginosa infections. Twenty-one patients had no adverse reaction; of the remaining 10 patients, 4 had nausea, 1 had urticaria, and 6 had mild abnormalities in hepatic function; three episodes of diarrhea included two with Clostridium difficile toxin in stool and one with pseudomembranous colitis, as determined by sigmoidoscopy. Levels of creatinine, hemoglobin, leukocytes, platelets, prothrombin, and urine components were unchanged. Imipenem-cilastatin is a clinically effective antibiotic with freedom from nephrotoxicity and hematological abnormalities in the large doses used in this study.