Metronidazole (M) has potent bactericidal activity against anaerobic bacteria. This study was designed to compare its efficacy and safety when combined with
gentamicin (M + G) to those of an accepted regimen,
clindamycin plus
gentamicin (C + G), for the treatment of
intra-abdominal infection. Patients were randomly allocated to receive 500 mg of M or 600 to 800 mg of
clindamycin (C) each combined with G, 1.5 mg/kg, all administered intravenously every 8 hours. Of 186 patients enrolled, 45 were excluded from analysis (22, M + G). Of the remaining 141 patients, 72 had been allocated to the M + G group. Data refer to M + G and C + G groups, respectively.
Infections included
abscess in 37 and 30 patients and
peritonitis in 30 and 31.
Appendicitis was the most common underlying disease, causing
intra-abdominal infection in 21 and 22 patients, with
diverticulitis occurring next most frequently, seven and 10 patients. Both anaerobic and aerobic bacteria were isolated from abdominal
pus in 32 and 27 patients, anaerobes alone in seven and four, and aerobes alone in 24 and 25. In six and seven patients,
pus was not cultured. Anaerobic
bacteremia occurred in 10/66 and 6/64 patients from whom blood was cultured. Patients were classified as cured, improved, or treatment failures. These ratios were 60:8:4 and 58:8:3. Median trough serum concentrations of M and C were 13.0 and 3.7 micrograms/ml, respectively, and at 15 minutes after infusion, 15 and 10.7 micrograms/ml, respectively. The frequencies of
rash,
diarrhea, and
superinfection were not different in the two treatment groups although abnormal serum tests of liver function occurred more commonly in the C+G group. M+G and C+G are not different in efficacy and acceptability for the
therapy of serious
intra-abdominal infections in adults.