Topics in clinical pharmacology: imipenem, a new broad spectrum antibiotic

Comparison of imipenem versus cefuroxime plus tobramycin as empirical therapy for febrile granulocytopenic patients and efficacy of vancomycin and aztreonam in case of failure

143 aplastic episodes with fever in 91 haematological patients with granulocytopenia were treated empirically in a randomized prospective study using either imipenem (Imi) or a combination of tobramycin and cefuroxime (T/C). Response after 72 h was significantly better in patients receiving Imi (44/75 vs 27/68, p < 0.05). This was seen especially in patients with bacteriologically proven infections where the isolated staphylococci and streptococci were more susceptible to Imi. In both groups, patients who failed to respond to the initial antibiotic therapy were given vancomycin and aztreonam (V/A). The response rate after another 72 h, measured using the same criteria as after the first 72 h, did not differ statistically between the groups. One patient in each study group died from the bacterial infection, both from Gram-positive bacteraemia. Duration of fever was significantly shorter in the Imi group (4 days vs 7 days, p < 0.04). Serum peak and trough concentrations of the antibiotics were comparable. Both regimens were well tolerated. Our results show that monotherapy with imipenem is superior to the combination of tobramycin and cefuroxime during the first 72 h of therapy and can be safely administered to neutropenic patients with predominantly Gram-positive infections. A combination of vancomycin and aztreonam, given when initial imipenem treatment has failed, was effective in only a few patients. Adjuvant glycopeptide therapy from the outset in the treatment of febrile granulocytopenic patients did not seem worthwhile.

Updated evaluation of the activity of antibiotics in a burn centre

The results of microbiological tests performed in a burns unit between January 1989 and December 1990 have been analysed. Burn wound swabs and biopsies, blood cultures, central venous and urinary catheters, bronchial aspirates, pharyngeal swabs and faecal cultures for a total of 7950 examinations were considered. Staph. aureus was the most frequently isolated bacterium, followed by Staph. epidermidis, Pseud. aeruginosa and E. coli. The antibiograms have shown a low efficacy rate of cephalosporins, even of the latest generation, while with Gram-positive isolates the highest rates of activity were recorded by vancomycin and teicoplanin (100 per cent sensitivity). The situation seems better with Gram-negative organisms since they appear to be sensitive to a larger number of antimicrobial agents.