Effect of imipenem treatment versus imipenem surgical prophylaxis on the intestinal microflora

The impact of imipenem treatment versus imipenem surgical prophylaxis on the intestinal microflora was investigated in 40 patients. Ten patients received 0.5 g imipenem four times a day and ten patients 1.0 g imipenem four times a day for four to 11 days for treatment of different infections. The imipenem treatment was associated with minor to moderate changes in the intestinal flora. There was a decrease in the numbers of enterobacteria, anaerobic cocci and bacteroides during treatment, but afterwards the microflora was normalized in all patients. No new colonization with imipenem-resistant bacteria was seen. No concentrations of imipenem in faeces were observed. Twenty patients undergoing elective colorectal surgery participated in the imipenem surgical prophylaxis group. To ten patients, imipenem was given in a dose of 0.5 g at induction of anaesthesia followed by subsequent doses of 0.5 g at 6 h intervals for 48 h. The other ten patients received 1 g imipenem at 6 h intervals for 48 h. The aerobic bacteria - staphylococci, streptococci, enterococci and enterobacteria - were suppressed significantly during the prophylaxis period. Among the anaerobic bacteria, cocci, bifidobacteria, eubacteria, lactobacilli, clostridia, fusobacteria and bacteroides decreased markedly during the same period. The microflora was normalized after two weeks. The imipenem concentrations in the intestinal mucosa varied between 0.1-3.6 mg/kg for the dose of 0.5 g and 3.2-13.4 mg/kg for the dose of 1.0 g, and the concentrations in the faecal samples were between 0.1-5.0 mg/kg and 0.7-11.3 mg/kg respectively.