Purpose: This experimental study was designed to use the hydrogen (H2) breath test to investigate changes in the intestinal flora of patients that were administered prophylactic antibiotics for 48 hours after surgery.
Methods: Altogether, 22 patients were divided into two groups and the antimicrobial prophylactics, cefazolin (3.0 g/day) or sulbactam/ampicillin (4.5 g/day), were administered on induction of anaesthesia for 48 hours after surgery. End expiratory breath samples were collected on the morning of the day of surgery and every morning for 1-6 days after surgery.
Results: H2 breath concentration significantly decreased in each group on day 1 (cefazolin: 1.20 ± 0.39 ppm vs. sulbactam/ampicillin: 1.17 ± 0.34 ppm). On day 2, the H2 concentration in the sulbactam/ampicillin group was significantly lower than the cefazolin group (cefazolin: 6.4 ± 2.2 ppm vs. sulbactam/ampicillin: 1.0 ± 0.4 ppm, p < 0.05). H2 concentration was still lower in the sulbactam/ampicillin group (1.3 ± 0.3 ppm vs. 3.3 ± 1.0 ppm, p = 0.10) on day 3. On days 4-6, H2 concentration was essentially the same for both groups.
Discussion: Colonic anaerobes are thought to be a reservoir of resistant organisms and prolonged antimicrobial treatment is a major cause for the development of resistance. Surgical prophylaxis is basically recommended for use within 24 hours after surgery. The breath H2 concentration in both groups significantly decreased 24 hours after administration. These results suggest that both antibiotics influence the activity of colonic anaerobes and the duration of surgical antibiotic prophylaxis should be as short as possible.