Effect of ofloxacin on oral and gastrointestinal microflora in patients undergoing gastric surgery.

The effect of ofloxacin on the microflora in saliva, gastric juice, and feces was evaluated in 24 patients undergoing gastric surgery. A single peroral dose of 400 mg ofloxacin was given to each patient 2-4 h before surgery. The concentrations of ofloxacin in serum, saliva, gastric juice, and gastric mucosa tissue were assayed. Only Branhamella cocci were affected in the saliva. In the gastric juice, both the aerobic and anaerobic flora were suppressed on the day of surgery, but increased in number afterwards. There was a significant correlation between gastric pH and the number of microorganisms isolated in the gastric juice on day 0. In faeces, the aerobic and part of the anaerobic flora were suppressed by the administration of ofloxacin. Ofloxacin was well tolerated by the patients. Four of 24 patients developed postoperative complications. Microorganisms isolated from wound sepsis and intraabdominal sepsis (three patients) were Staphylococcus epidermidis, Staphylococcus aureus, hemolytic streptococci group A, Streptococcus sp. and Escherichia coli. All related infections occurred in patients with very low ofloxacin serum concentrations, probably due to impaired absorption. Oral antibiotic prophylaxis is not recommended in patients in whom impaired gastric emptying can be expected.