Wound sepsis remains a common problem following surgery on the gastrointestinal tract. Infection of the incision site associated with appendectomy has been reduced but still approaches 7.2 percent. While many strategies aimed at minimizing the infection rate have been explored, most notably the use of oral or parenteral antibiotics, the results are less than satisfactory. Postoperative infection affects length of hospital stay and recovery time. Shubing and Litian investigated the impact of infusing metronidazole into the subcutaneous muscle and tissue around the incision site to reduce the incidence of wound infection following acute appendectomy.

Between 1991 and 1995, 260 patients who underwent acute appendectomy at a Mongolian hospital were evaluated for inclusion in the study. Twenty-one patients with diabetes, intestinal tuberculosis, tumor or a history of lengthy steroid treatment were excluded. The remaining 239 patients were randomized to a treatment group that received metronidazole injection at the incision site or to a control group that received intravenous metronidazole and cephazolin. After induction of anesthesia, patients in the treatment group received 60 to 80 mL of metronidazole solution (0.915 g metronidazole disodium phosphate or 25 percent metronidazole glucose solution in 100 mL of 0.9 percent normal saline solution) injected by layers. Patients in both groups received intravenous metronidazole and 4 g of cephazolin daily postoperatively. Patients were monitored for infection at the incision site for one month following surgery.

Patients were comparable in age, sex, type of surgery and average time from onset of symptoms until surgery. The severity of appendicitis was almost identical in the two groups of patients (see accompanying table). Infection developed in only one patient (0.8 percent) in the treatment group. In the control group, 14 patients (11.6 percent) had clinical wound infection. In addition, patients in the control group stayed in the hospital 10 days longer than those in the treatment group.

The authors conclude that preoperative local infiltration of metronidazole into the muscle tissue resulted in a significant reduction in the incidence of infection at the incision site following appendectomy for acute appendicitis. They attribute much of this effect to the direct exposure of anaerobic bacteria to an appropriate antimicrobial medication in areas of limited perfusion.