Bactericidal antimicrobial cover in primary suture of perianal or pilonidal abscess. A prospective, randomized, double-blind clinical trial.

The effect of 1-day treatment vs. 4-day treatment with metronidazole and ampicillin in association with primary closure of perianal and pilonidal abscesses was evaluated in a double-blind clinical trial. The patients were randomly allocated to 1-day (group I) or 4-day (group II) antibiotic regimen. No clinical signs of sepsis appeared in any patient. Primary healing, without fistula formation was achieved in all 17 perianal abscesses in the 1-day therapy group and in 14 of 15 in the 4-day group (non-significant difference). Excision with primary suture of pilonidal abscess resulted in primary healing in 20 of 26 cases in group I and 20 of 30 in group II (non-significant difference). Healing with formation of a new sinus or secondary healing occurred in four and two cases, respectively, in the 1-day therapy group, and in two and nine of the 4-day group. One-day administration of metronidazole/ampicillin is as effective as 4-day treatment in primary closure of perianal and pilonidal abscess. The procedure appears to be safe in both groups, but more efficacious in perianal abscess.