Bacterial flora of the appendix fossa in appendicitis and postoperative wound infection

Bacteria were isolated from 153 (47.5%) swabs of the appendix fossa in 322 patients undergoing appendicectomy. The commonest organism was Bacteroides species found in 78% of specimens. Other Gram-negative bacilli such as Klebsiella, or Enterobacter, and Esch. coli were present in 29 and 27% respectively. Gram-positive cocci were less frequently isolated.A positive culture was obtained more commonly in perforated appendicitis (79%) than where chronic fibrosis, lymphoid hyperplasia, or acute appendicitis was present or when the appendix was normal. Bacteroides was isolated twice as often in perforated appendicitis. The incidence of wound infection was 19% and varied according to the state of the appendix, being 63% in perforated appendicitis and 9.5% where lymphoid hyperplasia was present. Bacteroides was isolated from over 90% of the wound infections. In the patients with perforated appendicitis where effective chemotherapy was given the incidence of wound infection was 15% whereas in untreated or inappropriately treated patients it was over 50%. The isolation of bacteroides requires special precautions to be taken both in the collection of the specimen and laboratory culture. It is important that the chemotherapy of postappendicectomy infections include an antibiotic active against bacteroides.

Aetiology and prevention of wound infection in appendicetomy

A study at the Reading District Hospitals on 451 consecutive patients undergoing appendicectomy through grid-iron incisions sought to determine factors influencing wound infection and the effects of a prophylactic wound-spraying procedure. Wound infection increased with the severity of appendicular inflammation and was well correlated with the degree and nature of bacterial contamination at the time of wound closure.

The infection rate was reduced by about one-half when either an aerosol dry-powder formulation of povidone iodine (Disadine D. P.) or an aerosol antibiotic powder spray containing neomycin, bacitracin and polymixin (Dispray) was sprayed on the wound before and after closure. The reduction of infection achieved by spraying with pouidine iodine was statistically significant (P < 0.025). The results of the polyantibiotic spraying did not quite reach significance (P < 0.06).

The povidone iodine dry powder was better overall since it reduced infection in all degrees of appendicular inflammation, in all age groups and in enlarged, drained, contaminated and non-contaminated wounds without the attendant disadvantages of antibiotics.

The prevention of infection in appendicectomy wounds

Fifty cases of acute appendicitis were examined at operation for the presence of free organisms on or around the appendix in situ, and for bacterial contamination of the wounds after removal of the appendix. Fifty-four per cent had free organisms around the appendix, 40 per cent of the wounds probably became contaminated, and 18 per cent became clinically infected.

The operative technique was modified in 50 cases to minimize the chance of contaminating the wounds. There were 2 infections (4 per cent). In another series in which the usual operative technique was used the wounds were irrigated with tetracycline solution; there was 1 infection in 50 cases, an incidence of 2 per cent. In a similar trial the use of a mixture of powdered antibiotics in 50 cases did not influence the wound infection rate which remained at 18 per cent.

The use of tetracycline solution and care in avoiding contamination of the wound are recommended.