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

One-dose antibiotic prophylaxis against wound infection after appendicectomy: a randomized trial of clindamycin, cefazolin sodium and a placebo

Two hundred and fifty patients were admitted to a prospective randomized trial of single dosage prophylaxis against wound infection after appendicectomy. There were 12 exclusions, 72 patients received placebo, 81 received 600 mg i.m. clindamycin phosphate and 85 received 1 1 g i.m. cefazolin sodium, the agent being given in the anaesthetic room. Clindamycin produced a significant reduction in the overall rate of wound infection from 33 per cent in the controls to 17 per cent. In cases with a gangrenous or perforated appendix the infection rate in controls was 78 per cent; this was reduced to 44 per cent by a single dose of clindamycin. Cefazolin significantly reduced the number of aerobic organisms isolated from wound infections, but did not significantly reduce the incidence of wound infection. We conclude that anaerobic organisms are more important than faecal aerobic organisms in the pathogenesis of wound infection after appendicectomy.

Anaerobic organisms in postoperative wounds

A survey of the bacteria found in postoperative wounds was undertaken during a 14-month period. The yields of aerobic and anaerobic bacteria in 65 appendicectomy wounds were compared; 42 wounds yielded aerobes and 51 anaerobes. Seventy-eight other operation wounds yielded anaerobes, and, overall, 33 wounds yielded anaerobes only. Bacteroides sp were the most common anaerobic organisms isolated from all operation sites except the lung.

Should you drain a perforated appendix?

One hundred and three consecutive patients undergoing appendicectomy for perforated appendicitis were randomly allocated either to have an intraperitoneal drain inserted or not. The results of this trial lend no support to the advocates of drainage.

Wound infection following appendicectomy: the effect of extraperitoneal wound drainage and systemic antibiotic prophylaxis

The value of extraperitoneal wound drainage and a 3-day course of prophylactic systemic cephaloridine used both separately and together have been assessed in a prospective controlled randomized trial involving 246 patients undergoing appendicectomy at the Leicester Royal Infirmary. Extraperitoneal wound drainage was shown to reduce significantly the incidence of postoperative wound infection in patients with a gangrenous or perforated appendix (P less than 0-025). Prophylactic cephaloridine significantly reduced the overall incidence of wound infection (P less than 0-02) and was also effective when the appendix was gangrenous or perforated (P less than 0-01). A highly significant reduction in wound infection was achieved when the appendix was gangrenous or perforated by the addition of wound drainage to the antibiotic regimen (P less than 0-001).

Metronidazole in prevention and treatment of bacteroides infections in elective colonic surgery

A double-blind randomised trial was carried out among 46 patients undergoing elective colonic surgery; 27 patients received prophylactic metronidazole and 19 received placebo. Anaerobic infections did not develop in any of the metronidazole-treated patients, but did develop in 11 (58%) of 19 controls who were subsequently successfully treated with metronidazole.

Prophylactic lincomycin in the prevention of wound infection following appendicectomy: a double blind study

The prophylactic use of a single dose of lincomycin in 100 patients undergoing appendicectomy reduced the incidence of postoperative wound infection from 17 to 6 per cent compared with a similar group of control patients. There was no correlation with the histological finding in the appendix, but patients with perforated appendicitis were excluded from the study. Bacteriological examination of the appendix area before surgery showed that Bacteroides fragilis and Escherichia coli were the organisms most frequently isolated. The majority of wound infections were due to B. fragilis, either alone or in association with aerobic organisms, but infection due to E. coli and Staphylococcus aureus also occurred. Systemic antibiotic therapy can successfully reduce the complications following appendicectomy but it is necessary to use a compound with activity against anaerobic organisms.

Activity of cephazolin and other cephalosporins against Bacteroides fragilis

The antibiotic sensitivity of 50 strains of Bacteroides fragilis to four cephalosporin compounds, cephazolin, cephaloridine, cephradine and cephalexin is reported. Cephazolin was found to be the most active, 94 per cent of strains being susceptible to blood concentrations achieved on standard dosage, comparative findings with cephaloridine and cephradine were about 50 per cent, and only 22 per cent of strains were inhibited by cephalexin. The importance of infections due to bacteroides is discussed. Although not the treatment of choice, cephazolin, a view of its bacterial activity may be useful alternative for bacteroides infections but clinical trials are needed to confirm the laboratory results.

Bacteroides: an unusual cause of breast abscess

Three cases of breast abscess from which the non-sporing anaerobe Bacteroides was isolated are described. This organism has apparently not previously been reported as a cause of abscess in a breast without underlying malignancy.

Prophylaxis against anaerobic sepsis in bowel surgery

Sixty-two patients were admitted to a prospective randomized controlled trial to investigate the influence of a prophylactic antibiotic, lincomycin, on anaerobic sepsis following bowel surgery. The incidence of postoperative sepsis was reduced from 45 to 18 per cent (P less than 0-025). Wound infections were reduced from 38 to 12 percent (P less than 0-05). Intra-abdominal or pelvic abscess occurred in 1 of the treated group compared with 3 controls. Septicaemia occurred after operation in 1 patient receiving lincomycin and in 3 of the controls; in 2 of the latter, pure growths of bacteroides were isolated from the blood cultures and 1 of these patients died. Although lincomycin had no influence on the number of patients who developed aerobic postoperative infections, there was a significant reduction in the incidence of sepsis due to bacteroides, which occurred in 10 of the control group compared with 1 in the lincomycin group (P less than 0-005). No patients developed complications attributable to lincomycin, such as pseudomembranous colitis. These data indicate that the genus Bacteroides are important pathogenic organisms and are responsible for postoperative morbidity. Furthermore, anaerobic sepsis can be reduced by appropriate prophylactic antibiotics.

Metronidazole in prevention and treatment of bacteroides infections after appendicectomy

The frequency of non-clostridial anaerobic infection was studied in 95 patients who had undergone acute appendicectomy: 49 received prophylactic metronidazole and 46 received placebo. Anaerobic infection did not develop in any of the metronidazole-treated patients, but infections did develop in nine (19%) of the 46 controls. Metronidazole is conveniently administered by suppository to patients who cannot take oral drugs. Five patients with intra-abdominal infections caused by non-clostridial anaerobes were successfully treated with metronidazole.

Prophylactic interparietal povidone-iodine in abdominal surgery

This study sought to determine in a district general hospital (a) the frequency and nature of bacterial contamination at operation, (b) the incidence of consequent infection and (c) the prophylactic effect, if any, of interparietal povidone-iodine against postoperative wound infection. Bacterial contamination was shown in 49 per cent of all the abdominal surgical wounds at the end of operation. From 61 per cent of the subsequently infected wounds, organisms identified as contaminants at operation were again found. Interparietal instillation of povidone-iodine resulted in a statistically significant reduction in wound infection (P less than 0.01) in treated patients compared with untreated, randomized, matched controls. It was of significant value in cases of intestinal resection and peritonitis, in obese patients and in those with paramedian incisions. Laboratory studies indicate that povidone-iodine does not induce bacterial resistance. This chemical antibacterial agent may thus provide a preferable alternative to antibiotics in preventing such infections.

Wound infections due to Bacteroides fragilis following intestinal surgery

Ninety-six wound infections due to Bacteroides fragilis occurring after intestinal surgery are described. Most infections followed appendicectomy or colectomy for diverticulitis. B. fragilis was isolated in pure growth from 47 per cent of infections, and in mixed culture the other common bacteria were Klebsiella spp., Escherichia coli and Enterobacter spp. Fifty-three per cent of the infections responded rapidly to either non-specific measures or antibiotic therapy, but 47 per cent of patients developed complications, usually abscess formation. The successful isolation of bacteroides from clinical material requires special precautions. The specimen for bacteriological examination must be sent to the laboratory in a transport medium which maintains an anaerobic environment and the culture techniques must include a selective agar for the isolation of anaerobic bacteria. The role of antibiotic therapy in preventing postoperative wound infection after intestinal surgery is discussed. Bacteroides has an unusualy pattern of antibiotic susceptibility and it is essential that an effective antibiotic such as lincomycin is included in the treatment of infection originating from the intestinal tract.