Intra-operative culture swabs in acute appendicitis: A waste of resources

Abstract

Antibiotics gained a place in the management of acute appendicitis when the bacterial aetiology was demonstrated. Culture swabs were obtained routinely during appendicectomies to guide antibiotic use. Although current antimicrobial therapy use has become prophylactic, empirical and broad spectrum, this age-old practice still remains. Our study questions the value of this traditional practice. All adult and paediatric patients undergoing emergency appendicectomy over three years were retrospectively reviewed. Microbiology and appendix histology reports were retrieved. Occurrence of infective post-operative morbidity was recorded via hospital notes. A total of 652 appendectomies (age 1 month to 81 years, median 20 years) were performed in a 36 month period. Four hundred and thirty-five/six hundred and fifty-two (66.7%) had intra-operative swabs taken. One hundred and forty/four hundred and thirty-five (32%) revealed presence ofa pathogens. One hundred and twenty-two/four hundred and thirty-five (28%) were sensitive to broad spectrum empirical antibiotics and only 18/435 (4.1%) cultured resistant strains. Forty-two/six-hundred and fifty-two (6.4%) patients had postoperative infective complications. Twenty-nine/forty-two (68%) had a different organism responsible for this complication. The highest proportion of positive cultures and post-operative infective complications was observed in the extremes of ages (< 10 and > 50 years) and in gangrenous appendicitis. A majority of intra-operative swabs were negative or isolated commensal flora. Pathogens causing postoperative morbidity were frequently different from those isolated intra-operatively. None of the patients had a change of management based on the swab results. Hence routine intra-peritoneal swabs remains of little clinical value.