title: Association Between Appendectomy and Clostridium difficile Infection.
abstract: BACKGROUND
  Recent theory proposes that the appendix functions as a reservoir for commensal bacteria, and serves to re-inoculate the colon with normal flora in the event of pathogen exposure or purging of intestinal flora. If true, we reasoned that flora from a normal appendix could provide protection against Clostridium difficile. We conducted this investigation to examine the protective effect of an intact appendix and test the hypothesis that prior appendectomy will be more common among patients with a positive test for C. difficile as compared with patients who test negative.
  
  
  METHODS
  We contacted patients who had undergone C. difficile testing and asked them whether or not they had a prior appendectomy. Using their responses and results from Toxin A & B EIA tests, we calculated the difference in appendectomy rates between those who tested positive for C. difficile, and those who tested negative. We considered a positive 15% absolute difference to represent a significant increase in appendectomy rate.
  
  
  RESULTS
  We enrolled 257 patients. Among the 136 who tested positive for C. difficile, 27 (19.9%) had prior appendectomies, while among 121 patients testing negative for C. difficile, 38 (31.4%) had prior appendectomies, yielding a difference in appendectomy rates of -11.6% (95% Confidence Interval: -21.6% to -0.9%).
  
  
  CONCLUSIONS
  The rate of prior appendectomy was actually lower among patients with a positive C. difficile test as compared to those with a negative test. Conversely, patients who tested positive for C. difficile were more likely to have an intact appendix than those who tested negative. These results suggest that rather than being protective, an intact appendix appears to promote C. difficile acquisition, carriage, and disease.
  
  
  BACKGROUND
  Clostridium difficile; Appendix; Appendectomy; Microbial reservoir; Infection.
authors.affiliation: The UCLA Emergency Medicine Center, UCLA Geffen School of Medicine, Los Angeles, CA, USA.
authors.forename: Rashida
authors.initials: R
authors.lastname: Merchant
authors.forename: William R
authors.initials: WR
authors.lastname: Mower
authors.forename: Ariel
authors.initials: A
authors.lastname: Ourian
authors.forename: Fredrick M
authors.initials: FM
authors.lastname: Abrahamian
authors.forename: Gregory J
authors.initials: GJ
authors.lastname: Moran
authors.forename: Anusha
authors.initials: A
authors.lastname: Krishnadasan
authors.forename: David A
authors.initials: DA
authors.lastname: Talan