title: Association between antibody response to toxin A and protection against recurrent Clostridium difficile diarrhoea.
abstract: BACKGROUND
  We have reported that symptom-free carriers of Clostridium difficile have a systemic anamnestic immune response to toxin A. The aim of this study was to determine whether an acquired immune response to toxin A, during an episode of C. difficile diarrhoea, influences risk of recurrence.
  
  
  METHODS
  We prospectively studied 63 patients with nosocomial C. difficile diarrhoea. Serial serum IgA, IgG, and IgM concentrations against C. difficile toxin A, toxin B, or non-toxin antigens were measured by ELISA. Individuals were followed for 60 days.
  
  
  RESULTS
  19 patients died (30%). Of the 44 who survived, 22 had recurrent C. difficile diarrhoea. Patients with a single episode of C. difficile diarrhoea (n=22) had higher concentrations of serum IgM against toxin A on day 3 of their first episode of diarrhoea than those with recurrent diarrhoea (n=22, p=0.004). On day 12, serum IgG values against toxin A were higher in patients who had a single episode of diarrhoea (n=7) than in those who subsequently had recurrent diarrhoea (n=9, p=0.009). The odds ratio for recurrence associated with a low concentration of serum IgG against toxin A, measured 12 days after onset of C. difficile diarrhoea, was 48.0 (95% CI 3.5-663).
  
  
  CONCLUSIONS
  A serum antibody response to toxin A, during an initial episode of C. difficile diarrhoea, is associated with protection against recurrence.
authors.affiliation: Gerontology Division, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA. lkyne@caregroup.harvard.edu
authors.forename: L
authors.initials: L
authors.lastname: Kyne
authors.forename: M
authors.initials: M
authors.lastname: Warny
authors.forename: A
authors.initials: A
authors.lastname: Qamar
authors.forename: C P
authors.initials: CP
authors.lastname: Kelly
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000917:Antibody Formation; D001427:Bacterial Toxins / Q000276:immunology*; D016360:Clostridioides difficile / Q000276:immunology*; D004761:Enterocolitis, Pseudomembranous / Q000276:immunology*; D004768:Enterotoxins / Q000276:immunology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012008:Recurrence
chemical_list: D001427:Bacterial Toxins; D004768:Enterotoxins