353. Clostridium difficile Anti-toxin A Antibody in Healthcare Workers
Session: Poster Abstract Session: Clostridium difficile - Epidemiology, Diagnosis, Treatment, and Prevention
Friday, October 21, 2011
Room: Poster Hall B1


Clostridium difficile (CD) is the most common cause of infectious diarrhea in hospitalized patients and is associated with significant morbidity and mortality.  Healthcare workers (HCW) are frequently exposed to the organism but published reports of symptomatic CD infections are rare in this population.  Low titers of anti-toxin A antibody in hospitalized patients with CD in stool have been associated with infection.  Little is known about anti-toxin antibodies in HCWs or how they compare to non-HCWs. The goal of this study was to develop an enzyme immunoassay (EIA) to measure antitoxin A antibodies, and to compare titers among HCWs and age and gender matched controls.


Eighty-five HCWs who provide direct patient care volunteered to complete a questionnaire and provide a blood sample.  Eighty-five age and gender matched outpatient blood samples were randomly obtained from the laboratory to serve as controls. Ninety-six well plates were coated with CD toxin A at 0.5 mcg/mL or PBS/BSA alone.  Samples were diluted 1:1000 and processed in triplicate in antigen and non-antigen wells.  Nonspecific background was corrected by subtracting wells without antigen from those wells with antigen. Results were averaged and reported as an optical density (OD).  The study was powered to detect a 50% difference in OD. The anti-toxin A antibodies were compared with the Wilcoxon signed-rank matched-pairs test.


The median age of subjects was 38 years, and 73% were female. HCWs had significantly higher antibody titers than controls (p < .01) when analyzed as non-parametric matched pairs or as means. Among HCWs, age, gender, and years in healthcare were not associated with antibody response.


HCWs providing direct patient care in an academic medical center were found to have significantly higher CD anti-toxin A antibody titers than age and gender matched controls. It is not known if the antibody levels measured confer protection against CD infection or can account for the anecdotally low incidence of CD diarrhea among HCWs despite frequent exposure to the organism.  Further research could compare HCW antibody titers to those convalescing from CD infection.


Subject Category: N. Hospital-acquired and surgical infections, infection control, and health outcomes including general public health and health services research

Cindy Noyes, MD, Infectious Disease, Fletcher Allen Health Care/University of Vermont, Burlington, VT, Christopher Huston, MD, Univ of Vermont College of Medicine, Burlington, VT and Wallace Alston, MD, MPH, Fletcher Allen Health Care, Burlington, VT


C. Noyes, None

C. Huston, None

W. Alston, None

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