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Medline ® Abstract for Reference 77

of 'Clostridium difficile infection in adults: Clinical manifestations and diagnosis'

Fatal pseudomembranous colitis associated with a variant clostridium difficile strain not detected by toxin A immunoassay.
Johnson S, Kent SA, O'Leary KJ, Merrigan MM, Sambol SP, Peterson LR, Gerding DN
Ann Intern Med. 2001;135(6):434.
BACKGROUND: Many clinical laboratories use toxin A immunoassays to test for Clostridium difficile.
OBJECTIVE: To describe the clinical course of a patient infected with a toxin variant strain of C. difficile that was not detected by toxin A immunoassay; to genetically characterize this strain; and to estimate the number of laboratories that use only toxin A immunoassays.
DESIGN: Case report, molecular investigation, and laboratory survey.
SETTING: Tertiary care hospital in Chicago, Illinois.
PATIENT: An 86-year-old man.
MEASUREMENTS: Restriction endonuclease analysis, polymerase chain reaction, and survey of regional clinical laboratories.
RESULTS: An elderly hospitalized man died of advanced pseudomembranous colitis. Four stool specimens submitted over a 2-month period had tested negative on toxin A immunoassay, but a strain of C. difficile with a 1.8-kb deletion of the toxin A gene was recovered from each specimen. This strain, identified as restriction endonuclease analysis type CF4, is closely related to a widely disseminated variant, toxinotype VIII. Toxin A immunoassay was the only test being performed for detection of C. difficile at 31 of 67 (46%) regional clinical laboratories.
CONCLUSIONS: Toxin A variant strains of C. difficile cause serious disease and are undetectable in clinical laboratories that use only toxin A immunoassays for C. difficile testing.
Medical Service, Veterans Affairs Chicago Health Care System-Lakeside, 333 East Huron Street, Chicago, IL 60611, USA.