Three different patterns of positive Clostridium difficile laboratory tests. A comparison of clinical behavior

Abstract Background Clostridium difficile (CD) diagnosis are very varied and under discussion. Different research groups disagree on the clinical significance of patients with negative direct toxin and positive PCR or even more with direct toxin and GDH both negatives, but CD detected by toxigenic culture (TC). Objective Analyze the characteristics of patients with three different diagnostic criteria. Methods We compared these three groups of patients: group 1:(GDH+/direct toxin+/PCR+), group 2:(GDH+/direct toxin-/PCR+) and group 3:(GDH-/direct toxin-/PCR not done/TC+). Results The proportion of patients with CD infection (CDI) (not colonization) for groups 1 to 3 were, respectively, 90.3%, 95.4% and 59.1%. No differences between severity (40.8%-38.5%-27.3%), recurrence (20.3%-24.1%-7.6%) or related mortality (12.5%-5.2%-0%) were found within the three groups of patients. Conclusions Laboratory clinical results should not be used as the only tool to differentiate CDI versus colonization or severity. We recommend that PCR or a second look TC be performed on all patients.