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Background. Most Clostridium difficile infection (CDI) surveillance programs neither specify the diagnostic method to be used nor stratify rates accordingly. We assessed the difference in healthcare-associated CDI (HA-CDI) incidence and complication rates obtained by two validated diagnostic methods.Methods. Prospective cohort study of patients for whom a C. difficile test was ordered between 1 August 2010 and 31 July 2011. All specimens were tested in parallel by a commercial polymerase chain reaction (PCR) assay targeting toxin B gene tcdB, and a three-step algorithm detecting glutamate deshydrogenase and toxins A and B by enzyme immunoassay and cell culture cytotoxicity assay (EIA/CCA). CDI incidence rate ratios were calculated using univariate Poisson regression.Results. 1321 stool samples were tested during a period totalling 95,750 patient-days. 85 HA-CDI cases were detected by PCR and 56 cases by EIA/CCA (P=0.01). The overall incidence rate was 8.9 per 10,000 patient-days (95% CI, 7.1-10.9) by PCR and 5.8 per 10,000 patient-days (95% CI, 4.4-7.4) by EIA/CCA (P=0.01). The incidence rate ratio comparing PCR and EIA/CCA was 1.52 (95% CI, 1.08-2.13; P=0.015). Overall complication rate was 27% (23/85) when CDI was diagnosed by PCR and 39% (22/56) by EIA/CCA (P=0.16). Cases detected by PCR only were less likely to develop a complication of CDI compared with cases detected by both PCR and EIA/CCA (3% vs. 39%, respectively; P<0.001).Conclusion. Performing PCR instead of EIA/CCA is associated with a >50% increase in the CDI incidence rate. Standardization of diagnostic methods may be indicated to improve inter-hospital comparison. |
发表于 2013-4-16 16:26
发表于 2013-4-16 18:20