Impact of the Type of Diagnostic Assay on Clostridium difficile Infection and Complication Rates in a Mandatory Reporting Program Yves Longtin, Sylvie Trottier, Gilles Brochu, Bianka Paquet-Bolduc, Christophe Garenc, Vilayvong Loungnarath, Catherine Beaulieu, Danielle Goulet, and Jean Longtin Clinical Infectious Diseases 2013;56(1):67–73 R2 김다래 / PROF. 박기호

INTRODUCTION Clostridium difficile a species of Gram-positive spore-forming bacterium that is best known for causing antibiotic-associated diarrhea Clostridium difficile infection (CDI) growing problem in inpatient healthcare facilities causes significant morbidity and mortality increasing incidence and severity due to the emergence of hypervirulent strains

INTRODUCTION To better understand its epidemiology, detect outbreaks, and improve its control, the surveillance and reporting of CDI rates have been implemented in numerous jurisdictions. Despite this attempt to formalize methodology, no clear guidance has been emitted regarding the type of laboratory test to diagnose CDI on stool samples. Various laboratory tests can be used to diagnose CDI, and institutions have a wide range of options. However, these methods differ in terms of sensitivity, specificity, cost, and turnaround time, and considerable debate persists regarding the optimal method of detection. 그렇기 때문에 질병에 대한 자세한 이해를 위해, Clostiridium difficile infection rate에 대한 surveillance 및 reporting이 다양한 방면에서 이루어지고 있습니다. 하지만 그럼에도 불구하고, CDI를 진단하는데 있어서 사용되는 여러 진단학적 검사에 대한 명확한 guidance가 없는 실정입니다. 사실 CDI를 진단하는데 사용되는 다양한 진단한적 검사들은 각각의 sensitivity, specificity, turnaroudn time에 따라 결과의 차이를 보이기 때문에 CDI detection에 가장 적합한 방법이 무엇인지 논란이 있습니다.

INTRODUCTION 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 rates and complication rates obtained by 2 validated diagnostic methods.

METHODS Study Design and Setting prospective observational cohort study Quebec University Institute of Cardiology and Pneumology (IUCPQ), Quebec City, Canada 1 August 2010 - 31 July 2011 to compare incidence rates, complication rates of healthcare-associated CDI (HA-CDI) obtained using 2 different diagnostic strategies(PCR and EIA/CCA).

METHODS Definitions CDI (Clostridium difficile Infection ) (1) diarrhea without other known etiology combined with a positive test result for toxin-producing C. difficile (≥3 loose or liquid stools in <24 hours and symptoms lasting ≥24 hours) (2) a clinical diagnosis based on histopathology or direct visualization of pseudomembranes by colonoscopy HA-CDI (Hospital acquired Clostridium difficile Infection ) Symptoms ≥72 hrs after admission and up to 4 weeks following discharge. CA-CDI (Community acquired Clostridium difficile Infection) symptoms <72 hrs of admission and who had not been hospitalized in the previous 4 weeks

METHODS Laboratory Diagnostic Algorithms : 2 different diagnostic algorithms for C. difficile 1-step approach based on PCR targeting the ToxB gene tcdB 3-step algorithm subsequently referred to as EIA/CCA 1-step PCR Figure 1. Flowchart of laboratory diagnosis of Clostridium difficile in stool samples by PCR and by the 3-step algorithm EIA/CCA 3-step EIA/CCA

RESULTS PCR: 224/1321 EIA/CCA: 162/1321

RESULTS Table 1. Summary of Clostridium difficile Infection and Incidence Rates Detected by PCR and by EIA/CCA Algorithm, University Institute of Cardiology and Pneumology, Quebec, Canada, August 2010–July 2011

RESULTS 18.7 16.1 2.9 0.0 Figure 2. Incidence of healthcare-associated Clostridium difficile infection (CDI) according to standardized surveillance definitions, August 2010–July 2011, Quebec University Heart and Lung Institute, Quebec City, Canada. PCR and EIA/CCA were used for detection of CDI.

RESULTS Table 2. Frequency of Complications ass with CDI as Detected by PCR Only and by Both PCR and EIA/CCA Algorithm, University Institute of Cardiology and Pneumology, Quebec, Canada, August 2010–July 2011

CONCLUSION Incidence rates and Complication rates influenced by type of laboratory test used to diagnose CDI and that cases detected by PCR, but not by EIA/CCA 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 interhospital comparison