Work

1094. Performance of Toxin Enzyme Immunoassays and PCR Cycle Threshold for Differentiating Clostridium difficile Infection From Colonization in Children With Diarrhea

Year: 2018

Type: article

Abstract: Background Clostridium difficile colonization is common in children. PCR does not distinguish infection (CDI) from colonization. Toxin enzyme immunoassay (EIA) and PCR cycle threshold (Ct) may predict CDI in PCR+ adults, but assay performance in children is poorly understood. Methods Stools from children aged 2–21 years with laboratory-identified (labID) CDI (tcdB PCR+; GeneXpert) underwent: toxin EIA (QUIK CHEK Complete [QCC] and Immunocard [IC]); cell culture cytotoxicity neutralization assay (CCCNA); and C. difficile stool culture (Cx). Children were determined to have clinical CDI (cCDI) by chart review and/or parent communication if all were noted: at least three unformed stools (Bristol type 5–7) in 24 hours; response to CDI treatment within 5 days; and no other likely diarrheal etiology. EIA and PCR Ct performance were measured for various reference standards (RefStd) based on stool assay results and/or cCDI classification. Results A total of 253 PCR+ stools were included. All stools underwent QCC; 218 (86%) were quantity sufficient for IC. Discordant EIA results occurred in 19/218 (8.7%) stools. Table 1 lists EIA sensitivity (Sn), EIA specificity (Sp), and median PCR Ct for each RefStd. Figure 1 shows the receiver operating characteristic (ROC) curve for PCR Ct to identify PCR+/CCCNA+/cCDI+ children (area under curve = 0.76). The difference between sensitivity (71%) and specificity (72%) was minimized at Ct < 23.5. Conclusion Only a minority of PCR+ children meets strict clinical and laboratory CDI criteria. More stringent CDI definitions are associated with increasing toxin EIA Sn and lower PCR Ct (i.e., greater stool C. difficile inoculum). However, both toxin EIA and PCR Ct perform suboptimally as stand-alone tests to distinguish CDI from colonization in PCR+ children. Disclosures L. Kociolek, Alere/Techlab: Investigator, Research support.

Source: Open Forum Infectious Diseases

DOI: 10.1093/ofid/ofy210.929

Authors: Aakash Balaji, Robyn Espinosa, Kathleen Todd, Kerry Steed, Larry Kociolek

Institutions: Northwestern University, Lurie Children's Hospital

Language: English

Topic: Clostridium difficile and Clostridium perfringens research

Subfield: Infectious Diseases

Field: Medicine

Domain: Health Sciences

SDG: Good health and well-being

Open Access status: gold

Estimated APC paid: $4,053