infection control & hospital epidemiology july 2018, vol. 39, no. 7 concise communication


Clinical Characteristics and Outcomes of Hematologic Malignancy Patients With Positive Clostridium difficile Toxin Immunoassay Versus Polymerase Chain Reaction Test Results


Matthew Ziegler, MD;1 Daniel Landsburg, MD;2 DavidPegues,MD;1,3 KevinAlby, PhD;4 Cheryl Gilmar, MS,MT;3 Kristen Bink,MSN, RN;2 Theresa Gorman, MSN, RN;2 AmyMoore, MSN, RN;2 Brittaney Bonhomme, BA;5 Jacqueline Omorogbe, BS;5 Dana Tango, MPH;5 Pam Tolomeo,MPH;5 Jennifer H. Han, MD,MSCE1,3,5


In a cohort of inpatients with hematologic malignancy and positive enzyme immunoassay (EIA) or polymerase chain reaction (PCR) Clostridium difficile tests, we found that clinical characteristics and outcomes were similar between these groups. The method of testing is unlikely to predict infection in this population, and PCR-positive results should be treated with concern.


Infect Control Hosp Epidemiol 2018;39:863–866


2015, to March 31, 2017. Patients with active hematologic malignancy and a positive C. difficile test during hospitalization were included. Stool samples ordered for C. difficile testing were processed


by the HUP Clinical Microbiology Laboratory. The testing algorithm uses a commercial EIA for detection of toxin A, B, and glutamate dehydrogenase (GDH) (C Diff Quik Check Complete, Alere, Waltham, MA). Samples that are negative for toxin A and B but positive for GDH are subsequently tested using PCR for toxin genes (BD MAX Cdiff Assay, Becton Dickinson, Franklin Lakes, NJ). Clinical data were collected using medical record review,


Both infection and colonization with Clostridium difficile are common in patients with hematologic malignancy; 10%–29% of patients are positive by culture on admission.1,2 However, while there is increasing recognition that molecular-based polymerase chain reaction (PCR) testing for C. difficile toxin lacks specificity for detecting infection as opposed to colonization,3,4 determining true infection in patients with hematologic malignancy may be particularly difficult given the high prevalence of diarrhea due to other etiologies (eg, chemotherapy or antibiotics)5,6 and the absence of typical signs and symptoms of infection such as leukocytosis or fever due to the effect of disease and/or therapy. Similarly, while studies have suggested lower rates of both characteristics pre- dictive of infection and poor outcomes in patients with PCR versus enzyme immunoassay (EIA) positive tests,7,8 it is unknown whether these findings apply to patients with hematologic malignancy. Therefore, we aimed to compare clinical characteristics and outcomes between patients with EIA- versus PCR-positive C. difficile test results in a cohort of inpatients with hematologic malignancy.


methods


We performed a retrospective cohort study of patients admitted to the Hospital of the University of Pennsylvania (HUP), a 776-bed tertiary-care medical center from January 1,


including demographics, comorbidities, antibiotic use in the previous month, clinical signs and symptoms (including fever, diarrhea, number of bowel movements, abdominal pain, and imaging evidence of colitis), and medication use in the 72 hours prior to the positive test. Clinical outcomes were also collected, including toxic megacolon, colectomy, recurrent C. difficile disease in the 90 days after index testing, as well as all-cause intensive care unit (ICU) transfer, in-hospital mortality, and hospital readmission. Clinical characteristics and outcomes of patients with EIA- versus PCR-positive C. difficile test results were compared using the χ2 or the Fischer exact test for categorical variables and the Wilcoxon rank-sum test for continuous variables using Stata version 14.2 software (StataCorp, College Station, TX). For all calculations, a 2-tailed P value <.05 was considered significant.


results


Over the 27-month study period in the hospital’s dedicated hematology oncology units, 11.6% of C. difficile tests were positive. Of the 182 patients admitted with hematologic malignancy who had a positive C. difficile test result, 101 patients (55%) had a PCR(+ )/EIA(−) result, and 81 patients (45%) had an EIA(+) result. Among patients without neutropenia, leukocytosis (white blood cell count >15,000 cells/mm3) at the time of testing was significantly more com- mon in the EIA(+ ) group (ie, 26%) versus the PCR(+)/EIA (−) group (ie, 11%; P=.02) (Table 1). There was no differ- ence in rates of severe CDI,9 fever, diarrhea, or imaging evidence of colitis between the 2 groups. Stool output trended towards being higher in the PCR(+)/EIA(−) group, with a median of 4 bowel movements per 24 hours compared to a median of 3 bowel movements per 24 hours in the EIA(+) group (P=.15). Receipt of medications associated with an increased risk for


CDI, including acid suppressants (52%) and systemic anti- biotics (80%), were similar in both groups. There were rela- tively high rates of recent use of laxatives (30%), but this was not significantly different between the 2 groups.


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