Clostridium Difficile Infection in Patients with Acute Myeloid Leukemia
Authors: Morris Amy L , Naeem Mohammed Athar , Bal Anjali , Thomas Tanya , Alshaibani Alfadel , Horton Bethany , Keng Michael K. 
Published: October 2019

Abstract
BACKGROUND: Clostridium difficile infection (CDI) is the most important cause of nosocomial infectious diarrhea and has been not well studied in patients with neutropenia who have hematologic malignancies in the United States. Previous studies suggest patients undergoing induction chemotherapy for acute myeloid leukemia (AML) are at a high risk of contracting CDI, but these patient's clinical and disease characteristics are not described. This study reports CDI rates and disease characteristics in AML patients at the University of Virginia (UVA).
METHODS: A retrospective chart review of 126 consecutive patients undergoing induction or re-induction chemotherapy for AML at UVA from July 2011 to December 2015 was conducted. The primary endpoint was to determine the rate of CDI within ninety days of chemotherapy initiation. CDI was defined by a Clostridium difficile positive PCR in the presence of diarrhea. Secondary endpoints include patient characteristics, comorbidities, risk factors, and disease specific indices associated with CDI. Statistical methods include nonparametric Wilcoxon test, Fisher's exact test, and Holm's sequential Bonferroni procedure as appropriate. Statistical significance was defined as p-value <0.05.
RESULTS: Of 126 patients, 31 patients (24.6%) with AML had CDI. 8 patients (25.8%) had one recurrent episode of CDI, 2 patients (6.4%) had two recurrences, and 2 patients (6.4%) had more than two recurrences. 25 patients (80.6%) underwent CT abdominal imaging specifically for the CDI episode, revealing 2 patients (8%) with typhilitis. 2 patients (6.4%) developed toxic megacolon, but no patients underwent colectomy. There was no CDI specific mortality in these 31 patients. During the same 4 year timespan, an additional 27 patients with hematologic malignancies other than AML were identified. These two cohorts (AML and non-AML CDI patients) were not statistically different in terms of patient demographics (age, gender, BMI), medical comorbidities (tobacco use, asthma, COPD, cardiac disorders, CKD, and rheumatologic conditions), and CDI characteristics (recurrences, prior antibiotics prophylactic and treatment regimens, PPI medication usage, CDI treatment regimen and treatment duration, development of typhilitis and toxic megacolon, and mortality). The only statistically significant difference is the presence and increased duration of neutropenia in the AML CDI patient cohort (p-value < 0.001).
DISCUSSION: The study concludes that the incidence of CDI in patients with AML undergoing induction chemotherapy is greater than hospitalized patients without AML as reported in the literature. However, when compared to a matched cohort of hospitalized patients with non-AML hematologic malignancies, the incidence of CDI is similar between these two groups. This result is striking as AML induction chemotherapy regimens are typically more intense, resulting in more profound and longer neutropenia. Even with increased cytopenias, the CDI rate and disease characteristics are not affected when AML CDI patients are compared to non-AML CDI patients. This suggests that cytopenias should not be the focus for CDI patients, rather hematologic malignancies as whole lead to increased CDIs and heightened awareness is warranted when caring for patients with hematologic malignancies and complaints of diarrhea. Patients in both AML and non-AML CDI cohorts have relatively favorable outcome, with no patient mortality attributable to CDI. Further studies are needed to evaluate what, if any, predictive risk factors can increase CDI in the setting of AML.

Disclosures
No relevant conflicts of interest to declare.