<p><strong>OBJECTIVES: </strong>To determine the frequency of false-positive Clostridium difficile toxin enzyme immunoassay (EIA) results in hospitalized children and to examine potential reasons for this false positivity.</p>

<p><strong>DESIGN: </strong>Nested case-control.</p>

<p><strong>SETTING: </strong>Two tertiary care pediatric hospitals.</p>

<p><strong>METHODS: </strong>As part of a natural history study, prospectively collected EIA-positive stools were cultured for toxigenic C. difficile, and characteristics of children with false-positive and true-positive EIA results were compared. EIA-positive/culture-negative samples were recultured after dilution and enrichment steps, were evaluated for presence of the tcdB gene by polymerase chain reaction (PCR), and were further cultured for Clostridium sordellii, a cause of false-positive EIA toxin assays.</p>

<p><strong>RESULTS: </strong>Of 112 EIA-positive stools cultured, 72 grew toxigenic C. difficile and 40 did not, indicating a positive predictive value of 64% in this population. The estimated prevalence of C. difficile infection (CDI) in the study sites among children tested for this pathogen was 5%-7%. Children with false-positive EIA results were significantly younger than those with true-positive tests but did not differ in other characteristics. No false-positive specimens yielded C. difficile when cultured after enrichment or serial dilution, 1 specimen was positive for tcdB by PCR, and none grew C. sordellii.</p>

<p><strong>CONCLUSIONS: </strong>Approximately one-third of EIA tests used to evaluate pediatric inpatients for CDI were falsely positive. This finding was likely due to the low prevalence of CDI in pediatric hospitals, which diminishes the test's positive predictive value. These data raise concerns about the use of EIA assays to diagnosis CDI in children.</p>

<p><strong>BACKGROUND: </strong>The incidence and severity of Clostridium difficile infection (CDI) is increasing among adults; however, little is known about the epidemiology of CDI among children.</p>

<p><strong>METHODS: </strong>We conducted a nested case-control study to identify the risk factors for and a prospective cohort study to determine the outcomes associated with severe CDI at 2 children's hospitals. Severe CDI was defined as CDI and at least 1 complication or ≥2 laboratory or clinical indicators consistent with severe disease. Studied outcomes included relapse, treatment failure, and CDI-related complications. Isolates were tested to determine North American pulsed-field gel electrophoresis type 1 lineage.</p>

<p><strong>RESULTS: </strong>We analyzed 82 patients with CDI, of whom 48 had severe disease. Median age in years was 5.93 (1.78-12.16) and 1.83 (0.67-8.1) in subjects with severe and nonsevere CDI, respectively (P = 0.012). All patients with malignancy and CDI had severe disease. Nine subjects (11%) had North American pulsed-field gel electrophoresis type 1 isolates. Risk factors for severe disease included age (adjusted odds ratio [95% confidence interval]: 1.12 [1.02, 1.24]) and receipt of 3 antibiotic classes in the 30 days before infection (3.95 [1.19, 13.11]). If infants less than 1 year of age were excluded, only receipt of 3 antibiotic classes remained significantly associated with severe disease. Neither the rate of relapse nor treatment failure differed significantly between patients with severe and nonsevere CDI. There was 1 death.</p>

<p><strong>CONCLUSIONS: </strong>Increasing age and exposure to multiple antibiotic classes were risk factors for severe CDI. Although most patients studied had severe disease, complications were infrequent. Relapse rates were similar to those reported in adults.</p>

<p><strong>OBJECTIVES: </strong>To study the trend of Clostridium difficile infection (CDI) and risk factors for hospital acquired CDI (HA-CDI) among children with cancer.</p>

<p><strong>STUDY DESIGN: </strong>We analyzed 33 095 first pediatric hospitalizations for malignancy among 43 pediatric hospitals between 1999 and 2011. The effect of demographics, disease characteristics, and weekly drug exposure (antibiotics, antacids, and chemotherapy) on HA-CDI was assessed with multivariate Cox regression. CDI was defined by the combination of International Classification of Diseases, 9th edition-Clinical Modification (ICD-9CM), CDI diagnostic assay billing code, and concurrent administration of a CDI-active antibiotic. HA-CDI was defined as CDI with assay occurring after the sixth hospital day.</p>

<p><strong>RESULTS: </strong>A total of 1736 admissions with CDI were identified, of which 380 were HA-CDI. CDI incidence increased from 1999-2006 (P = .01); however, CDI testing frequency and disease decreased from 2006-2010 (P &lt; .05). Admissions with HA-CDI had longer lengths of stay compared with those without HA-CDI (35 days vs 12 days, P &lt; .01) and greater risk of inpatient mortality (relative risk 2.3, P &lt; .01). Increased risk of HA-CDI (hazard ratio [95% CI]) was seen after exposure to the following drugs: aminoglycoside (1.357 [1.053-1.749]), third generation cephalosporin (1.518 [1.177-1.959]), cefepime (2.383 [1.839-3.089]), and proton pump inhibiting agent (1.398 [1.096-1.784]) in the prior week, and chemotherapy (1.942 [1.491-2.529]) in the 8-14 days prior to HA-CDI onset. Histamine-2 receptor antagonist exposure in the prior week was associated with decreased risk of HA-CDI (0.730 [0.584-0.912]).</p>

<p><strong>CONCLUSIONS: </strong>Despite an apparent decrease in CDI incidence from 2006-2010, HA-CDI remains prevalent and morbid among children with cancer. Recent exposure to chemotherapy, proton pump inhibitor, and certain antibiotics were independent risk factors for HA-CDI.</p>