278
Table 3. Utilization of C. difficile Testing Restrictions and Hospital Characteristics Relative to Hospital C. difficile Testing Strategy Hospital Characteristic
Restrict C. difficile testing to unformed stools Age-based C. difficile testing restrictions University hospital
Freestanding children’s hospital <350 hospital beds
Toxin Testinga 53/56 (95%) 28/56 (50%) 37/60 (62%) 35/60 (58%) 39/60 (65%)
NAAT Aloneb 88/95 (93%) 47/93 (51%) 62/99 (63%) 53/99 (54%) 64/99 (65%)
Note. NAAT, nucleic acid amplification test; PCR, polymerase chain reaction. aToxin test used either as a single test or part of a multistep algorithm. bUsed either an NAAT assay that only detects C. difficile, or a multiplex PCR panel that includes C. difficile, without initial or confirmatory toxin testing.
Larry K. Kociolek et al
P Value .63 .95 .90 .56 .97
Results
Among the 345 active PID EIN members to whom the survey was sent, 196 (57%) responded; 162 of these (83%) were aware of their institutional policies for CDI testing and management and com- pleted the survey. Table 1 lists the respondent and nonrespondent demographics; there were no statistically significant differences between respondents and nonrespondents (P values ranged from 0.38 to 0.83 for all demographics listed in Table 1). Table 2 lists the C. difficile testing strategies (ie, single test vs
multistep algorithm and specific assays used) reported by the 159 of 162 eligible respondents (98%) who knew their institution’s CDI testing strategy. Irrespective of the specific strategy and assay used, 99 of 159 respondents (62%) utilize NAAT without toxin testing. Although 60 of 159 (38%) respondents utilize toxin testing, 36 of these 60 (60%) respondents initially test stool with a combined glutamate dehydrogenase (GDH, C. difficile common antigen) and toxin EIA but follow up with NAAT as an arbitrator of GDH-positive, toxin-negative stools. Thus, toxin EIA is utilized to rule in CDI, but NAAT is used to rule out CDI with this multi- step algorithm. Among the 87 respondents providing information about their institution’s use of a multiplex PCR panel for diarrheal pathogens, 39 (45%) report that they always suppress the C. difficile PCR result from this assay. Among the 48 respondents whose institutions report the C. difficile PCR result from the multiplex PCR panel, 13 (27%) require the healthcare provider to specifically request C. difficile PCR results, whereas 35 (73%) report the C. difficile PCR result even if C. difficile testing was not specifically requested. Among the 153 respondents aware of symptom-based restric-
tions on C. difficile testing, 143 (93%) reported that only unformed stools were tested for C. difficile at their institution. Among the 151 respondents aware of age-based restrictions on C. difficile testing, 75 (50%) reported that their institution employed age-based restrictions. Testing was limited to patients older than the follow- ing: 3 months (n = 1, 1%), 12 months (n = 62, 83%), 24 months (n = 11, 14%), and 36 months (n = 1, 1%). Adoption of age-based restrictions was not associated with being a university-affiliated hospital (52% vs 45%; P = 0.43), a freestanding children’s hospital (53% vs 45%; P = 0.28), or a hospital with >350 beds (52% vs 49%; P = 0.69). Testing restrictions and hospital characteristics (Table 3)were
similar among respondents whose institutions utilize NAAT alone (either NAAT for only C. difficile or a multiplex PCR panel that includes C. difficile) compared to those whose institutions use toxin testing (either as a single test or part of a multi-step algorithm). Among the 143 respondents whose institutions have a neonatal intensive care unit (NICU) and are aware of C. difficile testing
policies for NICU patients, 26 (16%) permit testing of these infants. Respondents reported that if a patient in the NICUtests positive, the patient is managed with contact isolation (n = 17, 65%), single patient room or patient cohorting (n = 5, 19%), and/or antibiotic therapy for CDI (n = 12, 46%). Only 1 respondent (1%) indicated that their institution rou-
tinely tests asymptomatic children to identify C. difficile carriage. This respondent reported that their institution tests for carriage in patients with a malignancy or bone marrow transplant. The only action that occurs when asymptomatic carriage of C. difficile is detected is enhanced environmental cleaning (eg, frequency and/or type of disinfectant). If a known asymptomatic carrier subsequently develops diarrhea, that patient receives empiric CDI treatment without repeat testing. Asymptomatic carriers are not reported to the National Healthcare Safety Network (NHSN).
Discussion
Updated clinical practice guidelines forCDI were recently endorsed by the IDSA and the Society for Healthcare Epidemiology of America (SHEA).4 Compared to the previous 2010 guideline, the updated document included clinical practice guidance for pediatric populations. Although the guideline authors acknowledged the benefits and drawbacks of both toxin EIAs andNAATs, a single test was not wholly endorsed. NAATs (alone or as part of a multistep algorithm) were recommended only if the hospital had pre-agreed criteria for submitting stool specimens for C. difficile testing. The purpose of these prearranged criteria is to limit C. difficile testing in patients with low likelihood of CDI and avoid detection of asymptomatic carriage. In institutions without pre-agreed criteria for submitting stool specimens for C. difficile testing, stool toxin testing as part of a multistep algorithm was recommended. These survey data, gathered shortly before publication of the updated IDSA/SHEA guidelines,4 provide information about the prevalence of CDI diagnostic practices in the United States as it relates to limit- ing detection of asymptomatic carriage in children. Thus, these data inform opportunities for improving C. difficile diagnostic steward- ship, particularly among institutions utilizingNAATs for C. difficile diagnosis, in accordance with the recently updated guidelines. Because adoption of diagnostic stewardship practices is not associ- ated with various hospital characteristics (eg, freestanding child- ren’s hospital, hospital size or university affiliation), our data suggest that need for diagnostic stewardship practices is a relatively pervasive issue. These data suggest that many PID physicians have an oppor-
tunity to advocate for institutional changes to C. difficile diagnostic testing practices that may reduce the misdiagnosis of CDI in asymptomatic carriers. Although routine testing for
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