Intermountain Blood and Marrow Transplant Program, LDS Hospital, Salt Lake City, UT, USA.
Department of Medicine, Division of Infectious Diseases and Clinical Epidemiology, Intermountain Healthcare, Salt Lake City, UT, USA.
Transpl Infect Dis. 2020 Aug;22(4):e13279. doi: 10.1111/tid.13279. Epub 2020 Apr 8.
Because both diarrhea due to other causes and gastrointestinal colonization with toxigenic Clostridioides difficile are common in HSCT, there is a possibility of false-positive diagnoses of C difficile infections (CDI).
We estimated the probability of a patient being colonized by toxigenic C difficile by testing non-diarrheal surveillance stools from 223 HSCT recipients and the probability that a specimen submitted for C difficile testing was not CDI by determining the number of clinical tests that returned negative from this cohort. The number of expected false-positive CDI was estimated using these probabilities and compared with observed clinical test results.
The expected false-positive and the observed numbers of positive clinical results were similar. The 20 patients diagnosed with CDI were also similar to 142 patients with diarrhea and C difficile-negative stools in number of stools on day of testing, associated symptoms, and the recorded number of days to formed stools. C difficile colonization was most commonly detected during the first week and CDI during the second. Retrospective analysis of 837 patients showed that 18 stools were submitted for each diagnosis of CDI. Ribotyping of the surveillance samples showed 17 ribotypes.
Although several assumptions could impact the accuracy of our false-positive CDI estimates, it appears that many HSCT recipients diagnosed with CDI may actually represent colonized status and an alternative cause of diarrhea. Diagnostic stewardship, including limiting CDI diagnoses to patients with positive toxin and restricting stool submissions to patients with more severe symptoms, may decrease the number of false-positive diagnoses.
由于其他原因引起的腹泻和产毒艰难梭菌的胃肠道定植在 HSCT 中都很常见，因此有可能误诊为艰难梭菌感染（CDI）。
我们通过检测 223 例 HSCT 受者的非腹泻性监测粪便，估计了患者被产毒艰难梭菌定植的概率，通过确定从该队列中返回阴性的临床检测数量，确定提交用于艰难梭菌检测的标本不是 CDI 的概率。使用这些概率来估计预期的假阳性 CDI 数量，并将其与观察到的临床检测结果进行比较。
预期的假阳性和观察到的阳性临床结果数量相似。20 例诊断为 CDI 的患者与 142 例腹泻且粪便艰难梭菌阴性的患者在检测日粪便数量、相关症状以及记录的粪便成型天数方面也相似。艰难梭菌定植最常见于第 1 周，CDI 最常见于第 2 周。对 837 例患者的回顾性分析显示，每诊断 1 例 CDI 就需要提交 18 份粪便。监测样本的核糖体分型显示有 17 种核糖体型。
尽管有几个假设可能会影响我们对假阳性 CDI 估计的准确性，但似乎许多被诊断为 CDI 的 HSCT 受者实际上可能代表定植状态和另一种腹泻原因。诊断管理，包括将 CDI 诊断限于毒素阳性患者，并将粪便提交限于症状更严重的患者，可能会减少假阳性诊断的数量。
