OBJECTIVE To assess the performance of differential time to positivity (DTP) for the diagnosis of catheter-related bloodstream infections (CRBSI). METHODS From all episodes of bloodstream infections (BSI) diagnosed during a 15-year period (2003-17) those in which a paired set of blood cultures drawn from a catheter and a peripheral vein were positive for the same microorganism and had a clinically and/or microbiologically defined source were selected. To assess diagnostic discrimination ability and accuracy of DTP for CRBSI, area under the receiver operating characteristic curves (AUC) and performance characteristics of a DTP ≥2 h were computed. RESULTS A total of 512 BSI were included, of which 302 (59%) were CRBSI. Discrimination ability of DTP was low for Staphylococcus aureus (AUC 0.656 ± 0.06), coagulase-negative staphylococci (AUC 0.618 ± 0.081), enterococci (AUC 0.554 ± 0.117) and non-AmpC-producing Enterobacteriaceae (AUC 0.653 ± 0.053); moderate for Pseudomonas aeruginosa (AUC 0.841 ± 0.073), and high for AmpC-producing Enterobacteriaceae (AUC 0.944 ± 0.039). For the entire sample, DTP had a low-to-moderate discrimination ability (AUC 0.698 ± 0.024). A DTP ≥2 h has a low sensitivity for coagulase-negative staphylococci (60%) and very low for S. aureus (34%), enterococci (40%) and non-AmpC-producing Enterobacteriaceae (42%). A DTP cut-off of 1 h improved sensitivity (90%) for AmpC-producing Enterobacteriaceae. CONCLUSIONS Differential time to positivity performs well for diagnosing CRBSI only when AmpC-producing Enterobacteriaceae and P. aeruginosa are involved. Performance is low for common Gram-positive organisms and non-AmpC-producing enteric bacilli; a negative test should not be used to rule out CRBSI due to these microorganisms. A DTP ≥1 h may improve accuracy for AmpC-producing Enterobacteriaceae, particularly Enterobacter spp.

中文翻译：

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差异时间到阳性作为导管相关血流感染的常规诊断测试的性能：单中心经验。

目的评估微分阳性时间（DTP）在诊断与导管相关的血流感染（CRBSI）中的表现。方法在15年间（2003-17年）诊断出的所有血流感染（BSI）事件中，从导管和外周静脉抽取的成对血培养物对同一微生物均呈阳性，并且在临床上和/或选择微生物定义的来源。为了评估CRBSI的诊断识别能力和DTP的准确性，计算了接收器工作特征曲线（AUC）下的面积和DTP≥2 h的性能特征。结果总共包括512个BSI，其中302个（59％）是CRBSI。DTP对金黄色葡萄球菌（AUC 0.656±0.06），凝固酶阴性葡萄球菌（AUC 0）的识别能力低。618±0.081），肠球菌（AUC 0.554±0.117）和非AmpC产肠杆菌科（AUC 0.653±0.053）; 铜绿假单胞菌为中等（AUC 0.841±0.073），产AmpC的肠杆菌科为中等（AUC 0.944±0.039）。对于整个样品，DTP的分辨能力低到中等（AUC 0.698±0.024）。DTP≥2 h对凝固酶阴性葡萄球菌敏感度低（60％），对金黄色葡萄球菌（34％），肠球菌（40％）和不产生AmpC的肠杆菌科（42％）的敏感性很低。DTP截止时间为1小时可提高对产生AmpC的肠杆菌科细菌的敏感性（90％）。结论仅当涉及产生AmpC的肠杆菌科细菌和铜绿假单胞菌时，阳性反应的差异时间才能很好地诊断CRBSI。对于常见的革兰氏阳性生物和不产生AmpC的肠杆菌，其性能较低。由于这些微生物，不应使用阴性测试来排除CRBSI。DTP≥1 h可能会提高产生AmpC的肠杆菌科细菌，特别是肠杆菌属细菌的准确性。