Lo Calvin Ka-Fung, Sritharan Ashwin, Zhang Jiesi, Li Nicole, Zhang Cindy, Wang Frank, Loeb Mark, Bai Anthony D
Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC, Canada.
Michael G. DeGroote Undergraduate School of Medicine, McMaster University, Hamilton, ON, Canada.
JAC Antimicrob Resist. 2024 May 6;6(3):dlae069. doi: 10.1093/jacamr/dlae069. eCollection 2024 Jun.
The cefazolin inoculum effect (CzIE) is a phenomenon whereby some MSSA isolates demonstrate resistance to cefazolin when a high bacterial inoculum is used for susceptibility testing. The clinical significance of this phenotypic phenomenon remains unclear. We conducted a systematic review to answer the following question: In patients with serious MSSA infection treated with cefazolin, does infection due to CzIE-positive MSSA isolates result in worse clinical outcomes than infection due to CzIE-negative MSSA isolates?
Ovid MEDLINE, Embase, Cochrane CENTRAL, medRxiv and bioRxiv were searched from inception until 12 April 2023. Studies were included if they tested for CzIE in clinical isolates from MSSA infections in humans. Two independent reviewers extracted data and conducted risk-of-bias assessment. Main outcomes were treatment failure and mortality. Pooling of study estimates was not performed given the heterogeneity of patient populations and outcome definitions.
Twenty-three observational studies were included. CzIE presence amidst MSSA isolates ranged from 0% to 55%. There was no statistically significant mortality difference in two studies that compared MSSA infections with and without CzIE, with ORs ranging from 0.72 to 19.78. Of four studies comparing treatment failure, ORs ranged from 0.26 to 13.00. One study showed a significantly higher treatment failure for the CzIE group, but it did not adjust for potential confounders.
The evidence on CzIE is limited by small observational studies. In these studies, CzIE did not predict higher mortality in MSSA infections treated with cefazolin. Our findings do not support CzIE testing in clinical practice currently.
头孢唑啉接种量效应（CzIE）是一种现象，即当使用高细菌接种量进行药敏试验时，一些甲氧西林敏感金黄色葡萄球菌（MSSA）分离株对头孢唑啉表现出耐药性。这种表型现象的临床意义仍不清楚。我们进行了一项系统评价，以回答以下问题：在接受头孢唑啉治疗的严重MSSA感染患者中，由CzIE阳性MSSA分离株引起的感染是否比由CzIE阴性MSSA分离株引起的感染导致更差的临床结局？
检索Ovid MEDLINE、Embase、Cochrane CENTRAL、medRxiv和bioRxiv数据库，检索时间从数据库建立至2023年4月12日。纳入对人类MSSA感染临床分离株进行CzIE检测的研究。两名独立的审阅者提取数据并进行偏倚风险评估。主要结局为治疗失败和死亡率。鉴于患者群体和结局定义的异质性，未进行研究估计值的合并。
纳入23项观察性研究。MSSA分离株中CzIE的存在率为0%至55%。两项比较有无CzIE的MSSA感染的研究中，死亡率无统计学显著差异，比值比（OR）范围为0.72至19.78。四项比较治疗失败的研究中，OR范围为0.26至13.00。一项研究显示CzIE组的治疗失败率显著更高，但未对潜在混杂因素进行校正。
关于CzIE的证据受小型观察性研究的限制。在这些研究中，CzIE并未预测头孢唑啉治疗的MSSA感染的更高死亡率。我们的研究结果不支持目前在临床实践中进行CzIE检测。
