Parisio Eva Maria, Camarlinghi Giulio, Coppi Marco, Niccolai Claudia, Antonelli Alberto, Nardone Maria, Vettori Chiara, Giani Tommaso, Mattei Romano, Rossolini Gian Maria
Clinical Chemistry and Microbiology Analysis Unit, San Luca Hospital, USL Toscana Nord Ovest, Lucca, Italy.
Department of Experimental and Clinical Medicine, University of Florence, Florence, Italy; Microbiology and Virology Unit, Florence Careggi University Hospital, Florence, Italy.
Clin Microbiol Infect. 2020 Dec 5. doi: 10.1016/j.cmi.2020.11.029.
To compare fosfomycin susceptibility testing with the commercial agar dilution (AD) test, AD Fosfomycin (Liofilchem, Roseto degli Abruzzi, Italy) and the reference AD method, using a collection of multidrug-resistant (MDR) Enterobacterales and Pseudomonas aeruginosa clinical isolates.
The collection included 119 carbapenemase-producing Enterobacterales, 53 Enterobacterales producing acquired AmpC-type and/or extended-spectrum β-lactamases and 38 carbapenemase-producing P. aeruginosa, including representatives of different high-risk clones. AD Fosfomycin and AD reference method (ISO 20776-1:2019) were performed starting from the same microbial suspension. Results were interpreted according to EUCAST clinical breakpoints (10.0). Essential agreement (EA), category agreement (CA) and error rates were calculated as described by the International Organization for Standardization.
Of 172 Enterobacterales, 143 (83.1%, including 92.9% (52 of 56) of the NDM-producers and 84.2% (48 of 57) of the KPC-producers) were susceptible to fosfomycin using reference AD. A CA of 91.9% (158 of 172; 95% CI 87.1%-95.3%) and an EA of 92.5% (136 of 147; 95% CI 87.4%-96.0%), respectively, were calculated for the commercial AD Fosfomycin test, with 9.8% (14 of 128) of major errors and no very major errors (0 of 29). Overall, 86.8% (33 of 38) of P. aeruginosa showed a fosfomycin MIC ≤128 mg/L using reference AD. An EA of 84.8% (95% CI 66.3%-92.0%) was calculated for the commercial AD Fosfomycin test, with a CA of 100% (95% CI 93.6%-100%) when considering a tentative breakpoint at 128 mg/L.
AD Fosfomycin showed an overall good concordance compared with reference AD.
使用一组耐多药（MDR）肠杆菌科细菌和铜绿假单胞菌临床分离株，将磷霉素药敏试验与商业琼脂稀释法（AD）试验、AD磷霉素（Liofilchem，意大利阿布鲁齐大区罗塞托）以及参考AD方法进行比较。
该收集样本包括119株产碳青霉烯酶的肠杆菌科细菌、53株产获得性AmpC型和/或超广谱β-内酰胺酶的肠杆菌科细菌以及38株产碳青霉烯酶的铜绿假单胞菌，包括不同高风险克隆的代表菌株。从相同的微生物悬液开始进行AD磷霉素和AD参考方法（ISO 20776-1:2019）检测。结果根据欧洲抗菌药物敏感性试验委员会（EUCAST）临床断点（10.0）进行解释。按照国际标准化组织的描述计算基本一致性（EA）、类别一致性（CA）和错误率。
在172株肠杆菌科细菌中，使用参考AD法检测，143株（83.1%，包括92.9%（56株中的52株）的NDM生产者和84.2%（57株中的48株）的KPC生产者）对磷霉素敏感。商业AD磷霉素试验的CA为91.9%（172株中的158株；95%CI 87.1%-95.3%），EA为92.5%（147株中的136株；95%CI 87.4%-96.0%），主要错误率为9.8%（128株中的14株），无非常严重错误（29株中的0株）。总体而言，使用参考AD法检测，86.8%（38株中的33株）铜绿假单胞菌的磷霉素MIC≤128mg/L。商业AD磷霉素试验的EA为84.8%（95%CI 66.3%-92.0%），当考虑128mg/L的暂定断点时，CA为100%（95%CI 93.6%-100%）。
与参考AD法相比，AD磷霉素总体一致性良好。
