比较用于证明金黄色葡萄球菌对青霉素敏感性的表型方法。

A comparison of phenotypic methods to demonstrate penicillin susceptibility in Staphylococcus aureus.

作者信息

Hettiarachchi Ravin, Allerton Julie, McIver Christopher, Rafferty Dianne, Taylor Peter, Stevens Robert

机构信息

Department of Microbiology, New South Wales Health Pathology, St George Hospital, Sydney, NSW, Australia; School of Biomedical Sciences, University of NSW, Sydney, NSW, Australia.

Department of Microbiology, New South Wales Health Pathology, St George Hospital, Sydney, NSW, Australia.

出版信息

Pathology. 2025 Aug;57(5):630-636. doi: 10.1016/j.pathol.2024.12.636. Epub 2025 Feb 22.

DOI:10.1016/j.pathol.2024.12.636

PMID:40155262

Abstract

The aim of this study was to assess the performance of phenotypic methods to demonstrate penicillin susceptibility in Staphylococcus aureus isolates using polymerase chain reaction (PCR) as a reference. A total of 126 S. aureus isolates were categorised as penicillin-susceptible S. aureus (PSSA), methicillin-susceptible S. aureus (MSSA) and methicillin-resistant S. aureus (MRSA) using blaZ and mecA PCR. The minimum inhibitory concentration (MIC) of penicillin for each isolate was determined by broth microdilution (BMD) and agar dilution (AD) methods. Qualitative susceptibility was determined by blinded disc diffusion testing using Calibrated Dichotomous Sensitivity (CDS), Clinical Laboratory Standards Institute (CLSI) and the European Committee on Antimicrobial Susceptibility Testing (EUCAST) methods. Categorical agreement (CA) rate, major error (ME) rate and very major error (VME) rate were calculated. These isolates were characterised into 66 PSSA, 38 MSSA and 22 MRSA by molecular testing. High rates of VME (9.6%) were encountered using BMD and AD, with 20% of penicillin-resistant S. aureus isolates having a penicillin MIC ≤0.125 mg/L. There was no VME using disc diffusion methods with high level of agreement of interpretation by three separate plate readers. CA rate using CLSI was 98.6% with 1.4% ME rate, for CDS CA rate was 97.6% with 2.4% ME rate, and for EUCAST CA rate was 93.8% with 6.2% ME rate. All methods improved with consensus reporting after considering interpretation by the plate readers. Laboratories can confidently report penicillin susceptibility in the majority of clinical S. aureus isolates based on disc diffusion testing using CLSI, EUCAST or CDS methodologies. Consensus reporting by independent plate readers may improve CA of disc diffusion testing. Penicillin MIC determination should not be used to demonstrate penicillin susceptibly in S. aureus isolates without confirmation by disc diffusion or molecular methods.

摘要

本研究的目的是评估以聚合酶链反应（PCR）为参照时，表型方法检测金黄色葡萄球菌分离株中青霉素敏感性的性能。使用blaZ和mecA PCR将总共126株金黄色葡萄球菌分离株分为青霉素敏感金黄色葡萄球菌（PSSA）、甲氧西林敏感金黄色葡萄球菌（MSSA）和甲氧西林耐药金黄色葡萄球菌（MRSA）。通过肉汤微量稀释（BMD）和琼脂稀释（AD）方法测定各分离株青霉素的最低抑菌浓度（MIC）。采用校准二分敏感度（CDS）、临床实验室标准协会（CLSI）和欧洲抗菌药物敏感性试验委员会（EUCAST）方法通过盲法纸片扩散试验确定定性敏感性。计算分类一致性（CA）率、主要错误（ME）率和极主要错误（VME）率。通过分子检测将这些分离株分为66株PSSA、38株MSSA和22株MRSA。使用BMD和AD时遇到较高的VME率（9.6%），20% 的青霉素耐药金黄色葡萄球菌分离株青霉素MIC≤0.125 mg/L。使用纸片扩散法时未出现VME率情况，三位独立的平板读数器对结果解读的一致性较高。使用CLSI时CA率为98.6%，ME率为1.4%；使用CDS时CA率为97.6%，ME率为2.4%；使用EUCAST时CA率为93.8%，ME率为6.2%。在考虑平板读数器的解读结果后，所有方法通过一致性报告均有所改进。基于使用CLSI、EUCAST或CDS方法的纸片扩散试验，实验室可以放心地报告大多数临床金黄色葡萄球菌分离株的青霉素敏感性。由独立平板读数器进行的一致性报告可能会提高纸片扩散试验的CA率。在未通过纸片扩散或分子方法确认的情况下，不应使用青霉素MIC测定来证明金黄色葡萄球菌分离株对青霉素敏感。