Roy France Emilie, Berteau Tammy, Bestman-Smith Julie, Grandjean Lapierre Simon, Dufresne Simon Frédéric, Domingo Marc-Christian, Leduc Jean-Michel
Department of Microbiology, Infectious Diseases and Immunology, Faculty of Medicine, Université Laval, Quebec, Canada.
Centre Hospitalier Universitaire de Québec-Université Laval, Quebec, Canada.
J Clin Microbiol. 2021 Jul 19;59(8):e0025921. doi: 10.1128/JCM.00259-21.
Aerococcus urinae is a urinary pathogen with well-described resistance to fluoroquinolones. This study aimed to validate the gradient diffusion (GD) method (Etest) on cation-adjusted Mueller-Hinton agar with 5% sheep blood for testing the susceptibilities of Aerococcus urinae to the antimicrobial agents ciprofloxacin and levofloxacin and to compare the Etest to the broth microdilution (BMD) method from CLSI document M45-A3. Agar dilution (AD), as recommended by EUCAST, was used as an alternative reference method to arbitrate discrepancies or address technical issues. Aerococcus urinae isolates from urinary specimens were prospectively collected between June 2016 and December 2017 from six hospitals in Quebec, Canada, and identifications were confirmed using Vitek MS with the IVD 3.0 database. Of the 207 isolates tested using BMD, 37 (17.9%) showed trailing and 19 (9.2%) showed insufficient growth; these were tested using AD. Also, 38 isolates (18.4%) for ciprofloxacin and 13 isolates (6.3%) for levofloxacin showed a lack of essential or categorical agreement between the Etest and BMD and were also tested by AD. By use of a combined reference method (BMD or AD), the susceptibility rates of Aerococcus urinae were 82.6% and 81.6% for ciprofloxacin and levofloxacin, respectively. Categorical agreement between GD and the combined reference methods was 95.2% for ciprofloxacin and 97.1% for levofloxacin, with no very major error identified. Major and minor error rates were 0.6% and 4.3% for ciprofloxacin and 1.2% and 1.9% for levofloxacin. Overall, antimicrobial susceptibility testing (AST) using the Etest on sheep blood agar showed good agreement with the reference methods and can be considered by clinical laboratories wishing to perform AST on Aerococcus urinae isolates.
尿液气球菌是一种对氟喹诺酮类药物耐药性已明确的泌尿道病原体。本研究旨在验证在含5%羊血的阳离子调节Mueller-Hinton琼脂上的梯度扩散（GD）法（Etest），用于检测尿液气球菌对环丙沙星和左氧氟沙星这两种抗菌药物的敏感性，并将Etest与CLSI文件M45-A3中的肉汤微量稀释（BMD）法进行比较。按照欧盟药敏试验委员会（EUCAST）的建议，琼脂稀释法（AD）被用作替代参考方法，以仲裁差异或解决技术问题。2016年6月至2017年12月期间，前瞻性地从加拿大魁北克的六家医院收集尿液标本中的尿液气球菌分离株，并使用Vitek MS和IVD 3.0数据库进行鉴定确认。在使用BMD检测的207株分离株中，37株（17.9%）出现拖尾现象，19株（9.2%）生长不足；这些菌株使用AD进行检测。此外，环丙沙星的38株分离株（18.4%）和左氧氟沙星的13株分离株（6.3%）在Etest和BMD之间显示出缺乏基本或绝对一致性，也通过AD进行检测。通过使用联合参考方法（BMD或AD），尿液气球菌对环丙沙星和左氧氟沙星的敏感率分别为82.6%和81.6%。GD与联合参考方法之间的绝对一致性，环丙沙星为95.2%，左氧氟沙星为97.1%，未发现非常重大误差。环丙沙星的主要和次要误差率分别为0.6%和4.3%，左氧氟沙星的主要和次要误差率分别为1.2%和1.9%。总体而言，在羊血琼脂上使用Etest进行抗菌药物敏感性试验（AST）与参考方法显示出良好的一致性，希望对尿液气球菌分离株进行AST的临床实验室可以考虑采用该方法。
