Karatuna O, Dance D A B, Matuschek E, Åhman J, Turner P, Hopkins J, Amornchai P, Wuthiekanun V, Cusack T-P, Baird R, Hennessy J, Norton R, Armstrong M, Zange S, Zoeller L, Wahab T, Jacob D, Grunow R, Kahlmeter G
EUCAST Development Laboratory, Växjö, Sweden.
Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit, Vientiane, Lao People's Democratic Republic; Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK; Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK.
Clin Microbiol Infect. 2020 Jul 9. doi: 10.1016/j.cmi.2020.07.001.
Melioidosis, caused by Burkholderia pseudomallei, requires intensive antimicrobial treatment. However, standardized antimicrobial susceptibility testing (AST) methodology based on modern principles for determining breakpoints and ascertaining performance of methods are lacking for B. pseudomallei. This study aimed to establish MIC and zone diameter distributions on which to set epidemiological cut-off (ECOFF) values for B. pseudomallei using standard EUCAST methodology for non-fastidious organisms.
Non-consecutive, non-duplicate clinical B. pseudomallei isolates (9-70 per centre) were tested at eight study centres against eight antimicrobials by broth microdilution (BMD) and the EUCAST disc diffusion method. Isolates without and with suspected resistance mechanisms were deliberately selected. The EUCAST Development Laboratory ensured the quality of study materials, and provided guidance on performance of the tests and interpretation of results. Aggregated results were analysed according to EUCAST recommendations to determine ECOFFs.
MIC and zone diameter distributions were generated using BMD and disc diffusion results obtained for 361 B. pseudomallei isolates. MIC and zone diameter ECOFFs (mg/L; mm) were determined for amoxicillin-clavulanic acid (8; 22), ceftazidime (8; 22), imipenem (2; 29), meropenem (2; 26), doxycycline (2; none), tetracycline (8; 23), chloramphenicol (8; 22) and trimethoprim-sulfamethoxazole (4; 28).
We have validated the use of standard BMD and disc diffusion methodology for AST of B. pseudomallei. The MIC and zone diameter distributions generated in this study allowed us to establish MIC and zone diameter ECOFFs for the antimicrobials studied. These ECOFFs served as background data for EUCAST to set clinical MIC and zone diameter breakpoints for B. pseudomallei.
类鼻疽病由伯克霍尔德菌引起，需要强化抗菌治疗。然而，对于伯克霍尔德菌，缺乏基于现代原理来确定断点和评估方法性能的标准化抗菌药物敏感性试验（AST）方法。本研究旨在使用针对非苛养菌的标准欧洲抗菌药物敏感性试验委员会（EUCAST）方法，建立类鼻疽伯克霍尔德菌的最低抑菌浓度（MIC）和抑菌圈直径分布，以此来设定流行病学临界值（ECOFF）。
在八个研究中心，通过肉汤微量稀释法（BMD）和EUCAST纸片扩散法，对非连续、非重复的临床类鼻疽伯克霍尔德菌分离株（每个中心9 - 70株）进行针对八种抗菌药物的测试。特意选择了没有和有疑似耐药机制的分离株。EUCAST研发实验室确保了研究材料的质量，并提供了关于测试操作和结果解读的指导。根据EUCAST的建议对汇总结果进行分析以确定ECOFF。
利用361株类鼻疽伯克霍尔德菌分离株的BMD和纸片扩散结果生成了MIC和抑菌圈直径分布。确定了阿莫西林 - 克拉维酸（8；22）、头孢他啶（8；22）、亚胺培南（2；29）、美罗培南（2；26）、多西环素（2；无）、四环素（8；23）、氯霉素（8；22）和甲氧苄啶 - 磺胺甲恶唑（4；28）的MIC和抑菌圈直径ECOFF（mg/L；mm）。
我们验证了标准BMD和纸片扩散法用于类鼻疽伯克霍尔德菌AST的有效性。本研究中生成的MIC和抑菌圈直径分布使我们能够为所研究的抗菌药物确定MIC和抑菌圈直径ECOFF。这些ECOFF作为EUCAST设定类鼻疽伯克霍尔德菌临床MIC和抑菌圈直径断点的背景数据。
