Background A multitude of definitions determining multidrug resistance (MDR) of Gram-negative organisms exist worldwide. The definitions differ depending on their purpose and on the issueing country or organization. The MDR definitions of the European Centre for Disease Prevention and Control (ECDC) were primarily chosen to harmonize epidemiological surveillance. The German Commission of Hospital Hygiene and Infection Prevention (KRINKO) issued a national guideline which is mainly used to guide infection prevention and control (IPC) measures. The Swiss University Hospital Zurich (UHZ) - in absentia of national guidelines - developed its own definition for IPC purposes. In this study we aimed to determine the effects of different definitions of multidrug-resistance on rates of Gram-negative multidrug-resistant organisms (GN-MDRO). Methods MDR definitions of the ECDC, the German KRINKO and the Swiss University Hospital Zurich were applied on a dataset comprising isolates of Escherichia coli, Klebsiella pneumoniae, Enterobacter sp., Pseudomonas aeruginosa, and Acinetobacter baumannii complex. Rates of GN-MDRO were compared and the percentage of patients with a GN-MDRO was calculated. Results In total 11'407 isolates from a 35 month period were included. For Enterobacterales and P. aeruginosa, highest MDR-rates resulted from applying the 'ECDC-MDR' definition. 'ECDC-MDR' rates were up to four times higher compared to 'KRINKO-3/4MRGN' rates, and up to six times higher compared to UHZ rates. Lowest rates were observed when applying the 'KRINKO-4MRGN' definitions. Comparing the 'KRINKO-3/4MRGN' with the UHZ definitions did not show uniform trends, but yielded higher rates for E. coli and lower rates for P. aeruginosa. On the patient level, the percentages of GN-MDRO carriers were 2.1, 5.5, 6.6, and 18.2% when applying the 'KRINKO-4MRGN', 'UHZ-MDR', 'KRINKO-3/4MRGN', and the 'ECDC-MDR' definition, respectively. Conclusions Different MDR-definitions lead to considerable variation in rates of GN-MDRO. Differences arise from the number of antibiotic categories required to be resistant, the categories and drugs considered relevant, and the antibiotic panel tested. MDR definitions should be chosen carefully depending on their purpose and local resistance rates, as definitions guiding isolation precautions have direct effects on costs and patient care.

中文翻译：

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不同的多重耐药性 (MDR) 定义对 MDR 革兰氏阴性杆菌率的影响。


背景 世界范围内存在多种确定革兰氏阴性生物多药耐药性 (MDR) 的定义。定义根据其目的以及发行国家或组织的不同而有所不同。欧洲疾病预防和控制中心 (ECDC) 的 MDR 定义主要是为了协调流行病学监测而选择的。德国医院卫生和感染预防委员会（KRINKO）发布了国家指南，主要用于指导感染预防和控制（IPC）措施。瑞士苏黎世大学医院 (UHZ) 在缺乏国家指南的情况下为 IPC 目的制定了自己的定义。在这项研究中，我们旨在确定不同的多重耐药定义对革兰氏阴性多重耐药微生物（GN-MDRO）发生率的影响。方法 ECDC、德国 KRINKO 和瑞士苏黎世大学医院的 MDR 定义应用于包含大肠杆菌、肺炎克雷伯菌、肠杆菌属、铜绿假单胞菌和鲍曼不动杆菌复合体分离株的数据集。比较 GN-MDRO 发生率并计算 GN-MDRO 患者的百分比。结果 35 个月期间总共 11,407 个分离株被纳入。对于肠杆菌和铜绿假单胞菌，应用“ECDC-MDR”定义导致最高的 MDR 率。与“KRINKO-3/4MRGN”比率相比，“ECDC-MDR”比率高出四倍，与 UHZ 比率相比高出六倍。应用“KRINKO-4MRGN”定义时观察到最低的比率。将“KRINKO-3/4MRGN”与 UHZ 定义进行比较并没有显示出统一的趋势，但得出了较高的大肠杆菌率和较低的铜绿假单胞菌率。 在患者层面，应用“KRINKO-4MRGN”、“UHZ-MDR”、“KRINKO-3/4MRGN”和“ECDC-”时，GN-MDRO携带者的百分比分别为2.1%、5.5%、6.6%和18.2%。分别是 MDR 的定义。结论 不同的 MDR 定义导致 GN-MDRO 发生率存在很大差异。差异源于需要具有耐药性的抗生素类别的数量、被认为相关的类别和药物以及测试的抗生素组合。应根据其目的和当地耐药率仔细选择 MDR 定义，因为指导隔离预防措施的定义对成本和患者护理有直接影响。