The nosocomial pathogen Acinetobacter baumannii is a frequent cause of healthcare-acquired infections, particularly in critically ill patients, and is of serious concern due to its potential for acquired multidrug resistance. Whole-genome sequencing (WGS) is increasingly used to obtain a high-resolution view of relationships between isolates, which helps in controlling healthcare-acquired infections. Here, we conducted a retrospective study to identify epidemic situations and assess the percentage of transmission in intensive care units (ICUs). Multidrug-resistant A. baumannii (MDR-AB) were continuously isolated from the lower respiratory tract of different patients (at the first isolation in our ICU). We performed WGS, pulsed-field gel electrophoresis (PFGE), and multilocus-sequence typing (MLST) analyses to elucidate bacterial relatedness and to compare the performance of conventional methods with WGS for typing MDR-AB. From June 2017 to August 2018, A. baumannii complex strains were detected in 124 of 796 patients during their ICU stays, 103 of which were MDR-AB. Then we subjected 70 available MDR-AB strains to typing with WGS, PFGE, and MLST. Among the 70 A. baumannii isolates, 38 (54.29%) were isolated at admission, and 32(45.71%) were acquisition isolates. MLST identified 12 unique sequence types, a novel ST (ST2367) was founded. PFGE revealed 16 different pulsotypes. Finally, 38 genotypes and 23 transmissions were identified by WGS. Transmission was the main mode of MDR-AB acquisition in our ICU. Our results demonstrated that WGS was a discriminatory technique for epidemiological healthcare-infection studies. The technique should greatly benefit the identification of epidemic situations and controlling transmission events in the near future.

院内病原体 鲍曼不动杆菌是医疗保健获得性感染的常见原因，特别是在危重患者中，并且由于其潜在的获得性多药耐药性而受到严重关注。全基因组测序 (WGS) 越来越多地用于获取分离株之间关系的高分辨率视图，这有助于控制医疗保健获得性感染。在这里，我们进行了一项回顾性研究，以确定流行情况并评估重症监护病房 (ICU) 中的传播百分比。多重耐药鲍曼不动杆菌(MDR-AB) 从不同患者的下呼吸道中持续隔离（在我们 ICU 的第一次隔离时）。我们进行了 WGS、脉冲场凝胶电泳 (PFGE) 和多位点序列分型 (MLST) 分析，以阐明细菌相关性，并比较传统方法与 WGS 在分型 MDR-AB 方面的性能。2017年6月至2018年8月，鲍曼不动杆菌在 ICU 住院期间，796 名患者中有 124 名检测到复杂菌株，其中 103 名是 MDR-AB。然后我们对 70 个可用的 MDR-AB 菌株进行了 WGS、PFGE 和 MLST 分型。其中 70鲍曼不动杆菌其中，入院时分离出38株（54.29%），获得性分离株32株（45.71%）。MLST 确定了 12 种独特的序列类型，建立了一个新的 ST（ST2367）。PFGE 揭示了 16 种不同的脉搏类型。最后，WGS 确定了 38 个基因型和 23 个传输。在我们的 ICU 中，传播是 MDR-AB 获取的主要方式。我们的结果表明，WGS 是一种用于流行病学医疗保健感染研究的歧视性技术。该技术将极大地有益于在不久的将来识别流行病和控制传播事件。