BACKGROUND Acinetobacter baumannii is a Gram-negative opportunistic pathogen with a notorious reputation of being resistant to antimicrobial agents. The capability of A. baumannii to persist and disseminate between healthcare settings has raised a major concern worldwide. METHODS Our study investigated the antibiotic resistance features and molecular epidemiology of 52 clinical isolates of A. baumannii collected in Pakistan between 2013 and 2015. Antimicrobial susceptibility patterns were determined by the agar disc diffusion method. Comparative sequence analyses of the ampC and blaOXA-51-like alleles were used to assign the isolates into clusters. The whole genomes of 25 representative isolates were sequenced using the MiSeq Desktop Sequencer. Free online applications were used to determine the phylogeny of genomic sequences, retrieve the multilocus sequence types (ST), and detect acquired antimicrobial resistance genes. RESULTS Overall, the isolates were grouped into 7 clusters and 3 sporadic isolates. The largest cluster, Ab-Pak-cluster-1 (blaOXA-66 and ISAba1-ampC-19) included 24 isolates, belonged to ST2 and International clone (IC) II, and was distributed between two geographical far-off cities, Lahore and Peshawar. Ab-Pak-clusters-2 (blaOXA-66, ISAba1-ampC-2), and -3 (blaOXA-66, ISAba1-ampC-20) and the individual isolate Ab-Pak-Lah-01 (ISAba1-blaOXA-66, ISAba1-ampC-2) were also assigned to ST2 and IC II. On the other hand, Ab-Pak-clusters-4 (blaOXA-69, ampC-1), -5 (blaOXA-69, ISAba1-ampC-78), and -6A (blaOXA-371, ISAba1-ampC-3) belonged to ST1, while Ab-Pak-cluster-6B (blaOXA-371, ISAba1-ampC-8) belonged to ST1106, with both ST1 and ST1106 being members of IC I. Five isolates belonged to Ab-Pak-cluster-7 (blaOXA-65, ampC-43). This cluster corresponded to ST158, showed a well-delineated position on the genomic phylogenetic tree, and was equipped with several antimicrobial resistance genes including blaOXA-23 and blaGES-11. CONCLUSIONS Our study detected the occurrence of 7 clusters of A. baumannii in Pakistan. Altogether, 6/7 of the clusters and 45/52 (86.5%) of the isolates belonged to IC I (n = 9) or II (n = 36), making Pakistan no exception to the global domination of these two clones. The onset of ST158 in Pakistan marked a geographical dispersal of this clone beyond the Middle East and brought up the need for a detailed characterization.

中文翻译：

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巴基斯坦鲍曼不动杆菌临床分离株的分子流行病学和抗菌素耐药性特征。

背景技术鲍曼不动杆菌是革兰氏阴性机会病原体，以对抗菌剂具有抗性而著名。鲍曼不动杆菌在医疗机构之间持久和传播的能力引起了全世界的广泛关注。方法我们研究了2013年至2015年在巴基斯坦收集的52例鲍曼不动杆菌临床分离株的抗生素耐药性特征和分子流行病学。采用琼脂圆盘扩散法确定了抗生素的敏感性模式。ampC和blaOXA-51样等位基因的比较序列分析用于将分离株分为簇。使用MiSeq桌面测序仪对25个代表性分离株的整个基因组进行测序。免费的在线应用程序用于确定基因组序列的系统发育，检索多基因座序列类型（ST），并检测获得的抗菌素耐药基因。结果总体上，分离株分为7个簇和3个散发分离株。最大的集群Ab-Pak-cluster-1（blaOXA-66和ISAba1-ampC-19）包括24个分离株，分别属于ST2和国际克隆（IC）II，分布在两个遥远的城市拉合尔和白沙瓦。Ab-Pak-clusters-2（blaOXA-66，ISAba1-ampC-2）和-3（blaOXA-66，ISAba1-ampC-20）和独立的Ab-Pak-Lah-01（ISAba1-blaOXA-66） （ISAba1-ampC-2）也分配给ST2和IC II。另一方面，Ab-Pak-clusters-4（blaOXA-69，ampC-1），-5（blaOXA-69，ISAba1-ampC-78）和-6A（blaOXA-371，ISAba1-ampC-3）属于ST1，而Ab-Pak-cluster-6B（blaOXA-371，ISAba1-ampC-8）属于ST1106，ST1和ST1106均为IC I的成员。五个分离物属于Ab-Pak-cluster-7（blaOXA-65，ampC-43）。该簇对应于ST158，在基因组系统树上显示出良好的位置，并配备了包括blaOXA-23和blaGES-11在内的几种抗菌素耐药基因。结论我们的研究检测到巴基斯坦发生了7个鲍曼不动杆菌簇。总共有6/7的簇和45/52（86.5％）的分离株属于IC I（n = 9）或II（n = 36），这使得巴基斯坦在这两个克隆的全球统治中也不例外。ST158在巴基斯坦的爆发标志着该克隆的地理分布在中东以外，并提出了详细表征的需求。在基因组系统树上显示出良好的定位，并配备了几种抗药性基因，包括blaOXA-23和blaGES-11。结论我们的研究检测到巴基斯坦发生了7个鲍曼不动杆菌簇。总共有6/7的簇和45/52（86.5％）的分离株属于IC I（n = 9）或II（n = 36），这使得巴基斯坦在这两个克隆的全球统治中也不例外。ST158在巴基斯坦的爆发标志着该克隆的地理分布在中东以外，并提出了详细表征的需求。在基因组系统树上显示出良好的定位，并配备了几种抗药性基因，包括blaOXA-23和blaGES-11。结论我们的研究检测到巴基斯坦发生了7个鲍曼不动杆菌簇。总共有6/7的簇和45/52（86.5％）的分离株属于IC I（n = 9）或II（n = 36），这使得巴基斯坦在这两个克隆的全球统治中也不例外。ST158在巴基斯坦的爆发标志着该克隆的地理分布在中东以外，并提出了详细表征的需求。5％的分离株属于IC I（n = 9）或II（n = 36），这使得巴基斯坦在这两个克隆的全球统治中也不例外。ST158在巴基斯坦的爆发标志着该克隆的地理分布在中东以外，并提出了详细表征的需求。5％的分离株属于IC I（n = 9）或II（n = 36），这使得巴基斯坦在这两个克隆的全球统治中也不例外。ST158在巴基斯坦的爆发标志着该克隆的地理分布在中东以外，并提出了详细表征的需求。