Chuang Yu-Chung, Sheng Wang-Huei, Lauderdale Tsai-Ling, Li Shu-Yin, Wang Jann-Tay, Chen Yee-Chun, Chang Shan-Chwen
Department of Internal Medicine, National Taiwan University Hospital, Taipei, Taiwan.
Division of Clinical Research, National Health Research Institutes, Zhunan, Taiwan.
J Microbiol Immunol Infect. 2014 Aug;47(4):324-32. doi: 10.1016/j.jmii.2013.03.008. Epub 2013 May 28.
Emerging carbapenem resistance among Acinetobacter baumannii clinical isolates is a worldwide problem. Infections caused by A. baumannii are increasing and demonstrate high mortality rates. This study aimed to establish a nationwide surveillance of antimicrobial susceptibility, carbapenemase genes, and clonal relationships of A. baumannii clinical isolates in Taiwan.
Clinical isolates of Acinetobacter calcoaceticus-A. baumannii (ACB) complex collected by the Taiwan Surveillance of Antimicrobial Resistance-V program between July 2006 and September 2006 were used in this study. Genospecies identification was verified by 16S-23S rRNA intergenic-spacer sequences. Carbapenemase genes were detected by polymerase chain reaction. Pulsed-field gel electrophoresis and multilocus sequence typing (MLST) was applied for identification of clonal relationships.
Among the 151 ACB-complex isolates collected, 134 (88.7%) were A. baumannii, 12 (8.0%) were A. pittii, and five (3.3%) were A. nosocomialis. A. baumannii isolates showed higher resistance rates to ciprofloxacin, amikacin, and ampicillin/sulbactam than A. pittii or A. nosocomialis (all p < 0.001). The most commonly detected carbapenemase genes were bla(OxA-51) (n = 135), followed by bla(OxA-24) (n = 4), bla(OxA-23) (n = 2), and bla(OxA-58) (n = 1). Three major A. baumannii clones were found throughout Taiwan, and showed significantly higher resistance rates to ciprofloxacin, amikacin, and ampicillin/sulbactam than the other A. baumannii isolates (100% vs. 68.7%, p < 0.001; 98.4% vs. 61.5%, p < 0.001; and 66.7% vs. 39.8%, p = 0.004; respectively). MLST showed that these major clones were sequence type 2 and belonged to international clonal complex 2.
Our results demonstrate clonal spreading of A. baumannii in Taiwan hospitals and that these clones were more resistant to many antimicrobial agents. Efforts to prevent and control A. baumannii colonization/infections and prudent use of antibiotics to reduce antimicrobial selective pressure should be emphasized.
鲍曼不动杆菌临床分离株中出现的碳青霉烯耐药性是一个全球性问题。鲍曼不动杆菌引起的感染不断增加，且死亡率很高。本研究旨在对台湾地区鲍曼不动杆菌临床分离株的抗菌药物敏感性、碳青霉烯酶基因及克隆关系进行全国性监测。
本研究使用了2006年7月至2006年9月期间通过台湾抗菌药物耐药性监测-V计划收集的醋酸钙不动杆菌-鲍曼不动杆菌（ACB）复合体的临床分离株。通过16S-23S rRNA基因间隔序列验证基因种属鉴定。通过聚合酶链反应检测碳青霉烯酶基因。应用脉冲场凝胶电泳和多位点序列分型（MLST）鉴定克隆关系。
在收集的151株ACB复合体分离株中，134株（88.7%）为鲍曼不动杆菌，12株（8.0%）为皮氏不动杆菌，5株（3.3%）为医院不动杆菌。鲍曼不动杆菌分离株对环丙沙星、阿米卡星和氨苄西林/舒巴坦的耐药率高于皮氏不动杆菌或医院不动杆菌（所有p<0.001）。最常检测到的碳青霉烯酶基因是bla(OxA-51)（n = 135），其次是bla(OxA-24)（n = 4）、bla(OxA-23)（n = 2）和bla(OxA-58)（n = 1）。在台湾各地发现了三个主要的鲍曼不动杆菌克隆，它们对环丙沙星、阿米卡星和氨苄西林/舒巴坦的耐药率显著高于其他鲍曼不动杆菌分离株（分别为100%对68.7%，p<0.001；98.4%对61.5%，p<0.001；66.7%对39.8%，p = 0.004）。MLST显示这些主要克隆为序列型2，属于国际克隆复合体2。
我们的结果表明鲍曼不动杆菌在台湾医院中存在克隆传播，且这些克隆对多种抗菌药物更具耐药性。应强调预防和控制鲍曼不动杆菌定植/感染的努力以及谨慎使用抗生素以降低抗菌药物选择压力。
