背景:这项研究旨在表征从1997年至2015年菌血症患者中分离出的碳青霉烯类不敏感不动杆菌(CNSA)。
方法:从1403株不动杆菌中回收到173株CNSA(12.3%)。通过PCR扩增确定在CNSA中选择的β-内酰胺酶基因的存在。结合试验用于确定携带金属-β-内酰胺酶(MBL)的质粒的可转移性。结合表型测定进行全基因组测序以表征MBL-质粒。
结果:一般来说,观察到CNSA数量增加的趋势。在173个CNSA中,鲍曼不动杆菌(54.9%)是最常见的物种,其次是A.counternoialis(23.1%)和A.soli(12.1%)。共有49例(28.3%)CNSA广泛耐药,都是A.Baumannii.173个CNSA中最常见的D类碳青霉烯酶基因是blaOXA-24样基因(32.4%),其次是ISAba1-blaOXA-51-like(20.8%),ISAba1-blaOXA-23(20.2%),和IS1006/IS1008-blaOXA-58(11.6%)。MBL基因,blaVIM-11,blaIMP-1和blaIMP-19在9(5.2%)中检测到,20(11.6%),和1个(0.6%)CNSA分离株,分别。在30个MBL质粒中,有7个和6个成功将MBL基因转移到AB218和AN254受体细胞中,分别。携带MBL质粒的7个AB218衍生的转结合体产生的生物膜较少,但对幼虫的毒力高于受体AB218。
结论:我们19年的纵向研究显示,在2005-2015年期间,CNSA呈稳定增长。像blaOXA-24一样,ISAba1-blaOXA-51-like,ISAba1-blaOXA-23是碳青霉烯类不动杆菌耐药性的主要决定因素。携带MBL的质粒不仅有助于碳青霉烯抗性,而且有助于鲍曼不动杆菌的毒力。
BACKGROUND: This study aimed to characterize carbapenem-nonsusceptible Acinetobacter (CNSA) isolated from patients with bacteremia from 1997 to 2015.
METHODS: A total of 173 CNSA (12.3%) was recovered from 1403 Acinetobacter isolates. The presence of selected β-lactamase genes in CNSA was determined by PCR amplification. The conjugation test was used to determine the transferability of metallo-β-lactamase (MBL)-carrying plasmids. Whole genome sequencing in combination with phenotypic assays was carried out to characterize MBL-plasmids.
RESULTS: In general, a trend of increasing numbers of CNSA was observed. Among the 173 CNSA, A. baumannii (54.9%) was the most common species, followed by A. nosocomialis (23.1%) and A. soli (12.1%). A total of 49 (28.3%) CNSA were extensively drug-resistant, and all were A. baumannii. The most common class D carbapenemase gene in 173 CNSA was blaOXA-24-like (32.4%), followed by ISAba1-blaOXA-51-like (20.8%), ISAba1-blaOXA-23 (20.2%), and IS1006/IS1008-blaOXA-58 (11.6%). MBL genes, blaVIM-11,blaIMP-1, and blaIMP-19 were detected in 9 (5.2%), 20 (11.6%), and 1 (0.6%) CNSA isolates, respectively. Transfer of MBL genes to AB218 and AN254 recipient cells was successful for 7 and 6 of the 30 MBL-plasmids, respectively. The seven AB218-derived transconjugants carrying MBL-plasmids produced less biofilm but showed higher virulence to larvae than recipient AB218.
CONCLUSIONS: Our 19-year longitudinal study revealed a stable increase in CNSA during 2005-2015. blaOXA-24-like, ISAba1-blaOXA-51-like, and ISAba1-blaOXA-23 were the major determinants of Acinetobacter carbapenem resistance. MBL-carrying plasmids contribute not only to the carbapenem resistance but also to A. baumannii virulence.