ABSTRACT

Pseudomonas aeruginosa has different antibiotic resistance pathways, such as broad-spectrum lactamases and metallo-β-lactamases (MBL), penicillin-binding protein (PBP) alteration, and active efflux pumps. Polymerase chain reaction (PCR) and sequencing methods were applied for double-locus sequence typing (DLST) and New Delhi metallo-β-lactamase (NDM) typing. We deduced the evolutionary pathways for DLST and NDM genes of P. aeruginosa using phylogenetic network. Among the analyzed isolates, 62.50% of the P. aeruginosa isolates were phenotypically carbapenem resistance (CARBR) isolates. Characterization of isolates revealed that the prevalence of bla_NDM, bla_VIM, bla_IMP, undetermined carbapenemase, and MexAB-OprM were 27.5%, 2%, 2.5%, 12.5%, and 15%, respectively. The three largest clusters found were DLST t20–105, DLST t32–39, and DLST t32–52. The network phylogenic tree revealed that DLST t26–46 was a hypothetical ancestor for other DLSTs, and NDM-1 was as a hypothetical ancestor for NDMs. The combination of the NDM and DLST phylogenic trees revealed that DLST t32–39 and DLST tN2-N3 with NDM-4 potentially derived from DLST t26–46 along with NDM-1. Similarly, DLST t5–91 with NDM-5 diversified from DLST tN2-N3 with NDM-4. This is the first study in which DLST and NDM evolutionary routes were performed to investigate the origin of P. aeruginosa isolates. Our study showed that the utilization of medical equipment common to two centers, staff members common to two centers, limitations in treatment options, and prescription of unnecessary high levels of meropenem are the main agents that generate new types of resistant bacteria and spread resistance among hospitals.

摘要

铜绿假单胞菌具有不同的抗生素耐药途径，例如广谱内酰胺酶和金属-β-内酰胺酶（MBL）、青霉素结合蛋白（PBP）改变和主动外排泵。应用聚合酶链式反应（PCR）和测序方法进行双基因座序列分型（DLST）和新德里金属-β-内酰胺酶（NDM）分型。我们利用系统发育网络推导了铜绿假单胞菌DLST和NDM基因的进化途径。在分析的分离株中，62.50%的铜绿假单胞菌分离株是表型碳青霉烯类耐药（CARBR）分离株。分离株的特征显示，bla _NDM、bla _VIM、bla _IMP、未确定的碳青霉烯酶和 MexAB-OprM 的患病率分别为 27.5%、2%、2.5%、12.5% 和 15%。发现的三个最大簇是 DLST t20-105、DLST t32-39 和 DLST t32-52。网络系统发育树显示DLST t26-46是其他DLST的假设祖先，NDM-1是NDM的假设祖先。NDM 和 DLST 系统发育树的组合表明，DLST t32-39 和 DLST tN2-N3 与 NDM-4 可能源自 DLST t26-46 以及 NDM-1。同样，带有 NDM-5 的 DLST t5-91 从带有 NDM-4 的 DLST tN2-N3 多样化。这是第一项通过 DLST 和 NDM 进化路线来研究铜绿假单胞菌分离株起源的研究。我们的研究表明，使用两个中心共用的医疗设备、两个中心共用的工作人员、治疗方案的限制以及不必要的高浓度美罗培南处方是产生新型耐药菌并在医院之间传播耐药性的主要因素。