Department of Clinical Laboratory, First Affiliated Hospital of Kunming Medical University, Kunming, 650032, China.
Yunnan Key Laboratory of Laboratory Medicine, Kunming, 650032, China.
Braz J Microbiol. 2023 Jun;54(2):655-664. doi: 10.1007/s42770-023-00933-3. Epub 2023 Mar 17.
Infection with P. aeruginosa, one of the most relevant opportunistic pathogens in hospital-acquired infections, can lead to high mortality due to its low antibiotic susceptibility to limited choices of antibiotics. Polymyxin as last-resort antibiotics is used in the treatment of systemic infections caused by multidrug-resistant P. aeruginosa strains, so studying the emergence of polymyxin-resistant was a must. The present study was designed to define genomic differences between paired polymyxin-susceptible and polymyxin-resistant P. aeruginosa strains and established polymyxin resistance mechanisms, and common chromosomal mutations that may confer polymyxin resistance were characterized. A total of 116 CRPA clinical isolates from patients were collected from three tertiary care hospitals in China during 2017-2021. Our study found that polymyxin B resistance represented 3.45% of the isolated carbapenem-resistant P. aeruginosa (CRPA). No polymyxin-resistant isolates were positive for mcr (1-8 and 10) gene and efflux mechanisms. Key genetic variations identified in polymyxin-resistant isolates involved missense mutations in parR, parS, pmrB, pmrA, and phoP. The waaL and PA5005 substitutions related to LPS synthesis were detected in the highest levels of resistant strain (R1). The missense mutations H398R in ParS (4/4), Y345H in PmrB (4/4), and L71R in PmrA (3/4) were the predominant. Results of the PCR further confirmed that mutation of pmrA, pmrB, and phoP individually or simultaneously did affect the expression level of resistant populations and can directly increase the expression of arnBCADTEF operon to contribute to polymyxin resistance. In addition, we reported 3 novel mutations in PA1945 (2129872_A < G, 2130270_A < C, 2130272_T < G) that may confer polymyxin resistance in P. aeruginosa. Our findings enriched the spectrum of chromosomal mutations, highlighted the complexity at the molecular level, and multifaceted interplay mechanisms underlying polymyxin resistance in P. aeruginosa.
铜绿假单胞菌是医院获得性感染中最重要的机会性病原体之一，由于其对有限选择的抗生素的低抗生素敏感性，感染可导致高死亡率。多粘菌素作为最后手段的抗生素，用于治疗多药耐药铜绿假单胞菌引起的全身感染，因此研究多粘菌素耐药性的出现是必须的。本研究旨在定义配对的多粘菌素敏感和多粘菌素耐药铜绿假单胞菌菌株之间的基因组差异，并建立多粘菌素耐药机制，并对可能赋予多粘菌素耐药性的常见染色体突变进行特征描述。2017 年至 2021 年期间，从中国的三家三级医院共收集了 116 例耐碳青霉烯铜绿假单胞菌（CRPA）的临床分离株。我们的研究发现，多粘菌素 B 耐药代表分离出的耐碳青霉烯铜绿假单胞菌（CRPA）的 3.45%。没有多粘菌素耐药分离株对 mcr（1-8 和 10）基因和外排机制呈阳性。在多粘菌素耐药分离株中鉴定出的关键遗传变异涉及 parR、parS、pmrB、pmrA 和 phoP 中的错义突变。在耐药株（R1）中检测到与 LPS 合成相关的 waaL 和 PA5005 取代物的最高水平。parS 中的 H398R 错义突变（4/4）、pmrB 中的 Y345H 错义突变（4/4）和 pmrA 中的 L71R 错义突变（3/4）是主要的。PCR 结果进一步证实，pmrA、pmrB 和 phoP 的突变单独或同时影响耐药群体的表达水平，并直接增加 arnBCADTEF 操纵子的表达，有助于多粘菌素耐药。此外，我们报告了 3 个新的突变在 PA1945（2129872_A < G，2130270_A < C，2130272_T < G）可能导致铜绿假单胞菌的多粘菌素耐药。我们的发现丰富了染色体突变谱，突出了分子水平的复杂性以及铜绿假单胞菌多粘菌素耐药性的多方面相互作用机制。
