Department of Laboratory Medicine, The Affiliated Hospital of Southwest Medical University, Luzhou, China; Sichuan Province Engineering Technology Research Center of Molecular Diagnosis of Clinical Diseases, Luzhou, China; Molecular Diagnosis of Clinical Diseases Key Laboratory of Luzhou, China.
Microb Pathog. 2024 Jul;192:106668. doi: 10.1016/j.micpath.2024.106668. Epub 2024 Apr 30.
The emergence of carbapenem-resistant Pseudomonas putida (CRPP) has raised public awareness. This study investigated two strains from the Pseudomonas putida group that were resistant to carbapenem, tigecycline, and aztreonam-avibactam (ATM-AVI), with a focus on their microbial and genomic characteristics.
We assessed the antibiotic resistance profile using broth dilution, disk diffusion, and E-test methods. Efflux pump phenotype testing and real-time quantitative PCR were employed to evaluate efflux pump activity in tigecycline resistance, while polymerase chain reaction was utilized to detect common carbapenem genes. Additionally, whole-genome sequencing was performed to analyze genomic characteristics. The transferability of bla and bla was assessed through a conjugation experiment. Furthermore, growth kinetics and biofilm formation were examined using growth curves and crystal violet staining.
Both strains demonstrated resistance to carbapenem, tigecycline, and ATM-AVI. Notably, NMP can restore sensitivity to tigecycline. Subsequent analysis revealed that they co-produced bla, bla, tmexCD-toprJ, and bla, belonging to a novel sequence type ST268. Although they were closely related on the phylogenetic tree, they exhibited different levels of virulence. Genetic environment analysis indicated variations compared to prior studies, particularly regarding the bla and bla genes, which showed limited horizontal transferability. Moreover, it was observed that temperature exerted a specific influence on their biological factors.
We initially identified two P. putida ST268 strains co-producing bla, bla, bla, and tmexCD-toprJ. The resistance to tigecycline and ATM-AVI can be attributed to the presence of multiple drug resistance determinants. These findings underscore the significance of P. putida as a reservoir for novel antibiotic resistance genes. Therefore, it is imperative to develop alternative antibiotic therapies and establish effective monitoring of bacterial resistance.
耐碳青霉烯类铜绿假单胞菌（CRPP）的出现引起了公众的关注。本研究调查了两株对碳青霉烯类、替加环素和头孢他啶-阿维巴坦（ATM-AVI）耐药的铜绿假单胞菌属菌株，重点研究了它们的微生物和基因组特征。
我们使用肉汤稀释法、纸片扩散法和 E 试验法评估抗生素耐药谱。采用外排泵表型试验和实时定量 PCR 评估替加环素耐药中外排泵的活性，并用聚合酶链反应检测常见碳青霉烯类基因。此外，还进行了全基因组测序以分析基因组特征。通过接合实验评估 bla 和 bla 的可转移性。还通过生长曲线和结晶紫染色检测生长动力学和生物膜形成。
两株菌均对碳青霉烯类、替加环素和 ATM-AVI 耐药。值得注意的是，NMP 可以恢复对替加环素的敏感性。随后的分析表明，它们共同产生 bla、bla、tmexCD-toprJ 和 bla，属于一个新的序列型 ST268。尽管它们在系统发育树上密切相关，但它们的毒力水平不同。遗传环境分析表明与先前的研究相比存在差异，特别是 bla 和 bla 基因，其水平转移能力有限。此外，还观察到温度对它们的生物学因素有特定的影响。
我们首次鉴定了两株产 bla、bla、bla 和 tmexCD-toprJ 的铜绿假单胞菌 ST268 株。对替加环素和 ATM-AVI 的耐药性可归因于多种耐药决定因素的存在。这些发现强调了铜绿假单胞菌作为新型抗生素耐药基因库的重要性。因此，必须开发替代抗生素治疗方法并建立有效的细菌耐药监测。
