Institute of Antibiotics, Huashan Hospital, Fudan University, Shanghai, People's Republic of China.
Key Laboratory of Clinical Pharmacology of Antibiotics, Ministry of Health, Shanghai, People's Republic of China.
Microbiol Spectr. 2023 Jun 15;11(3):e0308022. doi: 10.1128/spectrum.03080-22. Epub 2023 Apr 18.
The rapid acquisition of antibiotic resistance of Pseudomonas aeruginosa has been a complex problem in clinics. Two meropenem-resistant P. aeruginosa isolates were collected from the same patient on May 24, 2021, and June 4, 2021, respectively. The first was susceptible to aztreonam, while the second displayed resistance. This study aimed to identify the genetic differences between two P. aeruginosa isolates and uncover alterations formed by the within-host bacterial evolution leading to aztreonam resistance during therapy. Strains were subjected to antimicrobial susceptibility testing using the broth microdilution method. Genomic DNAs were obtained to identify their genetic differences. The relative mRNA levels of β-lactam-resistance genes were determined by real-time PCR. Both isolates belonged to ST 773 high-risk clones with the same antibiotic resistance genes, eliminating the possibility of horizontally obtaining resistance genes. Reverse transcription (RT)-PCR results showed that the mRNA level in the second one was about 1,500 times higher than that in the first one. When 3-aminophenyl boronic acid was added, the second strain recovered its susceptibility to aztreonam, which confirmed that the overexpression of was the main reason for the isolate's resistance to aztreonam. Compared to the first strain, the second showed a single amino acid substitution in AmpR located upstream of , which may contribute to the upregulation of and lead to aztreonam resistance. plays an essential role in regulating antibiotic resistance in P. aeruginosa, and there is a need to be alert to clinical treatment failures associated with mutations in . Pseudomonas aeruginosa is notorious for being highly resistant to antimicrobial agents. In this study, two P. aeruginosa strains isolated from the same patient with different susceptibility to aztreonam were used to illustrate the within-host resistance evolution process of P. aeruginosa. Both isolates, which belonged to a ST773 high-risk clone, had the same β-lactam resistance genes (, , , and ), which means the second isolate might have been derived from the first isolate by gaining aztreonam resistance via mutations associated with aztreonam resistance relative genes. Subsequently, we found that mutation in may be the cause of aztreonam resistance in the second isolate. Mutation in leads to its loss of control over , allowing overexpression of and further resistance to aztreonam. This study revealed that plays an essential role in regulating antibiotic resistance in P. aeruginosa. There is a need to be alert to clinical treatment failures associated with mutations in .
铜绿假单胞菌对抗生素耐药性的快速获得一直是临床中的一个复杂问题。2021 年 5 月 24 日和 6 月 4 日，分别从同一位患者中采集到 2 株耐美罗培南的铜绿假单胞菌分离株。第 1 株对氨曲南敏感，而第 2 株则表现出耐药性。本研究旨在鉴定两株铜绿假单胞菌分离株的遗传差异，并揭示在治疗过程中，细菌在宿主内进化导致对氨曲南耐药的改变。采用肉汤微量稀释法进行抗菌药物敏感性试验，以鉴定菌株的遗传差异。用实时 PCR 法测定β-内酰胺类耐药基因的相对 mRNA 水平。两株菌均属于 ST773 高危克隆，具有相同的抗生素耐药基因，排除了水平获得耐药基因的可能性。逆转录（RT）-PCR 结果显示，第 2 株菌的 mRNA 水平约为第 1 株菌的 1500 倍。当加入 3-氨基苯硼酸后，第 2 株菌恢复对氨曲南的敏感性，证实 过表达是导致该分离株对氨曲南耐药的主要原因。与第 1 株菌相比，第 2 株菌在 AmpR 上游的位置发生了单个氨基酸替换，这可能导致 上调，从而导致对氨曲南耐药。在铜绿假单胞菌中， 对于调节抗生素耐药性起着至关重要的作用，需要警惕与 基因突变相关的临床治疗失败。铜绿假单胞菌对抗生素的耐药性极强。本研究以两株来自同一患者、对氨曲南敏感性不同的铜绿假单胞菌为例，阐述了铜绿假单胞菌在宿主内的耐药进化过程。两株菌均属于 ST773 高危克隆，具有相同的β-内酰胺类耐药基因（ 、 、 、 ），这意味着第 2 株菌可能是由第 1 株菌通过获得与氨曲南耐药相关的基因发生突变而获得对氨曲南的耐药性。随后，我们发现突变可能是第 2 株菌对氨曲南耐药的原因。突变导致其对 失去控制，使 过度表达，从而进一步对氨曲南产生耐药性。本研究表明 在铜绿假单胞菌中调节抗生素耐药性起着至关重要的作用。需要警惕与 基因突变相关的临床治疗失败。
