Yang Ye, Zhang Hui, Zhao Rongqing, Qiu Xuedan, Ye Jinglu, Lu Wenjun, Li Qingcao, Wu Guangliang
Department of Clinical Laboratory, The Affiliated LiHuiLi Hospital of Ningbo University, Ningbo, China.
Department of Clinical Laboratory, Ninghai County Chengguan Hospital, Ningbo, China.
Front Microbiol. 2024 Oct 18;15:1459162. doi: 10.3389/fmicb.2024.1459162. eCollection 2024.
is an emerging nosocomial opportunistic pathogen with increasing multidrug resistance. Antibiotic resistance, driven primarily by the horizontal transfer of resistance genes, has become a global health crisis. Integrons, mobile genetic elements, are now understood to facilitate the transfer of these genes, contributing to the rapid proliferation of resistant strains. Understanding the regulatory role of integrons in drug resistance gene expression is crucial for developing novel strategies to combat this pressing public health issue.
To investigate the distribution of promoter types in the variable regions of class 1 integrons isolated from clinical isolates of and their regulatory role in the expression of downstream drug resistance gene cassettes.
Ninety seven clinical isolates of were screened for the presence of class 1 integrons () using polymerase chain reaction (PCR). Gene cassettes within the variable regions of positive isolates were characterized, and the gene cassette promoter Pc variants and downstream auxiliary promoter P2 were identified. Enterobacterial repetitive intergenic consensus (ERIC)-PCR was employed for homology analysis. Recombinant plasmids containing different variable region promoters and gene cassettes were constructed to evaluate drug resistance genes and integrase () expression levels using reverse transcription-quantitative PCR (RT-qPCR) and antimicrobial susceptibility testing.
Of the clinical isolates, 28.9% ( = 28/97) were positive for class 1 integrons. 24.7% ( = 24/97) of these isolates carried gene cassettes encoding resistance to aminoglycosides and trimethoprim. Three Pc promoter types (PcH1, PcS, and PcW) were identified, while all P2 promoters were inactive with a 14-base pair spacing between the -35 and -10 regions. ERIC-PCR analysis classified the integron-positive strains into 6 genotypes, with high consistency in promoter types and gene cassettes within each genotype. RT-qPCR and antimicrobial susceptibility testing demonstrated that strong promoters significantly enhanced the expression of downstream drug resistance gene cassettes compared to weak promoters. Additionally, RT-qPCR revealed a negative correlation between expression and Pc promoter strength.
Class 1 integrons are prevalent in . The promoter types within these integrons are diverse, and promoter strength is closely linked to downstream gene cassette expression. Integron-positive strains exhibit high homology, suggesting horizontal gene transfer and dissemination in clinical settings.
是一种新兴的医院内机会性病原体，多重耐药性不断增加。主要由耐药基因水平转移驱动的抗生素耐药性已成为全球卫生危机。整合子作为可移动遗传元件，现在被认为有助于这些基因的转移，促进耐药菌株的快速增殖。了解整合子在耐药基因表达中的调控作用对于制定应对这一紧迫公共卫生问题的新策略至关重要。
研究从临床分离株中分离出的1类整合子可变区启动子类型的分布及其对下游耐药基因盒表达的调控作用。
采用聚合酶链反应（PCR）对97株临床分离株进行1类整合子（）检测。对阳性分离株可变区内的基因盒进行鉴定，确定基因盒启动子Pc变体和下游辅助启动子P2。采用肠杆菌重复基因间共有序列（ERIC）-PCR进行同源性分析。构建含有不同可变区启动子和基因盒的重组质粒，利用逆转录定量PCR（RT-qPCR）和药敏试验评估耐药基因和整合酶（）表达水平。
在临床分离株中，28.9%（=28/97）的1类整合子呈阳性。其中24.7%（=24/97）的分离株携带编码对氨基糖苷类和甲氧苄啶耐药的基因盒。鉴定出3种Pc启动子类型（PcH1、PcS和PcW），而所有P2启动子均无活性，-35区和-10区之间有14个碱基对的间隔。ERIC-PCR分析将整合子阳性菌株分为6种基因型，每种基因型内启动子类型和基因盒具有高度一致性。RT-qPCR和药敏试验表明，与弱启动子相比，强启动子显著增强了下游耐药基因盒的表达。此外，RT-qPCR显示表达与Pc启动子强度呈负相关。
1类整合子在中普遍存在。这些整合子内的启动子类型多样，启动子强度与下游基因盒表达密切相关。整合子阳性菌株表现出高度同源性，提示在临床环境中存在水平基因转移和传播。
