Liu Mi, Liu Jing, Ma Jie, Li Wanxiang, Zhao Xue, Jia Wei, Li Shirong
Clinical Laboratory of Weifang People's Hospital, 151 Guangwen Street, Weifang, Shandong Province, 261041, China.
Microb Pathog. 2022 Sep;170:105669. doi: 10.1016/j.micpath.2022.105669. Epub 2022 Jul 6.
To investigate the distribution of class 1 integrons and their variable regional molecular characteristics, as well as the diversity of promoter and drug sensitivity of CR-Eco (carbapenem-resistant E. coli) strains.
A total of 117 CR-Eco strains, collected between 2012.01 and 2019.12, underwent fully automated bacterial identification and sensitization using VITEK-2 Compact and supplemented by K-B assay. PCR was employed to screen for class 1 integrase genes and integron variable regions, while the promoter type and variable region gene cassette characteristics were determined by sequencing analysis.
The positive rate of the class 1 integron of the CR-Eco strains was 83.70% (92/117) herein. Moreover, class 1 integrase-positive strains exhibited statistically significant resistance to aztreonam, ceftazidime, ciprofloxacin, ceftriaxone, gentamicin, meropenem, and trimethoprim-sulfamethoxazole compared to integron-negative strains (P < 0.05). Variable regions were observed in 77 of the 92 class 1 integrase-positive strains. In addition, seven gene cassettes were detected, namely dfrA17-aadA5, aadA22, dfrA12-aadA2, dfrA12, dfrA17, dfrA27 and aadA. Finally, five types of class 1 integron variable region promoters were identified in those 77 strains, including PcW, PcH1, PcW, PcH1, and P2, which were detected in 48, 18, 8, 2, and 1 strains, respectively.
The primary integrator variable region gene cassettes of this class were dfrA and aadA. The integron-positive strains displayed simultaneous high resistance to multiple antimicrobial drugs. The integrator variable region promoters of the CR-Eco strains are primarily weak and can potentially form and spread drug resistance.
研究1类整合子的分布及其可变区分子特征，以及耐碳青霉烯类大肠埃希菌（CR-Eco）菌株启动子的多样性和药敏情况。
收集2012年1月至2019年12月期间的117株CR-Eco菌株，使用VITEK-2 Compact进行全自动细菌鉴定和药敏试验，并以K-B法作为补充。采用PCR技术筛选1类整合酶基因和整合子可变区，通过测序分析确定启动子类型和可变区基因盒特征。
本研究中CR-Eco菌株1类整合子的阳性率为83.70%（92/117）。此外，与整合子阴性菌株相比，1类整合酶阳性菌株对氨曲南、头孢他啶、环丙沙星、头孢曲松、庆大霉素、美罗培南和复方磺胺甲恶唑表现出统计学上的显著耐药性（P < 0.05）。在92株1类整合酶阳性菌株中的77株中观察到可变区。此外，检测到7种基因盒，即dfrA17-aadA5、aadA22、dfrA12-aadA2、dfrA12、dfrA17、dfrA27和aadA。最后，在这77株菌株中鉴定出5种1类整合子可变区启动子，包括PcW、PcH1、PcW、PcH1和P2，分别在48、18、8、2和1株中检测到。
此类主要的整合子可变区基因盒为dfrA和aadA。整合子阳性菌株对多种抗菌药物同时表现出高耐药性。CR-Eco菌株的整合子可变区启动子主要为弱启动子，可能会形成并传播耐药性。
