Lu Wenjun, Qiu Quedan, Chen Keda, Zhao Rongqing, Li Qingcao, Wu Qiaoping
Intensive Care Units of Ningbo Medical Centre Lihuili Hospital, Ningbo University, Ningbo, Zhejiang Province, People's Republic of China.
Clinical Laboratory of Ningbo Medical Centre Lihuili Hospital, Ningbo University, Ningbo, Zhejiang Province, People's Republic of China.
Infect Drug Resist. 2022 Feb 16;15:465-474. doi: 10.2147/IDR.S347119. eCollection 2022.
Integrons are the main mode of horizontal transmission of drug-resistance genes and are closely related to drug resistance in clinical bacteria. In this study, the distributions of class 1, 2, and 3 integron gene cassettes were investigated in 150 () isolates from patients, and molecular characterization of functional class 2 integrons was further analyzed.
Class 1, 2, and 3 integrons were screened by polymerase chain reaction (PCR) in 150 clinical isolates. The variable regions of the integrons were determined by restriction analysis and sequencing. Internal stop codons mutations in class 2 integrons and their common promoters were also determined by sequencing. Enterobacterial repetitive intergenic consensus polymerase chain reaction (ERIC-PCR) was used to analyze the phylogenetic relations of class 2 integron-positive isolates.
Class 1 integrons were detected in 69 (46%) of 150 isolates, and six different gene cassette arrays were detected, with the most prevalent being . Class 2 integrons were detected in 61 (40.7%) of 150 isolates, and three different gene cassette arrays were detected, including , which was detected for the first time in a class 2 integron. Nearly similar ERIC-PCR fingerprinting patterns were detected in 45 (73.8%) of 61 class 2 integron-positive isolates. The functional class 2 integron was detected in three isolates having the same gene cassette, , in the variable region and four novel open reading frames with unknown functions. Same P and Pc promoters were detected in these three functional class 2 integron isolates, as was found in other class 2 integron isolates. However, these three strains did not totally show identical homology and drug sensitivity.
Although functional class 2 integrons have low distribution and relatively conserved molecular characteristics, they can still form clinical dissemination and drug resistance expression.
整合子是耐药基因水平转移的主要方式，与临床细菌的耐药性密切相关。本研究调查了150株临床分离株中1类、2类和3类整合子基因盒的分布情况，并进一步分析了功能性2类整合子的分子特征。
采用聚合酶链反应（PCR）对150株临床分离株进行1类、2类和3类整合子筛选。通过限制性分析和测序确定整合子的可变区。通过测序还确定了2类整合子内部终止密码子突变及其共同启动子。采用肠杆菌重复基因间共有序列聚合酶链反应（ERIC-PCR）分析2类整合子阳性分离株的系统发育关系。
在150株分离株中的69株（46%）检测到1类整合子，共检测到6种不同的基因盒阵列，其中最常见的是 。在150株分离株中的61株（40.7%）检测到2类整合子，共检测到3种不同的基因盒阵列，包括 在2类整合子中首次检测到的 。在61株2类整合子阳性分离株中的45株（73.8%）检测到近乎相似的ERIC-PCR指纹图谱。在3株可变区具有相同基因盒 的分离株中检测到功能性2类整合子，并发现了4个功能未知的新开放阅读框。在这3株功能性2类整合子分离株中检测到与其他2类整合子分离株相同的P和Pc启动子。然而，这3株菌株并未完全表现出相同的同源性和药敏性。
尽管功能性2类整合子分布较少且分子特征相对保守，但仍可形成临床传播和耐药表达。
