Oliveira-Pinto Clarisse, Diamantino Cristiane, Oliveira Patrícia L, Reis Mariana P, Costa Patrícia S, Paiva Magna C, Nardi Regina M D, Magalhães Paula P, Chartone-Souza Edmar, Nascimento Andréa M A
Departamento de Biologia Geral, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais; Belo Horizonte, Minas Gerais, Brazil.
Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais; Belo Horizonte, Minas Gerais, Brazil.
J Med Microbiol. 2017 May;66(5):577-583. doi: 10.1099/jmm.0.000468. Epub 2017 May 9.
Class 1 integrons are among the main vehicles that facilitate the spread of antibiotic-resistance genes, with serious public health consequences. The aim of this cross-sectional study was to investigate the presence of class 1 integrons and to characterize their variable regions, as well as the antimicrobial resistance profiles and phylogenetic groups of a collection of Escherichia coli isolates recovered from healthy subjects (n=42) and those with urinary infection (n=40).
The methods used included PCR, sequencing and antimicrobial susceptibility testing.
PCR screening for the integrase gene (intI1) revealed a higher incidence of class 1 integrons in uropathogenic E. coli (65 %, UPEC) than in commensal isolates (11.9 %). Eight of 31 intI1-positive isolates, all of them UPEC, harboured empty integrons. The variable regions of the other 23 contained gene cassettes encoding resistance to β-lactams (blaOXA-1), aminoglycosides (aadA1 and aadA5), trimethoprim (dfrA1 and dfrA17) and an ORF. To our knowledge this is the first report of an ORF identified as a putative phage tail protein associated with a class 1 integron. The aadA1 and dfrA17-addA5 arrays prevailed in commensal E. coli and UPEC, respectively. UPEC isolates were highly resistant to the antimicrobials tested, in contrast to commensal isolates. The E. coli isolates carrying gene cassettes associated with class 1 integrons were found to be unrelated to any phylogroup or multiresistance.
Co-resistance to clinically relevant fluoroquinolone and trimethoprim-sulfamethazole in all UPEC isolates is a cause for concern. These results expand the current knowledge of gene cassettes in both commensal and pathogenic E. coli.
1类整合子是促进抗生素耐药基因传播的主要载体之一，会造成严重的公共卫生后果。这项横断面研究的目的是调查1类整合子的存在情况，对其可变区进行特征分析，同时分析从健康受试者（n = 42）和尿路感染患者（n = 40）中分离出的大肠杆菌菌株的抗菌耐药谱和系统发育群。
使用的方法包括聚合酶链反应（PCR）、测序和抗菌药敏试验。
对整合酶基因（intI1）进行PCR筛查发现，尿路致病性大肠杆菌（UPEC，65%）中1类整合子的发生率高于共生菌株（11.9%）。31株intI1阳性菌株中有8株（均为UPEC）含有空整合子。其他23株的可变区含有编码对β-内酰胺类（blaOXA-1）、氨基糖苷类（aadA1和aadA5）、甲氧苄啶（dfrA1和dfrA17）耐药的基因盒以及一个开放阅读框（ORF）。据我们所知，这是首次报道一个被鉴定为与1类整合子相关的假定噬菌体尾蛋白的ORF。aadA1和dfrA17 - addA5阵列分别在共生大肠杆菌和UPEC中占主导地位。与共生菌株相比，UPEC菌株对所测试的抗菌药物具有高度耐药性。携带与1类整合子相关基因盒的大肠杆菌菌株与任何系统发育群或多重耐药性均无关联。
所有UPEC菌株对临床相关氟喹诺酮类和甲氧苄啶 - 磺胺甲恶唑的共同耐药令人担忧。这些结果扩展了目前对共生和致病性大肠杆菌中基因盒的认识。
