Central Laboratory, Peking University School and Hospital of Stomatology & National Engineering Laboratory for Digital and Material Technology of Stomatology & Beijing Key Laboratory of Digital Stomatology, Beijing, People's Republic of China.
Antimicrob Resist Infect Control. 2019 Feb 4;8:27. doi: 10.1186/s13756-019-0483-9. eCollection 2019.
Antibiotic resistance, is often conferred by the presence of antibiotic resistance genes. This study aimed to investigate the relationship between tetracycline resistance (Tet-R) and genotype in 31 isolates from caries-active patients.
The tetracycline susceptibility of isolates was determined using the agar spot test and the genetic characteristics associated with tetracycline resistance using whole-genome sequencing (WGS).
The minimum inhibitory concentration (MIC) values of most isolates were equal to or lower than the breakpoint MIC values. Four strains that were phenotypically more sensitive ( B09, S23 and B17) or more resistant ( B43) than other isolates to tetracycline were subjected to conduct whole-genome sequencing in order to detect the tetracycline resistance genes. The results revealed that the most common Tet-R genes in strains were T, W, O and L. In addition, PB, 3 and A were detected for the first time. There were distinct Tet-R gene mutations in isolates. Overall, the mean expression values of Tet-R-mutated genes in B43 were elevated, and the relative expression levels of T and W genes in B17 B09 and S23 were decreased relative to reference strains.
The results of this study indicate that isolates from saliva of caries-active patients do not present considerable tetracycline resistance reservoirs. However, genetic compounds associated with tetracycline resistance were identified by whole-genome sequencing, providing meaningful insights into tetracycline resistance mechanisms.
抗生素耐药性通常由抗生素耐药基因的存在引起。本研究旨在调查 31 株来自龋齿活跃患者的分离株中四环素耐药（Tet-R）与基因型的关系。
使用琼脂斑点试验测定分离株的四环素药敏性，并使用全基因组测序（WGS）检测与四环素耐药相关的遗传特征。
大多数分离株的最小抑菌浓度（MIC）值等于或低于断点 MIC 值。对 4 株比其他分离株对四环素更敏感（B09、S23 和 B17）或更耐药（B43）的分离株进行全基因组测序，以检测四环素耐药基因。结果表明，菌株中最常见的 Tet-R 基因是 T、W、O 和 L。此外，首次检测到 PB、3 和 A。分离株中存在明显的 Tet-R 基因突变。总体而言，B43 中 Tet-R 基因突变基因的表达值升高，而 B17、B09 和 S23 中 T 和 W 基因的相对表达水平相对于参考菌株降低。
本研究结果表明，来自龋齿活跃患者唾液的分离株没有表现出相当大的四环素耐药库。然而，通过全基因组测序鉴定了与四环素耐药相关的遗传化合物，为四环素耐药机制提供了有意义的见解。
