Arredondo Alexandre, Àlvarez Gerard, Nart José, Mor Carolina, Blanc Vanessa, León Rubén
Department of Microbiology, Dentaid Research Center, Cerdanyola del Vallès, Spain.
Departament de Genètica i Microbiologia, Universitat Autònoma de Barcelona, Bellaterra, Spain.
J Oral Microbiol. 2019 Jul 23;11(1):1643204. doi: 10.1080/20002297.2019.1643204. eCollection 2019.
Tetracycline resistance can be achieved through genes, which code for efflux pumps, ribosomal protection proteins and inactivation enzymes. Some of these genes have only been described in either Gram-positive or Gram-negative bacteria. This is the case of (B), which codes for an efflux pump and, so far, had only been found in Gram-negative bacteria. In this study, (B) was detected in two clinical strains isolated from the gingival sulci of two subjects. In both cases, the gene was completely sequenced, yielding 100% shared identity and coverage with other previously published sequences of (B). Moreover, we studied the expression of (B) using RT-qPCR in the isolates grown with and without tetracycline, detecting constitutive expression in only one of the isolates, with no signs of expression in the other one. This is the first time that the presence and expression of the (B) gene has been confirmed in Gram-positive bacteria, which highlights the potential of the genus to become a reservoir and a disseminator of antibiotic resistance genes in an environment so prone to horizontal gene transfer as is the oral biofilm.
四环素抗性可通过编码外排泵、核糖体保护蛋白和灭活酶的基因来实现。其中一些基因仅在革兰氏阳性菌或革兰氏阴性菌中被描述过。（B）就是这样的情况，它编码一种外排泵，到目前为止，仅在革兰氏阴性菌中被发现。在本研究中，在从两名受试者牙龈沟分离出的两株临床菌株中检测到了（B）。在这两种情况下，该基因都被完全测序，与其他先前发表的（B）序列具有100%的共享同一性和覆盖率。此外，我们使用RT-qPCR研究了在添加和不添加四环素的情况下培养的分离株中（B）的表达，仅在其中一株分离株中检测到组成型表达，另一株没有表达迹象。这是首次在革兰氏阳性菌中证实（B）基因的存在和表达，这突出了该属在如此易于水平基因转移的口腔生物膜环境中成为抗生素抗性基因储存库和传播者的潜力。
