Park Sanghee, Jung Jihee, Kim Jiyeon, Han Sang Bong, Ryoo Sungweon
Clinical Research Center, Masan National Tuberculosis Hospital, Changwon, Republic of Korea.
Department of Laboratory Medicine, Masan National Tuberculosis Hospital, Changwon, Republic of Korea.
Tuberc Respir Dis (Seoul). 2022 Jul;85(3):256-263. doi: 10.4046/trd.2021.0175. Epub 2022 May 19.
Mycobacterium tuberculosis (Mtb) is resistant to the β-lactam antibiotics due to a non-classical transpeptidase in the cell wall with β-lactamase activity. A recent study showed that meropenem combined with a β-lactamase inhibitor clavulanate, was effective in MDR and XDR tuberculosis (TB). However, clavulanate can only be used in drugs containing amoxicillin in Korea. In this study, we investigated the susceptibility and genetic mutations of drug-resistant Mtb isolates to amoxicillin-clavulanate and meropenem-clavulanate to improve the diagnosis and treatment of drug-resistant TB patients.
The minimum inhibitory concentration (MIC) of amoxicillin-clavulanate and meropenem-clavulanate was examined by resazurin microtiter assay. We used 82 MDR and 40 XDR strains isolated in Korea and two reference laboratory strains. Mutations of drug targets blaC, blaI, ldtA, ldtB, dacB2, and crfA were analyzed by PCR and DNA sequencing.
The MIC90 values of amoxicillin and meropenem with clavulanate in drug-resistant Mtb isolates were 64 and 16, respectively. Gene mutations related to amoxicillin/clavulanate and meropenem/clavulanate resistance could not be identified, but T448G mutation of was found in the blaC gene related to β-lactam antibiotics high susceptibility.
Our results provide clinical consideration of β-lactams in treating drug-resistant TB and potential molecular markers of amoxicillin-clavulanate and meropenem-clavulanate susceptibility.
结核分枝杆菌（Mtb）对β-内酰胺类抗生素耐药，这是由于其细胞壁中存在具有β-内酰胺酶活性的非经典转肽酶。最近一项研究表明，美罗培南联合β-内酰胺酶抑制剂克拉维酸对耐多药和广泛耐药结核病（TB）有效。然而，在韩国，克拉维酸仅可用于含阿莫西林的药物中。在本研究中，我们调查了耐药Mtb分离株对阿莫西林-克拉维酸和美罗培南-克拉维酸的敏感性及基因突变情况，以改善耐药结核病患者的诊断和治疗。
采用刃天青微量滴定法检测阿莫西林-克拉维酸和美罗培南-克拉维酸的最低抑菌浓度（MIC）。我们使用了在韩国分离的82株耐多药菌株和40株广泛耐药菌株以及两株参考实验室菌株。通过聚合酶链反应（PCR）和DNA测序分析药物靶点blaC、blaI、ldtA、ldtB、dacB2和crfA的突变情况。
耐药Mtb分离株中，阿莫西林与克拉维酸以及美罗培南与克拉维酸联合使用时的MIC90值分别为64和16。未发现与阿莫西林/克拉维酸和美罗培南/克拉维酸耐药相关的基因突变，但在与β-内酰胺类抗生素高敏感性相关的blaC基因中发现了T448G突变。
我们的结果为β-内酰胺类药物治疗耐药结核病提供了临床参考，并为阿莫西林-克拉维酸和美罗培南-克拉维酸敏感性提供了潜在的分子标志物。
