Ramazanzadeh Rashid, Mohammadi Bahman, Mohajeri Parviz
Cellular & Molecular Research Center, Kurdistan University of Medical Sciences, Sanandaj, Iran; Department of Microbiology, Kurdistan University of Medical Sciences, Sanandaj, Iran.
Department of Microbiology, Kurdistan University of Medical Sciences, Sanandaj, Iran; Student Research Committee, Kurdistan University of Medical Sciences, Sanandaj, Iran; Department of Microbiology, Kurdistan University of Medical Sciences, Sanandaj, Iran.
Int J Mycobacteriol. 2016 Dec;5 Suppl 1:S140. doi: 10.1016/j.ijmyco.2016.11.013. Epub 2016 Nov 24.
Mutations in embB gene, especially those in ethambutol resistance-determining region (ERDR), are known as "hot spots". These mutations have frequently been reported in EMB-resistant M. tuberculosis isolates, using the Sequence analysis as a precise and effective method. The aim of this study was to detect mutations in embB gene associated with resistance to ethambutol in Mycobacterium tuberculosis strains isolated from TB patients in the west of Iran (2014-15).
This study was performed on smear-positive patients of the west side of Iran, in the TB research center located in Kermanshah city, during 2014-15. Out of 1069 strains of Mycobacterium tuberculosis, 50 strains with pulmonary TB were selected and evaluated (22 men and 28 women; aged between 23 and 86; median age: 54.5years).
Mutation in the embB gene was detected in all of the seven EMB-resistance isolates and five (42.71%) cases of them were MDR. The most frequent substantiation of amino acid occurred at the codon 306 in six (64.85%) of the EMB-resistant isolates. The Met306Val substitution resulting from an A→G transition was detected in three (42.85%) EMB-resistant isolates; and the Met306Ile substitution, due to a G→A transition was also detected in three (42.85%) resistant isolates. No mutations at the embB gene were detected in susceptible strains.
Our results were similar to those that were regularly reported in earlier studies. The only mutations in the EMB-resistant isolates were found in embB 306 and 406 codons. Substantiation amino acids at codon 306 were the most frequent. The data indicated that embB 306 mutations are sufficient to induce ethambutol resistance, and detection of these mutations is advisable to be considered in the development of rapid molecular tests. Sequence analysis of the ERDR in the embB gene is adequate for rapid detection of EMB resistance, and mutations in the codon 306 are good predictive markers for resistance to EMB.
embB基因的突变，尤其是那些位于乙胺丁醇耐药决定区（ERDR）的突变，被称为“热点”。使用序列分析作为一种精确有效的方法，这些突变在耐乙胺丁醇的结核分枝杆菌分离株中经常被报道。本研究的目的是检测从伊朗西部的结核病患者中分离出的结核分枝杆菌菌株中与乙胺丁醇耐药相关的embB基因突变（2014 - 15年）。
本研究于2014 - 15年在位于克尔曼沙赫市的结核病研究中心，对伊朗西部涂片阳性患者进行。在1069株结核分枝杆菌中，选择并评估了50株肺结核菌株（22名男性和28名女性；年龄在23至86岁之间；中位年龄：54.5岁）。
在所有7株耐乙胺丁醇分离株中均检测到embB基因突变，其中5株（42.71%）为耐多药菌株。在6株（64.85%）耐乙胺丁醇分离株中，氨基酸最常见的证实发生在密码子306处。在3株（42.85%）耐乙胺丁醇分离株中检测到由A→G转换导致的Met306Val替代；并且在3株（42.85%）耐药分离株中也检测到由于G→A转换导致的Met306Ile替代。在敏感菌株中未检测到embB基因突变。
我们的结果与早期研究中经常报道的结果相似。在耐乙胺丁醇分离株中仅在embB 306和406密码子中发现突变。密码子306处的证实氨基酸最为常见。数据表明embB 306突变足以诱导乙胺丁醇耐药，并且在快速分子检测的开发中建议考虑检测这些突变。对embB基因中的ERDR进行序列分析足以快速检测乙胺丁醇耐药，并且密码子306中的突变是乙胺丁醇耐药的良好预测标志物。
