Margaryan Hasmik, Farnia Parissa, Hayrapetyan Armen, Mirzoyan Alvard
Ministry of Health of National Tuberculosis Control Program SNPO, Abovyan, Armenia.
Mycobacteriology Research Center, National Research Institute of Tuberculosis and Lung Diseases, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
Int J Mycobacteriol. 2016 Dec;5 Suppl 1:S159-S160. doi: 10.1016/j.ijmyco.2016.07.010. Epub 2016 Aug 12.
OBJECTIVE/BACKGROUND: The GenoType MTBDRsl test rapidly detects resistance to ethambutol, fluoroquinolones, second-line aminoglycosides (amikacin [AMK] and kanamycin [KAN]), and cyclic peptides (capreomycin [CAP]) in Mycobacterium tuberculosis. According to data from Global Drug Resistance Surveillance Report (2007), Armenia is counted as a high-burden country for multidrug-resistant tuberculosis (MDR-TB). The estimated burden of MDR-TB in 2012 was 9.4 (7-12) and 43 (38-49) among retreatment TB cases. A total of 92 laboratory confirmed cases were reported to the World Health Organization (57 new and 35 previously treated) out of 511 cases tested for MDR-TB.
A set of 77 drug-resistant TB isolates during 2011 and 2012 period, being either acid-fast bacterium positive or negative but culture-positive resistant to isoniazid, rifampin, or both according to the GenoType MTBDR plus assay, were consecutively tested using GenoType MTBDRsl. rrs gene analysis and the results from GenoType MTBDRsl were compared with phenotypic drug resistance testing. The DNA preparation method was performed as recommended by the manufacturer (Genotype MTBDR plus version 1.0 and Genotype MTBDRsl version 2.0 Hain Lifescience Nehren, Germany).
Aminoglycosides are key drugs for the treatment of MDR-TB. A total of 77 drug-resistant TB and four extensively drug-resistant M. tuberculosis isolates from Armenian TB patients were analyzed to characterize mutations within rrs and to compare with phenotypic drug resistance testing. Simultaneously, the following were identified: 65 (84.41%) rrs wild type (WT), 1 (1.3%) rrs WT MUT1 and MUT2 (WT; A1401G and G1484T), 1 (1.3%) rrs WT1, MUT1 (A1401G), 9 (11.7%) rrs WT1, MUT1 (A1401G), and 1 (1.3%) rrs WT1, MUT1. Mutation at position 1401 in rrs leads to resistance to KAN (7/77=9%), AMK (9/77=11.68%), and CAP (5/77=6.49%). Eleven (14.28%) streptomycin-resistant strains had a rrs mutation.
Isolates with rrs structural gene mutations were cross-resistant to streptomycin, KAN, CAP, and AMK. Detection of the A1401G mutation appeared to be 100% specific for the detection of resistance to KAN and AMK. Being the first assessment, these data establish the presence of phenotypic drug-resistant and extensively drug-resistant strains using molecular profiling and are helpful in understanding aminoglycoside resistance on a molecular level.
目的/背景：GenoType MTBDRsl检测可快速检测结核分枝杆菌对乙胺丁醇、氟喹诺酮类、二线氨基糖苷类（阿米卡星[AMK]和卡那霉素[KAN]）以及环肽类（卷曲霉素[CAP]）的耐药性。根据《2007年全球耐药监测报告》的数据，亚美尼亚被列为耐多药结核病（MDR-TB）高负担国家。2012年，复治结核病病例中耐多药结核病的估计负担分别为9.4（7 - 12）和43（38 - 49）。在511例接受耐多药结核病检测的病例中，共有92例实验室确诊病例报告给了世界卫生组织（57例新发病例和35例既往治疗病例）。
在2011年至2012年期间，收集了77株耐药结核病分离株，这些分离株根据GenoType MTBDR plus检测法，要么抗酸菌阳性，要么抗酸菌阴性但培养阳性且对异烟肼、利福平或两者耐药，连续使用GenoType MTBDRsl进行检测。将rrs基因分析结果和GenoType MTBDRsl的结果与表型耐药性检测结果进行比较。DNA制备方法按照制造商的建议进行（德国海因生命科学公司的GenoType MTBDR plus版本1.0和GenoType MTBDRsl版本2.0）。
氨基糖苷类是治疗耐多药结核病的关键药物。对来自亚美尼亚结核病患者的77株耐药结核病分离株和4株广泛耐药结核分枝杆菌分离株进行了分析，以鉴定rrs基因内的突变，并与表型耐药性检测进行比较。同时，鉴定出以下情况：65株（84.41%）rrs野生型（WT），1株（1.3%）rrs WT MUT1和MUT2（WT；A1401G和G1484T），1株（1.3%）rrs WT1，MUT1（A1401G），9株（11.7%）rrs WT1，MUT1（A1401G），以及1株（1.3%）rrs WT1，MUT1。rrs基因第1401位的突变导致对KAN（7/77 = 9%）、AMK（9/77 = 11.68%）和CAP（5/77 = 6.49%）耐药。11株（14.28%）对链霉素耐药的菌株存在rrs基因突变。
具有rrs结构基因突变的分离株对链霉素、KAN、CAP和AMK存在交叉耐药性。A1401G突变的检测对于KAN和AMK耐药性的检测似乎具有100%的特异性。作为首次评估，这些数据通过分子谱分析确定了表型耐药和广泛耐药菌株的存在，并有助于在分子水平上理解氨基糖苷类耐药性。
