Elegail Asrar, Ibrahim Mohamed Nuha Yousif, Mohamed Nour Eman Osman, Hoffner Sven, Haile Melles
National Tuberculosis Reference Laboratory, Khartoum, Sudan.
Department of Public Health Sciences, Karolinska Institutet, Stockholm, Sweden.
Int J Mycobacteriol. 2018 Jul-Sep;7(3):236-241. doi: 10.4103/ijmy.ijmy_82_18.
The aim of this study was to characterize the drug resistance profile, and the specific lineages of Mycobacterium tuberculosis (MTB) strains isolated from patients with pulmonary TB in the state of Khartoum in Sudan.
Consecutive sputum samples and clinical data were collected from 406 smear-positive TB patients with pulmonary TB in 2007-2009. The samples were cultured, and drug susceptibility testing (DST) was performed using the proportion method (PM) on solid Löwenstein-Jensen medium, and species were identified using biochemical methods at the National Reference Laboratory (NRL) in Khartoum. Extracted deoxyribonucleic acid from a total of 120, 60 suspected multidrug-resistant isolates (MDR), and 60 non-MDR isolates were subsequently sent to the WHO supranational reference laboratory (SRL) in Stockholm at the Public Health Agency of Sweden, for confirmation of the drug resistance profile, examinations by line probe assay (LPA), and molecular epidemiology analysis with Spoligotyping.
LPA results correlated 100% for non-MDR and 62% for the suspected MDR strains when compared to the DST results obtained by PM at the NRL. Two strains were initially using the PM identified as MDR-TB but later shown by Hain GenoType Mycobacterium CM/AS to belong Mycobacterium avium complex (Mycobacterium intracelluare). These two strains were excluded from the study material for further analysis. The remaining 58 MDR strains were analyzed using LPA, and 36 strains were confirmed as MDR, 10 as rifampicin monoresistant, and eight as isoniazid-monoresistant. Spoligotyping for all the 118 MTB isolates revealed a total of 115 patterns in which four patterns represented major clusters with a total of 108 (91%) of the strains. The CAS1_Delhi/family was the predominant type and detected in 62 isolates (52%), of which 26 were MDR and 36 were susceptible. It was followed by H3/family with 19 (16%) strains, and 11 Latin American Mediterranean3/family, 16 T2/T1, and two strains each of the Beijing and S lineage.
Comparison of DST results obtained using PM and LPA showed 100% agreement for the non-MDR strains but only 62% for the MDR strains. Taking in consideration the time, risk of contamination and the cost of labour to identify MDR TB, the LPA have clear advantages in early detection of MDRTB than the PM. Additionally in this study material Spoligotyping revealed the CAS1 Delhi as the most predominant family. We could not see no major difference in lineages between MDR and non-MDR strains.
本研究旨在描述从苏丹喀土穆州肺结核患者中分离出的结核分枝杆菌（MTB）菌株的耐药谱及特定谱系。
2007年至2009年期间，连续收集了406例涂片阳性的肺结核患者的痰液样本和临床数据。对样本进行培养，并在固体罗氏培养基上采用比例法（PM）进行药敏试验（DST），在喀土穆的国家参考实验室（NRL）使用生化方法鉴定菌种。随后，从总共120株疑似多重耐药菌株（MDR）中的60株以及60株非MDR菌株中提取的脱氧核糖核酸被送往瑞典公共卫生署位于斯德哥尔摩的世界卫生组织超国家参考实验室（SRL），以确认耐药谱、通过线性探针分析（LPA）进行检测以及采用间隔寡核苷酸分型法进行分子流行病学分析。
与NRL通过PM获得的DST结果相比，LPA结果显示非MDR菌株的一致性为100%，疑似MDR菌株的一致性为62%。最初使用PM鉴定为耐多药结核病（MDR-TB）的两株菌株，后来经海因基因型结核分枝杆菌复合群/非结核分枝杆菌检测显示属于鸟分枝杆菌复合群（胞内分枝杆菌）。这两株菌株被排除在研究材料之外，不再进行进一步分析。对其余58株MDR菌株进行LPA分析，其中36株被确认为MDR，10株为仅对利福平耐药，8株为仅对异烟肼耐药。对所有118株MTB分离株进行间隔寡核苷酸分型法检测，共发现115种模式，其中四种模式代表主要聚类，共有108株（91%）菌株。CAS1_Delhi/家族是主要类型，在62株（52%）分离株中检测到，其中26株为MDR，36株敏感。其次是H3/家族，有19株（16%），11株拉丁美洲地中海型3/家族，16株T2/T1型，以及北京和S谱系各两株。
使用PM和LPA获得的DST结果比较显示，非MDR菌株的一致性为100%，而MDR菌株仅为62%。考虑到鉴定MDR-TB所需的时间、污染风险和人工成本，LPA在早期检测MDR-TB方面比PM具有明显优势。此外，在本研究材料中，间隔寡核苷酸分型法显示CAS1 Delhi是最主要的家族。我们未发现MDR和非MDR菌株在谱系上有重大差异。
