Bedewi Zufan, Worku Adane, Mekonnen Yalemtsehay, Yimer Getnet, Medhin Girmay, Mamo Gezahegne, Pieper Rembert, Ameni Gobena
Aklilu Lemma Institute of Pathobiology, Addis Ababa University, P.O. Box 1176, Addis Ababa, Ethiopia.
College of Natural Sciences, Microbial, Cellular and Molecular Biology Department, Addis Ababa University, P.O. Box 1176, Addis Ababa, Ethiopia.
BMC Infect Dis. 2017 Mar 1;17(1):184. doi: 10.1186/s12879-017-2267-2.
Identification of the types of strains of Mycobacterium tuberculosis (M. tuberculosis) complex causing tuberculosis (TB) could contribute to TB control program of specific geographic region as well as it could add knowledge onto the existing literature on TB worldwide. The objective of the present study was to identify the species and strains of M. tuberculosis complex causing pulmonary tuberculosis in central Ethiopia.
A health institution- based cross-sectional study was conducted on 338 smear positive TB cases visiting three hospitals between October 2012 and September 2013. Morning and spot sputum samples were collected before the starting of treatment regimens. Thus, a total of 338 pooled sputum samples collected from these cases. Samples were cultured on Löwenstein Jensen media and the isolates were identified by the region of difference (RD) 9 based polymerase chain reaction (PCR) and spoligotyping.
Of the total isolates 98.6% of the isolates were identified to be M. tuberculosis while the remaining 1.4% were identified as M. africanum. Further, typing of M. tuberculosis using spoligotyping lead to the identification of 90 different strains of M. tuberculosis. Of these strains, 32 were clustered consisting of more than one isolate while the remaining 58 strains were unique consisting of single isolate. Thus, 79.3% (223/281) of the isolates were found in the clustered while only 20.6% (58/281) of the strains were unique. Forty-five of the spolgotyping patterns were registeredin the SITVIT2 or SpolDB4 database in while the remaining 45 were notfound in the database and hence were orphan strains. The dominant strains were SIT53, SIT149, and SIT54, consisting of 43, 37 and 34 isolates, respectively. Classification of the spoligotype patterns using TB-insight RUN TB-Lineage showed that 86.8, 6.4, 5, 1.4% ofthe isolatesbelonged to the Euro-American lineage, East-African-Indian, Indo-oceanic and M. africanum, respectively.
The identification of clustered and new strains using spolygotyping in present study does not give conclusive finding as spoligotyping has low discriminatory power. Thus, further identification of these isolates using mycobacterial interspersed repetitive unit-variable number tandem repeat (MIRU-VENTR) and or whole genome sequencing (WGS) recommended.
鉴定引起结核病（TB）的结核分枝杆菌（M. tuberculosis）复合体的菌株类型，有助于特定地理区域的结核病控制规划，也能为全球现有的结核病文献增添知识。本研究的目的是鉴定埃塞俄比亚中部引起肺结核的结核分枝杆菌复合体的种类和菌株。
2012年10月至2013年9月期间，对前往三家医院就诊的338例涂片阳性结核病病例进行了一项基于卫生机构的横断面研究。在开始治疗方案之前收集清晨和即时痰标本。因此，从这些病例中总共收集了338份混合痰标本。将标本接种在罗-琴培养基上，并通过基于差异区域（RD）9的聚合酶链反应（PCR）和间隔寡核苷酸分型对分离株进行鉴定。
在所有分离株中，98.6%被鉴定为结核分枝杆菌，其余1.4%被鉴定为非洲分枝杆菌。此外，使用间隔寡核苷酸分型对结核分枝杆菌进行分型，鉴定出90种不同的结核分枝杆菌菌株。在这些菌株中，32种为簇状，由多个分离株组成，其余58种为独特型，由单个分离株组成。因此，79.3%（223/281）的分离株属于簇状，而只有20.6%（58/281）的菌株是独特型。45种间隔寡核苷酸分型模式在SITVIT2或SpolDB4数据库中登记，而其余45种在数据库中未找到，因此是孤儿菌株。优势菌株为SIT53、SIT149和SIT54，分别由43、37和34个分离株组成。使用TB-insight RUN TB-Lineage对间隔寡核苷酸分型模式进行分类显示，分别有86.8%、6.4%、5%、1.4%的分离株属于欧美谱系、东非-印度谱系、印度洋谱系和非洲分枝杆菌。
本研究中使用间隔寡核苷酸分型鉴定簇状和新菌株并未得出确凿结果，因为间隔寡核苷酸分型的鉴别力较低。因此，建议使用分枝杆菌插入重复单位-可变数目串联重复序列（MIRU-VENTR）和/或全基因组测序（WGS）对这些分离株进行进一步鉴定。
