Ahmed Mohanad Mohsin, Mohammed Suhad Hadi, Nasurallah Hasan A Abood, Ali Mousa M, Couvin David, Rastogi Nalin
Department of Microbiology, College of Medicine, University of Kerbala, Iraq.
Department of Clinical Laboratory, College of Applied Medical Sciences, University of Kerbala, Iraq.
Int J Mycobacteriol. 2014 Sep;3(3):184-96. doi: 10.1016/j.ijmyco.2014.07.006. Epub 2014 Aug 10.
This study explored the genetic diversity of Mycobacterium tuberculosis isolates in Iraq by spoligotyping and 15-locus-based mycobacterial interspersed repetitive unit-variable number tandem repeat (MIRU-VNTR) methods. Initially, 270 isolates from 134 patients were collected and then 134 non-duplicating isolates (1 isolate/patient) were subjected to the study analyses, 70 isolates were found to be multidrug resistant (MDR) upon testing by proportion method on Löwenstein-Jensen medium. Spoligotyping yielded 39 patterns; 111/134 (82.2%) isolates being grouped in 16 clusters vs. 23/134 (17.2%) isolates being unique. SIT1144/T1 represented the largest cluster (n=20, 14.9%), followed by SIT25/CAS1_Delhi (n=19, 14.2), SIT22/CAS1_Delhi (n=12, 9%); the other clusters ranged from 2 to 8 isolates. The SIT1144 is not reported in neighboring countries and only 4 isolates were reported worldwide (2 in USA, 1 in Venezuela, and 1 in Greece). This study reported 4 isolates belonging to SIT41/Turkey family, and thus it seems that this family is not exclusive to Turkey as previously thought. CAS lineage was predominant in this study (42.5%), followed by ill-defined T (29.9%). Highly diverse MIRU-VNTR genotypes were displayed; 100 distinct MIRU-VNTR genotypes were detected (8 clusters with 2-8 strains/cluster and 92 unique). The clustering rate was 18.03%. The discriminatory efficiency of MIRU-VNTR was high (Hunter-Gaston discriminatory index [HGDI]=0.992); it was higher than that of spoligotyping (HGDI; 0.930). However, the highest discriminatory power was provided by spoligotyping and MIRUs together. Owing to the low clustering rate by MIRU-VNTR, these results suggest that drug-resistance TB in Iraq is due to acquired resistance as opposed to transmission.
Iraq is specific in having its own most predominant lineage (SIT1144/T1) which is not found among neighboring countries. The 15-locus MIRU-VNTR can be useful in discriminating M. tuberculosis isolates in Iraq.
本研究通过间隔寡核苷酸分型（spoligotyping）和基于15个位点的分枝杆菌插入重复单位可变数目串联重复序列（MIRU-VNTR）方法，探索了伊拉克结核分枝杆菌分离株的遗传多样性。最初，收集了来自134名患者的270株分离株，然后对134株非重复分离株（1株/患者）进行研究分析，通过在罗-琴培养基上采用比例法检测，发现70株分离株为多重耐药（MDR）。间隔寡核苷酸分型产生了39种模式；134株中的111株（82.2%）被归为16个簇，而23株（17.2%）为独特型。SIT1144/T1代表最大的簇（n = 20，14.9%），其次是SIT25/CAS1_德里型（n = 19，14.2%），SIT22/CAS1_德里型（n = 12，9%）；其他簇的分离株数量在2至8株之间。邻国未报告SIT1144，全球仅报告了4株（美国2株，委内瑞拉1株，希腊1株）。本研究报告了4株属于SIT41/土耳其家族的分离株，因此看来该家族并不像之前认为的那样仅存在于土耳其。CAS谱系在本研究中占主导地位（42.5%），其次是未明确的T谱系（29.9%）。显示出高度多样的MIRU-VNTR基因型；检测到100种不同的MIRU-VNTR基因型（8个簇，每个簇有2 - 8株菌株，92种独特型）。聚类率为18.03%。MIRU-VNTR的鉴别效率很高（亨特-加斯顿鉴别指数[HGDI]=0.992）；高于间隔寡核苷酸分型（HGDI；0.930）。然而，间隔寡核苷酸分型和MIRU共同提供了最高的鉴别力。由于MIRU-VNTR的聚类率较低，这些结果表明伊拉克的耐多药结核病是由于获得性耐药而非传播所致。
伊拉克有其自身最主要的谱系（SIT1144/T1），邻国未发现。15位点的MIRU-VNTR可用于鉴别伊拉克的结核分枝杆菌分离株。
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