Perdigão João, Clemente Sofia, Ramos Jorge, Masakidi Pedro, Machado Diana, Silva Carla, Couto Isabel, Viveiros Miguel, Taveira Nuno, Portugal Isabel
iMed.ULisboa - Instituto de Investigação do Medicamento, Faculdade de Farmácia, Universidade de Lisboa, Lisboa, Portugal.
Hospital da Divina Providência, Serviço de Doenças Infecciosas, Luanda, Angola.
Int J Mycobacteriol. 2016 Dec;5 Suppl 1:S38-S39. doi: 10.1016/j.ijmyco.2016.09.050. Epub 2016 Nov 12.
OBJECTIVE/BACKGROUND: Despite the important role that the African region plays in a global tuberculosis (TB) epidemiological context, many countries in the region still lack data on the prevalence of specific Mycobacterium tuberculosis strains and drug resistance. This is the case for Angola, which presently lacks any data concerning drug-resistance rates and prevalence of specific M. tuberculosis genotypes and respective population structure. In this study, we made the first characterization of the genetic diversity and drug resistance of M. tuberculosis complex strains circulating in Luanda, Angola's most important setting concerning TB epidemiology.
We have analyzed 89 M. tuberculosis isolates recovered from the same number of patients. All clinical isolates were genotyped by spoligotyping and 24-loci mycobacterial interspersed repetitive unit-variable number of tandem repeats (MIRU-VNTRs). First-line drug-susceptibility testing was performed by the standard BACTEC 960 Mycobacteria Growth Indicator Tube (MGIT) procedure.
We have detected 33 different spoligotype profiles corresponding to 24 different shared international types (SITs) and nine orphan profiles. SIT 20 (LAM1) was the most prevalent (n=16, 18.2%) followed by SIT 42 (LAM9; n=15, 17.1%). Overall, the M. tuberculosis population structure in this sample was dominated by LAM (64.8%) and T (33.0%) strains. Twenty-four-loci MIRU-VNTR analysis revealed that a total of 13 isolates were grouped into five distinct clusters. Drug-susceptibility testing revealed a worrying situation concerning resistance rates. Drug-susceptibility data showed that 22 (24.7%) of the 89 clinical isolates were resistant to one or more antibacillary drugs of which four (4.5%) were multidrug resistant (MDR). Drug-resistant isolates were found across distinct clades and MIRU-VNTR clusters.
This first cross-sectional study conducted in Luanda, Angola, provides a framework for future studies and programmatic management of TB in Angola. We provide sufficient evidence for cluster-based transmission with a high predominance of LAM strains, with differential geographic dispersion. The moderate rate of MDR-TB found in this sample has major public health implications and highlights the need for further studies specifically focused on MDR-TB transmission.
目的/背景：尽管非洲地区在全球结核病流行病学背景中发挥着重要作用，但该地区许多国家仍缺乏关于特定结核分枝杆菌菌株的流行率和耐药性的数据。安哥拉就是这种情况，目前该国缺乏任何关于耐药率、特定结核分枝杆菌基因型的流行率及其相应种群结构的数据。在本研究中，我们首次对安哥拉最重要的结核病流行病学地区罗安达流行的结核分枝杆菌复合群菌株的遗传多样性和耐药性进行了特征分析。
我们分析了从相同数量的患者中分离出的89株结核分枝杆菌。所有临床分离株均通过间隔寡核苷酸分型（spoligotyping）和24位点分枝杆菌插入重复单位可变数目串联重复序列（MIRU-VNTR）进行基因分型。一线药物敏感性试验通过标准的BACTEC 960分枝杆菌生长指示管（MGIT）程序进行。
我们检测到33种不同的间隔寡核苷酸分型图谱，对应24种不同的共享国际类型（SITs）和9种孤儿图谱。SIT 20（LAM1）最为常见（n = 16，18.2%），其次是SIT 42（LAM9；n = 15，17.1%）。总体而言，该样本中的结核分枝杆菌种群结构以LAM菌株（64.8%）和T菌株（33.0%）为主。24位点MIRU-VNTR分析显示，共有13株分离株被归为五个不同的簇。药物敏感性试验揭示了令人担忧的耐药率情况。药敏数据显示，89株临床分离株中有22株（24.7%）对一种或多种抗结核药物耐药，其中4株（4.5%）为多重耐药（MDR）。在不同的进化枝和MIRU-VNTR簇中均发现了耐药分离株。
在安哥拉罗安达进行的这项首次横断面研究为安哥拉未来的结核病研究和规划管理提供了一个框架。我们提供了充分的证据证明基于簇的传播，其中LAM菌株占主导地位，且地理分布存在差异。本样本中发现的中度多重耐药结核病发生率对公共卫生具有重大影响，并突出了针对多重耐药结核病传播进行进一步研究的必要性。
