Kattar Mireille M, Jaafar Rola F, Araj George F, Le Flèche Philippe, Matar Ghassan M, Abi Rached Roland, Khalife Simon, Vergnaud Gilles
Department of Pathology and Laboratory Medicine, American University of Beirut Medical Center, Beirut, Lebanon.
J Clin Microbiol. 2008 Dec;46(12):3935-40. doi: 10.1128/JCM.00464-08. Epub 2008 Oct 15.
Brucellosis remains an important anthropozoonosis worldwide. Brucella species are genetically homogeneous, and thus, the typing of Brucella species for epidemiological purposes by conventional molecular typing methods has remained elusive. Although many methods could segregate isolates into the phylogenetically recognized taxa, limited within-species genetic diversity has been identified. Recently, multilocus variable-number tandem-repeat analysis (MLVA) was found to have a high degree of resolution when it was applied to collections of Brucella isolates from geographically widespread locations, and an assay comprising 16 such loci (MLVA-16) was proposed. This scheme includes eight minisatellite loci (panel 1) and eight microsatellites (panel 2, which is subdivided into panels 2A and 2B). The utility of MLVA-16 for the subtyping of human Brucella isolates from geographically restricted regions needs to be further evaluated, and genotyping databases with worldwide coverage must be progressively established. In the present study, MLVA-16 was applied to the typing of 42 human Brucella isolates obtained from 41 patients recovered from 2002 to 2006 at a tertiary-care center in Lebanon. All isolates were identified as Brucella melitensis by MLVA-16 and were found to be closely related to B. melitensis isolates from neighboring countries in the Middle East when their genotypes were queried against those in the web-based Brucella2007 MLVA database (http://mlva.u-psud.fr/). Panel 2B, which comprised the most variable loci, displayed a very high discriminatory power, while panels 1 and 2A showed limited diversity. The most frequent genotype comprised seven isolates obtained over 7 weeks in 2002, demonstrating an outbreak from a common source. Two isolates obtained from one patient 5 months apart comprised another genotype, indicating relapsing disease. These findings confirm that MLVA-16 has a good discriminatory power for species determination, typing of B. melitensis isolates, and inferring their geographical origin. Abbreviated panel 2B could be used as a short-term epidemiological tool in a small region of endemicity.
布鲁氏菌病在全球范围内仍是一种重要的人畜共患病。布鲁氏菌属在基因上具有同质性，因此，利用传统分子分型方法对布鲁氏菌属进行流行病学分型一直难以实现。尽管许多方法可以将分离株分为系统发育上公认的分类群，但已发现种内遗传多样性有限。最近，多位点可变数目串联重复序列分析（MLVA）在应用于来自地理分布广泛地区的布鲁氏菌分离株集合时，显示出高度的分辨率，并且有人提出了一种包含16个此类位点的检测方法（MLVA - 16）。该方案包括8个小卫星位点（第1组）和8个微卫星位点（第2组，又细分为2A组和2B组）。MLVA - 16用于对来自地理范围有限地区的人类布鲁氏菌分离株进行亚型分型的效用需要进一步评估，并且必须逐步建立覆盖全球的基因分型数据库。在本研究中，MLVA - 16被应用于对从黎巴嫩一家三级医疗中心2002年至2006年康复的41例患者中获得的42株人类布鲁氏菌分离株进行分型。通过MLVA - 16将所有分离株鉴定为羊种布鲁氏菌，并且当将它们的基因型与基于网络的布鲁氏菌2007 MLVA数据库（http://mlva.u - psud.fr/）中的基因型进行比对时，发现它们与中东邻国的羊种布鲁氏菌分离株密切相关。包含最多可变位点的2B组显示出非常高的鉴别力，而第1组和2A组显示出有限的多样性。最常见的基因型包括2002年在7周内获得的7株分离株，表明存在共同来源的暴发。从一名患者相隔5个月获得的2株分离株构成另一种基因型，表明疾病复发。这些发现证实MLVA - 16在物种鉴定、羊种布鲁氏菌分离株分型以及推断其地理来源方面具有良好的鉴别力。简化的2B组可作为地方性流行小区域的短期流行病学工具。
