Ben Salah Iskandar, Adékambi Toidi, Raoult Didier, Drancourt Michel
Unité de Recherche sur les Maladies Infectieuses et Tropicales Emergentes, UMR, CNRS-IRD 6236, IFR 48 Faculté de Médecine, Université de la Méditerranée, Marseille, France.
Microbiology (Reading). 2008 Dec;154(Pt 12):3715-3723. doi: 10.1099/mic.0.2008/020164-0.
The Mycobacterium avium complex (MAC) comprises slowly growing mycobacteria responsible for opportunistic infections and zoonoses. The ability to speciate MAC isolates in the clinical microbiology laboratory is critical for determining the organism implicated in clinical disease and for epidemiological investigation of the source of infection. Investigation of a 711 bp variable fragment of rpoB flanked by the Myco-F/Myco-R primers found a 0.7-5.1 % divergence among MAC reference strains, with Mycobacterium chimaera and Mycobacterium intracellulare being the most closely related. Using a 0.7 % divergence cut-off, 83 % of 100 clinical isolates, which had been previously identified by phenotypic characteristics and 16S-23S rDNA intergenic spacer (ITS) probing, were identified as M. avium, 8 % as M. intracellulare and 2 % as M. chimaera. The uniqueness of seven isolates, exhibiting < 99.3 % rpoB sequence similarity with MAC reference strains, was confirmed by 16S rDNA, ITS and hsp65 sequencing and phylogenetic analyses. Partial rpoB gene sequencing using the Myco-F/Myco-R primers permits one-step identification of MAC isolates at the species level and the detection of potentially novel MAC species.
鸟分枝杆菌复合群（MAC）由导致机会性感染和人畜共患病的缓慢生长分枝杆菌组成。在临床微生物实验室对MAC分离株进行菌种鉴定的能力，对于确定临床疾病中涉及的病原体以及对感染源进行流行病学调查至关重要。对由Myco-F/Myco-R引物侧翼的rpoB基因711bp可变片段进行研究发现，MAC参考菌株之间的差异为0.7%-5.1%，其中chimaera分枝杆菌和胞内分枝杆菌关系最为密切。使用0.7%的差异截断值，100株先前通过表型特征和16S-23S rDNA基因间隔区（ITS）探针鉴定的临床分离株中，83%被鉴定为鸟分枝杆菌，8%为胞内分枝杆菌，2%为chimaera分枝杆菌。通过16S rDNA、ITS和hsp65测序及系统发育分析，证实了7株与MAC参考菌株rpoB序列相似性<99.3%的分离株的独特性。使用Myco-F/Myco-R引物进行rpoB基因部分测序，可在种水平上一步鉴定MAC分离株，并检测潜在的新型MAC菌种。
