Hawkey Peter M, Smith E Grace, Evans Jason T, Monk Philip, Bryan Gerry, Mohamed Huda H, Bardhan Madhu, Pugh R Nicholas
Public Health Laboratory, Heartlands Hospital, Birmingham B9 5SS, United Kingdom.
J Clin Microbiol. 2003 Aug;41(8):3514-20. doi: 10.1128/JCM.41.8.3514-3520.2003.
An evaluation of the utility of IS6110-based restriction fragment length polymorphism (RFLP) typing compared to a combination of variable number tandem repeat (VNTR) typing and mycobacterial interspersed repetitive unit (MIRU) typing was undertaken. A total of 53 patient isolates of Mycobacterium tuberculosis from four presumed episodes of cross-infection were examined. Genomic DNA was extracted from the isolates by a cetyl trimethylammonium bromide method. The number of copies of tandem repeats of the five loci ETR(A) to ETR(E) and 12 MIRU loci was determined by PCR amplification and agarose gel electrophoresis of the amplicons. VNTR typing identified the major clusters of strains in the three investigations in which they occurred (each representing a different evolutionary clade: 32333, 42235, and 32433). The majority of unrelated isolates (by epidemiology and RFLP typing) were also identified by VNTR typing. The concordance between the RFLP and MIRU typing was complete, with the exception of two isolates with RFLP patterns that differed by one band each from the rest of the major epidemiologically linked groups of isolates in investigation A. All of these isolates had identical MIRU and VNTR types. A further pair of isolates differed in the number of tandem repeat copies at two MIRU alleles but had identical RFLP patterns. The speed of the combined VNTR and MIRU typing approach enabled results for some of the investigations to be supplied in "real time," influencing choices in contact tracing. The ease of comparison of results of MIRU and VNTR typing, which are recorded as single multidigit numbers, was also found to greatly facilitate investigation management and the communication of results to health care professionals.
对基于IS6110的限制性片段长度多态性（RFLP）分型与可变数目串联重复序列（VNTR）分型和分枝杆菌散布重复单元（MIRU）分型相结合的效用进行了评估。共检查了来自四起假定交叉感染事件的53株结核分枝杆菌患者分离株。通过十六烷基三甲基溴化铵法从分离株中提取基因组DNA。通过对扩增子进行PCR扩增和琼脂糖凝胶电泳，确定五个位点ETR(A)至ETR(E)和12个MIRU位点的串联重复拷贝数。VNTR分型在三项调查中识别出了菌株的主要簇（每项调查代表一个不同的进化分支：32333、42235和32433）。大多数不相关的分离株（根据流行病学和RFLP分型）也通过VNTR分型得以识别。RFLP分型和MIRU分型之间的一致性是完全的，但在调查A中，有两株分离株的RFLP模式与其他主要流行病学相关分离株组中的分离株各相差一条带。所有这些分离株具有相同的MIRU和VNTR类型。另外一对分离株在两个MIRU等位基因处的串联重复拷贝数不同，但具有相同的RFLP模式。VNTR和MIRU分型相结合的方法速度快，使得一些调查结果能够“实时”提供，从而影响接触者追踪的选择。还发现，MIRU和VNTR分型结果易于比较，它们被记录为单个多位数，这极大地促进了调查管理以及向医护人员传达结果。
