Dahle Ulf R, Sandven Per, Heldal Einar, Caugant Dominique A
Norwegian Institute of Public Health, Nydalen, N-0403 Oslo, Norway.
J Clin Microbiol. 2003 Jul;41(7):2968-73. doi: 10.1128/JCM.41.7.2968-2973.2003.
In this study, we determined the genetic diversity of Mycobacterium tuberculosis isolated in Norway from 1999 to 2001. The results were compared to those for strains isolated from 1994 to 1998. A total of 818 patients were diagnosed with tuberculosis (TB) during the last 3-year period. Of these cases, 576 (70%) were verified by culturing, and strains from 551 patients (96%) were analyzed by the IS6110 restriction fragment length polymorphism (RFLP) method. We excluded 13 strains (2.4%) from the analyses, since they were found to represent false-positive samples. A total of 67 strains (12%) that carried fewer than five copies of IS6110 were analyzed by spoligotyping. The strains were from 157 patients (29%) of Norwegian origin and 381 patients (71%) of foreign origin. The rate of diversity among all of the strains was 90%, while in 1994 to 1998 it was 87%. Clusters were assumed to have arisen from recent transmission; the degree of such transmission was 10% in 1999 to 2001, while for the whole 8-year period (1994 to 2001), it was 11%. Of the 109 patients diagnosed as being part of a cluster in 1999 to 2001, 89 were infected with a strain that carried more than four copies of IS6110. Among these 89 patients, 52 (58%) were infected with a strain that had already been identified in 1994 to 1998. The results indicated that most cases of TB in Norway were due to the import of new strains rather than to transmission within the country. This finding demonstrates that screening of immigrants for TB upon arrival in Norway needs to be improved. Outbreaks, however, were caused mainly by strains that have been circulating in Norway for many years.
在本研究中,我们测定了1999年至2001年在挪威分离出的结核分枝杆菌的遗传多样性。将结果与1994年至1998年分离出的菌株的结果进行了比较。在过去3年期间,共有818名患者被诊断患有结核病(TB)。在这些病例中,576例(70%)通过培养得到证实,来自551名患者(96%)的菌株采用IS6110限制性片段长度多态性(RFLP)方法进行分析。我们将13株菌株(2.4%)排除在分析之外,因为它们被发现代表假阳性样本。共有67株携带少于5个IS6110拷贝的菌株通过间隔寡核苷酸分型(spoligotyping)进行分析。这些菌株来自157名(29%)挪威籍患者和381名(71%)外籍患者。所有菌株的多样性率为90%,而在1994年至1998年为87%。假定簇状菌株源自近期传播;1999年至2001年这种传播程度为10%,而在整个8年期间(1994年至2001年)为11%。在1999年至2001年被诊断为簇状病例的109名患者中,89名感染了携带超过4个IS6110拷贝的菌株。在这89名患者中,52名(58%)感染了1994年至1998年已鉴定出的菌株。结果表明,挪威的大多数结核病病例是由于新菌株的输入而非国内传播。这一发现表明,需要改进对抵达挪威的移民进行结核病筛查的工作。然而,疫情主要是由在挪威传播多年的菌株引起的。