Langlois-Klassen Deanne, Kunimoto Dennis, Saunders L Duncan, Chui Linda, Boffa Jody, Menzies Dick, Long Richard
Department of Public Health Sciences, University of Alberta, Edmonton, Canada.
PLoS One. 2012;7(6):e38431. doi: 10.1371/journal.pone.0038431. Epub 2012 Jun 5.
Mycobacterium tuberculosis Beijing strains are frequently associated with tuberculosis outbreaks and drug resistance. However, contradictory evidence and limited study generalizability make it difficult to foresee if the emergence of Beijing strains in high-income immigrant-receiving countries poses an increased public health threat. The purpose of this study was to determine if Beijing strains are associated with high risk disease presentations relative to other strains within Canada.
This was a retrospective population-based study of culture-confirmed active TB cases in a major immigrant-receiving province of Canada in 1991 through 2007. Of 1,852 eligible cases, 1,826 (99%) were successfully genotyped. Demographic, clinical, and mycobacteriologic surveillance data were combined with molecular diagnostic data. The main outcome measures were site of disease, lung cavitation, sputum smear positivity, bacillary load, and first-line antituberculosis drug resistance.
A total of 350 (19%) patients had Beijing strains; 298 (85%) of these were born in the Western Pacific. Compared to non-Beijing strains, Beijing strains were significantly more likely to be associated with polyresistance (aOR 1.8; 95% CI 1.0-3.3; p = 0.046) and multidrug-resistance (aOR 3.4; 1.0-11.3; p = 0.049). Conversely, Beijing strains were no more likely than non-Beijing strains to be associated with respiratory disease (aOR 1.3; 1.0-1.8; p = 0.053), high bacillary load (aOR 1.2; 0.6-2.7), lung cavitation (aOR 1.0; 0.7-1.5), immediately life-threatening forms of tuberculosis (aOR 0.8; 0.5-1.6), and monoresistance (aOR 0.9; 0.6-1.3). In subgroup analyses, Beijing strains only had a significant association with multidrug-resistant tuberculosis (aOR 6.1; 1.2-30.4), and an association of borderline significance with polyresistant tuberculosis (aOR 1.8; 1.0-3.5; p = 0.062), among individuals born in the Western Pacific.
Other than an increased risk of polyresistant or multidrug-resistant tuberculosis, Beijing strains appear to pose no more of a public health threat than non-Beijing strains within a high-income immigrant-receiving country.
结核分枝杆菌北京基因型菌株常与结核病暴发及耐药性相关。然而，相互矛盾的证据以及有限的研究普遍性使得难以预见在高收入移民接收国家中北京基因型菌株的出现是否会带来更大的公共卫生威胁。本研究的目的是确定在加拿大境内，相对于其他菌株，北京基因型菌株是否与高风险疾病表现相关。
这是一项基于人群的回顾性研究，研究对象为1991年至2007年加拿大一个主要移民接收省份中经培养确诊的活动性肺结核病例。在1852例符合条件的病例中，1826例（99%）成功进行了基因分型。将人口统计学、临床和分枝杆菌学监测数据与分子诊断数据相结合。主要结局指标为疾病部位、肺空洞形成、痰涂片阳性、菌量以及一线抗结核药物耐药性。
共有350例（19%）患者感染北京基因型菌株；其中298例（85%）出生于西太平洋地区。与非北京基因型菌株相比，北京基因型菌株更易出现多耐药（调整后比值比1.8；95%置信区间1.0 - 3.3；p = 0.046）和耐多药（调整后比值比3.4；1.0 - 11.3；p = 0.049）。相反，北京基因型菌株与非北京基因型菌株相比，在呼吸道疾病（调整后比值比1.3；1.0 - 1.8；p = 0.053）、高菌量（调整后比值比1.2；0.6 - 2.7）、肺空洞形成（调整后比值比1.0；0.7 - 1.5）、直接危及生命的结核病形式（调整后比值比0.8；0.5 - 1.6）以及单耐药（调整后比值比0.9；0.6 - 1.3）方面并无差异。在亚组分析中，仅在出生于西太平洋地区的个体中，北京基因型菌株与耐多药结核病显著相关（调整后比值比6.1；1.2 - 30.4），与多耐药结核病的相关性接近显著（调整后比值比1.8；1.0 - 3.5；p = 0.062）。
除了多耐药或耐多药结核病风险增加外，在高收入移民接收国家中，北京基因型菌株似乎并未比非北京基因型菌株构成更大的公共卫生威胁。
