Department of Infectious Diseases, Leiden University Medical Centre, Leiden, The Netherlands.
Int J Tuberc Lung Dis. 2012 Nov;16(11):1477-84. doi: 10.5588/ijtld.12.0129. Epub 2012 Sep 7.
After the diagnosis of a case of tuberculosis (TB), contact tracing is directed by the risk of transmission, for which sputum acid-fast bacilli (AFB) staining results are highly relevant. Limited data are available on the effect of the degree of acid-fast positivity, of a polymerase chain reaction (PCR) result or of bronchoalveolar lavage (BAL) fluid results on the risk of transmission.
To investigate factors associated with TB transmission, focusing on quantitative sputum smear results.
Retrospective study of contact investigations performed over a period of 5 years in a Dutch Municipal Health Service among all index patients with TB, and the tuberculin skin test and chest radiography results in contacts. Three definitions of transmission were used: ≥ 1 or ≥ 5 contacts with positive TST or active TB in contacts.
The highest (+4/+5) sputum AFB grades were associated with the highest relative risk (≥ 8) of extensive transmission or active TB among contacts. Novel risk factors observed were employment or school attendance, positive PCR of sputum and positive AFB staining of BAL fluid. Pulmonary symptoms, infiltrate or cavity and positive AFB sputum stain were also associated with transmission, confirming previous studies.
The risk factors observed in this study may aid in the extension of contact investigations.
在诊断结核病（TB）后，接触者追踪的方向取决于传播风险，而痰抗酸杆菌（AFB）染色结果对此具有高度相关性。关于痰 AFB 阳性程度、聚合酶链反应（PCR）结果或支气管肺泡灌洗液（BAL）结果对传播风险的影响，相关数据有限。
调查与结核病传播相关的因素，重点关注定量痰涂片结果。
对荷兰市立卫生局在 5 年期间进行的接触者调查进行回顾性研究，纳入所有结核病索引患者，以及接触者的结核菌素皮肤试验和胸部 X 线检查结果。使用了三种传播定义：≥ 1 或≥ 5 名 TST 阳性或有活动性结核病的接触者。
最高的（+4/+5）痰 AFB 分级与接触者中广泛传播或活动性结核病的最高相对风险（≥ 8）相关。观察到的新的危险因素包括就业或上学、痰 PCR 阳性和 BAL 液中 AFB 染色阳性。肺部症状、浸润或空洞以及痰 AFB 染色阳性也与传播有关，证实了先前的研究。
本研究观察到的危险因素可能有助于扩展接触者调查。
