PLoS Medicine：尽早测试有利于耐药结核病防控

David

秘鲁的一项研究表明了用早期药敏测试诊断耐多药结核病的重要性，以及用环境控制措施预防结核病空气传播的必要性。

在秘鲁首都利马的一家医院里进行的这项研究发表在了上周（9月16日）出版的《公共科学图书馆 医学》杂志上。

这组科学家采用了20世纪50年代开发的一种探测系统，该系统让Dos de Mayo医院中同时感染了艾滋病病毒和结核病的患者病房中的所有空气通过房顶的一个饲养着豚鼠的动物房间。还有一组对照组的豚鼠呼吸新鲜空气。

该医院的医学博士、研究的作者之一Marcos avincopa告诉本网站说，从患者和豚鼠身上分离出了结核分枝杆菌菌株。

然后，这组科学家利用DNA和药敏测试发现了哪些病人感染了哪些豚鼠，并确保这些豚鼠不是被其他方式感染的。

他们发现97名患者中只有10名艾滋病/结核病患者造成了几乎所有的豚鼠结核病病例。其中7人患有未经充分治疗的耐药结核病。

该研究的第一作者、英国帝国理工学院传染病和免疫系的医学博士Roderick Escombe说：“该研究表明，重要的是迅速诊断耐多药结核病，而不是等着这些患者接受正常治疗失败，因为尽管这些患者没有被充分治疗，他们可能具有高度传染病，能传播该病。”

avincopa还说：“这清楚地表明一个没有合适的通风的被污染环境是该病的一个强有力的传播者，环境越小、越不通风，传染的几率就越高。”

他还说：“有效的结核病感染控制措施、新鲜空气和通风区域不仅对于医院防止这种细菌的空气传播至关重要，也对于其它卫生环境至关重要，诸如抗逆转录病毒疗法室和乡村医疗中心。”

在这项研究的505天里，患者平均传染性是50年代的研究所记载的6倍。

Escombe还说：“我们不知道豚鼠的结核病感染剂量是否与人类相同。但是和已经发表的关于人类传染性的其它数据相比，我们研究的患者具有高度传染性。”（生物谷Bioon.com）

生物谷推荐原始出处：

PLoS Medicine Vol. 5, No. 9, e188 doi:10.1371/journal.pmed.0050188

The Infectiousness of Tuberculosis Patients Coinfected with HIV

Escombe AR, Moore DAJ, Gilman RH, Pan W, Navincopa M, et al.

Background

The current understanding of airborne tuberculosis (TB) transmission is based on classic 1950s studies in which guinea pigs were exposed to air from a tuberculosis ward. Recently we recreated this model in Lima, Perú, and in this paper we report the use of molecular fingerprinting to investigate patient infectiousness in the current era of HIV infection and multidrug-resistant (MDR) TB.

Methods and Findings

All air from a mechanically ventilated negative-pressure HIV-TB ward was exhausted over guinea pigs housed in an airborne transmission study facility on the roof. Animals had monthly tuberculin skin tests, and positive reactors were removed for autopsy and organ culture for M. tuberculosis. Temporal exposure patterns, drug susceptibility testing, and DNA fingerprinting of patient and animal TB strains defined infectious TB patients. Relative patient infectiousness was calculated using the Wells-Riley model of airborne infection. Over 505 study days there were 118 ward admissions of 97 HIV-positive pulmonary TB patients. Of 292 exposed guinea pigs, 144 had evidence of TB disease; a further 30 were tuberculin skin test positive only. There was marked variability in patient infectiousness; only 8.5% of 118 ward admissions by TB patients were shown by DNA fingerprinting to have caused 98% of the 125 characterised cases of secondary animal TB. 90% of TB transmission occurred from inadequately treated MDR TB patients. Three highly infectious MDR TB patients produced 226, 52, and 40 airborne infectious units (quanta) per hour.

Conclusions

A small number of inadequately treated MDR TB patients coinfected with HIV were responsible for almost all TB transmission, and some patients were highly infectious. This result highlights the importance of rapid TB drug-susceptibility testing to allow prompt initiation of effective treatment, and environmental control measures to reduce ongoing TB transmission in crowded health care settings. TB infection control must be prioritized in order to prevent health care facilities from disseminating the drug-resistant TB that they are attempting to treat.