Department of Pathology and Microbiology, Aga Khan University Hospital, Karachi, Pakistan.
PLoS One. 2012;7(11):e50551. doi: 10.1371/journal.pone.0050551. Epub 2012 Nov 30.
Rapid new diagnostic methods (including Xpert MTB/RIF assay) use rifampicin resistance as a surrogate marker for multidrug resistant tuberculosis. Patients infected with rifampicin susceptible strains are prescribed first line anti-tuberculosis therapy. The roll out of such methods raises a concern that strains with resistance to other first line anti-tuberculosis drugs including isoniazid will be missed and inappropriate treatment given. To evaluate implications of using such methods review of resistance data from high burden settings such as ours is essential.
To determine resistance to first line anti-tuberculosis drugs amongst rifampicin susceptible pulmonary Mycobacterium tuberculosis (MTB) isolates from Pakistan.
Data of pulmonary Mycobacterium tuberculosis strains isolated in Aga Khan University Hospital (AKUH) laboratory (2009-2011) was retrospectively analyzed. Antimicrobial susceptibility profile of rifampicin susceptible isolates was evaluated for resistance to isoniazid, pyrazinamide, ethambutol, and streptomycin.
Pulmonary specimens submitted to AKUH from 2009 to 2011 yielded 7738 strains of Mycobacterium tuberculosis. These included 54% (n 4183) rifampicin susceptible and 46% (n: 3555) rifampicin resistant strains. Analysis of rifampicin susceptible strains showed resistance to at least one of the first line drugs in 27% (n:1133) of isolates. Overall isoniazid resistance was 15.5% (n: 649), with an isoniazid mono-resistance rate of 4% (n: 174). Combined resistance to isoniazid, pyrazinamide, and ethambutol was noted in 1% (n: 40), while resistance to isoniazid, pyrazinamide, ethambutol, and streptomycin was observed in 1.7% (n: 70) of strains.
Our data suggests that techniques (including Xpert MTB/RIF assay) relying on rifampicin susceptibility as an indicator for initiating first line therapy will not detect patients infected with MTB strains resistant to other first line drugs (including isoniazid). The roll out of these techniques must therefore be accompanied by strict monitoring ensuring early resistance detection to increase chances of improved patient outcomes.
快速新型诊断方法（包括 Xpert MTB/RIF 检测）将利福平耐药作为耐多药结核分枝杆菌的替代标志物。感染利福平敏感株的患者被开具一线抗结核药物治疗。此类方法的推出引起了一种担忧，即可能会遗漏对其他一线抗结核药物（包括异烟肼）耐药的菌株，并给予不适当的治疗。为了评估使用这些方法的影响，必须对来自我们这样的高负担国家的耐药数据进行审查。
确定来自巴基斯坦的利福平敏感型肺结核分枝杆菌（MTB）分离株对一线抗结核药物的耐药情况。
回顾性分析了 Aga Khan 大学医院（AKUH）实验室 2009-2011 年分离的肺结核分枝杆菌菌株的数据。评估了利福平敏感分离株对异烟肼、吡嗪酰胺、乙胺丁醇和链霉素的耐药谱。
2009 年至 2011 年，AKUH 提交的肺部标本共培养出 7738 株结核分枝杆菌。其中 54%（n=4183）为利福平敏感株，46%（n=3555）为利福平耐药株。对利福平敏感株的分析显示，27%（n=1133）的分离株至少对一种一线药物耐药。总的异烟肼耐药率为 15.5%（n=649），异烟肼单耐药率为 4%（n=174）。同时对异烟肼、吡嗪酰胺和乙胺丁醇耐药的比例为 1%（n=40），同时对异烟肼、吡嗪酰胺、乙胺丁醇和链霉素耐药的比例为 1.7%（n=70）。
我们的数据表明，依赖利福平敏感性作为启动一线治疗的指标的技术（包括 Xpert MTB/RIF 检测）将无法检测到感染对其他一线药物（包括异烟肼）耐药的 MTB 菌株的患者。因此，推出这些技术必须同时进行严格监测，以确保早期发现耐药性，提高患者的治疗效果。
