Verma J S, Nair D, Rawat D, Manzoor N
Department of Microbiology, VMMC and Safdarjung Hospital, New Delhi, India.
Indian J Med Microbiol. 2011 Jul-Sep;29(3):280-2. doi: 10.4103/0255-0857.83913.
Ofloxacin (OFX) is one of the potent fluoroquinolone (FQ) recommended to treat MDR-TB. Over a decade, the preexposure of this drug for the treatment of other bacterial infections has resulted in acquisition of FQ resistance among Mycobacterium tuberculosis strains. Considering this possibility, a study was undertaken in a tertiary care center in the capital city (India) to assess the drug resistance trends of OFX among susceptible and multidrug resistant (MDR) strains of M. tuberculosis.
A total of 102 M. tuberculosis isolates (47 susceptible to first-line drugs and 55 MDR isolates) were screened for susceptibility testing of OFX with a critical concentration of 2 μg/ml by Lowenstein Jensen (LJ) proportion method.
The results showed 40 (85.1%) isolates among 47 susceptible isolates and 34 (61.8%) isolates among 55 MDR isolates, were found to be susceptible to OFX. Fisher's exact test showed significant P-value (0.0136) demonstrating 1.377 fold (95% confidence interval) increased risk to become resistant to OFX than susceptible isolates. These finding shows decreased OFX susceptibility is not only limited to MDR isolates but also increasingly seen in susceptible strains as a result of drug abuse.
Our finding were not alarming, but highlights the general risk of acquiring resistance to OFX, jeopardizing the potential for these drugs to be used as second-line anti-TB agents in the management of drug-resistant TB and creating incurable TB strains .
氧氟沙星（OFX）是推荐用于治疗耐多药结核病的强效氟喹诺酮类药物之一。在过去十多年里，该药物用于治疗其他细菌感染的前期暴露已导致结核分枝杆菌菌株中出现氟喹诺酮耐药性。考虑到这种可能性，在首都（印度）的一家三级护理中心开展了一项研究，以评估氧氟沙星在结核分枝杆菌敏感菌株和耐多药（MDR）菌株中的耐药趋势。
采用罗氏（LJ）比例法，以2μg/ml的临界浓度对总共102株结核分枝杆菌分离株（47株对一线药物敏感，55株耐多药分离株）进行氧氟沙星药敏试验筛选。
结果显示，47株敏感分离株中有40株（85.1%）、55株耐多药分离株中有34株（61.8%）对氧氟沙星敏感。费舍尔精确检验显示P值具有显著性（0.0136），表明耐多药分离株对氧氟沙星耐药的风险比敏感分离株高1.377倍（95%置信区间）。这些发现表明，氧氟沙星敏感性降低不仅限于耐多药分离株，由于药物滥用，在敏感菌株中也越来越常见。
我们的发现并不令人担忧，但突出了获得氧氟沙星耐药性的总体风险，危及这些药物在耐药结核病管理中用作二线抗结核药物的潜力，并产生无法治愈的结核菌株。
