© 2004 American Thoracic Society
Fluoroquinolones in Multidrug-Resistant TuberculosisTo the Editor:Chan and coworkers have shown a good outcome of treating multidrug-resistant tuberculosis (MDR TB) with fluoroquinolones (1). Fluoroquinolones have become indispensable in the treatment of MDR TB (2). As measured by their in vitro activity against Mycobacterium tuberculosis, the most potent of the currently available fluoroquinolones are, in descending order, moxifloxacin, gatifloxacin, levofloxacin, ofloxacin, and ciprofloxacin (1). The first three of these drugs are commonly known as antipneumococcal quinolones used in community-acquired pneumonia. M. tuberculosis clinical isolates that demonstrate high-level phenotypic resistance to fluoroquinolones, which appears to be predominantly due to gyrA mutations, exhibit cross-resistance to all six important fluoroquinolones (3). Patients with prior exposure to any of the quinolones are likely to develop resistance to other quinolones. Quinolones being broad spectrum antibacterial agents, their widespread and indiscriminate use, often in subtherapeutic doses, is likely to rapidly enhance quinolone-resistant organisms, including mycobacteria. MDR TB is increasing due to noninclusion of its treatment protocol in DOTS program. For a long time now there has been no new established drug available for MDR TB. At present we are left with few bacteriostatic antitubercular drugs. Reports of quinolone-resistant tuberculosis are constantly pouring in (4) and should act as a warning sign for the bleak future of cases of MDR-TB, because we are rapidly losing a very effective group of drugs for the management of such cases. So there should be some restriction on the use of fluoroquinolones, to save these drugs for future use in MDR TB. Preventing the emergence of antimicrobial resistance is certainly an important goal. In India (Delhi region), the combined prevalence of drug resistances during 1995 was 13.3% (5). However, even if 2% of new patients in India have MDR TB, this represents 20,000 new drug-resistant infectious cases every year. More than one million new patients with tuberculosis still do not have access to the basic program package in India (6). Identifying patients with MDR TB saves costs by providing effective treatment protocols without wasteful, unnecessary, and ineffective treatment. Furthermore, the primary cycle of MDR TB gets controlled, thereby saving the future funds and indirect costs that would otherwise have to be diverted for the treatment of both sick individuals and those they infect.
Government Medical College Chandigarh, India FOOTNOTES Conflict of Interest Statement: P.R.M. does not have a financial relationship with a commercial entity that has an interest in the subject of this letter. Dr. Michael Iseman was given the opportunity to respond to this letter but declined to do so. REFERENCES
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