Are fluoroquinolones a problem?
By Carol A. Kemper, MD, FACP
Clinical Associate Professor of Medicine
Stanford (CA) University
The widespread use of fluoroquinolones — which are quite active against Mycobacterium tuberculosis — for the treatment of community-acquired pneumonia (CAP) has led to concerns that, in some instances, a diagnosis of TB may be missed or delayed. Dooley and colleagues1 examined 33 recent cases of pulmonary TB diagnosed within the United States, 24 (73%) of whom were first treated for presumed CAP (12 received a fluoroquinolone as monotherapy, four received a fluoroquinolone plus another antibacterial, and seven received an antibiotic other than a fluoroquinolone). Dooley and colleagues compared the outcomes of 16 patients (48%) who received fluoroquinolone with those who did not. The groups were nearly identical at presentation, with a similar frequency of cough, fever, sweats, weight loss, and radiographic findings (13% in each group had cavitary disease).
There was a significant delay in the diagnosis of TB and in the initiation of antituberculous therapy in patients receiving flouroquinolones compared with those who did not receive flouroquinolones (median, 21 vs. five days; P = .04). Patients receiving fluoroquinolones were more frequently discharged before a diagnosis of TB was made (63%) compared with those who did not receive fluoroquinolones (29%). This occurred despite the fact that specimens for AFB smear and culture were obtained within a similar timeframe for both groups, and the frequency of smear-positive disease was similar (31% vs 47%; P > .20). This may have been due to the rapid clinical response to fluoroquinolone therapy observed in some patients: 83% of patients receiving fluoroquinolone monotherapy had significant clinical improvement within an average of three days.
An important concern, not addressed by this study, was whether the empiric use of fluoroquinolone therapy impairs the ability to diagnose pulmonary TB, especially in the event that adequate specimens for smear and culture are not collected at presentation. In addition, fluoroquinolones are an important component of therapy in patients with multidrug resistant disease. While it is generally believed that a period of antibiotic exposure longer than the usual 10- to 14-day course of therapy for CAP is required to induce fluoroquinolone resistance, the widespread use of fluoroquinolones may eventually have a more global effect on the susceptibility of MTb to these agents.
Reference
1. Dooley KE, Golub J, Goes FS, et al. Empiric treatment of community-acquired pneumonia with fluoroquinolones, and delays in the treatment of tuberculosis. Clin Infect Dis 2002; 34:1,607-1,612.
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