Comparison of the bactericidal activity of various fluoroquinolones against Mycobacterium tuberculosis in an in vitro experimental model

• Published in: Journal of antimicrobial chemotherapy 2011-10, Vol.66 (10), p.2281-2283
• Main Authors: Cremades, Rosa, Rodríguez, Juan Carlos, García-Pachón, Eduardo, Galiana, Antonio, Ruiz-García, Montserrat, López, Pilar, Royo, Gloria
• Format: Article
• Language: English
• Subjects: Antibiotics; Antibiotics. Antiinfectious agents. Antiparasitic agents; Antitubercular Agents - pharmacology; Aza Compounds - pharmacology; Bacteria; Biological and medical sciences; Ciprofloxacin - pharmacology; Drug Resistance, Bacterial; Drug therapy; Fluoroquinolones - pharmacology; Humans; Isoniazid - pharmacology; Isoniazid - therapeutic use; Levofloxacin; Medical sciences; Microbial Sensitivity Tests; Mycobacterium tuberculosis; Mycobacterium tuberculosis - classification; Mycobacterium tuberculosis - drug effects; Mycobacterium tuberculosis - growth & development; Mycobacterium tuberculosis - isolation & purification; Ofloxacin - pharmacology; Pathogens; Pharmacology. Drug treatments; Quinolines - pharmacology; Spain; Tuberculosis - microbiology
• ISSN: 0305-7453; 1460-2091
• DOI: 10.1093/jac/dkr281

Objectives To compare the bactericidal activity of various fluoroquinolones against Mycobacterium tuberculosis in the latent and exponential growth phases. Methods Ciprofloxacin, levofloxacin and moxifloxacin were tested against 16 M. tuberculosis clinical isolates (4 resistant and 12 susceptible to fluoroquinolones) from Elche, Spain, isolated between 1992 and 2009. To study bactericidal activity, an inoculum of approximately 105 cfu of each isolate was cultured in Middlebrook 7H9 broth. The broth was previously acidified to pH 4.6 to obtain the microorganism in the stationary phase. Cultures with different concentrations (0.1 to 50 mg/L) of antibiotic and antibiotic-free controls were incubated for 48 h then plated onto Middlebrook 7H11 to detect bacterial killing. In all stages of the process the M. tuberculosis strain ATCC 41323 was included as a quality control to ensure reproducible results. Results Moxifloxacin and levofloxacin were found to exhibit bactericidal activity at lower concentrations and against more strains in both the latent and the exponential growth phases compared with ciprofloxacin. The bactericidal activity of moxifloxacin was greater than that of levofloxacin against microorganisms in the exponential growth phase, but the opposite was true in the latent phase. Conclusions Our data confirm the usefulness of moxifloxacin in the treatment of tuberculosis and suggest that levofloxacin may be used as an alternative drug in the treatment of latent tuberculosis when it is not possible to use isoniazid. Based on the results presented, ciprofloxacin appears to be a poor choice.