No abstract

Fluoroquinolones are widely used for the treatment of bacterial infections and are also second-line therapy for tuberculosis. However, fluoroquinolone resistance in patients with newly diagnosed cases of tuberculosis is not routinely assessed. We performed in vitro susceptibility testing of Mycobacterium tuberculosis to fluoroquinolones for all culture-confirmed tuberculosis cases in adults that were diagnosed at Johns Hopkins Hospital (Baltimore) between January 1998 and March 2002. Fifty-five patients were included in the study; 19 received fluoroquinolone monotherapy before the initiation of antituberculosis therapy. Two of 55 M. tuberculosis isolates (4%; 95% CI, 1%-13%) had decreased susceptibility to fluoroquinolones, including 2 of 19 of those from patients who had received fluoroquinolones (11%; 95% CI, 1%-33%) and 0 of 36 isolates from those who had not (95% CI, 0%-10%). The 2 fluoroquinolone-resistant M. tuberculosis strains were both from patients with acquired immunodeficiency syndrome and a CD4+ lymphocyte count of <50 cells/mm3. The incidence of M. tuberculosis fluoroquinolone resistance in this small sample of patients with newly diagnosed tuberculosis was high, particularly among patients with prior fluoroquinolone exposure.

No abstract

Long-chain lipid envelopes are characteristic of mycobacteria such as those that cause tuberculosis and leprosy. Inhibition of fatty acid synthesis or elongation is a strategy demonstrated to be clinically effective against M. tuberculosis. A new class of compounds designed to inhibit the beta-ketoacyl synthase reaction of fatty acid synthesis has been developed. Of >30 compounds described, the most active were acetamides containing alkylsulfonyl substituents. Inhibitory activities were acutely sensitive to net charge, chain length, and degree of unsaturation. The most active compound 5 (alkyl = C(10)) contained a single methylene spacer between the sulfone and carboxamide and exhibited an MIC of 0.75-1.5 microg/mL, comparable to first-line antituberculosis drugs. These compounds are species-specific, exhibiting no significant activity against bacterial species other than M. tuberculosis and closely related strains. The synthesis, biological activity, and specificity of these compounds are described.