Resistance of M. leprae to quinolones: a question of relativity?

UNLABELLED: Multidrug resistant leprosy, defined as resistance to rifampin, dapsone and fluoroquinolones (FQ), has been described in Mycobacterium leprae. However, the in vivo impact of fluoroquinolone resistance, mainly mediated by mutations in DNA gyrase (GyrA2GyrB2), has not been precisely assessed. Our objective was to measure the impact of a DNA gyrase mutation whose implication in fluoroquinolone resistance has been previously demonstrated through biochemical studies, on the in vivo activity of 3 fluoroquinolones: ofloxacin, moxifloxacin and garenoxacin. METHODOLOGY/PRINCIPAL FINDINGS: We used the proportional bactericidal method. 210 four-week-old immunodeficient female Nude mice (NMRI-Foxn1(nu) /Foxn1(nu) ) were inoculated in the left hind footpad with 0.03 ml of bacterial suspension containing 5 × 10(3), 5 × 10(2), 5 × 10(1), and 5 × 10(0) M. leprae AFB organisms of strain Hoshizuka-4 which is a multidrug resistant strain harboring a GyrA A91V substitution. An additional subgroup of 10 mice was inoculated with 5 × 10(-1) bacilli in the untreated control group. The day after inoculation, subgroups of mice were treated with a single dose of ofloxacin, moxifloxacin, garenoxacin or clarithromycin at 150 mg/kg dosing. 12 months later mice were sacrificed and M. leprae bacilli were numbered in the footpad. The results from the untreated control group indicated that the infective inoculum contained 23% of viable M. leprae. The results from the moxifloxacin and garenoxacin groups indicated that a single dose of these drugs reduced the percentage of viable M. leprae by 90%, similarly to the reduction observed after a single dose of the positive control drug clarithromycin. Conversely, ofloxacin was less active than clarithromycin. CONCLUSION/SIGNIFICANCE: DNA gyrase mutation is not always synonymous of lack of in vivo fluoroquinolone activity in M. leprae. As for M. tuberculosis, in vivo studies allow to measure residual antibiotic activity in case of target mutations in M. leprae.

Quinolones for mycobacterial infections.

The fluoroquinolones (FQs) are important agents for the treatment of mycobacterial infections. In leprosy, the use of FQs has enabled a dramatic shortening of formerly long and complicated therapy. Both animal and human studies support the inclusion of certain FQs as a cornerstone of leprosy therapy. In tuberculosis (TB), particularly in multidrug-resistant (MDR) infections, the place of the major antimycobacterial FQs is less clear as there is widespread resistance to these agents in areas of the world in which MDR-TB and extensively drug-resistant (XDR)-TB are prevalent, particularly in Southeast Asia. The place of the newly developed FQ-related diarylquinoline compound known as bedaquiline in the treatment of drug-resistant TB is unclear; however, human studies suggest that it might be effective for this indication.

Sparfloxacin in the treatment of leprosy patients.

Seven men (age range, 20-33 years) with leprosy visited our dermatologic clinic at Yokohama City University Hospital (Table 1) and were entered into a trial of sparfloxacin (SPFX), 100-200 mg daily for up to 1 year. Five patients were Japanese Brazilians or Paraguayan from South America, and two patients were Filipinos. Examination procedures included a detailed medical history, pretreatment, clinical examinations, and body charting of the characteristic skin lesions, areas of anesthesia, and enlarged peripheral nerves. There were no deformities observed in any patient. All had presented with eruptions and neurologic problems. The diagnosis of leprosy and its type were determined by the above examination, skin smear, and histopathologic study, as well as Mitsuda reaction. The first patient came from the Philippines and presented to our clinic in 1993. There were many elevated erythemas with central healing on his whole body. Sensory nerves were impaired. His type was lepromatous (LL) leprosy. The second patient was followed for only 1 month because of a change in residence. The third and fourth patients were brothers. The fifth patient came from Paraguay. The sixth patient was from the Philippines. The seventh patient came to our clinic in April 1995.

Clinical trial of sparfloxacin for lepromatous leprosy.

Nine previously untreated patients with lepromatous leprosy were treated with 200 mg of sparfloxacin daily for 12 weeks to determine whether this drug is bactericidal for Mycobacterium leprae in humans. The efficacy of therapy was monitored both clinically and by measuring changes in morphological index, mouse footpad infectivity, and the radiorespirometric activity of M. leprae organisms obtained from serial biopsy specimens and also by determining titers of phenolic glycolipid-I in serum. Most patients showed clinical improvement within 2 weeks of treatment; this was accompanied by significant reductions in the morphological index, mouse footpad infectivity, and bacillary radiorespirometric activity. After 4 weeks of treatment, all patients had a morphological index of zero and specimens from most patients were noninfectious for mice, while the median decrease in radiorespirometric activity was > 99%. Overall results by the rapid radiorespirometric assay paralleled those of the mouse footpad and morphological index assays. Sparfloxacin given at 200 mg once daily appears to be rapidly bactericidal in humans, with activity similar to that observed in a previous clinical trial with 400 mg of ofloxacin.

Activity of sparfloxacin against Mycobacterium leprae measured by the proportional bactericidal test.

The activity of 25 mg/kg and 50 mg/kg sparfloxacin was measured against Mycobacterium leprae in normal (immunocompetent) mouse foot pads by the proportional bactericidal test. This was compared with the action of 25, 50, and 150 mg/kg ofloxacin by the same method. Sparfloxacin, at both concentrations, was found to be strongly bactericidal by this method, comparable to 150 mg/kg ofloxacin.

Therapeutic efficacy of some new quinolones and a combination of ofloxacin with rifampin against Mycobacterium leprae infection induced in athymic nude mice.

Ofloxacin (OFLX), having superior antileprosy activity among the various quinolones, was studied for its combined therapeutic efficacy with rifampin (RMP) against Mycobacterium leprae infection induced in nude mice. When OFLX (3 mg/mouse) was given to infected mice in combination with RMP (0.01 mg/mouse) by gavage once daily six times per week, from day 31 to day 80 postinfection, a significant combined effect was observed. This study demonstrates the possibility of using OFLX in multidrug regimens for the clinical control of bacilliferous leprosy patients.

Sparfloxacin is more bactericidal than ofloxacin against Mycobacterium leprae in mice.

The comparative bactericidal activities of sparfloxacin and ofloxacin against Mycobacterium leprae in mice were determined using the proportional bactericidal test at doses of 12.5 mg/kg-100 mg/kg. Significant bactericidal activity was found at 12.5 mg/kg sparfloxacin and 25 mg/kg ofloxacin. Sparfloxacin was significantly more bactericidal than ofloxacin at all doses, and the results with 25 mg/kg sparfloxacin were nearly identical to those obtained with 100 mg/kg ofloxacin. These results, together with pharmacokinetic and toxicological data in mice and man, suggest that sparfloxacin may have a higher therapeutic index than ofloxacin in leprosy, and that the tentative standard dosage of 200 mg sparfloxacin daily should be appropriate for a clinical trial.

Terapêutica da hanseníase: situaçäo atual / Therapeutic of leprosy: current situation

O autor enfatiza o tratamento como um dos esteios do controle da hanseníase. Faz revisäo histórica das drogas utilizadas, do mecanismo de açäo, das doses recomendadas e dos principais efeitos colaterais. Ressalta a importância da poliquimioterapia, porposta pela OMS, usando a sulfona, a rifampicina, a clofazimina e a etionamida. Revê o tratamento das reaçöes, oproblema da resistência medicamentosa e o conceito de bacilos persistentes. Apresenta a situaçäo atual da imunoterapia e a esperança depositada em novos fármacos - derivados da quinolona e as ansamicinas. Cita dados promissores das experiências com MDT, supervisionadas pela OMS, e a possibilidade de erradicar ou minimizar o problema da hanseníase nos países onde a doença é endêmica.

Anti-Mycobacterium leprae activity of several quinolones studied in the mouse.

The anti-Mycobacterium leprae activity of several fluoroquinolones (A-56619, A-56620, ofloxacin, fleroxacin, lomefloxacin, temafloxacin, tosufloxacin, and PD-117596) was studied in the mouse. In a dosage of 150 mg/kg administered daily, A-56619 is active and A-56620 is inactive against M. leprae. Ofloxacin administered daily for 2 weeks at 300 mg/kg is bactericidal. The minimal effective dose of PD-117596, lomefloxacin and temafloxacin is less than 37.5 mg/kg. When administered at 300 mg/kg at monthly intervals temafloxacin, PD-117596, and ofloxacin are bacteriostatic; while fleroxacin and lomefloxacin are bactericidal. Tosufloxacin is less active than the other quinolones included in the present study.