Aurélie Chauffour

Synergistic Activity of R207910 Combined with Pyrazinamide against Murine Tuberculosis

ABSTRACT In previous studies, the diarylquinoline R207910 (also known as TMC207) was demonstrated to have high bactericidal activity when combined with first- or second-line antituberculous drugs. Here we extend the evaluation of R207910 in the curative model of murine tuberculosis by assessing the activities of one-, two-, and three-drug combinations containing R207910 and isoniazid (INH), rifampin (RIF), pyrazinamide (PZA), or moxifloxacin (MXF) in the setting of a high initial bacillary load (7.2 log10 CFU). Two months of treatment with the combinations R207910-PZA, R207910-PZA-INH, R207910-PZA-RIF, or R207910-PZA-MXF resulted in culture-negative lung homogenates in 70 to 100% of the mice, while mice treated with INH-RIF-PZA (the reference regimen) or RIF-MXF-PZA remained culture positive. Combinations including R207910 but not PZA (e.g., R207910-INH-RIF and R207910-MXF-RIF) were less active than R207910-PZA-containing regimens administered either alone or with the addition of INH, RIF, or MXF. These results reveal a synergistic interaction between R207910 and PZA. Three-drug combinations containing these two drugs and INH, RIF, or MXF have the potential to significantly shorten the treatment duration in patients, provided that these results can be confirmed in long-term experiments including periods of relapse.

Genetic Basis for Natural and Acquired Resistance to the Diarylquinoline R207910 in Mycobacteria

ABSTRACT The atpE gene encoding the subunit c of the ATP synthase of Mycobacterium tuberculosis, the target of the new diarylquinoline drug R207910, has been sequenced from in vitro mutants resistant to the drug. The previously reported mutation A63P and a new mutation, I66M, were found. The genetic diversity of atpE in 13 mycobacterial species was also investigated, revealing that the region involved in resistance to R207910 is conserved, except in Mycobacterium xenopi in which the highly conserved residue Ala63 is replaced by Met, a modification that may be associated with the natural resistance of M. xenopi to R207910.

In Vitro and In Vivo Activities of Rifampin, Streptomycin, Amikacin, Moxifloxacin, R207910, Linezolid, and PA-824 against Mycobacterium ulcerans

ABSTRACT Seven antimicrobials were tested in vitro against 29 clinical isolates of Mycobacterium ulcerans. R207910 demonstrated the lowest MIC50 and MIC90, followed by moxifloxacin (MXF), streptomycin (STR), rifampin (RIF), amikacin (AMK), linezolid (LZD), and PA-824. All but PA-824 demonstrated an MIC90 significantly less than the clinically achievable peak serum level. Administered as monotherapy to mice, RIF, STR, AMK, MXF, R207910, and LZD demonstrated some degree of bactericidal activity, whereas PA-824 failed to prevent mortality and to reduce the mean number of CFU in the footpads. Because 4 or 8 weeks of treatment by the combinations RIF-MXF, RIF-R207910, and RIF-LZD displayed bactericidal effects similar to those of RIF-STR and RIF-AMK, these three combinations might be considered as orally administered combined regimens for treatment of Buruli ulcer. Taking into account the cost, potential toxicity, and availability, the combination RIF-MXF appears more feasible for application in the field; additional experiments with mice are warranted to define further its activity against M. ulcerans. In addition, a pilot clinical trial is proposed to test the efficacy of RIF-MXF for treatment of Buruli ulcer.

A Once-Weekly R207910-containing Regimen Exceeds Activity of the Standard Daily Regimen in Murine Tuberculosis

RATIONALE R207910 (TMC207 or J) is a member of the diarylquinolines, a new family of antituberculous drugs with high bactericidal activity when given daily in the murine model of tuberculosis. R207910 exhibits a long half-life and thus is a good candidate for once-weekly therapy of tuberculosis. OBJECTIVES To study the activity of once-weekly R207910 monotherapy and combinations of R207910 with other antituberculous agents (isoniazid, rifapentine, moxifloxacin, and pyrazinamide). METHODS The established infection model of murine tuberculosis was used. Colony counts were determined in the lungs. MEASUREMENTS AND MAIN RESULTS Eight weeks of monotherapy reduced the bacillary load by 3 to 4 log(10) for rifapentine and by 5 to 6 log(10) for R207910 (P < 0.05). The addition of rifapentine and isoniazid or moxifloxacin did not improve the bactericidal activity of R207910 monotherapy. In contrast, the triple combination of R207910 plus rifapentine plus pyrazinamide given once weekly for 2 months (i.e., a total of only eight administrations), was significantly (P < 0.05) more active than R207910 monotherapy or other R207910 combinations, and led to lung culture negativity in 9 of 10 mice, whereas all lungs were culture positive in the groups treated with other drug combinations. Moreover, R207910 plus rifapentine plus pyrazinamide given once weekly was more active than the current standard regimen of rifampin plus isoniazid plus pyrazinamide given five times per week. CONCLUSIONS The unprecedented activity of the triple combination of R207910 plus rifapentine plus pyrazinamide suggests that it may be feasible to develop a fully intermittent once-weekly regimen.

Should Moxifloxacin Be Used for the Treatment of Extensively Drug-Resistant Tuberculosis? An Answer from a Murine Model

ABSTRACT The prevalence of extensively drug-resistant tuberculosis (XDR-TB), defined as TB that is resistant to isoniazid, rifampin, fluoroquinolones, and aminoglycosides, is rising worldwide. The extent of Mycobacterium tuberculosis resistance to fluoroquinolones depends on the mutation in the DNA gyrase, the only target of fluoroquinolones. The MIC of moxifloxacin, the most active fluoroquinolone against M. tuberculosis, may be lower than its peak serum level for some ofloxacin-resistant strains of Mycobacterium tuberculosis. Therefore, if the MIC of moxifloxacin is lower than its peak serum level, it may be effective against XDR-TB. Our objective was to determine the efficacy of moxifloxacin in treating ofloxacin-resistant TB. We selected isogenic fluoroquinolone-resistant mutants of M. tuberculosis H37Rv in vivo. We infected Swiss mice with either wild-type H37Rv or one of three mutant strains with different MICs that are commonly seen in clinical practice. The MICs of the mutant strains ranged from below to above the peak moxifloxacin level seen in humans (3 μg/ml). Each mouse was treated with one of four moxifloxacin doses for 1 month. Moxifloxacin was effective against mutant strain GyrB D500N, with the lowest MIC (0.5 μg/ml), when the standard dose was doubled. Moxifloxacin reduced mortality in mice infected with mutant strain GyrA A90V with an intermediate MIC (2 μg/ml). However, it had no impact on the mutant strain GyrA D94G with the highest MIC (4 μg/ml). Our study underscores current WHO recommendations to use moxifloxacin when there is resistance to early-generation fluoroquinolones such as ofloxacin, restricting this recommendation to strains with moxifloxacin MICs of less than or equal to 2 μg/ml.

Orally Administered Combined Regimens for Treatment of Mycobacterium ulcerans Infection in Mice

ABSTRACT Eight weeks of treatment with rifampin-streptomycin sterilizes Mycobacterium ulcerans infection in mice. Because the bactericidal activity against M. ulcerans of the combination rifampin-moxifloxacin, rifampin-clarithromycin, or moxifloxacin-clarithromycin was similar to that of rifampin-streptomycin, these combinations might be considered as alternative, orally administered combined regimens for treatment of Buruli ulcer in humans.

Bactericidal Activities of R207910 and Other Newer Antimicrobial Agents against Mycobacterium leprae in Mice

ABSTRACT As measured by a proportional bactericidal technique in the mouse footpad system, the bactericidal activity against Mycobacterium leprae of R207910 was equal to that of rifapentine, rifampin, or moxifloxacin and significantly greater than those of minocycline, PA-824, and linezolid. These data suggest that R207910 may play an important role in treatment of leprosy.

Dihydropteroate Synthase Mutations in the folP1 Gene Predict Dapsone Resistance in Relapsed Cases of Leprosy

Molecular detection was compared with the mouse footpad inoculation test for detection of dapsone resistance in 38 strains of Mycobacterium leprae. Mutations of the folP1 gene (at codons 53 or 55) were found in 6 of 6 strains with high-level resistance, in 3 of 4 strains with intermediate-level resistance, and in 1 of 6 strains with low-level resistance, but not in 22 dapsone-susceptible strains. In cases of infection with strains of M. leprae carrying the folP1 mutation, therapy with dapsone may be replaced by therapy with a fluoroquinolone.

Bactericidal and Sterilizing Activities of Several Orally Administered Combined Regimens against Mycobacterium ulcerans in Mice

ABSTRACT Treatment with rifampin-clarithromycin or moxifloxacin-clarithromycin for 8 weeks displayed promising bactericidal activity against Mycobacterium ulcerans in mice; none of the mice treated with rifampin-clarithromycin relapsed, whereas 59% of those treated with moxifloxacin-clarithromycin relapsed after treatment was stopped. The bactericidal and sterilizing activities of the five-times-weekly (5/7) administration of 5 mg of rifapentine/kg of body weight, either alone or in combination, were virtually identical to those of the corresponding regimens with 10 mg of rifampin/kg of body weight; however, because of the long half-life of rifapentine, accumulation of the drug after 5/7 administration is a concern. The bactericidal activity of 20 mg/kg rifapentine in monotherapy or 20 mg/kg rifapentine in combination with 150 mg/kg streptomycin or 200 mg/kg moxifloxacin administered twice weekly was as effective as the corresponding regimens containing 10 mg/kg rifampin administered 5/7, suggesting that Buruli ulcer might be treated with intermittently administered rifapentine-containing combinations.

Curing Mycobacterium ulcerans Infection in Mice with a Combination of Rifampin-Streptomycin or Rifampin-Amikacin

ABSTRACT The curing activities of various durations of treatment with a combination of rifampin (RIF) and either streptomycin (STR) or amikacin (AMK) in murine Mycobacterium ulcerans infection were compared in two experiments. In the first experiment, treatment was begun 1 week after infection, when the inflammatory footpad lesion had not yet occurred (preventive model), and in the second experiment, treatment was begun 6 weeks after infection, when inflammatory footpad lesions were established (curative model). In the first experiment, 4 weeks of treatment with daily RIF-STR or RIF-AMK was able to postpone the occurrence of footpad lesion by 12 weeks (RIF-STR) or 17 weeks (RIF-AMK), thus demonstrating their promising bactericidal activities, but neither treatment was able to prevent the late occurrence of footpad lesions. In the second experiment, the overall cure rates, as assessed by the lack of rebound of inflammatory lesions or remultiplication of M. ulcerans, were only 62% after 2 weeks of treatment with RIF and an aminoglycoside and 85% after 4 weeks; but the cure rate reached 100% after 8 or 12 weeks of treatment. The cure rates were slightly higher with the AMK-containing combination than with the STR-containing combination, but the difference was at the limit of significance (P = 0.07). These results show that in the murine model of Buruli ulcer, 8 weeks is the optimal duration of treatment with a combination of RIF and an aminoglycoside.