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BackgroundBedaquiline (BDQ), by targeting the electron transport chain and having a long half-life, is a good candidate to simplify leprosy treatment. Our objectives were to (i) determine the minimal effective dose (MED) of oral BDQ, (ii) evaluate the benefit of adding another inhibitor of the respiratory chain to oral BDQ (i.e.clofazimine (CFZ)) and (iii) evaluate the benefit of an intramuscular injectable long-acting formulation of BDQ (intramuscular BDQ; BDQ-LA IM), in a murine model of leprosy.Methodology/ Principal FindingsTo determine the MED of oral BDQ and the benefit of adding CFZ, 100 four-week-old female nude mice were inoculated in the footpads with 5.103bacilli ofM. lepraestrain THAI53. Mice were randomly allocated into: 1 untreated group, 5 groups treated with oral BDQ (0.10 to 25 mg/kg), 3 groups treated with CFZ 20 mg/kg alone or combined with oral BDQ 0.10 or 0.33 mg/kg, and 1 group treated with rifampicin (RIF) 10 mg/kg. Mice were treated 5 days a week during 24 weeks.To evaluate the benefit of the BDQ-LA IM, 340 four-week-old female Swiss mice were inoculated in the footpads with 5.103to 5.101bacilli (or 5.100for the untreated control group) ofM. lepraestrain THAI53. Mice were randomly allocated into the following 11 groups treated with a single dose (SD) or 3 doses (3D) 24h after the inoculation: 1 untreated group, 2 treated with RIF 10 mg/kg SD or 3D, 8 treated with oral BDQ or BDQ-LA IM 2 or 20 mg/kg, SD or 3D.Twelve months later, mice were sacrificed andM. lepraebacilli enumerated in the footpad. All the footpads became negative with BDQ at 3.3 mg/kg. The MED of oral BDQ againstM. lepraein this model is therefore 3.3 mg/kg. The addition of CFZ to a dose of BDQ 10-fold lower than this MED increased the bactericidal activity of BDQ suggesting synergies between both drugs. The BDQ-LA IM displayed similar or lower bactericidal activity than the oral BDQ.ConclusionWe demonstrated that the MED of oral BDQ againstM. lepraewas 3.3 mg/kg in mice and the addition of CFZ to oral BDQ may improve the efficacy of BDQ. BDQ-LA IM was similar or less active than oral BDQ at equivalent dosing and frequency but should be tested at higher dosing in order to reach equivalent exposure in further experiments.

Background The fact that Mycobacterium leprae does not grow in vitro remains a challenge in the survey of its antimicrobial resistance (AMR). Mainly molecular methods are used to diagnose AMR in M. leprae to provide reliable data concerning mutations and their impact. Fluoroquinolones (FQs) are efficient for the treatment of leprosy and the main second-line drugs in case of multidrug resistance. Objectives This study aimed at performing a systematic review (a) to characterize all DNA gyrase gene mutations described in clinical isolates of M. leprae, (b) to distinguish between those associated with FQ resistance or susceptibility and (c) to delineate a consensus numbering system for M. leprae GyrA and GyrB. Data sources Data source was PubMed. Study eligibility criteria Publications reporting genotypic susceptibility-testing methods and gyrase gene mutations in M. leprae clinical strains. Results In 25 studies meeting our inclusion criteria, 2884 M. leprae isolates were analysed (2236 for gyrA only (77%) and 755 for both gyrA and gyrB (26%)): 3.8% of isolates had gyrA mutations (n = 110), mostly at position 91 (n = 75, 68%) and 0.8% gyrB mutations (n = 6). Since we found discrepancies regarding the location of substitutions associated with FQ resistance, we established a consensus numbering system to properly number the mutations. We also designed a 3D model of the M. leprae DNA gyrase to predict the impact of mutations whose role in FQ-susceptibility has not been demonstrated previously. Conclusions Mutations in DNA gyrase are observed in 4% of the M. leprae clinical isolates. To solve discrepancies among publications and to distinguish between mutations associated with FQ resistance or susceptibility, the consensus numbering system we proposed as well as the 3D model of the M. leprae gyrase for the evaluation of the impact of unknown mutations in FQ resistance, will provide help for resistance surveillance.

Mycobacterium ulcerans is the causative agent of Buruli ulcer, a neglected tropical skin disease that is most commonly found in children from West and Central Africa. Despite the severity of the infection, therapeutic options are limited to antibiotics with severe side effects. Here, we show that M. ulcerans is susceptible to the anti-tubercular drug Q203 and related compounds targeting the respiratory cytochrome bc1:aa3. While the cytochrome bc1:aa3 is the primary terminal oxidase in Mycobacterium tuberculosis, the presence of an alternate bd-type terminal oxidase limits the bactericidal and sterilizing potency of Q203 against this bacterium. M. ulcerans strains found in Buruli ulcer patients from Africa and Australia lost all alternate terminal electron acceptors and rely exclusively on the cytochrome bc1:aa3 to respire. As a result, Q203 is bactericidal at low dose against M. ulcerans replicating in vitro and in mice, making the drug a promising candidate for Buruli ulcer treatment., Mycobacterium ulcerans is the causative agent of Buruli ulcer (BU). Existing anti-tubercular drugs have been used to treat the condition with varying success. Here, the authors show that a clinical-stage drug candidate for tuberculosis, Q203, is effective at killing M. ulcerans and is a promising therapeutic candidate for BU.

Buruli ulcer (BU), caused by Mycobacterium ulcerans, is currently treated with a daily combination of rifampin and either injectable streptomycin or oral clarithromycin. An intermittent oral regimen would facilitate treatment supervision. We first evaluated the bactericidal activity of newer antimicrobials against M. ulcerans using a BU animal model. The imidazopyridine amine telacebec (Q203) exhibited high bactericidal activity whereas tedizolid (an oxazolidinone closely related to linezolid), selamectin and ivermectin (two avermectine compounds) and the benzothiazinone PBTZ169 were not active. Consequently, telacebec was evaluated for its bactericidal and sterilizing activities in combined intermittent regimens. Telacebec given twice a week in combination with a long-half-life compound, either rifapentine or bedaquiline, sterilized mouse footpads in 8 weeks, i.e. after a total of only 16 doses, and prevented relapse during a period of 20 weeks after the end of treatment. These results are very promising for future intermittent oral regimens which would greatly simplify BU treatment in the field., Author summary The current treatment for Buruli ulcer (BU), an infection caused by Mycobacterium ulcerans, is based on a daily antibiotic combination of rifampin associated with streptomycin or clarithromycin. A shorter or intermittent treatment without an injectable drug would clearly simplify the management in the field. We evaluated the bactericidal activity of several new antimicrobial drugs in a mouse model of BU and found that telacebec (Q203) exhibited the greatest bactericidal effect. We subsequently identified new antibiotic combinations containing telacebec with high sterilizing activity when administered twice a week for 8 weeks, i.e. at a total of only 16 doses.

Human settlement of Madagascar traces back to the beginning of the first millennium with the arrival of Austronesians from Southeast Asia, followed by migrations from Africa and the Middle East. Remains of these different cultural, genetic, and linguistic legacies are still present in Madagascar and other islands of the Indian Ocean. The close relationship between human migration and the introduction and spread of infectious diseases, a well-documented phenomenon, is particularly evident for the causative agent of leprosy, Mycobacterium leprae. In this study, we used whole-genome sequencing (WGS) and molecular dating to characterize the genetic background and retrace the origin of the M. leprae strains circulating in Madagascar (n = 30) and the Comoros (n = 3), two islands where leprosy is still considered a public health problem and monitored as part of a drug resistance surveillance program. Most M. leprae strains (97%) from Madagascar and Comoros belonged to a new genotype as part of branch 1, closely related to single nucleotide polymorphism (SNP) type 1D, named 1D-Malagasy. Other strains belonged to the genotype 1A (3%). We sequenced 39 strains from nine other countries, which, together with previously published genomes, amounted to 242 genomes that were used for molecular dating. Specific SNP markers for the new 1D-Malagasy genotype were used to screen samples from 11 countries and revealed this genotype to be restricted to Madagascar, with the sole exception being a strain from Malawi. The overall analysis thus ruled out a possible introduction of leprosy by the Austronesian settlers and suggests a later origin from East Africa, the Middle East, or South Asia.

Buruli ulcer (BU), caused by Mycobacterium ulcerans is currently treated by a daily combination of rifampin and either injectable streptomycin or oral clarithromycin. An intermittent oral regimen would facilitate the treatment supervision. We first evaluated the bactericidal activity of newer antimicrobials against M. ulcerans using a BU animal model. The imidazopyridine amine Q203 exhibited high bactericidal activity whereas tedizolid (oxazolidinone close to linezolid), selamectine and ivermectine (avermectine compound) and the benzothiazinone PBTZ169 were not active. Consequently, Q203 was evaluated for its bactericidal and sterilizing activities in combined intermittent regimens. Q203 given twice a week in combination with one of the other long half-life compounds, rifapentine or bedaquiline, sterilized the mice footpads in 8 weeks, i.e. after a total of only 16 doses, and prevented relapse during a period of 20 weeks after stopping the treatment. These results are very promising for future intermittent oral regimens which would greatly simplify BU treatments in the field.Author summaryThe current treatment of Buruli ulcer (BU), infection caused by Mycobacterium ulcerans is based on a daily antibiotic combination of rifampin associated with streptomycin or clarithromycin. A shorter or intermittent treatment without an injectable drug would clearly simplify the management on the field. We evaluated the bactericidal activity of several new antimicrobials drugs in a mice model of BU and found that the Q203 exhibited the highest bactericidal effect. We subsequently identified new antibiotic combinations containing Q203 with high sterilizing activity when administrated twice a week for 8 weeks.

Antimicrobial resistance (AMR) in leprosy is mostly unknown because Mycobacterium leprae does not grow in vitro and bacteriologic investigations have been abandoned. However, molecular detection of resistance can be applied to multibacillary cases. Patients living in France mainland or in the French territories and diagnosed with leprosy from 2001 to 2015 were prospectively studied for AMR by detecting mutations in rpoB for rifampicin resistance, in folP1 for dapsone and in gyrA for ofloxacin. Single nucleotide polymorphism (SNP) genotypes 1–4 were determined for resistant strains. Of 334 skin biopsy samples received for suspicion of leprosy, 184 (55.1%) were positive for M. leprae (acid-fast bacilli and M. leprae–specific repetitive element PCR) corresponding to 160 multibacillary cases. AMR was detected in 18 cases (11.3%): 13 cases (8.1%) of dapsone resistance, three (1.9%) rifampicin and two (1.3%) ofloxacin. There were no strains with multidrug resistance. The mutations (numbering system of M. leprae TN strain genome) found were P55L (n = 7), T53I (n = 5), T53A (n = 1) in folP1; S456L (n = 2) and S456F (n = 1) in rpoB; and A91V (n = 2) in gyrA. Resistance proportion differ significantly between new and relapse cases (9/127, 7.0%, vs. 9/33, 25.7%, p 0.003). The frequency distribution of SNP1–4 types of resistant strains was two, one, 12 and three with five SNP3 cases from New Caledonia harbouring the same T53I FolP1 substitution. This is the first report of AMR surveillance for new and relapse cases of leprosy in Europe. Detection of resistance helped in individual treatment as well as in epidemiologic investigations.

BackgroundThe World Health Organization recommends supervising the treatment of tuberculosis. Intermittent regimens have the potential to simplify the supervision and improve compliance. Our objective was to analyse the sterilising activity of once-weekly regimens based on drugs with a long half-life, bedaquiline and rifapentine, in a murine model of tuberculosis.Methods300 Swiss mice were infected intravenously infected with ×10−6 CFU Mycobacterium tuberculosis H37Rv. Mice were treated once weekly with regimens containing: 1) bedaquiline, rifapentine and pyrazinamide (BPZ); 2) BPZ plus moxifloxacin (BPZM); 3) BPZM plus clofazimine (BPZMC); 4) the standard daily regimen of tuberculosis. All regimens were given for 4 or 6 months. Bactericidal and sterilising activity were assessed.ResultsAfter 2 months of treatment, the mean count in lungs was 0.76±0.60 log10 CFU in mice treated with the daily control regimen and negative in all mice treated with once-weekly regimens (pversus 4-month daily control; p>0.05 for all once-weekly regimens versus 6-month daily control).ConclusionsBPZ-based once-weekly regimens have higher sterilising activity than the standard daily regimen and could greatly simplify treatment administration and possibly shorten the duration of tuberculosis treatment.

Introduction Les traitements actuels de la tuberculose (TB) a bacilles sensibles sont longs et imposent une supervision pour que l’observance soit bonne. Un traitement hebdomadaire plutot que quotidien simplifierait cette supervision. La bedaquiline et la rifapentine dont la demi-vie est longue sont de bons candidats pour la mise au point d’un traitement hebdomadaire. L’objectif de cette etude est d’analyser, dans un modele murin de TB, l’activite sterilisante de regimes hebdomadaires a base de bedaquiline et de rifapentine. L’activite sterilisante, est la capacite d’un traitement a prevenir les rechutes a l’issue du traitement. Il s’agit de l’etape preclinique ultime avant de proposer un essai clinique. Methodes Trois cent souris Swiss femelles ont ete inoculees par voie intraveineuse par 1,03 × 106 unites formant colonies (UFC) de la souche H37Rv de Mycobacterium tuberculosis. Les souris ont ete traitees soit une fois par semaine par un regime associant bedaquiline, pyrazinamide, rifapentine (regime BPZ), plus ou moins de la moxifloxacine (regime BPZM) et de la clofazimine (regime BPZMC), pendant 4 ou 6 mois, soit par le traitement standard quotidien de la TB a bacilles sensibles rifampicine, isoniazide et pyrazinamide (regime RHZ). L’activite bactericide a ete evaluee par la mesure des charges bacillaires pulmonaires a 2, 4 et 6 mois et l’activite sterilisante sera evaluee par la proportion de souris en rechute 3 mois apres l’arret du traitement. Les charges bacillaires ont ete comparees avec le test non parametrique de Mann–Whitney–Wilcoxon. Resultats A l’initiation du traitement, la charge bacillaire pulmonaire etait de 4,60 ± 1,26 log 10 UFC. A 2 mois, elle etait de 6,03 ± 1,70 log 10 UFC chez les souris non traitees, 0,57 ± 0,63 log10 UFC chez les souris traitees par le regime standard et nulle chez les souris traitees par les regimes hebdomadaires (p Conclusion Les premiers resultats de cette etude montrent que les regimes hebdomadaires a base de bedaquiline et rifapentine ont, une activite bactericide superieure a celle du regime standard quotidien actuel de la TB a bacilles sensibles. Si ces donnees sont confirmees en termes d’activite sterilisante, ces regimes pourraient etre proposes pour un essai clinique.

International audience; Background: Moxifloxacin retains partial activity against some fluoroquinolone-resistant mutants of Mycobacterium tuberculosis. Levofloxacin is presumed to be as active as moxifloxacin against drug-susceptible tuberculosis and to have a better safety profile.Objectives: To compare the in vivo activity of levofloxacin and moxifloxacin against M. tuberculosis strains with various levels of fluoroquinolone resistance.Methods: BALB/c mice were intravenously infected with 106M. tuberculosis H37Rv and three isogenic mutants: GyrA A90V, GyrB E540A and GyrB A543V. Treatment with 50 or 100 mg/kg levofloxacin and 60 or 66 mg/kg moxifloxacin was given orally every 6 h, for 4 weeks.Results: Levofloxacin 50 and 100 mg/kg q6h and moxifloxacin 60 and 66 mg/kg q6h generated AUCs in mice equivalent to those of levofloxacin 750 and 1000 mg/day and moxifloxacin 400 and 800 mg/day, respectively, in humans. Moxifloxacin 60 and 66 mg/kg q6h had bactericidal activity against strain H37Rv (MIC ≤ 0.25 mg/L) and mutants GyrB E540A and GyrB A543V (MIC = 0.5 mg/L). Against mutant GyrA A90V (MIC = 2 mg/L), moxifloxacin 60 mg/kg q6h did not prevent bacillary growth, whereas 66 mg/kg q6h had bacteriostatic activity. Levofloxacin 50 mg/kg q6h had bactericidal activity against H37Rv (MIC ≤ 0.25 mg/L) but not against the mutant strains. Levofloxacin 100 mg/kg q6h had bactericidal activity against H37Rv and mutants GyrB E540A (MIC = 0.5 mg/L) and GyrB A543V (MIC= 1 mg/L) but not against mutant GyrA A90V (MIC = 4 mg/L).Conclusions: All mutations reduced fluoroquinolone activity, even those classified as susceptible according to phenotypic tests. High-dose levofloxacin is less effective than high-dose moxifloxacin against both fluoroquinolone-resistant and -susceptible M. tuberculosis strains in mice.

OBJECTIVES Heteroresistance, described both in terms of various point mutations resulting in different levels of resistance and in terms of a mixture of mutant and WT bacilli, is identified in up to one-third of fluoroquinolone (FQ)-resistant Mycobacterium tuberculosis isolates. Heteroresistance is a challenge for current phenotypic and genotypic susceptibility testing (DST) regimes. We aimed to compare the performances of different phenotypic and genotypic DST in the context of FQ heteroresistance by mimicking, in a murine model, the course of selection of FQ resistance during treatment. METHODS The capacity of different phenotypic DST [Lowenstein-Jensen (LJ) medium containing either 2 mg/L ofloxacin or 0.5, 1 or 2 mg/L moxifloxacin] and genotypic DST (gyrA/B Sanger sequencing) to detect FQ resistance was analysed. RESULTS Ninety-seven percent of mice harboured a heterogeneous population. The proportion of mice in which FQ resistance was detected varied according to the medium used (97% for 0.5 mg/L moxifloxacin, 80% for 2 mg/L ofloxacin, 47% for 1 mg/L moxifloxacin and 25% for 2 mg/L moxifloxacin). Compared with phenotypic DST, genotypic DST had a low sensitivity for detection of resistance (33%). CONCLUSIONS Our study shows the in vivo complexity of FQ resistance emergence and the poor sensitivity of Sanger DNA sequencing for detection of heteroresistance. Our data support the use of 0.5 mg/L moxifloxacin in LJ for detection of FQ resistance, but not the recent increase in the ofloxacin critical concentration from 2 to 4 mg/L given in the WHO recommendations.

Background The treatment of Buruli ulcer (BU) that is caused by Mycobacterium ulcerans, is currently based on a daily administration of rifampin and streptomycin (RIF-STR). A fully oral intermittent regimen would greatly simplify its treatment on the field. Methodology/Principal findings The objective of this study was to assess the bactericidal and sterilizing activities of intermittent oral regimens in a murine model of established M. ulcerans infection. Regimens combining rifapentine (RFP 20 mg/kg) with either moxifloxacin (MXF 200 mg/kg), clarithromycin (CLR 100 mg/kg) or bedaquiline (BDQ 25 mg/kg) were administrated twice (2/7) or three (only for RFP-CLR 3/7) times weekly during 8 weeks. The bactericidal but also the sterilizing activities of these four intermittent oral regimens were at least as good as those obtained with control weekdays regimens, i.e. RFP-CLR 5/7 or RIF-STR 5/7. A single mouse from the RFP-MFX 2/7 group had culture-positive relapse at the end of the 28 weeks following treatment completion among the 157 mice treated with one of the four intermittent regimens (40 RFP-CLR 2/7, 39 RFP-CLR 3/7, 39 RFP-MXF 2/7, 39 RFP-BDQ 2/7). Conclusions/Significance These results open the door for a fully intermittent oral drug regimen for BU treatment avoiding intramuscular injections and facilitating supervision by health care workers., Author Summary Buruli ulcer, caused by Mycobacterium ulcerans, is the third most frequent disease due to a bacteria of the mycobacteria family, after tuberculosis and leprosy. The disease consists of a cutaneous infection leading to skin ulcerations that can cause severe and debilitating scars. It occurs mostly in Africa where access to healthcare is still difficult. Until recently, surgery was the only way to treat Buruli ulcer. Recently, a medical treatment based on two antibiotics (rifampin and streptomycin) was found to be active in an experimental infection model and was recommended by WHO in 2004 for humans. A drawback of this new medical approach is a long and daily administration (2 months) of streptomycin, an aminoglycoside, which requires daily injections and can have secondary effects. In our research, we sought to find a fully oral and intermittent treatment to facilitate the management of the patients on the field. The antibiotics combinations we studied were efficient in our model and would need now to be tested on the field.

Combination chemotherapy with rifampin and streptomycin (RIF-STR) for 8 weeks is currently recommended by the WHO as the first-line treatment for Mycobacterium ulcerans infection (Buruli ulcer). To gain better insight into the mode of action of these antibiotics against established M. ulcerans infection foci and to characterize recovery of local immune responses during chemotherapy, we conducted a detailed histopathological study of M. ulcerans -infected and RIF-STR-treated mice. Mice were inoculated with M. ulcerans in the footpad and 11 weeks later treated with RIF-STR. Development of lesions during the first 11 weeks after infection and subsequent differences in disease progression between RIF-STR-treated and untreated mice were studied. Changes in histopathological features, footpad swelling, and number of CFU were analyzed. After inoculation with M. ulcerans , massive infiltrates dominated by polymorphonuclear leukocytes developed at the inoculation site but did not prevent bacterial multiplication. Huge clusters of extracellular bacteria located in large necrotic areas and surrounded by dead leukocytes developed in the untreated mice. Chemotherapy with RIF-STR led to a rapid drop in CFU associated with loss of solid Ziehl-Neelsen staining of acid-fast bacilli. Development of B-lymphocyte clusters and of macrophage accumulations surrounding the mycobacteria demonstrated the resolution of local immune suppression. Results demonstrate that the experimental M. ulcerans mouse infection model will be a valuable tool to investigate efficacy of new treatment regimens and of candidate vaccines.

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.

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.

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.

Background Between 20 and 30 bacteriologically confirmed cases of leprosy are diagnosed each year at the French National Reference Center for mycobacteria. Patients are mainly immigrants from various endemic countries or living in French overseas territories. We aimed at expanding data regarding the geographical distribution of the SNP genotypes of the M. leprae isolates from these patients. Methodology/Principal findings Skin biopsies were obtained from 71 leprosy patients diagnosed between January 2009 and December 2013. Data regarding age, sex and place of birth and residence were also collected. Diagnosis of leprosy was confirmed by microscopic detection of acid-fast bacilli and/or amplification by PCR of the M. leprae-specific RLEP region. Single nucleotide polymorphisms (SNP), present in the M. leprae genome at positions 14 676, 1 642 875 and 2 935 685, were determined with an efficiency of 94% (67/71). Almost all patients were from countries other than France where leprosy is still prevalent (n = 31) or from French overseas territories (n = 36) where leprosy is not totally eradicated, while only a minority (n = 4) was born in metropolitan France but have lived in other countries. SNP type 1 was predominant (n = 33), followed by type 3 (n = 17), type 4 (n = 11) and type 2 (n = 6). SNP types were concordant with those previously reported as prevalent in the patients’ countries of birth. SNP types found in patients born in countries other than France (Comoros, Haiti, Benin, Congo, Sri Lanka) and French overseas territories (French Polynesia, Mayotte and La Réunion) not covered by previous work correlated well with geographical location and history of human settlements. Conclusions/Significance The phylogenic analysis of M. leprae strains isolated in France strongly suggests that French leprosy cases are caused by SNP types that are (a) concordant with the geographic origin or residence of the patients (non-French countries, French overseas territories, metropolitan France) or (b) more likely random in regions where diverse migration flows occurred., Author Summary Leprosy is an old disease that is nearly eradicated from the European continent but not worldwide. The infectious agent, Mycobacterium leprae, has a highly conserved genome, and this property has been used to elucidate the route of its dissemination all over the world. At the French National Reference Center for mycobacteria, 20 to 30 leprosy cases are diagnosed every year, mainly in immigrants from endemic countries or in people living in French overseas territories. A phylogenetic analysis was conducted to investigate the relationship between M. leprae genotypes and the geographical origin of the patients.

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.

International audience; Multidrug resistance, which is acquired by both Gram-positive and Gram-negative bacteria, causes infections that are associated with significant morbidity and mortality in many clinical settings around the world. Because of the rapidly increasing incidence of pathogens that have become resistant to all or nearly all available antibiotics, there is a need for a new generation of antimicrobials with a broad therapeutic range for specific applications against infections. Aedesin is a cecropin-like anti-microbial peptide that was recently isolated from dengue virus-infected salivary glands of the Aedes aegypti mosquito. In the present study, we have refined the analysis of its structural characteristics and have determined its antimicrobial effects against a large panel of multidrug resistant bacterial strains, directly isolated from infected patients. Based the results from nuclear magnetic resonance spectroscopy analysis, Aedesin has a helix-bend-helix structure typical for a member of the family of a-helix anti-microbial peptides. Aedesin efficiently killed Gram-negative bacterial strains that display the most worrisome resistance mechanisms encountered in the clinic, including resistance to carbapenems, aminoglycosides, cephalosporins, 4 th generation fluoroquinolones, folate inhibitors and monobactams. In contrast, Gram-positive strains were insensitive to the lytic effects of the peptide. The anti-bacterial activity of Aedesin was found to be salt-resistant, indicating that it is active under physiological conditions encountered in body fluids characterized by ionic salt concentrations. In conclusion, because of its strong lytic activity against multidrug resistant Gram-negative bacterial strains displaying all types of clinically relevant resistance mechanisms known today, Aedesin might be an interesting candidate for the development of alternative treatment for infections caused by these types of bacteria.

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.

It has been shown previously that fluoroquinolone resistance (defined by resistance to at least 2 mg/liter ofloxacin) has a different impact on moxifloxacin monotherapy depending on the mutation in the sole fluoroquinolone target in Mycobacterium tuberculosis , i.e., DNA gyrase. Since tuberculosis treatment relies on multidrug therapy, we wished to determine the impact of fluoroquinolone resistance on the bactericidal and sterilizing activity of a second-line antituberculous regimen containing moxifloxacin. A total of 280 mice were inoculated with the wild-type Mycobacterium tuberculosis H37Rv strain or one of 3 isogenic fluoroquinolone-resistant mutant strains with increasing moxifloxacin resistance (the GyrB D500N, GyrA A90V, and GyrA D94G strains) and then treated for 6 months with a second-line regimen containing moxifloxacin, pyrazinamide, and ethionamide supplemented with amikacin during the first 2 months. Mice were sacrificed during treatment for measurement of bactericidal activity and 3 months after treatment completion for measurement of relapse rates (sterilizing activity). The CFU counts decreased faster in mice inoculated with the wild type than in mice inoculated with the mutant strains. The relapse rate after treatment completion was different among mice inoculated with mutant strains in relation to the drug resistance level: wild type, 0%; GyrB D500N strain, 33%; GyrA A90V strain, 50%; and GyrA D94G strain, 86%. The relapse rate observed with the GyrB D500N strain was the only one not statistically different from that observed with the wild-type strain. We demonstrated that the impact on sterilizing activity of the most active second-line drug regimen containing moxifloxacin depends on the MIC of moxifloxacin. We suggest that the precise level of moxifloxacin resistance be determined for all strains resistant to 2 mg/liter ofloxacin.

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-Foxn1nu/Foxn1nu) were inoculated in the left hind footpad with 0.03 ml of bacterial suspension containing 5×103, 5×102, 5×101, and 5×100 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., Author Summary Although there is efficient multidrug therapy to cure leprosy, the transmission of M. leprae is still active, leading to 219,000 new cases in 2011. Drug resistant leprosy has been described and may prevent eradication of the disease, notably multidrug resistant defined as resistance to rifampin, dapsone and fluoroquinolones (FQ). Resistance to FQ is due to mutations in DNA gyrase. We used a mouse model to measure the impact of DNA gyrase mutations on in vivo FQ activity. All the FQ tested showed in vivo activity against the mutant tested (A91V mutant in subunit A of DNA gyrase). However, whereas ofloxacin was less active than the control treatment clarithromycin, it appeared that latter generation fluoroquinolones moxifloxacin and garenoxacin were as active as clarithromycin. Our results demonstrate that DNA gyrase mutation is not synonymous of total lack of in vivo FQ activity against M. leprae. Therefore, as for M. tuberculosis, in vivo studies are mandatory in order to measure the impact of DNA gyrase mutations on treatment efficacy against M. leprae.

Because of operational limitations, a significant proportion of the health centers at the peripheral level are able to provide treatment to Buruli ulcer patients with the combination rifampin (rifampicin)-streptomycin (RIF-STR) only five times weekly (5/7) instead of seven times weekly (7/7), as recommended. The objective of this experiment is to assess the impacts of various dosing frequencies of the combination on its bactericidal and sterilizing activities against Mycobacterium ulcerans in mice. The results demonstrate that the bactericidal activities did not differ significantly among five dosing frequencies of the combination, ranging from seven times to twice weekly, whereas the sterilizing activities differed widely. RIF-STR 7/7 was the only regimen that was able to sterilize the infection after 4 to 8 weeks of treatment; the sterilizing activities associated with reduced dosing frequencies were significantly diminished, and 8 weeks of 5/7 administration yielded a relapse rate greater than the generally accepted level of 5%. We recommend that the duration of treatment with 5/7 administration be prolonged beyond 8 weeks and that additional experiments with mice be carried out, with sufficient statistical power to compare the relapse rates of M. ulcerans infection between 8 weeks of 7/7 administration and 10 and 12 weeks of 5/7 administration of RIF-STR.

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 log10 for rifapentine and by 5 to 6 log10 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.

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 log 10 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.

Seven antimicrobials were tested in vitro against 29 clinical isolates of Mycobacterium ulcerans . R207910 demonstrated the lowest MIC 50 and MIC 90 , followed by moxifloxacin (MXF), streptomycin (STR), rifampin (RIF), amikacin (AMK), linezolid (LZD), and PA-824. All but PA-824 demonstrated an MIC 90 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.

Long-half-life drugs raise the hope of once-a-week administration of antituberculous treatment. In a previous study with the murine model of tuberculosis, the most active intermittent regimen which contained rifapentine (RFP), isoniazid (INH), and moxifloxacin (MXF) given once a week during 5.5 months, preceded by 2 weeks of daily treatment with INH, rifampin (RIF), pyrazinamide (PZA), and MXF, was less active than the standard 6-month daily RIF-INH-PZA regimen. We evaluated with the same model similar regimens in which we increased the dosing of rifapentine from 10 to 15 mg/kg of body weight and of moxifloxacin from 100 to 400 mg/kg. Mice infected intravenously by 6.2 ×10 6 CFU of Mycobacterium tuberculosis H37Rv were treated 2 weeks later when infection was established. After 6 months of treatment, all mice had negative lung culture. After 3 months of follow-up, no relapse occurred in the two groups that received moxifloxacin at 400 mg/kg, whatever the dosage of RFP, and in the group receiving the standard RIF-INH-PZA control regimen. In contrast, in the two groups receiving moxifloxacin at a lower dosage, the relapse rate was significantly higher (13% in mice receiving RFP at 15 mg/kg and 27% in those receiving RFP at 10 mg/kg). Finally, the fully intermittent once-a-week regimen (26 drug ingestions) of INH, RFP (15 mg/kg), and MXF (400 mg/kg) led to a relapse rate of 11%. In conclusion, when used at high dosage, rifapentine and moxifloxacin are very efficient when combined with isoniazid in a once-a-week treatment in mouse tuberculosis.

Objectives: Antimicrobial resistance (AMR) is a priority for surveillance in bacterial infections. For leprosy, AMR has not been assessed because Mycobacterium leprae does not grow in vitro. We aim to obtain AMR data using molecular detection of resistance genes and to conduct a prospective open survey of resistance to antileprosy drugs in countries where leprosy is endemic through a WHO surveillance network., Methods: From 2009 to 2015, multi-bacillary leprosy cases at sentinel sites of 19 countries were studied for resistance to rifampicin, dapsone and ofloxacin by PCR sequencing of the drug-resistance-determining regions of the genes rpoB, folP1 and gyrA., Results: Among 1932 (1143 relapse and 789 new) cases studied, 154 (8.0%) M. leprae strains were found with mutations conferring resistance showing 182 resistance traits (74 for rifampicin, 87 for dapsone and 21 for ofloxacin). Twenty cases showed rifampicin and dapsone resistance, four showed ofloxacin and dapsone resistance, but no cases were resistant to rifampicin and ofloxacin. Rifampicin resistance was observed among relapse (58/1143, 5.1%) and new (16/789, 2.0%) cases in 12 countries. India, Brazil and Colombia reported more than five rifampicin-resistant cases., Conclusions: This is the first study reporting global data on AMR in leprosy. Rifampicin resistance emerged, stressing the need for expansion of surveillance. This is also a call for vigilance on the global use of antimicrobial agents, because ofloxacin resistance probably developed in relation to the general intake of antibiotics for other infections as it is not part of the multidrug combination used to treat leprosy. (C) 2018 The Authors. Published by Elsevier Ltd on behalf of European Society of Clinical Microbiology and Infectious Diseases.