Moxifloxacin-containing Regimens Research Articles

Optimizing tuberculosis treatment efficacy: Comparing the standard regimen with Moxifloxacin-containing regimens.

Tuberculosis (TB) continues to be one of the deadliest infectious diseases in the world, causing ~1.5 million deaths every year. The World Health Organization initiated an End TB Strategy that aims to reduce TB-related deaths in 2035 by 95%. Recent research goals have focused on discovering more effective and more patient-friendly antibiotic drug regimens to increase patient compliance and decrease emergence of resistant TB. Moxifloxacin is one promising antibiotic that may improve the current standard regimen by shortening treatment time. Clinical trials and in vivo mouse studies suggest that regimens containing moxifloxacin have better bactericidal activity. However, testing every possible combination regimen with moxifloxacin either in vivo or clinically is not feasible due to experimental and clinical limitations. To identify better regimens more systematically, we simulated pharmacokinetics/pharmacodynamics of various regimens (with and without moxifloxacin) to evaluate efficacies, and then compared our predictions to both clinical trials and nonhuman primate studies performed herein. We used GranSim, our well-established hybrid agent-based model that simulates granuloma formation and antibiotic treatment, for this task. In addition, we established a multiple-objective optimization pipeline using GranSim to discover optimized regimens based on treatment objectives of interest, i.e., minimizing total drug dosage and lowering time needed to sterilize granulomas. Our approach can efficiently test many regimens and successfully identify optimal regimens to inform pre-clinical studies or clinical trials and ultimately accelerate the TB regimen discovery process.

Altered drug exposures of first-line TB drugs in a moxifloxacin-containing treatment regimen.

BACKGROUND: Pharmacokinetic variability arising from drug-drug interactions and pharmacogenetics may influence the effectiveness of treatment regimens for TB. The Improving Treatment Success Trial compared the WHO-recommended standard treatment in TB patients with an experimental regimen substituting ethambutol with moxifloxacin (MFX) in Durban, South Africa.METHODS: Non-linear mixed-effects modelling was used to investigate the population pharmacokinetics of rifampicin (RIF), isoniazid (INH) and pyrazinamide (PZA). A total of 25 single-nucleotide polymorphisms, including pregnane-X-receptor, were selected for analysis.RESULTS: TB drug concentrations were available in a subset of 101 patients: 58 in the MFX arm and 43 in the control arm. Baseline characteristics were well-balanced between study arms: median age and weight were respectively 36 years and 57.7 kg; 75.2% of the patients were living with HIV. Although weight-based drug dosing was the same in the two arms, we found that RIF exposure was increased by 19.3%, INH decreased by 19% and PZA decreased by 19.2% when administered as part of the MFX-containing regimen. Genetic variation in pregnane-X-receptor (rs2472677) was associated with a 25.3% reduction in RIF exposure.CONCLUSION: Optimised weight-based TB treatment dosing is essential when RIF, INH and PZA are co-administered with fluoroquinolones. The reduction in RIF exposure associated with pharmacogenetic variation is worrying.

Shortened treatment regimens versus the standard regimen for drug-sensitive pulmonary tuberculosis.

Shortened treatment regimens versus the standard regimen for drug-sensitive pulmonary tuberculosis.

A Moxifloxacin-based Regimen for the Treatment of Recurrent, Drug-sensitive Pulmonary Tuberculosis: An Open-label, Randomized, Controlled Trial.

The substitution of moxifloxacin for ethambutol produced promising results for improved tuberculosis treatment outcomes. We conducted an open-label, randomized trial to test whether a moxifloxacin-containing treatment regimen was superior to the standard regimen for the treatment of recurrent tuberculosis. The primary and secondary outcomes were the sputum culture conversion rate at the end of 8 weeks and the proportion of participants with a favorable outcome, respectively. We enrolled 196 participants; 69.9% were male and 70.4% were co-infected with human immunodeficiency virus (HIV). There was no significant difference between the study groups in the proportion of patients achieving culture conversion at the end of 8 weeks (83.0% [moxifloxacin] vs 78.5% [control]; P = .463); however, the median time to culture conversion was significantly shorter (6.0 weeks, interquartile range [IQR] 4.0-8.3) in the moxifloxacin group than the control group (7.9 weeks, IQR 4.0- 11.4; P = .018). A favorable end-of-treatment outcome was reported in 86 participants (87.8%) in the moxifloxacin group and 93 participants (94.9%) in the control group, for an adjusted absolute risk difference of -5.5 (95% confidence interval -13.8 to 2.8; P = .193) percentage points. There were significantly higher proportions of participants with Grade 3 or 4 adverse events (43.9% [43/98] vs 25.5% [25/98]; P = .01) and serious adverse events (27.6% [27/98] vs 12.2% [12/98]; P = .012) in the moxifloxacin group. The replacement of ethambutol with moxifloxacin did not significantly improve either culture conversion rates at the end of 8 weeks or treatment success, and was associated with a higher incidence of adverse events. NCT02114684.

Safety and tolerability of moxifloxacin for the treatment of disseminated BCGitis in children.

Background and objectiveDisseminated BCGitis is a rare but serious complication of BCG vaccine in patients with underlying primary immunodeficiency. Fluoroquinolone antibiotics containing antimycobacterial regimen have been considered in the treatment of disseminated BCGitis, but there are limited data about the dosing, safety, and tolerability of fluoroquinolone such as moxifloxacin in children. The aim of this study was to report the experience with the dosing, safety, and tolerability of moxifloxacin in children with disseminated BCGitis.MethodThis retrospective descriptive study included children who had been diagnosed with disseminated BCGitis and treated with an antimycobacterial regimen including moxifloxacin for more than two weeks from 2007 to 2017 at King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia.ResultTen children were included: six (60.0%) were male and four (40.0%) were female. The primary diagnosis for five patients was Mendelian susceptibility to mycobacterial diseases (MSMD), four patients were diagnosed with severe combined immune deficiency (SCID), and the remaining patient had human immunodeficiency virus (HIV) infection. The overall mean duration of moxifloxacin treatment was 10.1 months. Liver toxicity was recorded in three patients. The most common medications used with moxifloxacin were ethambutol and clarithromycin. Moxifloxacin serum concentration level was determined in 5 patients. No musculoskeletal side effects were reported while the patient was on moxifloxacin. The treated patients showed a different response to an antimycobacterial regimen including moxifloxacin, with mortality in two patients.ConclusionOur study suggests that moxifloxacin is generally tolerated in children and might be considered in disseminated BCGitis cases. Additionally, paying attention to side effects such as liver toxicity is recommended, particularly with the use of other antimycobacterial antibiotics, which could also be hepatotoxic. A moxifloxacin-containing regimen for disseminated BCGitis showed clinical improvement in some patients in this study, although the majority presented the same clinical condition.

Gender differences in tuberculosis treatment outcomes: a post hoc analysis of the REMoxTB study

BackgroundIn the REMoxTB study of 4-month treatment-shortening regimens containing moxifloxacin compared to the standard 6-month regimen for tuberculosis, the proportion of unfavourable outcomes for women was similar in all study arms, but men had more frequent unfavourable outcomes (bacteriologically or clinically defined failure or relapse within 18 months after randomisation) on the shortened moxifloxacin-containing regimens. The reason for this gender disparity in treatment outcome is poorly understood.MethodsThe gender differences in baseline variables were calculated, as was time to smear and culture conversion and Kaplan-Meier plots were constructed. In post hoc exploratory analyses, multivariable logistic regression modelling and an observed case analysis were used to explore factors associated with both gender and unfavourable treatment outcome.ResultsThe per-protocol population included 472/1548 (30%) women. Women were younger and had lower rates of cavitation, smoking and weight (all p < 0.05) and higher prevalence of HIV (10% vs 6%, p = 0.001). They received higher doses (mg/kg) than men of rifampicin, isoniazid, pyrazinamide and moxifloxacin (p ≤ 0.005). There was no difference in baseline smear grading or mycobacterial growth indicator tube (MGIT) time to positivity. Women converted to negative cultures more quickly than men on Lowenstein-Jensen (HR 1.14, p = 0.008) and MGIT media (HR 1.19, p < 0.001). In men, the presence of cavitation, positive HIV status, higher age, lower BMI and ‘ever smoked’ were independently associated with unfavourable treatment outcome. In women, only ‘ever smoked’ was independently associated with unfavourable treatment outcome. Only for cavitation was there a gender difference in treatment outcomes by regimen; their outcome in the 4-month arms was significantly poorer compared to the 6-month treatment arm (p < 0.001). Women, with or without cavities, and men without cavities had a similar outcome on all treatment arms (p = 0.218, 0.224 and 0.689 respectively). For all other covariate subgroups, there were no differences in treatment effects for men or women.ConclusionsGender differences in TB treatment responses for the shorter regimens in the REMoxTB study may be explained by poor outcomes in men with cavitation on the moxifloxacin-containing regimens. We observed that women with cavities, or without, on the 4-month moxifloxacin regimens had similar outcomes to all patients on the standard 6-month treatment. The biological reasons for this difference are poorly understood and require further exploration.

Shortened treatment regimens versus the standard regimen for drug-sensitive pulmonary tuberculosis

Shortened treatment regimens versus the standard regimen for drug-sensitive pulmonary tuberculosis

Effects of Fluroquinolones in Newly Diagnosed, Sputum-Positive Tuberculosis Therapy: A Systematic Review and Network Meta-Analysis.

BackgroundTuberculosis is a major public health problem especially in developing countries, the comparative efficacy and safety of fluroquinolones (FQs) for adult patients with newly diagnosed, sputum-positive tuberculosis remains controversial. We aimed to investigate the benefits and risks of FQs-containing (addition/substitution) regimens in this population.MethodsA network meta-analysis was performed to compare FQs (C: ciprofloxacin; O: ofloxacin; Lo: levofloxacin; M: moxifloxacin; G: gatifloxacin) addition/substitution regimen with standard HRZE regimen (ie isoniazid, rifampicin, pyrazinamide and ethambutol) in newly diagnosed, sputum-positive tuberculosis. Medline, Embase and Cochrane Central Register of Controlled Trials were systematically searched, randomized trials with duration longer than 8 weeks were included. The primary outcome was week-8 sputum negativity, and secondary outcomes included treatment failure, serious adverse events and death from all cause.ResultsTwelve studies comprising 6465 participants were included in the network meta-analysis. Löwenstein-Jensen culture method showed that HRZEM (OR 4.96, 95% CI 2.83–8.67), MRZE (OR 1.48, 95% CI 1.19–1.84) and HRZM (OR 1.32, 95% CI 1.08–1.62) had more sputum conversion than HRZE by the eighth week, whereas HRC (OR 0.39, 95% CI 0.19–0.77) and HRZO (OR 0.47, 95% CI 0.24–0.92) were worse than HRZE. Moxifloxacin-containing regimens showed more conversion than HRZE by liquid method at the end of two months. But by the end of treatment, FQs-containing regimens didn’t show superiority than HRZE on treatment failure. There were no significant differences between any regimens on other outcomes like serious adverse events and all-cause death.ConclusionThis comprehensive network meta-analysis showed that compared with HRZE, moxifloxacin-containing regimens could significantly increase sputum conversion by the eighth week for patients with newly diagnosed pulmonary tuberculosis while HRC and HRZO regimens were inferior. But all the FQs-containing regimens did not show superiority in other outcomes (such as treatment failure, serious adverse events and all-cause death). Thus, HRZE is still an effective regimen for this population. Although moxifloxacin-containing regimens have deomonstrated their potential, FQs-containing regimens should be used with great caution to avoid widespread FQs-resistance worldwide.

Evaluation of moxifloxacin-containing regimens in pathologically distinct murine tuberculosis models.

In the recently concluded REMox-TB trial, two 4-month moxifloxacin-containing regimens did not meet the criteria for noninferiority compared to the current 6-month first-line regimen to treat tuberculosis (TB). Despite the disappointing result, this phase 3 clinical trial provides a rare opportunity to gauge the predictive accuracy of the nonclinical models used to support regimen development. In parallel with the REMox-TB trial, we compared the efficacy of the same three regimens against chronic TB infection in the commonly used BALB/c mouse strain and in C3HeB/FeJ mice, which have attracted recent interest as a nonclinical efficacy model because they develop caseous lung lesions which may better resemble human TB. In long-term treatment experiments at two institutions, using low-dose aerosol infection models with 6- to 8-week incubation periods in both mouse strains, control mice received rifampin, isoniazid, pyrazinamide, and ethambutol (RHZE), and test mice received the same regimen with moxifloxacin replacing isoniazid (RMZE) or ethambutol (RHZM). Outcome measures were lung CFU counts during treatment and relapse after various durations of treatment. At both institutions and in both mouse strains, RMZE and RHZM reduced by approximately 1 month and 0 to 1 month, respectively, the treatment duration needed to produce the same relapse rate as RHZE. These results demonstrating generally similar treatment-shortening effects of the moxifloxacin-containing regimens in each mouse strain, with effect sizes consistent with the REMox-TB trial results, reinforce the predictive value of murine models for TB regimen development.

Shorter moxifloxacin-based regimens for drug-sensitive tuberculosis

To the Editor: Gillespie et al. (Oct. 23 issue)1 report that two moxifloxacin-containing regimens for the treatment of tuberculosis were not effective with a shortened treatment period of 4 months. The authors used a moxifloxacin dose of 400 mg per day, which may have contributed to the unfavorable results. Rifampin decreases the average exposure to moxifloxacin (assessed according to the area under the curve [AUC]) by approximately 30%,2 which can be compensated for by an increase in the dose of moxifloxacin.3 In addition, preclinical data combined with pharmacokinetic and pharmacodynamic modeling showed that a higher moxifloxacin dose, of 800 mg per day, is likely to achieve better Mycobacterium tuberculosis microbial killing and suppression of drug resistance.4 Limited data have shown that moxifloxacin at a dose of 800 mg can be given safely.3,5 The inclusion of moxifloxacin drug exposure as a covariate would have been of additional value, considering that the ratio of the AUC to the minimum inhibitory concentration is the driver of moxifloxacin efficacy and that the AUC for moxifloxacin can vary among patients by a factor of 7.6 Such a pharmacokinetic and pharmacodynamic analysis could have shown whether the results of this trial could have been explained by a drug exposure to moxifloxacin that was too low.

Four-Month Moxifloxacin-Based Regimens for Drug-Sensitive Tuberculosis

BackgroundEarly-phase and preclinical studies suggest that moxifloxacin-containing regimens could allow for effective 4-month treatment of uncomplicated, smear-positive pulmonary tuberculosis.MethodsWe conducted a randomized, double-blind, placebo-controlled, phase 3 trial to test the noninferiority of two moxifloxacin-containing regimens as compared with a control regimen. One group of patients received isoniazid, rifampin, pyrazinamide, and ethambutol for 8 weeks, followed by 18 weeks of isoniazid and rifampin (control group). In the second group, we replaced ethambutol with moxifloxacin for 17 weeks, followed by 9 weeks of placebo (isoniazid group), and in the third group, we replaced isoniazid with moxifloxacin for 17 weeks, followed by 9 weeks of placebo (ethambutol group). The primary end point was treatment failure or relapse within 18 months after randomization.ResultsOf the 1931 patients who underwent randomization, in the per-protocol analysis, a favorable outcome was reported in fewer patients in the isoniazid group (85%) and the ethambutol group (80%) than in the control group (92%), for a difference favoring the control group of 6.1 percentage points (97.5% confidence interval [CI], 1.7 to 10.5) versus the isoniazid group and 11.4 percentage points (97.5% CI, 6.7 to 16.1) versus the ethambutol group. Results were consistent in the modified intention-to-treat analysis and all sensitivity analyses. The hazard ratios for the time to culture negativity in both solid and liquid mediums for the isoniazid and ethambutol groups, as compared with the control group, ranged from 1.17 to 1.25, indicating a shorter duration, with the lower bounds of the 95% confidence intervals exceeding 1.00 in all cases. There was no significant difference in the incidence of grade 3 or 4 adverse events, with events reported in 127 patients (19%) in the isoniazid group, 111 (17%) in the ethambutol group, and 123 (19%) in the control group.ConclusionsThe two moxifloxacin-containing regimens produced a more rapid initial decline in bacterial load, as compared with the control group. However, noninferiority for these regimens was not shown, which indicates that shortening treatment to 4 months was not effective in this setting. (Funded by the Global Alliance for TB Drug Development and others; REMoxTB ClinicalTrials.gov number, NCT00864383.)

Sputum culture conversion with moxifloxacin-containing regimens in the treatment of patients with newly diagnosed sputum-positive pulmonary tuberculosis in South India.

Rapid sputum culture conversion at 2 months indicates the sterilizing capacity and potential of regimens to shorten duration of tuberculosis treatment. We compared results of sputum culture conversion by moxifloxacin and control regimens and identified factors affecting sputum culture positivity after 2 months of treatment. Human immunodeficiency virus-uninfected adults with newly diagnosed smear-positive pulmonary tuberculosis were randomized to receive a 3- or 4-month moxifloxacin regimen (moxifloxacin [M], isoniazid [H], rifampicin [R], pyrazinamide [Z], ethambutol [E]) or the control regimen (RHZE thrice weekly). Bacteriological assessments were done at 15, 30, 45, and 60 days of treatment. Because all patients in the moxifloxacin groups received 2 months of daily RHZEM, they were grouped together for analysis. Statistical methods included χ(2) test and logistic regression analysis. Sputum culture conversion was analyzed in 780 (616 in the moxifloxacin group and 164 in the control group) of 801 enrolled patients. Ninety-five percent of 590 patients in the moxifloxacin group and 81% of 151 patients in the control group had negative sputum cultures at month 2 (P < .001). The control regimen, age (≥35 years), initial sputum culture grade (2+ or 3+), and male sex were significantly associated with higher odds of positive sputum cultures at 2 months. A 5-drug daily regimen with moxifloxacin results in significantly higher sputum culture conversion in the first 2 months compared with a thrice-weekly, 4-drug regimen in patients with newly diagnosed sputum-positive pulmonary tuberculosis.

Respiratory review of 2014: tuberculosis and nontuberculous mycobacterial pulmonary disease.

Since tuberculosis (TB) remains a major global health concern and the incidence of multi-drug resistant (MDR)-TB is increasing globally, new modalities for the detection of TB and drug resistant TB are needed to improve TB control. The Xpert MTB/RIF test can be a valuable new tool for early detection of TB and rifampicin resistance, with a high sensitivity and specificity. Late-generation fluoroquinolones, levofloxacin, and moxifloxacin, which are the principal drugs for the treatment of MDR-TB, show equally high efficacy and safety. Systemic steroids may reduce the overall TB mortality attributable to all forms of TB across all organ systems, although inhaled corticosteroids can increase the risk of TB development. Although fixed dose combinations were expected to reduce the risk of drug resistance and increase drug compliance, a recent meta-analysis found that they might actually increase the risk of relapse and treatment failure. Regarding treatment duration, patients with cavitation and culture positivity at 2 months of TB treatment may require more than 6 months of standard treatment. New anti-TB drugs, such as linezolid, bedaquiline, and delamanid, could improve the outcomes in drug-resistant TB. Nontuberculous mycobacterial lung disease has typical clinical and immunological phenotypes. Mycobacterial genotyping may predict disease progression, and whole genome sequencing may reveal the transmission of Mycobacterium abscessus. In refractory Mycobacterium avium complex lung disease, a moxifloxacin-containing regimen was expected to improve the treatment outcome.

Impact of fluoroquinolone resistance on bactericidal and sterilizing activity of a moxifloxacin-containing regimen in murine tuberculosis

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.

Month 2 Culture Status and Treatment Duration as Predictors of Tuberculosis Relapse Risk in a Meta-Regression Model

BackgroundNew drugs and regimens with the potential to transform tuberculosis treatment are presently in early stage clinical trials.ObjectiveThe goal of the present study was to infer the required duration of these treatments.MethodA meta-regression model was developed to predict relapse risk using treatment duration and month 2 sputum culture positive rate as predictors, based on published historical data from 24 studies describing 58 regimens in 7793 patients. Regimens in which rifampin was administered for the first 2 months but not subsequently were excluded. The model treated study as a random effect.ResultsThe model predicted that new regimens of 4 or 5 months duration with rates of culture positivity after 2 months of 1% or 3%, would yield relapse rates of 4.0% or 4.1%, respectively. In both cases, the upper limit of the 2-sided 80% prediction interval for relapse for a hypothetical trial with 680 subjects per arm was <10%. Analysis using this model of published month 2 data for moxifloxacin-containing regimens indicated they would result in relapse rates similar to standard therapy only if administered for ≥5 months.ConclusionsThis model is proposed to inform the required duration of treatment of new TB regimens, potentially hastening their accelerated approval by several years.

Impact of Fluoroquinolone Resistance on Bactericidal and Sterilizing Activity of a Moxifloxacin-Containing Regimen in Murine Tuberculosis

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.

Treatment of Refractory Mycobacterium avium Complex Lung Disease with a Moxifloxacin-Containing Regimen

Moxifloxacin (MXF) has in vitro and in vivo activity against Mycobacterium avium complex (MAC) in experimental models. However, no data are available concerning its treatment effect in patients with MAC lung disease. The aim of this study was to evaluate the clinical efficacy of an MXF-containing regimen for the treatment of refractory MAC lung disease. Patients with MAC lung disease who were diagnosed between January 2002 and December 2011 were identified from our hospital database. We identified 41 patients who received MXF for ≥ 4 weeks for the treatment of refractory MAC lung disease. A total of 41 patients were treated with an MXF-containing regimen because of a persistent positive culture after at least 6 months of clarithromycin-based standardized antibiotic therapy. The median duration of antibiotic therapy before MXF administration was 410 days (interquartile range [IQR], 324 to 683 days). All patients had culture-positive sputum when MXF treatment was initiated. The median duration of MXF administration was 332 days (IQR, 146 to 547 days). The overall treatment success rate was 29% (12/41), and the median time to sputum conversion was 91 days (IQR, 45 to 190 days). A positive sputum acid-fast-bacillus smear at the start of treatment with MXF-containing regimens was an independent predictor of an unfavorable microbiological response. Our results indicate that MXF may improve treatment outcomes in about one-third of patients with persistently culture-positive MAC lung disease who fail to respond to clarithromycin-based standardized antibiotic treatment. Prospective studies are required to assess the clinical efficacy of MXF treatment for refractory MAC lung disease.

Moxifloxacin for the treatment of pulmonary tuberculosis in children: A single center experience

To report our experience on the safety and tolerability of moxifloxacin for treating children affected by pulmonary TB. Children receiving a moxifloxacin-containing anti-TB regimen were included in the study. Their medical records were revised at the end of follow-up. We describe nine children treated with moxifloxacin for pulmonary TB at Regina Margherita Children's Hospital (Turin, Italy) between 2007 and 2012. Moxifloxacin was administered orally at 10 mg/kg/day once daily (maximum dose = 400 mg/day) following World Health Organization indications. During treatment, patients were systematically assessed for the development of side effects. Eight children were considered cured at the end of treatment; one child was lost to follow-up after 3 months of treatment. Two children had side effects during treatment: one developed arthritis of the ankle; the other had liver toxicity, whose relationship with moxifloxacin could not be ruled out. We did not observe any case of QT prolongation, central nervous system disorders, growth defects or gastrointestinal disturbances. A moxifloxacin-containing regimen might be considered for the treatment of TB in children, especially for drug-resistant and extensive forms. However, vigilance for possible side effects is recommended, especially if other drugs are concomitantly used. Studies on wider populations are needed to better define the impact of long-term treatments with quinolones on children's growth and psychomotor development and to outline regulatory indications on moxifloxacin use in the pediatric setting.

Moxifloxacin for tuberculosis

We believe Helen Cox and colleagues’ proposal to restrict moxifl oxacin use to multidrug-resistant tuberculosis is based on fl awed logic. In a clinical trial of the present fi rst-line regimen for drug-susceptible tuberculosis, cure rates were greater than 95% and no new regimen is likely to improve on this rate. However, reducing treatment duration with moxifl oxacincontaining regimens would lead to a decreased risk of default and consequent drug resistance. Moxifl oxacin-containing regimens render sputum cultures sterile more rapidly than standard therapy, and so reduce onward transmission. A resultant decline in incident cases has been estimated by modelling studies. Cox and colleagues suggest that reserving moxifl oxacin for use in drugresistant tuberculosis will decrease future drug resistance. Restriction might be feasible in government programmes but is unrealistic in private practice, which is a common setting for tuberculosis treatment in countries with a high tuberculosis burden, including India. Furthermore, that all drugs in this class can be restricted is unlikely because of their widespread use and low cost. Those drugs with poorer anti-tuberculosis activity are more likely to select for resistance—for example, exposure to subinhibitory ciprofl oxacin concentrations increased mycobacterial mutation rates by up to 200 times compared with the rates without the antibiotic. Cross-resistance among fl uoroquinolones is common. Therefore, restriction of one drug in the class would not achieve a useful result. Cox and colleagues note that treatment-shortening trials are underway, and we advocate that patients with uncomplicated susceptible disease should not be treated with moxifl oxacin until results of these trials are known. In cases of drug resistance or poor tolerance, fl uoroquinolones should be used only in settings where susceptibility results are available to prevent the risk of increasing resistance.

Tolerance of moxifloxacin-containing regimens in the treatment of tuberculosis [Correspondence

Tolerance of moxifloxacin-containing regimens in the treatment of tuberculosis [Correspondence