FAST tuberculosis transmission control strategy speeds the start of tuberculosis treatment at a general hospital in Lima, Peru.

OBJECTIVE: To evaluate the effect of the FAST (Find cases Actively, Separate safely, Treat effectively) strategy on time to tuberculosis diagnosis and treatment for patients at a general hospital in a tuberculosis-endemic setting. DESIGN: Prospective cohort study with historical controls. PARTICIPANTS: Patients diagnosed with pulmonary tuberculosis during hospitalization at Hospital Nacional Hipolito Unanue in Lima, Peru. METHODS: The FAST strategy was implemented from July 24, 2016, to December 31, 2019. We compared the proportion of patients with drug susceptibility testing and tuberculosis treatment during FAST to the 6-month period prior to FAST. Times to diagnosis and tuberculosis treatment were also compared using Kaplan-Meier plots and Cox regressions. RESULTS: We analyzed 75 patients diagnosed with pulmonary tuberculosis through FAST. The historical cohort comprised 76 patients. More FAST patients underwent drug susceptibility testing (98.7% vs 57.8%; OR, 53.8; P < .001), which led to the diagnosis of drug-resistant tuberculosis in 18 (24.3%) of 74 of the prospective cohort and 4 (9%) of 44 of the historical cohort (OR, 3.2; P = .03). Overall, 55 FAST patients (73.3%) started tuberculosis treatment during hospitalization compared to 39 (51.3%) controls (OR, 2.44; P = .012). FAST reduced the time from hospital admission to the start of TB treatment (HR, 2.11; 95% CI, 1.39-3.21; P < .001). CONCLUSIONS: Using the FAST strategy improved the diagnosis of drug-resistant tuberculosis and the likelihood and speed of starting treatment among patients with pulmonary tuberculosis at a general hospital in a tuberculosis-endemic setting. In these settings, the FAST strategy should be considered to reduce tuberculosis transmission while simultaneously improving the quality of care.

An optimized background regimen design to evaluate the contribution of levofloxacin to multidrug-resistant tuberculosis treatment regimens: study protocol for a randomized controlled trial.

BACKGROUND: Current guidelines for treatment of multidrug-resistant tuberculosis (MDR-TB) are largely based on expert opinion and observational data. Fluoroquinolones remain an essential part of MDR-TB treatment, but the optimal dose of fluoroquinolones as part of the regimen has not been defined. METHODS/DESIGN: We designed a randomized, blinded, phase II trial in MDR-TB patients comparing across levofloxacin doses of 11, 14, 17 and 20 mg/kg/day, all within an optimized background regimen. We assess pharmacokinetics, efficacy, safety and tolerability of regimens containing each of these doses. The primary efficacy outcome is time to culture conversion over the first 6 months of treatment. The study aims to determine the area under the curve (AUC) of the levofloxacin serum concentration in the 24 hours after dosing divided by the minimal inhibitory concentration of the patient's Mycobacterium tuberculosis isolate that inhibits > 90% of organisms (AUC/MIC) that maximizes efficacy and the AUC that maximizes safety and tolerability in the context of an MDR-TB treatment regimen. DISCUSSION: Fluoroquinolones are an integral part of recommended MDR-TB regimens. Little is known about how to optimize dosing for efficacy while maintaining acceptable toxicity. This study will provide evidence to support revised dosing guidelines for the use of levofloxacin as part of combination regimens for treatment of MDR-TB. The novel methodology can be adapted to elucidate the effect of other single agents in multidrug antibiotic treatment regimens. TRIAL REGISTRATION: ClinicalTrials.gov, NCT01918397 . Registered on 5 August 2013.

Fluoroquinolone Resistance Mutation Detection Is Equivalent to Culture-Based Drug Sensitivity Testing for Predicting Multidrug-Resistant Tuberculosis Treatment Outcome: A Retrospective Cohort Study.

BACKGROUND: Molecular diagnostics that rapidly and accurately predict fluoroquinolone (FQ) resistance promise to improve treatment outcomes for individuals with multidrug-resistant (MDR) tuberculosis (TB). Mutations in the gyr genes, though, can cause variable levels of in vitro FQ resistance, and some in vitro resistance remains unexplained by gyr mutations alone, but the implications of these discrepancies for treatment outcome are unknown. METHODS: We performed a retrospective cohort study of 172 subjects with MDR/extensively drug-resistant TB subjects and sequenced the full gyrA and gyrB open reading frames in their respective sputum TB isolates. The gyr mutations were classified into 2 categories: a set of mutations that encode high-level FQ resistance and a second set that encodes intermediate resistance levels. We constructed a Cox proportional model to assess the effect of the gyr mutation type on the time to death or treatment failure and compared this with in vitro FQ resistance, controlling for host and treatment factors. RESULTS: Controlling for other host and treatment factors and compared with patients with isolates without gyr resistance mutations, "high-level" gyr mutations significantly predict poor treatment outcomes with a hazard ratio of 2.6 (1.2-5.6). We observed a hazard of death and treatment failure with "intermediate-level" gyr mutations of 1.3 (0.6-3.1), which did not reach statistical significance. The gyr mutations were not different than culture-based FQ drug susceptibility testing in predicting the hazard of death or treatment failure and may be superior. CONCLUSIONS: FQ molecular-based diagnostic tests may better predict treatment response than traditional drug susceptibility testing and open avenues for personalizing TB therapy.

Second line drug susceptibility testing to inform the treatment of rifampin-resistant tuberculosis: a quantitative perspective.

Treatment failure and resistance amplification are common among patients with rifampin-resistant tuberculosis (TB). Drug susceptibility testing (DST) for second-line drugs is recommended for these patients, but logistical difficulties have impeded widespread implementation of second-line DST in many settings. To provide a quantitative perspective on the decision to scale up second-line DST, we synthesize literature on the prevalence of second-line drug resistance, the expected clinical and epidemiologic benefits of using second-line DST to ensure that patients with rifampin-resistant TB receive effective regimens, and the costs of implementing (or not implementing) second-line DST for all individuals diagnosed with rifampin-resistant TB. We conclude that, in most settings, second-line DST could substantially improve treatment outcomes for patients with rifampin-resistant TB, reduce transmission of drug-resistant TB, prevent amplification of drug resistance, and be affordable or even cost-saving. Given the large investment made in each patient treated for rifampin-resistant TB, these payoffs would come at relatively small incremental cost. These anticipated benefits likely justify addressing the real challenges faced in implementing second-line DST in most high-burden settings.

Multidrug-resistant tuberculosis treatment failure detection depends on monitoring interval and microbiological method.

Debate persists about monitoring method (culture or smear) and interval (monthly or less frequently) during treatment for multidrug-resistant tuberculosis (MDR-TB). We analysed existing data and estimated the effect of monitoring strategies on timing of failure detection.We identified studies reporting microbiological response to MDR-TB treatment and solicited individual patient data from authors. Frailty survival models were used to estimate pooled relative risk of failure detection in the last 12 months of treatment; hazard of failure using monthly culture was the reference.Data were obtained for 5410 patients across 12 observational studies. During the last 12 months of treatment, failure detection occurred in a median of 3 months by monthly culture; failure detection was delayed by 2, 7, and 9 months relying on bimonthly culture, monthly smear and bimonthly smear, respectively. Risk (95% CI) of failure detection delay resulting from monthly smear relative to culture is 0.38 (0.34-0.42) for all patients and 0.33 (0.25-0.42) for HIV-co-infected patients.Failure detection is delayed by reducing the sensitivity and frequency of the monitoring method. Monthly monitoring of sputum cultures from patients receiving MDR-TB treatment is recommended. Expanded laboratory capacity is needed for high-quality culture, and for smear microscopy and rapid molecular tests.

World Health Organization group 5 drugs for the treatment of drug-resistant tuberculosis: unclear efficacy or untapped potential?

BACKGROUND: Treatment of multidrug-resistant or extensively drug-resistant tuberculosis (DR-tuberculosis) is challenging because commonly used second-line drugs are poorly efficacious and highly toxic. Although World Health Organization group 5 drugs are not recommended for routine use because of unclear activity, some may have untapped potential as more efficacious or better tolerated alternatives. METHODS: We conducted an exhaustive review of in vitro, animal, and clinical studies of group 5 drugs to identify critical research questions that may inform their use in current treatment of DR-tuberculosis and clinical trials of new DR-tuberculosis regimens. RESULTS: Clofazimine may contribute to new short-course DR-tuberculosis regimens. Beta-lactams merit further evaluation-specifically optimization of dose and schedule. Linezolid appears to be effective but is frequently discontinued due to toxicity. Thiacetazone is too toxic to warrant further evaluation. Mycobacterium tuberculosis has intrinsic inducible resistance to clarithromycin. CONCLUSIONS: Clofazimine and beta-lactams may have unrealized potential in the treatment of DR-tuberculosis and warrant further study. Serious toxicities or intrinsic resistance limit the utility of other group 5 drugs. For several group 5 compounds, better understanding of structure-toxicity relationships may lead to better-tolerated analogs.

Old drugs, new purpose: retooling existing drugs for optimized treatment of resistant tuberculosis.

Treatment of drug-resistant tuberculosis is hindered by the high toxicity and poor efficacy of second-line drugs. New compounds must be used together with existing drugs, yet clinical trials to optimize combinations of drugs for drug-resistant tuberculosis are lacking. We conducted an extensive review of existing in vitro, animal, and clinical studies involving World Health Organization-defined group 1, 2, and 4 drugs used in drug-resistant tuberculosis regimens to inform clinical trials and identify critical research questions. Results suggest that optimizing the dosing of pyrazinamide, the injectables, and isoniazid for drug-resistant tuberculosis is a high priority. Additional pharmacokinetic, pharmacodynamic, and toxicodynamic studies are needed for pyrazinamide and ethionamide. Clinical trials of the comparative efficacy and appropriate treatment duration of injectables are recommended. For isoniazid, rapid genotypic tests for Mycobacterium tuberculosis mutations should be nested in clinical trials. Further research focusing on optimization of dose and duration of drugs with activity against drug-resistant tuberculosis is paramount.

Community-based therapy for multidrug-resistant tuberculosis in Lima, Peru.

BACKGROUND: Despite the prevalence of multidrug-resistant tuberculosis in nearly all low-income countries surveyed, effective therapy has been deemed too expensive and considered not to be feasible outside referral centers. We evaluated the results of community-based therapy for multidrug-resistant tuberculosis in a poor section of Lima, Peru. METHODS: We describe the first 75 patients to receive ambulatory treatment with individualized regimens for chronic multidrug-resistant tuberculosis in northern Lima. We conducted a retrospective review of the charts of all patients enrolled in the program between August 1, 1996, and February 1, 1999, and identified predictors of poor outcomes. RESULTS: The infecting strains of Mycobacterium tuberculosis were resistant to a median of six drugs. Among the 66 patients who completed four or more months of therapy, 83 percent (55) were probably cured at the completion of treatment. Five of these 66 patients (8 percent) died while receiving therapy. Only one patient continued to have positive cultures after six months of treatment. All patients in whom treatment failed or who died had extensive bilateral pulmonary disease. In a multiple Cox proportional-hazards regression model, the predictors of the time to treatment failure or death were a low hematocrit (hazard ratio, 4.09; 95 percent confidence interval, 1.35 to 12.36) and a low body-mass index (hazard ratio, 3.23; 95 percent confidence interval, 0.90 to 11.53). Inclusion of pyrazinamide and ethambutol in the regimen (when susceptibility was confirmed) was associated with a favorable outcome (hazard ratio for treatment failure or death, 0.30; 95 percent confidence interval, 0.11 to 0.83). CONCLUSIONS: Community-based outpatient treatment of multidrug-resistant tuberculosis can yield high cure rates even in resource-poor settings. Early initiation of appropriate therapy can preserve susceptibility to first-line drugs and improve treatment outcomes.

Informatics tools to monitor progress and outcomes of patients with drug resistant tuberculosis in Peru.

Multi-drug resistant tuberculosis (MDR-TB) is an important and growing problem in many developing countries. New strategies have been developed to combat the disease but require complex treatment regimens and close monitoring of patients' bacteriology results. We describe a web-based medical record system deployed in Peru to support the management of MDR-TB. Web-based analyses have been developed to track drug sensitivity test results, patterns of sputum smear and culture results and time to conversion from positive to negative cultures. Individual and aggregate drug requirements can also be monitored in real time. Multiple analyses can be linked together and data can be graphed or downloaded to spreadsheets. Over 1200 patients are currently in the system. We argue that such a web-based clinical and epidemiological management system is an important component for successful implementation of complex health interventions in resource poor areas.