Delamanid in the treatment of multidrug-resistant tuberculosis.

Otsuka has been engaged in anti-tuberculosis drug development efforts for over 30 years, and is the leading private sector funder of tuberculosis (TB) research and development. Delamanid (DLM), discovered by Otsuka's scientists, has been shown to provide benefit with respect to short-term surrogate markers and long-term treatment outcomes, and it has received regulatory approval for treatment of adult pulmonary multidrug-resistant TB (MDR-TB) as one of only two new anti-tuberculosis drugs in the last 40 years. Lack of drug-drug interactions with major antiretrovirals and efficacy against MDR-TB allow DLM's applicability in a wide range of MDR-TB patients. Current and future efforts are focused on replacing less safe and less efficacious second-line drugs with DLM, its contribution to all-oral and/or shortened treatment regimens, and, ultimately, inclusion in a pan-TB regimen. This manuscript provides a brief review of DLM.

Early bactericidal activity of delamanid (OPC-67683) in smear-positive pulmonary tuberculosis patients.

BACKGROUND: Delamanid (OPC-67683) is a novel mycolic acid biosynthesis inhibitor active against Mycobacterium tuberculosis at a low minimum inhibitory concentration. METHODS: Forty-eight patients with smear-positive tuberculosis (63% male; 54.7 ± 9.9 kg; 30.7 ± 10.8 years) were randomly assigned to receive delamanid 100, 200, 300 or 400 mg daily for 14 days. Colony forming units (cfu) of M. tuberculosis were counted on agar plates from overnight sputum collections to calculate early bactericidal activity (EBA), defined as fall in log(10) cfu/ml sputum/day. RESULTS: The EBA of delamanid was monophasic and not significantly different between dosages; however, more patients receiving 200 mg (70%) and 300 mg (80%) experienced a response of ≥0.9 log(10) cfu/ml sputum decline over 14 days than those receiving 100 mg (45%) and 400 mg (27%). The average EBA of all dosages combined (0.040 ± 0.056 log(10) cfu/ml sputum/day) was significant from day 2 onward. Delamanid exposure was less than dosage-proportional, reaching a plateau at 300 mg, likely due to dose-limited absorption. Moderate but significant correlation was found between C(max) and EBA, indicating exposure dependence. Delamanid was well tolerated without significant toxicity. CONCLUSIONS: Delamanid at all dosages was safe, well tolerated and demonstrated significant exposure-dependent EBA over 14 days, supporting further investigation of its pharmacokinetics and anti-tuberculosis activity.

Acceptability of short-course rifampin and pyrazinamide treatment of latent tuberculosis infection among jail inmates.

STUDY OBJECTIVES: To determine whether short-course treatment of latent tuberculosis infection (LTBI) with 2 months of rifampin and pyrazinamide (2RZ) is well tolerated and leads to increased treatment completion among jail inmates, a group who may benefit from targeted testing and treatment for LTBI but for whom completion of > or = 6 months of isoniazid treatment is difficult because of the short duration of incarceration. DESIGN: Prospective cohort. SETTING: Large, urban county jail. PATIENTS: All inmates admitted to the Fulton County Jail who had positive tuberculin skin test results, normal findings on chest radiography, and expected duration of incarceration of at least 60 days. INTERVENTION: Inmates were offered 2RZ via daily directly observed therapy for 60 doses as an alternative to isoniazid therapy. MEASUREMENTS AND RESULTS: We measured the completion of 2RZ treatment and toxicity due to 2RZ treatment during incarceration. From December 14, 1998, through December 13, 1999, 1,360 new inmates had positive tuberculin skin test results and normal findings on chest radiography, and 168 new inmates had an expected duration of incarceration of > or = 60 days. One hundred sixty-six inmates (> 99%) were HIV-negative. Eighty-one inmates (48%) completed 60 doses of 2RZ treatment while incarcerated. Seventy-four inmates (44%) were released before completion. Treatment was stopped in 1 inmate (< 1%) for asymptomatic elevation of asparginine aminotransferase (> or = 10 times normal) and in 12 inmates (7%) for minor complaints. Twenty-one inmates had completed isoniazid treatment in the year before the availability of 2RZ, and 9 inmates completed isoniazid treatment in the year during the availability of 2RZ. CONCLUSIONS: 2RZ was acceptable to and well tolerated by inmates, and led to a marked increase in the number of inmates completing treatment of LTBI during incarceration.

Antituberculosis activity of once-weekly rifapentine-containing regimens in mice. Long-term effectiveness with 6- and 8-month treatment regimens.

The effectiveness of various once-weekly 10 mg/kg rifapentine (P)- containing regimens for treatment of tuberculosis was assessed in mice infected intravenously with 4.3 x 10(6) colony-forming units (cfu) of Mycobacterium tuberculosis H37Rv, and treated 14 d later with various combinations of rifampin (R), P, isoniazid (H), pyrazinamide (Z), ethambutol (E), or streptomycin (S). Control mice treated daily with either 2-mo HRZ + 4-mo HR or 2-mo HRZ + 6-mo HE were rendered spleen and lung culture-negative at 6 mo and 8 mo, respectively. Treatment failure with emergence of R-resistant bacilli occurred in all mice given once-weekly monotherapy with P for 6 mo. Once-weekly PH treatment was successful at 6 mo when it was preceded by a 2-mo daily phase with HRZ. When the initial daily phase was reduced to 2 wk, once-weekly PH-containing treatment was successful, at 6 mo, only if it was supplemented with S during the initial daily and the once-weekly phases, and at 8 mo if it was supplemented with daily H during the once-weekly phase. Without these supplements, once-weekly treatment failed in some mice with selection of R-resistant or H-resistant mutants.

A model of the cost-effectiveness of directly observed therapy for treatment of tuberculosis.

A hypothetical cohort of 25,000 TB patients and their contacts were followed for a 10-year period; rates of treatment default, infectiousness following partial treatment, relapse, hospitalization, and development of drug-resistant TB were included. The average cost per case cured was $16,846 with 15% of patients starting DOT, $17,323 with 100% starting DOT, and $20,106 with none starting DOT. The incremental cost per additional case cured was $24,064 when all patients, started treatment on DOT, indicating that outpatient DOT provides a cost-effective method of improving health outcomes for TB patients and their contacts while controlling direct costs.

Rifampin preventive therapy for tuberculosis infection: experience with 157 adolescents.

For persons infected with Mycobacterium tuberculosis resistant to isoniazid (INH), rifampin is recommended for the prevention of active disease. However, the adverse effects and acceptability of this preventive therapy are largely uncharacterized. We prospectively followed 157 high-school students exposed to, and probably infected with, M. tuberculosis strains resistant to INH. All 157 students were prescribed preventive therapy with rifampin (10 mg/kg up to 600 mg daily) for 24 wk. While receiving therapy, 41 (26%) reported one or more adverse effects; of these, 18 had therapy interrupted temporarily, two permanently. Four (2.5%) had alanine aminotransferase elevations greater than two times the upper limit of normal (range, 91 to 161 U/L); of these, one had therapy permanently stopped. Six (3.8%) self-discontinued therapy. No student was found to have active disease during the 2 yr of the study (exact 95% upper confidence limit, 2.2). We assumed that without preventive therapy, seven cases of tuberculosis would have occurred during these 2 yr. Therefore, we estimated that rifampin had a minimum protective effect of 56%. In conclusion, preventive therapy with rifampin was well tolerated and well accepted, and it appears effective in preventing active tuberculosis.

Can physicians treat tuberculosis? Report on a national survey of physician practices.

OBJECTIVES: Researchers examined physicians' treatment strategies for tuberculosis to determine whether they would follow recommendations of the Centers for Disease Control and Prevention and the American Thoracic Society. METHODS: A national survey sampled 1772 physicians. Analyses tested correlates of recommended treatment regimens. RESULTS: Among respondents, 59.4% described a recommended regimen. Specialists; physicians aware of professional publications, treatment recommendations, and reporting requirements; and those having more than 50% of patients in nursing homes were more likely to describe recommended regimens. Physicians who had been in practice longer, relied on personal experience, or had more than 50% of patients receiving Medicaid were less likely to describe recommended regimens. CONCLUSIONS: Physicians who treat tuberculosis require training and support. Policymakers should consider who should treat tuberculosis and how recommended practice should be ensured.

[Compliance and tolerance of new antitubercular short-term chemopreventive regimens in childhood--a pilot project]. / Compliance und Toleranz neuer antituberkulotischer Kurzzeit-Chemopräventionsregime im Kindesalter--eine Pilotstudie.

Efficacy of preventive chemotherapy in tuberculosis-infected children depends to a great extend on medical compliance and drug tolerability. Two new short-course chemoprevention-regimes of tuberculosis--four months Rifampin (A) and two months Rifampin plus Pyrazinamide (B)--were compared with the well established regimen of six months Isoniacid (C). 150 children (mean age 3.6 years with Tb conversion) were randomly allocated to these three regimens. 13 patients were non-compliant, in terms of interview, urinary INH-test strips, urine colour and prescription frequency: 7 in group C and 3 in group A and B, respectively. Adverse effects were observed in 5 patients: 3 in group C and 1 in group A and B. 1 child (group B) developed tuberculosis two years after stopping short course chemoprevention. Good compliance (94%) as well as neglectable risks of adverse effects (2%) justify further controlled studies to evaluate the efficacy of short course chemoprevention in childhood.

Purified protein derivative tuberculin and delayed-type hypersensitivity skin testing in migrant farm workers at risk for tuberculosis and HIV coinfection.

OBJECTIVE: To assess the joint use of purified protein derivative (PPD) and delayed-type hypersensitivity (DTH) antigens in screening individuals of unknown HIV serostatus for tuberculosis (TB) preventive therapy eligibility. DESIGN: Population-based survey. METHODS: A group of migrant farm workers were screened for HIV and skin-tested with PPD, tetanus toxoid (TET), Candida albicans (CAN) and mumps (MUM) antigens by the Mantoux method. Anergy was defined as a < or = 2 mm reaction to all four antigens. Eligibility for preventive therapy was defined as a reaction of > or = 5 mm to PPD among HIV-seropositive individuals, > or = 10 mm among HIV-seronegatives, or anergy. RESULTS: A total of 253 out of 271 individuals had sufficient data for analysis. Of these, 15 (5%) were HIV-seropositive; 183 (75%), 175 (72%) and 157 (65%) reacted to TET, CAN, and MUM, respectively, and 113 (47%) were eligible for preventive therapy [108 (44%) PPD-positive, five (2%) anergic]. Use of PPD alone was 95% sensitive for detecting preventive therapy eligibility; PPD plus one DTH antigen was more sensitive (99%) but less specific (range, 69-85%); PPD plus two DTH antigens was most specific (CAN + MUM, 84%; TET + MUM, 93%; and TET + CAN, 100%). CONCLUSIONS: In this population with 5% HIV seroprevalence, testing for anergy did not significantly increase the detection of preventive therapy eligibility. The use of two DTH antigens is very sensitive and specific. These results support the recommendation of joint PPD and anergy testing for the screening of HIV-seropositive individuals. Our data also suggest, however, that for individuals whose HIV serostatus is unknown, anergy testing should be considered as a screening tool only if the prevalence of anergy is expected to exceed the prevalence of PPD positivity.

Nosocomial outbreak of tuberculosis in a renal transplant unit: application of a new technique for restriction fragment length polymorphism analysis of Mycobacterium tuberculosis isolates.

From January 1990 through February 1991, tuberculosis (TB) developed in 10 renal transplant (RT) patients at one hospital; 5 patients died. Possible nosocomial transmission was investigated. Mycobacterium tuberculosis isolates were compared by restriction fragment length polymorphism (RFLP) by a polymerase chain reaction method. The source case occurred in an RT patient (source) who had posttransplant exposure to TB at another hospital. The source patient was rehospitalized on the RT unit; diagnosis of TB and thus isolation precautions were delayed. Epidemiologic and RFLP analysis showed transmission from the source to 5 RT patients and 1 human immunodeficiency virus-infected patient. M. tuberculosis isolates from 4 RT patients had other RFLP patterns. The median incubation period for TB in RT patients was 7.5 weeks (range, 5-11). Bronchoscopy and intubation of the source patient and inadequate ventilation on the RT unit possibly increased transmission. Early detection of TB and effective isolation are essential to prevent nosocomial transmission.

The multidrug-resistant tuberculosis challenge to public health efforts to control tuberculosis.

After years of steady decline, there has been an unprecedented resurgence of tuberculosis (TB) in the United States and outbreaks of multidrug-resistant tuberculosis (MDR-TB). The authors assess the nature, epidemiology, and implications of MDR-TB; provide suggestions for preventing drug resistance among patients with drug-susceptible TB; and offer recommendations for managing patients with MDR-TB. They outline the National Action Plan to Combat MDR-TB. Close collaboration among medical practitioners and staff members of TB control programs is needed to ensure the most effective management of patients with TB and their contacts. This collaboration is one of the most important steps for successful control of MDR-TB.

Usefulness of skin testing with mycobacterial antigens in children with cervical lymphadenopathy.

One hundred twenty-three children with chronic cervical lymphadenopathy were skin-tested with purified protein derivative (PPD)-B (Mycobacterium intracellulare), PPD-Y (Mycobacterium kansasii), PPD-G (Mycobacterium scrofulaceum) (nontuberculous mycobacterial antigens (NTMags)) and PPD-T (Mycobacterium tuberculosis). Children with culture-confirmed mycobacterial disease had significantly larger reactions to NTMags and were 6 times more likely to have PPD-B responses of greater than or equal to 10 mm than those with negative microscopy/culture results. Children with acid-fast bacilli present in clinical specimens but with negative culture results were 3 times more likely to have greater than or equal to 10 mm induration to PPD-B than those with negative microscopy/culture results. In all groups except those with culture-confirmed M. tuberculosis, responses to PPD-T were significantly smaller than those to the NTMags. We conclude that NTMags, particularly PPD-B, may be useful in diagnosing childhood mycobacterial cervical adenopathy; however, their usefulness in distinguishing disease caused by M. tuberculosis from that resulting from other mycobacteria is unknown.

Evaluation of the clinical usefulness of mycobacterial skin test antigens in adults with pulmonary mycobacterioses.

A double-blind, multicenter study was conducted to evaluate the usefulness of mycobacterial skin test antigens for the specific diagnosis of adult pulmonary mycobacterial disease. The skin test antigens used were PPD-T (M. bovis) and PPD-B (M. intracellulare), made bioequivalent to 5 TU PPD-S through bioassay in human subjects. Of the 192 adults (18 yr of age or older), those with disease caused by M. tuberculosis (MTB) had significantly larger reactions to PPD-T than did those with disease caused by nontuberculous mycobacteria (NTM) or those with negative culture results (NEG)(13.41 mm versus 4.87 and 4.96 mm, respectively, p less than 0.001). The mean induration to PPD-B in NTM was not different from that in MTB or NEG. Defining a "positive" to be greater than or equal to 10 mm induration and a size difference of greater than or equal to 3 mm between PPD-T and PPD-B, the sensitivity, specificity, and positive predictive value (PPV) for PPD-T in diagnosing MTB versus NTM was 29, 90, and 75%. Corresponding values for PPD-B and NTM disease were 70, 61, and 64%. Dual testing was less useful in distinguishing disease caused by any of the mycobacteria from NEG. Although the sensitivity of PPD-B, made bioequivalent to PPD-S, was high, the specificity and PPV were low. We conclude that this preparation of PPD-B is no more useful in distinguishing adult pulmonary disease caused by NTM than is PPD-T alone.

Rifabutin (ansamycin LM427) for the treatment of pulmonary Mycobacterium avium complex.

During the period October 1983 through January 1988, the Centers for Disease Control (CDC) provided the experimental drug rifabutin (ansamycin LM427) to 406 patients with severe, progressive Mycobacterium avium complex pulmonary disease who had been unresponsive to standard therapy. Selected patients were randomly assigned to doses of 150, 300, or 450 mg rifabutin. Choice of companion drugs was left to the treating physicians. In the analysis of data from this program, we examined the relationship between response to treatment, as measured by bacteriologic sputum conversion, survival, weight gain, improvement in respiratory symptoms, and subjective assessment of clinical improvement, and a variety of patient and treatment variables. Although in some of the analyses a higher rifabutin dose appeared to be associated with sputum conversion, survival, and clinical improvement, the drug did not have a marked effect on outcome. The role of rifabutin in the treatment of this disease will best be assessed in a controlled clinical trial.

USPHS Tuberculosis Short-Course Chemotherapy Trial 21: effectiveness, toxicity, and acceptability. The report of final results.

STUDY OBJECTIVE: To determine the effectiveness, toxicity, and acceptability of a 6-month antituberculous regimen compared with a 9-month regimen. DESIGN: A nonblinded, unbalanced, randomized, multicenter clinical trial. SETTING: Twenty-two tuberculosis clinics in public health departments and hospitals in the United States. PATIENTS: Patients were eligible if Mycobacterium tuberculosis, isolated from sputum cultures, was susceptible to study drugs. Of 1451 patients enrolled, 75% (617 of 823) assigned to the 6-month regimen and 71% (445 of 628) assigned to the 9-month regimen were eligible. INTERVENTIONS: Patients took self-administered isoniazid and rifampin daily for 24 weeks (6-month regimen) or 36 weeks (9-month regimen). In addition, patients assigned to the 6-month regimen took self-administered pyrazinamide daily during the first 8 weeks. RESULTS: Patients on the 6-month regimen converted more rapidly than patients on the 9-month regimen (94.6% compared with 89.9% after 16 weeks of therapy, with a difference of 4.7% [95% CI, 0.7% to 8.7%]); had similar rates of adverse drug reactions (7.7% compared with 6.4%, with a difference of 1.3% [95% CI, 0.0% to 4.6%]); had lower noncompliance rates (16.8% compared with 29.2%, with a difference of 12.4% [95% CI, 6.8% to 18.0%]); and had similar relapse rates 96 weeks after completing therapy (3.5% compared with 2.8%, with a difference of 0.7% [95% CI, 0.0% to 3.9%]). A significantly greater proportion of patients assigned to the 6-month regimen successfully completed therapy (61.4% compared with 50.6%; chi 2 = 11.976). CONCLUSIONS: Our results suggest that this 6-month regimen is similar in effectiveness, toxicity, and acceptability to the 9-month regimen for treating pulmonary tuberculosis.