Implementation of Bedaquiline, Pretomanid, and Linezolid in the United States: Experience Using a Novel All-Oral Treatment Regimen for Treatment of Rifampin-Resistant or Rifampin-Intolerant Tuberculosis Disease

BACKGROUND

Rifampin-resistant tuberculosis is a leading cause of morbidity worldwide; only one-third of persons start treatment, and outcomes are often inadequate. Several trials demonstrate 90% efficacy using an all-oral, 6-month regimen of bedaquiline, pretomanid, and linezolid (BPaL), but significant toxicity occurred using 1200-mg linezolid. After US Food and Drug Administration approval in 2019, some US clinicians rapidly implemented BPaL using an initial 600-mg linezolid dose adjusted by serum drug concentrations and clinical monitoring.

METHODS

Data from US patients treated with BPaL between 14 October 2019 and 30 April 2022 were compiled and analyzed by the BPaL Implementation Group (BIG), including baseline examination and laboratory, electrocardiographic, and clinical monitoring throughout treatment and follow-up. Linezolid dosing and clinical management was provider driven, and most patients had linezolid adjusted by therapeutic drug monitoring.

RESULTS

Of 70 patients starting BPaL, 2 changed to rifampin-based therapy, 68 (97.1%) completed BPaL, and 2 of the 68 (2.9%) experienced relapse after completion. Using an initial 600-mg linezolid dose daily adjusted by therapeutic drug monitoring and careful clinical and laboratory monitoring for adverse effects, supportive care, and expert consultation throughout BPaL treatment, 3 patients (4.4%) with hematologic toxicity and 4 (5.9%) with neurotoxicity required a change in linezolid dose or frequency. The median BPaL duration was 6 months.

CONCLUSIONS

BPaL has transformed treatment for rifampin-resistant or intolerant tuberculosis. In this cohort, effective treatment required less than half the duration recommended in 2019 US guidelines for drug-resistant tuberculosis. Use of individualized linezolid dosing and monitoring likely enhanced safety and treatment completion. The BIG cohort demonstrates that early implementation of new tuberculosis treatments in the United States is feasible.

Concomitant Treatment of Tuberculosis and Hepatitis C Virus in Coinfected Patients Using Serum Drug Concentration Monitoring

Background

Concern for drug-drug interactions leading to treatment failure and drug-resistant strains have discouraged clinicians from attempting concomitant treatment of hepatitis C virus (HCV) and tuberculosis (TB). Increased metabolism of direct-acting antivirals (DAAs) by rifamycins has hindered concurrent use. Development of an assay for ledipasvir and sofosbuvir (LDV/SOF) serum concentrations for therapeutic drug monitoring (TDM) can ensure adequate therapy. We present the first cases of concomitant therapy of active TB and HCV with rifamycin-containing regimens and DAAs using TDM.

Methods

Using TDM, we aim to determine whether concomitant therapy with rifamycin-containing regimens and DAAs is safe and effective for patients coinfected with TB and HCV. Five individuals with TB and HCV who experienced transaminitis before or during TB therapy were concomitantly treated with rifamycin-containing regimens and LDV/SOF. Therapeutic drug monitoring was performed for LDV, SOF, and rifabutin during therapy. Baseline laboratory tests and serial liver enzymes were performed. Hepatitis C virus viral load and mycobacterial sputum cultures were obtained upon completion of therapy to determine efficacy of therapy.

Results

All patients were found to have nondetectable HCV viral loads and negative mycobacterial sputum cultures upon completion of therapy. No clinically significant adverse effects were reported.

Conclusions

These cases illustrate concomitant use of LDV/SOF and rifabutin in patients with HCV/TB coinfection. Utilizing serum drug concentration monitoring to guide dosing, correction of transaminitis were achieved, which allowed the use rifamycin-containing TB therapy. These findings suggest that concomitant therapy of TB/HCV is possible, safe, and effective.

Therapeutic drug monitoring and TB treatment outcomes in patients with diabetes mellitus

BACKGROUND: Diabetes mellitus (DM) increases the risk of TB disease and poor treatment outcomes such as delayed sputum culture conversion due to inadequate drug exposure. Therapeutic drug monitoring (TDM) has improved these outcomes in some settings.METHODS: To compare treatment outcomes in programs with routine TDM vs. programs that did not use TDM, we conducted a retrospective study among people with DM and TB at health departments in four US states.RESULTS: A total of 170 patients were enrolled (73 patients in the non-TDM group and 97 patients in the TDM group). Days to sputum culture conversion and total treatment duration were significantly shorter in the TDM group vs. the non-TDM group. In adjusted analyses, patients who underwent TDM were significantly more likely to achieve sputum culture conversion at 2 months (P = 0.007).CONCLUSION: TDM hastened microbiological cure from TB among people with DM and a high risk for poor treatment outcomes in the programmatic setting.

2354. Implementation of BPaL in the United States: Experience using a novel all-oral treatment regimen for rifampin-resistant or treatment-intolerant TB disease

Background

Tuberculosis (TB) remains a leading infectious cause of death and morbidity globally. Rifampin-resistance or intolerance requires prolonged treatment using less effective, more toxic regimens. Recent trials demonstrated that the all-oral six-month “BPaL” regimen, Bedaquiline, Pretomanid and Linezolid, is 90% effective. In these trials, linezolid-induced hematologic and neurologic toxicity was high using 1200mg daily, whereas lower exposure (dose or duration) reduced toxicity. Therapeutic drug monitoring (TDM) is used by U.S. TB experts to maintain a serum linezolid trough < 2ug/ml, which correlates with reduced toxicity. Since U.S. FDA approval in 2019, BPaL has been widely implemented for the treatment of rifampin-intolerant or resistant TB disease.

Methods

We evaluated a cohort of patients with TB treated from October, 2019 through April, 2022, describing patient demographics, BPaL treatment dosing, and adverse events. TDM was performed for clinical purposes using liquid chromatography–mass spectrometry to measure serum levels at trough and 2 and 6h post-linezolid dose. Clinical providers adjusted linezolid dose and dosing interval targeting a trough < 2ug/ml and peak of 12–26ug/ml.

Results

Among 64 BPaL patients, ages were 15–83 years, 22 (34.3%) were female, 6 (9.3%) U.S.-born, 4 (6.3%) HIV-infected. 50 (78.1%) had only pulmonary disease, 6 extrapulmonary, and 8 had both; 61 (91.0%) were culture-confirmed. Most (n=62) started linezolid 600mg daily. Linezolid was adjusted for 39 (66.1%) of the 59 patients with TDM; 18 had a trough >2ug/ml, 30 had dosing interval increased to thrice-weekly, and 17 had a dose increase. 52 (81.3%) patients completed BPaL and 12 remain on therapy. One 81-year-old female with diabetes, hypothyroidism, and B12 deficiency discontinued linezolid at 12 weeks for worsened neuropathy (linezolid trough=1.13ug/ml). She completed 26 weeks of bedaquiline/pretomanid and her symptoms returned to baseline.

Conclusion

Use of BPaL with clinical and TDM monitoring has transformed treatment of rifampin-resistant or intolerant TB in the U.S. Patients previously sentenced to 18–24 months of treatment with 5–7 hard-to-tolerate medications and modest efficacy can now complete treatment in 6–9 months with little toxicity and exceptional cure rates.

Disclosures

All Authors: No reported disclosures.

Effect of Rifabutin in Dolutegravir Dosing: A Case Series

Background: Tuberculosis (TB) is the leading cause of death in human immunodeficiency virus (HIV)-infected people worldwide. Currently there are no studies examining the use of Rifabutin (RBN) and Dolutegravir (DTG) in co-infected persons. This is a case series of 4 co-infected patients receiving both agents who underwent Pharmacokinetic (PK) analysis. Methods and Results: This is a retrospective chart review study of four patients diagnosed with both HIV and TB, receiving RBN and DTG and undergoing therapeutic drug monitoring. All 4 cases had lower than expected DTG concentrations at least once, including those on the current recommended dose of DTG with RBN, and even those receiving higher doses. Conclusions: Given the frequency of low DTG and RBN concentrations, therapeutic drug monitoring (TDM) for these drugs is advisable. Prospective clinical studies are needed to further determine the PK interactions between RBN and DTG, and virologic response to treatment.

1400. Pretomanid in the Treatment of Patients with Tuberculosis in the United States: the Bedaquiline, Pretomanid and Linezolid (BPaL) Accelerated Monitoring (BAM) Project

Background

In August 2019 the U.S. FDA approved pretomanid as part of a 6-month all-oral BPaL (bedaquiline, pretomanid, and linezolid) regimen for treating pulmonary extensively drug-resistant (XDR) or treatment-intolerant or nonresponsive multidrug-resistant (MDR) tuberculosis (TB). In the study supporting approval, 89% of patients had a favorable outcome, and all reported ≥ 1 adverse event. We describe the reported use of BPaL in the United States.

Methods

Using the 2020 CDC Report of a Verified Case of Tuberculosis (RVCT) MDR TB supplemental form, TB programs and providers submitted data for patients who began taking BPaL between Aug 1, 2019 and May 1, 2020, for retrospective descriptive analysis.

Results

Programs and providers reported 17 TB patients aged a mean of 41 years (range 23–76) who received BPaL: 11 (65%) were male; 15 (88%) were non-U.S. born; 15 (88%) had pulmonary TB disease only; two (12%) had both pulmonary and extrapulmonary disease. Of all patients, 16 had Mycobacterium tuberculosis isolated from sputum and 7 (44%) had cavitary disease. The preliminary drug susceptibilities were 8 MDR patterns, 8 pre-XDR, and 1 unreported. Three patients received BPaL as their only treatment; six first received treatment for drug-susceptible TB, and eight received other regimens for MDR TB before BPaL. Eleven (65%) patients had ≥ 1 side effect reported during any TB treatment, including peripheral neuropathy (n=5), depression (n=4), vestibular dysfunction (n=3), and vision changes (n=3). Timing related to specific TB drug use was not reported. Sixteen (94%) patients received less than the approved initial dose of 1200 mg linezolid daily, and 15 (88%) patients underwent monitoring of linezolid exposure. All 16 patients with M. tuberculosis in initial sputa converted to negative culture results within 6 months of starting treatment. At 12 months after BPaL initiation, all patients had completed treatment, without TB recurrences or deaths reported.

Conclusion

In the early period after FDA approval, most U.S. patients received BPaL off-label with an initial linezolid dose lower than the approved 1200mg yet still achieved good outcomes. Most reported patients underwent some monitoring of linezolid exposure. Monitoring of BPaL use is important and should continue.

Disclosures

All Authors: No reported disclosures

Novel 6-Month Treatment for Drug-Resistant Tuberculosis, United States

The US Food and Drug Administration approved a 6-month regimen of pretomanid, bedaquiline, and linezolid for extensively drug-resistant or multidrug-intolerant tuberculosis after a trial in South Africa demonstrated 90% effectiveness 6 months posttreatment. We report on a patient who completed the regimen using a lower linezolid dose.

Tuberculosis following PD-1 blockade for cancer immunotherapy

Because of the well-established therapeutic benefit of boosting antitumor responses through blockade of the T cell inhibitory receptor PD-1, it has been proposed that PD-1 blockade could also be useful in infectious disease settings, including Mycobacterium tuberculosis (Mtb) infection. However, in preclinical models, Mtb-infected PD-1^-/- mice mount exaggerated T_H1 responses that drive lethal immunopathology. Multiple cases of tuberculosis during PD-1 blockade have been observed in patients with cancer, but in humans little is understood about Mtb-specific immune responses during checkpoint blockade-associated tuberculosis. Here, we report two more cases. We describe a patient who succumbed to disseminated tuberculosis after PD-1 blockade for treatment of nasopharyngeal carcinoma, and we examine Mtb-specific immune responses in a patient with Merkel cell carcinoma who developed checkpoint blockade-associated tuberculosis and was successfully treated for the infection. After anti-PD-1 administration, interferon-γ-producing Mtb-specific CD4 T cells became more prevalent in the blood, and a tuberculoma developed a few months thereafter. Mtb-specific T_H17 cells, CD8 T cells, regulatory T cells, and antibody abundance did not change before the appearance of the granuloma. These results are consistent with the murine model data and suggest that boosting T_H1 function with PD-1 blockade may increase the risk or severity of tuberculosis in humans.

Tuberculosis Regional Training and Medical Consultation Centers in the United States: Characteristics, outcomes, and quality of medical consultations, June 1, 2010 - May 31, 2014

BACKGROUND

Tuberculosis (TB) Regional Training and Medical Consultation Centers (RTMCCs) were established in 2005 for TB medical consultation, training and education in the United States. A medical consultation database (MCD) captured all consultations provided by RTMCCs; we report on those provided from June 1, 2010 to May 31, 2014.

METHODS

All MCD consultations during 2010-2014 were categorized into: provider type, setting, consultation topic, and patient age. We analyzed data frequencies and performed subgroup analyses by RTMCC, by TB incidence for the geographical area, and by year of consultation. End-user satisfaction was assessed by a 2016 telephone evaluation of RTMCC services.

RESULTS

A total of 11,074 consultations were delivered, with 10,754 (97.1%) in the U.S. and its current or former territories. Of these, 6018 (56%) were for high, 2443 (22.7%) for medium, and 2293 (21.3%) for low TB incidence settings. Most were for adults (81.3%) and answered within 24 h (96.2%). Nearly 2/3 consultations originated from health departments; providers included mostly physicians (44.3%) or nurses (37.6%). Common consult categories included TB disease (47.7%), case management (29.8%), latent TB infection (19.3%), diagnosis (16.1%), pharmacology (14.7%) and adverse side effects (14.3%). Among adverse side effects, hepatotoxicity was most common (39.6%). Volume and nature of consult requests remained relatively stable over the four-year period. Feedback from a 2016 CDC evaluation indicated overall satisfaction with RTMCC medical consultation services.

CONCLUSION

RTMCCS were an important source of TB medical consultation over the time-frame of this assessment and provided quality expert consultation within 24 h. RMTCCs represent a reservoir of TB subject-matter expertise in the United States.

Bacillus Calmette-Guérin Cases Reported to the National Tuberculosis Surveillance System, United States, 2004-2015

Mycobacterium bovis bacillus Calmette-Guérin (BCG) is used as a vaccine to protect against disseminated tuberculosis (TB) and as a treatment for bladder cancer. We describe characteristics of US TB patients reported to the National Tuberculosis Surveillance System (NTSS) whose disease was attributed to BCG. We identified 118 BCG cases and 91,065 TB cases reported to NTSS during 2004-2015. Most patients with BCG were US-born (86%), older (median age 75 years), and non-Hispanic white (81%). Only 17% of BCG cases had pulmonary involvement, in contrast with 84% of TB cases. Epidemiologic features of BCG cases differed from TB cases. Clinicians can use clinical history to discern probable BCG cases from TB cases, enabling optimal clinical management. Public health agencies can use this information to quickly identify probable BCG cases to avoid inappropriately reporting BCG cases to NTSS or expending resources on unnecessary public health interventions.

Evaluation of multiplex polymerase chain reaction utilising multiple targets in Mycobacterium tuberculosis direct test negative but culture positive cases: a potential method for enhancing the diagnosis of tuberculosis

PURPOSE

To evaluate multiplex Polymerase Chain Reaction (MPCR) utilising multiple targets (IS6110, Protein b [Pab] and MPB64 genes) in Mycobacterium tuberculosis Direct Test (MTD) negative but culture positive cases and comparison of MPCR with Real-Time polymerase chain reaction (RT-PCR) for diagnosis of tuberculosis.

MATERIALS AND METHODS

MPCR was carried out on 28 culture positive sputum samples. Out of 28 culture positive samples, 17 were originally reported, as MTD test negative and 11 were MTD test positive, respectively. The results of MPCR were compared with RT-PCR. To check the specificity of the tests, MPCR and RT-PCR were also evaluated with 16 non-tuberculous mycobacterial (NTM) isolates.

RESULTS

Out of 28 culture positive sputum samples, MPCR was positive in all 28/28 samples, whereas RT-PCR was positive in 27/28 samples and MTD test was originally tested positive in six sputum samples and on repeating MTD testing, five more sputum samples were positive and thus total number of MTD positive were 11/28 sputum samples, respectively. All the tests were negative on evaluation with all the 16 NTMs, thus giving specificity of 100% to all the tests; sensitivity of MPCR, RT-PCR and MTD tests were 100%, 96.42% and 39.28%, respectively, in these specifically selected samples.

CONCLUSIONS

MPCR may be an important tool in the rapid diagnosis of tuberculosis especially in disease endemic, resource limited countries.

Outcomes and use of therapeutic drug monitoring in multidrug-resistant tuberculosis patients treated in virginia, 2009-2014

BACKGROUND

Reports of therapeutic drug monitoring (TDM) for second-line medications to treat multidrug-resistant tuberculosis (MDR-TB) remain limited.

METHODS

A retrospective cohort from the Virginia state tuberculosis (TB) registry, 2009-2014, was analyzed for TDM usage in MDR-TB. Drug concentrations, measured at time of estimated peak (Cmax), were compared to expected ranges.

RESULTS

Of 10 patients with MDR-TB, 8 (80%) had TDM for at least one drug (maximum 6 drugs). Second-line drugs tested were cycloserine in seven patients (mean C2hr, 16.6±10.2 µg/mL; 4 [57%] below expected range); moxifloxacin in five (mean C2hr, 3.2±1.5 µg/mL; 1 [20%] below); capreomycin in five (mean C2hr, 21.5±14.0 µg/mL; 3 [60%] below); para-aminosalicylic acid in five (mean C6hr, 65.0±29.1 µg/mL; all within or above); linezolid in three (mean C2hr, 11.4±4.1 µg/mL, 1 [33%] below); amikacin in two (mean C2hr, 35.3±3.7 µg/mL; 1 [50%] below); ethionamide in one (C2hr, 1.49 µg/mL, within expected). Two patients died: a 38-year-old woman with human immunodeficiency virus/acquired immune deficiency syndrome and TB meningitis without TDM, and a 76-year-old man with fluoroquinolone-resistant (pre-extensively drug-resistant) pulmonary TB and low linezolid and capreomycin concentrations.

CONCLUSION

Individual pharmacokinetic variability was common. A more standardized approach to TDM for MDR-TB may limit over-testing and maximize therapeutic gain.

Multidrug resistant pulmonary tuberculosis treatment regimens and patient outcomes: an individual patient data meta-analysis of 9,153 patients

BACKGROUND

Treatment of multidrug resistant tuberculosis (MDR-TB) is lengthy, toxic, expensive, and has generally poor outcomes. We undertook an individual patient data meta-analysis to assess the impact on outcomes of the type, number, and duration of drugs used to treat MDR-TB.

METHODS AND FINDINGS

Three recent systematic reviews were used to identify studies reporting treatment outcomes of microbiologically confirmed MDR-TB. Study authors were contacted to solicit individual patient data including clinical characteristics, treatment given, and outcomes. Random effects multivariable logistic meta-regression was used to estimate adjusted odds of treatment success. Adequate treatment and outcome data were provided for 9,153 patients with MDR-TB from 32 observational studies. Treatment success, compared to failure/relapse, was associated with use of: later generation quinolones, (adjusted odds ratio [aOR]: 2.5 [95% CI 1.1-6.0]), ofloxacin (aOR: 2.5 [1.6-3.9]), ethionamide or prothionamide (aOR: 1.7 [1.3-2.3]), use of four or more likely effective drugs in the initial intensive phase (aOR: 2.3 [1.3-3.9]), and three or more likely effective drugs in the continuation phase (aOR: 2.7 [1.7-4.1]). Similar results were seen for the association of treatment success compared to failure/relapse or death: later generation quinolones, (aOR: 2.7 [1.7-4.3]), ofloxacin (aOR: 2.3 [1.3-3.8]), ethionamide or prothionamide (aOR: 1.7 [1.4-2.1]), use of four or more likely effective drugs in the initial intensive phase (aOR: 2.7 [1.9-3.9]), and three or more likely effective drugs in the continuation phase (aOR: 4.5 [3.4-6.0]).

CONCLUSIONS

In this individual patient data meta-analysis of observational data, improved MDR-TB treatment success and survival were associated with use of certain fluoroquinolones, ethionamide, or prothionamide, and greater total number of effective drugs. However, randomized trials are urgently needed to optimize MDR-TB treatment. Please see later in the article for the Editors' Summary.

Pharmacokinetic evaluation of rifabutin in combination with lopinavir-ritonavir in patients with HIV infection and active tuberculosis

BACKGROUND

Human immunodeficiency virus (HIV)-associated tuberculosis is difficult to treat, given the propensity for drug interactions between the rifamycins and the antiretroviral drugs. We examined the pharmacokinetics of rifabutin before and after the addition of lopinavir-ritonavir.

METHODS

We analyzed 10 patients with HIV infection and active tuberculosis in a state tuberculosis hospital. Plasma was collected for measurement of rifabutin, the microbiologically active 25-desacetyl-rifabutin, and lopinavir by validated high-performance liquid chromatography assays. Samples were collected 2-4 weeks after starting rifabutin at 300 mg thrice weekly without lopinavir-ritonavir, 2 weeks after the addition of lopinavir-ritonavir at 400 and 100 mg, respectively, twice daily to rifabutin at 150 mg thrice weekly, and (if rifabutin plasma concentrations were below the normal range) 2 weeks after an increase in rifabutin to 300 mg thrice weekly with lopinavir-ritonavir. Noncompartmental and population pharmacokinetic analyses (2-compartment open model) were performed.

RESULTS

Rifabutin at 300 mg without lopinavir-ritonavir produced a low maximum plasma concentration (C(max)) in 5 of 10 patients. After the addition of lopinavir-ritonavir to rifabutin at 150 mg, 9 of 10 had low C(max) values. Eight patients had dose increases to 300 mg of rifabutin with lopinavir-ritonavir. Most free rifabutin (unbound to plasma protein) C(max) values were below the tuberculosis minimal inhibitory concentration. For most patients, values for the area under the plasma concentration-time curve were as low or lower than those associated with treatment failure or relapse and with acquired rifamycin resistance in Tuberculosis Trials Consortium/US Public Health Service Study 23. One of the 10 patients experienced relapse with acquired rifamycin resistance.

CONCLUSION

The recommended rifabutin doses for use with lopinavir-ritonavir may be inadequate in many patients. Monitoring of plasma concentrations is recommended.

Acute lung injury outside of the ICU: incidence in respiratory isolation on a general ward

BACKGROUND

Epidemiologic investigations of acute lung injury (ALI) and ARDS have focused on mechanically ventilated patients in ICUs, and have reported high mortality rates. We sought to determine the incidence and lethality of these syndromes in the respiratory isolation areas of general wards, a non-ICU setting that often serves patients with acute lung processes.

METHODS

We prospectively studied all patients who were admitted to respiratory isolation rooms on the general wards of a large tertiary care hospital over a 1-year period. Patients were classified as having ALI or ARDS if they met consensus definitions for the syndromes. Characteristics and outcomes were compared to those of other patients who had been admitted to a respiratory isolation room with infiltrating lung disease but lacking bilateral infiltrates, hypoxemia, or both.

RESULTS

Of 715 patients admitted to respiratory isolation rooms on general wards, 474 (66%) had acute infiltrates. ALI criteria were met by 9% of patients (62 of 715 patients), with 2% of patients (15 of 715) satisfying the criteria for ARDS. Respiratory distress was present in 71% of ALI patients (44 of 62 patients) and 32% of patients (130 of 412 patients) with acute infiltrates who did not have ALI (p < 0.001). However, the 90-day survival rates (ALI patients, 88%; patients with acute infiltrates who did not have ALI, 90%) was similar between the two groups (p > 0.50).

CONCLUSIONS

ALI and ARDS may be frequent among patients who are admitted to respiratory isolation beds outside of ICUs. Mortality rates are substantially lower than those typically reported from surveys of ventilated ICU patients with ALI and ARDS.

Discrepant results between pyrazinamide susceptibility testing by the reference BACTEC 460TB method and pncA DNA sequencing in patients infected with multidrug-resistant W-Beijing Mycobacterium tuberculosis strains

BACKGROUND

Mycobacterium tuberculosis strains belonging to the W-Beijing family have received broad clinical and public health attention because of their rapid worldwide spread and their frequent association with outbreaks, multidrug resistance, and treatment failures and relapses.

METHODS

The present study examined a large number of multidrug-resistant strain-W isolates (isolates of 29 patients) by susceptibility testing for pyrazinamide (PZA) using the reference BACTEC 460TB method (Becton Dickinson Diagnostic Instrument Systems; Sparks, MD) and also by DNA sequencing of the pncA gene.

RESULTS

We found that despite of the presence of a strain W-specific Thr47Ala in the pncA gene, all strains showed susceptibility to PZA in the reference BACTEC 460TB system due to their higher minimum inhibitory concentrations (relative to BACTEC 460TB PZA-susceptible strains).

CONCLUSIONS

Our results suggest that the current radiometric reference method cannot reproducibly detect PZA resistance in patients infected with W-Beijing strains. Therefore, PZA susceptibility testing should instead be based on analysis of the pncA gene for resistance-associated mutations.

Cellular immune response to pulmonary infections in HIV-infected individuals hospitalized with diverse grades of immunosuppression

The lymphocyte profile of 521 HIV-infected subjects hospitalized at Jackson Memorial (2001-2002) was compared across main respiratory diseases. Study data included medical history and all laboratory evaluations performed during hospitalization. Community-acquired pneumonias (CAP, 52%), Pneumocystis jiroveci pneumonia (PCP, 24%), tuberculosis (TB, 9%) and non-tuberculous mycobacterial diseases (NTM, 12%) were the most frequent causes of admission. Patients hospitalized with PCP and NTM exhibited the lowest CD4 counts (P=0.003). PCP patients had the highest B-cell percentages (P=0.04). CAP patients had the highest CD8 and CD4 percentages and the lowest percentage of Natural Killer (NK) cells and viral burdens. TB patients exhibited the lowest NK-cell (11.4+/-6.3) and B-cell percentages (13.6+/-12) and the highest CD8 (59+/-14) percentage. NTM patients, in contrast, had the highest NK-cell percentages of the groups (19.1+/-11.6, P=0.01). Additionally, immune responses associated with respiratory pathogens differed in HIV-infected patients with CD4(+) cells above and below 200 counts.

Non-tuberculous mycobacteria disease as a cause of hospitalization in HIV-infected subjects

OBJECTIVES

The present study characterized and determined the prevalence of mycobacterial diseases (tuberculosis (TB) and non-tuberculous mycobacteria (NTM)) as a cause of hospitalization among HIV-infected subjects consecutively admitted to a large metropolitan hospital during 2001/2002.

METHODS

Hospital discharge diagnoses were established for 521 HIV-positive patients.

RESULTS

Respiratory disease accounted for 49% of the admissions. Community acquired pneumonia (CAP) was the main cause of respiratory disease (52%) followed by Pneumocystis carinii (PCP, 24%), non-tuberculous mycobacteria (NTM, 11%) and Mycobacterium tuberculosis (TB, 9%). Mycobacterium tuberculosis disease was established using bacteriological, clinical and radiographic criteria. NTM disease was defined following the American Thoracic Society criteria. NTM was disseminated in the majority of cases (19 Mycobacterium avium complex (MAC), one Mycobacterium kansasii). Nine patients had respiratory disease (seven MAC, one Mycobacterium fortuitum, one Mycobacterium kansasii) and one had gastrointestinal disease caused by MAC. Mortality was 10% for NTM disseminated cases; none of the TB patients died over the course of the study. The length of hospitalization for NTM patients was longer (15+/-13 days) than for other respiratory cases (10+/-10, p=0.04).

CONCLUSIONS

NTM disease along with its related mortality is a significant pathology as a cause of hospitalization among HIV-infected individuals.

Increased risk of Pneumocystis carinii and community-acquired pneumonia with tobacco use in HIV disease

OBJECTIVES

Tobacco smoking-related diseases continue to be of great health concern for the public, in general, and may be particularly deleterious for immunosuppressed HIV-positive individuals, who exhibit widespread tobacco use.

METHODS

A total of 521 HIV-infected subjects consecutively admitted to Jackson Memorial Hospital between 2001-2002 were enrolled in the study. Research data included a medical history, details of tobacco and illicit drug use and complete computerized hospital information. Blood was drawn to obtain T lymphocyte profiles and viral load levels. Statistical analysis methods included Pearson, Student's t- and Chi-square tests and SAS Proc CATMOD.

RESULTS

Tobacco use was prevalent, with 65% of the 521 HIV-positive hospitalized patients being current smokers. Overall, current tobacco users reported smoking an average of 15+/-13 cigarettes per day for an average of 15+/-14 years, with 40% smoking more than one pack per day. Pulmonary infections accounted for 49% of the total hospital admissions: 52% bacterial pneumonias, 24% Pneumocystis carinii pneumonia (PCP), 12% non-tuberculous mycobacterial diseases (NTM), 11% tuberculosis and 1% bronchitis. Many of the respiratory patients (46%) had been on highly active antiretroviral therapy (HAART) for over six months and 42% had received PCP and/or NTM prophylaxis. After matching the cases by HAART and CDC stage, the hazardous risk of being hospitalized with a respiratory infection was significantly higher for smokers than non-smokers (95% CI 1.33-2.83; p=0.003). Respiratory infections were noted in (37%) of the HAART-treated patients, and most (67%) occurred in smokers. CATMOD analyses controlling for HAART, viral load and CD4, indicated that HIV-infected smokers were three times more likely to be hospitalized with PCP and twice as likely to be hospitalized with community-acquired pneumonia than non-smokers, with increased risk related to the number of cigarettes/day in a dose-dependent manner.

CONCLUSIONS

Tobacco use, which is widespread among HIV-infected subjects, increases the risk of pulmonary diseases, particularly PCP and CAP, two respiratory infections with high prevalence and morbidity risks even in the era of HAART.

Pharmacokinetics of ethambutol in children and adults with tuberculosis

SETTING

Five hospitals in the United States.

OBJECTIVE

To describe ethambutol pharmacokinetics in children and adults with active tuberculosis (TB).

DESIGN

Prospective, open-labeled study in 56 adults and 14 children with active tuberculosis who received ethambutol as part of their multidrug TB regimens.

RESULTS

Most serum samples were collected up to 10 h post dose and assayed using a validated gas chromatography assay with mass selective detection (GC/MS). Concentration data were analyzed using non-compartmental and population pharmacokinetic methods. Drug exposure increased with dose, but less than proportionally at doses >3000 mg. Lower than expected maximum serum concentrations (Cmax <2 microg/ml) were common in adults. Very low Cmax (<1 microg/ml) were common in children, as was delayed absorption (time to Cmax >3 h). Many Cmax were at or below typical TB minimal inhibitory concentrations. Cmax values for HIV-positive patients were 20% lower than HIV-negative patients with daily doses, but were similar with larger twice-weekly doses.

CONCLUSIONS

Adult TB patients often had lower than expected ethambutol serum concentrations, and most pediatric TB patients had very low ethambutol serum concentrations. Higher doses and therapeutic drug monitoring may be indicated for many of these patients.

Impact of tobacco use on the development of opportunistic respiratory infections in HIV seropositive patients on antiretroviral therapy

The increased risk of developing lung diseases in cigarette smokers has been well recognized. The association between smoking and the risk of developing pulmonary infections in HIV-1-infected patients, however, which has not been established, was evaluated in the present study. Twenty-seven cases with lower respiratory infections (15 Pneumocystis carinii pneumonia (PCP), 12 TB cases) were compared with 27 age, gender, socio-economic and HIV status-matched patients, without history of respiratory diseases. Medical history and physical examinations were obtained every 6 months. Blood was drawn for CD4 and viral load measurements. A substantial number of HIV + smokers who developed PCP (one-third) had been on highly active retroviral therapy (HAART) for more than 6 months and prophylaxis had been discontinued. Multivariate analyses indicated that in HIV-infected people, after controlling for HIV status and antiretrovirals, cigarette smoking doubled the risk for developing PCP (p = 0.01). Multivariate analyses demonstrated that long-term smoking also increased the risk (2 x) of developing tuberculosis (p = 0.04). Moreover, daily tobacco use seemed to attenuate by 40% the immune and virological response to antiretroviral therapies. These findings indicate that tobacco use significantly increases the risk of pulmonary diseases in HIV infected subjects and has a potential deleterious impact on antiretroviral treatment.

Short-course rifamycin and pyrazinamide treatment for latent tuberculosis infection in patients with HIV infection: the 2-year experience of a comprehensive community-based program in Broward County, Florida

OBJECTIVES

To determine the completion rate and tolerability of short-course rifamycin and pyrazinamide treatment of latent tuberculosis infection (LTBI) in HIV-infected patients through a comprehensive community-based program.

DESIGN

Prospective cohort, with comparison to a historical control group.

PATIENTS

Of 3,118 patients with HIV infection screened for LTBI between February 1999 and March 2001, 135 patients were placed on rifamycin/pyrazinamide for 2 months under directly observed therapy and were compared to a historical group comprised of 93 HIV-infected patients who were placed on self-administered treatment of isoniazid for 12 months between 1996 and 1998.

RESULTS

Of 135 patients receiving rifamycin/pyrazinamide, 124 patients (92%) completed treatment; 5 patients had to discontinue treatment due to side effects (allergic skin reactions [n = 4], hepatitis [n = 1]). The completion rate of the historical group who received isoniazid therapy was 61% (57 of 93 patients; p < 0.001); none of those who received isoniazid experienced significant side effects.

CONCLUSION

In our experience, a comprehensive, community-based program of rifamycin/pyrazinamide for LTBI achieved significantly higher adherence than that of traditional isoniazid therapy, and thus may provide improved tuberculosis prevention in a community with high prevalence of HIV-infected patients.

Ofloxacin population pharmacokinetics in patients with tuberculosis

SETTING

Two tuberculosis hospitals in the United States.

OBJECTIVE

To determine the population pharmacokinetic (PK) parameters of ofloxacin following multiple oral doses.

DESIGN

A total of 73 patients with tuberculosis (TB) participated in the study. Subjects received multiple doses of ofloxacin as part of their treatment. They also received concurrent medications based on in vitro susceptibility data. Serum samples were collected over 10 h and assayed by a validated high performance liquid chromatography (HPLC) assay. Concentration-time data were analyzed using population methods.

RESULTS

Ofloxacin concentrations increased linearly with increasing oral doses. Delayed absorption was seen at least once in 29% of patients. Ofloxacin elimination decreased with declining renal function and increasing age. Higher daily doses were well tolerated, and appeared to maximize the peak concentration to minimal inhibitory concentration ratio (Cmax:MIC).

CONCLUSION

Ofloxacin PK parameters were comparable to those previously published for other patient populations. Higher daily doses may offer pharmacodynamic advantages for the treatment of TB.

Population pharmacokinetic modeling of pyrazinamide in children and adults with tuberculosis

STUDY OBJECTIVE

To determine population pharmacokinetic parameters of pyrazinamide after multiple oral doses given to children and adults with tuberculosis.

DESIGN

Prospective, multiple-dose population pharmacokinetic study.

SETTING

Five hospitals in the United States.

PATIENTS

Sixty-seven adults and 23 children with active tuberculosis.

INTERVENTION

The 90 patients received multiple oral doses of pyrazinamide as part of their treatment, based on the best clinical judgment of the attending physicians and in keeping with standard clinical practices at each institution. The patients also received other antituberculosis drugs empirically or based on in vitro susceptibility data.

MEASUREMENTS AND MAIN RESULTS

Serum samples were collected over 12 hours after dosing and were assayed with a validated gas chromatography assay with mass selective detection. Concentration-time data were analyzed by using population methods. Pyrazinamide concentrations increased linearly with increasing oral doses (185-3550 mg). Median maximum serum concentration values were 41.0 microg/ml with daily dosing and 66.1 microg/ml with larger, twice-weekly dosing. Incomplete (18%) or delayed (30%) absorption was more common in children than in adults (1% for each). Pharmacokinetic parameters of pyrazinamide were independent of human immunodeficiency virus status and patient demographics, except for body weight. Population elimination half-life values in pediatric and adult patients were 3.5 and 6.0 hours, respectively. Median volume of distribution (L/kg) was 32% larger in children, and median clearance (L/hr/kg) was 106% larger in children, with a resultant median half-life 43% shorter in children.

CONCLUSION

Pyrazinamide concentrations and most pharmacokinetic parameters were comparable to those previously published. Apparent half-life was somewhat shorter than that in previous reports. Compared with adults, absorption of pyrazinamide in children appeared more likely to be incomplete or delayed.

Treatment experience of multidrug-resistant tuberculosis in Florida, 1994-1997

OBJECTIVE

To study the clinical characteristics and results of patients with diagnoses of multidrug-resistant tuberculosis (MDR-TB) in the state of Florida.

METHODS

Retrospective chart review of all patients (n = 81) with diagnoses of MDR-TB in Florida between January 1, 1994, and July 31, 1997.

RESULTS

The average number of resistant drugs was 4.8 (range, 2 to 11). Of 81 patients, 46 patients (57%) completed adequate therapy, 26 patients (32%) died, and 9 patients (11%) never completed a satisfactory course of treatment. Patients who received at least part of their therapy at A. G. Holley State Hospital, a specialized tuberculosis (TB) treatment center, had significantly higher treatment completion rates (79%) than those treated as outpatients alone (48% treatment completion rate, p < 0.001), even after the exclusion of patients who were acutely ill and died within 2 months of diagnosis.

CONCLUSION

In Florida, a specialized TB care program for MDR-TB, including at least partial inpatient therapy, yielded higher treatment completion rates compared to outpatient treatment alone.

Tuberculosis recurrence: multivariate analysis of serum levels of tuberculosis drugs, human immunodeficiency virus status, and other risk factors

We examined risk factors for tuberculosis recurrence in patients admitted to a tuberculosis hospital in Florida in 1996 and 1997. Recurrence of tuberculosis was not significantly associated with tuberculosis drug levels or HIV status, which indicates that routine drug monitoring may not be beneficial in general patient management.

Use of rifabutin with protease inhibitors for human immunodeficiency virus-infected patients with tuberculosis

Drug interactions between rifamycins and highly active antiretroviral therapy (HAART) have raised concerns in the treatment of human immunodeficiency virus (HIV)-infected patients with tuberculosis. We conducted a study of this interaction by measuring serum drug levels of all HIV-infected patients with tuberculosis who were admitted to A. G. Holley State Tuberculosis Hospital (Florida) from October 1997 through December 1998, who were concomitantly treated with rifabutin and HAART. All 25 patients studied became culture-negative within 2 months of initiation of therapy for tuberculosis and remained negative for a median of 13 months follow-up after completion of therapy. HIV viral loads (mean+/-SEM) decreased significantly from 4.95+/-0.21 log10 copies/mL before initiation of HAART to 2.77+/-0.07 log10 copies/mL before discharge (P<.001); 20 of 25 patients achieved viral loads of <500copies/mL. In summary, the concomitant use of rifabutin and HAART can lead to successful treatment of HIV-infected patients with tuberculosis without increased side effects.

Phthisiology at the dawn of the new century

Tuberculosis (TB) has been and continues to be one of the most significant pathogens in terms of human morbidity and mortality. Although the resurgence of TB has been held in check in most developed countries, the epidemic rages on in most developing countries of the world. The specter of drug resistance is becoming a more credible challenge in many parts of the world, dimming the prospects of eventual elimination. However, great opportunities are arising as well, with an unprecedented focus on the global aspects of TB control. This article will review the status of TB today and put into perspective the prospects for its elimination in the coming century.

Mesothelial cells in tuberculous pleural effusions of HIV-infected patients

The scarcity of mesothelial cells is a well-known characteristic of tuberculous pleural effusions. We report three HIV-infected patients with tuberculous pleural effusions, in which mesothelial cells were found in significant numbers in the pleural fluid. Clinicians should be aware that the altered immune responses that occur in HIV-infected patients may affect the cytologic profile of tuberculous pleural effusions, and they should be cautious not to exclude this diagnosis based solely on the presence of mesothelial cells in the fluid.

Pulmonary tuberculosis in AIDS patients: transient chest radiographic worsening after initiation of antiretroviral therapy

OBJECTIVE

Immune function and inflammatory responses often increase in AIDS patients who receive antiretroviral therapy. We evaluated the occurrence and nature of transient worsening on chest radiographs in AIDS patients with tuberculosis after initiation of antiretroviral therapy and compared these findings with chest radiographs of patients undergoing antituberculous therapy alone.

MATERIALS AND METHODS

A retrospective review of sequential chest radiographs was performed of 87 patients undergoing therapy for pulmonary tuberculosis: AIDS patients receiving antiretroviral therapy (n = 31), HIV-positive patients not receiving antiretroviral therapy (n = 26), and HIV-negative patients (n = 30). Pulmonary consolidations, thoracic lymphadenopathy, and pleural effusions were evaluated for worsening, stability, or improvement. Patients with concurrent pulmonary infections were excluded.

RESULTS

Transient worsening on radiography was observed in 14 (45%) of 31 AIDS patients receiving antiretroviral therapy, including seven patients (23%) who showed severe worsening. Of 56 patients in the other two groups, 11 (20%) showed worsening (p = 0.023), two of whom showed severe worsening (p = 0.009). Worsening was first noted between 1 and 5 weeks after initiation of antiretroviral therapy, with improvement occurring between 2 weeks and 3 months later. Four patients with severe worsening converted their tuberculin purified protein derivative responses from anergic to positive after antiretroviral treatment.

CONCLUSION

Transient worsening is frequently seen on chest radiography in AIDS patients with tuberculosis who subsequently undergo antiretroviral therapy. This phenomenon may be related to improved immune function.

Paradoxical worsening of tuberculosis following antiretroviral therapy in patients with AIDS

Transient worsening of tuberculous symptomatology and lesions following antituberculous therapy (paradoxical response) has previously been described as a rare occurrence. To determine the incidence of paradoxical responses in patients with AIDS and TB who are treated with antituberculous therapy and subsequently with combination antiretroviral therapy (ARV), we conducted a prospective study of 33 HIV-seropositive TB patients treated with anti-TB therapy and antiretroviral therapy (Group 1) compared with 55 HIV-seronegative TB patients treated with anti-TB therapy (Group 2) and 28 HIV-seropositive TB patients treated with anti-TB therapy but not on antiretrovirals (historical control; Group 3). In Group 1 patients, paradoxical responses were temporally more related to the initiation of ARV than to the initiation of anti-TB therapy (mean +/- SD: 15 +/- 11 d versus 109 +/- 72 d [p < 0.001]) and occurred much more frequently (12 of 33; 36%) compared with Group 2 (1 of 55; 2%) (p < 0.001) or with Group 3 (2 of 28; 7%) (p = 0.013). The majority of patients who experienced paradoxical responses and received tuberculin purified protein derivative (PPD) in Group 1 had their tuberculin skin tests convert from negative to strongly positive after ARV. These observations suggest that a paradoxical response associated with enhanced tuberculin skin reactivity may occur after the initiation of ARV in HIV-infected TB patients. Furthermore, the skin test conversion after the initiation of ARV may have important public health implications.

Antituberculosis drug-induced hepatotoxicity. The role of hepatitis C virus and the human immunodeficiency virus

Until recently it was thought that age greater than 35 yr was the main risk factor for the development of drug-induced hepatitis (DIH) in patients receiving antituberculosis therapy. We conducted a study to determine whether infection with either the hepatitis C virus or the human immunodeficiency virus (HIV) were significant risk factors for the development of DIH in patients receiving antituberculosis therapy. Our study consisted of two parts. In the first part, 134 consecutive patients admitted for the treatment of tuberculosis (TB) were followed for the development of DIH. All of these patients were also screened for the presence of hepatitis C and HIV. In the second part of the study, those patients who were hepatitis C positive and who developed DIH on repeated reintroduction of the anti-TB drugs were offered a liver biopsy. If active inflammation, which may be suggestive of hepatitis C infection, was present on the biopsy specimen, treatment with alpha-interferon was begun and the anti-TB drugs were subsequently reintroduced. During the 18 mo of the study, 22 patients developed DIH. The relative risk of developing DIH if the patient was hepatitis C or HIV positive was fivefold and fourfold, respectively (p < 0.05). If a patient was coinfected with both hepatitis C and HIV the relative risk of developing DIH was increased 14.4-fold (p < 0.002). In the treatment part, four patients were treated with alpha-interferon, and all were able to undergo the reintroduction of anti-TB therapy without reoccurrence of DIH. Infection with hepatitis C and HIV are independent and additive risk factors for the development of DIH during TB therapy. The treatment of hepatitis C with alpha-interferon may allow the reintroduction of anti-TB agents in those who previously developed DIH when exposed to these drugs.

Inhibition of antigen-induced acute bronchoconstriction, airway hyperresponsiveness, and mast cell degranulation by a nonanticoagulant heparin: comparison with a low molecular weight heparin

Inhaled heparin prevents antigen-induced bronchoconstriction and inhibits anti-IgE-mediated mast-cell degranulation. We hypothesized that the antiallergic action of heparin may be dependent on molecular weight and related to its nonanticoagulant properties. Therefore, in the present investigation we studied the effects of a nonanticoagulant fraction of heparin (LA-heparin) on antigen-induced bronchoconstriction, airway hyperresponsiveness (AHR), and mast-cell degranulation, and compared its antiallergic activity with that of a low molecular weight heparin (LMW-heparin, fragmin). Specific lung resistance (SRL) was measured in 15 sheep before, immediately after, and serially for as long as 2 h after airway challenge with Ascaris suum antigen, without and after pretreatment with inhaled fractionated heparins at doses of 2.5 and 5 mg/kg. Airway responsiveness was estimated before, and 2 h after antigen as the cumulative provocating dose (PD400) of carbachol in breath units, which increased SRL by 400% (one breath unit was defined as one breath of 1% carbachol solution). LA-heparin caused a dose-dependent inhibition of antigen-induced bronchoconstriction, and a 5-mg/kg nebulized dose caused a 67% inhibition of allergic bronchoconstriction, whereas a 2.5-mg/kg dose was ineffective (20% inhibition). Inhaled fragmin was more potent than LA-heparin, as shown by 84% (2.5 mg/kg) and 82% (5 mg/kg) inhibition of allergic bronchoconstriction. Fragmin (5 mg/kg) also attenuated the postantigen AHR, whereas LA-heparin was ineffective. In vitro, preincubation with both LA-heparin and fragmin inhibited the anti-IgE-induced degranulation of rat peritoneal mast-cells in a dose-dependent fashion. LA-heparin was fourfold more potent than fragmin, with IC50 of 80 and 320 microg/ml, respectively. These data suggest that: (1) fractionated heparins attenuate antigen-induced acute bronchoconstriction, (2) nonanticoagulant fractions mediate the antiallergic activity of inhaled heparin, and (3) antiallergic activity of nonanticoagulant heparin and LMW-heparin may be related to prevention of mast-cell degranulation.