A novel home-based method for preparing suspensions of anti-TB drugs

BACKGROUND: Tablets are the most widely available dosage form for the treatment of TB; however, adult tablets fail to meet the needs of young children who cannot swallow these tablets or require dose titration. We tested a new, simple device (XTEMP-R®) and the methodology for converting tablets of TB drugs into a homogeneous suspension for home use by children and caregivers.METHODS: XTEMP-R is a new device used for converting tablets into liquid preparations. Four TB drugs - pretomanid, delamanid, clofazimine and bedaquiline - were dispersed in the device utilizing water and simple syrup. The reproducibility of accurately delivering aliquots from the suspension upon preparation and upon redispersion after storing for 2 days was studied.RESULTS: Suspensions of each of the drugs tested were easily prepared in about 10 min and were visually uniform in consistency. Dosages in 2 and 5 mL were assessed in suspension, and those in 5 mL tested upon redispersion after 2 days. The observed range for these dosages spanned from 94.6% to 101.1% of the theoretical concentration for the suspensions under examination. The cleaned device had no detectable residual drug.CONCLUSION: XTEMP-R can be used at home by caregivers to prepare doses of suspensions accurately for children and patients who cannot swallow tablets.

Clinical standards for drug-susceptible TB in children and adolescents

BACKGROUND: These clinical standards aim to provide guidance for diagnosis, treatment, and management of drug-susceptible TB in children and adolescents.METHODS: Fifty-two global experts in paediatric TB participated in a Delphi consensus process. After eight rounds of revisions, 51/52 (98%) participants endorsed the final document.RESULTS: Eight standards were identified: Standard 1, Age and developmental stage are critical considerations in the assessment and management of TB; Standard 2, Children and adolescents with symptoms and signs of TB disease should undergo prompt evaluation, and diagnosis and treatment initiation should not depend on microbiological confirmation; Standard 3, Treatment initiation is particularly urgent in children and adolescents with presumptive TB meningitis and disseminated (miliary) TB; Standard 4, Children and adolescents should be treated with an appropriate weight-based regimen; Standard 5, Treating TB infection (TBI) is important to prevent disease; Standard 6, Children and adolescents should receive home-based/community-based treatment support whenever possible; Standard 7, Children, adolescents, and their families should be provided age-appropriate support to optimise engagement in care and clinical outcomes; and Standard 8, Case reporting and contact tracing should be conducted for each child and adolescent.CONCLUSION: These consensus-based clinical standards, which should be adapted to local contexts, will improve the care of children and adolescents affected by TB.

Children´s priorities to improve the acceptability of MDR-TB treatment: qualitative data from South Africa

BACKGROUND: Multidrug-resistant TB (MDR-TB) treatment for children frequently includes unpalatable drugs with low overall acceptability. This can negatively impact children and their caregivers´ treatment experiences and is an important contributor to poor adherence, and potentially, poor treatment outcomes. Children and their caregivers´ preferences for MDR-TB treatment are not well documented. We describe children and caregivers´ priorities to inform future MDR-TB treatment regimens.METHODS: We conducted a cross-sectional qualitative study at a TB hospital in South Africa using semi-structured interviews and participatory research activities with caregivers and children routinely diagnosed and treated for MDR-TB between June and August 2018.RESULTS: We conducted 15 interviews with children and their caregivers. Children ranged from 2 to 17 years of age (median age: 8.3 years). Children and caregivers had an overall negative experience of MDR-TB treatment. Children and caregivers described how future MDR-TB drugs and regimens should prioritise sweeter flavours, fewer pills, brighter colours, and formulations that are easy to prepare and administer and dispensed in colourful, small and discrete packaging.CONCLUSIONS: MDR-TB treatment acceptability remains low, and negatively impacts children and their caregivers´ treatment experiences. Improving the overall acceptability of MDR-TB treatment requires engaging with children and their caregivers to better understand their priorities for new treatment regimens and child-friendly formulations.

Stable, compounded bedaquiline suspensions to support practical implementation of pediatric dosing in the field

BACKGROUND: Bedaquiline (BDQ) tablets are indicated as part of a combination regimen for the treatment of multidrug-resistant TB in adults, adolescents and children. A dispersible tablet formulation is now approved but is not currently available in all settings. The aim of this study was to develop stable extemporaneous liquid formulations of BDQ that can be stored at room temperature or 30°C for several weeks, to support pragmatic pediatric dosing in the field and reduce wastage.METHODS: BDQ tablets were suspended in simple syrup and a sugar-free vehicle. Each 20 mg/mL formulation was stored at room temperature or 30°C for 30 days in amber dispensing bottles. Appearance, BDQ potency, pH and microbial counts were determined on Days 0, 15 and 30.RESULTS: The BDQ potency in both formulations remained at 98-101% of the theoretical concentration for 30 days. The appearance, pH and microbial count of sugar-free formulation did not change during the 30-day storage. The simple syrup formulation was stable for 15 days as microbial growth was observed on Day 30.CONCLUSIONS: BDQ may be prepared in syrup or sugar-free suspensions: syrup suspensions can be stored for 15 days at room temperature and 30C, whereas sugar-free suspensions can be stored for 30 days at room temperature and 30C. This information will support practical BDQ dosing for children in the field.

Extemporaneously compounded liquid formulations of clofazimine

BACKGROUND: Clofazimine (CFZ) is routinely used worldwide for the treatment of leprosy and TB. However, no liquid or dispersible tablet formulations of CFZ are currently available commercially for patients with challenges ingesting soft gelatin capsules or solid formulations. The aim of this research was to develop stable extemporaneous liquid formulations of CFZ that can be stored at room temperature for several weeks to enable practical dosing in the field.METHODS: Two formulations were prepared in syrup and sugar-free vehicles with CFZ tablets using a simple method that can be used in a routine pharmacy. Suspensions were stored at room temperature and at 30°C for 30 days. Formulation aliquots were tested on Days 0, 15 and 30 for appearance, pH, potency and microbial counts.RESULTS: Appearance remained unchanged during storage. The pH of both formulations was between 4.0 and 6.0. Potency was between 90% and 110% for 30 days in the syrup formulation and for 15 days in the sugar-free formulation. Microbial counts met United States Pharmacopeia <1111> limits for oral aqueous liquids and specific organisms were absent.CONCLUSIONS: A simple field-friendly method was successfully developed for the preparation of CFZ liquid formulations using commonly available ingredients. This will permit practical dosing and titration for children and other patients with swallowing challenges.

Sugar and sugar-free liquid formulations of delamanid for patients with rifampicin-resistant TB

BACKGROUND: Delamanid (DLM) tablets are recommended for the treatment of rifampicin-resistant TB. However, no liquid or dispersible tablet formulation of DLM is currently commercially available for patients with challenges ingesting these tablets. The aim of this study was to develop stable extemporaneous liquid formulations of DLM that can be stored at room temperature for several weeks.METHODS: DLM tablets were suspended in 1) simple syrup and 2) a specially formulated sugar-free vehicle. These suspensions containing DLM 5 mg/mL were stored in plastic prescription bottles at room temperature or 30°C for 30 days. These suspensions were evaluated for appearance, potency, pH, and microbial counts at Days 0, 15, and 30.RESULTS: The potency of DLM in each formulation remained at 98-104% of the theoretical concentration for 30 days. The appearance, pH, and microbial count did not change for the sugar-free formulation during the 30-day storage period. Microbial growth, however, was observed in the simple syrup formulation on Day 30 but not on Day 15.CONCLUSION: DLM can be formulated in sugar or sugar-free suspensions and stored at room temperature or 30°C for at least 15 and 30 days, respectively.

Stable sugar and sugar-free suspensions of pretomanid

BACKGROUND: Pretomanid (PMD) tablets are indicated as part of a combination regimen for the treatment of adults with pulmonary extensively drug-resistant, treatment-intolerant or non-responsive multidrug-resistant TB. No commercial liquid formulation is currently available for patients unable to swallow these tablets.OBJECTIVE: To develop stable extemporaneous liquid formulations of PMD that can be stored at room temperature or 30°C for at least 4 weeks.METHODS: Crushed PMD tablets were formulated into 20 mg/mL suspensions in a simple syrup and sugar-free formulation. The PMD formulations were stored at room temperature and at 30°C for 30 days in dispensing bottles. Appearance, pH, potency and microbial counts of the suspensions were determined on Days 0, 15 and 30.RESULTS: The potency of PMD remained at 99.7-103.4% of the theoretical concentration in each formulation. The appearance, pH and microbial count did not change during the 30-day storage period. Simple syrup formulations did not require preservatives for microbial stability.CONCLUSIONS: PMD oral suspension formulations in simple syrup or in sugar-free vehicle were easily prepared by utilising commonly available equipment and ingredients and were stable for 30 days. These formulations are appropriate alternatives for patients with swallowing difficulties.

Treatment outcomes and safety in children with rifampicin-resistant TB

BACKGROUND: The treatment of rifampicin-resistant TB (RR-TB) in children is evolving rapidly. As newer regimens are introduced into routine care, it is vital to compare their outcome and safety with well-characterised clinical cohorts treated with historical regimens.METHODS: Study sample comprised a prospective observational cohort of children on routine RR-TB treatment, enrolled from 2011 to 2015 in Cape Town, South Africa. Children were followed for safety, treatment response and outcome.RESULTS: Of 136 children included, 27 (19.9%) were living with HIV and 48 (37.8%) had severe TB. The median time-to-culture conversion in children with bacteriological confirmation (n = 44) was 28.5 days (IQR 14.5-45). Overall, 118/129 (91.5%) had favourable TB treatment outcomes. Of 106 (77.9%) children who received an injectable drug, 9 (8.5%) developed hearing loss and 7/136 (5.1%) developed other Grade 3 or higher adverse events likely related to treatment.CONCLUSIONS: In this cohort with a substantial proportion of children with severe manifestations of TB and with HIV, TB treatment outcomes were excellent. Apart from hearing loss, few children developed severe adverse events related to treatment. This study provides robust reference data for future evaluation of shorter, injectable-sparing regimens.

Pharmacokinetics of high-dose isoniazid in children affected by multidrug-resistant TB

BACKGROUND: High-dose isoniazid (INH^H) (15-20 mg/kg/day) could be administered to overcome low-level INH resistance, but pharmacokinetic data are sparse.METHODS: This observational study included South African children (<15 years) receiving INH^H as preventive therapy, or treatment for multidrug-resistant TB (MDR-TB) exposure or disease. Pharmacokinetic sampling was performed after an INH dose of 20 mg/kg. Non-compartmental analysis and multivariable regression models were used to evaluate associations of key covariates with area under the curve (AUC_0-24) and maximum concentration (C_max). AUC and C_max values were compared against proposed adult targets.RESULTS: Seventy-seven children were included, with median age of 3.7 years; 51 (66%) had MDR-TB disease and 26 (34%) had MDR-TB exposure. Five were HIV-positive, of whom four were ≥5 years old. The median AUC_0-24 was 19.46 µgh/mL (IQR 10.76-50.06) and C_max was 5.14 µg/mL (IQR 2.69-13.2). In multivariable analysis of children aged <5 years, MDR-TB disease (vs. exposure) was associated with considerably lower AUC_0-24 (geometric mean ratio GMR 0.19, 95% CI 0.15-0.26; P < 0.001) and C_max (GMR 0.20, 95% CI 0.15-0.26; P < 0.001).CONCLUSIONS: INH concentrations in children with MDR-TB disease were much lower than expected, but comparable to previous reports in children with MDR-TB exposure. Further studies should confirm these findings and explore possible causes.

A novel approach for eliciting adolescent MDR-TB treatment tolerability: qualitative data from South Africa

SETTING: Treatment tolerability among adolescents diagnosed with multidrug-resistant tuberculosis (MDR-TB) is underexplored. We present qualitative study data from adolescents participating in an observational cohort in the Western Cape, South Africa.OBJECTIVE: To elicit adolescent experiences of MDR-TB diagnosis and treatment with qualitative body-mapping activities and discussions.DESIGN: Adolescents in an observational MDR-TB cohort received routine toxicity and audiology screenings from clinicians. We enrolled eight participants (age 10-16 years) to participate in additional body-mapping activities and in-depth interviews. A thematic deductive analysis was conducted. We present a comparison of the clinical assessments and qualitative discussions.RESULTS: Adolescent participants reported few adverse effects on standard toxicity and audiology reports. Only nausea and vomiting were reported in >10% of cases, all of which were grade 1 (causing no/minimal interference) adverse effects (AEs). However, when comparing toxicity reports with qualitative body-mapping activities and interviews, we found previously unreported AEs (neurosensory alteration, neuromuscular weakness, pain); underestimated severity of AEs (nausea, itching); and missed psychosocial symptoms (signs of depression).CONCLUSION: Adolescents receiving treatment for MDR-TB experienced treatment-related AEs that were not reported during routine clinical assessments. Psychosocial experiences of adolescents are not taken into account. More research is needed to understand the experiences of this vulnerable group. We recommend that drug safety monitoring be adapted to include more creative and patient-driven reporting mechanisms for vulnerable groups, including children.

Current status of pharmacokinetic and safety studies of multidrug-resistant tuberculosis treatment in children

After decades of neglect, data are finally becoming available on the appropriate, safe dosing of key second-line anti-tuberculosis drugs used for treating multidrug-resistant tuberculosis (MDR-TB) in children, including levofloxacin (LVX), moxifloxacin (MFX), linezolid (LZD) and delamanid (DLM). Much needed data on some novel and repurposed drugs are still lacking, including for bedaquiline (BDQ), pretomanid (PTM) and clofazimine (CFZ). We review the status of pharmacokinetic (PK) and safety studies of key anti-tuberculosis medications in children with MDR-TB, identify priority knowledge gaps and note ongoing work to address those gaps, in the context of planning for an efficacy trial in children with MDR-TB. There is international consensus that an efficacy trial of a novel, all-oral, shortened MDR-TB treatment trial in children is both needed and feasible. Key novel and repurposed second-line anti-tuberculosis drugs include BDQ, DLM, PTM, MFX, LVX, CFZ and LZD. The rapidly emerging PK and safety data on these medications in children with MDR-TB from studies that are underway, completed or planned, will be critical in supporting such an efficacy trial. Commitment to addressing the remaining knowledge gaps, developing child-friendly formulations of key medications, improving the design of paediatric PK and safety studies, and development of international trial capacity in children with MDR-TB are important priorities.

Conducting efficacy trials in children with MDR-TB: what is the rationale and how should they be done?

Paediatric anti-tuberculosis treatment trials have traditionally been limited to Phase I/II studies evaluating the drug pharmacokinetics and safety in children, with assumptions about efficacy made by extrapolating data from adults. However, it is increasingly being recognised that, in some circumstances, efficacy trials are required in children. The current treatment for children with multidrug-resistant tuberculosis (MDR-TB) is long and toxic; shorter, safer regimens, using novel agents, require urgent evaluation. Given the changing pattern of drug metabolism, disease spectrum and rates of TB disease confirmation with age, decisions around inclusion criteria require careful consideration. The most straightforward MDR-TB efficacy trial would include only children with confirmed MDR-TB and no additional drug resistance. Given that it may be unclear at the time treatment is initiated whether the diagnosis will ultimately be confirmed and what the final drug resistance profile will be, this presents a unique challenge in children. Recruiting only these children would, however, limit the generalisability of such a trial, as in reality the majority of children with TB do not have bacteriologically confirmed disease. Given the good existing treatment outcomes with current routine regimens for children with MDR-TB, conducting a superiority trial may not be the optimal design. Demonstrating non-inferiority of efficacy, but superiority with regard to safety, would be an alternative strategy. Using standardised control and experimental MDR-TB treatment regimens is challenging given the wide spectrum of paediatric disease. However, using variable regimens would make interpretation challenging. A paediatric MDR-TB efficacy trial is urgently needed, and with global collaboration and capacity building, is highly feasible.

Statistical considerations for pediatric multidrug-resistant tuberculosis efficacy trials

The inclusion of newly licensed or repurposed drugs in regimens to treat children for multidrug-resistant tuberculosis (TB) may lead to treatment that is shorter than traditional regimens and composed only of oral medications. As an all-oral regimen may be more acceptable and have a better safety profile than current regimens, demonstrating non-inferiority may be satisfactory. Demonstrating non-inferior efficacy requires setting a non-inferiority margin and safeguarding study assay sensitivity. Multi-arm, multistage designs may currently not be appropriate in pediatric trials because of the lack of sensitive and specific intermediate outcomes. However, including an arm with an agent to ameliorate toxicity would be efficient. Covariates can be used to stratify randomization, define subgroups, and improve efficiency of analysis. Enriching the sample for the confirmed-TB subgroup to ensure that they are well represented may be important. Primary outcomes using a fixed timepoint from randomization for all study arms will result in variations in post-treatment duration, but may be the best choice. While blinding of site personnel and patients may not be possible when regimens differ substantially in drugs and modes of administration, blinding should be maintained for independent endpoint review groups and other personnel. Type I error and family-wise error rates should be tightly controlled.

Surveillance provides insight into epidemiology and spectrum of culture-confirmed mycobacterial disease in children

BACKGROUND

Longer-term tuberculosis (TB) drug resistance surveillance among children is rare. We determined the prevalence of drug resistance among children with culture-confirmed TB from 2011 to 2013, compared these results with four previous consecutive 2-year periods and documented other mycobacterial isolates identified.

METHOD

Surveillance study of mycobacterial culture in all children aged <13 years conducted from March 2011 to February 2013 at the Tygerberg Children's Hospital, Cape Town, South Africa. Drug susceptibility testing against isoniazid (INH) and rifampicin (RMP) was performed using line-probe assay (GenoType(®) MTBDRplus). Clinical data were obtained through folder review.

RESULTS

Of 381 children, 323 (84.8%; 324 episodes) had Mycobacterium tuberculosis, 46 (12.1%) had M. bovis bacille Calmette-Guérin and 12 (3.1%) had non-tuberculous mycobacteria isolated. Forty-one (12.7%) children had M. tuberculosis resistant to INH and/or RMP; 15 (4.7%) had multidrug-resistant TB (MDR-TB). The prevalence of INH mono- or polyresistance remained stable; however, RMP monoresistance increased (0/313 in 2003-2005 vs. 6/324, 1.9%, in 2011-2013; P = 0.041); MDR-TB prevalence has declined significantly, from 26/292 (8.9%) in 2007-2009 to 15/324 (4.7%) in 2011-2013 (OR 0.50, 95%CI 0.24-0.99). The prevalence of human immunodeficiency virus co-infection has decreased significantly, from a peak of 29% to 15.3%.

CONCLUSIONS

There has been a significant reduction in bacteriologically confirmed MDR-TB cases. The increase in RMP monoresistance has important implications for treatment.

Outcome of culture-confirmed isoniazid-resistant rifampicin-susceptible tuberculosis in children

SETTING

Isoniazid-resistant rifampicin-susceptible (H^RR^S) tuberculosis (TB) is the most prevalent form of drug-resistant TB globally, and may be a risk factor for poor outcomes, but has been poorly described in children.

OBJECTIVE

To characterise the clinical presentation, treatment, and clinical and microbiological outcomes among children with culture-confirmed H^RR^S TB.

DESIGN

Retrospective hospital-based cohort study.

RESULTS

Of the 72 children included in the study, the median age was 50.1 months (IQR 21.5-102.5); 42% were male. Forty-four (51%) had a potential source case; only 13 were confirmed H^RR^S TB. Of 66 tested, 12 (17%) were human immunodeficiency virus (HIV) infected, and 36 (60%) of the 60 with pulmonary TB (PTB) had severe disease. Seventy children had treatment data; the median total duration of treatment was 11.3 months (IQR 9-12.3); 25 (36%) initiated treatment with a three-drug intensive phase; 52 (74%) received a fluoroquinolone. Of 63 children with known outcomes, 55 (88%) had a favourable outcome, 1 died and 3 had treatment failure. Ten had positive follow-up cultures at ⩾2 months after starting treatment. Older age (P = 0.008), previous anti-tuberculosis treatment (P = 0.023) and severe PTB (P = 0.018) were associated with failure to culture-convert at ⩾2 months.

CONCLUSIONS

Although overall outcomes were good, prolonged culture positivity and cases of treatment failure emphasise the need for additional attention to the management of children with H^RR^S TB.

Pediatric multidrug-resistant tuberculosis clinical trials: challenges and opportunities

On June 17, 2016, RESIST-TB, IMPAACT, Vital Strategies, and New Ventures jointly hosted the Pediatric Multidrug Resistant Tuberculosis Clinical Trials Landscape Meeting in Arlington, Virginia, USA. The meeting provided updates on current multidrug-resistant tuberculosis (MDR-TB) trials targeting pediatric populations and adult trials that have included pediatric patients. A series of presentations were given that discussed site capacity needs, community engagement, and additional interventions necessary for clinical trials to improve the treatment of pediatric MDR-TB. This article presents a summary of topics discussed, including the following: current trials ongoing and planned; the global burden of MDR-TB in children; current regimens for MDR-TB treatment in children; pharmacokinetics of second-line anti-tuberculosis medications in children; design, sample size, and statistical considerations for MDR-TB trials in children; selection of study population, design, and treatment arms for a trial of novel pediatric MDR-TB regimens; practical aspects of pediatric MDR-TB treatment trials; and strategies for integrating children into adult tuberculosis trials. These discussions elucidated barriers to pediatric MDR-TB clinical trials and provided insight into necessary next steps for progress in this field. Investigators and funding agencies need to respond to these recommendations so that important studies can be implemented, leading to improved treatment for children with MDR-TB.

Paediatric formulations of second-line anti-tuberculosis medications: challenges and considerations

There is a growing number of children worldwide accessing second-line anti-tuberculosis drugs for multidrug-resistant tuberculosis (TB); however, there are very few child-friendly formulations. For paediatric use, dispersible tablets offer distinct advantages over liquid formulations and other approaches. This is particularly relevant for TB, where stability, long shelf-life and reduced manufacturing, transport and storage costs are all critical to ensuring that drugs are accessible and affordable. In addition, fixed-dose combinations that reduce the pill burden and provide adequate taste masking may promote long-term adherence to anti-tuberculosis treatment and prevention regimens likely to last many months in children. Partial adherence may result in treatment failure and the further selection and spread of resistant mycobacteria. Unfortunately, no second-line TB paediatric drugs exist in dispersible formulations. We discuss here the main obstacles to developing such tablets and present strategies for overcoming them. We also advocate for timely anticipation of paediatric use when new TB drugs are being developed, and for the development of child-friendly anti-tuberculosis formulations in general.

A bitter pill to swallow: the need for better medications for drug-resistant tuberculosis in children

The large and growing access gap between the number of children who become sick with drug-resistant tuberculosis (DR-TB) and those who are treated for the disease each year represents a significant health systems failure. While there are multiple reasons why children with DR-TB are not diagnosed and treated, a serious challenge is the medications used to treat the disease. This paper presents three child DR-TB cases who were treated incorrectly; the cases are used to illustrate some of the problems with existing second-line medications. Challenges, including the perception that the drugs are more dangerous than the disease, lack of proper dosing recommendations and formulations, and the high cost of current treatment, all contribute to a perverse situation in which the most vulnerable pediatric patients are provided with a lower standard of care. This situation can be reversed with novel partnerships and training models, pharmacokinetic studies of the relevant drugs, increased collaboration, and dedicated funding, grounded in a rights-based approach to DR-TB in children.

Completeness and accuracy of electronic recording of paediatric drug-resistant tuberculosis in Cape Town, South Africa

SETTING

Cape Town, South Africa.

OBJECTIVE

To assess the completeness and accuracy of electronic recording of drug-resistant tuberculosis (DR-TB) in children.

DESIGN

Retrospective cohort study. All children aged <15 years treated for DR-TB during 2012 were included, with clinical data collected from routine health services. Matching was performed between clinical data and an extracted data set from an electronic register for DR-TB (EDR.web), and data sources were compared.

RESULTS

Seventy-seven children were identified clinically, of whom only 49 (64%) were found in EDR.web. Most data in EDR.web were complete and accurate, but there were some internal inconsistencies for confirmed TB. Only 4.4% of all EDR.web entries were children.

CONCLUSION

Only two thirds of children clinically treated for DR-TB were recorded in the electronic reporting system, suggesting under-reporting. We also found a lower than expected prevalence of childhood DR-TB, probably suggesting both under-diagnosis and under-recording of DR-TB in children. Clinicians at facility level should be able to access the electronic reporting system, and data transfer between clinical paper-based and electronic sources should be simplified. Cross-linking between electronic registers for drug-susceptible and DR-TB or consolidation of registers could improve the accuracy of recording. Improved recording and reporting of DR-TB in children is needed.

Children exposed to multidrug-resistant tuberculosis at a home-based day care centre: a contact investigation

SETTING

In high tuberculosis (TB) burden settings, day care centres may be an underestimated source of exposure of children to infectious drug-susceptible (DS) and drug-resistant (DR) TB cases.

OBJECTIVE

To describe the results of a contact investigation of children exposed to an adult with DR-TB at a South African home-based day care centre.

DESIGN

Retrospective descriptive community-based cohort study.

RESULTS

Mycobacterium tuberculosis resistant to isoniazid (INH), rifampicin and amikacin was cultured from the sputum of an adult index case residing in a home-based day care centre. Of 38 children aged <15 years identified during routine contact investigation, consent was obtained for 34; the median age was 3.9 years (IQR 2.9-5.2); 23/34 were aged <5 years, none were human immunodeficiency virus infected. The median contact score was 4/10, 8 had a reactive tuberculin skin test (⩾10 mm) and none had TB. Of the 34 study children, 24 received 6 months of DR-TB preventive therapy comprising ofloxacin, ethambutol and high-dose INH; 21 completed 12 months' follow-up and none developed TB.

CONCLUSIONS

TB at day care centres may result in many exposed young children with high TB contact scores, similar to household contact investigations. Active identification and initiation of preventive treatment may be able to avert DR-TB cases.

Selective modification of apoB-100 in the oxidation of low density lipoproteins by myeloperoxidase in vitro

Oxidative modification of LDL may be important in the initiation and/or progression of atherosclerosis, but the precise mechanisms through which low density lipoprotein (LDL) is oxidized are unknown. Recently, evidence for the existence of HOCl-oxidized LDL in human atherosclerotic lesions has been reported, and myeloperoxidase (MPO), which is thought to act through production of HOCl, has been identified in human atherosclerotic lesions. In the present report we describe the formation of 2,4-dinitrophenylhydrazine (DNPH)-reactive modifications in the apolipoprotein (apo) by exposure of LDL to myeloperoxidase in vitro. In contrast with the complex mixture of peptides from oxidation of LDL with reagent HOCl, oxidation with MPO in vitro produced a major tryptic peptide showing absorbance at 365 nm. This peptide was isolated and characterized as VELEVPQL(*C)SFILK..., corresponding to amino acid residues 53-66...on apoB-100. Mass spectrometric analyses of two tryptic peptides from oxidation of LDL by HOCl indicated formation of the corresponding methionine sulfoxide (M=O), cysteinyl azo (*C), RS -N= N-DNP, derivatives of EEL(*C)T(M=O)FIR and LNDLNS VLV(M=O)PTFHVPFTDLQVPS(*C)K, which suggest oxidation to the corresponding sulfinic acids (RSO2H) by HOCl. The present results demonstrate that DNPH-reactive modifications other than aldehydes and ketones can be formed in the oxidation of proteins and illustrate how characterization of specific products of protein oxidation can be useful in assessing the relative contributions of different and unexpected mechanisms to the oxidation of LDL and other target substrates. The data also suggest a direct interaction of the LDL particle with the active site on myeloperoxidase and indicate that effects of the protein microenvironment can greatly influence product formation and stability.