Drug-resistant tuberculosis: controversies and challenges in pediatrics

Low enrollment and high treatment success in children with drug-resistant tuberculosis in Ethiopia: A ten years national retrospective cohort study

Background

Limited evidence exists on the treatment outcome and factors that are associated with the duration from the initiation of treatment to death or treatment failure in children with drug resistant tuberculosis (DR-TB). Thus, we aimed to determine the proportion of treatment enrollment, status of treatment outcome and determine factors that are associated with the duration from treatment initiation to death or treatment failure in children treated for DR-TB in Ethiopia.

Methods

We conducted a retrospective cohort study in children younger than 15 years old who were treated for DR-TB from February 2009 to February 2019 in Ethiopia. We collected data on socio-demographic and clinical characteristics from clinical charts, registration books and laboratory result reports on 155 children. Proportion of enrollment to the treatment was calculated by dividing the total number of children who were receiving the treatment by the total number of DR-TB patients treated during the specified years. We used Cox proportional hazard models to determine factors that were associated with the duration from the beginning of the treatment to death or treatment failure. Data was analyzed using STATA version 14.

Results

Of the 3,478 DR-TB patients enrolled into the treatment and fulfilling our inclusion criteria during the past ten years, 155 (4.5%) were children. Of the 155 children, 75 (48.4%) completed the treatment and 51 (32.9%) were cured. Furthermore, 18 (11.6%) children were died, seven (4.5%) lost to follow up and treatment of four (2.6%) children was failed. The overall treatment success was 126 (81.3%). Age younger than 5 years old [Adjusted Hazard Ratio (AHR) = 3.2, 95%CI (1.2–8.3)], HIV sero-reactivity [AHR = 5.3, 95%CI (1.8–14.9)] and being anemic [AHR = 4.3, 95%CI (1.8–10.3)] were significantly associated with the duration from the enrollment into the treatment to death or treatment failure.

Conclusion

In this study, the proportion of children enrolled into DR-TB treatment was lower than the proportion of adults enrolled to the treatment (4.5% in children versus 95.5% in adults) in last ten years. Our findings also suggest that children with DR-TB can be successfully treated with standardized long term regimen. Further prospective cohort study is required to investigate factors contributing to death or treatment failure.

Applications of Molecular Simulation in the Discovery of Antituberculosis Drugs: A Review

After decades of efforts, tuberculosis has been well controlled in most places. The existing drugs are no longer sufficient for the treatment of drug-resistant Mycobacterium tuberculosis due to significant toxicity and selective pressure, especially for XDR-TB. In order to accelerate the development of high-efficiency, low-toxic antituberculosis drugs, it is particularly important to use Computer Aided Drug Design (CADD) for rational drug design. Here, we systematically reviewed the specific role of molecular simulation in the discovery of new antituberculosis drugs. The purpose of this review is to overview current applications of molecular simulation methods in the discovery of antituberculosis drugs. Furthermore, the unique advantages of molecular simulation was discussed in revealing the mechanism of drug resistance. The comprehensive use of different molecular simulation methods will help reveal the mechanism of drug resistance and improve the efficiency of rational drug design. With the help of molecular simulation methods such as QM/MM method, the mechanisms of biochemical reactions catalyzed by enzymes at atomic level in Mycobacterium tuberculosis has been deeply analyzed. QSAR and virtual screening both accelerate the development of highefficiency, low-toxic potential antituberculosis drugs. Improving the accuracy of existing algorithms and developing more efficient new methods for CADD will always be a hot topic in the future. It is of great value to utilize molecular dynamics simulation to investigate complex systems that cannot be studied in experiments, especially for drug resistance of Mycobacterium tuberculosis.

Pharmacokinetics and Dosing of Levofloxacin in Children Treated for Active or Latent Multidrug-resistant Tuberculosis, Federated States of Micronesia and Republic of the Marshall Islands

BACKGROUND

In the Federated States of Micronesia and then the Republic of the Marshall Islands (RMI), levofloxacin pharmacokinetics were studied in children receiving directly observed once-daily regimens (10 mg/kg, age >5 years; 15-20 mg/kg, age ≤5 years) for either multidrug-resistant tuberculosis disease or latent infection after multidrug-resistant tuberculosis exposure, to inform future dosing strategies.

METHODS

Blood samples were collected at 0 (RMI only), 1, 2 and 6 hours (50 children, aged 6 months to 15 years) after oral levofloxacin at >6 weeks of treatment. Clinical characteristics and maximal drug concentration (Cmax) of levofloxacin, elimination half-life and area under the curve from 0 to 24 hours (AUC0-24 hours × μg/mL) were correlated to determine the optimal dosage and to examine associations. Population pharmacokinetics and target attainment were modeled. With results from the Federated States of Micronesia, dosages were increased in RMI toward the target Cmax for Mycobacterium tuberculosis, 8-12 µg/mL.

RESULTS

Cmax correlated linearly with per-weight dosage. Neither Cmax nor half-life was associated with gender, age, body mass index, concurrent medications or predose meals. At levofloxacin dosage of 15-20 mg/kg, Cmax ≥8 µg/mL was observed, and modeling corroborated a high target attainment across the ratio of the area under the free concentration versus time curve to minimum inhibitory concentration (fAUCss,0-24/MIC) values.

CONCLUSIONS

Levofloxacin dosage should be 15-20 mg/kg for Cmax ≥8 µg/mL and a high target attainment across fAUCss,0-24/MIC values in children ≥2 years of age.

Paediatric use of second-line anti-tuberculosis agents: a review

Childhood multidrug-resistant tuberculosis (MDR-TB) is an emerging global epidemic. With the imminent roll-out of rapid molecular diagnostic tests, more children are likely to be identified and require treatment. As MDR-TB is resistant to the most effective first-line drugs, clinicians will have to rely on second-line medications which are less effective and often associated with more pronounced adverse effects than first-line therapy. Despite the fact that most of these agents were discovered many years ago, robust information is lacking regarding their pharmacokinetic and pharmacodynamic properties, adverse effects and drug interactions, especially in children. Children differ from adults in the way that drugs are administered, the manner in which they are metabolised and in the adverse effects experienced. The interaction of these drugs with human immunodeficiency virus infection and antiretroviral therapy is also poorly documented. This article reviews the available second-line drugs currently used in the treatment of MDR-TB in children and discusses medication properties and adverse effects while potential interactions with antiretroviral therapy are explored.

New old challenges in tuberculosis: potentially effective nanotechnologies in drug delivery

Tuberculosis (TB) is the second most deadly infectious disease. Despite potentially curative pharmacotherapies being available for over 50 years, the length of the treatment and the pill burden can hamper patient lifestyle. Thus, low compliance and adherence to administration schedules remain the main reasons for therapeutic failure and contribute to the development of multi-drug-resistant (MDR) strains. Pediatric patients constitute a high risk population. Most of the first-line drugs are not commercially available in pediatric form. The design of novel antibiotics attempts to overcome drug resistance, to shorten the treatment course and to reduce drug interactions with antiretroviral therapies. On the other hand, the existing anti-TB drugs are still effective. Overcoming technological drawbacks of these therapeutic agents as well as improving the effectiveness of the drug by targeting the infection reservoirs remains the central aims of Pharmaceutical Technology. In this framework, nanotechnologies appear as one of the most promising approaches for the development of more effective and compliant medicines. The present review thoroughly overviews the state-of-the-art in the development of nano-based drug delivery systems for encapsulation and release of anti-TB drugs and discusses the challenges that are faced in the development of a more effective, compliant and also affordable TB pharmacotherapy.

Management of pediatric multidrug-resistant tuberculosis and latent tuberculosis infections in New York City from 1995 to 2003

BACKGROUND

Few studies have assessed the management and outcomes of multidrug-resistant tuberculosis (MDR-TB) in the pediatric population. Treatment of children with second-line TB drugs is complicated by potential toxicities of these agents.

METHODS

We performed a retrospective study of children <15 years of age treated for MDR-TB or MDR-latent TB infection (LTBI) from 1995 to 2003. We reviewed the New York City Department of Health and Mental Hygiene (DOHMH) computerized TB registry to characterize demographic characteristics, clinical presentations, treatment, and outcomes of the study subjects.

RESULTS

Twenty subjects with MDR-TB (mean age 2.7 years) and 51 with MDR-LTBI (mean age 9.8 years) were studied. The most commonly used second-line TB drugs were cycloserine, quinolone agents, and ethionamide, which were used in 70%, 69%, and 54% of subjects, respectively. Sixteen (80%) of 20 MDR-TB and 38 (75%) of 51 MDR-LTBI cases completed treatment. A greater proportion of subjects receiving care at a DOH clinic completed treatment for LTBI (36/41, 88%), when compared with subjects treated at non-DOH sites [(2/9, 22%) P < 0.001]. Review of the TB registry indicated that no subjects had recurrent disease or progression of LTBI to active disease during the study period and for 2 years thereafter.

CONCLUSIONS

Children with MDR-TB and LTBI were best cared for in public health settings. A multicenter registry for pediatric MDR-TB and MDR-LTBI would be desirable to obtain accurate rates of toxicity and cure.

[Exposure to multiresisant tuberculosis: study and follow-up of nine children]

A world increase in multidrug-resistant tuberculosis (MDR-TB) has been reported over the last few years. A larger number of diagnoses are being seen in Spain, due to the increase of immigration from high endemic TB countries. Articles published on this are anecdotal in children, and there is no clear directives for treatment of MDR-TB, or latent tuberculosis infection (ITBL) or on prophylaxis after exposure to active pulmonary MDR-TB. We present the initial management and progression of nine children after close contact exposure to an Ecuadorian woman diagnosed with active pulmonary TB, resistant to Isoniazid, Rifampicin and Pyrazinamide.

Management of multidrug-resistant tuberculosis: Update 2007

Multidrug-resistant tuberculosis (MDR-TB) with bacillary resistance to at least isoniazid and rifampicin in vitro is a worldwide phenomenon. Hot spots of the disease are found scattered in different continents. Prevention of its development through good tuberculosis control programmes operating under the directly observed therapy, short-course (DOTS) strategy is of paramount importance. However, with established MDR-TB, treatment with alternative and specific chemotherapy is necessary to achieve a beneficial outcome. Such an approach on a programme basis is currently known as the 'DOTS-Plus' strategy. Second-line (reserve) drugs utilized in the treatment of MDR-TB are generally less potent and more toxic, perhaps with the notable exceptions of some fluoroquinolones and injectable agents. Surgery has a distinct adjunctive role for the management of MDR-TB in selected patients. The emergence of extensively drug-resistant tuberculosis (XDR-TB), that is, MDR-TB with additional bacillary resistance to the fluoroquinolones and injectables, has provided a very alarming challenge to global health, as the disease currently has a low cure rate and high mortality. In order to combat XDR-TB, strengthening of DOTS and DOTS-Plus programmes is mandatory, especially in the face of surging HIV infection. Furthermore, more attention needs to be focused on developing new drugs with potent bactericidal and sterilizing activities and low side-effects, and above all, drugs that are affordable for communities worldwide.

[Multidrug-resistant tuberculosis in the pediatric age group]

AIMS

To study the clinical and epidemiological features in eight pediatric patients with multidrug-resistant tuberculosis (MDR-TB) diagnosed from 1994 to 2005 in three hospitals in Madrid (Spain).

METHODS

A retrospective study was performed in patients aged less than 15 years old with positive culture for multidrug-resistant Mycobacterium tuberculosis and patients with negative cultures diagnosed after contact with MDR-TB.

RESULTS

Pulmonary tuberculosis was diagnosed in seven patients and arthritis in one. Fifty percent of the patients were immigrants and an adult source case was found in four (50%). M. tuberculosis was isolated in gastric juice in four patients and in synovial biopsy in one. In three patients cultures were negative but these patients had previously been in contact with MDR-TB. Two strains were resistant to isoniazid and rifampicin, four were resistant to isoniazid, rifampicin and streptomycin, one was resistant to isoniazid, rifampicin, streptomycin and pyrazinamide, and one was resistant to 11 drugs. Six patients initially received conventional treatment without improvement. Patients received therapy for 15 months (range: 12 to 18) with 3 to 5 drugs according to the sensitivity study. The following adverse effects were observed: creatine phosphokinase increase (one patient), tendinitis (one patient), alteration of visual evoked responses (one patient) and transitory psychosis (one patient). One patient required pulmonary lobectomy. All patients responded satisfactorily to medical treatment.

CONCLUSIONS

MDR-TB should be suspected in patients not responding to TB treatment, especially those from countries with high resistance rates. In patients with negative cultures, treatment should rely on the results of a sensitivity study in the adult source case. MDR-TB requires the use of second-line anti-TB drugs for prolonged periods with possible toxic effects.