Drug-resistant tuberculosis and advances in the treatment of childhood tuberculosis
Seddon and Schaaf Pneumonia
Drug-resistant tuberculosis and advances in the treatment of childhood tuberculosis
James A. Seddon 0
H. Simon Schaaf
0 Centre for International Child Health, Department of Paediatrics, Imperial College London , London , UK
Over the last 10 years, interest in pediatric tuberculosis (TB) has increased dramatically, together with increased funding and research. We have a better understanding of the burden of childhood TB as well as a better idea of how to diagnose it. Our appreciation of pathophysiology is improved and with it investigators are beginning to consider pediatric TB as a heterogeneous entity, with different types and severity of disease being treated in different ways. There have been advances in how to treat both TB infection and TB disease caused by both drug-susceptible as well as drug-resistant organisms. Two completely novel drugs, bedaquiline and delamanid, have been developed, in addition to the use of older drugs that have been re-purposed. New regimens are being evaluated that have the potential to shorten treatment. Many of these drugs and regimens have first been investigated in adults with children an afterthought, but increasingly children are being considered at the outset and, in some instances studies are only conducted in children where pediatric-specific issues exist.
Tuberculosis; Children; Resistant; Treatment; Disease; Infection
How do children get tuberculosis?
If a child is exposed to an individual, usually an adult,
with infectious pulmonary tuberculosis (TB) disease they
are at risk of inhaling aerosolised Mycobacterium
tuberculosis and becoming infected. Whether they become
infected or not following exposure will depend on the
integrity of their mucosal defences, their innate immune
system, the virulence of the mycobacterium and the
infective dose. Once infection has occurred the adaptive
immune system recognises the bacilli and may clear the
organism, become overrun by it or reach an equilibrium
in which the immune system fails to eradicate the
mycobacteria but prevents them from proliferating. This final
situation is termed TB infection. In the future, the bacilli
may overcome the immune system and progress to TB
Other than occasionally having brief, viral-like
symptoms, children with TB infection usually have no clinical
symptoms or signs, and radiology shows no evidence of
TB disease. TB infection is detected through a positive
tuberculin skin test (TST) or interferon-gamma release
assay (IGRA). The risk of progressing from infection to
disease is governed by a number of factors but age and
immune status are central. From studies that examined
the natural history of TB, conducted prior to the
chemotherapy era, we know that infected infants have a 50%
risk of progression to disease, with the risk decreasing
with age through childhood but increasing again as
children enter adolescence [4, 5]. HIV-positive adults not on
antiretroviral therapy have a 7–10% risk of developing
TB each year following TB infection; [6, 7] the risk is
likely to be similar for children. Children with
malnutrition or other forms of immune deficiency have also been
shown to be more vulnerable . If children are
identified at the point that they have TB infection, the risk of
progression to disease can be markedly reduced by
giving preventive therapy.
Children with TB disease have a wide range of clinical
presentations. The most common presentation in young
children is intra- or extra-thoracic lymph node disease.
However, young children (<3 years) are also more likely
than older children or adults to develop the most severe
forms of disseminated TB, such as TB meningitis or
miliary TB. As children get older (starting from about
8 years of age) they are more likely to develop adult-type
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disease, including cavitary pathology. Due to this variety
of clinical forms, investigators are increasingly exploring
whether it is possible to divide children into those with
severe disease and non-severe disease, using consistent
definitions, with the possibility that those with
nonsevere pathology might be treated with fewer drugs and
for shorter durations (Fig. 1) .
How many children in the world have TB?
This topic is covered in detail in the article by Jenkins in
this series . Multidrug-resistant (MDR)-TB is defined
as disease caused by M. tuberculosis resistant to
rifampicin and isoniazid, whereas extensively drug-resistant
(XDR)-TB is defined as disease caused by MDR
organisms with additional resistance to a fluoroquinolone and
a second-line injectable medication. The World Health
Organization (WHO) estimates that 1 million children
developed TB in 2014 . Only 358, 521 children were
diagnosed, treated and reported to the WHO that year,
suggesting that about two thirds of the children that
develop TB each year remain undiagnosed, untreated or
were not reported. Investigators have estimated that
about 30,000 children develop MDR-TB each year [10,
12, 13]. Given that only 1000 children have been
described in the entire medical literature as having been
treated for MDR-TB at any point , under-diagnosis
and under-treatment is likely to be even worse for
Diagnosing TB infection and TB disease
Both TB infection and TB disease can be challenging to
diagnose with certainty in children . The TST and
IGRA are associated with impaired sensitivity and
specificity in children; [16–19] children can therefore be
assumed to have TB infection if they have been heavily
exposed to an infectious case of TB. If they are at high
risk of disease progression (< 5 years of age or
HIVinfected) and they have been exposed to a case of
drugsusceptible TB, then WHO recommends that they be
given preventive treatment without the need for TST or
IGRA testing . In most contexts only a small
proportion of the children (often fewer than 30%) that are
treated for TB disease have a bacteriologically confirmed
diagnosis . Treated cases are therefore confirmed or
presumed. For research purposes, investigators have
tried to quantify the confidence that is given to the
diagnosis of presumed TB and comprehensive
definitions have been developed through consensus to
describe confirmed, probable and possible TB for both
drug-susceptible (DS)  and drug-resistant (DR) TB
disease . For children presumed to have DR-TB,
multiple microbiological samples should be taken,
ideally before treatment. Once samples are taken,
however, the child should be treated with a regimen
designed on the assumption that they have the same
drug susceptibility test (DST) pattern as the identified
source case [24, 25].
Fig. 1 The continuum of tuberculosis exposure, infection, non-severe and severe disease in children and possible treatment implications
Treating drug-susceptible tuberculosis infection
What is the recommended treatment of drug-susceptible
TB infection (LTBI) in children?
Isoniazid given for 6 or 9 months has been shown to be
very effective in preventing the progression from TB
infection to disease  and a number of studies
demonstrate that 3 months of isoniazid and rifampicin is also
an effective regimen . Rifampicin alone is likely to be
effective if given for 3 or 4 months . However,
providing daily therapy to a child who is clinically well can
be challenging for many parents; adherence is frequently
poor, particularly in high burden settings [29, 30].
Are there any alternatives?
In 2011, the results of a large trial were published which
had evaluated once weekly rifapentine and high-dose
isoniazid for 3 months (12 dosing episodes) against 9
months of daily isoniazid . This demonstrated that
the shorter, once-weekly regimen was as effective in
preventing TB disease as a 9-month daily isoniazid regimen
and was also associated with better adherence. Although
the study did include children above the age of 2 years,
the investigators did not feel that there were sufficient
children in the trial to be confident of the adverse events
profile in pediatric populations. To that end, the study
continued to recruit children for a further 2 years until
more than 1000 children had been enrolled . This
found the 3-month regimen to be associated with higher
completion rates and limited toxicity. Detailed
pharmacokinetic studies and extensive modelling provide good
evidence for the best dosage to give children when using
either whole tablets or crushed tablets . This
regimen should still be evaluated in the most vulnerable age
group of less than 2 years.
Treating drug-susceptible tuberculosis disease
What is the recommended treatment of drug-susceptible
TB disease in children?
The WHO recommends that children with pulmonary
DS-TB are treated with 2 months of rifampicin, isoniazid
and pyrazinamide followed by 4 months of rifampicin
and isoniazid. They advise that ethambutol should be
added for the first 2 months in children with extensive
disease or where rates of HIV infection and/or isoniazid
resistance are high, irrespective of the child’s age .
This regimen is effective and is associated with few
adverse events;  optic neuritis is an extremely rare
adverse effect at the dosages advised . Due to emerging
pharmacokinetic evidence, the recommended dosages of
these first-line anti-TB medications were revised in 2010
as children metabolise the drugs more rapidly than
adults resulting in a lower serum concentration
following the same mg/kg dosage . It is only using the
revised dosages that young children achieve the target
serum concentrations that have been shown to be
associated with efficacy in adult studies . Following the
2010 revision of pediatric TB dosing recommendations,
the ratio of individual medications included in the fixed
dose combination (FDC) tablets similarly required
updating. A new appropriately dosed, scored, dispersible
and palatable pediatric FDC tablet was launched in
December 2015; these tablets are expected to be available
for use by the end of 2016 .
Is it possible to shorten TB treatment?
Six months is a long time to treat a child and a number
of adult studies have recently been completed that aimed
to shorten treatment to 4 months using alternative
regimens. In the RIFAQUIN trial adults were randomised to
one of three regimens: (i) the traditional 6-month
WHO-recommended regimen; (ii) 2 months of daily
ethambutol, moxifloxacin, rifampicin and pyrazinamide
followed by 2 months of twice weekly moxifloxacin and
rifapentine; and (iii) 2 months of daily ethambutol,
moxifloxacin, rifampicin and pyrazinamide followed by 4
months of once weekly moxifloxacin and rifapentine
. Although the 4-month regimen was inferior to the
standard course of treatment (more patients relapsed),
the alternative 6-month regimen, in which patients only
had to take treatment once a week in the continuation
phase, was non-inferior. This raises the exciting prospect
of once weekly treatment for children in the
continuation phase of treatment. The OFLOTUB trial compared
the standard 6-month regimen with a new experimental
regimen in adults, in this case gatifloxacin, rifampicin
and isoniazid for 4 months with additional pyrazinamide
for the first 2 months . As with the RIFAQUIN trial,
the shortened regimen was found to be inferior with
more unfavourable outcomes (death, treatment failure,
recurrence) in the shorter treatment group. However,
there was great variation by country and also by HIV
status and body mass index (outcomes were similar
between the two treatments for malnourished patients and
those with HIV). This suggests that there may be a role
for shortened treatment in some patient populations or
it might work in certain health systems. The final adult
study, the REMox trial, compared the WHO adult
firstline regimen to two experimental arms: (i) 4 months of
moxifloxacin, isoniazid and rifampicin with additional
pyrazinamide for the first 2 months; and (ii) 4 months of
moxifloxacin and rifampicin with ethambutol and
pyrazinamide for the first 2 months. More rapid
cultureconversion was seen in the moxifloxacin-containing
arms but the shortened regimens were inferior to the
WHO regimen .
A pediatric trial, SHINE, is due to soon start at a
number of sites in Africa, and also in India, that will evaluate
whether children with non-severe disease can be treated
successfully with only 4 months of treatment . If
more effective contact tracing occurs following the
diagnosis of TB in adults, it is expected that more children
with TB will be detected at an earlier stage in their
disease process. If these children can be safely treated
with shorter treatment regimens, better adherence and
cheaper treatments would be expected.
What is the best treatment for TB meningitis?
The WHO suggests that children with TB meningitis
(TBM) should be treated for 2 months with isoniazid,
rifampicin, pyrazinamide and ethambutol followed by 10
months with isoniazid and rifampicin at the standard
dosages . There are concerns that this regimen may
not be ideal. Isoniazid and pyrazinamide penetrate well
into the cerebrospinal fluid (CSF), rifampicin penetrates
moderately when there is meningeal inflammation and
poorly after this has subsided, with ethambutol having
almost no penetration [43–45]. Therefore, during the
first 2 months of treatment two drugs are being given
with good CSF penetration and for the subsequent 10
months effectively only one drug is being given. In areas
of increased rates of isoniazid resistance, many children
are left without any effective treatment after the first 2
months. Further, the dosages recommended for
treatment do not fully consider the penetration into the CSF
and it is expected that higher dosages are required to
achieve adequate CSF concentrations. Outcomes for
children with TBM are very poor . One group in
Cape Town, South Africa, have been treating TBM in
children with a short, intensive regimen for a number of
years [47–49]. This consists of high-dose isoniazid
(1520 mg/kg), rifampicin (20 mg/kg), pyrazinamide (40 mg/
kg) and ethionamide (20 mg/kg) for 6 months.
Outcomes are reasonable and the regimen is well tolerated.
Although an exciting trial in adults with TBM in
Indonesia showed that high dosages of rifampicin (given
intravenously) combined with moxifloxacin improved
outcome , a further study in Vietnam failed to
demonstrate a protective effect of higher dose rifampicin
and the addition of levofloxacin. A pediatric trial,
TBMKIDS, has started in Malawi and India and aims to
evaluate the pharmacokinetics, safety and efficacy of
levofloxacin and high-dose rifampicin in TBM .
The role of immune modulators in pediatric TBM is
still unclear. A number of trials have demonstrated that
the use of steroids offers a modest benefit on death and
severe disability . However, this may be restricted to
only those with certain host genotypes  and the
dosage to give children remains unclear . A trial of
high-dose thalidomide as an immune modulator in TBM
was stopped early due to worse outcomes in the
intervention group . However, thalidomide at a lower
dose has since been used successfully in the treatment of
optochiasmatic arachnoiditis and
tuberculomas/pseudoabscesses in children [56, 57]. The effect of aspirin is
unclear. In one pediatric trial aspirin demonstrated a
benefit , whereas in another it did not .
Treating drug-resistant tuberculosis infection
How does drug-resistant TB develop?
Drug resistance can be acquired through sequential,
selective pressure in the face of inadequate therapy. Here,
spontaneously occurring mutants are favoured that
provide resistance against individual drugs. This process
usually takes place in the presence of a high bacillary
load, where previously drug-susceptible organisms
develop resistance within one human host. Alternatively,
resistance can be transmitted where mycobacteria, already
resistant, are transmitted to a new host. Additionally, a
combination of the two can occur when one individual
receives a mycobacterium already resistant to one or more
medications and then in the face of inadequate treatment
develops resistance to further antibiotics (resistance
amplification). Children usually have transmitted
resistance, as disease is normally paucibacillary, making
acquired resistance less likely.
How should we investigate a child who has been exposed
to a drug-resistant TB source case?
If a child has been exposed to an infectious source case
with DR-TB they should be assessed for evidence of TB
disease. This would include a comprehensive symptom
screen, clinical examination and, where available, chest
radiography. Any concerns that the child has TB disease
should necessitate further investigation. If the child is
symptom-free, growing well, with no concerning clinical
signs, they should be evaluated for risk of infection.
Where available, TST and/or IGRA could be employed
to evaluate the risk of infection but if they are
unavailable an assessment can be made on the basis of
How should we treat a healthy child who has been
exposed to a drug-resistant TB source case?
Children exposed to either rifampicin mono-resistant
TB or isoniazid mono-resistant TB can usually be given
either isoniazid or rifampicin alone, respectively. The
correct management of children exposed to MDR-TB is
unclear , with a limited evidence base to support
policy [61, 62]. Using isoniazid and/or rifampicin (the
two drugs for which there is a strong evidence base for
preventive therapy) is unlikely to be effective  as the
organism is, by definition, resistant to these drugs.
International guidelines are highly variable . The British
National Institute for Health and Care Excellence advises
follow up with no medical treatment , as does the
WHO . The US Centers for Disease Control and
Prevention (CDC), the American Thoracic Society and
the Infectious Diseases Society of America advise giving
two drugs to which the source case’s strain is susceptible
. The European Centre for Disease Prevention and
Control suggest that either treatment or close follow up
are legitimate options .
Only a few studies have assessed preventive therapy in
MDR-TB child contacts. In Israel, 476 adult and child
contacts of 78 pulmonary MDR-TB patients were
evaluated. Twelve were given a tailored preventive therapy
regimen, 71 were given isoniazid, six were given other
treatments and 387 were not given any treatment. No
contacts developed TB . In Cape Town, from 1994
to 2000, 105 child contacts of 73 MDR-TB source cases
were identified and followed up. Two (5%) of the 41
children who received tailored preventive therapy
developed TB as opposed to 13 (20%) of the 64 children who
were not given any . In a retrospective study in
Brazil, 218 contacts of 64 MDR-TB source cases were
given isoniazid, while the remainder were observed
without treatment. The rate of TB was similar in the group
who were given isoniazid (1.2 per 1000-person-months
of contact) compared to those who were not (1.7 per
1000-person-months of contact; p = 0.47). In two
outbreaks in Chuuk, Federated States of Micronesia, five
MDR-TB source cases were identified. Of 232 contacts
identified, 119 were offered preventive therapy, of which
104 initiated a fluoroquinolone-based regimen. None of
those who started preventive therapy developed TB
disease, whereas three of the 15 who did not take treatment
did [68, 71]. A prospective study from Cape Town
recruited 186 children during 2010 and 2011 who had
been exposed to adult source cases with MDR-TB. All
were offered three-drug preventive therapy with
ofloxacin, ethambutol and high dose isoniazid. Six children
developed TB and one infant died. Factors associated with
poor outcome were: age less than 12 months, HIV
infection and poor adherence . Although a clinical trial is
urgently needed to assess how to best manage children
exposed to MDR-TB, these studies together suggest that
providing preventive therapy may be effective in
stopping the transition from infection to disease. Three
randomised trials are planned. VQUIN are recruiting adult
contacts of MDR-TB in Vietnam and randomising them
to either levofloxacin or placebo. TB-CHAMP will take
place in four sites in South Africa and recruit children
under 5 years of age following MDR-TB household
exposure. This trial will also randomise contacts to
levofloxacin or placebo. PHOENIx will take place at a
number of sites globally and recruit adults and
children with all patients randomised to either delamanid
or isoniazid. Although the results of these trials are
eagerly awaited, an expert group, convened in Dubai
in 2015, concluded that there is currently enough
observational evidence to treat high risk contacts with
a fluoroquinolone-based regimen .
How should we follow up these children?
As 90% of children who develop TB disease do so within
12 months and as almost all do so within 2 years ,
follow up for at least 12 months is advisable whether
preventive therapy is given or not. The WHO and
several other guidelines recommend 2 years of follow up.
Clinical follow-up is likely sufficient but where
resources permit, chest radiology at 3–6-month
intervals can detect early disease when symptoms may not
Treating drug-resistant tuberculosis disease
How do you design a regimen for a child in order to treat
for drug-resistant TB?
In 2016 the WHO updated its recommendations for the
management of MDR-TB . It also re-structured the
groupings into which the different drugs were placed
(Table 1). Drugs are added to the regimen in the
following order (as long as the drug is likely to be effective):
first a fluoroquinolone is added (WHO Group A),
followed by a second-line injectable medication (Group
B). Further drugs from Group C are added until four
likely effective drugs are present. To strengthen the
regimen or to provide additional drugs to make four
effective drugs, agents from Group D can be added (Fig. 2).
Although for adults it is recommended that the
intensive phase (including the injectable agent) should last
8 months and the full duration of therapy should be no
less than 20 months, the 2016 WHO guidelines
recognise the fact that many children with non-severe disease
have been successfully treated with shorter regimens and
many with no injectable in the regimen. Given the high
rates of irreversible hearing loss, consideration should be
given to either omitting the injectable agent or giving it
for a shorter period of time (3–4 months) in children
with non-severe disease. Total duration of therapy could
also be shorter (12–15 months) than for adults.
How should children being treated for drug-resistant TB
be followed up and monitored?
Children should be monitored for three reasons: to
determine response to therapy; to identify adverse events
early; and to promote adherence. A suggested
monitoring schedule, which should be adapted to local
conditions and resources, is demonstrated in Table 2.
Response to therapy includes clinical, microbiological
and radiological monitoring. Children should be
clinically assessed on a regular basis to identify symptoms or
signs that might signal response: activity levels,
respiratory function and neurological development. Height and
weight should be measured monthly and, for children
B Second-line injectable agents
D Add-on agents
D3 p-aminosalicylic acid
Abbreviation Important Adverse Events
Lfx Sleep disturbance, GI disturbance, arthritis, peripheral neuropathy,
As levofloxacin with QTc prolongation
As levofloxacin with QTc prolongation
Diarrhoea, headache, nausea, myelosuppression, neurotoxicity,
optic neuritis, lactic acidosis and pancreatitis
Skin discoloration, abdominal pain, QTc prolongation
Hepatitis, peripheral neuropathy
Headache, nausea, liver dysfunction, QTc prolongation
Nausea, vomiting, dizziness, paresthesia, anxiety,
GI intolerance, hypothyroidism, hepatitis
GI intolerance, hypersensitivity reactions, seizures,
liver and renal dysfunction
Table 1 New drug groupings published by the World Health Organization in 2016 
C Other core second-line agents
Gastrointestinal disturbance, metallic taste, hypothyroidism
Neurological and psychological effects
with pulmonary disease, respiratory samples for smear
microscopy and culture (not genotypic evaluation during
follow-up) should be collected where possible. Children
with pulmonary disease should have a chest radiograph
at 3 and 6 months and at any time if clinically indicated.
It is also useful to have a chest radiograph at the end of
therapy to provide a baseline for follow-up.
Children should be assessed clinically for adverse
events on a regular basis. Prior to the start of treatment,
children should have a baseline assessment of thyroid
function, renal function and have audiological and vision
examinations. Both ethionamide and para-aminosalicylic
acid (PAS) have been shown to cause hypothyroidism
[76–81] and the thyroid function should be checked
every 2 months. The injectable drugs can cause renal
impairment and hearing loss [82–85]. Renal function
should be determined every 2 months; hearing
evaluation should be done at least every month while on an
injectable drug and 6 months after stopping the agent,
as hearing loss can continue after discontinuing the
drug. The testing of hearing is age-dependent and for
those older than five with normal neuro-development,
pure tone audiometry (PTA) is the best assessment.
Otoacoustic emissions can be used to test the hearing in
younger children but visual testing is challenging for this
age group. Children being given ethambutol who are
able to co-operate with colour vision testing, should be
assessed monthly, using an appropriate Ishihara chart.
This is usually possible from the age of five. Clinicians
should, however, be reassured that the incidence of
ocular toxicity is very rare when ethambutol is given at the
recommended dosage .
What are the common adverse effects associated with
treating children for drug-resistant TB?
Most anti-TB drugs can cause gastrointestinal upset and
rash but in most instances, these resolve without
treatment and without compromising therapy. Severe
cutaneous drug reactions, such as Stevens-Johnson syndrome,
necessitate immediate cessation of all drugs until the
symptoms have resolved. Gastrointestinal upset is most
pronounced with ethionamide and PAS and frequently
this can be managed without stopping the drug by dose
escalation, by dividing the dose or by anti-emetics in
older children/adolescents. If either colour vision or
hearing are found to be deteriorating, consideration
should be given to stopping the ethambutol (vision) or
injectable medication (hearing); if not a failing regimen,
substitution with another drug could be considered. If
the thyroid stimulating hormone (TSH) is elevated and
the free T4 is low then consideration should be given to
starting thyroxine substitution. Peripheral neuropathy
Fig. 2 Constructing a regimen for the treatment of a child with multidrug-resistant tuberculosis
can be treated by either increasing the dose of
pyridoxine or reducing the dose of isoniazid or linezolid. If it
persists, the causative drug should be stopped.
Determining the cause of neuropsychiatric adverse
events can be complicated as many drugs can cause
dysfunction. Dose reduction may help, but if
symptoms persist the likely drug should be stopped. Joint
problems can be caused by pyrazinamide and the
fluoroquinolones and management options include
reducing or stopping one/both of these drugs.
Hepatotoxicity usually starts with new-onset vomiting.
Clinical hepatitis (tender liver, visible jaundice)
necessitates immediate cessation of all hepatotoxic
drugs. These include rifampicin, isoniazid,
pyrazinamide, ethionamide, PAS, beta-lactams and
macrolides. Treatment should continue with the remaining
drugs and consideration given to starting any other
available medications that are not hepatotoxic. The
hepatotoxic drugs can be re-introduced if felt to be
necessary, one-by-one every 2 days, while checking
the liver enzymes to identify the possible causative
How successful is treatment for drug-resistant TB in
A systematic review and meta-analysis, published in
2012, identified only eight studies reporting the
treatment of MDR-TB in children; 315 children were
included in the meta-analysis . Successful outcomes
were seen in 82% of children, as compared to 62% in
adults [88, 89]. It is difficult to draw too many firm
conclusions from such small numbers but it does
appear that if children are identified, diagnosed and
treated with appropriate therapy, outcomes are very
good. However, these individualised approaches
require high levels of expertise from the clinicians who
manage these children, the treatment is long (up to
18 months and longer) and is associated with
significant adverse events.
Since this systematic review there have been a large
number of publications that have described the
treatment of MDR-TB in children [90–108]. In one study
from Cape Town, Western Cape children were
classified as having had severe or non-severe disease .
The children with non-severe disease were younger,
Table 2 Suggested schedule of follow up for children on treatment for multidrug-resistant tuberculosis
Toxicity (symptoms, signs)
Colour vision testingb
TB culture and DSTd
Creatinine and potassiuma
CD4 count and viral load
DST drug susceptibility test, TSH thyroid stimulating hormone, ECG electrocardiogram, LFTs liver function tests
aMonthly whilst on an injectable and at 6 months following termination of injectable
cbIIff aonnyepthualmmobnuatroyl ionrvloi nlveezmoleidnt or at any point if clinically indicated; to be repeated at the end of treatment
dMonthly if old enough to expectorate. If unable to expectorate and initially smear or culture positive, monthly until culture-converted then 3 monthly. If initially
smear and culture negative, to perform if clinically indicated
feiiff oonn leinthezioonliadmoirdeif, HpIrVo-tphoiosintiavmeide or PAS
gif on bedaquiline or delamanid
better nourished, less likely to have HIV infection,
were less likely to have confirmed disease and less
likely to have sputum smear-positive TB. They were
more commonly treated as outpatients, less likely to
receive an injectable medication and were given
shorter total durations of medication (median
12 months vs. 18 months in the severe cases). A
study from four provinces in South Africa (outside
the Western Cape) collected routine data on the
treatment of more than 600 children with MDR-TB.
Although mortality was slightly higher than in other
studies at 20%, these children were often treated
outside of specialist centres. In preparation for the
revision to the WHO DR-TB guidelines an individual
patient systematic review and meta-analysis was
commissioned to evaluate the treatment of children
with MDR-TB. More than a thousand children were
included and treatment outcomes were successful in
77% of cases .
In addition to these studies, there have been a number
of pharmacokinetic investigations of second-line anti-TB
drugs in children [109–111] and novel delivery systems
have been designed . A consensus statement has
been developed suggesting definitions that could be used
in pediatric MDR-TB research  and a number of
guidelines have been published [113–116], as well as a
practical field guide .
Are there any new drugs to treat children for
A couple of antibiotics traditionally used for the
treatment of other infections are now more commonly used
[118–122] and have been promoted in the WHO drug
grouping. Linezolid was shown to be highly effective in
adult patients with XDR-TB who were failing therapy
. Almost all the adults developed adverse effects,
some severe, necessitating cessation of therapy. A
systematic review demonstrated that linezolid could be an
effective component of DR-TB treatment regimens but
is associated with significant adverse events .
Linezolid in children seems as effective as in adults, but with
fewer adverse events [95, 125–127]. Clofazimine,
traditionally an anti-leprosy drug, has also gained a great
deal of interest recently mainly due to its central role in
the Bangladesh regimen (discussed later) . A
systematic review of clofazimine use in DR-TB suggested
that it should be considered as an additional drug in
DR-TB treatment . Although few children have
been described as treated for TB using clofazimine, there
is good experience of using the drug in children with
leprosy. Apart from reversible skin discoloration and
gastrointestinal disturbance, it appears to be
Two new drugs have been licenced and given
conditional approval by WHO: bedaquiline and delamanid.
Bedaquiline is a diarylquinoline that acts by inhibiting
intracellular ATP synthase. It has a very long half-life
and is effective against actively replicating as well as
dormant bacilli. In clinical trials it has been shown to
reduce the time to culture conversion in adults with
pulmonary TB, as well as increasing the proportion that
do culture-convert.  Although it has not been
licenced for use in children, bioequivalence studies of two
pediatric formulations (granules and water-dispersible
tablets) have been conducted  and pharmacokinetic
and safety studies are planned. The CDC advises that on
a case-by-case basis bedaquiline might be considered in
children when ‘an effective treatment regimen cannot
otherwise be provided’ . Delamanid is a
nitroimidazole (like metronidazole) and acts predominantly on
mycolic acid synthesis to stop cell wall production. It
has been shown to increase culture conversion and also
improve outcome in adult studies [134, 135]. Pediatric
formulations have been developed and pharmacokinetic
and safety studies are underway in children . A
single case report describes the use of delamanid in a
12year-old boy who was failing treatment and was infected
with a highly resistant organism . The Sentinel
Project of Pediatric Drug-Resistant Tuberculosis has
produced clinical guidance to assist in the use of these new
agents . They suggest that both drugs could be
considered in children older than 12 years and, in certain
circumstances, in children younger than this. It is also
suggested that consideration be given to using
delamanid in place of the injectable drug in pediatric regimens;
this would need careful follow-up and documentation of
efficacy and safety.
Are there any new regimens to treat children for
In 2010, a seminal article was published describing an
observational study conducted in Bangladesh .
Sequential cohorts of patients (mainly but not all adults)
with MDR-TB were given different treatment regimens,
each differing from the previous by the substitution or
addition of one drug. The final cohort were given a
9month regimen, consisting of kanamycin, clofazimine,
gatifloxacin, ethambutol, high-dose isoniazid,
pyrazinamide and prothionamide for 4 months, followed by
gatifloxacin, ethambutol, pyrazinamide and clofazimine for
5 months. Of these patients, 88% had a favourable
outcome (cured or treatment completed), compared to
poorer outcomes for the five previous cohorts who had
been given longer regimens (typically 15 months) with
drugs including an earlier generation fluoroquinolone
(ofloxacin) and without clofazimine. This study has
generated much interest and has led to a number of trials
and observational cohorts which seek to further evaluate
this 9–12 month regimen [139, 140]. The STREAM trial
is a randomised, non-inferiority trial that compares a
similar 9-month regimen to the standard
WHOrecommended regimen. It should complete by the end
of 2016 . Although all of the individual drugs with
the ‘Bangladesh regimen’ are available for children in
some form and are used either to treat TB already or are
used for other indications, children have not been
included in STREAM. The 2016 WHO guidance has
suggested that children could be considered for treatment
with the 9–12 month regimen under the same conditions
as adults, namely when confirmed or suspected of having
MDR-TB and where resistance to the fluoroquinolones is
not suspected. A single case report describes the
treatment of an adolescent treated with this regimen .
There is currently unprecedented interest in pediatric
TB with new drugs, new regimens and new approaches
to the treatment of infection and disease for both
DRand DS-TB. We have a better understanding of the
burden of childhood TB and better diagnostic tests.
However, only a third of the children that develop TB are
diagnosed, treated and notified. Children are still dying
of this disease and TBM results in significant mortality
and morbidity even if treated. Treatments for both TB
infection and disease are long and the evidence base for
the treatment of DR-TB is poor. We still have a long
way to go and pediatric TB research still lags a long way
behind research into adult TB.
New, shorter regimens are still required for the
treatment of both infection and disease and for both DS- and
DR-TB. Less toxic regimens are needed for the
treatment of DR-TB disease and a better evidence base is
needed for the treatment of DR-TB infection.
Childfriendly formulations for all TB drugs are needed and
our understanding of the pharmacokinetics of the
second-line drugs needs further work. Although we have
come a long way, there is still a long way to go.
CDC: Centers for Disease Control and Prevention; CSF: Cerebrospinal fluid;
DR: Drug-resistant; DS: Drug-susceptible; DST: Drug susceptibility test;
FDC: Fixed dose combination; HIV: Human immunodeficiency virus;
IGRA: Interferon-gamma release assay; LTBI: Latent tuberculosis infection;
MDR: Multidrug-resistant; PAS: Para-aminosalicylic acid; PTA: Pure tone
audiometry; TB: Tuberculosis; TBM: Tuberculous meningitis; TSH: Thyroid
stimulating hormone; TST: Tuberculin skin test; WHO: World Health
Organization; XDR: Extensively drug-resistant
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