31 Diagnosis of Childhood Tuberculosis Session 02

31 Diagnosis of Childhood Tuberculosis Session 02


.
So, we understood the algorithm it is equally important for us to understand the specimens
for diagnosis, why is it important? In an adult it is easy to combine because they can
voluntarily give you sputum, children cannot. One, they may not produce sputum at all; 2
even if they do produce sputum they are not able to expectorate at will.
And young children cannot even be told to expectorate or throw ups sputum out, they
tend to swallow it. And that makes the specimen learning about specimen in childhood TB more
important . So, as I said you could have a spontaneously coughed up sputum which is good
to combine an older child say above 7, 8 or 9 years of age or you could have a child at
any age; who is just having dry cough you could induce his sputum and we learn about
it how we do it. Or you could have a situation where child is just not bringing up that sputum
and you could use alternatively gastric aspirate. I will explain to you why gastric aspirate
is important and rarely like I said for persistent pneumonias, where you refer this child to
an expert you may have to record to bronchoscopic lavage; this is not what we use routinely
. For sputum you need 2 sub specimen; if it
is for smear and if it is CBNAAT; a single specimen is needed generally children up to
8 to 10 years can bring up sputum . What is gastric aspirate? Gastric aspirate
is a technique which is used to collect gastric contents to confirm TB diagnosis, as children
often are unable to expectorate sputum and they tend to swallow it. Once they swallowed
it; that swallowed sputum which may contain M. tb can be retrieved from the stomach content
because it stays there for right, but it will stay there if only this child remains fasting.
That means, a gastric aspiration is always performed after some period of fasting which
we say it is about 4 hour to 6 hours in an older child. And you in an infant perhaps
you will not be able to keep them fasting longer than 3 hours and; it is performed on
2 consecutive mornings if you are looking at smear and a single if you have CBNAAT available
. Induced sputum is an alternative therapy which
is alternative method of collecting ah the specimen which is there. Sputum production
can often be induced by giving 3 to 5 percent hypertonic saline. So, you nebulize 3 to 5
percent hypertonic saline and child expectorates that sputum there after once it is induced.
Since hypertonic saline sometimes can cause wheeze it is important that we premedicate
this child with nebulized salbutamol. So, you first give a course of salbutamol,
followed by 3 to 5 percent hypertonic saline. So, you give one dose and thereafter you give
3 to 5 percent hypertonic saline to the patient. This older child after inducing sputum may
be able to provide this specimen at ah you know by you you give light percussion after
inducing sputum and ask the child to expectorant they are able to throw up.
But in a younger child who does not understand these instructions, this will be again swallowed
and what you can do is in that situation we can attach a mucus trap to wall suction and
put that through the nose into the nasal pharynx; when it tickles in nasal pharynx the child
it will provoke cough and that induced sputum which has been loosened by percussion by use
chest percussion would come up. And because of the suction it will be trapped
into the mucus trap before the child is able to swallow it and that is a nasopharyngeal
collection of the deep respiratory sputum which has been induced by giving hypertonic
saline and that is why it is called induced sputum .
So, these are important ways we can we can collect ah the sputum what is important ah
to remember is sputum induction is an aerosol generating procedure in a potentially infected
child . And therefore, for the safety of the health
worker it is important that adequate infection control precautions are ensured; some the
the there should be a negative pressure, there there should be a N 95 mask which is used.
So, that the there is enough safety for the health worker in there . What is also important
is that if this child is having severe respiratory distress or has a low level of consciousness
or has is intubated or is bleeding or in his current wheezing, then inducing sputum may
not be a good idea because their their distress may increase. So, with these caveats it is
possible to use induced sputum in younger children who are not able to expectorate or
give you sputum directly . Now, once you have collected this sputum;
the other difficulty we always had in children was that because it is a paucibacillary disease;
it is a primary disease this smear positivity was very poor. Smear positive range about
10 to 15 percent in in pediatric TB which in younger children; in older adolescent it
may be about 40 percent. So, as a thumb rule the whenever you have
a paucibacillary disease the the yield is less, but this is increased tremendously by
use of CBNAAT. And these are many studies which have shown that a CBNAAT can pick almost
as two third or as much as a culture a from from respiratory specimen and there are enough
to do that . But having said that it is very important to tell here at this point of time
the culture positivity in pediatric TB is not more than 50 percent .
So, understand this very clearly overall yield in the respiratory specimen is less than culture
or equal to culture with gene xpert , but which is about 50 percent overall which means
a negative CBNAAT does not rule out TB. So, it is a good ruling test, but it is not a
very good rule of test that is something important to remember. Because ah are you know looking
up for for a test which is very effective in children still continues despite the improvement
provided by CBNAAT . Let me now change that and talk about the
third test which I introduced to you in the algorithm and that is the tuberculin skin
test or mantoux . Now tuberculin skin test again what strength you use? If you will read
the western textbook most textbooks say for 5 TU; , but what is important to remember
is they say 5 TU of PPD-S. PPD-S is not something which is available
in our country; what is available to us is PPD RT 23; an equal dose of PPD RT 23; to
a 5 TU of PPD-S is 2 TU . So, therefore, what you need is 2 to tuberculin unit of PPD RT
23 forgiving this test that is something very important to remember because 5 TU PPD RT
23 is much higher dose right . So, having know that you give it I will just show you
the method of giving PPD remember; what you read it is you read the induration and a positive
test which is considered positive when it is more than 10 millimeter just indicates
TB infection it does not indicate a presence of TB disease. This is how you give ah TT
ah PPD test or to between skin test also called as a mantouxs test .
You would need to give it intra dermal making an angle of about 50 percent or in the skin
and you are able to raise a wheel of about 6 millimeter ok. Once you have raised that
wheel you you take out this this 26 gauge needle and this child comes back to you after
48 to 72 hours and you read the induration and not the rhythma; that means, you do heat
the hardness of skin; which can be sometimes as raised and as dramatic as this , but in
malnourished children can be better felt than seen. So, induration is what you measure in
children after giving tuberculin and a positive test is 10 millimeter .
You could have several situations where you could have a false negative tuberculin skin
test even in an infected child. One of the commonest reason being incorrect administration
or could be an improper storage of tuberculin or it could be because of any immune deficiency
which could be either HIV or a primary immunodeficiencies or use of immunosuppressive drugs or are severe
malnutrition. Severe disease bacterial viral or micro bacterial
can also give rise to false negative tuberculin skin disease; this ah tuberculin skin test
. You could have a false positive test one because of incorrect interpretation; if we
read arrhythmia which may sometimes be more than the induration or because of the infection
by the non tuberculosis mycobacteria . This is how; what we what are the tests which
are used for pulmonary TB . Now, quickly let me take you through with the other tests which
are specific or specific investigations for diagnosis of extra pulmonary TB . So, for
extra pulmonary TB like peripheral lymphadenopathy; tubercular lymph adenopathy what you need
is a fine needle aspiration psychology which is seen by a pathologist or you could do a
lymph node biopsy, if your psychopathology does not give you the answer .
However a very important test which can be done on this aspirate is either a smear or
CBNAAT and as I all as I said in the past also CBNAAT gives you much better sensitivity.
So, remember if you aspirate pass or cell sap from or lymph node; this is a very good
material which can be used for a microbiological diagnosis also . So, if you are in a smaller
place where a trained histopathology just may not be available, a cytopathologist may
not be available you can still do aspiration and send that for microbiological diagnosis
which cause a very good yield for peripheral lymphadenopathy .
Miliary TB again we because it rest of the thing it are just like pulmonary TB, but because
it is miliary it spread, disseminated all over body you may like to do a CSF to pick
up in early meningitis. Pleural effusion is something else which which was was comes in
in TB as a manifestation of TB in children .
This is where you would need to do a pleural tap to differentiate from other causes of
global effusion in children which can be bacterial not always micro bacterial. And what helps
you here is the biochemical tests that it is an exudates, which is more than 3 gram
proteins and it has usually lymphocytic cells and it is usually not pus cultures may help.
However, CBNAAT is something which is very poor yield for pleural TB for abdominal TB
abdominal ultrasound, ascitic tap may be useful when there is ; for osteoarticular again appropriate
biological specimen like joint tap synovial biopsy may be used. For pericardial again
you could do you do a pericardial tap and you pick them up by bioradio measure .
So, for algorithm when it comes to accept pulmonary TB, it is about collecting an appropriate
specimen from the site which may not always be available, but if it is available; you
subject that to microbiology through CBNAAT or liquid culture depending on this what is
available to you one any one of these 2. It would either detect an MTB or not if it
detects it gives you a confirmed diagnosis which will be in a relatively small proportion.
A larger proportion 50 to 60 percent sometimes even higher would be where you would not be
able to detect MTB; in those gateway situations it does not rule out TB if you still have
a high clinical ah suspicion. You do other diagnostic tools as I said I I referred to
some of them in the previous ; slide and and then make a clinically diagnosed EPTB.
And remember imaging like neuroimaging for TBM ah looking at the biochemistry and cytology
for effusions may be supportive or the other ah diagnostic tools which may help you to
make a diagnosis of EPTB or they may confirm an alternative diagnoses .
The index TB guidelines from our country they they I have they have made very strong recommendations
about usage of these tests based on the currently available evidence. For lymph node TB they
they strongly recommend using expert TB as an additional test; in addition to FNAC or
if FNAC not available; this can be used as a sole test. For meningeal again expert TB
can be an adjunctive test; however, here CSF and neuroimaging play a very important role.
Because it is a very serious illness you need an early diagnosis and CBNAAT may not come
positive in about 60 pursuant of case equation therefore, you would use this as an adjunctive
test and not the sole test. But it is an important test to do anyway because you will get a confirmation
in about 45; 40, 50 percent cases. Pleural TB is where expert TB does not help you; CBNAAT
does not help you that is where you would need alternative diagnosis ah methods.
One of the methods recommended is ADA or adenosine deaminase levels; however, these are not a
good distinct for pediatric cases; they may be good distinct are in adults where your
differential is a malignancy, but in children usually the differential diagnosis for a pleural
effusion is other infections, which are not very clearly delineated by ADA and therefore,
it is not recommended for pediatric meningeal TB .
So, far we talked about drug sensitive TB, but we need to quickly also remember about
when to suspect drug resistant TB where you would need a bigger effort to get a microbiological
diagnosis . The drug resistance TB should be suspected
when the contact; there is a known contact with a presumptive or a known or confirmed
case of drug resistant TB by with in this patient. Or if this child is not responding
to the first line therapy if there is a failure to therapy or this child shows an initial
improvement, but then starts deteriorating clinically as well as radiological he becomes
a suspect or DRTB suspect . So, remember somebody who has been exposed
to a case with MDR TB or likely MDR TB or patient who does not respond to first line
therapy or a patient who shows initial or a partial response and then then deteriorates;
are these situations where you should keep a possibility of DRTB as a strong alternative.
And this is where you would start looking for a microbiological verification or presence
of of drug resistance . The other comorbidity which should be identified
and talked of is HIV TB in children. HIV test is indicated and that is the national policy
in all children with suspected and confirmed TB ok .
Children living with HIV have a higher risk of having TB infection and have higher risk
of progressing from infection to TB disease. And therefore, have a higher TB related morbidity
and ah and mortality and therefore, one must look at TB as a comorbidity in children who
have HIV disease; Approach to ah diagnosis of TB remains quite similar to the; what what
I showed to you earlier . So, what are the key messages at the end of
my talk? I would say diagnosis of TB in children is challenging because microbiological diagnosis
is not possible in all; where even it is possible the excess to specimen is difficult. While
you need ah a early diagnosis because there can be serious involvement like CNS involvement
or meningitis. We should always make an effort for microbiological confirmation even in pediatric
TB; though you yield is lesser than adults. Xpert MTB or gene expert or CBNAAT has significally
improved the prospect of TB diagnosis in children. And therefore, this should be used as early
as possible depending on the facilities available to you , but this should be guided to you
by presence of a lesion. So, when you have a presumptive case who has an X-ray suggestive;
highly suggestive or an X-ray which was not highly suggestive, but has no response to
antibiotic, in all this situation when you collect a respiratory specimen you should
use CBNAAT as an important test for making diagnosis in children .
However, remember CBNAAT will not always be possible and you would have to make a diagnosis
in the absence of bacteriological confirmation using other techniques like X-ray ultrasound
CT and MRI which may be useful depending on the type of environment. Thank you so, much
for your kind attention I hope you you; I was able to describe the diagnosis of childhood
TB to you well. Thank you.

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