R Dayal, P Senthilkumar, VM Katoch,
DS Chauhan and NK Yadav,
Department of Pediatrics, SN Medical College, Agra and
National JALMA Institute for Leprosy
and Other Mycobacterial Diseases (ICMR), Agra, UP, India.
Email: [email protected]
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The absolute diagnosis of
tuberculosis in
children is often difficult and challenging
because combination of a typical clinical
picture with demonstration of Mycobacterium tuberculosis from the
secretions and tissues is not possible in majority of children, who have a
paucibacillary disease. Real-time PCR methods, based on hybridization of
amplified nucleic acids with fluorescent-labelled probes, as evaluated in
adults, has shown sensitivity of 71 to 98% and specificity close to
100%(1-3). We conducted this study to compare the diagnostic value of real
time technique with conventional PCR technique (IS6110), culture (Bac
T/Alert), and biochemical and cytological studies in CSF, for diagnosis of
neurotuberculosis in children.
We enrolled 47 children (0-18 years) with
neurotuberculosis, between March 2008 to October 2009. Another 8 patients
with non tuberculous involvement of the same system were taken as matching
disease controls. Inclusion and exclusion criteria were as per IAP
guidelines(4). A written informed consent was taken from patients’
attendants before the commencement of the study.
After a detailed clinical history and a thorough
clinical examination, a complete blood count, tuberculin test, chest
radiograph and CSF examination were done in all patients. CT scan of
head/USG cranium was done where feasible. After processing , the CSF
sample was divided in four parts and they were subjected to cytological
and biochemical analysis, culture on Bac T/ALERT 3D system, PCR targeting
IS6110 in thermal cyclers (Applied Biosystems) and real time PCR targeting
16SrRNA using light cycler RNA amplification syber green 1 kit (Roche
applied biosciences, Germany).
Majority of our cases and controls were less than 4
years of age. The mean age in study and control groups were 4.4 ± 3.5
years and 5.0 ± 4 years, respectively. Mantoux test was positive in 30% (n=14)
of cases; all the controls were mantoux negative. 53.1% (n=25) of
cases had positive history of contact. 32.7% (n=15) of cases and
75% (n=6) of controls had received BCG vaccination. The mean
duration of illness was 37.6 ± 27.4 days in cases and 26.2 ± 20.8 days
among controls.
Table I shows the sensitivity and specificity
of the four methods. Statistically, real time PCR showed significantly
better results than the other tests, including PCR targeting IS6110 (P<0.05).
The present study, thus shows a good promise for using Real Time PCR
targeting 16SrRNA to diagnose neurotuberculosis in the pediatric
population. It is of particularly greater value in developing countries
where the burden of the disease is high and early diagnosis is crucial to
prevent mortality and morbidity. We conclude that real time PCR technique
is highly sensitive and specific in diagnosing neurotuberculosis in
children.
TABLE I
Sensitivity and Specificity of Various Diagnostic Methods
S. |
Tests |
Total |
Positive |
Total |
Positive |
Sensitivity |
Specificity |
No |
|
cases |
cases |
controls |
controls |
(%) |
(%) |
1 |
Cytology and biochemistry |
47 |
18 |
8 |
0 |
38.3 |
100 |
2 |
BacT/Alert |
47 |
23 |
8 |
0 |
48.9 |
100 |
3 |
PCR IS6110 |
47 |
39 |
8 |
0 |
82.9 |
100 |
4 |
Real time PCR 16SrRNA |
47 |
46 |
8 |
0 |
97.8 |
100 |
Contributors: RD and PS participated in acquisition
of data and manuscript preparation, PS, VMK and DSC participated in
concept, design and critical review, RD, PS and NKY participated in
analysis, interpretation of data and manuscript preparation, RD and VMK
participated in final approval of the version to be published.
Funding: None.
Competing interests: None stated.
References
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3. Broccolo F, Scarpellini P, Locatelli G, Zingale A,
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4565-4572.
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of Childhood Tuberculosis. Indian Pediatr 2004; 41: 146-155.
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