|Year : 2013 | Volume
| Issue : 2 | Page : 199-200
Polymerase chain reaction for the diagnosis of extra-pulmonary tuberculosis: Need of the hour
P Sharma, P Gill, A Aggarwal
Department of Microbiology, Sri Guru Ramdas Institute of Medical Sciences and Research, Vallah, Amritsar, India
|Date of Submission||09-Jun-2012|
|Date of Acceptance||28-Sep-2012|
|Date of Web Publication||19-Jul-2013|
Department of Microbiology, Sri Guru Ramdas Institute of Medical Sciences and Research, Vallah, Amritsar
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Sharma P, Gill P, Aggarwal A. Polymerase chain reaction for the diagnosis of extra-pulmonary tuberculosis: Need of the hour. Indian J Med Microbiol 2013;31:199-200
|How to cite this URL:|
Sharma P, Gill P, Aggarwal A. Polymerase chain reaction for the diagnosis of extra-pulmonary tuberculosis: Need of the hour. Indian J Med Microbiol [serial online] 2013 [cited 2020 Jun 5];31:199-200. Available from: http://www.ijmm.org/text.asp?2013/31/2/199/115234
With reference to the article on "Need to establish importance of polymerase chain reaction (PCR) for tuberculosis (TB) in smear as well as culture negative non-respiratory samples" published in October 2011 issue of the journal,  we would like to share our experience of using PCR for the diagnosis of extra-pulmonary TB.
The authors have carried out a retrospective study of 98 extra-pulmonary samples collected over a period of 3½ years. Out of 98 samples in their study, 20 were positive by PCR and none were positive by smear or culture. However, the authors have not specified whether they performed a uniplex, multiplex, or nested PCR. Neither have they specified the target sequence which has been targeted in the PCR.
In a similar study carried out in Department of Microbiology at our institute, nested PCR, targeting IS6110 primer specific for Mycobacterium Tuberculosis complex, was carried out. An amplification product of size 123 bp was indicative of infection with MTB complex [Figure 1]. The amplification product of internal control deoxyribonucleic acid (DNA) was 340 bp. DNA of H37Rv strain was taken as positive control.
|Figure 1: Agarosegel electrophoresis of products amplifi ed by nested polymerase chain reaction. Lane 1: Deoxyribonucleic acid molecular weight ladder; Lane 2: Positive control with band at 123 bp; Lane 3:|
Negative control with no band; Lane 4: Sample 1 with band at 340°bp, result is considered negative; Lane 5: Sample 2 with band at 340°bp and 123°bp, result is positive; Lane 6: Sample 3 with band at 340°bp and 123°bp, result is positive; Lane 7: Sample 4 with band at 340°bp and 123°bp, result is positive; Lane 8: Sample 5 with band at 340°bp, result is considered negative
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We received 101 extra-pulmonary samples, with a clinical suspicion of TB, over a period of 1 year (May 2011-May 2012). Out of 101 samples, 7 were positive by nested PCR [Table 1] and none were positive by smear or culture.
We opted for nested PCR, as sensitivity and specificity is considerably improved in nested PCR. If system is adequately standardized, evaluated and precaution for avoiding the contamination are taken, PCR can play a very useful role in paucibacillary extra-pulmonary forms of TB. This point has been further reinforced by a recent study carried out by Mauraya et al.,  who found a significant role of PCR in strengthening the diagnosis of extra-pulmonary TB especially targeting IS6110.
| ~ References|| |
|1.||Gupta V, Singla N, Garg R, Gulati N, Rani H, Chander J. Need to establish importance of polymerase chain reaction for tuberculosis in smear as well as culture negative non-respiratory samples. Indian J Med Microbiol 2011;29:445-6. |
|2.||Maurya AK, Kant S, Nag VL, Kushwaha R, Dhole TN. Detection of 123 bp fragment of insertion element IS6110 Mycobacterium tuberculosis for diagnosis of extrapulmonary tuberculosis. Indian J Med Microbiol 2012;30:182-6. |