Indian Journal of Medical Microbiology IAMM  | About us |  Subscription |  e-Alerts  | Feedback |  Login   
  Print this page Email this page   Small font sizeDefault font sizeIncrease font size
 Home | Ahead of Print | Current Issue | Archives | Search | Instructions  
Users Online: 2328 Official Publication of Indian Association of Medical Microbiologists 
  Search
 
  
 ~  Similar in PUBMED
 ~  Search Pubmed for
 ~  Search in Google Scholar for
 ~  Article in PDF (339 KB)
 ~  Citation Manager
 ~  Access Statistics
 ~  Reader Comments
 ~  Email Alert *
 ~  Add to My List *
* Registration required (free)  

 
 ~  References
 ~  Article Figures
 ~  Article Tables

 Article Access Statistics
    Viewed520    
    Printed9    
    Emailed0    
    PDF Downloaded74    
    Comments [Add]    

Recommend this journal

 


 
  Table of Contents  
CORRESPONDENCE
Year : 2019  |  Volume : 37  |  Issue : 3  |  Page : 448-449
 

Utility of Xpert® MTB/RIF in the diagnosis of extrapulmonary tuberculosis


1 Department of Infectious Diseases, Sri Ramachandra Medical Centre, Chennai, Tamil Nadu, India
2 Department of Infectious Diseases, Apollo Hospitals, Chennai, Tamil Nadu, India
3 Molecular Diagnostics Laboratory, Apollo Hospitals, Chennai, Tamil Nadu, India

Date of Submission19-Sep-2019
Date of Decision27-Oct-2019
Date of Acceptance27-Oct-2019
Date of Web Publication29-Jan-2020

Correspondence Address:
Dr. Vidya Krishna
A-15, Sterling Ganges, 214, Mount Poonamallee Road, Kattupakkam, Chennai - 600 056, Tamil Nadu
India
Login to access the Email id

Source of Support: None, Conflict of Interest: None


DOI: 10.4103/ijmm.IJMM_19_149

Rights and Permissions



How to cite this article:
Krishna V, Gopalakrishnan R, Tarigopula A, Panchatcharam SN, Dorairajan SK, Venkatasubramanian R. Utility of Xpert® MTB/RIF in the diagnosis of extrapulmonary tuberculosis. Indian J Med Microbiol 2019;37:448-9

How to cite this URL:
Krishna V, Gopalakrishnan R, Tarigopula A, Panchatcharam SN, Dorairajan SK, Venkatasubramanian R. Utility of Xpert® MTB/RIF in the diagnosis of extrapulmonary tuberculosis. Indian J Med Microbiol [serial online] 2019 [cited 2020 Apr 9];37:448-9. Available from: http://www.ijmm.org/text.asp?2019/37/3/448/274087




Respected Editor,

In most studies on Xpert® MTB/RIF assay in extrapulmonary tuberculosis (EPTB), it has usually been compared to culture, which is known to be a suboptimal reference standard for EPTB.[1],[2] We share the results of our retrospective study on patients ≥18 years with suspected EPTB between January and July 2015, in which we compared Xpert® MTB/RIF to a composite reference standard (CRS). Patients with proven alternate diagnosis, those with incomplete records and who died or were lost to follow-up within 3 months of starting antituberculous therapy (ATT) were excluded from the study. The patients were classified based on CRS as follows: confirmed TB (microbiologically confirmed), probable TB (clinical symptoms, radiological findings and/or histology/cytology suggestive of TB, no microbiological evidence), possible TB (follow-up indicated response to empirical ATT after 3 months) and not TB (proven alternate diagnoses).

After exclusion, 225 (75 confirmed and 150 probable) of 752 patients with EPTB were included in the study analysis [Figure 1]. Samples included pus (31, 13%), tissue (144, 61%), fluids (40, 17%) and cerebrospinal fluid (20, 8.5%). The rates of culture and Xpert® MTB/RIF positivity in different samples are depicted in [Table 1]. Xpert® MTB/RIF was positive in 68.5%, smear in 11.2% and culture in 35.6% of the cases.
Figure 1: Study flow chart

Click here to view
Table 1: Sensitivity of Xpert® MTB RIF and culture in various specimens

Click here to view


Xpert® MTB/RIF had better sensitivity than cultures for all body sites, especially for lymph node and osteo-articular TB. It had greater sensitivity in tissues than fluids in the diagnosis of pleural and abdominal TB (74% vs. 22%). In all patients with alternate diagnoses, Xpert® MTB/RIF assay was negative. The sensitivity of Xpert® MTB/RIF to identify rifampicin resistance was 100% but specificity was 84.5%.

In conclusion, Xpert® MTB/RIF assay detected >2/3rd of EPTB cases, was 100% specific and almost twice as sensitive as mycobacterial culture. Our findings support the WHO recommendations to routinely use Xpert® MTB/RIF assay in the diagnosis of EPTB.[3]

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
 ~ References Top

1.
Maynard-Smith L, Larke N, Peters JA, Lawn SD. Diagnostic accuracy of the Xpert MTB/RIF assay for extrapulmonary and pulmonary tuberculosis when testing non-respiratory samples: A systematic review. BMC Infect Dis 2014;14:709.  Back to cited text no. 1
    
2.
Penz E, Boffa J, Roberts DJ, Fisher D, Cooper R, Ronksley PE, et al. Diagnostic accuracy of the Xpert® MTB/RIF assay for extra-pulmonary tuberculosis: A meta-analysis. Int J Tuberc Lung Dis 2015;19:278-84, i-iii.  Back to cited text no. 2
    
3.
World Health Organization. Xpert MTB/RIF assay for the Diagnosis of Pulmonary and Extrapulmonary TB in Adults and Children. Policy Update. World Health Organization; 2013. Available from: https://apps.who.int/iris/bitstream/handle/10665/112472/9789241506335_eng.pdf?sequence=1. [Last accessed on 2019 Oct 09].  Back to cited text no. 3
    


    Figures

  [Figure 1]
 
 
    Tables

  [Table 1]



 

Top
Print this article  Email this article
 

    

2004 - Indian Journal of Medical Microbiology
Published by Wolters Kluwer - Medknow

Online since April 2001, new site since 1st August '04