Do additional colonoscopic biopsies increase the yield of Mycobacterium tuberculosis culture in suspected ileo-colonic tuberculosis?
Isolation of Mycobacterium tuberculosis on culture is vital for differentiating intestinal tuberculosis (ITB) from Crohn’s disease (when histology is not diagnostic) and for diagnosis of multidrug-resistant tuberculosis. The current yield of TB culture (< 50%) from colonoscopic biopsy tissue is not satisfactory.
To determine whether more colonoscopic biopsies can increase the yield of TB culture in patients with ITB.
In this prospective study, in patients who underwent colonoscopy for suspected ITB, four biopsies were taken (container 1) followed by an additional four biopsies (container 2) for TB culture, from involved regions. The culture was done using Mycobacterium Growth Indicator Tube (MGIT) 960. A final diagnosis of ITB was made if TB culture was positive, there was unequivocal histological evidence of TB, or there was unequivocal evidence of TB elsewhere in the body, in the absence of another diagnosis.
Of 182 patients enrolled (mean age 37.5 [SD 17.2] years; 93 [51.5%] women), 70 (38.4%) were finally diagnosed to have ITB. MGIT culture was positive in 29 (41.4%), 27 (38.5%), and 37 (52.8%) of 70 patients from containers 1, container 2, and combined eight biopsies, respectively. The incremental yield of eight biopsies was 11.4% (95% confidence interval [CI] 5.1 to 21.3%) as compared to container 1 and 14.3% (95% CI 7.1 to 24.7%) as compared to container 2.
Additional four (total eight) colonoscopic biopsies improved the yield of TB culture positivity over four biopsies by 11.4% to 14.3%, to 52.8%; this increase is clinically useful.
KeywordsColonoscopy Intestinal tuberculosis MGIT culture
We gratefully acknowledge the help received from Dr. Arun Nanivadekar and from Dr. Sudeep Shah and Dr. Lancelot Pinto (P D Hinduja Hospital) for the statistical inputs and Dr. Rajiv Baijal, Department of Gastroenterology, Jagjivan Ram Hospital, for sending samples for TB culture.
Contribution of authors
Vatsal Mehta: analysis and interpretation of data and drafting of the manuscript. Devendra Desai: concept and study design, study supervision, analysis and interpretation of data, and drafting and critical revision of the manuscript. Philip Abraham: interpretation of data and critical revision of the manuscript. Camilla Rodrigues: blinded conduct of microbiology studies. Ramesh Deshpande: blinded conduct of histology studies. All authors: acquisition of data and approval of final manuscript.
The study was funded by the National Health and Education Society, P D Hinduja Hospital, Mumbai 400 016, India.
Compliance with ethical standards
Conflict of interest
VM, DD, PA, TG, CR, AJ, RD, PS, MI, PR, and AM declare that they have no conflict of interest.
The authors declare that the study was conducted conforming to the Declaration of Helsinki, 1975 (and subsequent revisions) for human rights. Written informed consent was obtained from all participating subjects, and the protocol was reviewed and approved by the institution’s ethics committee. The study was registered to the Clinical Trials Registry - India.
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