Abstract:
Objective: The objective of this study was to compare the diagnostic yield of GeneXpert MTB/RIF with
Ziehl-Neelson (ZN) sputum smear microscopy among index TB cases and their household contacts.
Methods: A cross sectional study was conducted among sputum smear positive index TB cases and their
household contacts in Northern Ethiopia.
Results: Of 353 contacts screened, 41 (11%) were found to have presumptive TB. GeneXpert test done
among 39 presumptive TB cases diagnosed 14 (35.9%) cases of TB (one being rifampicin resistant),
whereas the number of TB cases diagnosed by microscopy was only 5 (12.8%): a 64.3% increased
positivity rate by GeneXpert versus ZN microscopy. The number needed to screen and number needed to
test to diagnose a single case of TB was significantly lower with the use of GeneXpert than ZN
microscopy. Of 119 index TB cases, GeneXpert test revealed that 106 (89.1%) and 5 (4.2%) were positive
for rifampicin sensitive and rifampicin resistant TB, respectively.
Conclusion: GeneXpert test led to increased TB case detection among household contacts in addition to
its advantage in the diagnosis of Rifampicin resistance among contacts and index TB cases. There should
be a consideration in using GeneXpert MTB/RIF as a point of care TB testing tool among high risk groups.
2016 The Authors. Published by Elsevier Ltd on behalf of International Society for Infectious Diseases
