Skip to content
Home
About Us
Resources
Profiles Metrics
Authors Directory
Institutions Directory
Top Authors
Top Institutions
Top Sponsors
AI Digest
Contact Us
Menu
Home
About Us
Resources
Profiles Metrics
Authors Directory
Institutions Directory
Top Authors
Top Institutions
Top Sponsors
AI Digest
Contact Us
Home
About Us
Resources
Profiles Metrics
Authors Directory
Institutions Directory
Top Authors
Top Institutions
Top Sponsors
AI Digest
Contact Us
Menu
Home
About Us
Resources
Profiles Metrics
Authors Directory
Institutions Directory
Top Authors
Top Institutions
Top Sponsors
AI Digest
Contact Us
Publication Details
AFRICAN RESEARCH NEXUS
SHINING A SPOTLIGHT ON AFRICAN RESEARCH
medicine
Xpert MTB/RIF as a measure of sputum bacillary burden: Variation by HIV status and immunosuppression
American Journal of Respiratory and Critical Care Medicine, Volume 189, No. 11, Year 2014
Notification
URL copied to clipboard!
Description
Rationale: Xpert MTB/RIF cycle threshold values are a measure of sputum mycobacterial burden. Data on the impact of HIV infection and immunosuppression on this measure are limited. Objectives: Examine the impact of HIV status and level of immunosuppression on the distribution of mean cycle threshold values, and the correlation of cycle threshold values and smear microscopy grade with time to culture positivity. Methods: Paired sputum samples from 2,406 individuals with suspected pulmonary tuberculosis in South Africa were tested by Xpert MTB/RIF, concentrated smear microscopy, and liquid culture to quantify bacterial burden using cycle threshold values, smear grading, and time to culture positivity. Measurements and Main Results: Cycle threshold values were lower in HIV-uninfected versus HIV-infected individuals (22.9 vs. 26.6; P < 0.001). Among HIV-infected, CD4 count was an independent predictor of cycle threshold value, with an average increase of 1.50 cycles for CD4 count greater than or equal to 200 (P 0.071) and 3.66 cycles for CD4 count less than 200 (P < 0.001) compared with HIV-uninfected individuals. Correlation between cycle threshold value and time to culture positivity was similar to that between smear status and time to culture positivity (both Spearman ρ 0.58). The strength of correlation between measures decreased as the level of immunosuppression increased. A cycle threshold value cutoff of 28 had good predictive value for smear positivity. Conclusions: We observed decreasing bacillary burden with increasing level of immunosuppression as measured by Xpert MTB/RIF cycle threshold values. A cycle threshold value of 28 can be used as a measure of bacterial burden and smear status in a high HIV burden setting. Copyright © 2014 by the American Thoracic Society.
Authors & Co-Authors
Hanrahan, Colleen F.
United States, Chapel Hill
The University of North Carolina at Chapel Hill
Theron, Grant
South Africa, Cape Town
University of Cape Town
Bassett, Jean
South Africa, Johannesburg
Witkoppen Health and Welfare Centre
Dheda, Keertan U.J.
South Africa, Cape Town
University of Cape Town
Scott, Lesley Erica
South Africa, Johannesburg
University of the Witwatersrand
Stevens, Wendy Susan
South Africa, Johannesburg
University of the Witwatersrand
Sanne, Ian M.
South Africa, Johannesburg
National Health Laboratory Service
South Africa, Johannesburg
Right to Care
van Rie, Annelies
United States, Chapel Hill
The University of North Carolina at Chapel Hill
Statistics
Citations: 54
Authors: 8
Affiliations: 6
Identifiers
Doi:
10.1164/rccm.201312-2140OC
ISSN:
1073449X
Research Areas
Infectious Diseases
Study Locations
South Africa