Blood cultures for the diagnosis of multidrug-resistant and extensively drug-resistant tuberculosis among HIV-infected patients from rural South Africa: a cross-sectional study

Scott K Heysell,Gerald Friedland,Palav Babaria,Sarita Shah,Lynette Roux,Tania A Thomas,Anthony P Moll,Neel R Gandhi,Umesh Lalloo,Yacoob Coovadia,François J Eksteen

doi:10.1186/1471-2334-10-344

Abstract

BackgroundThe yield of mycobacterial blood cultures for multidrug-resistant (MDR) and extensively drug-resistant tuberculosis (XDR-TB) among drug-resistant TB suspects has not been described.MethodsWe performed a retrospective, cross-sectional analysis to determine the yield of mycobacterial blood cultures for MDR-TB and XDR-TB among patients suspected of drug-resistant TB from rural South Africa. Secondary outcomes included risk factors of Mycobacterium tuberculosis bacteremia and the additive yield of mycobacterial blood cultures compared to sputum culture.ResultsFrom 9/1/2006 to 12/31/2008, 130 patients suspected of drug-resistant TB were evaluated with mycobacterial blood culture. Each patient had a single mycobacterial blood culture with 41 (32%) positive for M. tuberculosis, of which 20 (49%) were XDR-TB and 8 (20%) were MDR-TB. One hundred fourteen (88%) patients were known to be HIV-infected. Patients on antiretroviral therapy were significantly less likely to have a positive blood culture for M. tuberculosis (p = 0.002). The diagnosis of MDR or XDR-TB was made by blood culture alone in 12 patients.ConclusionsMycobacterial blood cultures provided an additive yield for diagnosis of drug-resistant TB in patients with HIV from rural South Africa. The use of mycobacterial blood cultures should be considered in all patients suspected of drug-resistant TB in similar settings.

Highlights

The yield of mycobacterial blood cultures for multidrug-resistant (MDR) and extensively drug-resistant tuberculosis (XDR-TB) among drug-resistant TB suspects has not been described
One-hundred thirty patients suspected of drug-resistant TB had mycobacterial blood cultures performed during the study period and were included for analysis
We found that among a predominantly HIV-infected population of patients suspected of drug-resistant TB, MDR-TB and XDR-TB were isolated in nearly 70% of all positive M. tuberculosis blood cultures

Summary

Introduction

The yield of mycobacterial blood cultures for multidrug-resistant (MDR) and extensively drug-resistant tuberculosis (XDR-TB) among drug-resistant TB suspects has not been described. Previously considered uncommon in high HIV prevalence settings, there has been a 3-4 fold increase in multidrug-resistant (MDR)TB prevalence in southern Africa over the past decade [3,4]. Extensively drug-resistant (XDR)-TB has been reported from all countries in southern Africa. HIV-infected TB patients have higher rates of extrapulmonary disease, atypical clinical presentations, and normal chest radiographs [7,8,9,10]. With the emergence of MDR and XDRTB in HIV-infected populations worldwide [3], it is likely that there will be a consequent rise in extrapulmonary MDR and XDR-TB disease [11]. The diagnosis of drug-resistant TB requires isolation of an organism, or DNA in the case of molecular tests, vigorous efforts to obtain a specimen that may yield

Methods

Results

Discussion

Conclusion