Direct Detection by the Xpert MTB/RIF Assay and Characterization of Multi and Poly Drug-Resistant Tuberculosis in Guinea-Bissau, West Africa

Paulo Rabna,Victor F Gomes,Diana Machado,Jorge Atouguia,Jorge Ramos,Ana Armada,Lilica Sanca,Fina Vieira,Elisabete Martins,Morto Mané,Gema Ponce,Amabélia Rodrigues,Isabel Couto,Miguel Viveiros,Raffaella Colombatti,Fabio Riccardi,João Perdigão,Joana Sotero,Isabel Portugal

doi:10.1371/journal.pone.0127536

Abstract

BackgroundThis study aimed to evaluate the usefulness of the Xpert MTB/RIF assay for the rapid direct detection of M. tuberculosis complex (MTBC) strains and rifampicin resistance associated mutations in a resource-limited setting such as Guinea-Bissau and its implications in the management of tuberculosis (TB) and drug resistant tuberculosis, complementing the scarce information on resistance and genotypic diversity of MTBC strains in this West African country.Methods and ResultsThis cross-sectional prospective study included 100 consecutive TB patients with positive acid-fast smears at two months of anti-tuberculosis treatment or in a re-treatment situation, between May and December 2012. Resistance to rifampicin was detected using the GeneXpert system and the Xpert MTB/RIF assay. MTBC isolates obtained with the BACTEC MGIT 960 system were tested for susceptibility to first- and second-line anti-tuberculosis drugs. Overall, the prevalence of multidrug-resistant tuberculosis (MDR-TB) was found to be 9 cases. Of these, 67% (6 patients) of confirmed MDR-TB cases had no past history of TB treatment and 33% (3 patients) were previously treated cases. Extensively drug-resistant TB was not found. Molecular typing of the MDR-TB strains revealed recent transmission patterns of imported MDR strains.ConclusionsThe Xpert MTB/RIF assay was reliable for the detection of rifampicin resistant MTBC strains directly from sputum samples of patients undergoing first-line treatment for two months, being more trustworthy than the simple presence of acid-fast bacilli in the smear. Its implementation is technically simple, does not require specialized laboratory infrastructures and is suitable for resource-limited settings when a regular source of electricity and maintenance is available as well as financial and operation sustainability is guaranteed by the health authorities. A high prevalence of MDR-TB among patients at risk of MDR-TB after two months of first-line treatment was found, in support of the WHO recommendations for its use in the management of this risk group.

Highlights

Despite all the scientific and technological advances, tuberculosis (TB) remains a serious and important global health problem [1]
This study aimed to evaluate the usefulness of the Xpert MTB/RIF assay for the rapid direct detection of M. tuberculosis complex (MTBC) strains and rifampicin resistance associated mutations in a resource-limited setting such as Guinea-Bissau and its implications in the management of tuberculosis (TB) and drug resistant tuberculosis, complementing the scarce information on resistance and genotypic diversity of MTBC strains in this West African country
MTBC isolates obtained with the BACTEC MGIT 960 system were tested for susceptibility to first- and second-line anti-tuberculosis drugs

Summary

Introduction

Despite all the scientific and technological advances, tuberculosis (TB) remains a serious and important global health problem [1]. Multidrug resistant TB, and in particular extensively drug resistant TB (XDR-TB), are more expensive to treat, with a survival rate in patients co-infected with HIV that is lower in comparison with drug susceptible TB. This poses a particular problem for countries with few resources where the prevalence of TB and HIV is high and the access to therapeutic regimens of first- and second-line is limited [3,4]. The increasing course of drug resistant TB, of paucibacillary and extra-pulmonary cases, as well as of HIV co-infection rates worldwide, demands for faster methods to detect TB and MDR-TB, a key factor in the management and treatment of TB patients. This study aimed to evaluate the usefulness of the Xpert MTB/RIF assay for the rapid direct detection of M. tuberculosis complex (MTBC) strains and rifampicin resistance associated mutations in a resource-limited setting such as Guinea-Bissau and its implications in the management of tuberculosis (TB) and drug resistant tuberculosis, complementing the scarce information on resistance and genotypic diversity of MTBC strains in this West African country

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