A novel strategy based on genomics and specific PCR reveals how a multidrug resistant Mycobacterium tuberculosis strain became prevalent in Equatorial Guinea 15 years after its emergence.

OBJECTIVE: Molecular epidemiology techniques in tuberculosis (TB) can identify high-risk strains that are actively transmitted. We aimed to implement a novel strategy to optimize the identification and control of multidrug-resistant (MDR) TB in a specific population. METHODS: We developed a strain-specific PCR tailored from whole genome sequencing (WGS) data to track a specific MDR prevalent strain in Equatorial Guinea (EG-MDR). RESULTS: The PCR was applied prospectively on remnants of GeneXpert reaction mixtures owing to the lack of culture facilities in Equatorial Guinea. In 147 (93%) of 158 cases, we were able to differentiate between infection by the EG-MDR strain or by any other strain and found that 44% of all rifampicin-resistant TB cases were infected by EG-MDR. We also analysed 93 isolates obtained from Equatorial Guinea 15 years ago, before MDR-TB had become the problem it is today. We found that two of the scarce historical MDR cases were infected by EG-MDR. WGS revealed low variability-six single nucleotide polymorphisms acquired by this strain over 15 years-likely because of the lack in the country of a specific program to treat MDR-TB. CONCLUSIONS: Our novel strategy, which integrated WGS analysis and strain-specific PCRs, represents a low-cost, rapid and transferable strategy that allowed a prospective efficient survey and fast historical analysis of MDR-TB in a population

A novel strategy based on genomics and specific PCR reveals how a multidrug-resistant Mycobacterium tuberculosis strain became prevalent in Equatorial Guinea 15 years after its emergence

et al.[Objective]: Molecular epidemiology techniques in tuberculosis (TB) can identify high-risk strains that are actively transmitted. We aimed to implement a novel strategy to optimize the identification and control of multidrug-resistant (MDR) TB in a specific population. [Methods]: We developed a strain-specific PCR tailored from whole genome sequencing (WGS) data to track a specific MDR prevalent strain in Equatorial Guinea (EG-MDR). [Results]: The PCR was applied prospectively on remnants of GeneXpert reaction mixtures owing to the lack of culture facilities in Equatorial Guinea. In 147 (93%) of 158 cases, we were able to differentiate between infection by the EG-MDR strain or by any other strain and found that 44% of all rifampicin-resistant TB cases were infected by EG-MDR. We also analysed 93 isolates obtained from Equatorial Guinea 15 years ago, before MDR-TB had become the problem it is today. We found that two of the scarce historical MDR cases were infected by EG-MDR. WGS revealed low variability-six single nucleotide polymorphisms acquired by this strain over 15 years-likely because of the lack in the country of a specific program to treat MDR-TB. [Conclusions]: Our novel strategy, which integrated WGS analysis and strain-specific PCRs, represents a low-cost, rapid and transferable strategy that allowed a prospective efficient survey and fast historical analysis of MDR-TB in a population.This study was funded by Plan Estatal I+D+I 2013-2016, ISCIII (13/01207; 15/01554) and cofunded by the Fondo Europeo de Desarrollo Regional (FEDER): “Una manera de hacer Europa”. We also received funding from Fondation Merieux (DM/CL/cb15) and a Grant for International Cooperation Projects from the IiSGM (I and II-COOP-INT 2015). L.P. holds a Miguel Servet research grant (CP15/00075), MINECO research grant (SAF2013-43521-R); I.C. holds a European Research Council (ERC) grant (638553-TB-ACCELERATE). Funding was also received from the Spanish Network for Research in Infectious Diseases (REIPI, RD12/0015 to GT).Peer reviewe