Publication date: Jan 22, 2019
Background A critical gap in tuberculosis (TB) treatment is detection of emergent drug resistance. We hypothesized that advanced phenotyping with whole genome sequencing (WGS) will detect low frequency Mycobacterium tuberculosis (MTB) drug-resistance.Methods We assessed a reporter mycobacteriophage (φGFP10) in vitro to detect drug-resistant subpopulations and predict MTB bactericidal activity in this pilot study. Subsequently, we prospectively studied 20 TB patients with serial φGFP10, Xpert MTB/RIF, and MTB culture through end of treatment. WGS was performed and single nucleotide polymorphisms (SNPs) were examined to detect mixed infection in selected MTB isolates.Results Resistant MTB were detected at 1:100,000 and changes in cytometry gated events were predictive of in vitro MTB bactericidal activity using the φGFP10 assay. Emergent drug-resistance was detected in one patient by φGFP10 at three weeks but not by conventional testing (MTB culture and GeneXpert). WGS revealed a phylogeographically distinct extensively drug-resistant tuberculosis (XDR-TB) genome, identical to an XDR-TB isolate from the patient’s spouse. Variant lineage-specific SNPs were present early, suggesting mixed infection as the etiology of emergent resistance with temporal trends providing evidence for selection during treatment.Conclusions φGFP10 can detect low frequency drug-resistant MTB and with WGS characterize emergent MTB resistance. In areas of high TB transmission and drug resistance, rapid screening for heteroresistance should be considered.
O’Donnell, Larsen, M.H., Brown, T.S., Jain, P., , Munsamy, Wolf, A., Uccellini, L., Karim, F., D’Olivera, T., Mathema, B., Jacobs, W.R., and Pym, A. Early detection of emergent extensively drug resistant tuberculosis (XDR-TB) by flow cytometry-based phenotyping and whole genome sequencing. 04309. 2019 Antimicrob Agents Chemother.
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