Rapid microarray-based assay for detection of pyrazinamide resistant Mycobacterium tuberculosis

Publication date: Available online 30 December 2018

Source: Diagnostic Microbiology and Infectious Disease

Author(s): Juliane Havlicek, Beatrice Dachsel, Peter Slickers, Sönke Andres, Patrick Beckert, Silke Feuerriegel, Stefan Niemann, Matthias Merker, Ines Labugger

Abstract

Pyrazinamide (PZA) is a key antibiotic for the treatment of drug susceptible tuberculosis. PZA-resistance is mainly mediated by mutations in the pncA gene, however the current gold standard is a phenotypic drug susceptibility test requiring a well-adjusted pH-value for reliable results.

Our melting curve assay detects a non-wild type genotype in selected pncA regions in at least 3750 gene copies/mL within 2.5 hours. The prototype assay was further evaluated by analyzing 271 Mycobacterium tuberculosis complex isolates from Swaziland originating from a previously published drug resistance survey and including 118 isolates with pncA mutations. Sensitivity was 83% (95% CI 75%–89%) and specificity was 100% (95% CI 98%–100%). Under consideration of further improvements with regard to the target range our melting curve assay has the potential as a rapid rule-in test for PZA susceptibility (wild type pncA), however false resistant results (mutant pncA, but PZA susceptible) cannot be ruled out completely.

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