Quality of molecular detection of vancomycin resistance in enterococci: results of 6 consecutive years of Quality Control for Molecular Diagnostics (QCMD) external quality assessment

AbstractThe quality of PCR to detect vancomycin-resistant enterococci (VRE) was evaluated by analysing their performance in six consecutive external quality assessment (EQA) schemes, organized annually since 2013 byQuality Control for Molecular Diagnostics. VRE EQA panels consisted of 12 –14 heat-inactivated samples. Sensitivity was tested withvanA-positiveEnterococcus faecium (E. faecium),vanB-positiveE. faecium, E. faecalis orE. gallinarum orvanC-positiveE. gallinarum in different concentrations. Vancomycin-susceptible enterococci,Staphylococcus aureus or sample matrix was used to study the specificity. Participants were asked to report the VRE resistance status of each sample. The detection rate ofvanA-positive samples was already 95% in the 2013 EQA panel (range 94 –97%) and remained stable over the years. The 2013 detection rate ofvanB-positive samples was 82% but increased significantly by more than 10% in subsequent years (96% in 2014, 95% in 2015, 92% in 2016 and 93% in 2017/2018,p <  0.05). ThevanC detection rate by the limited number of assays specifically targeting this gene was lower compared tovanA/B (range 55 –89%). The number of false positives in the true-negative sample (8% in 2013 to 1.4% in 2018) as well as the van-gene-negative bacterial samples (4% in 2013 to 0% in 2018) declined over the years. In the six years of VRE proficiency testing to date, the detection ofvanA-positive strains was excellent and an increased sensitivity invanB detecti...
Source: European Journal of Clinical Microbiology and Infectious Diseases - Category: Microbiology Source Type: research