The Gold Standard test to identify hypervirulent Klebsiella pneumoniae is the virulence gene array (VGA) assay. This test is a molecular-based method that detects the presence of genes associated with hypervirulence in K. pneumoniae.
The VGA assay is a multiplex PCR-based assay that can detect the presence of 12 genes that are known to be associated with hypervirulence in K. pneumoniae. These genes include:
blaKPC: a gene that confers carbapenem resistance
blaNDM: a gene that confers carbapenem resistance
blaOXA: a gene that confers oxacillin resistance
blaIMP: a gene that confers imipenem resistance
blaVIM: a gene that confers vim-2 carbapenem resistance
blaGIM: a gene that confers imipenem-re resistance
blaSIM: a gene that confers sim-1 carbapenem resistance
blaAmpC: a gene that confers ampC beta-lactamase production
blaDHA: a gene that confers DHA-1 carbapenem resistance
blaOXA-48: a gene that confers OXA-48 carbapenem resistance
blaOXA-101: a gene that confers OXA-101 carbapenem resistance
blaGES-1: a gene that confers GES-1 carbapenem resistance
The VGA assay is a highly sensitive and specific test that can detect the presence of these genes in K. pneumoniae isolates. It has been widely used in clinical settings to identify hypervirulent K. pneumoniae strains and to guide antimicrobial therapy.
It's important to note that the VGA assay is not a perfect test, and false negatives can occur in some cases. Therefore, it's important to use the VGA assay in combination with other diagnostic tests, such as phenotypic susceptibility testing and whole-genome sequencing, to confirm the results and ensure accurate identification of hypervirulent K. pneumoniae strains.