Rapid detection of antimicrobial resistance markers with Allplex™ Entero-DR assay directly from positive blood culture bottles

A method for rapid detection of one extended-spectrum β-lactamase (ESBL) and five carbapenemase-encoding genes as well as vancomycin resistance markers directly from blood cultures using the Allplex™ Entero-DR assay (Seegene, Seoul, South Korea) is presented. Altogether 28 previously well-characterized resistant Gram-negative bacilli and Enterococcus spp., and 142 clinical blood cultures containing Gram-negative bacilli or Gram-positive cocci were analyzed. The method had 100% sensitivity and specificity for detecting bla_OXA-48-like, bla_KPC, bla_VIM, bla_IMP, bla_NDM, bla_CTX-M, vanA, and vanB. The lowest detectable amount of viable cells in blood culture samples were 5.39·10⁴ CFU/mL, 6.66·10⁴ CFU/mL, 5.13·10³ CFU/mL, 6.09·10⁴ CFU/mL, 6.66·10⁴ CFU/mL, 6.66·10⁴ CFU/mL, 3.12·10⁴ CFU/mL, and 5.34·10⁴ CFU/mL for the bla_KPC, bla_OXA-48-like, bla_VIM, bla_IMP, bla_NDM, bla_CTX-M, vanA, and vanB, respectively. The results were available within 90 min from signal positive blood cultures, as no separate DNA extraction steps were needed, and the assay showed no interference from blood or culture media used allowing reliable and simplified detection of the resistance markers.