Performance of the BD Phoenix CPO detect assay for detection and classification of carbapenemase-producing organisms

Abstract

Increasing worldwide, prevalence of carbapenem-resistant gram-negative bacteria demands urgent a need for rapid detection and accurate identification of carbapenemases. The BD Phoenix CPO detect (PCD) assay possesses an in-built capacity for parallel susceptibility testing and detection of carbapenemases. Here, the ability of the assay to detect and classify carbapenemase production was tested in a collection of carbapenem-resistant Enterobacterales and non-fermentative gram-negative rods. The ability of the PCD assay to detect and classify carbapenemases was investigated in a collection of 194 clinical, carbapenem-resistant isolates (Enterobacterales [n = 65]; non-fermentative gram-negative rods [n = 129]). AST results were compared to MICS determined by gradient diffusion to determine accuracy of the PCD assay. The accuracy of the PCD assay to detect carbapenemases was compared to the results of molecular isolate characterization using a LDT multiplex carbapenemase PCR assay. All 194 isolates classified as carbapenem-resistant by reference susceptibility testing were also classified correctly as CRO by the PCD assay. Performance analysis of the PCD assay to detect carbapenemase production revealed an overall sensitivity of 98.29% and specificity of 17.95% for the detection of carbapenemase production. For the classification of carbapenemases classes A, B, and D, the PCD correctly classified 79.17% Enterobacterales and 67.16% non-fermentative gram-negative rods. The PCD assay is a reliable tool for the detection of carbapenem resistance and allows for parallel analysis of carbapenemase production. However, while sensitivity is high, low specificity in carbapenemase detection and erroneous classification demands mandatory confirmation by alternative methods, especially in non-fermentative gram-negative bacteria.

Usefulness of BioFire FilmArray BCID2 for Blood Culture Processing in Clinical Practice

“… a β-Lactamase-encoding genes were detected by PCR ( 15 ). b β-Lactamase-encoding genes were identified from whole-genome assemblies using abricate ( https://github.com/tseemann/abricate ) and the NCBI bacterial antimicrobial resistance reference gene database ( https://www.ncbi.nlm.nih.gov/bioproject/313047 ).…”

“…Importantly, carbapenem resistance in Enterobacter spp. and P. aeruginosa is related to carbapenemase-independent mechanisms in around 80% of isolates ( 15 ). Although BCID2 correctly identified carbapenemases in two clinical specimens and blood cultures spiked with carbapenemase-producing Enterobacterales , it is reasonable to speculate that broader routine use of BCID2 will result in relevant error rates in the valid prediction of carbapenem susceptibilities in Gram-negative isolates.…”

“…Isolates with inconclusive phenotypic results were further characterized by an in-house PCR assay to detect bla CTX-M , bla TEM , and bla SHV ( 13 ). Isolates exhibiting a carbapenem-resistant phenotype were tested for bla OXA-48 -like, bla VIM-2 , bla KPC , bla NDM-1 , bla IMP , bla BIC , bla GES , bla NMC-A/IMI , and bla SME using an in-house PCR panel ( 14 , 15 ).…”

“…Isolates with inconclusive phenotypic results were further characterized by an in-house PCR assay to detect bla CTX-M , bla TEM , and bla SHV (13). Isolates exhibiting a carbapenem resistant phenotype were tested for bla OXA-48 -like, bla VIM-2 , bla KPC , bla NDM-1 , bla IMP , bla BIC , bla GES , bla NMC-A/IMI , and bla SME using an in-house PCR panel (14,15). Specimens growing Gram-positive cocci were inoculated into a GeneXpert SA/MRSA cartridge (cluster forming cocci) or into a vanA/vanB cartridge (Gram stain suggestive of enterococci) (both Cepheid, Sunnydale, CA, USA) (7).…”

Efficacy and safety of polymyxin B in carbapenem-resistant gram-negative organisms infections

“…It is necessary to strengthen the close connection between microbial laboratories and clinical departments, and to treat anti-infection according to microbiological results as soon as possible. The new prediction indexes and rapid diagnostic techniques can shorten the time for determining the use of polymyxin B, benefit those patients who really need to use polymyxin B as soon as possible, and limit those patients who do not have indications to be treated with polymyxin B [ 18 – 21 ]. The guidelines for sepsis also show [ 11 ] that once the diagnosis of sepsis and etiological examination are made clear in clinic, anti-infection treatment should be carried out as soon as possible, and the antibiotic regimen should be adjusted early according to the results of bacterial susceptibility.…”