Detection of carbapenemase-producing Enterobacterales and the BD Phoenix CPO Detect panel

ABSTRACT

Introduction: Treatment options for infections with carbapenem-resistant Enterobacterales are strongly limited. New antimicrobials are not effective against all types of carbapenemases. Therefore, rapid and reliable antimicrobial susceptibility testing and identification of the resistance mechanism are important.

Areas covered: We assess several methods to determine carbapenemase production of Enterobacterales in culture and discuss the value of the novel automated BD Phoenix CPO Detect (BDPCPO) panel for the detection and classification of carbapenemases.

Expert opinion: The meropenem minimum inhibitory concentration (MIC) range used in the BDPCPO panel includes the EUCAST screening breakpoint for the detection of carbapenemase producers. The phenotypic, inhibitor-based assay for detection of carbapenemase activity in the BDPCPO panel displays high sensitivity for carbapenemase detection while its specificity is modest. Therefore, confirmation testing of positive results is warranted. Nevertheless, implementing the BDPCPO panel has the potential to reduce time-to-result for detection and classification of carbapenemase producers.

KEYWORDS:

• Ambler class
• carbapenemases
• Enterobacterales
• phenotypic testing

Article Highlights

• Assessment and classification of carbapenemases is not only critical for epidemiological purposes but also for treating patients since novel antimicrobials do not target all classes of carbapenemases.

• Direct detection of carbapenemase proteins or nucleic acid sequences requires a priori knowledge of genes and variants that express carbapenemases. This is why these technologies are prone to fail in identifying new carbapenemase genes and variants as well as combined resistance mechanisms that reduce susceptibility to carbapenems.

• Therefore, phenotypic assessment of carbapenemase production is still critically needed even though, in general, these tests require bacterial colonies.

• Automated phenotypic AST facilitates and standardizes high throughput antimicrobial susceptibility testing.

• Four studies validated the BDPCPO assay for automated carbapenemase detection. This assay has an excellent sensitivity. However, due to its low specificity (especially in isolates where no Ambler class could be attributed), a confirmatory testing of carbapenemase-positive isolates is required.

Declaration of Interest

Michaela Simon has received speaker fees from BD. Authors have nothing else to declare. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

Reviewers Disclosure

Peer reviewers on this manuscript have no relevant financial relationships or otherwise to disclose.