Abstract
Bloodstream infections caused by carbapenemase-producing Enterobacteriaceae (CPE) are associated with treatment failure and increased mortality. Detection of CPE from blood cultures (BC) by standard methods takes 16–72 hours, which can delay the initiation of appropriate antimicrobial therapy and compromise patient outcome. In the present study, we developed and evaluated a new method for the rapid detection of carbapenemases directly from positive BC using a new multiplex immunochromatographic test (ICT). The new ICT was assessed using 170 molecularly characterized Enterobacteriaceae clinical isolates including 126 CPE (OXA-48-like (N = 79), KPC (N = 18) and NDM (N = 29)). After spiking with bacteria and incubation in a BC system, blood from positive BC bottles was hemolyzed, bacteria concentrated by centrifugation and lysed. The lysate was transferred to the RESIST-3 O.K.N. ICT (Coris BioConcept, Gembloux, Belgium), which detects OXA-48-like, KPC and NDM carbapenemases. The final results of the ICT were read when they became positive, at the latest after 15 min. All CPE isolates (126/126) were correctly detected with the new protocol (100% sensitivity, 100% specificity). There was perfect concordance between ICT results and molecular characterization. Total time to result was 20–45 min.Conclusions: This proof-of-principle study demonstrates that with the newly developed method, OXA-48-like, KPC and NDM carbapenemases can be reliably detected directly from positive BC bottles. The new method is more rapid than other currently available assays and can be performed in any routine microbiology laboratory. This can help to rapidly identify patients with CPE BSI and optimize the management of patients with these difficult-to-treat infections. Further studies are needed to assess the performance of the ICT in routine diagnostics.
Highlights
With the increase of carbapenemase-producing Enterobacteriaceae (CPE), the treatment of severe bacterial infections has become more difficult, especially in high prevalence regions.Bloodstream infections (BSI) caused by CPE often delay appropriate antimicrobial therapy and are associated with an increased mortality [1]
We developed and evaluated two new protocols for the rapid detection of CPE directly from positive blood cultures using this immunochromatographic test (ICT)
Blood culture bottles were spiked with five different CPE isolates and the blood culture fluid was processed either without any pretreatment or pretreated with four different hemolyzing agents
Summary
With the increase of carbapenemase-producing Enterobacteriaceae (CPE), the treatment of severe bacterial infections has become more difficult, especially in high prevalence regions. Bloodstream infections (BSI) caused by CPE often delay appropriate antimicrobial therapy and are associated with an increased mortality [1]. The rapid detection of CPE as causative pathogens of BSI is of paramount importance, as it has the potential to improve patient management and outcome. OXA-48-like, KPC, VIM, IMP and NDM type carbapenemases are the most important worldwide [2]. The phenotypic detection of carbapenemases can be difficult by standard techniques. The detection of CPE from blood cultures in routine laboratories is lengthy and usually takes 16–
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