Fast-track identification of CTX-M-extended-spectrum-β-lactamase- and carbapenemase-producing Enterobacterales in bloodstream infections: implications on the likelihood of deduction of antibiotic susceptibility in emergency and internal medicine departments

Abstract

This study aims at presenting a reliable fast-track diagnostics for the detection of CTX-M ESBL- (CTX-M-p) and carbapenemase-producers (CA-p) directly from blood cultures (BCs) of patients with Enterobacterales (EB) bloodstream infections (BSIs) admitted in emergency and internal medicine departments and its contribution in estimation of in vitro antibiotic susceptibility. A fast-track workflow including MALDI-TOF species identification and two lateral flow immunochromatographic assays for the detection of CTX-M-p and CA-p directly from BCs was performed in parallel with conventional routine, and results were compared. A total of 236 BCs of patients suffering from EB BSI were included. Accuracy of the fast-track workflow ranged from 99.6 to 100%. Among E. coli isolates, CTX-M-p (20.5%) were susceptible to ceftolozane-tazobactam (C/T, 97%), ceftazidime-avibactam (CZA, 100%), and piperacillin-tazobactam (TZP, 84.8%), whereas CTX-M-and-main-carbapenemases-non-producer (CTX-M-CA-np, 79.5%) isolates were susceptible to all the antibiotics tested. Among K. pneumoniae isolates, CTX-M-p (23.3%) were poorly susceptible to TZP (40%) but widely susceptible to C/T (90%), CZA (100%), and amikacin (90%), whereas CTX-M-CA-np (55.8%) were also susceptible to cefepime. CA-p K. pneumoniae (20.9%) were susceptible to CZA (88.9%). All the species other than E. coli and K. pneumoniae were CTX-M-CA-np and were widely susceptible to the antibiotics tested except for isolates of the inducible and derepressed AmpC- or AmpC/ESBL-p species. Rapid identification of species and phenotype together with knowledge of local epidemiology may be crucial to determine the likelihood of deduction of in vitro antibiotic susceptibility on the same day of positive BC processing.

Direct detection of extended-spectrum-β-lactamase-producers in Enterobacterales from blood cultures: a comparative analysis

“…The Rapid ESBL NP® (Liofilchem, Roseto degli Abbruzzi, Italy) is a colorimetric cefotaxime hydrolysis-based assay able to detect the presence/absence of any type of ESBLs or the presence of an enzyme or combination of enzymes that can hydrolyze cefotaxime, but which is not inhibited by the addition of tazobactam (i.e., cephalosporinase, ESBL + cephalosporinase, carbapenemase with or without an ESBL) [25,26]. Rapid ESBL NP® test was performed using the bacterial pellet recovered with MBT Sepsityper IVD Kit from 1 mL of positive BC broth, as previously described [11,12,27]. Briefly, after keeping test panel at room temperature for 10 min, 400 μL of lysis buffer was added to the bacterial pellet and vortexed for 5 s. After 15 min, 100 μL of the solution obtained was dispensed into each well (A, B, and C) of the test cassette.…”

“…The NG CTX-M MULTI® assay (NG Biotech, Guipry, France) is a lateral flow immunoassay exploiting monoclonal antibodies specific for the specific detection of CTX-M-type (groups 1, 2, 8, 9, and 25) ESBL enzymes only [10][11][12]. As opposed to the Rapid ESBL NP test, this technique is not aimed to identify all types of ESBL producers.…”

“…to delay obtention of results in critical scenarios as that of management of BSI patients. Various phenotypic tests that can detect ESBLs have been evaluated directly from EBpositive blood cultures (BCs) to provide result on the same day of positive BC processing with variable specificity and sensitivity [10][11][12][13][14][15][16][17][18][19][20][21][22][23]. Although the benefit in reducing TAT is recognized [12,23], evidence of the detection of ESBL producers directly from EB-positive BCs in clinical routine are limited.…”

“…Various phenotypic tests that can detect ESBLs have been evaluated directly from EBpositive blood cultures (BCs) to provide result on the same day of positive BC processing with variable specificity and sensitivity [10][11][12][13][14][15][16][17][18][19][20][21][22][23]. Although the benefit in reducing TAT is recognized [12,23], evidence of the detection of ESBL producers directly from EB-positive BCs in clinical routine are limited. Therefore, this study was aimed at evaluating the performance of three methods for direct detection of ESBL producers from BSI, none of them being molecular based and all of them being very recently commercialized.…”

Detection of Multidrug-Resistant Enterobacterales—From ESBLs to Carbapenemases

“…Analyzing a total of 236 episodes of Enterobacterales blood stream infections, a good agreement with conventional phenotypic results was recorded. Time-to-result (defined starting point was the processing of positive BC) for this fast-track workflow was 42 min compared to 38 h for the conventional workflow (identification and AST from overnight cultures) [ 150 ]. In practice this means that that therapeutic and antibiotic stewardship interventions can be implemented one to two days earlier with this new protocol, which highlights the potential of ICT used in innovative workflows to accelerate clinical decision making.…”