Background: the aim of this study was to evaluate the performance of the Liquid Colony™ (LC) generated directly from positive blood cultures (PBCs) by the FAST System (Qvella, Richmond Hill, ON, Canada) for rapid identification (ID) and antimicrobial susceptibility testing (AST) compared with the standard of care (SOC) workflow. Methods: Anonymized PBCs were processed in parallel by the FAST System and FAST PBC Prep cartridge (35 min runtime) and SOC. ID was performed by MALDI-ToF mass spectrometry (Bruker, Billerica, MA, USA). AST was performed by reference broth microdilution (Merlin Diagnostika, Bornheim, Germany). Carbapenemase detection was carried out with the lateral flow immunochromatographic assay (LFIA) RESIST-5 O.O.K.N.V. (Coris, Gembloux, Belgium). Polymicrobial PBCs and samples containing yeast were excluded. Results: 241 PBCs were evaluated. ID results showed 100% genus-level concordance and 97.8% species-level concordance between LC and SOC. The AST results for Gram-negative bacteria showed a categorical agreement (CA) of 99.1% (1578/1593), with minor error (mE), major error (ME), and very major error (VME) rates of 0.6% (10/1593), 0.3% (3/1122), and 0.4% (2/471), respectively. The results from Gram-positive bacteria showed a CA of 99.6% (1655/1662), with mE, ME, and VME rates of 0.3% (5/1662), 0.2% (2/1279), and 0.0% (0/378), respectively. Bias evaluation revealed acceptable results for both Gram-negatives and Gram-positives (−12.4% and −6.5%, respectively). The LC yielded the detection of 14/18 carbapenemase producers by LFIA. In terms of turnaround time, the ID, AST, and carbapenemase detection results were generally obtained one day earlier with the FAST System compared with the SOC workflow. Conclusions: The ID, AST, and carbapenemase detection results generated with the FAST System LC were highly concordant with the conventional workflow. The LC allowed species ID and carbapenemase detection within around 1 h after blood culture positivity and AST results within approximately 24 h, which is a significant reduction in the turnaround time of the PBC workflow.

Background/Objectives: The emergence and spread of carbapenemase-producing Enterobacterales (CPE) represents a significant challenge prompting the need to optimize diagnostic tools to detect CPE carriers. The Xpert^® Carba-R assay (Cepheid, Sunnyvale, CA, USA), a Real-Time PCR-based test, can detect the bla_KPC, bla_VIM, bla_OXA-48, bla_NDM and bla_IMP carbapenemase genes directly from rectal swabs. This study assessed the performance of the Xpert^® Carba-R assay using FecalSwab™ (Copan, Brescia, Italy), a liquid-based collection device. Methods: The first part of the study aimed to establish the FecalSwab^TM volume which gave the most similar Ct values to those obtained by the Transystem™ double swab (Copan). The best volume was then used to assess the limit of detection (LoD) for each target and compare the accuracy of different FecalSwab^TM storage conditions (room temperature or 4 °C after 16 h compared to T₀). Results: The results indicated that using 200 µL of the FecalSwab™ medium provided reliable Ct values, with the lowest number of invalid samples compared to traditional methods. The average LoDs for different carbapenemases ranged from 4.7 × 10³ to 6.8 × 10³ CFU/mL. FecalSwab™ showed a better performance after 16 h at room temperature compared to storage at 4 °C. Conclusions: This study supports single sampling with the FecalSwab™ medium for both molecular and cultural methods, for the potential optimization of CPE screening.

Background/Objectives: Bloodstream infections (BSIs) are a global healthcare issue associated with high mortality rates. Rapid diagnosis is of importance for the early selection of targeted therapy to improve patient outcomes. The use of rapid molecular assays with positive blood culture (BC) allows the identification (ID) of pathogens and the most relevant resistance determinants (RDs) in a shorter turnaround time, compared to standard culture. In this study, the performances of a new syndromic panel to determine the IDs and RDs of Gram-negative (GN) and Gram-positive (GP) bacteria were investigated in comparison with a standard-of-care (SoC) workflow. Methods: Two hospitals processed residual positive BC samples from non-replicated patients using Molecular Mouse (MM) Sepsis panels (Alifax, Padova, Italy) for GP ID, GN ID and RD detection. Results were compared with an SOC workflow based on subculture, ID by MALDI-ToF mass spectrometry, phenotypic antibiogram, and real-time PCRs for RDs from isolated colonies. Results: A total of 140 and 136 residual positive BC samples were found to be valid for MM-ID and RD, respectively, yielding 76 GN and 76 GP species. Overall ID agreement at the species level was 136/152 (89%). RD agreement was 144/146 (99%). Regarding GN and GP species, ID agreement was 68/76 (89%) and 70/76 (92%), respectively. Conclusions: MM showed high sensitivity in RD detection; however, some discrepancies with results of the SoC workflow were observed, represented by reduced sensitivity for some species-specific IDs. Panel size and compact instrument dimension can be seen as the principal advantage of this modular molecular assay for the rapid detection of pathogens responsible for BSIs.