NitroSpeed-carba NP test for rapid detection and differentiation between different classes of carbapenemases in Enterobacterales

A biochemical test (NitroSpeed-Carba NP test) was developed to identify carbapenemase production in Enterobacterales and to discriminate between the different types of clinically significant carbapenemases (Ambler classes A, B, and D). It is based on two main features, namely, the hydrolysis by all β-lactamases, including carbapenemases of the nitrocefin substrate, and the capacity of ertapenem to prevent this hydrolysis for all β-lactamases except carbapenemases. Specific carbapenemase inhibitors of class A (avibactam, vaborbactam), class B (dipicolinic acid), and class D (avibactam) were used to inhibit the nitrocefin hydrolysis and to allow the identification of the carbapenemase types with a turnaround time of ca. 30 min. The test was evaluated with a collection of 248 clinical enterobacterial isolates, including 148 carbapenemase producers and 100 non-carbapenemase producers. Its overall sensitivity and specificity were 100% and 97%, respectively, including detection of all types of OXA-48-like carbapenemases. For the detection of the carbapenemase type, including strains that produce double carbapenemases, the sensitivity was 100%, 97%, and 100% for the detection of classes A, B, and D, respectively. This easy-to- implement test may contribute to optimization of the choice of the β-lactam/β- lactamase inhibitor combinations for treating infection due to carbapenemase producers

Fast and reliable detection of carbapenemase genes in various Gram negatives using a new commercially available fluorescence-based real-time polymerase chain reaction platform

The Revogene® Carba C assay is a real-time polymerase chain reaction–based assay that runs on the microfluidic Revogene platform. It was recently designed for the detection of genes encoding the 5 major carbapenemases (NDM, VIM, IMP, KPC, and OXA-48) from various Gram-negatives. A total of 145 clinical Gram-negative strains (96 carbapenemase producers and 49 non–carbapenemase producers) were tested. The overall sensitivity and specificity were 100%. All strains co-producing double carbapenemases have been correctly detected. All non–carbapenemase producers and nontargeted carbapenemase producers gave a negative result. The sample preparation was easy to handle, taking around 5 to 10 min per isolate, with a run time of approximately 70 min. This assay is a rapid, easy-to-perform, reliable tool to detect the most common carbapenemases, with excellent sensitivity and specificity regardless of the host bacteria. Given its user friendliness, simplicity, and short time to result, the Revogene® Carba C assay is suitable for microbiology laboratories

Rapid ESBL NP test for rapid detection of expanded-spectrum β-lactamase producers in enterobacterales

Objectives: To evaluate the biochemical Rapid ESBL NP® (Liofilchem, Italy) for the rapid detection of extended-spectrum β-lactamases (ESBLs) in Enterobacterales.Methods: A total of 100 clinical gram-negative strains (40 ESBL producers with or without cephalosporinase, 43 carbapenemase producers with or without additional ESBLs, 8 AmpC-type producers, 6 penicillinase producers, and 3 non-β-lactamase producers) were tested using this colorimetric technique.Results: The overall sensitivity and specificity of the test were found to be 93.9% and 98.5%, respectively. This test is rapid (turn-around-time of 40–45 minutes), easy to perform, and reliable for identification of ESBL producers.Conclusion: The Rapid ESBL NP test allows differentiation between ESBL producers on one hand, and non-ESBL producers or isolates expressing combined mechanisms of resistance on the other hand