Detection and Characterization of Carbapenemases in Enterobacterales With a New Rapid and Simplified Carbapenemase Detection Method Called rsCDM

Abstract

ObjectiveThis study aimed to develop a new rapid and simplified carbapenemase detection method (rsCDM) for detection and characterization of carbapenemase with 3-aminophenylboronic acid (APBA), ethylenediaminetetraacetic acid (EDTA), and cloxacillin (CLO) β-lactamase inhibitors.MethodsA panel of 182 carbapenem-resistant Enterobacterales (CRE) strains with blaKPC (88), blaNDM (60), blaIMP (10), blaVIM (3), blaOXA-181 (5), blaKPC, and blaNDM (7), porin changes in combination with an extended-spectrum β-lactamase (ESBL) (3) or AmpC hyper-production (6) and 43 carbapenem-susceptible Enterobacterales isolates were used to evaluate the performance of rsCDM and EDTA-carbapenem inactivation method (eCIM). Carbapenemase class was determined with specific inhibitors at 4, 6, and 18 h by rsCDM, and the difference between imipenem (IMI) and meropenem (MEM) disks was simultaneously compared.ResultsThe sensitivity of rsCDM using IMI was 97.1% at the three time points, with a specificity of 100%, independent of the culture duration. Similar to IPM, MEM disk also showed high sensitivity (97.1%) and specificity (100%) at 6 h. And the sensitivity of eCIM was 95.4% and the specificity was 100%. Based on a decision algorithm, the characterization number of IMI and MEM in KPC-producing isolates was 88 vs. 87, metallo-β-lactamases (MBLs) was 73 vs. 72, KPC and NDM carbapenemase was 7 vs. 7 at 4 h, respectively. After 6 h, the category number changed insignificantly except for isolates with combined AmpC overproduction and porin changes, showing an increase in IMI (6) and MEM (2), and there was no difference in the results between 6 and 18 h for the two tablets. OXA-181-producing strains can’t be distinguished by rsCDM. For eCIM, the characterization number in KPC-, OXA- 181-, and MBLs-producing strains was 88, 5, and 72, but it failed to detect multi-enzyme-producing isolates (KPC and NDM).ConclusionrsCDM accurately discriminated carbapenemase within 4 h and could differentiate multi-enzyme (KPC and NDM) and AmpC in conjunction with porin changes strains. Hence, rsCDM represents a rapid, simple, easy readout, and accurate tool that can be used without any specialized equipment.

The application of targeted nanopore sequencing for the identification of pathogens and resistance genes in lower respiratory tract infections

“…The bla TEM gene (n = 29) was the most commonly detected among the β-lactamase-encoding genes, followed by bla SHV (n = 4), bla KPC (n = 2), and bla CTX−M (n = 2). KPC is a multienzyme belonging to class A carbapenemases, which are usually produced by Enterobacteriaceae, particularly K. pneumoniae and P. aeruginosa (Poirel et al, 2010;Liao et al, 2022). In the present study, K. pneumoniae, H. influenzae, and P. mirabilis were identified in the specimens with the bla KPC gene detected by TNPseq; however, the conventional culture showed no evidence of microbial growth.…”

Phenotypic Detection of Carbapenemase Production in Gram Negative Bacilli from Clinical Isolates in a Tertiary Care Hospital in Telangana

“…Nordmann et al 16 had reported this test to be 100% sensitive for detection of carbapenemase production but subsequent studies revealed a lower sensitivity of <90%. [17][18][19] Limitations of Carba NP test is that it cannot differentiate between different classes of carbapenemases, low sensitivity for detection 22,[24][25][26][27][28] It is preferable for resource limited laboratories as it is easy to do and inexpensive test. As eCIM is also performed along with mCIM for the detection of MBL's it will be helpful for differentiation between serine & metallo beta-lactamases.…”