Phenotypic and genotypic detection of metallo-B-lactamases producing : A study done in two university hospitals

Authors

Abstract

Background
Metallo-beta-lactamase (MBL) producing has emerged as a threat to hospital-infection control due to its multidrug resistance, but the laboratory detection of these strains is not well defined.
Objectives
Screening for MBL production from isolates from different clinical specimens using different phenotypic and genotyping techniques. In addition, we aim to apply a PCR test for genetic confirmation of MBL producers.
Patients and methods
We used EDTA-disk screen test and molecular diagnostic assay for the detection of MBL-producing isolated from different clinical specimens collected in Kasr Alainy and Fayoum University Hospitals. Using Clinical and Laboratory Standards Institute-disk methodology, inhibition-zone diameters were determined in tests with imipenem (IPM) and meropenem disks alone and in combination with 750 μg of EDTA. This test was compared with the MBL E-test. Detection for MBL-production genes ( and ) was done using PCR.
Results
Of the 50 clinical strains of IPM nonsusceptible , 32/50 (64.0%) were MBL positive using disk-diffusion methods, 26/50 (52.0%) were positive for MBL by E-test, while 17/50 (34.0%) were positive for MBL genes: 17/50 (34.0%) for and 0/50 (0%) for . The EDTA disk-screen test using IPM showed 100% sensitivity and 54.5% specificity for detecting MBLs in clinical strains. While E-test showed 100% sensitivity and 69.7% specificity.
Conclusion
The EDTA disk-screen test was simple to perform and to interpret and can easily be introduced into the workflow of a clinical laboratory. We recommend that all IPM nonsusceptible isolates be routinely screened for MBL production using the EDTA disk-screen test and PCR confirmation be performed at a regional laboratory.

Keywords

Files

Share

How to cite

Statistics