الفهرس 
CarbapenemsOnly 14 pages are availabe for public view
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Abstract
The increasing resistance to carbapenems, the last resort antibiotic against multi-drug resistant bacteria, is a worldwide clinical concern. Resistance is mainly due to the carbapenem hydrolysing enzymes, carbapenemases, which hydrolyse most β-lactams. Carbapenemases are found on diverse mobile genetic elements, including plasmids, transposons and integrons that may carry multiple resistance genes, leading to resistance to many antibiotic classes, such as aminoglycosides, quinolones, tetracyclines, trimethoprim, sulphonamides and phenicols.
Carbapenemases have been classified molecularly into two groups based on their active sites: MBL (class B), and serine-based (classes A and D) carbapenemases. Also, carbapenem resistance may be due to the hyper-production of ESBLs or AmpC beta-lactamases coupled with outer membrane impermeability due to efflux pump up-regulation and/or porin loss or mutation.
Because of the complexity and diversity of carbapenem resistance mechanisms, particularly carbapenemase- mediated resistance, rapid and accurate detection is necessary to inform appropriate therapy.
Blue Carba test is a biochemical test with high sensitivity and specificity, and faster turnaround times than culture based methods. They were developed for the detection of carbapenemase producers in Enterobacteriaceae, and A. baumannii.
The aim of this work is to detect the ability of Blue-Carba test for rapid identification of carbapenemase producing organisms (Enterobacteriaceae and Acinetobacter).
During this study, fifty carbapenem-resistant gram-negative isolates, collected from different clinical samples submitted for routine culture and sensitivity in Central Microbiology Laboratory Ain Shams University Hospitals, were included. They were subjected to MHT, Blue Carba tests, subcultured on chromID SMART media.
47/50 (94%) isolates were positive for carbapenemase production by MHT.
48/50 (96%) isolates were positive for carbapenemase production by Blue Carba tests. All the 50 isolates (100%) were positive by chromID SMART.
Blue Carba test showed sensitivity of 100%, and specificity 100% compared to PCR in tested isolates.
Modified Hodge test showed sensitivity, 93.8% compared to PCR in tested isolates.
ChromID SMART test showed sensitivity of 100% compared to PCR.
In conclusion, Blue Carba test is inexpensive, rapid (2hrs), sensitive and specific methods for detection of carbapenemase production from bacterial colonies grown on culture media.
The Modified Hodge test is simple and inexpensive to perform. Also, demonstrates good sensitivity for many carbapenemases, but experienced low sensitivity for some carbapenemases as NDM-1.
ChromID SMART is an easy screening method for the detection of carbapenem resistance, however it lacks specificity in detection of carbapenemase production.