engleski

A variant carbapenem inactivation method (CIM) for Aci-netobacter baumannii group with hortened time- to-result: rCIM-A

Carbapenem-resistant Acinetobacter baumanii Group organisms (CRAB) are challenging because choice between targeted, new antibiotic drug options should be guided by a timely identification of resistance- mechanisms. In CRAB acquired class-D carbapenemases (CHDLs) being most active against ertapenem and imipenem are dominating. If PCR- methods are not first-choice, phenotypic methods have to be implemented. Carbapenemase inactivation method (CIM) using meropenem-hydrolysis has been promising, however was hampered by poor performance or overly long time-to-result. We developed a rapid method (rCIM-A) of good performance using ertapenem-, imipenem-, and meropenem-disks, 2-hours permeabilization and incubation with the test-strain in tryptic soy- broth and read-out of residual carbapenem activity after 6, and optionally 16-18 hours. Using clinical isolates and type-strains of Acinetobacter (n = 67) not harboring car- bapenemases (n = 28) or harboring genes of acquired carbapenemases (n = 39), sensitivity of detection was 97.4% with the imipenem-disk after 6 hours at specificity 92.9%. If the inhibition zone around the ertapenem-disk at 6 hours was 6 mm or ≤26 mm for ertapenem or ≤25.5 mm for meropenem, specificity was 100%. We newly describe ”carryover-microsatellites” as positive CIM-result occurance. Because of high negative-predictive- value, the rCIM-A seems particularly appropriate in areas of lower CRAB- frequencies.

: carbapenem-resistant Acinetobacter baumannii ; novel antibacterial agents ; antimicrobial resistance ; molecular mechanisms ; phenotypic carbapenemase detection ; rapid diagnostic test ; nosocomial infection ; infection prevention and control ; OXA-type carbapenemases ; carbapenem inactivation method

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