EDTA-modified carbapenem inactivation method (eCIM) for detecting IMP Metallo-β-lactamase–producing Pseudomonas aeruginosa : an assessment of increasing EDTA concentrations

BMC Microbiology

article

Lasko, Maxwell J.¹  Gill, Christian M.¹  Asempa, Tomefa E.¹  Nicolau, David P.¹ 

[1] Center for Anti-Infective Research and Development, Hartford Hospital;Division of Infectious Diseases, Hartford Hospital

关键词: Carbapenemase;    Resistance;    Zinc-dependent;    Metallo-β-lactamase;    Pseudomonas aeruginosa;   

DOI  :  10.1186/s12866-020-01902-8

学科分类：放射科、核医学、医学影像

来源: BioMed Central

【 摘 要 】

Prompt identification of carbapenemase-harboring organisms is valuable in informing therapeutic and infection-control measures. The modified carbapenem inactivation method (mCIM) and EDTA-modified carbapenem inactivation method (eCIM) are inexpensive and easy to interpret phenotypic tests endorsed by the Clinical and Laboratory Standards Institute (CLSI) for the detection of carbapenemase-harboring Enterobacterales. Only mCIM is endorsed by CLSI for detecting carbapenemase-harboring Pseudomonas aeruginosa. eCIM’s ability to delineate serine and metallo-β-lactamases (MBL) could be advantageous in areas prevalent with carbapenemase-harboring P. aeruginosa. A recent assessment of mCIM/eCIM on MBL-harboring P. aeruginosa demonstrated high eCIM sensitivity for NDMs and VIMs but not for IMP-producers. Therefore, this study aimed to determine whether increasing EDTA concentrations would enhance eCIM sensitivity for a collection of IMP-harboring P. aeruginosa isolates. Twenty-six IMP-harboring P. aeruginosa isolates were utilized. For test validation, additional P. aeruginosa isolates harboring NDM (n = 3), VIM (n = 3), KPC (n = 8), wild-type (n = 1), and Enterobacterales isolates harboring IMP (n = 6) and NDM (n = 1) were assessed. The mCIM test was conducted as outlined by CLSI. Simultaneously, the eCIM test was performed with the standard 5 mM EDTA concentration and doubling EDTA concentrations: 10 mM, 20 mM, and 40 mM. Concentration-dependent improvement was observed among the IMP-harboring P. aeruginosa with eCIM sensitivities at 0, 31, 85, and 100% respectively. Remaining Enterobacterales and P. aeruginosa responded concordantly with their genotype at the standard 5 mM eCIM concentration, with doubling EDTA concentrations providing no greater sensitivity. Combination of mCIM and an eCIM with a 40 mM EDTA concentration appropriately capture IMP-harboring P. aeruginosa without sacrificing test utility for other carbapenemase-harboring isolates.

【 授权许可】

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