Development and Application of a Pragmatic Algorithm to Guide Definitive Carbapenemase Testing to Identify Carbapenemase-Producing <i>Pseudomonas aeruginosa</i>

• Main Authors: Christian M. Gill (Author), Tomefa E. Asempa (Author), David P. Nicolau (Author)
• Format: Book
• Published: MDPI AG, 2020-10-01T00:00:00Z.
• Subjects: article
• Online Access: Connect to this object online.

Summary

A minimum inhibitory concentration (MIC) derived algorithm, predictive of carbapenemase production, was developed using a challenge set (<i>n</i> = 92) of <i>Pseudomonas aeruginosa</i> (PA), including carbapenemase-producing (CP), cephalosporinase and/or efflux/porin mutation, and wild-type isolates. Broth microdilution MICs to clinically relevant anti-pseudomonal agents were utilized. The algorithm was applied to 1209 clinical PA isolates from a US surveillance program. Confirmatory genotypic (Xpert^® Carba-R assay) and phenotypic (mCIM/eCIM) testing for carbapenemases was conducted on algorithm-derived isolates. With the algorithm, carbapenem resistance alone resulted in poor specificity to identify CP-PA (54%) within the challenge set of isolates. Inclusion of cefepime, ceftazidime, and piperacillin/tazobactam non-susceptibility resulted in a specificity of 66%. Ceftolozane/tazobactam resistance further improved specificity (89%). Of the 1209 isolates, 116 met criteria (carbapenem-resistant and non-susceptibility to cefepime, ceftazidime, and piperacillin/tazobactam) for confirmatory testing. Carba-R and mCIM/eCIM identified five (all <i>bla</i>_VIM-positive) and seven carbapenemase-producing isolates, respectively. This MIC algorithm combined with genotypic/phenotypic carbapenemase testing is a pragmatic and streamlined approach to identify CP-PA.

Item Description

10.3390/antibiotics9110738
2079-6382