Multicenter evaluation of the modified carbapenem inactivation method and the carba NP for detection of carbapenemase-producing pseudomonas aeruginosa and acinetobacter baumannii

Patricia Simner, J. Kristie Johnson, William B. Brasso, Karen Anderson, David R. Lonsway, Virginia M. Pierce, April M. Bobenchik, Zabrina C. Lockett, Angella Charnot-Katsikas, Lars F. Westblade, Brian B. Yoo, Stephen G. Jenkins, Brandi M. Limbago, Sanchita Das, Darcie E. Roe-Carpenter

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Abstract

The purpose of this study was to develop the modified carbapenem inactivation method (mCIM) for the detection of carbapenemase-producing Pseudomonas aeruginosa (CP-PA) and carbapenemase-producing Acinetobacter baumannii (CP-AB) and perform a multicenter evaluation of the mCIM and Carba NP tests for these nonfermenters. Thirty P. aeruginosa and 30 A. baumannii isolates previously characterized by whole-genome sequencing from the CDC-FDA Antibiotic Resistance Isolate Bank were evaluated, including CP isolates (Ambler class A, B, and D), non-carbapenemase-producing (non-CP) carbapenem-resistant isolates, and carbapenem-susceptible isolates. Initial comparison of a 1-l versus 10-l loop inoculum for the mCIM was performed by two testing sites and showed that 10 l was required for reliable detection of carbapenemase production among P. aeruginosa and A. baumannii. Ten testing sites then evaluated the mCIM using a 10-l loop inoculum. Overall, the mean sensitivity and specificity of the mCIM for detection of CP-PA across all 10 sites were 98.0% (95% confidence interval [CI], 94.3 to 99.6; range, 86.7 to 100) and 95% (95% CI, 89.8 to 97.7; range, 93.3 to 100), whereas the mean sensitivity and specificity among CP-AB were 79.8% (95% CI, 74.0 to 84.9; range, 36.3 to 95.7) and 52.9% (95% CI, 40.6 to 64.9; range, 28.6 to 100), respectively. At three sites that evaluated the performance of the Carba NP test using the same set of isolates, the mean sensitivity and specificity of the Carba NP test were 97.8% (95% CI, 88.2 to 99.9; range, 93.3 to 100) and 97.8% (95% CI, 88.2 to 99.9; range, 93.3 to 100) for P. aeruginosa and 18.8% (95% CI, 10.4 to 30.1; range, 8.7 to 26.1) and 100% (95% CI, 83.9 to 100; range, 100) for A. baumannii. Overall, we found both the mCIM and the Carba NP test to be accurate for detection of carbapenemase production among P. aeruginosa isolates and less reliable for use with A. baumannii isolates.

Original languageEnglish (US)
Article numbere01369
JournalJournal of Clinical Microbiology
Volume56
Issue number1
DOIs
StatePublished - Jan 1 2018

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Keywords

  • Acinetobacter baumannii
  • Carba NP
  • Carbapenem resistance
  • Carbapenemase
  • MCIM
  • Pseudomonas aeruginosa

ASJC Scopus subject areas

  • Microbiology (medical)

Cite this

Simner, P., Kristie Johnson, J., Brasso, W. B., Anderson, K., Lonsway, D. R., Pierce, V. M., Bobenchik, A. M., Lockett, Z. C., Charnot-Katsikas, A., Westblade, L. F., Yoo, B. B., Jenkins, S. G., Limbago, B. M., Das, S., & Roe-Carpenter, D. E. (2018). Multicenter evaluation of the modified carbapenem inactivation method and the carba NP for detection of carbapenemase-producing pseudomonas aeruginosa and acinetobacter baumannii. Journal of Clinical Microbiology, 56(1), [e01369]. https://doi.org/10.1128/JCM.01369-17