Is This the Carbapenemase Test We’ve Been Waiting for? A Multicenter Evaluation of the Modified Carbapenem Inactivation Method

July 26, 2017 at 9:25 am

Journal of Clinical Microbiology August 2017 V.55 N.8 P.2309-2312

Susan M. Butler-Wu and April N. Abbott

aDepartment of Pathology and Laboratory Medicine, Keck School of Medicine, University of Southern California, Los Angeles, California, USA

bDepartment of Pathology, Deaconess Health System, Evansville, Indiana, USA


A plethora of phenotypic methods exist for the detection of carbapenemases; however, clinical laboratories have struggled for years with accurate, objective phenotypic detection of carbapenemase activity in Enterobacteriaceae. In this issue of the Journal of Clinical Microbiology, V. M. Pierce et al. (J Clin Microbiol 55:2321–2333, 2017, report on a multicenter evaluation of the modified carbapenem inactivation method (mCIM). The high sensitivity, specificity, reproducibility, and ease of interpretation associated with the mCIM for Enterobacteriaceae will likely lead to its adoption by clinical laboratories.



Journal of Clinical Microbiology August 2017 V.55 N.8 P.2321-2333

Modified Carbapenem Inactivation Method for Phenotypic Detection of Carbapenemase Production among Enterobacteriaceae

Virginia M. Pierce, Patricia J. Simner, David R. Lonsway, Darcie E. Roe-Carpenter, J. Kristie Johnson, William B. Brasso, April M. Bobenchik, Zabrina C. Lockett, Angella Charnot-Katsikas, Mary Jane Ferraro, Richard B. Thomson Jr., Stephen G. Jenkins, Brandi M. Limbago, and Sanchita Das

aDepartment of Pathology, Massachusetts General Hospital, Boston, Massachusetts, USA

bDepartment of Pathology, Johns Hopkins Medical Institutions, Baltimore, Maryland, USA

cDivision of Healthcare Quality Promotion, Centers for Disease Control and Prevention, Atlanta, Georgia, USA

dBeckman Coulter Diagnostics, Inc., West Sacramento, California, USA

eDepartment of Pathology, University of Maryland School of Medicine, Baltimore, Maryland, USA

fBD Life Sciences–Diagnostic Systems, Sparks, Maryland, USA

gDepartment of Pathology and Laboratory Medicine, Lifespan Academic Medical Center, Providence, Rhode Island, USA

hDepartment of Pathology, University of Chicago Medical Center, Chicago, Illinois, USA

iDepartment of Pathology, NorthShore University HealthSystem, Evanston, Illinois, USA

jDepartment of Pathology and Laboratory Medicine, Weill-Cornell Medical College, New York, New York, USA

The ability of clinical microbiology laboratories to reliably detect carbapenemase-producing carbapenem-resistant Enterobacteriaceae (CP-CRE) is an important element of the effort to prevent and contain the spread of these pathogens and an integral part of antimicrobial stewardship. All existing methods have limitations. A new, straightforward, inexpensive, and specific phenotypic method for the detection of carbapenemase production, the carbapenem inactivation method (CIM), was recently described. Here we describe a two-stage evaluation of a modified carbapenem inactivation method (mCIM), in which tryptic soy broth was substituted for water during the inactivation step and the length of this incubation was extended. A validation study was performed in a single clinical laboratory to determine the accuracy of the mCIM, followed by a nine-laboratory study to verify the reproducibility of these results and define the zone size cutoff that best discriminated between CP-CRE and members of the family Enterobacteriaceae that do not produce carbapenemases. Bacterial isolates previously characterized through whole-genome sequencing or targeted PCR as to the presence or absence of carbapenemase genes were tested for carbapenemase production using the mCIM; isolates with Ambler class A, B, and D carbapenemases, non-CP-CRE isolates, and carbapenem-susceptible isolates were included. The sensitivity of the mCIM observed in the validation study was 99% (95% confidence interval [95% CI], 93% to 100%), and the specificity was 100% (95% CI, 82% to 100%). In the second stage of the study, the range of sensitivities observed across nine laboratories was 93% to 100%, with a mean of 97%; the range of specificities was 97% to 100%, with a mean of 99%. The mCIM was easy to perform and interpret for Enterobacteriaceae, with results in less than 24 h and excellent reproducibility across laboratories.




Entry filed under: Antimicrobianos, Bacterias, Bacteriemias, Epidemiología, Health Care-Associated Infections, Infecciones emergentes, Infecciones nosocomiales, Infecciones sitio quirurgico, Metodos diagnosticos, Resistencia bacteriana, Sepsis, Update.

False-Positive Rapid Malaria Antigen Test Result in a Returned Traveler Molecular Diagnosis of Orthopedic-Device-Related Infection Directly from Sonication Fluid by Metagenomic Sequencing


July 2017
« Jun   Aug »

Most Recent Posts

%d bloggers like this: