Program Schedule

Comparative Effectiveness of the Three Most Popular Automated Identification and Susceptibility Platforms for Testing Multidrug-resistant and Carbapenemase-producing Organisms

Session: Poster Abstract Session: Diagnostic Microbiology: Bacterial Infections
Saturday, October 11, 2014
Room: The Pennsylvania Convention Center: IDExpo Hall BC
Background: Although several publications have compared the performance of the  Vitek-2 (Biomerieux), Phoenix (Becton Dickinson), and the Microscan Walkaway (Siemens), most included a smaller number of number of drug-organism combinations, and  none reported in their methodology a true tri-partite (same day/same plate) comparison. Such a comparison allows simultaneous inoculation from one culture to minimize operator and culture growth biases.

Methods: The Multidrug-resistant organism Repository and Surveillance Network (MRSN) circumvented these biases and conducted the first reported tri-partite comparison study.  Analysis included >20,000 drug-organism combinations of Acinetobacter baumannii, Klebsiella pneumoniae, Pseudomonas aeruginosa, Escherichia coli, and methicillin-resistant Staphylococcus aureus from 2003-2013.

Results: We found all machines performed to the manufacturers’ performance standards.  However, the Phoenix produced the least number of total susceptibility errors, and the Vitek-2 was the most reliable source for organism identification. Furthermore, susceptibility error rates were dependent on the drug-organism combination, with the most errors occurring with E. coli and K. pneumoniaeand select carbapenems or cephalosporins, particularly cefepime. Microscan had the greatest number of susceptibility errors for testing MRSA.

Conclusion: The Phoenix offers the most reliable antibiotic susceptibility testing results, while the Vitek-2 correctly identifies the organism more often than the other machines. The cost associated with sample processing is slightly higher on the Phoenix platform relative to the Vitek-2. Microscan costs are approximately half of the other two platforms.  In addition to being the first same day/same plate comparison, this comparison also includes the largest number of antibiotic-organism combinations.

Lindsey Nielsen, PhD1, Robert Clifford, PhD1, Yoon Kwak, MS1, Caroline Argyros1, Ronald Rabinowitz, MD2, Paige Waterman, MD1 and Emil Lesho, DO1, (1)Walter Reed Army Institute of Research, Silver Spring, MD, (2)University of Maryland Shock Trauma Center, Baltimore, MD


L. Nielsen, None

R. Clifford, None

Y. Kwak, None

C. Argyros, None

R. Rabinowitz, None

P. Waterman, None

E. Lesho, None

Findings in the abstracts are embargoed until 12:01 a.m. EDT, Oct. 8th with the exception of research findings presented at the IDWeek press conferences.

Sponsoring Societies:

© 2014, All Rights Reserved.

Follow IDWeek