Multicenter evaluation of the RAPIDEC® CARBA NP test for rapid screening of carbapenemase-producing Enterobacteriaceae and Gram-negative nonfermenters from clinical specimens

- RAPIDEC® CARBA NP could detect carbapenemase producers from positive blood cultures, after 6 h of subculture.
- The test showed low sensitivity with carbapenemase-producing A. baumannii.
- Excluding A. baumannii the test showed high sensitivity (100%) and specificity (94%).

The rapid diagnosis of carbapenemase-producing (CP) bacteria is essential for the management of therapy and infection control. In this study, RAPIDEC® CARBA NP (RCNP) was evaluated for the rapid screening of CP Enterobacteriaceae, Acinetobacter baumannii complex, and Pseudomonas aeruginosa from clinical specimens collected at five Italian hospitals. Firstly, each site tested 20 well-characterized strains in a blinded fashion. Secondly, each center prospectively tested 25 isolates from blood cultures processed with a rapid workflow (6 h after subculture) and 25 isolates from other specimens processed after an overnight culture. The presence of carbapenemases was confirmed by multiplex real-timePCRs targeting carbapenemase genes. RCNP presented an overall sensitivity, specificity, positive predictive value, and negative predictive value of 70%, 94%, 82%, and 89%, respectively, with a higher performance in detection of CP Enterobacteriaceae and a poorer performance in detection of CP A. baumannii complex. With isolates from blood cultures, RCNP could significantly reduce the time required for identification of CP Enterobacteriaceae (less than 9 h since the positivization of blood cultures).