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

Abstract

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 (6h 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 9h since the positivization of blood cultures).

Ceftazidime-Avibactam Resistance Associated with Increased bla KPC-3 Gene Copy Number Mediated by pKpQIL Plasmid Derivatives in Sequence Type 258 Klebsiella pneumoniae

“…Transformants were selected on Mueller-Hinton agar (MHA) supplemented with 8 g/ml ceftazidime. Transfer of bla KPC gene was always confirmed by real-time PCR (31). Conjugal transfer experiments were carried out as previously described, using K. pneumoniae KP-8788 as donor and both E. coli MKD-135 (rifampin resistant) and E. coli J53 (sodium azide resistant) as recipients (32).…”

Rapid Detection of Carbapenemase Production Directly from Blood Culture by Colorimetric Methods: Evaluation in a Routine Microbiology Laboratory

“…Other techniques for the detection of carbapenemase production directly from blood culture have been published (12); however, they are usually based on molecular detection. In fact, only a few studies also assessed the use of colorimetric assays directly from blood cultures in a routine laboratory; however, these studies used different protocols, which are either more expensive or longer than the one we have used in our study (13,14).…”

Rapid phenotypic methods to improve the diagnosis of bacterial bloodstream infections: meeting the challenge to reduce the time to result

“…The same approach performed with Vitek dramatically reduces the time to result to <14 h with a similar performance to standard AST [63] (Table 3). Colorimetric tests and MALDI-TOF MS-based approaches for detecting antibiotic degradation can be carried out on young colonies, thereby bypassing the extraction step required when performed directly from BCs [38,60,61].…”