Comparison of the Carba NP test with the Rapid CARB Screen Kit for the detection of carbapenemase-producing Enterobacteriaceae and Pseudomonas aeruginosa

The purpose of this investigation was to compare the performance and cost of the Carba NP test with the Rapid CARB Screen Kit in detecting the presence of carbapenemase in Enterobacteriaceae and Pseudomonas aeruginosa. Ninety-two Enterobacteriaceae and 19 P. aeruginosa strains were used in this study. Multiplex polymerase chain reaction (PCR) was performed to determine whether these microorganisms harboured bla (VIM), bla (IMP), bla (NDM), bla (KPC) and bla (OXA-48). The Carba NP test and Rapid CARB Screen Kit were used on the strains according to the standardised protocols. The sensitivity, specificity and positive and negative predictive values of the tests were calculated. The cost of performing one test was also calculated. Forty-five Enterobacteriaceae and six P. aeruginosa were found to harbour carbapenemase-encoding genes. The Carba NP test had sensitivities of 91.1 % and 100 % for Enterobacteriaceae and P. aeruginosa, respectively. The Rapid CARB Screen Kit had sensitivities of 73.3 % and 66.7 % for Enterobacteriaceae and P. aeruginosa, respectively. The specificity of both tests was 100 %. The approximated price for performing one Carba NP test was 0.31 Euros and for CARB Screen Kit, it was 1.25 Euros. The Carba NP test performed better than the Rapid CARB Screen Kit in detecting carbapenemase production in Enterobacteriaceae and P. aeruginosa. The cost to perform both tests is reasonable.