Evaluation of Two Phenotypic Screening Tests for Carbapenemase-Producing Enterobacteriaceae

Abstract

We evaluated the performance of two rapid tests for detection of carbapenemase-producing Enterobacteriaceae (CPE) strains. The sensitivities and the specificities were 97.6% and 94.4% for the Rapid CARB Screen and 98.8% and 93.1% for the KPC/MBL & OXA-48 Confirm tests, providing the usefulness of these tools for screening CPE in microbiology wards.T he global dissemination of extremely drug-resistant (XDR) Gram-negative bacilli with acquired carbapenemase genes is a major public health concern (1, 2). Vigilant surveillance and rapid and reliable identification of these strains by personnel in the clinical microbiology laboratory are essential to effective infection control (screening of patients who come from a foreign country and were hospitalized in this country in the previous year, screening of contact patients, etc.) (3, 4). Mass spectrometry and molecular typing are used to detect enzymatic resistance to carbapenems and eliminate impermeability mechanisms (5). However, these techniques require specific equipment and substantial expertise and, thus, cannot be implemented in all laboratories. Moreover, PCR-based techniques have the limitation of not detecting new enzymes (6). Recently, new phenotype-based methods have become more accessible. They have been described for the identification of carbapenemase-producing Enterobacteriaceae (CPE) and include the modified Hodge test (MHT) (7), biochemical tests detecting carbapenemase hydrolytic activity (8), carbapenemase inhibitor-based tests (9, 10), and high-level temocillin resistance for OXA-48-like carbapenemase, for which no specific inhibitor is available (11). This work aimed to evaluate two screening methods recently commercialized for the detection of CPE in clinical microbiology laboratories: the Rapid CARB Screen (RCS) kit and the KPC/MBL & OXA-48 Confirm (KMOC) kit (Rosco Diagnostica A/S, Taastrup, Denmark).A panel of 155 clinical and ATCC strains of various enterobacterial species belonging to a collection of our regional multidrugresistant Gram-negative Bacilli Reference Lab was tested (12-14) ( Table 1). Eighty-three strains harboring known carbapenemaseencoding genes were included in this panel. All these isolates were typed by the Check-MDR CT102 microarray (Check-Points, Netherlands), and the presence of carbapenemase genes was confirmed by specific PCR and sequence analysis (15). Seventy-two carbapenemase-negative isolates were also included: 61 carbapenem resistant due to overexpression of chromosomal AmpC or expression of plasmid-mediated AmpC and/or extended-spectrum beta-lactamases coupled to impermeability and 11 carbapenem susceptible. In all isolates, plasmid-mediated AmpC were identified by multiplex PCR (16).Carbapenem MICs were determined by Etest (bioMérieux, Marcy l'Etoile), and the results were interpreted using the Société Française de Microbiologie (SFM)/EUCAST guidelines (http: //www.sfm-microbiologie.org). The RCS and KMOC tests were performed on strains grown on Mueller-Hinton agar plates following the manufacturer's recommend...

Spread of OXA-48 and NDM-1-Producing Klebsiella pneumoniae ST48 and ST101 in Chicken Meat in Western Algeria

“…Further confirmation of carbapenemase producers was investigated using the KPC/MBL and OXA-48 Confirm Kit (Rosco Diagnostica A/S, Taastrup, Denmark) according to the manufacturer's instructions. 21 (www.eucast.org). Ertapenem, imipenem, meropenem, and colistin minimal inhibition concentrations were determined by Etest method (bioMérieux) and microbroth dilution (Umic Ò ; Biocentric, Bandol, France).…”

Evaluation of modified carbapenem inactivation method for suspected carbapenemase among Enterobacteriaceae clinical isolates

“…For this purpose, rapid and reliable identification of carbapenemase producers in the clinical microbiology laboratory is urgently needed to affect infection treatment. Currently, although several commercial tests are available for detection of carbapenem resistance including phenotypic or genotypic tests, none is ideal for all possible carbapenemase genes [ 4 ]. In 2017, modified carbapenem inactivation method (mCIM) testing was recommended by Clinical and Laboratory Standard Institute (CLSI) for detection of carbapenemase among Enterobacteriaceae clinical isolates [ 5 ].…”

Clinical and laboratory considerations for the rapid detection of carbapenem-resistant Enterobacteriaceae

“…Performance of these commercial systems appears to be on par with the manual method. 32,34,35 Recently, Bogaerts and colleagues described the Bogaerts-Yunus-Glupcynski (BYG) Carba test, which is based on the same principles as the Carba NP, but uses an electrochemical method to detect imipenem hydrolysis. The BYG detects variations of conductivity in a polyaniline coated electrode that are imparted by the pH shift and redox activity that occurs during imipenem hydrolysis.…”