Abstract
The spread of carbapenemase-producing Enterobacteriaceae (CPE) is an increasing global public health concern. The development of simple and reliable methods for CPE detection is required in the clinical setting. This study aimed to establish a dual-wavelength measurement method using an ultraviolet–visible spectrophotometer to rapidly quantify imipenem hydrolysis in bacterial cell suspensions. The hydrolytic activities of 148 strains including various CPE strains (Escherichia coli, Klebsiella pneumoniae, Enterobacter cloacae, and Enterobacter aerogenes containing the blaIMP, blaKPC, blaNDM, blaOXA, and blaVIM genes) were measured and analysed. A cut-off value was obtained for differentiation between CPE and non-CPE strains, and the method had high sensitivity (100%) and specificity (100%) within 60 min. Our system has potential clinical applications in detecting CPE.
Highlights
Carbapenemase-producing Enterobacteriaceae (CPE) have been increasingly reported worldwide in recent years; they frequently display multi-drug resistance and cause severe infections in immunocompromised patients, with limited treatment options
Non-nucleic acid-based tests commonly harness the hydrolytic activity of carbapenemases
Enzymatic hydrolysis of imipenem by carbapenemase-producing Enterobacteriaceae (CPE) and non-CPE strains was examined by measuring the absorbance of bacterial cell suspensions
Summary
Carbapenemase-producing Enterobacteriaceae (CPE) have been increasingly reported worldwide in recent years; they frequently display multi-drug resistance and cause severe infections in immunocompromised patients, with limited treatment options. Nucleic acid-based tests include the polymerase chain reaction (PCR) and sequencing and are considered one of the most reliable methods for confirming the presence of CPE. Non-nucleic acid-based tests commonly harness the hydrolytic activity of carbapenemases. The Carba NP test depends on imipenem hydrolysis by a carbapenemase and a subsequent change in pH and colour of Phenol Red in the reaction mixture. The colour change is discerned with the naked eye within 120 min, and the method is efficient with KPC-type carbapenemase and metallo-β-lactamase producers. The Carba NP test has shown lower detection sensitivity with OXA-type carbapenemase producers[6,7,9]. This method has shown high sensitivity and specificity for detecting CPE, carbapenemase extraction from bacterial cells is somewhat time consuming and is not suitable for rapid detection
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