A review of phenotypic carbapenemase detection methods

Carbapenems are broad-spectrum antibiotics used to treat multidrug-resistant infections caused by Gram-negative, Gram-positive, and anaerobic bacteria. However, the overuse of these antibiotics has led to the rise of carbapenem-resistant bacteria (CRB), which present significant treatment challenges. Carbapenem resistance is primarily mediated by the production of carbapenemase enzymes, which hydrolyze carbapenems and are often encoded by plasmids, facilitating horizontal gene transfer. Rapid detection of carbapenemase-producing organisms is crucial for effective antimicrobial stewardship and preventing the spread of resistance. Phenotypic methods for detecting carbapenemases include disk diffusion, minimum inhibitory concentration (MIC) methods, gradient diffusion, automated systems, and chromogenic media. More advanced techniques, such as the Carba NP test and immunochromatographic assays, provide rapid identification of resistance profiles, while spectrophotometric analysis detects enzymatic hydrolysis. The choice of method depends on sensitivity, specificity, and clinical context. Early and accurate detection allows for timely adjustments to treatment, optimizing patient outcomes and limiting the misuse of broad-spectrum antibiotics.