carbapenemaser

Carbapenemase refers to an enzyme produced by certain bacteria that hydrolyzes carbapenems, a class of last-resort beta-lactam antibiotics. Carbapenemases are beta-lactamases capable of inactivating carbapenems and often other beta-lactams, contributing to multidrug resistance. Most carbapenemases fall into Ambler classes A, B, or D. Class B enzymes are metallo-beta-lactamases (MBLs), which require zinc for activity and include NDM, VIM, and IMP. Class A includes enzymes such as KPC and certain GES variants, while class D includes OXA-48-like enzymes. These enzymes are frequently encoded on mobile genetic elements like plasmids and transposons, enabling rapid spread among Gram-negative bacteria such as Enterobacterales, Pseudomonas aeruginosa, and Acinetobacter baumannii.

Impact and epidemiology: infections caused by carbapenemase-producing organisms are difficult to treat and are associated with higher morbidity and mortality. They are a global public health concern, with regional differences in enzyme prevalence and rapid dissemination through horizontal gene transfer and clonal spread.

Detection: laboratory detection combines phenotypic tests (for example, Carba NP, CIM, or other inhibitor-based assays) with molecular methods (PCR, sequencing) to identify specific carbapenemase genes. Accurate detection informs treatment decisions and infection-control measures.

Treatment considerations: therapeutic options depend on the enzyme class. Serine carbapenemases (for example, KPC, OXA-48-like) may be inhibited by certain beta-lactamase inhibitors, enabling combinations such as ceftazidime-avibactam or meropenem-vaborbactam to be effective against many producers. Metallo-beta-lactamases are less susceptible to these inhibitors, sometimes requiring alternative strategies such as aztreonam in combination with a beta-lactamase inhibitor. Cefiderocol provides activity against many carbapenemase producers, though resistance can develop. Irrespective of therapy, infection control and antimicrobial stewardship are essential to limit spread.