betalactamasen

Beta-lactamases are enzymes produced by certain bacteria that confer resistance to beta-lactam antibiotics, including penicillins, cephalosporins, and carbapenems. These enzymes work by breaking the characteristic beta-lactam ring structure of these antibiotics, rendering them ineffective against bacterial infections.

The mechanism of action involves the hydrolysis of the amide bond within the beta-lactam ring, which is essential for the antibiotic's antibacterial activity. Beta-lactamases are classified into four main molecular classes (A, B, C, and D) based on their amino acid sequences and structural characteristics. Class A includes TEM and SHV enzymes, while class B encompasses metallo-beta-lactamases that require zinc ions for activity. Class C contains AmpC enzymes, and class D includes oxacillinases.

Bacteria produce beta-lactamases either chromosomally or through plasmid-mediated genes that can be transferred between different bacterial species. This horizontal gene transfer contributes significantly to the rapid spread of antibiotic resistance among pathogenic bacteria. Clinically relevant producers include Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Staphylococcus aureus.

The emergence and spread of extended-spectrum beta-lactamases (ESBLs) and carbapenemases pose significant challenges to modern medicine. ESBLs can hydrolyze extended-spectrum cephalosporins and monobactams, while carbapenemases inactivate even the most potent beta-lactam antibiotics. Laboratory detection of beta-lactamase production is crucial for appropriate antibiotic selection and infection control measures.

To combat beta-lactamase-mediated resistance, beta-lactamase inhibitors such as clavulanic acid, sulbactam, and tazobactam are commonly combined with beta-lactam antibiotics. These inhibitors protect the antibiotic from enzymatic degradation, restoring or enhancing therapeutic efficacy against resistant bacterial strains.