Affinity of cefmenoxime for beta-lactamases: an analysis

Area of Science:

• Microbiology
• Pharmacology
• Biochemistry

Background:

• Beta-lactamase enzymes are a primary mechanism of bacterial resistance to beta-lactam antibiotics.
• Understanding the differential interactions of cephalosporins with various beta-lactamases is crucial for predicting antibiotic efficacy.
• Previous studies have highlighted the varying susceptibility of beta-lactamases to different cephalosporin generations.

Purpose of the Study:

• To determine the interaction profiles of cefmenoxime with specific beta-lactamase enzymes.
• To compare the affinity of cefmenoxime to beta-lactamases against other established cephalosporins, including cefotaxime, moxalactam, cefoperazone, and ceftazidime.
• To classify cephalosporins into distinct groups based on their enzymatic interaction characteristics.

Main Methods:

• Utilized on-line computerized microacidimetry to quantitatively assess the affinity of cephalosporins for beta-lactamase enzymes.
• Enzyme-substrate interactions were characterized by determining Michaelis constant (Km) values.
• Employed two distinct cephalosporinases and one penicillinase (TEM-1) as representative beta-lactamase targets.

Main Results:

• Cefmenoxime, cefotaxime, and moxalactam demonstrated high affinity for cephalosporinases and very poor affinity for penicillinase.
• Ceftazidime showed moderate affinity for cephalosporinases and poor affinity for penicillinase.
• Cefoperazone exhibited poor affinity for all tested enzymes and was the only cephalosporin to undergo significant hydrolysis by penicillinase (TEM-1).

Conclusions:

• Cefmenoxime possesses a favorable interaction profile with cephalosporinases, suggesting potential efficacy against bacteria producing these enzymes.
• The study successfully classified cephalosporins into three groups based on their differential affinities for cephalosporinases and penicillinases.
• These findings provide valuable insights into the structure-activity relationships of cephalosporins concerning beta-lactamase stability and resistance.