Solving staphylococcal resistance to beta-lactams.

Class resistance to beta-lactam antibiotics in Gram-positive bacteria is mediated by structural changes in transpeptidase penicillin-binding proteins. These structural changes render a complex series of interactions between antibiotic and protein that are energetically unfavorable, such that the active site is inactivated not at all or too slowly to prevent cell-wall synthesis and bacterial growth. Determination of the crystal structure of the low-affinity penicillin-binding protein PBP2a, which mediates beta-lactam antibiotic resistance in staphylococci, has identified the molecular structures and interactions that are responsible for resistance. This information could be useful for designing beta-lactams to overcome these structural impediments, as well as resistance.