Modified penicillin binding proteins as mechanism of resistance to antibiotics. Penicillin Binding Proteins (Transpeptidases) cross link peptidoglycan which stabilizes the cell wall - Beta-lactam antibiotics like PCN and cephalosporins bind PBPS active site and block this function - Vancomycin blocks the process by binding the terminal D-Ala, D-Ala Resistance: - Streptococcus pneumoniae will modify the PBPS so that PCN does not bind as well. THIS CAN BE OVERCOME: - Giving more antibiotic (e.g. high dose amox for an ear infection) - Switch to cephalosporin (e.g. CTX for a complicated pneumonia or pneumonia in unvaccinated) - Add vancomycin to CTX (e.g. pneumococcal meningitis) RESISTANCE: - Methicillin resistant Staphylococcus aureus makes a different transpeptidase which functions even in presence of PCNs or cephalosporins. - Vancomycin again remains active as it works at a different site. #Penicillin #Binding #Proteins #AMR #PBP #pharmacology #antibiotics #resistance
