There is line which says that the beta-lactamase resistant penicillins tend to be comparatively lipophilic molecules that do not go inside the gram -ve bacte

Krishan k jakhad Best Answer

3 generations ...Since the introduction of penicillin, β-lactam antibiotics ..BLAs have been the antimicrobial agents of choice. Unfortunately, the efficacy of these life-saving antibiotics is significantly threatened by bacterial β-lactamases. β-Lactamases are now responsible for resistance to penicillins, extended-spectrum cephalosporins, monobactams, and carbapenems. In order to overcome β-lactamase-mediated resistance, β-lactamase inhibitors (clavulanate, sulbactam, and tazobactam) were introduced into clinical practice. These inhibitors greatly enhance the efficacy of their partner β-lactams (amoxicillin, ampicillin, piperacillin, and ticarcillin) in the treatment of serious Enterobacteriaceae and penicillin-resistant staphylococcal infections. However, selective pressure from excess antibiotic use accelerated the emergence of resistance to β-lactam-β-lactamase inhibitor combinations. Furthermore, the prevalence of clinically relevant β-lactamases from other classes that are resistant to inhibition is rapidly increasing. BLA’s mechanism is based on blocking the formation of the bacterial cell wall following covalent binding to penicillin-binding proteins (PBPs), enzymes involved in the final stages of cross-linking of the peptidoglycan layer (PG) in the bacterial cell wall, both of Gram-negative and Gram-positive bacteria...Transpeptidation step mainly.