Bacteria develop ability to hydrolyze these drugs using β lactamase confers resistance to penicillin e.g. E. coli, Staph epidermidis, Pseudomonas aeruginosa, Klebsiella pneumoniae add β lactamase inhibitor e.g. clavulanic acid in amoxicillin-clavulanate (Augmentin) Genetic mutation of mecA carried by Staphylococcal cassette chromosome (SCCmec) mobile genetic unit a bacterial gene encoding a penicillin-binding protein (PBP2a). PBP2a has reduced affinity for antibiotics confers resistance to methicillin, oxacillin, nafcillin e.g. MRSA SCCmec type IV has less genetic elements and is specific to CA-MRSA, making CA-MRSA less multi-drug resistant Altered cell wall permeability confers resistance to tetracyclines, quinolones, trimethoprim and β lactam antibiotics Creation of biofilm barrier provides an environment where offending bacteria can multiply safe from the hoste immune system Salmonella Staph epidermidis Active efflux pumps confers res...
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