Porin Loss/Mutation and Efflux Pump Overexpression - Mechanism of Antimicrobial Resistance in Gram-Negative Bacteria

Porins let drugs in, efflux pumps kick them out — alone, neither does much damage. Real resistance in Gram-negatives needs porin loss, efflux overexpression, and β-lactamases working together. Plus a surprising twist about Pseudomonas and ertapenem that challenges conventional teaching.