The threat of antibiotic resistance in Gram-negative pathogenic bacteria: β-lactams in peril!

β-Lactam antibiotics are the cornerstone of our antibiotic armamentarium. By inhibiting bacterial cell wall synthesis, they are highly effective against Gram-positive and Gram-negative bacteria. Unfortunately, bacteria have evolved sophisticated resistance mechanisms to combat the lethal effects of β-lactam antibiotics. Pseudomonas aeruginosa, Acinetobacter baumannii and Klebsiella pneumoniae are all able to evade killing by penicillins, cephalosporins and carbapenems. This multi-drug resistant phenotype that challenges healthcare workers worldwide is caused by an array of resistance determinants. These include altered expression of outer membrane proteins and efflux pumps, along with an increasing arsenal of β-lactamases. Future strategies in β-lactam design must take into account the complex nature of resistance in Gram-negative pathogens.