Gram-negative pathogens: Overview of novel and emerging resistant pathogens and drugs

The rising prevalence of multiresistant Gram-negative bacterial infections has become a major clinical problem, as currently such infections comprise the majority of untreatable bacterial infections. The variety of resistance and transfer mechanisms and their rapid spread among Gram-negative bacteria constitutes a global infection control challenge, and an urgent need for development of new antimicrobials. Unfortunately, infection rates with multiresistant nonfermenters, such as Pseudomonas aeruginosa, Acinetobacter baumannii, or extended-spectrum β-lactamase producing Enterobacteriaceae and carbapenem resistant Enterobacteriaceae such as Klebsiella pneumoniae, are growing progressively while the pace of antibiotic drug development has slowed considerably during the last decade. This chapter reviews the main emerging Gram-negative resistant pathogens, their various resistance mechanisms, prevalence, risk factors, and summarizes the novel drugs being developed against them.