A genus of Gram-negative, aerobic non-fermenting bacilli that are commonly found in the environment. P. aeruginosa is a clinically relevant species in hospitalized patients.

P. aeruginosa is a common cause of hospital-acquired infections (HAIs). It can cause many types of infection, including bloodstream infections, urinary tract infections and pneumonia. It is a common bacterial infection of the lungs of people with cystic fibrosis.

P. aeruginosa is naturally resistant to many antibiotics and is also adept at acquiring resistance through horizontal gene transfer and mutations in genes on its chromosome. Its resistance mechanisms include the ability to increased production of multiple drug efflux pumps and decrease production of porin proteins. Together these reduce the intracellular concentrations of many antibiotics. P. aeruginosa is categorized by WHO as a ‘priority 1 (critical)’ pathogen for R&D of new antibiotics.