It is an opportunistic pathogen: while it can cause minor infections such as folliculitis in healthy people, severe infections usually only occur in people who are immunocompromised or whose defences have been breached, such as oncology patients, neonates, severe burn patients, those with invasive medical devices, and people with cystic fibrosis. P.aeruginosa infections in vulnerable people can include: bacteraemia, pneumonia (including ventilator-associated pneumonia), infections of wounds, gastrointestinal tract and urinary tract infections.