**3. Pseudomonas aeruginosa a critical opportunistic bacterium**

*Pseudomonas aeruginosa*, is one such opportunistic Gram-negative rod-shaped bacterial pathogen known for its ubiquity. World health organization (WHO) have placed *P. aeruginosa* in top priority (critical) organism list considering its intrinsic antibiotic resistance profile and remarkable ability to acquire tolerance to antibacterial agents [19]. In addition, *P. aeruginosa* forms robust biofilm and triggers severe infections especially in immunocompromised and hospital admitted patients. *P. aeruginosa* commonly found in human gastrointestinal tract, skin, soil, water, meat, plants, and vegetables and one of the leading causes for blood stream infection, UTI, microbial keratitis, wound and burn infection, HIV/AIDS patients, in ICU patients (ventilator associated pneumoniae) and a leading death cause in cystic fibrosis patients. *P. aeruginosa* associated hospital-acquired infections ranges between 10 and 15% globally [20]. Global epidemiology survey on *P. aeruginosa*, recorded numerous antibiotic resistance strains isolated from infected patients. These isolates are resistance to many antibiotics (carbapenem, gentamicin, ciprofloxacin, tobramycin, meropenem, and others) which are commonly used to treat infected patients [21–24]. This bacterium secretes numerous biomolecules such as DNA, proteins, polysaccharides, pyocyanin, rhamnolipids, siderophores which supports them in colonization at infection site and spread virulence in host and shield them from antibacterial agents [25]. In this book, we elaborated on general bacterial biofilm and in specifically focused on mechanism of *P. aeruginosa* biofilm formation, pathogenicity, antibiotic resistance, and treatment. The collections of chapters in this book will enlighten different end users including infectious diseases scientist, medical professional, medical and microbiology students and public.
