Being Gram-negative bacteria, most Pseudomonas spp. are naturally resistant to penicillin and the majority of related beta-lactam antibiotics, but a number are sensitive to piperacillin, imipenem, ticarcillin, or ciprofloxacin. Aminoglycosides such as tobramycin, gentamicin, and amikacin are other choices for therapy.This ability to thrive in harsh conditions is a result of their hardy cell walls that contain porins. Pseudomonas aeruginosa is increasingly recognized as an emerging opportunistic pathogen of clinical relevance. One of its most worrying characteristics is its low antibiotic susceptibility.This low susceptibility is attributable to a concerted action of multidrug efflux pumps with chromosomally encoded antibiotic resistance genes.Pseudomonas aeruginosa is a major cause of nosocomial infections. P. aeruginosa continue to be the commonest cause of hospital infections. The diversity of clinics and the regional variations in antibiotic protocols result in the different resistance profiles.Keeping these all parameters this book will help in understanding extended spectrum beta-lactamase by Pseudomonas spp. isolated from pus, sputum, CSF, blood, urine, and other body fluid.