Pseudomonas aeruginosa is Gram-negative, aerobic, rod-shaped bacteria with unipolar motility. An opportunistic human pathogen, P. aeruginosa is also an opportunistic pathogen of plants. P. aeruginosa bacteria are clinically important because they are resistant to most antibiotics and they are capable of surviving in conditions that few other organisms can tolerate. Pseudomonas is often encountered in hospital and clinical work because it is a major cause of hospital acquired (nosocomal) infections. Its main targets are immunocompromised individuals, burn victims, and individuals on respirators or with indwelling catheters. Additionally, these pathogens colonize the lungs of cystic fibrosis patients. P. aeruginosa is often identified by its pearlescent appearance and grape-like odor in vitro. Definitive clinical identification of P. aeruginosa includes identifying the production of both pyocyanin and fluorescein as well as its ability to grow at 42 centigrade. P. aeruginosa is capable of growth in diesel and jet fuel, where it is known as hydrocarbon utilizing microorganisms (or "HUM bugs"), causing microbial corrosion. It creates dark gellish mats sometimes improperly called "algae".