Illustration of Pseudomonas aeruginosa bacteria showing internal structure. These Gram-negative rod-shaped bacteria are found in soil, water and as normal flora in the human intestine. They can cause serious wound, lung, skin and urinary tract infections, particularly in hospital patients. They produce extracellular polysaccharide (EPS), a sticky slime-like substance that enables them to grow in large masses (biofilms) and resist antibacterial agents such as antibiotics.