Serratia is a genus of Gram-negative, facultatively anaerobic, rod-shaped bacteria of the Enterobacteriaceae family. The most common species in the genus, S. marcescens, is normally the only pathogen and usually causes nosocomial infections. However, rare strains of S. plymuthica, S. liquefaciens, S. rubidaea, and S. odoriferae have caused diseases through infection. Members of this genus produce characteristic red pigment, prodigiosin, and can be distinguished from other members of the Enterobacteriaceae family by their unique production of three enzymes: DNase, lipase, and gelatinase.