Proteus

Proteus

The genus Proteus along with two other genera Morganella and Providencia belongs to the tribe Proteeae. The name “Proteus”(after the Greek god Proteus who could assume any shape) refers to their property of pleomorphism. All the members of the tribe Proteeae with few exceptions are Gram negative, noncapsulated, pleomorphic, and motile bacilli. Most of these bacteria, except for some strains of Providencia, produce the enzyme urease which rapidly hydrolyses urea to form ammo-nia and carbon dioxide. They are MR positive and VP nega-tive, degrade tyrosine, and grow in the presence of KCN. They do not decarboxylate amino acids, such as arginine or lysine or dehydrogenase ornithine. They do not ferment lactose or dulcitol, and do not utilize malonate. The formation of the enzyme phenyl alanine deaminase, which converts phenyl ala-nine to phenyl pyruvic acid (PPA reaction), is the characteristic feature of the tribe Proteeae by which they are differentiated from other members of the family Enterobacteriaceae. The dif-ferentiating features of different genera in the tribe Proteeae are summarized in Table 31-11.

The genus Proteus has four species: Proteus mirabilis, Proteusvulgaris, Proteus penneri, and Proteus myxofaciens. P. mirabilis is themost important species, which causes 90% of Proteus infections and is associated with community-acquired urinary tract and wound infection. P. vulgaris and P. penneri are usually associ-ated with hospital-acquired infections. They are isolated from patients with chronic debilitating diseases and from those who are immunocompromised.