ABSTRACT
Classi©cation. Proteus rods were described for the Šrst time by Hauser in 1885.1 Proteus belongs to the Enterobacteriaceae family, and formerly this genus was placed in the tribe Proteeae with Morganella and Providencia rods.2 Apart from Proteus mirabilis and Proteus vulgaris, the two Šrst species described, the genus Proteus contains also biochemically distinct bacteria, named P. myxofaciens. This species is the only Proteus species without any signiŠcance in the pathogenicity of human beings.3 P. myxofaciens produces slime rods, isolated from larvae of the gypsy moth.4 The biochemical as well as DNA-DNA hybridization analyses showed the homogeneity of P. mirabilis and heterogeneity of P. vulgaris species, which was subdivided into three biogroups based on fermentation of salicin, esculin hydrolysis, and indole production. Results of further studies made it possible to name biogroup 1 (genomospecies 1) Proteus penneri. These bacteria are indole-, esculin-, and salicin-negative.5 The name P. vulgaris was reassigned to biogroup 2 (genomospecies 2), as it turned out to be homogenous and represented a single species.6 The biogroup 3, consisting of four genomospecies, were studied using molecular and biochemical methods. Results of this study allowed O’Hara et al.7 to propose the separation of genomospecies 3 (DNase-, lipase-, and tartrate-negative) from another genomospecies, which was named Proteus hauseri. The Proteus genomospecies 4, 5, and 6 remained unnamed until now. Currently, the genus Proteus consists of Šve named species: P. mirabilis (type
strain ATCC 29906), P. vulgaris (ATCC 29905), P. penneri (ATCC 33519), P. hauseri (ATCC 700826 and ATCC 13315), and P. myxofaciens (ATCC 19692), as well as Proteus genomospecies 4 (ATCC 51469), 5 (ATCC 51470), and 6 (ATCC 51471).3,6
Environmental Distribution and Pathogenicity. Proteus rods are a group of gram-negative bacteria that are widespread in the natural environment. Because of their proteolytic activity and their ability to hydrolyze urea to ammonia and carbon dioxide, as well as the oxidative deamination of amino acids, these bacteria play an important role in decomposing organic matter of animal origin. Therefore, they can most often be found in polluted water, soil, and manure. Proteus bacteria are also a part of natural ³ora of the human and animal gastrointestinal tracts.2 They are frequently isolated from human and animal feces, as well as from associated sources such as sewage and decomposing meat. P. mirabilis is a common inhabitant of dogs, cows, and birds. P. vulgaris is often recovered from cows and birds; however, in contrast to P. mirabilis, this species is more frequently isolated from pigs than from dogs.8 Human feces were found as a source of nosocomial infections caused by P. mirabilis.9 P. vulgaris and P. penneri were isolated from stools with a wide range of frequencies: 0.45%–6% and 0.4%–1.2%, respectively.3 There is no evidence supporting the classiŠcation of Proteus rods as enteropathogens.
