Proteus

Gustav Hauser 1885

Proteus (named after the Greek god of the sea, described as highly changeable in appearance) refers to a genus of bacteria in the order Enterobacterales and the family Morganellaceae. The genus Proteus consists of 5 species of which 3 are of human medical importance:

• Proteus mirabilis
• Proteus vulgaris
• Proteus penneri.

In addition, there are three unnamed genomopecies 4, 5 and 6. Currently, 80 O-antigenic serogroups can be distinguished (Armbruster CE et al.).

Proteus are gram-negative, sporeless rod-shaped bacteria. They are peritrichous flagellated and vividly motile. Various carbohydrates (glucose, maltose and sucrose) are utilized as carbon and energy sources. In doing so, they carry out fermentations under anoxic conditions, for example mixed acid fermentation. Proteus species cannot utilize the disaccharide lactose. The enzyme β-galactosidase is missing. Furthermore, they reduce nitrate to nitrite.

Some members of the genus Proteus are facultatively pathogenic (opportunistic) pathogens. They are also found in the colon of healthy individuals without causing symptoms of disease. The extent to which Proteus species play a causative role in Crohn's disease is currently unclear (Hamilton AL et al. 2018; Wright EK et al. 2017). Proteus (primarily Proteus mirabilis and Proteus vulgaris) cause urinary tract infection, wound infection, and sepsis. In urinary tract infections, urease present in the bacteria apparently acts as a virulence factor. Its activity leads to the cleavage of urea, resulting in the formation of ammonia. This leads to an increase in pH and to the crystallisation of salts and can ultimately promote the formation of kidney stones. In contrast to Proteus mirabilis, the ability of Proteus vulgaris to form indole is typical.

The diagnosis is verified, as with all Enterobacteraceae, by the failure to check metabolic performance. This is done by means of "colorful series". Furthermore, an assignment can be made by means of MALDI-TOF mass spectrometry. Typical is the indole formation of P. vulgaris.

1. Armbruster CE et al. (2017) Pathogenesis of Proteus mirabilis infection. EcoSal Plus 8:10.1128/ecosalplus.ESP-0009-2017.
2. Gomaa S et al. (2019) Elimination of multidrug-resistant Proteus mirabilis biofilms using bacteriophages. Arch Virol 164:2265-2275.
3. Hamilton AL et al (2018) Proteus spp. as putative gastrointestinal pathogens. Clin Microbiol Rev. 31:e00085-17.
4. Mobley HLT (2019) Proteus mirabilis Overview. Methods Mol Biol 2021:1-4.
5. Wright EK et al (2017) Microbial factors associated with postoperative Crohn's disease recurrence. J Crohns Colitis 11:191-203
6. Yazdi M et aal. (2018) Isolation and Characterization of a Lytic Bacteriophage (vB_PmiS-TH) and Its Application in Combination with Ampicillin against Planktonic and Biofilm Forms of Proteus mirabilis Isolated from Urinary Tract Infection. J Mol Microbiol Biotechnol 28:37-46.