Proteus infection

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief:

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Yazan Daaboul, M.D.

Proteus infections were first described by Gustav Hauster, a German pathologist, in 1885. Hauster coined the term Proteus based on the organism’s ability to change shape from Homer’s Greek tale, the Odyssey.

• Proteus infections were first described by Gustav Hauster, a German pathologist, in 1885.
• Hauster coined the term Proteus based on the organism’s ability to change shape from Homer’s Greek tale, the Odyssey. Proteus refers to the “sea god” or “Poseidon’s herdsman of the seals”.^[1]
• Hauser also coined the terms P. vulgaris (i.e. the usual) and P. mirabilis (i.e. the marvelous or the unusual).

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Proteus is part of the normal human gastrointestinal flora and is usually associated with development of urinary tract infections (most common), pnuemonia, and local wound infections by self-contamination. Following self-contamination, Proteus accesses the urinary tract through the urethra and overproduces flagella (transforms from swimmer to swarmer) to ascend in a retrograde manner to the upper urinary tract. In the bladder, Proteus uses fimbriae and adhesins to bind to mucosal surfaces. To avoid host defenses, Proteus produces virulence factors, such as IgA-degrading protease, hemolysin, and urease. As urease is produced, urea is hydrolyzed to ammonia and carbon dioxide, resulting in the increase in the local pH of the urinary tract and precipitation of magnesium and calcium ions. As ions precipitate, strutive (magnesium ammonium phosphate) stones form and epxand, giving Proteus the capacity to sequester within the stone cavities and to protect itself against the host defenses and antimicrobial agents.

• Proteus is part of the normal human gastrointestinal flora and is usually associated with development of urinary tract infections (most common), pnuemonia, and local wound infections by self-contamination.
• Following self-contamination, Proteus accesses the urinary tract through the urethra and uses flagella to ascend in a retrograde manner to the upper urinary tract.^[1]
• During the motility process, the production of flagella markedly increases, and the organism changes from a single-cell, rod-shaped form (swimmer) to a multi-cell, elongated-form (swarmer).^[2][1]
• In the bladder, Proteus uses fimbriae and adhesins to bind to mucosal surfaces:^[1]

• Mannose-resistant fimbriae (MRF)
• P. mirabilis fimbriae (PMF)
• Ambient temperature fimbiae
• Non-agglutinating fimbiae
• P-like pilus

• There are four mechanisms by which Proteus can use to evade the host defenses:^[1][2]

• Production of an IgA-degrading protease which functions to cleave the secretory IgA.
• Expression of flagellin to synthesize flagella that provides the characteristic swarming motility of Proteus.
• Expression of the MR/P fimbriae
• Production of urease (increases pH) to provide an adequate medium for bacterial growth. Urease production is also associated with stone formation in the kidneys and the bladder.^[3]

Production of hemolysin, a cytotoxin involved in injury of host epithelial cells are known to cause damage to host epithelial cells. As mentioned above, urease can damage host epithelial cells through the formation of stones. Hemolysin damages cells

• Proteus produces urease, which catalyzes the hydrolysis of urea tot ammonia and carbon dioxide.^[4]
• The ammonia results in an increase in the local pH of the urinary tract, resulting in the precipitation of magnesium and calcium ions and subsequent formation of struvite (composed of magnesium ammonioum phosphate) and carbonate hydroxyapatite stones.^[4][5][3]
• Proteus is able to sequester in the stone cavities and replicate while avoiding host defenses and therapeutic agents.^[5]
• As the infection persists or as the human host is re-infected, the existing stone expands and occasionally blocks the urinary tract completely. Large stones are referred to as Staghorn calculi, given their resemblance to the horns of a stag (adult male deer).

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Proteus species are classified into four main serogroups: P. vulgaris, P. mirabilis, P. penneri, P. rettgeri, and P. morganii.

Proteus species are classified into four main serogroups:

• P. mirabilis
• P. vulgaris

• P. penneri
• P. rettgeri
• P. morganii

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Proteus is a urease-producing, motile, nitrite-reducing, hydrogen sulfide-producing, catalase-positive, facultatively anaerobic, Gram-negative bacillus. It can be found in soil, water, and fecal matter. It inhabits the intestinal tracts of humans and animals, and is considered an opportunistic pathogen of humans. Transmission to the human host (usually urinary tract) typically occurs via self-contamination.

Kingdom: Bacteria; Phylum: Proteobacteria; Class: Gamma proteobacteria; Order: Enterobacteriales; Family: Enterobacteria; Genus: Proteus; Species: Proteus mirabilis

• Proteus contains more than 3,658 coding sequences with 7 rRNA loci.^[1]
• Total genome length is 4.063 Mb (28.8% GC content).^[1]
• Proteus contains a single plasmid that contains 26,298 nucleotides.^[1]

• Proteus is a urease-producing, motile, nitrite-reducing, hydrogen sulfide-producing, catalase-positive, facultatively anaerobic, Gram-negative bacillus.
• It grows optimally at 40 °C (104 °F).
• It produces hydrogen sulfide gas, and forms clear films on growth media. It is motile, possessing peritrichous flagella, and is known for its swarming ability. It is commonly found in the intestinal tracts of humans. P. mirabilis is not pathogenic in guinea pigs or chickens.
• Characteristically, Proteus can inhibit the growth of other strains in culture media, resulting in a macroscopically visible line (Dienes line) of reduced bacterial growth where two swarming strains intersect.
• The following table summarizes the microbiological characteristics of Proteus:

• Proteus can be found in soil, water, and fecal matter.
• It inhabits the intestinal tracts of humans and animals, and is considered an opportunistic pathogen of humans.

• Proteus is usually transmitted to the human host by self-contamination (e.g. fecal material from gastrointestinal tract to genitourinary tract).

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Hari Krishnan Nair, M.D.

Proteus infection must be differentiated from other types of infectious diseases that cause acute urinary tract infection, pneumonia and local wound infections such as Escherichia coli, Klebsiella and Pseudomonas.

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Hari Krishnan Nair, M.D.

Proteus infections occur worldwide, and are generally considered pathogenic for young individuals and opportunistic pathogens for the elderly. The elderly, particularly those who are on long-term catheterization or under frequent antibiotic therapy, prepubescent males and females, and individuals with structural abnormalities of the urinary tract are more susceptible to infection.