Proteus

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Proteus
Proteus vulgaris growth in MacConkey agar culture plate Proteus vulgaris growth in MacConkey agar culture plate
Scientific classification
Domain: Bacteria Phylum: Proteobacteria Class: Gamma Proteobacteria Order: Enterobacteriales Family: Enterobacteriaceae Genus: Proteus Hauser 1885
Species
P. mirabilis P. morganii Proteus penneri (P. penneri) P. rettgeri P. vulgaris etc.

This page is about microbiologic aspects of the organism(s).  For clinical aspects of the disease, see Proteus infection.

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

Overview

P. mirabilis 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.

Microbiological Characteristics

• P. mirabilis 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:

Test	Result
Indole	Negative
Nitrate reductase	Positive (no formation of gas bubbles)
Methyl red	Positive
Voges-Proskauer	Negative (VP may be positive)
Catalase	Positive
Cytochrome oxidase	Negative
Phenylalanine deaminase	Positive
Tryptophan	Negative
Urea (Harnstoff test)	Positive
Casein	Negative
Starch	Negative
Hydrogen sulfide	Positive
Citrate agar	Negative
Ornithine decarboxylase	Positive
Lysine decarboxylase	Negative
Glucose fermentation	Positive
Amygdalin fermentation	Positive
Mannitol fermentation	Negative
Lactose fermentation	Negative

Natural Reservoir

• 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.

Transmission

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