Proteus Mirabilis

Proteus mirabilis is a Gram-negative, facultatively anaerobic bacterium. It shows swarming motility, and urease activity. P. mirabilis causes 90% of all 'Proteus' infections. It belongs to the Tribe Proteae.

Diagnosis

An alkaline urine sample is a possible sign of P. mirabilis.

P. mirabilis can be diagnosed in the lab due to characteristic swarming motility, and inability to metabolize lactose (on a MacConkey agar plate, for example.) Also P. mirabilis produces a very distinct odour.

Disease

This rod shaped bacterium has the ability to produce high levels of urease. Urease hydrolyzes urea to ammonia (NH₃) and thus makes the urine more alkaline. If left untreated, the increased alkalinity can lead to the formation of crystals of struvite, calcium carbonate, and/or apatite. The bacteria can be found throughout the stones, and these bacteria lurking in the stones can reinitiate infection after antibiotic treatment. Once the stones develop, over time they may grow large enough to cause obstruction and renal failure. Proteus can also cause wound infections, septicemia and pneumonias, mostly in hospitalized patients.

Treatment

P. mirabilis is generally susceptible to most antibiotics apart from tetracycline, however 10%–20% of P. mirabilis strains are also resistant to first generation cephalosporins and ampicillins.

Characteristics

P. mirabilis can utilize urea and citrate. It can produce 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 tract of humans. P. mirabilis is not pathogenic in guinea pigs or chickens. Noteworthy is the ability of this species to inhibit growth of unrelated strains resulting in a macroscopically visible line of reduced bacterial growth where two swarming strains intersect. This line is named Dienes line after its discoverer Louis Dienes.

The micro-organism tests:

• Indole negative and Nitrate reductase positive (no gas bubbles produced)
• Methyl Red positive and Voges-Proskauer negative
• Catalase positive and Cytochrome Oxidase negative
• Phenylalanine Deaminase positive

Proteus Vulgaris

Proteus vulgaris is a rod-shaped, Gram negative bacterium that inhabits the intestinal tracts of humans and animals. It can be found in soil, water and faecal matter. It is grouped with the enterobacteriaceae and is an opportunistic pathogen of humans. It is known to cause urinary tract infections and wound infections.

Notation: Known antibiotics that P. vulgaris is sensitive to:

Ciprofloxacin, Ceftazidime, Netilmicin, Sulbactam or Cefoperazo, Meropenem, Piperacil or Tazobactam, Unasyn.

Antibiotics should be introduced in much higher doses than "normal" when P. vulgaris has infected the sinus or respiratory tissues. I.E.- Ciprofloxacin should be introduced at a level of at least 2000mg per day orally in such a situation, rather than the "standard" 1000mg per day.

According to laboratory conducted fermentation tests, "P. vulgaris" ferments glucose, sucrose, and amygdalin, but does not ferment lactose or mannitol. "P. vulgaris" also tests positive for the Methyl Red (mixed acid fermentation) test and is also an extremely motile organism.

When "P. vulgaris" is tested using the API 20E Identification System [1] test strip for Enterobacteriaceae (made by BIOMERIEUX) [2], it is discovered that it provides a positive result for: sulfur reduction, urease production, tryptophan deaminase production, and indole production, and provides a negative result for the remainder of the tests on the testing strip.

It is referenced in the Analytical Profile Index using the seven-digit code: 0474021

The optimal growing conditions of this organism is in a facultative anaerobic environment with an average temperature of about 23 degrees Celsius .

The term Proteus signifies changeability of form, as personified in the Homeric poems in Proteus, "the old man of the sea," who tends the sealflocks of Poseidon and has the gift of endless transformation. The first use of the term “Proteus” in bacteriological nomenclature was made by Hauser (1885) who described under this term three types of organisms which he isolated from putrefied meat. One of the three species Hauser identified was Proteus vulgaris so this organism has a long history in Microbiology.

Over the past two decades the genus Proteus, and in particular P. vulgaris, has undergone a number of major taxonomic revisions. In 1982, P. vulgaris was separated into three biogroups on the basis of indole production. Biogroup one was indole negative and represented a new species: P. penneri; while biogroup two and three remained together as P. vulgaris.