00:00 / 00:00
0 / 6 complete
0 / 2 complete
cephalosporins p. 186
kidney stones p. 628
penicillins for p. 185
urinary tract infections p. 625
UTIs p. 179
Proteus mirabilis is a Gram-negative bacillus which belongs to a family of bacteria called the Enterobacteriaceae.
It is widely distributed in soil and water and can also be found in the normal human intestinal flora.
Now, Proteus mirabilis has a thin peptidoglycan layer, so it doesn’t retain the crystal violet dye during Gram staining. Instead, like any other Gram-negative bacteria, it stains pink with safranin dye.
And since it’s a Gram-negative bacillus, it looks like a little pink rod under the microscope.
Alright, now Proteus mirabilis is non-spore forming and highly motile.
It’s also facultative anaerobic which means it can survive in both aerobic and anaerobic environments, non-lactose fermenter, oxidase negative which means it doesn’t produce this enzyme, and urease positive which means it can produce an enzyme called urease.
Now, it grows well on blood agar and MacConkey agar.
On blood agar, it has a swarming growth, so it moves and forms a thin filmy layer of concentric circles, which look like the ripples after you throw a rock into a lake.
On MacConkey agar, however, it doesn’t swarm so it forms smooth, pale or colourless colonies.
Finally, the triple sugar iron test, or TSI for short can be done to assess hydrogen sulfide production.
This medium contains three sugars - lactose, glucose and sucrose, as well as iron and a pH sensitive dye.
Now, when Proteus mirabilis comes in contact with solid surfaces, especially urinary catheters, it has the ability to differentiate from short swimmer cells into elongated swarm cells that express hundreds to thousands of flagella, and interact with each other to form multicellular rafts.
Proteus mirabilis is a gram-negative, facultatively anaerobic, rod-shaped bacterium. It is commonly found in the human intestinal tract and urinary tract and is known for its ability to produce urease, an enzyme that breaks down urea, which can lead to the formation of struvite crystals in the urinary tract and cause kidney stones. This bacteria can be identified in a urine culture, and the treatment of its infections involves antibiotics like trimethoprim-sulfamethoxazole, fluoroquinolones, and cephalosporins.
Copyright © 2023 Elsevier, its licensors, and contributors. All rights are reserved, including those for text and data mining, AI training, and similar technologies.
Cookies are used by this site.
USMLE® is a joint program of the Federation of State Medical Boards (FSMB) and the National Board of Medical Examiners (NBME). COMLEX-USA® is a registered trademark of The National Board of Osteopathic Medical Examiners, Inc. NCLEX-RN® is a registered trademark of the National Council of State Boards of Nursing, Inc. Test names and other trademarks are the property of the respective trademark holders. None of the trademark holders are endorsed by nor affiliated with Osmosis or this website.