Microbiology
Summary
Proteus mirabilis is a gram-negative, facultative anaerobe known for its swarming motility, a key mode of movement. This bacterium is associated with the development of struvite stones, also known as staghorn calculi, which are kidney stones resembling stag horns. These stones form within the renal pelvis, causing kidney pain and impairment, significantly contributing to Proteus' defense and infection strategies. An essential aspect of Proteus is its urease-positive nature. Urease facilitates the conversion of urea into ammonia and carbon dioxide, creating an alkaline environment conducive to the formation of struvite stones. These stones not only cause discomfort and damage but also act as a nidus for recurrent infections associated with Proteus.
Furthermore, Proteus is linked to urinary tract infections (UTIs) and exhibits a distinct fishy odor. Treatment strategies often consider sulfonamides, fluoroquinolones, cephalosporins, carbapenems, and aminoglycosides.
Lesson Outline
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FAQs
P. mirabilis displays a swarming motility, a rapid and coordinated translocation, which helps the bacteria colonize host tissues, evade the immune system, and spread to new infection sites. This feature contributes to recurrent infections, especially in the urinary tract, and is a significant factor in the bacterium's pathogenesis.
P. mirabilis contributes to the formation of staghorn calculi or struvite stones due to the production of the enzyme urease. Urease breaks down urea into ammonia and carbon dioxide, which raises the pH of urine. This alkaline environment promotes the precipitation of organic and inorganic compounds leading to formation of struvite stones. These are a type of kidney stone often seen in urinary tract infections caused by Proteus mirabilis.
A urine sample from a patient with a P. mirabilis infection might have a 'fishy' odor due to the production of amines. Proteus bacteria degrade amino acids, producing amines such as putrescine and cadaverine which have a characteristic fishy odor. This can often be a clue to the presence of a Proteus infection.
P. mirabilis infections are commonly treated with antibiotics that have activity against gram-negative bacteria. While sulfonamides were traditionally used, their effectiveness has decreased in recent years due to antibiotic resistance. Currently, fluoroquinolones, third-generation cephalosporins, and aminoglycosides are often prescribed to combat Proteus infections. However, the choice of antibiotic should be guided by local susceptibility patterns and individual patient factors to ensure effective treatment.
