Properties

Pathogenesis

Clinical findings

Laboratory diagnosis

Treatment & Prevention

Gram-negative rods.

Distinguished from other species by ability to produce enzyme phenylalanine deminase.

Produce enzyme urease.

Motile – ‘swarming’ effect on blood sugar, characterized by expanding rings of organism over the surface of the agar.

Organisms are present in the human colon as well as in soil & water.

Their tendency to cause urinary tract infections is due to their presence in the colon & to colonization of the urethra, especially in women.

Production of  enzyme urease which hydrolzyes urea in urine to form ammonia, raising the pH and encourages the formation of calculi.

Diseases:

- urinary tract infections.

- pneumonia

- wound infections

- septicemia

Signs & symptoms of urinary tract infections caused by these organisms cannot be distinguished from those caused by E.coli or other Enterobacteriaceae.

P.mirabilis is the species of Proteus  that causes most community & hospital-acquired infections.

Produce non-lactose-fermenting (colorless) colonies on MacConkey’s or EMB agar.

P.mirabilis is indole-negative while the other species are indole-positive – P.vulgaris, morganii & Providencia.

Most strains are sensitive to aminoglycosides & trimethoprim-sulfamethoxazole.

P.mirabilis most sensitive to ampicillin.

Treatment of choice for indole-positive species is a cephalosporin, e.g. cefotaxime.