Proteus mirabilis

A Gram-negative, facultatively anaerobic, rod-shaped bacterium, in a family Enterobacteriaceae.
It is widely distributed in soil and water. It is motile, possessing peritrichous flagella (all over its surface), and a large number of them can migrate across the surface of solid media or devices in a coordinated motion (swarming).
It produces high levels of urease, which hydrolyzes urea to ammonia (NH3), so 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, resulting in formation of kidney stones.
The bacterium can be found throughout the stones. It can reinitiate infection after antibiotic treatment.
It can also cause obstruction and kidney failure once the stones develop large enough.
(Diseases)
Particularly found in the elderly and patients with type 2 diabetes and in hospital.
• urinary tract infections (e.g. cystitis, pyelonephritis), especially complicated or catheter-associated urinary tract infections
• wound infections
• sepsis or life-threatening urosepsis
• urolithiasis
• pneumonia
(Diagnosis)
• alkaline in urine sample
• asymptomatic bacteriuria
• characteristic swarming motility
• inability to metabolize lactose (e.g. on a MacConkey agar plate)
• very distinct fishy odor
(Drug resistance)
• tetracyclines
• polymyxins
• nitrofurantoin
For some strains:
• first-generation cephalosporins: E.g. cephalexin, cefadroxil, cephradine.
• ampicillin
(Treatment)
• Correction of the underlying anatomical abnormality.
• Removal of a urinary catheter.
• antibiotics: E.g. aminoglycosides (e.g. tobramycin, gentamicin, paromomycin), carbapenems (except imipenem), and 3rd generation cephalosporins.