Most Proteus infections arise from the urinary tract. Proteus species account for 1-2% of uncomplicated UTIs, 5% of hospital-acquired UTIs, and 10-15% of complicated UTIs (especially those associated with urinary catheters).

• Proteus produces high levels of urease that result in alkalinization of urine and ultimately in formation of struvite and carbonate-apatite calculi.
• Infections at other sites are uncommon but include pneumonia, abdominal infections, soft tissue infections, and bacteremia.