The Proteeae are normal fecal flora that often cause infection in patients whose normal flora have been disturbed by antibiotic therapy.

The Proteeae constitute at least 3 genera of gram-negative organisms:

• Proteus: P. mirabilis, P. vulgaris, and P. myxofaciens
• Morganella: M. morganii
• Providencia: P. rettgeri, P. alcalifaciens, and P. stuartii

However, P. mirabilis causes most human infections. These organisms are normal fecal flora and are present in soil and water. They are often present in superficial wounds, draining ears, and sputum, particularly in patients whose normal flora has been eradicated by antibiotic therapy. They may cause bacteremia and deep-seated infections, particularly in the ears and mastoid sinuses, peritoneal cavity, and urinary tract of patients with chronic UTIs or with renal or bladder stones.

P. mirabilis is often sensitive to ampicillinSome Trade Names
OMNIPEN
PRINCIPEN
Click for Drug Monograph
, carbenicillinSome Trade Names
GEOCILLIN

, ticarcillinSome Trade Names
TICAR

, piperacillinSome Trade Names
PIPRACIL
Click for Drug Monograph
, cephalosporins, and aminoglycosides and resistant to tetracyclines. Multidrug-resistant P. mirabilis is an emerging problem. Indole-positive species (P. vulgaris, M. morganii, P. rettgeri) tend to be more resistant but generally are sensitive to fluoroquinolones, carbapenems, piperacillin/tazobactamSome Trade Names
ZOSYN

, 3rd-generation cephalosporins, and cefiximeSome Trade Names
SUPRAX
Click for Drug Monograph
.

Last full review/revision August 2009 by Burke A. Cunha, MD

Content last modified February 2012