Patients with multiple antibiotic treatments, urinary tract obstruction, or infection developing after catheterization or instrumentation frequently become infected with Proteus spp. or other bacteria, such as Enterobacter spp., Klebsiella spp., Serratia spp., andAcinetobacter spp. Proteus species cause (a) urinary tract infections, (b) hospital-acquired infections, and (c) other miscel-laneous infections.
UTIs are the most common clinical manifestation of Proteus infections. Proteus is responsible for nearly 1–2% of UTIs in healthy women and 5% of hospital-acquired UTIs. It is responsible for 20–45% of UTIs associated with catheteriza-tion. Patients with UTI may present with urethritis, cystitis, prostatitis, or pyelonephritis. Chronic UTI is associated with chronic, recurring stones. Urine sediments show multiple mag-nesium ammonium phosphate crystals.
Hospital-acquired infections are usually transmitted from attending doctors or other healthcare workers and are caused by interruption of the closed sterile system by hospital staff.
Proteus species is an important agent of wound infections. Thespecies also causes infection of the umbilical stump in neo-nates, which often leads to sepsis neonatorum, bacteremia, and meningitis. Proteus spp. also causes nonclostridial anaerobic myonecrosis, a condition which involves subcutaneous tissue, fascia, and muscle. This condition usually occurs in association with other aerobic Gram-negative bacilli (E. coli, Klebsiella spp., or Enterobacter spp.) and anaerobes. Proteus organisms like that of Pseudomonas can cause Gram-negative endotoxin-induced sepsis, resulting in systemic inflammatory response syndrome, which has a mortality rate of 20–50%.