PROTEUS–PROVIDENCIA– MORGANELLA GROUP

Question 1

Diseases

Answer 1

UTIs both community- & hospital-acquired

Question 2

Important Properties

Answer 2

• produce phenylalanine deaminase & urease (cleaves urea to form NH3 & CO2).
• motile, produce a swarming effect on blood agar with expanding rings (waves) of organisms.
• cell wall O antigens of Proteus strains (OX-2, OX-19, & OX-K), cross-react with antigens of rickettsiae species.
• Proteus antigens used to detect antibodies presence against certain rickettsiae in patients’ serum-> Weil-Felix reaction.

Question 3

Pathogenesis & Epidemiology

Answer 3

• present in human colon, soil & water.
• Cause UTIs->presence in colon &
  colonization of urethra in women through vigorous motility.
• Urease hydrolyzes urea in urine forming ammonia->raises pH, producing alkaline urine-> struvite stones (calculi) of magnesium ammonium phosphate.
• present as staghorn calculi in renal pelvis->obstruct urine flow, damage urinary epithelium, & serve as nidus for recurrent infection by trapping bacteria within stone.
• Alkaline urine-> favors growth of
  organisms & more extensive renal damage; treatment->low pH urine.

Question 4

Clinical Findings

Answer 4

• symptoms of UTI cannot be distinguished from Enterobacteriaceae.

-pneumonia, wound infections, & septicemia.
- Proteus mirabilis-> most community- & hospitalacquired
infections; P. rettgeri -> nosocomial infections.

Question 5

Lab Diagnosis

Answer 5

• swarming overgrowth on blood agar-> frustrating to recover pure cultures of other organisms.
• Growth on blood agar containing phenylethyl alcohol inhibits
  swarming, allowing isolated colonies to be obtained.
• produce non–lactose-fermenting (colorless) colonies on MacConkey’s or EMB agar.
• P.vulgaris & P. mirabilis produce H2S-> blackens butt of TSI agar; M.
  morganii nor P. rettgeri does.
• P.mirabilis-> indolenegative; other 3-> indolepositive
• all 4-> urease-positive.

Question 6

Treatment

Answer 6

• Most strains sensitive to aminoglycosides &
  trimethoprim-sulfamethoxazole
• P.mirabilis-> most sensitive
  to ampicillin.
• indole-positive species (P. vulgaris,
  M. morganii, & P. rettgeri) more resistant to antibiotics than P. mirabilis (indole-negative).
• indole-positive->cephalosporin
  (cefotaxime).
• P.rettgeri-> resistant to multiple antibiotics.

Question 7

Prevention

Answer 7

• hospital-acquired UTIs prevented by prompt removal of urinary catheters.