9.2

• MAC - positive

  • Pseudomonas
  • Burkholderia
  • Achromobacter
  • Chryseobacterium
  • Sphingobacterium
  • Alcaligenes
• Gram Negative Bacilli

  • Bordetella (NP)
  • Comamonas
  • Vibrio
  • Aeromonas
  • Plesiomonas
  • Chromobacterium

  
• Pseudomonas

  • Non-fermentative gram negative bacilli
  • Strictly aerobic
  • Catalase-positive
  • Oxidase-positive
• Pseudomonads oxidase positive except Burkholderia cepacia and Stenotrophomonas
• Pseudomonas aeruginosa produces slime polysaccharide, endotoxin, and proteases that inactivate components of complement
• Pseudomonas aeruginosa is only rarely found as part of the normal flora
• Pseudomonas aeruginosa is ubiquitous in the hospital
• Pseudomonas aeruginosa exists almost anywhere there is moisture, including medical equipment and disinfectant solutions and soaps
• Pseudomonas aeruginosa


  Agent of “blue pus”
• Pyocyanin


  Blue pigment produced by P. aeruginosa
• Other pigments produced by some strains of P. aeruginosa

  • Pyoverdin
  • Pyorubin
  • Pyomelanin
• P. aeruginosa colonies on Tryptic Soy Agar exhibit a blue-green color
• Diseases produced by P. aeruginosa

  • UTI
  • Pneumonia
  • Otitis media/externa
  • Eye infection in contact lens wearer
  • Skin lesion (Ecthyma gangrenosum)
• Ecthyma gangrenosum is characterized by black necrotizing skin lesions
• Hearing might be temporarily affected if pus and debris or swelling of the canal blocks the passage of sound into the ear
• Biochemical Reactions of P. aeruginosa

  • TSI: K/K with a metallic sheen on the slant surface
  • Oxidase and catalase (+)
  • Lysine and ornithine decarboxylase (-)
  • Dihydrolyze arginine
• Burkholderia

  • Aerobic, non–spore-forming, gram-negative rods
  • Most are motile due to polar flagella
  • Catalase positive
  • Most are oxidase positive
  • Produce lactose-negative colonies on MacConkey’s agar
• Burkholderia mallei causes glanders, a disease of horses transmissible to man
• Burkholderia pseudomallei causes melioidosis
• Burkholderia cepacia is a nosocomial pathogen associated with contaminated equipment, medications, and disinfectants
• Infections associated with Achromobacter spp.

  • Bacteremia
  • Meningitis
  • Pneumonia
  • Peritonitis
• Chryseobacterium spp. are known for their ability to survive in hospital environments, especially in moist areas
• Key Biochemical and Physiologic Characteristics

  • Oxidizes Mannitol
  • Indole
  • Urea
• Alcaligenes

  • Oxidase & catalase (+)
  • Utilize acetate as sole source of carbon
  • Opportunistic pathogen
• Alcaligenes species

  • A. feacalis
  • A. xylosoxidans subspecie xylosoxidans
  • A. xylosoxidans subspecie denitrificans
  • A. piechaudii
• Comamonas spp. are environmental species that may be problematic opportunistic nosocomial pathogens
• Family groupings changed due to phylogenetic studies

  • Vibrio – family Vibrionaceae
  • Aeromonas – family Aeromonadaceae
  • Plesiomonas – family Enterobacteriaceae
• Vibrio, Aeromonas, Plesiomonas

  • Oxidase-positive
  • Glucose fermenting
  • Grow on MacConkey agar
  • Primary habitat is water
  • Not part of the normal flora
• Significance of isolates should be interpreted with caution
• Isolates have been found in

  • Blood
  • Respiratory specimens
  • Urine
• Alcaligenes faecalis

  Non-pertussis
• Environmental species that may be problematic opportunistic nosocomial pathogens

  • Bordetella
  • Comamonas
• Characteristics of certain bacteria

  • Aerobic
  • Non–spore forming
  • Straight or slightly curved
  • Gram-negative rods with one or more polar flagella
• These bacteria have been identified in cases of endocarditis, meningitis, and catheter-associated bacteremia
• They have also been recovered from sputum in patients with cystic fibrosis
• Family groupings changed due to phylogenetic studies

  • Vibrio – family Vibrionaceae
  • Aeromonas – family Aeromonadaceae
  • Plesiomonas – family Enterobacteriaceae
• Family Vibrionaceae

  • Oxidase-positive
  • Glucose fermenting
  • Grow on MacConkey agar
  • Primary habitat is water
  • Not part of the normal flora
• Vibrio are motile because of a single polar flagella
• Characteristics of Vibrio

  • Oxidase (+)
  • Facultative anaerobe
  • Halophilic – except V. cholerae & V. mimicus
  • Requires alkaline environment
  • Ferments carbohydrates
  • Reduces nitrates to nitrites
• Vibrio cholerae


  Also known as V. comma or Spirillum cholera asiaticae