BACTE

• Pseudomonas spp.


  The genus Pseudomonas accounts for the largest percentage of all nonfermenters isolated from clinical specimens.
• Pseudomonas spp.


  Usually an oxidizer of carbohydrates, but some species are asaccharolytic

  - the optimal temperature range for growth of most species is 30°C to 37°C; that is, they are mesophilic
• Pseudomonas aeruginosa


  most commonly isolated species of the genus in clinical specimens.

  - It is found in moist environments, including tap water, pools, hot tubs, catheters, and humidifiers in hospitals, and in plants and soil.
• Pseudomonas aeruginosa


  bacterimia, often presenting with ecthyma gangrenosum; wound infections; pulmonary disease: VAP, especially among individuals with CF; healthcare-associated urinary tract infections (UTIs); endocarditis; bone infections; eye infections, including keratitis, ulcers, and endophthalmitis; infections following burns or trauma; and in rare cases, central nervous system infections, including meningitis
• P. aeruginosa: otitis externa

  particularly in swimmers or divers; necrotizing rash

  
  

  referred to as Jacuzzi or hot tub syndrome
• Pseudomonas aeruginosa


  can survive harsh environmental conditions and displays intrinsic resistance to a wide variety of antimicrobial agents
• pyoverdin


  a yellow-green or yellow- brown pigment.
• pyocyanin


  blue water soluble pigment
• Pyocyanin combining with pyoverdine


  produces the green color characteristic of P. aeruginosa colonies
• pyorubin


  red
• Pyomelanin


  brown or black
• pseudomonas fluorescent group


  fruity, grapelike odor caused by the presence of 2- aminoacetophenone
• Cetrimide agar


  a selective and differential medium for the identification of P. aeruginosa.
• piperacillin and ticarcillin

  
  

  third- and fourth-generation cephalosporins (ceftazidime and cefepime, respectively), carbapenems (except ertapenem), and the fluoroquinolones.


  P. aeruginosa is usually susceptible to the aminoglycosides, semi-synthetic penicillins
• Treatment of severe P. aeruginosa


  requires combination therapy, often with ceftazidime or cefepime, piperacillin, or a carbapenem (imipenem or meropenem) with an aminoglycoside (tobramycin or amikacin).
• Pseudomonas fluorescens and Pseudomonas putida

  are of very low virulence, rarely causing clinical disease

  
  

  Both species can grow at 4° C and have been linked to transfusion-associated septicemia.

  
  

  Produce pyoverdin, but neither produces pyocyanin or grows at 42° C

  
  

  cannot reduce nitrate to nitrogen gas, but they can produce acid from xylose,
• P. putida


  has been associated with catheter-related sepsis in patients with cancer
• P. fluorescens


  isolation of _______ from blood culture bottles in asymptomatic patients has been responsible for clusters of pseudobacteremia, probably related to contaminated catheters and catheter-related devices.
• Gelatin Hydrolysis


  can be used to differentiate the two species from each other; P. putida is negative and P. fluorescens is positive.
• P. fluorescens and P. putida

  They are usually susceptible to the aminoglycosides, polymyxin, and piperacillin, but are resistant to carbenicillin and SXT
• Pseudomonas stutzeri


  a rare isolate and even rarer pathogen in the clinical pathogen
• P. stutzeri


  is usually easily recognizable because of its characteristic macroscopic appearance of wrinkled, leathery, adherent colonies that may produce a light-yellow or brown pigment
• P. stutzeri


  Isolates are ADH negative and starch hydrolysis positive

  
  

  has been reported to be responsible for diseases that include septicemia, meningitis in people with human immunodeficiency virus infection, pneumonia (especially in patients with CF and those who are immunocompromised), endocarditis, postsurgical wound infections, septic arthritis, conjunctivitis, and UTIs

  
  

  Isolates in vitro are usually susceptible to the aminoglycosides, SXT, ampicillin polymyxin, tetracyclines, fluoroquinolones, and third-generation cephalosporins (e.g., ceftazidime) but resistant to chloramphenicol and the first- and second-generation cephalosporins
• Pseudomonas mendocina


  found in soil and water but is rarely isolated from human specimens; when it is, it is often considered a contaminant
• P. mendocina


  produces nonwrinkled, flat colonies that may appear with a yellowish-brown pigment, smooth buttery appearance.

  - It is oxidase and ADH positive
• Pseudomonas pseudoalcaligenes and Pseudomonas alcaligenes

  often considered contaminants when isolated from clinical specimens
• Pseudomonas pseudoalcaligenes and Pseudomonas alcaligenes

  They are oxidase positive and biochemically negative in many tests for which other Pseudomonas spp. test positive.

  - They grow on MAC agar and are variable in the reduction of nitrates to nitrites or nitrogen gas.
• Pseudomonas luteola and Pseudomonas oryzihabitans

  These two pseudomonads are rarely isolated from humans but have been isolated from wounds, abscesses, blood cultures, peritoneal and chronic ambulatory peritoneal dialysis (CAPD) fluids, and other sources.
• Pseudomonas luteola and Pseudomonas oryzihabitans

  They have also been implicated in cases of peritonitis and possibly meningitis, although often in association with each other or with other bacteria
• Pseudomonas luteola and Pseudomonas oryzihabitans

  Both of these pseudomonads are gram-negative, nonfermentative, oxidase- negative bacilli. They are catalase positive and motile, oxidize glucose, grow on MAC agar, and often produce an intracellular nondiffusible yellow pigment. Both species typically produce wrinkled or rough colonies at 48 hours
• positive o-nitrophenyl-β d-galactopyranoside (ONPG) and esculin hydrolysis tests.


  P. luteola can be differentiated from P. oryzihabitans
• Acinetobacter species:


  are oxidase negative, catalase positive, and nonmotile
• Acinetobacter spp.


  produces purple pigment and grow well on MacConkey agar
• A. baumannii


  Most glucose-oxidizing nonhemolytic strains were previously identified as
• Acinetobacter lwoffi


  most non-glucose utilizing, nonhemolytic strains were designated as
• A. johnsonii, A. junii, A. radioresistens, A. schindleri, A. ursingii.

  Other species that do not utilize glucose include
• Acinetobacter haemolyticus.


  Most beta-hemolytic strains are identified as
• Acinetobacter spp. and Stenotrophomonas maltophilia


  are opportunistic pathogens
• Acinetobacter infections


  primarily affect patients with weakened immune systems and coexisting diseases.
• A. lwoffii


  much less virulent, and when isolated, it usually indicates contamination or colonization rather than infection.