Pseudomonas aeruginosa

Pseudomonas aeruginosa

Background:
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Non-fermenting Gram-negative bacilli   
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[cannot catabolize glucose and therefore are not able to ferment. Non-spore forming.]
>Acinetobacter baumannii
>Achromobacter xylosoxidans
>Bordetella pertussis
>Burkholderia species:
     1] Burkholderia cepacia (also known as Pseudomonas cepacia) –  important
            pathogen of pulmonary infections in people with cystic fibrosis.
     2] Burkholderia pseudomallei (also known as Pseudomonas pseudomallei) 
>Elizabethkingia meningoseptica (Previously Chryseobacterium meningosepticum)
>Moraxella catarrhalis (formerly known as Branhamella catarrhalis)
>Pseudomonas aeruginosa Led
>Stenotrophomonas maltophilia (Initially classified as Pseudomonas maltophilia)

Pseudomonas aeruginosa:  

  • Gram-negative, aerobic (considered by many as a facultative anaerobe), coccobacillus bacterium that secretes a variety of pigments, including pyocyanin (blue-green), pyoverdine (yellow-green and fluorescent), and pyorubin (red-brown). 
  • Found in soil, water, skin flora, and most man-made environments (found on and in medical equipment, including catheters, causing cross-infections in hospitals and clinics). 
  • The organisms versatility enables it to infect damaged tissues or those with reduced immunity and symptoms of infection include generalized inflammation and sepsis.
  • An opportunistic human pathogen.

 

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Therapy:
Important considerations:  The choice of an agent should be based on local antimicrobial sensitivities, site of infection, cost, and comorbid conditions.   Generally, the most common agents/regimens are listed first.   Listed dosages may need to be adjusted for renal dysfunction.  

Therapy for Pseudomonas should be guided by susceptibility testing.  

  1. Piperacillin-tazobactam (Zosyn ®)  3.375 to 4.5  grams IV q6h
  2. Ceftazidime 2 grams IVPB q8h
  3. Cefepime 2 grams IV every 8-12 hours
  4. Ciprofloxacin  400mg IV q8h
  5. Ciprofloxacin  400mg IV q8h PLUS [Ceftazidime 2 grams IVPB q8h OR Cefepime 2 grams IV every 8-12 hours]
  6. Imipenem 500mg IV every 6 hours [Range: 250-1000 mg q6-8h]
  7. Meropenem 0.5 – 1 gram IV q8h  (life-threatening infection -unlabeled use: 2 grams IV q8h)
  8. Carbapenemase producing strains –
    • Colistimethate (colistin base): 2.5 – 5mg/kg/day in 2-4 divided doses. Max 5 mg/kg/day   PLUS   [ Meropenem 1 gram IV q8h  OR  Imipenem 500mg IV every 6 hours [Range: 250-1000 mg q6-8h]
    • Colistimethate (colistin base): 2.5 – 5mg/kg/day in 2-4 divided doses. Max 5 mg/kg/day   PLUS  Rifampin
    • Colistimethate (colistin base): 2.5 – 5mg/kg/day in 2-4 divided doses. Max 5 mg/kg/day   PLUS Ceftazidime

 

Antibiotics used in combination with agents listed above for resistant strains or severe disease – Examples include – [Cefepime + gent, tobra, or amikacin];  [Ceftazidime  + gent, tobra, or amikacin];   [Zosyn ® +  gent, tobra, or amikacin]; …. :

  1. Gentamicin 1 to 2.5 mg/kg IV q8-12h or consider high-dose extended-interval dosing:  5 to 7 mg/kg q24-48h.  Adjust regimen based on estimated clearance.
  2. Tobramycin 1 to 2.5 mg/kg IV q8-12h or consider high-dose extended-interval dosing:  5 to 7 mg/kg q24-48h.  Adjust regimen based on estimated clearance.
  3. Amikacin 5 to 7.5 mg/kg IV q8h or consider high-dose extended-interval dosing: 15-20 mg/kg q24-48h.  Adjust regimen based on estimated clearance.
  4. Aztreonam: 1-2 grams IV q8-12h.  Severe/Life-threatening: 2 grams IV q6-8h.
Pseudomonas aeruginosa