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Stenotrophomonas maltophilia

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
>Stenotrophomonas maltophilia (Initially classified as Pseudomonas maltophilia)led

Stenotrophomonas maltophilia

  • Aerobic, nonfermentative, Gram-negative bacterium.  Motile due to polar flagella.  S. maltophilia are catalase-positive, oxidase-negative (which distinguishes them from most other members of the genus) and have a positive reaction for extracellular DNase.
  • It is an uncommon bacterium and human infection is difficult to treat.
  • Initially classified as Pseudomonas maltophilia, S. maltophilia was also grouped in the genus Xanthomonas before eventually becoming the type species of the genus Stenotrophomonas in 1993.
  • S. maltophilia frequently colonizes breathing tubes such as endotracheal or tracheostomy tubes, the respiratory tract and indwelling urinary catheters. Infection is usually facilitated by the presence of prosthetic material (plastic or metal), and the most effective treatment is removal of the prosthetic material (usually a central venous catheter or similar device).
  • In immunocompetent individuals, S. maltophilia is a relatively unusual cause of pneumonia, urinary tract infection, or blood stream infection; in immunocompromised patients, however, S. maltophilia is a growing source of and latent pulmonary infections.
  • S. maltophilia colonization rates in individuals with cystic fibrosis have been increasing.

 

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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.  

  1. Bactrim  15 to 20 mg/kg/day (based on trimethoprim component)  IV, given in equally divided doses every 6 to 8 hours.
  2. Levofloxacin 750 mg IV/PO once daily
  3. Moxifloxacin 400mg orally/IV qd
  4. Ceftazidime 2 grams IVPB q8h
  5. Bactrim  15 to 20 mg/kg/day (based on trimethoprim component)  IV, given in equally divided doses every 6 to 8 hours  PLUS  Ceftazidime 2 grams IVPB q8h

Stenotrophomonas maltophilia