Citrobacter species

Background:

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Enterobacteriaceae  (Gram Negative Bacilli)  
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>Citrobacter species: led
     1] Citrobacter koseri
     2] Citrobacter freundii
>Enterobacter species
     1] Enterobacter cloacae,
     2] Enterobacter aerogenes)
>Escherichia coli
>Klebsiella species:
     1] Klebsiella ozaenae
     2] Klebsiella pneumoniae
     3] Klebsiella rhinoscleromatis
>Morganella species 
     1] (Morganella morganii)
>Proteus species:
     1] Proteus mirabilis
     2] Proteus vulgaris
>Providencia species:
     1] Providencia_rettgeri
     2] Providencia stuartii
>Salmonella species:
     1] Salmonella enteritidis
     2] Salmonella typhi
     3] Other
>Serratia marcescens
>Shigella species:  
     1] Shigella dysenteriae (serogroup A)
     2] Shigella flexneri
     3] Shigella boydii
     4] Shigella sonnei
     5] Other

Citrobacter:

  • Gram-negative coliform bacteria in the Enterobacteriaceae family. Citrobacter species are differentiated by their ability to convert tryptophan to indole, ferment lactose, and use malonate.
  • The species C. amalonaticus, C. koseri, and C. freundii can use citrate as a sole carbon source.
  • Ubiquitous: found almost everywhere in soil, water, wastewater, etc. Also found in the human intestine.
  • Rarely the source of illnesses, except for infections of the urinary tract and infant meningitis and sepsis.
  • C. freundii strains have inducible ampC genes encoding resistance to ampicillin and first-generation cephalosporins. In addition, isolates of Citrobacter may be resistant to many other antibiotics as a result of plasmid-encoded resistance genes.

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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.  

Citrobacter is usually resistant to multiple antibiotics due to plasmid-encoded resistance genes.

  1. Cefpodoxime (Vantin ®) 200-400 mg orally twice daily   [3rd generation ceph]
  2. Ceftriaxone 1-2 grams IV q24h  (range: 1-2 grams q12-24h)
  3. Ciprofloxacin  400mg IV q12h (Severe/complicated: 400mg IV q8h)
  4. Cefepime 1-2 grams IV every 8-12 hours
  5. Imipenem 500mg IV every 6 hours [Range: 250-1000 mg q6-8h]
  6. Meropenem 1 gram IV q8h
  7. Doripenem 500 mg IV q8h

Disclaimer

The authors make no claims of the accuracy of the information contained herein; and these suggested doses are not a substitute for clinical judgment. Neither GlobalRPh Inc. nor any other party involved in the preparation of this program shall be liable for any special, consequential, or exemplary damages resulting in whole or part from any user’s use of or reliance upon this material.PLEASE READ THE DISCLAIMER CAREFULLY BEFORE ACCESSING OR USING THIS SITE. BY ACCESSING OR USING THIS SITE, YOU AGREE TO BE BOUND BY THE TERMS AND CONDITIONS SET FORTH IN THE DISCLAIMER. Read the disclaimer