Enterobacter Species

Enterobacter species

Background:

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Enterobacteriaceae (Gram Negative Bacilli)
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>Citrobacter species:
     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

Enterobacter:

Gram-negative, facultatively anaerobic, rod-shaped, non-spore-forming bacteria of the family Enterobacteriaceae. Also oxidase-negative, indole-negative, and urease-negative. The genus Enterobacter ferments lactose with gas production during a 48-hour incubation at 35-37°C in the presence of bile salts and detergents.
Several strains of these bacteria are pathogenic and cause opportunistic infections in immunocompromised (usually hospitalized) hosts and in those who are on mechanical ventilation.
The urinary and respiratory tracts are the most common sites of infection.
The genus Enterobacter is a member of the coliform group of bacteria. It does not belong to the fecal coliforms (or thermotolerant coliforms) group of bacteria, as does Escherichia coli, because it is incapable of growth at 44.5°C in the presence of bile salts.
Two clinically important species from this genus are
- E. aerogenes and
- E. cloacae.

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.

Piperacillin-tazobactam (Zosyn ®) 3.375 – 4.5 grams IV q6h +/- Aminoglycoside or Ciprofloxacin 400mg IV q12h (Severe/complicated: 400mg IV q8h)
Cefepime 2 grams IV every 8 hours
Meropenem 0.5 – 1 gram IV q8h (life-threatening infection -unlabeled use: 2 grams IV q8h)
Imipenem 500mg IV every 6 hours [Range: 250-1000 mg q6-8h]
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]