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Bacillus species

Background:

>Bacillus species:
     1] Bacillus anthracis
     2] Bacillus cereus
     3] Bacillus subtilis

Bacillus species:  

  • Ubiquitous gram-positive, rod-shaped bacteria that can be obligate aerobes or facultative anaerobes, and test positive for the enzyme catalase. 
  • Bacillus are known to form intracellular inclusions of polyhydroxyalkanoates under certain environmental conditions.  
  • Two Bacillus species are considered medically significant: B. anthracis, which causes anthrax, and B. cereus, which causes a foodborne illness similar to that of Staphylococcus.  
  • B. subtilis: notable food spoiler, causing ropiness in bread and related food. 
  • Microscopic examination: Bacillus cells appear as rods, and a substantial portion usually contain an oval endospore at one end, making it bulge.

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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.

Bacillus anthracis:

Bacillus cereus and Bacillus subtilis:

  1. Clindamycin  600mg IV every 6 or 8 hours or 300mg orally four times daily 
  2. Levofloxacin 500mg – 750 mg IV/PO once daily
  3. Moxifloxacin 400mg orally/IV qd
  4. Ciprofloxacin 250-500 mg orally or 200-400mg IV  q12h.
  5. Clarithromycin 500mg po q12h
  6. Chloramphenicol 50-100 mg/kg/day in divided doses every 6 hours (Maximum daily dose is 4 grams e.g. 1 gram q6h)
  7. Linezolid 600 mg orally or IV q12h
  8. Daptomycin 4 – 6 mg/kg IV once daily.  NOT FOR PNEUMONIA
  9. Tigecycline 100 mg IV x 1, then 50 mg q12h
  10. Imipenem 500mg IV every 6 hours.
Bacillus species