Your history can help to narrow down the possible causes of cellulitis the following are a list of bacteria that are associated with specific parts of the history.

  • Diabetes: Staphylococcus aureus, group B streptococci, anaerobes, gram-negative bacilli
  • Cirrhosis: Campylobacter fetus,coliforms, Vibrio vulnificus,Capnocytophaga canimorsus
  • Neutropenia: Pseudomonasaeruginosa
  • Human bite: Eikenella corrodens
  • Cat bite: Pasteurella multocida
  • Dog bite: P. multocida,C. canimorsus
  • Rat bite: Streptobacillus moniliformis
  • Hot tub exposure: P. aeruginosa
  • Fresh water laceration: Aeromonas hydrophila
  • Fish tank exposure: Mycobacterium marinum
  • IV drug use: MRSA, P. aeruginosa

Always be cognoscent not to miss necrotizing fasciitis, physical findings that should increase your suspicion are pain out of proportion to exam, systemic symptoms including tachycardia, fever, hypotension, bullae and crepitus (however bullae only occur in 45% of cases and crepitus only occurs in 13% of cases).  If there is a concern about necrotizing fasciitis then calculate a LRINEC score (CRP, WBC, Hb, Na, Cr, Glu).  The initial study using the LRINEC score was published in 2004.