The first two are the classics, defined by a 16-patient case series:
- Type I: polymicrobial infections caused by Enterobacteraciae, non-Group A streptococci, and anaerobes
- Type II: monomicrobial infections, usually Gram-positive, and usually Group A streptococci
The next two were added later on:
- Type III: monomicrobial Gram-negative infections, generally caused by water-associated Vibrio vulnificans or Aeromonas hydrophila
- Type IV: fungal, caused by Candida species, and exceedingly rare
I’ll cite this review for those four, although there appears to be some disagreement on what constitutes Type III; many other articles refer to Type III as gas gangrene caused by Clostridium species. In this matter, I’ll defer to Mandell: it says Vibrio, so I’ll say Vibrio.