The most common organism that causes the following condition is

The above image is that of cellulitis of the leg.Cellulitis is a non-suppurative, invasive infection of tissues, which is usually related to the point of injury.Typically caused by B haemolytic streptococci, staphylococci and Clostridium perfringens. Streptococci being the commonest.Necrotising fasciitis is mostly polymicrobialGas gangrene is caused by Clostridium perfringens.Ref: Bailey and love 27th edition PG: 48