bacterial skin infections are important to recognize because we have the means to eradicate almost all of them primary skin infections are mainly caused by staphylococci or streptococci staphylococci infections present as furuncles and carbuncles superficial folliculitis impetigo or rarely the scalded skin syndrome streptococcal infections present as impetigo ecthyma erysipelas or cellulitis corynebacteria causes erythrasma trichomycosis or pitted keratolysis gram negative primary skin infections although uncommon may occur bacterial cultures are generally necessary for diagnosis secondary bacterial infections of pre existing wounds burns dermatitic skin or retention cysts are common events.