Case 158. Panel: Staphylococcal infection
         
   
Normal flora, folliculitis, secondary infection, S-TEN, pyoderma
   
         
   
Key words : Staphylococcus aureus, folliculiitis, S-TEN, pyoderma
   
     
 
     
Panel 1
Normal flora in the dilated hair follicle of the facial skin (HE). Staphylococcal colonization is evident in the hair follicle of the perinasal skin.
  Panel 2
Normal flora in the dilated hair follicle of the facial skin (Gram). MRSA and MSSA are indistinguishable in H&E or Gram preparations.
     
 
     
Panel 3
Acute folliculitis in the back (58 y-o M), accompanying intradermal abscess (HE). Intradermal abscess is caused by destructive proliferation of S. aureus.
  Panel 4
Acute folliculitis in the back (58 y-o M), accompanying intradermal abscess (Gram). Infection of Gram-positive cocci around the hair follicle is called furuncle or boil.
     
 
     
Panel 5
Staphylococcal colonization on the surface of the lip mucosa (HE). Epidermoadhesive pattern of colonization is characteristic.
  Panel 6
Secondary infection of S. aureus in the cornified layer on the surface of pyogenic granuloma (HE). S. aureus often grows on the surface of a variety of skin lesions of either polypoid or ulcerated type.
     
 
     
Panel 7
Staphylococcal scaleded skin syndrome (SSSS). The perioral skin of the newborn shows diffuse exfoliation (gross findings). Histologically, subcorneal acantholysis and bulla formation are seen. Exfoliative toxins, an etiologic factor, are secreted by S. aureus at the site of local infection.
  Panel 8
Toxic epidermal necrolysis (TEN) in a 50 y-o female (HE). The necrotic epidermis is easily peeled off (Nikolsky phenomenon). Life-threatening TEN is most often caused by drug allergy. No bacteria are seen in the lesion.
     
 
     
Panel 9
Staphylococcal epidermolytic toxin syndrome (generalized bullous impetigo) in a 68 y-o male (HE). Infection of Gram-positive cocci is seen along the pustule formed in the epidermis. This condition has erroneously been called as staphylococcal TEN.
  Panel 10
S. aureus in the lesion of pyoderma (unclear in H&E preparation) is positively stained by 1:500 diluted patient's own serum (indirect immunoperoxidase). Cutaneous staphylococcal infection unrelated to the hair follicle is called exthyma. S. aureus is pathogenic, but S. epidermidis is non-pathogenic.