1/26/2016 Coagulase-negative staphylococci Staphylococcal Skin Infections urface of catheter Staphylococcus aureus -Can survive for months on surfaces -Larger genome than 5.epidermidis (300,000 bp) Coagulase-positive -May produce damaging toxins and cause sepsis Avoids host defenses in the skin 四 6) 四m Secretes proteins and toxins that ll phagocytic cells MRSA strains are antibiotic-resistant ·methicillin-resistant三.cres is beginning to appear. the biofilm. Staphylococcal Skin Infections Often transported from nasal passages to the skin where it can enter through openings such as the hair follicles Folliculitis:infections of the hair follicles Sty:folliculitis of an eyelash Furuncle (boil):a type of abscess;localized region of pus surrounded by inflamed tissue antibiotics do not penetrate well making it difficult to treat Carbuncle:damage and inflammation of deep ading furuncle group of Impetigo:crusting (nonbullous)sores, spread by autoinoculation 61/26/2016 6 Coagulase-negative staphylococci Biofilm Surface of catheter Biofilm Catheter surface with adhering bacteria. Biofilm, light green, is beginning to appear. Most of the bacteria producing the slime are not visible under the biofilm. Staphylococcal Skin Infections • Staphylococcus aureus – Carried in the nasal passages of 20% of the population py y y ermanently; 60% carry it transiently – Can survive for months on surfaces – Golden-yellow colonies; pigment protects against sunlight and killing by neutrophils – Larger genome than S. epidermidis (300,000 bp) – Coagulase-positive – M d d i i d i May produce damaging toxins and cause sepsis – Avoids host defenses in the skin • Secretes proteins and toxins that kill phagocytic cells – MRSA strains are antibiotic-resistant • methicillin-resistant S. aureus Staphylococcal Skin Infections Often transported from nasal passages to the skin where it can enter through openings such as the hair follicles • Folliculitis: infections of the hair follicles • Sty: folliculitis of an eyelash • Furuncle (boil): a type of abscess; localized region of pus surrounded by inflamed tissue - antibiotics do not penetrate well making it diffi lt t t t difficult to treat • Carbuncle: damage and inflammation of deep tissue from a spreading furuncle, group of hair follicles are infected • Impetigo: crusting (nonbullous) sores, spread by autoinoculation