Pathogenesis of s aureus Stage I: encounter-humans are major reservoir for s, aureus Colonize nose and are found in about 30% of individuals Transiently found on skin, oropharynx, and feces Transmitted via e Hand contact Aerosols from pneumonia patients BIOL 533 7 Lecture 10
BIOL 533 7 Lecture 10 Pathogenesis of S. aureus • Stage I: encounter—humans are major reservoir for S. aureus – Colonize nose and are found in about 30% of individuals – Transiently found on skin, oropharynx, and feces – Transmitted via: • Hand contact • Aerosols from pneumonia patients
Pathogenesis of s aureus Stage I, continued Certain occupations are more prone to colonization Physicians, nurses, hospital workers Certain classes of patients are more prone to colonization DiabeticS, hemodialysis patients, and drug abusers BIOL 533 Lecture 10
BIOL 533 8 Lecture 10 Pathogenesis of S. aureus • Stage I, continued – Certain occupations are more prone to colonization • Physicians, nurses, hospital workers – Certain classes of patients are more prone to colonization • Diabetics, hemodialysis patients, and drug abusers
Pathogenesis of s aureus Stage II: entry--not normally through unbroken skin Can enter if large numbers have accumulated through poor hygiene BIOL 533 Lecture 10
BIOL 533 9 Lecture 10 Pathogenesis of S. aureus • Stage II: entry—not normally through unbroken skin – Can enter if large numbers have accumulated through poor hygiene
Pathogenesis of s aureus Stage III: spread and multiplication Survival depends on ● Number of organisms ● Site involved Speed with which inflammatory response is mounted Immunological competence of host If inoculum is small and host immunologically competent: infection normally defeated BIOL 533 Lecture 10
BIOL 533 10 Lecture 10 Pathogenesis of S. aureus • Stage III: spread and multiplication – Survival depends on • Number of organisms • Site involved • Speed with which inflammatory response is mounted • Immunological competence of host – If inoculum is small and host immunologically competent: infection normally defeated
Pathogenesis of s aureus Stage IV: damage Local infection leads to formation of abscess (collection of pus) In skin boils or furuncles Interconnected abscesses are called carbuncles May also spread in subcutaneous or submucosal tissues--cellulitis BIOL 533 Lecture 10
BIOL 533 11 Lecture 10 Pathogenesis of S. aureus • Stage IV: damage – Local infection leads to formation of abscess (collection of pus) • In skin, boils or furuncles • Interconnected abscesses are called carbuncles – May also spread in subcutaneous or submucosal tissues—cellulitis