A Skin Diseases and Eye Infections - Chapter 21

pyoderma

pus filled

Staphylococcal infections

-S. aureus invasion through folliculitis (hair follicle/pimple)

-sty: eyelash

-boil (furnacle): deeper pus-pus filled infection

-carbuncle: further infection

-S. aureus strains: prevent mvmt of phagocytic cells to site of infection, kill macrophage with leukocidin

-coagulase (+)

-peptidoglycan layer resists digestion by lysozyme

-can get repeated infections

-act as superantigen in some cases

-hospital personnel: asymptomatic carriers

Impetigo

-staphylococci/staphylococcus pyogenes: pyoderma lesions (strep throat)

- sometimes both make mixed infection

Scalded skin syndrome

- S. aureus caused by 2 different exotoxins

--exfoliative toxin A: produced from a plasmid

--exfoliative toxin B: carried on the chromosome, carried in circulation (all areas of the skin can be damaged)

---pemphigus neonatorum: can cause impetigo on newborn

Toxic Shock Syndrome (TSS)

-may lead to shock and organ failure (can be life threatening)

-TSS toxin (TSST-1): released into circulation

--acting as a superantigen

Streptococcal Infections

-Streptococcus pyogenes referred to as group A Streptococci (GAS)

-erythrogenic toxin: (carried on prophage) and causes "Strep Throat" or complication "scarlet fever"

-produce virulence factors: hemolysins, streptolysin, M protein, a capsule, streptokinase, hyaluronidase, and deoxyribonucleases

-Rheumatic Fever: immune system complication

- S. pyogenes also involve: Erysipelas, Necrotizing Fasciitis and Streptococcal TSS

Acne

-infection

-Propionibacterium acnes

-sebaceous glands secrete more oil (nutrients) onto skin, organisms multiply to a greater degree

-over growth--> clogged and inflamed skin pores--> tissue destruction

Pseudomonas dermatitis

-Pseudomonads, often Pseudomonas aeruginosa

--highly resistant to antibiotics and disinfectants

--makes several exotoxins,

--found growing in a biofilm making endotoxins

--frequent cause of infections in burn patients

Ophthalmia neonatorum

-Neisseria gonorrhoeae or Chlamydia trachomatis

--present in birth canal can infect baby

--conjunctivitis (pink eye) of newborn

-treatments: silver nitrate or tetracycline

"Pink Eye"

-bacterial conjunctivitis caused by: Staphylococcus, Streptococcus, Neisseria, Haemophilus influenza, and Pseudomonas

-treatment: sulfonamide ointment

Trochoma

-chlamydia trachomatis: swollen conjunctiva

-can lead to blindness if left untreated

-trichiasis: eyelashes turn inward (trichiasis), can scar the cornea

-secondary infections common