Final Exam: Skin infections Flashcards
Lesion
change or abnormality in the skin that is usually in a defined area; may be harmless or serious
Primary lesion
associated with a specific disease process; useful for diagnosis
Secondary lesions
less obviously associated with a specific disease; may develop from a primary lesion
Rash
widespread eruption of lesions; may be symptomatic or asymptomatic
Propionibacterium acnes
Acne
Staphylococcus aureus and MRSA
Impetigo, cellulitis, folliculitis, scalded skin syndrome
Streptococcus pyogenes
Impetigo, cellulitis, necrotizing fasciitis, streptococcal toxic shock syndrome
Clostridium perfringens
Gas gangrene
Propionibacterium acnes: Mechanism of action
Sebum and dead skin cells block pores
P. acnes proliferative in clogged pores
Inflammatory response
Staphylococcal Impetigo: signs/symptoms
Superficial pus-filled vesicles
Reddened skin (face, lips, or extremities)
Itchy vesicles can rupture and ooze
Crust over into honey-colored lesions
Staphylococcal Impetigo: Chracteristics, Transmission, Treatment
Highly contagious, Secondary bacterial infections possible
Direct contact, Contaminated fomites, Childcare centers
Topical antibiotics
Staphylococcal Erysipelas: Progression and symptoms
Impetigo spreads to surrounding skin and lymph nodes, Extensive inflammation and pain
Fever, Chills, Leukocytosis, If untreated, erysipelas may be fatal
Cellulitis: Signs and symptoms
Infection of lower dermis, subcutaneous fat
Red, swollen, and painful skin
Fever
Leukocytosis and/or lymphangitis
Legs are the most commonly infected
May spread to lymph nodes and bloodstream
Potentially fatal if not treated
MRSA treatment and prevention
Vancomycin, rifampin, tetracyclines
Resistance emerging
Vancomycin-intermediate S. aureus (VISA)
Vancomycin-resistant S. aureus (VRSA)
Healthcare workers carefully follow hand-washing and antisepsis precautions
Staphylococcal scalded skin syndrome
Skin apprears to have burned by boiling water
Exfolative toxins produced by S. aureus
Toxins causes the outer layer of epidermal cells to peel in sheets
Toxins may be carried by the bloodstream to other area
Streptococcus pyogenes
Gram positive cocci with a beads on a string appearance
Catalase negative
Only some species are true pathogens, most are normal flora in many parts of the body
“Pyogenes” comes from the Greek word for “pus-forming”
Often causes pus filled lesions
Can also cause:
Impetigo
Cellulitis
Streptococcus pyogenes: complications
Necrotizing fasciitis
Streptococcal Toxic Shock Syndrome
S. pyogenes can cause streptococcal toxic shock syndrome
Bacterial toxins are released into the bloodstream
Causes drop in blood pressure and organ failure
May manifest with a skin rash
Pseudomonads can
cause opportunistic infections as well as serious wound infections
Pseudomonas bacteria
Gram-negative rods
Normal skin residents
Abundant in soil and water
Metabolize a wide range of substances
Can thrive on plants and floral vase water
Ability to break down certain detergents
Increasingly resistant to many antibiotics
Pseudomonas aeruginosa
Most medically relevant of the pseudomonads
Opportunistic pathogen – normal immunecompetent hosts are usually not affected
Ability to form biofilms
Pseudomonads: Burn and other skin wound patients
~60% of burn patients develop P. aeruginosa infections
As skin wounds heal, the bacteria can grow underneath scabs
P. aeruginosa wound treatment
Meticulous wound care
Antibiotics
Protective creams that contain silver
Debridement of affected scabs or tissue to remove bacteria
Some P. aeruginosa strains make
pyocyanin-Greenish-blue pigment
Otitis Externa (Swimmer’s Ear)
Improperly maintained saunas, pools, or hot tubs
Allows P. aeruginosa to thrive
Gas Gangrene: bacteria
Clostridium perfringens
Anaerobic Gram-positive; endospore-forming rods
Naturally live in the soil
Gas gangrene
C. perfringens infect deep wounds
Release foul-smelling gases emitted as the bacteria destroy infected tissues
If untreated, progresses to shock, kidney failure, and death
Gangrene
Blood vessels are damaged
Decreased blood flow to tissues
Tissues starve for oxygen and nutrients
Necrosis (tissue death)
Affects the extremities
