Skin Infections Flashcards
What is the purpose of skin?
-Protect underlying tissues from microbial colonization
How is the skin protected?
- keratin
- Cell shedding of epidermis
- Antimicrobial chemicals in sweat
- Acid sebum
What kind of bacteria would you expect to fin in sebaceous, moist, and dry sites?
Sebaceous: Forehead and back, hair follicles (propionibacterium)
Moist: Navel groin foot (corynebacterium)
Dry: staph, aciinetobacter and micrococcus
What is acne caused by?
Most common skin condition in the developed world
- chronic inflammation
- caused by excess sebum and propionibacterium acnes
What is sebum?
Excretion from glands supplies for the bacteria to grow on your face as bacteria
What are characteristics of propionibacterium acnes?
Gram+ Anaerobic Rod Linked to acne Commensal part of skin flora In follicles lines on dead material
What do surgical wounds do for microbes?
Introducing indigenous microbes to a new tissue environment and cause an infection
What are chronic skin wound infections?
From predisposing conditions
What are acute skin wound infections?
From cuts/bites or from tubes inserted into patients
What are characteristics of staphylococcus epidermis?
gram+
Normal human skin flora
Cocci
Facultative anaerobic (has the power to be anaerobic)
What can contact diseases be caused by?
Bacterial species that originate externally
-staphylococcus aureus infections
What are characteristics of staphylococcus aureus?
Gram+ Cocci Commensal Opportunistic Skin or upper respiratory tract
What are the toxins associated with S. aureus?
Impetigo: highly contagious blisters
Scalded Skin Syndrome: Epidermis peels off
Toxic Shock Syndrome: Sunburn like rash, peeling skin
What are the skin diseases that streptococcus progenies cause?
Can be mild to severe and classified by their hemolytic action and carbohydrate profile
- Group A is hemolytic on blood agar
- Pathogenicity proceeds by attaching to cells and secreting toxins
- serotypes are identified by M protein typing
What are characteristics of streptococcus pyogenes?
Gram+
Non motile
Cocci
Pathogenic on skin
How many people die from Group A strep annually? (GAS)
500,000 globally
How does GAS get transferred from one person to the next?
Direct contact with the mucus from the nose or throat of infected individuals or through contact with infected wounds on the skin
-also spread via asymptomatic carriers
What is the most common GAS infection?
Strep throat
-can also cause a version of impetigo
What are 3 severe forms of GAS infection?
Cellulitis: rapidly enlarging skin lesions, fever, shaking
Streptococcal toxic shock syndrome: Similar to TTS
Necrotizing Fasciitis: Flesh eating- disease that destroys musclee fat and soft skin tissue
What can also lead to skin infections?
Traumatic wounds to the skin surface can lead to localized infection
What are characteristics of pseudomonas?
Gram- Rod Commensal Opportunistic Polar Flagella May produce a fluorescent pigment
What is leprosy?
Chronic systemic infection that dulls nerves, causing deformities due to lack of pain sensation
What causes leprosy?
Mycobacterium leprae
What are the consequences of leprosy?
Disfigures skin and bones, twists limbs and causes claw hands
Who is susceptible to leprosy?
95% of the population is naturally immune
-still present in Texas and Louisiana due to contact with armadillos
How is leprosy treated?
Multidrug therapy
-took so long because it is really hard to culture in the lab
What are characteristics of mycobacterium leprae?
Aerobic
Bacillus
Pleomorphic: takes on different shapes within tissues of the body
