Skin Infections

Question 1

What is the purpose of skin?

Answer 1

-Protect underlying tissues from microbial colonization

Question 2

How is the skin protected?

Answer 2

• keratin
• Cell shedding of epidermis
• Antimicrobial chemicals in sweat
• Acid sebum

Question 3

What kind of bacteria would you expect to fin in sebaceous, moist, and dry sites?

Answer 3

Sebaceous: Forehead and back, hair follicles (propionibacterium)

Moist: Navel groin foot (corynebacterium)

Dry: staph, aciinetobacter and micrococcus

Question 4

What is acne caused by?

Answer 4

Most common skin condition in the developed world

• chronic inflammation
• caused by excess sebum and propionibacterium acnes

Question 5

What is sebum?

Answer 5

Excretion from glands supplies for the bacteria to grow on your face as bacteria

Question 6

What are characteristics of propionibacterium acnes?

Answer 6

Gram+
Anaerobic
Rod
Linked to acne
Commensal part of skin flora
In follicles lines on dead material

Question 7

What do surgical wounds do for microbes?

Answer 7

Introducing indigenous microbes to a new tissue environment and cause an infection

Question 8

What are chronic skin wound infections?

Answer 8

From predisposing conditions

Question 9

What are acute skin wound infections?

Answer 9

From cuts/bites or from tubes inserted into patients

Question 10

What are characteristics of staphylococcus epidermis?

Answer 10

gram+
Normal human skin flora
Cocci
Facultative anaerobic (has the power to be anaerobic)

Question 11

What can contact diseases be caused by?

Answer 11

Bacterial species that originate externally

-staphylococcus aureus infections

Question 12

What are characteristics of staphylococcus aureus?

Answer 12

Gram+
Cocci
Commensal
Opportunistic
Skin or upper respiratory tract

Question 13

What are the toxins associated with S. aureus?

Answer 13

Impetigo: highly contagious blisters

Scalded Skin Syndrome: Epidermis peels off

Toxic Shock Syndrome: Sunburn like rash, peeling skin

Question 14

What are the skin diseases that streptococcus progenies cause?

Answer 14

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

Question 15

What are characteristics of streptococcus pyogenes?

Answer 15

Gram+
Non motile
Cocci
Pathogenic on skin

Question 16

How many people die from Group A strep annually? (GAS)

Answer 16

500,000 globally

Question 17

How does GAS get transferred from one person to the next?

Answer 17

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

Question 18

What is the most common GAS infection?

Answer 18

Strep throat

-can also cause a version of impetigo

Question 19

What are 3 severe forms of GAS infection?

Answer 19

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

Question 20

What can also lead to skin infections?

Answer 20

Traumatic wounds to the skin surface can lead to localized infection

Question 21

What are characteristics of pseudomonas?

Answer 21

Gram-
Rod 
Commensal
Opportunistic
Polar Flagella
May produce a fluorescent pigment

Question 22

What is leprosy?

Answer 22

Chronic systemic infection that dulls nerves, causing deformities due to lack of pain sensation

Question 23

What causes leprosy?

Answer 23

Mycobacterium leprae

Question 24

What are the consequences of leprosy?

Answer 24

Disfigures skin and bones, twists limbs and causes claw hands

Question 25

Who is susceptible to leprosy?

Answer 25

95% of the population is naturally immune

-still present in Texas and Louisiana due to contact with armadillos

Question 26

How is leprosy treated?

Answer 26

Multidrug therapy

-took so long because it is really hard to culture in the lab

Question 27

What are characteristics of mycobacterium leprae?

Answer 27

Aerobic
Bacillus
Pleomorphic: takes on different shapes within tissues of the body