skin infections

Question 1

what are the features of S. Aureus?

Answer 1

• gram +ve
• colonisation in nose, axilla, groin
• most common cause of skin infections

Question 2

how does S Aureus effect the dermis/epidermis?

Answer 2

• impetigo (infection of subcorneal of epidermis)
• folliculitis (infection of mouth of hair follicle)
• ecthyma (infection of full thickness of epidermis)
• boils (abscess of hair follicle)
• carbuncle (abscess of several adjacent follicles)

Question 3

What are the diseases caused by Staph Aureus? Via which toxin?

Answer 3

• Staphylococcal Scalded Skin Syndrome (Exfoliative toxin)
• toxic shock syndrome (toxic shock syndrome toxin)
• food poisoning (enterotoxin)
• necrotising soft tissue infections (panton Valentine Leucocidin VF)

Question 4

how do you treat all of these diseases?

Answer 4

• antibiotics

Question 5

What is Treoponema pallidum?

Answer 5

• cause of syphilis

- syphilis can be vertically transmitted and cause congential syphilis

Question 6

what are the features of the herpes simplex virus?

Answer 6

• members of human herpes virus (HHV) family
• DNA viruses
• Type 1: causes oral infections
• Type 2: causes genital infections
• transmission by direct contact

Question 7

what are the stages of syphilis?

Answer 7

• primary: painless ulcers at site of inoculation
• secondary: disseminatted infection with rash, lymphadenopathy
• latent: asymptomatic period
• tertiary: skin (gummatous skin lesions, bone lesions), neurological and vascular manifestations

Question 8

what are the clinical features of HSV?

Answer 8

• painful vesiclar rash (heals over 2-4 weeks)
• eczema herpeticum
• herpes encephalitis

Question 9

what is the treatment of HSV?

Answer 9

• no vaccine

- outbreaks treated with anti-viral medication e.g. acyclovir

Question 10

what is the target cell, disease caused and site of latency of HHV-2?

Answer 10

• muco-epithelial
• oro-genital herpes
• neuron

Question 11

what is the target cell, disease caused and site of latency of HHV-1?

Answer 11

• muco-epithelial
• chicken pox, shingles
• neuron

Question 12

what is VZV?

Answer 12

• varicella zoster virus

- another human herpes virus

Question 13

what is the primary infection with VZV?

Answer 13

• causes chicken pox
• prodrome of fever and malaise
• followed by development of widespread vesicular rash
• usually lasts around 2 weeks and then becomes latent
• can reactivate shingles

Question 14

what is herpes zoster or shingles?

Answer 14

• reactivation of VZV and a painful vesicular rash appears along course of a dermatome
• usually heals in 2-4 weeks
• can be consequences if CN V1 damaged

Question 15

what are the features of Trichophytum?

Answer 15

• common cause of superficial infection
• dermatophte
• “tinea” followed by body part
  e. g. Tinea capitis

Question 16

what is a dermatophyte?

Answer 16

• type of fungus that particularly affects parts of body that have keratin

Question 17

what are the clinical mainfestations of trichophytum?

Answer 17

• erythromatous scaly rash on skin/scalp
• discoloured
• crumbly nails

Question 18

how is trichophytum treated?

Answer 18

• topical or systemic anti-fungals

e. g. Terbinafine

Question 19

what is scabies?

Answer 19

skin infectation by mite Sarcoptes scabei

Question 20

what is the pathogenesis of scabies?

Answer 20

• mite burrows into surface of skin
• exposure to mite faeces and eggs cause a delayed-type allergic reaction
• results in widespread eczematous rash
• occurs around 4 weeks after 1st infection
• itchy
• secondary bacterial infection common

Question 21

where are the burrow sites usually?

Answer 21

• genital regions
• nipples
• wrists
• finger webs
• instep of feet
• axilla

Question 22

how do you treat scabies?

Answer 22

topical systemic insecticides