Microbiology of Skin

Question 1

Gram positive cocci in clusters

Answer 1

Staphylococcus sp.

Question 2

What distinguishes staph aureus from other staph species (other than gold colour)?

Answer 2

It produces coagulase

Question 3

What toxins do some staph strains produce?

Answer 3

Enterotoxin (food poisoning), SSST (staph scalded skin syndrome toxin) and PVL (Panton valentine leukocidin)

Question 4

Gram positive cocci in chains

Answer 4

Streptococcus sp.

Question 5

How are strep sp. classified?

Answer 5

Haemolysis (Beta-haemylytics then further classified as group A or B)

Question 6

What are 2 important alpha-haemolytic strep sp.?

Answer 6

Strep pneumonia and strep viridian’s

Question 7

What is an important non-haemolytic strep?

Answer 7

Enterococcus sp. (commensals of bowel)

Question 8

What components of the skin fight bacterial infection?

Answer 8

Skin barrier; dry surface (cause desiccation); sebum inhibits growth; competitive bacteria

Question 9

What are 3 main commensal bacteria of the skin?

Answer 9

Staphylococcus epidermis; Corynebacterium sp. (“diphtheroids”) and Proprionobacterium sp.

Question 10

What antibiotic is used for staph aureus and strep pyogenes?

Answer 10

Flucoxacillin

Question 11

What is necrotising fasciitis?

Answer 11

Bacterial infection spreading along fascial planes below skin surface → rapid tissue destruction

Question 12

What are the 2 types of necrotising fasciitis?

Answer 12

Type 1 – mixed anaerobes & coliforms, usually post-abdominal surgery and Type II – Group A Strep infection

Question 13

Tina =

Answer 13

Ringworm

Question 14

Dermatophyte infection aka

Answer 14

Fungal infection (Ringworm)

Question 15

What is the pathogenesis of dermatophyte infection?

Answer 15

1. Fungus enters abraded or soggy skin
2. Hyphae spread in stratum corneum
3. Infects keratinised tissues only (skin, hair, nails)
4. Increased epidermal turnover causes scaling
5. Inflammatory response provoked (dermis)
6. Hair follicles and shafts invaded
7. Lesion grows outward and heals in centre, giving a “ring” appearance

Question 16

What are 3 main causal organisms for fungal infections?

Answer 16

Trichophyton rubric (>70%); Trichophyton mentagraphytes (>20%) and Microsporum canis

Question 17

What investigations should be done for fungal infections?

Answer 17

Wood lamp and scrapings/clippings for microscopy and culture

Question 18

What is the treatment for small areas of ringworm?

Answer 18

Clotrimazole (canestan) cream or similar, topical nail paint (amorolfine)

Question 19

Where do candida infections occur?

Answer 19

Skin folds where area is warm and mois

Question 20

What is the causal organism of scabies?

Answer 20

Sarcoptes scabiei

Question 21

What is the treatment of scabies?

Answer 21

Malathion lotion and benzyl benzoate (avoid in kiddies)

Question 22

What is the treatment of lice?

Answer 22

Malathion

Question 23

Which virus is responsible for chickenpox and shingles?

Answer 23

Varicella zoster

Question 24

What is Neonatal Varicella zoster virus and how can it be prevented?

Answer 24

Secondary to chickenpox in mother later in pregnancy, can be prevented with VZV immune globulin in susceptible women

Question 25

What kind of distribution does Shingles have?

Answer 25

Dermatomal

Question 26

What is pain associated with shingles for more than 4 weeks known as?

Answer 26

Post Herpetic Neuralgia

Question 27

What is ophthalmic zoster?

Answer 27

Shingles affecting there ophthalmic division of the trigeminal nerve

Question 28

Ramsay-Hunt Syndrome

Answer 28

A complication of shingles where the facial nerve is affected , causing vesicles and pain in auditory canal and throat

Question 29

Which virus causes primary gingivostomatitis?

Answer 29

Herpes simplex virus

Question 30

Which type of HSV normally causes oral lesions?

Answer 30

Type 1

Question 31

What is the treatment for HSV?

Answer 31

Aciclovir

Question 32

Erythema Multiforme

Answer 32

A hypersensitivity reaction usually triggered by infections, most commonly herpes simplex virus (HSV)

Question 33

What is the management of molluscs contagiousum?

Answer 33

It is self-limiting but takes months to disappear, so can be treated with local application of liquid nitrogen

Question 34

Which virus causes warts?

Answer 34

Human papilloma virus

Question 35

What is the treatment for warts?

Answer 35

Self-limiting, but can use topical salicylic acid

Question 36

Which types of HPV are most commonly associated with warts/verrucas?

Answer 36

Types 1-4

Question 37

Which types of HPV are most commonly associated with genital warts?

Answer 37

Types 6 and II

Question 38

Which types of HPV are most commonly associated with cervical cancer?

Answer 38

Types 16 and 18

Question 39

What is Herpangina and which virus causes it?

Answer 39

Blistering rash of the back of the mouth, caused by enteroviruses?

Question 40

Which viruses cause Hand, Foot and Mouth disease?

Answer 40

Enteroviruses

Question 41

What is slapped cheek disease also known as, and what virus causes it?

Answer 41

Erythema infectosium, caused by parvovirus B19

Question 42

Orf

Answer 42

A virus infection of the skin contracted from sheep and goats, presenting as firm, fleshy nodule on hands of farmers

Question 43

Which bacterium causes syphilis?

Answer 43

Treponema pallidum

Question 44

Which bacterium causes lyme disease?

Answer 44

Borrelia burgdorferi

Question 45

Which mosquito spreads Zika?

Answer 45

Aedes aegypti

Question 46

Which are the symptom onset and resolution of zika?

Answer 46

Onset: 3-12 days after exposure, Resolution: 2-7 days after onset

Question 47

What are complications of zika?

Answer 47

Guillain-Bare syndrome and microcephaly