Skin infections - Nanetti

Question 1

Bacterial skin infections

Answer 1

Impetigo
Callulitis
Erysipelas
Follicu;itis
Furnucles/boils
Carbucles
Erysipelas
Necrotizing

Question 2

What type of infection is folliculitis

Answer 2

staphylococcal

Question 3

What is folluculitis

Answer 3

inflam of hair follicles - Sty for eyelashes

Question 4

Aetiology

Answer 4

S.aureus infections - not infectious
or
yeast infec

Question 5

clincial presentation of folluculitis

Answer 5

small, ref, pus-filled pimples hair follicles (face, neck, tighs)

Itching and tenderness in area

Bactiera spread into the dermis

Question 6

Examples of deep folliculitis - infec spread to dermis

Answer 6

furuncles/boils

Carbucles

Question 7

Furuncles or boils (deep folliculitis)

Answer 7

Painful, larger, swollen bump with a central core
Infection spreads in the dermis attracting neutrophils  pus
Pus is sealed by an abscess  limiting infection

Question 8

Carbuncles (deeper folliculitis)

Answer 8

Cluster of connected furuncles or one furuncle not walled off
larger and deeper in dermis or hypodermis

s.aureus > can reach bloodstream > sepsis

Question 9

Erysipelas

Answer 9

in upper dermis

S. pyogenes enters the skin through breaks - NOT S.aureus.
It spreads quickly and it is more likely to reach lymph/blood vessels

Question 10

clinical pres of erysipelas

Answer 10

Well-defined, raised, and shiny red rash  Face, legs, arms.
Sharp borders, often with raised margins
Fever, chills and nausea

Question 11

Cellulitis

Answer 11

deep dermis - subcutaneous tissue

aetiology = Streptococcus pyogenes or S.aureus  most common
others involved (Streptococcus groups C and G)

Question 12

clinical pres of cellulitis

Answer 12

Commonly in one extremity of lower limbs, or face/trunk
Dark-red/purplish, swollen, warm, tense skin (with fluid)
The redness is less clearly defined than in erysipelas

Question 13

Necrotizing fasciitis (flesh-eating disease)

Answer 13

severe infection in subcutaneous tissues and below (deep fascia)

strep pyogenas, s.aureurs

Question 14

Clinical manifestations & pathogenesis
of necrotixing fasciitis

Answer 14

Strept A release proteolytic enzymes to penetrate into the subcutaneous tissues and below
Severe pain, swelling, and erythema. Rapid progression.
Skin changes, including blistering, necrosis. Fever & malaise
It may completely destroy the tissue, requiring amputation/surgery

Question 15

treatment for Superficial localised impetigo

Answer 15

Topical Hydrogen peroxide (H₂O₂) 1% cream
aspecific biocide  Generating free radicals  destroy bacterial cell components

Question 16

Superficial widespread impetigo

Answer 16

Topical antibiotics - fusidic acid or mupirocin (if fusidic acid resistance

Mechanism: Inhibition of the protein synthesis – bacteriostatic effect

Question 17

Bullous impetigo or patients with Non-bullous at risk of complications
Mild deeper infections (cellulitis/erysipelas)

Answer 17

Oral antibiotics
Flucloxacillin – as 1st line (500mg to 1g QDS – 5/7 days). Co‑amoxiclav if near the eyes
Clarithromycin or erythromycin (macrolides) as alternative first line - penicillin allergy

Question 18

Intravenous antibiotics

Answer 18

Intravenous Cefuroxime or Ceftriaxone (cephalosporins)
Or oral Co‑amoxiclav or oral clindamycin (lincosamine)

Question 19

Methicillin-resistant Staphylococcus aureus (MRSA)

Answer 19

Staph. aureus strains resistant to methicillin and other β-lactam antibiotics

Question 20

beta lactams high ____ MIC values to MRSA compared to MSSA

Answer 20

higher

Question 21

MRSA strains possess mecA gene, encoding for a transpeptidase that has _____ affinity for β-lactams

Answer 21

low

Question 22

Treatment for severe MRSA (or suspected):

Answer 22

Intravenous vancomycin or teicoplanin
glycopeptide inhibitors of the cell wall
or linezolid (protein synthesis inhibitor)

Question 23

low-risk HPV
e.g. HPV-6, 11

Answer 23

Ano-genital warts

Question 24

cancer types
(cervix, neck, anus)

Answer 24

High-risk
HPV-16, 18, 31, 45

Question 25

Cutaneous HPV

Answer 25

Cutaneous warts

Question 26

Warts/verrucae - Manifestations
- curtaneous

Answer 26

Benign solitary or multiple skin growths caused by cutaneous HPV
Grainy, cauliflower-like and slightly raised growths
On the hands, feet or on the sole of feet (verrucae/plantar warts)
Usually self-limiting, but can be embarrassing

Question 27

Wart spreading

Answer 27

They can spread though skin contact and sexually (genital warts).
HPV can be transmitted from contaminated surfaces (broken and/or wet).
HPC can survive for a long time on surfaces (swimming pool)

Question 28

Cutaneous wart formation

Answer 28

HPVs enter the broken skin

HPVs infect basal cells of the epidermis and establish persistent infection

Viruses encode viral oncogenes that stimulate cell division

Keratinocytes cannot mature or differentiate properly

Question 29

What are the treatment options for warts?

Answer 29

Topical salicylic acid - long treatment

AND/OR cryotherapy using liquid nitrogen (−196°C)
Thermal injury in the lesions to induce necrotic destruction of HPV-infected keratinocytes

Question 30

Herpes

Answer 30

prim. infec = develop lesions as cold sores - short lives

Question 31

How is Varicella zoster virus (VZV) caused?

Answer 31

agent of chickenpox (initial infection) and shingles (reactivation after latency)

Question 32

Treatement for herpes

Answer 32

Topical OTC acyclovir 5% cream for cold sores or genital herpes (4-6 times/day)
Reduce length of infection if administered within 24h from the initial symptoms (tingling on the lips)

Question 33

Oral treatments (acyclovir or prodrugs)

Answer 33

severe herpes infections and shingles, or infections in neonatal, elderly or immunocompromised patients (risk complications)
Antiviral therapy should start within 48-72 hours of the onset of shingles rash

Question 34

Fungal skin infections

Answer 34

Superficial/cutaneous dermatomycoses/tinea
Involve epidermidis stratus
Affecting trunk, feet, scalp, nails, groin areas

Subcutaneous mycoses
Involves dermis and subcutaneous tissue - Rare

Question 35

Dermatomycoses

Answer 35

Trunk, arms and legs – ringworm
Feet – athlete’s foot
Groin area - jock itch
Nails - onychomycosis