Skin and soft tissue infections

Question 1

What are the three skin layers acting as a defensive barrier against pathogens?

Answer 1

Epidermis, dermis, hypodermis

Question 2

How does the epidermis defend against pathogens?

Answer 2

Hard layer of dead cells, dry surface, acidic pH, constant sloughing, antimicrobial substances

Question 3

Name antimicrobial substances secreted by the skin

Answer 3

Fatty acids, sebum, defensins

Question 4

What happens if the skin barrier is broken?

Answer 4

Pathogens can enter and cause infections

Question 5

What types of pathogens cause SSTIs?

Answer 5

Bacteria, viruses, fungi

Question 6

Name two bacteria that are part of the normal skin microbiota

Answer 6

Staphylococcus epidermidis (coagulase-negative), Staphylococcus aureus (coagulase-positive).

Question 7

Which skin microbiota bacterium is associated with acne?

Answer 7

Propionibacterium acnes

Question 8

What project highlighted belly button microbiota diversity?

Answer 8

Belly button biodiversity project

Question 9

Name three common routes of infection for the skin

Answer 9

Wounds (cuts, scratches, burns), animal/insect bites

Question 10

What should be assessed when taking a history for a skin infection

Answer 10

Onset, evolution, duration, location, contacts, PMH, prior treatments, trauma, systemic features, comorbidities, exposure risks

Question 11

Why is knowledge of previous antibiotic use important?

Answer 11

It may influence resistance patterns

Question 12

Name two pathogens that can either friend or foe to the skin

Answer 12

S. aureus, C. acnes.

Question 13

What infection can diabetes mellitus predispose a patient to?

Answer 13

S. aureus wound infection.

Question 14

What is wound dehiscence?

Answer 14

Premature bursting of a wound along a surgical suture

Question 15

Why are catheters a risk for infections?

Answer 15

Bacteria form biofilms on them

Question 16

Which bacteria are commonly involved in catheter-related infections?

Answer 16

Coagulase-negative staphylococci and Pseudomonas aeruginosa

Question 17

Are blood/wound cultures always necessary in skin infections?

Answer 17

No, they are not always needed; empiric therapy is ofeten started

Question 18

What two bacteria commonly cause impetigo?

Answer 18

Staphylococcus aureus and Streptococcus pyogenes

Question 19

What toxin-related disease can S. aureus cause in children?

Answer 19

Staphylococcal Scalded Skin Syndrome

Question 20

What is the Nikolsky sign?

Answer 20

Gentle stroking of the skin causes separation of the epidermis

Question 21

What skin infection typically affects the upper dermis and face?

Answer 21

Erysipelas

Question 22

What are the key bacteria causing cellulitis?

Answer 22

Streptococcus pyogenes (2/3), Staphylococcus aureus (1/3).

Question 23

What deeper infection involves connective tissues and can become life-threatening

Answer 23

Cellulitis.

Question 24

What is necrotizing fasciitis?

Answer 24

A rapidly progressing infection of the fascia causing tissue death.

Question 25

Which fungi cause ringworm (tinea)?

Answer 25

Trichophyton, Microsporum, Epidermophyton.

Question 26

What is Tinea corporis?

Answer 26

Ringworm of the body.

Question 27

What is Tinea pedis?

Answer 27

Athlete’s foot.

Question 28

What is Tinea cruris?

Answer 28

Ringworm of the groin.

Question 29

Name two yeasts causing skin infections.

Answer 29

Candida albicans, Malassezia furfur.

Question 30

What virus causes warts?

Answer 30

Human papilloma virus (HPV).

Question 31

What serious disease is linked to HPV infection?

Answer 31

Cervical cancer.

Question 32

What vaccines are offered to prevent HPV infections?

Answer 32

Vaccines to 12–13-year-olds (male and female).

Question 33

Which HSV type most often causes cold sores in the UK?

Answer 33

HSV-1.

Question 34

Which HSV type is more likely to cause recurrent genital herpes?

Answer 34

HSV-2.

Question 35

How is HSV transmitted?

Answer 35

HSV1 through saliva and bodily secretions; HSV2 through sexual contact.`

Question 36

What virus causes chickenpox and shingles?

Answer 36

Varicella zoster virus (VZV).

Question 37

Where does VZV remain dormant after chickenpox?

Answer 37

In the dorsal root ganglia (nerve cells).

Question 38

What characterises shingles?

Answer 38

Grouped vesicular lesions along a dermatome

Question 39

What causes hand, foot and mouth disease?

Answer 39

Coxsackievirus A16 and other Enteroviruses.

Question 40

How is hand, foot, and mouth disease transmitted?

Answer 40

Saliva, stool, fluid from blisters, contaminated surfaces.

Question 41

Name two parasites that infest the skin.

Answer 41

Sarcoptes scabiei (scabies), Pediculus humanus (lice).

Question 42

What causes scabies?

Answer 42

Mite Sarcoptes scabiei burrowing into the skin.

Question 43

How is scabies transmitted?

Answer 43

Person-to-person skin contact.

Question 44

How long can symptoms of scabies take to appear?

Answer 44

Up to 8 weeks.

Question 45

What is the main management principle for animal bites?

Answer 45

"The solution to pollution is dilution" — irrigate the wound thoroughly.

Question 46

Which bacteria is commonly associated with cat bite infections?

Answer 46

Pasteurella multocida.

Question 47

What distinguishes dog bite wounds from cat bite wounds?

Answer 47

Dog bites are larger, tearing, crushing wounds with a high contamination risk.

Question 48

Why are human bites particularly concerning?

Answer 48

Highly polymicrobial and deeper infections are common.

Question 49

Name three microbes associated with human bite infections.

Answer 49

Eikenella corrodens, S. pyogenes, viral pathogens (e.g., HIV, Hepatitis B/C).

Question 50

What are the antibiotic durations for different bite-associated infections?

Answer 50

Cellulitis: 7–10 days Tenosynovitis: 21 days Septic arthritis: 28 days Osteomyelitis: 42 days