13. Skin and soft tissue infections

Question 1

Who gets skin and soft tissue infections?

Answer 1

Diabetes leading to neuropathy and vasculopathy
Immunosuppresion
Renal failure
Milroy’s disease
Predisposing ski diseases (atopic dermatitis)

Question 2

What else is important is good to consider

Answer 2

Site of infection and potential complications
Drug resistant strains? (MRSA)
Drug interactions
Drug allergies

Question 3

What organism is very common for skin and soft tissue infections?

Answer 3

Staph Aureaus

Question 4

What is impetigo?

Answer 4

Superfifical skin infection, highly infectious and common in children 2-5 years old.

Question 5

How does impetigo present?

Answer 5

Ususally occurs on expose parts of the boies such as face, extremities and scalp.
Multiple vesicluar lesions n an erythematous base
Golden crust is highly suggestive of this diagnosis
Most commonly due to staph aureus

Question 6

What are predisposing factors to impetigo?

Answer 6

Skin abrasions
Minor trauma
Burns
Poor hygiene
Insect bites
Chickenpox
Eczema
Atopic dermatitis

Question 7

What is the treatment of impetigo?

Answer 7

small areas of infection- topical antibiotics

Large areas of infections- oral antibiotics e.g. flucloxacillin

Question 8

What is erysipelas?

Answer 8

Infection of the upper dermis. 70-80% is found on the lower limbs. there is a high recurrence rate

Question 9

How does erysipelas present?

Answer 9

Red, bubbly stretched skin,
associated fever
regional lymphadenopathy and lmyphangitis
elevated borders, typically cuased by strep pyogenes

Question 10

What are predisposing factors to erysipelas?

Answer 10

Lymphoedema
venous stasis
obesity
paraparesis
diabetes

Question 11

What is cellulitis

Answer 11

Diffuse skin infection involving deep dermis and subcutaneous fat

Question 12

How does cellulitis present

Answer 12

spreading erythematous area with no distinct borders
Fever is common
Regional lymphadenopathy and lymphangitis
Possible of bactearemia
Staph aureus and strep pyogenes most common organisms

Question 13

What are predisposing factors to cellulitis?

Answer 13

Diabetes
Tinea pedis (athletes foot)
Lymphoedema

Question 14

How do you treat erysipelas and cellulitis?

Answer 14

Combination of anti staph and anti strep antibiotics

In extensive disease admit and treat with IV antibiotics and rest

Question 15

What are the three follicle associated infections?

Answer 15

Folliculitis- single follicle involvement
Furuculosis- red, tender nodule surrounding a follicle with one draining point)
Carbuncles- deep abscess of several follicles with several draining points

Question 16

What is folliculitus?

Answer 16

Circumscribed pustular infection of a hair follicle

Question 17

How does folliculitis present?

Answer 17

Presents as small red papules
Central area of purulence that may rupture and drain
Most common organsism is staph aureus, not serious

Question 18

What is furinculosis?

Answer 18

Furuncles commonly referred to as boils

Single hair nodule associate inflammatory nodules

Question 19

How does furinculosis present?

Answer 19

Usually swelling ad redness on areas in the face,axilla, neck, buttocks. Staph aureus is the most common organism but systemic symptoms are uncommon. Mo treatment often required

Question 20

What are the risk factors for furunculosis?

Answer 20

Obesity 
Diabetes
Atopic dermatitis
Chronic kidney disease
Corticosteroid use

Question 21

What are carbuncle’s?

Answer 21

Infections that involve multiple furuncles.

Question 22

How do carbuncle’s present?

Answer 22

Often in back of neck, posterior trunk or thigh
Multiseptated abscesses
Purulent material may be expressed from multiple sites
Constitutional symptoms may be common

Question 23

How do you treat carbuncle’s?

Answer 23

Often require admission to hospital, surgery and IV antibiotics

Question 24

What is necrotising fasciitis?

Answer 24

An emergency of infectious disease, skin eating bacteria affecting any site in the body

Question 25

What organsisms cause necrotising fasciitis?

Answer 25

``` Streptococci Staphylococci Enterococci Gram negative bacilli Clostridium ```

Question 26

What predisposes people to necrotitsing fasciitis?

Answer 26

``` Diabetes mellitus Surgery Trauma Peripheral vascular disease Skin popping- injecting IV drugs but missing the vein ```

Question 27

What are the different types of necrotising fasciitis?

Answer 27

Type 1- mixed aerobic and anaerobic infection Type II- monomicrobial, typically associated with strep pyogenes. Fast onset, sepsis comes on very quick.

Question 28

How does necrotising fasciitis present?

Answer 28

Rapid onset, unremitting pain, oedema, erythema Heamorrhagic bullae, skin necorsis, crepitus Systemic features e.g. fever, hypotension, tachycardia, delirium and multiorgam failure. Parastesthia at site of infection points towards

Question 29

How do you treat Necrotising fasciitis?

Answer 29

Surgical review is mandatory, imaging may help but can delay treatment Broad spectrum antibiotics- flucloxacillin, Gentamicin, clindamycin Overall mortality high

Question 30

What is pyomyosisits?

Answer 30

Purulent infection deep within skeletal muscle often manifesting as an abscess

Question 31

How does it present?

Answer 31

fever, pain or woody muscle (pushing on muscle feels like pushing on wood) If untreated leads to septic shock and death infection often to damage to the msucele. Common sites include: Thigh Calf Arms Glutes Chest wall Psoas muscle Commonest cause is staph aureus

Question 32

How do you treat pyomyosistis?

Answer 32

Investigate using CT/MRI Drainage with antibiotics cover depending on stain and culture results

Question 33

How do you treat pyomyosistis?

Answer 33

Investigate using CT/MRI Drainage with antibiotics cover depending on stain and culture results

Question 34

What is septic bursistis?

Answer 34

Infection of te small sac like cavities that are lined by synovial membrane.

Question 35

How doe septic bursitis present?`

Answer 35

Infection is often from adjacent skin infection. Peribursal cellulitis, swelling and warmth are common Fever and pain on movement are also seen Commonest cause is staph aureus

Question 36

What are the predisposing factors to bursitis?

Answer 36

``` RA Alcoholism Diabetes IV drug abuse Immunosupression Renal insufficiency ```

Question 37

What is the treatment of septic bursitis?

Answer 37

Diagnosis is based on aspiration of the fluid | Treat with antibiotics

Question 38

What is infectious tenosynovitis

Answer 38

Infection of the synovial sheaths that surround tendons

Question 39

How does infected tenosynovitis present

Answer 39

Flexor muscle associated especially in the hands Penetrating trauma the most inciting event Muscle will be in a semiflexed position Tenderness over length of sheath and pain on extension Most common cause is staph aureus

Question 40

How do you treat infected tenosynovitis?

Answer 40

Empircal antibiotcs and get the surgeons involved

Question 41

What are toxin mediated syndromes?

Answer 41

Often due to sueprantigens, group of pyrogenic atigens Actvivate vast amount sof T cells causing endothelial leakage, haemodynamix hock, multiorgan failure adn eath Mostly staph aureus and strep. pyogenes

Question 42

What is toxic shock syndrome?

Answer 42

Can be due to small skin infections are the use of high absorbency tampons

Question 43

How does toxic shock syndrome present?

Answer 43

Fever, hypotension, diffuse macular rash 3/6 involved- Liver, blood, renal GI, CNS, MSK TSST1 is produced and induces antibody toxin

Question 44

How do you treat toxic shock syndrome?

Answer 44

``` Remove offending agent Intravenous fluids Inotropes Antibiotics Intravenous immunoglobulins ```

Question 45

What is staphylococcal scalded skin syndrome?

Answer 45

Infection due to a particular strain of staph aureus producing exfoliative toxin A or B

Question 46

How does staphylococcal scalded syndrome present?

Answer 46

Characterised by widespread bullae and skin exfoliation Usually occurs in children but rarely in adults Treat with IV fluids and antibiotics

Question 47

What are intravenous catheter associated infections?

Answer 47

What they say on the tin

Question 48

How do intravenous catheter associated infections present?

Answer 48

local SST inflammation leading to cellulitis, common to have bacteraemia Most common agents are MSSA and MRSA Commonly form a biofilm which spills into the bloodstream Can seed into other places e.g. endocarditis, osteomyetits

Question 49

Hwo do you treat intravenous catheter associated infections?

Answer 49

Remove cannula Express any pus from the thrombophlebitis Antibiotics for 14 days Echcardiogram

Question 50

How do you prevent IV catheter associated infections

Answer 50

Do not leave unused cannulae Do not insert cannulae unless yo are using them Change cannulae every 72 hours Monitor for thrombophlebitis Use aseptic technique when inserting cannulae

Question 51

What are the classifications of surgical wounds?

Answer 51

Class I- clean wound Class II- clean-contaminated wound- tracts entered but no unusual contamination Class III- contaminated wound Class IV- infected wound

Question 52

What are risk factors for surgical wounds becoming infected?

Answer 52

``` Diabetes, smoking obesity malnutrition concurrent steroid use colonisation with staph aureus Shaving night before break in sterile techniquw perioperative hypoxia ```

Question 53

How do you diagnose surgical wound infections?

Answer 53

Avoid superfificla swabs, aim for dee structures and send cultures away Consider an unlikely pathogen if obtained rom sterile site e.g. bone Antibiotics to target organsim