Skin and soft tissue infections

Question 1

what is diagnostic of Impetigo?

Answer 1

Golden crust, multiple vascular lesions on an erythematous base. It is a superficial skin infection, 2-5yo common, highly infectious

Question 2

what causes impetigo?

Answer 2

staph.aureus.

Question 3

Tx of impetigo

Answer 3

topical antibiotics and oral (e.g.flucloxacillin)

Question 4

outline Erysipelas

Answer 4

infection of the upper dermis, painful, red area, fever, lymphadenopathy, lymphangitis,, elevated borders, strep.pyrogenes, mostly effect the lower limbs and face.

Question 5

define Cellulitis

Answer 5

diffuse skin infection involving the deep dermis and subcutaneous fat.

Question 6

Cellulitis presentation and organism?

Answer 6

spreading erythematous area with no distinct borders. Strep.Pyogenes and staph.a (gram -ves effect diabetics and febrile neutropaenics)

Question 7

what are predispoding factors for Cellulitis?

Answer 7

DM, tinea pedis, lymphoedema

Question 8

Tx for Celliulitis and Erysipelas…

Answer 8

Fluclocacillin, iv benzylpenicillin, metronidazole.

Question 9

what is Folliculitis?

Answer 9

Pustular infection of a single hair follicle, px small red papules, head, back and buttocks, caused by staph a

Question 10

what is Furunculosis (boils)?

Answer 10

An inflammatory infection of a single hair follicle that extends deep into dermis and subcutaneous tissue, Usually affecting moist hairy areas of body. Caused by Staph.a

Question 11

RF for boils?

Answer 11

Obesity, Diabetes mellitus, Atopic dermatitis, Chronic kidney disease, Corticosteroid use

Question 12

what is a Carbuncle?

Answer 12

Large abscess involving multiple adjacent hair follicles, Occurs when infection extends to involve multiple furuncles, Often located back of neck, posterior trunk or thigh, multisepated, May drain spontaneously, otherwise need surgery of iv abx.

Question 13

define type 1 Necrotising Fasciitis

Answer 13

Mixed aerobic and anaerobic infections (ex gas gangrene)

Question 14

define type 2 Necrotising Fasciitis

Answer 14

Monomicrobial, usually associated with Streptococcus pyogenes

Question 15

Rapid onset NF

Answer 15

• Redness followed by oedema and severe pain
• Hypotension common
• Systemic features common
• Associated with multiorgan failure

Question 16

Pyomyositis

Answer 16

Purulent infection deep within striated muscle, often manifesting as an abscess
Infection is often secondary to seeding into damaged muscle, may involve multiple sites.
Constitutional symptoms common
Commonest cause Staphylococcus aureus, Surgery may be needed
tx - drainage and abx

Question 17

Septic bursitis

Answer 17

• Superficial bursae that are commonly affected include olecranon and patellar bursae
• Normally infection spreads from adjacent skin infection
• Most commonly caused by Staphylococcus aureus
• Constitutional symptoms common
• Need to differentiate from septic arthritis

Question 18

Infectious Tenosynovitis

Answer 18

• Most commonly affects flexor synovial sheats around tendons in hand
• Most common causes are Staphylococcus aureus and Streptococcus pyogenes
• Present as erythematous, fusiform swelling of finger
• Finger held in semiflexed position
• Such condition needs urgent review by a hand surgeon

Question 19

Toxin-mediated cutaneous infections

Answer 19

• Due to superantigens
• Toxic shock syndrome toxin 1 causes toxic shock syndrome (Staph and strep) manifesting itself as fever, rash, hypotension and organ failure
Tx - Remove offending agent (ex tampon), Intravenous fluids, Inotropes, Antibiotics, Intravenous immunoglobulins
• Exfoliative toxin A and B causes staphylococcal scalded skin syndrome manifesting as widespread bullae and skin exfoliation. Commonly affects children
• Panton-Valentine Leucocydin toxin from Staphylococcus aureus can cause recurrent boils and haemorrhagic pneumonias in children and young adults, It is a gamma haemolysin

Question 20

Venflon-associated infections: A form of nosocomial infection

Answer 20

• Risk factors include continuous intravenous infusion, >24 hours, cannula in situ >72 hours, cannula in lower extremity, patients with neurological and neurosurgical problems
• Common organisms include methicillin sensitive Staph aureus and MRSA
• Associated bacteraemia can seed to cause endocarditis and osteomyelitis
• Treatment is to remove cannula, antibiotics
• Prevention more important: do not leave unused cannulae, do not insert cannulae unless you are going to use them, change cannulae every 72 hours, monitor for developing infection, aseptic tech-nique when inserting cannulae

Question 21

Surgical site infections

Answer 21

• Clean wound infections:
- Infections in a surgical site that is sterile (example joint operations).
- Normally due to invasive organisms such as Staph aureus
• Contaminated wound infections:
- Infections at a surgical site that is either already contaminated at the start of surgery or contaminated during surgery (ex due to spillage of intracolonic contents following inadvertent perforation during abdominal surgery).
- Role of coliforms or anaerobic organisms
• MRSA important source of infection
• Importance of culturing all clean wound infections
• Treatment according to sensitivities