Lecture 13 Skin and Soft Tissue Infections Flashcards
What are clinical features of Impetigo
Golden crust lesion
What organisms commonly cause Impetigo
Staph aureus
Less commonly Strep Pyogenes
What age group os common affected by impetigo
2-5 years
What are predisposing factors of impetigo
o Skin abrasions o Minor trauma o Burns o Poor hygiene o Insect bites o Chickenpox o Eczema o Atopic dermatitis
How is impetigo treated
Topical antibiotics (small areas) Oral antibiotics (Flucloxacillin)
What is Erysipelas
Infection of the upper dermis
What are the clinical features of Erysipelas
Painful red area
Fever
Regional Lymphadenopathy and lymphangitis
Lower limbs
What organism is commonly associated with Erysipelas
Strep pyogenes
What pre-existing conditions increase the risk of Erysipelas
pre-existing lymphoedema, venous stasis, obesity, paraparesis, diabetes mellitus
What is cellulitis
Diffuse skin infection involving deep dermis and subcutaneous fat
What is the clinical presentation of cellulitis
Spreading erythematous with no distinct border
Fever
Regional lymphadenopathy and lymphangitis
What are the most likely causes of Cellulitis
Strep pyogenes
Staph aureus
Diabetes
Febrile neutropeanics
What are predisposing factors of Cellulitis
DM
Tinea pedis
Lymphoedema
How is Erysipelas and Cellulitis treated
Combination of anti-staphylococcal and anti-streptococcal antibiotics
In extensive disease, admission for intravenous antibiotics and rest
What is folliculitis
o Circumscribed, pustular infection of a hair follicle
o Up to 5mm in diameter
What are the clinical features of folliculitis
o Present as small red papules
o Central area of purulence that may rupture and drain
o Typically found on head, back, buttocks and extremities
What is the common causative agent of folliculitis
Staph aureus
What is Furunculosis
Boils
Single hair follicle-associated inflammatory nodule
What areas to Furunculosis occur
Usually affected moist, hairy, friction-prone areas of body (face, axilla, neck, buttocks)
What is a carbuncle
Occurs when infection extends to involve multiple furuncles
Where are the common locations of carbuncles
neck, posterior trunk, or thigh
How are hair-associated infections treated
Folliculitis- no treatment or topical antibiotics
Furunculosis- no treatment or topical antibiotics
Carbuncles- often require hospital admission, surgery and IV antibiotics
What is type 1 Necrotising fasciitis
Mixed aerobic and anaerobic infection (diabetic foot infection, Fornier’s gangrene)
Typical organisms that cause type 1 necrotising fasciitis
o Streptococci o Staphylococci o Enterococci o Gram negative bacilli o Clostridium
What is type 2 necrotising fasciitis
Mono-microbial
Normally associated with strep pyogenes
What are the clinical features of necrotising fasciitis
Erythema extensive oedema haemorrhagic bullae Skin necrosis and crepitus Fever Hypotension tachycardia Delirium Multi-organ failure
How is necrotising fasciitis treated
Antibiotics should be broad spectrum
o Flucloxacillin
o Gentamicin
o Clindamycin
What is pyomyositis
Purulent infection deep within striated muscle, often manifesting as an abscess
Secondary to damaged muscle
Common sites of Pyomyositis
o Thigh o Calf o Arms o Gluteal region o Chest wall
What are the clinical features of pyomyositis
fever, pain and woody induration of affected muscle
If untreated can lead to septic shock and death
What is the common causative organism of pyomyositis
Staph aureus
How is pyomyositis diagnosed
CT/MRI
How is Pyomyositis treated
Drainage with antibiotic cover depending on gram stain and culture
What is septic bursitis
Infection of bursae -small sac-like cavities that contain fluid and are lined by synovial membrane
Located subcutaneously between bony prominences or tendons
Predisposing factors of septic bursitis
o Alcoholism o RA o DM o IV drug abuse o Immunosuppression o Renal insufficiency
What are clinical features of septic bursitis
fever and pain in movement
How is septic bursitis diagnosed
Aspiration of fluid
Staph aureus
What is infectious tenosynovitis
Infection of the synovial sheaths that surround tendons
What are the common causes of infectious tenosynovitis
Staph aureus and streptococci
Penetrating trauma
What are the clinical features of infectious tenosynovitis
- Tenderness over the length of the tendon sheath and pain with extension of finger are classical
- Present with erythematous fusiform swelling of finger
How is infectious tenosynovitis treated
Empiric antibiotics, hand surgeon to review ASAP
What are the causative agents of Toxin-mediated syndromes
Staph aureus- TSST1, ETA and ETB
Strep pyogenes- TSST1
What are the diagnostic criteria for staphylococcal TSS
• Fever • Hypotension • Diffuse macular rash • Three of the following organs involved o Liver o Blood o Renal o GI o CNS o Muscular
How is TSS treated
- Remove offending agent (ex-tampon)
- IV fluids
- Inotropes
- Antibiotics
- IV immunoglobulins
What is Staphylococcal scalded skin syndrome
• Infection due to a particular strain of Staph aureus producing the exfoliate toxin A or B
What are the clinical features of staphylococcal scalded skin syndrome
Widespread bullae and skin exfoliation
How is staphylococcal scalded skin syndrome treated
IV fluids and antimicrobials
Causes of surgical site infections
- Staph aureus
- Coagulase negative Staphylococci
- Enterococcus
- E. coli
- P. aeruginosa
- Enterobacter
- Streptococci
- Fungi
- Anaerobes
Risk factors for surgical site infections
- DM
- Smoking
- Obesity
- Malnutrition
- Concurrent steroid use
- Colonisation with Staph aureus
- Procedural factors
How are surgical site infections diagnosed
- Importance of sending pus/infected tissue for cultures especially with clean wound infections
- Avoid superficial swabs- aim for deep structures
- Consider an unlikely pathogen as a cause if obtained from a sterile site (ex bone infection)
- Antibiotics to target likely organisms
