Skin and Soft Tissue Infections Flashcards
What is Impetigo
Superficial Skin infection
How does impetigo present
Multiple vesicular lesions on an erythematous base with a golden crust
State the possible causes of impetigo
Staph aureus or strep pyogenes
In which area of the population is impetigo present
2-5 years
Where does impetigo tend to occur
Face, extremities and scalp
List the predisposing factors of impetigo
Skin abrasions, minor trauma, burns, poor hygiene, insect bites etc
State the treatment of impetigo
Small areas treated with topical antibiotics alone but large areas may need flucloxacillin
What us erysipelas
Infection of the upper dermis
State the symptoms of erysipelas
Painful red area, associated fever, regional lymphadenopathy and lympgangitis, distinct elevated borders
What organism tends to cause erysipelas
Strep pyogenes
Where does erysipelas tend to occur
The face and the lower limbs. In areas of pre-existing oedema
State the recurrence rate of erysipelas
30% within 3 years
What is cellulitis
Diffuse skin infection involving the deep dermis and subcutaneous fat.
How does cellulitis present
It presents as a spreading erythematous area with no distinct borders, fever, regional lymphadenopathy
State the most likely organisms for causing cellulitis
Strep pyogenes and staph aureus
List the predisposing factors for cellulitis
Diabetes, tinea pedis and lymphoedema
State the treatmentof erysipelas and cellulitis
Combination of anti-staph and anti-strep antibiotics
What is folliculitis
Circumscribed, pustular infection of a hair follicle
How does folliculitis present
Small red papules with central area of purulence that may rupture and drain
Where is folliculitis often found
Head, back, buttocks and extremities
State the most common causative organism of folliculitis
Staph Aureus
What is furunculosis
Single hair follicle associated inflammatory nodules which extend into the dermis and subcutaneous tissue
Which area is mostly affected by furunculosis
Moist, hairy, friction prone areas of skin
State the most common causative organism of furunculosis
Staph aureus
List the risk factors of furunculosis
Obesity, diabetes, atopic dermatitis, chronic kidney disease, corticosteroid use
What is a carbuncle
Infection extending to involve multiple furuncles
Where are carbuncles often located
Back of the neck, posterior trunk or thigh
State the treatment of carbuncles
Admission to hospital, surgery and intravenous antibiotics
State the predisposing conditions for necrotising fascitis
Diabetes, surgery, trauma, peripheral vascular disease, skin popping
What is a type 1 necrotising fasciitis infection
Mixed aerobic and anaerobic infection
State the typical organisms that can cause nectrotising fasciitis
Streptococci, staphylococci, enterococci, gram negative bacteria, clostridium
What is type 2 necrotising fasciitis
Monomicrobial usually with strep pyogenes
State the clinical features of necrotising fasciitis
Rapid onset, sequential development of erythema, extensive oedema and severe pain. Haemorrhagic bullae, skin necrosis and crepitus may develop
State the systemic features of necrotising fasciitis
Fever, hypotension, tachycardia, delirium and multiorgan failure
What feature is highly suggestive of necrotising fasciitis
Anaesthesia at the site of infection
State the treatment of necrotising fasciitis
Flucloxacillin, gentamicin, clindamycin
State the mortality rates of necrotising fasciitis
17-40%
What is pyomyositis
Purulent infection deep within striated muscle, often manifesting as an abscess
State the common sites of pyomyositis
Thigh, calf, arms, gluteal region, chest wall and psoas muscle
State the presentation of pyomyositis
Fever, pain and woody induration of affected muscle
List the predisposing factors of pyomyositis
Diabetes, HIV, IV drug use, malignancy, liver cirrhosis
State the organism most likely to cause pyomyositis
Staph aureus
State how pyomyositis should be investigated
CT/MRI
How is pyomyositis treated
Drainage with antibiotic cover
What is septic bursitis
Infection of bursae within joints
State the predisposing factors for septic bursitis
Rheumatoid arthritis, alcoholism, diabetes mellitus, IV drug abuse, immunosuppression, renal insufficiency
State the clinical features of septic bursitis
Cellulitis, swelling, warmth, fever, pain on movement
How is septic bursitis diagnosed
Aspiration of fluid
State the most common causative organism of septic bursitis
Staph aureus
What is infectious tenosynovitis
Infection of the synovial sheats that surround tendons
Which tendons are most commonly involved in infectious tenosynovitis
Flexor muscle associated tendons of the hand
What is commonly the inciting event in infectious tenosynovitis
Penetrating trauma
State the most common causative bacteria of tenosynovitis
Staph aureus and streptococci
What is the symptoms of infectious tenosynovitis
Erythematous fusiform swelling of finger, tenderness over the length of the tendon sheath and pain with extension of the finger classical
State the treatment of infectious tenosynovitis
Empiric antibiotics and hand surgeon review
How do toxic mediated infections cause such a response
Bypass normal immune system and attach directly to T cell receptors activating up to 20% of the total pool of T cells. This results in a massive burst of cytokines leading to endothelial leakage etc
What organisms tend to cause Toxin Mediated Syndrome
Staphylococcus aureus and Streptococcus pyogenes
State the toxins released by Staph aureus
TSST1, ETA and ETB
State the toxins released by strep pyogenes
TSST1
State the diagnostic criteria for staphylococcal TSS
Fever, hypotension, diffuse macular rash, involvement of three of liver, blood, renal GI, CNS, muscular, isolation of Staph Aureus from mucosal sites, production of TSST1 by isolate, development of antibody to toxin during convalescence
Where does streptococcal TSS usually come from
Deep seated infections such as erysipelas or necrotising fasciitis
State the treatment of TSS
Remove offending agent, IV fluids, inotropes, antibiotics, IV immunoglobulins
What is Panton-Valentine Leucocidin Toxin
Gamma Haemolysin
What can Panton-Valentine Leucocidin Toxin cause
SSTI and haemorrhagic pneumonia
Patients with Panton-Valentine Leucocidin Toxin present with
Recurrent boils which are difficult to treat
How is Panton-Valentine Leucocidin Toxin treated
Antibiotics that reduce toxin production
How do Intravenous Catheter associated infections usually presenht
SST inflammation, progressing to cellulitis and even tissue necrosis
State the risk factors of IV catheter associated infections
Continuous infusion>24 hours, Cannula in situ >72 hours, cannula in lower limb
State the most common organism causing IV catheter infections
Staph aureus
State the treatment if IV catheter associated infections
Remove cannula, express pus, antibiotics for 14 days and Echo
Class 1 surgical site infection
Clean wound
Class 2 surgical site infection
Clean-contaminated wound
Class 3 surgical site infection
Contaminated wound
Class 4 surgical site infection
Infected wound
List the possible causes of surgical site infections
Staph aureus, coagulase negative staph, enterococcus, E.coli, psuedomonas aeruginosa, enterobacter, streptococci, fungi, anaerobes
How are surgical site infections diagnosed
Cultures