Skin and Soft Tissue Infection Flashcards
Which bacteria make up the normal skin flora?
Gram positives such as diptheroids, corynebacteria, anaerobes, staphylococci and streptococci
On what areas of the skin is s.aureus most commonly found?
Nose and moist areas of the skin
In which areas of the body is s.pyogenes commonly found as a commensal?
Respiratory or vaginal tract
What are general predisposing factors to cellulitis?
Pregnancy
Caucasian
Venous insufficiency
Lymphoedema
What are local factors which can predispose to cellulitis?
Trauma, animal/insect bites, tattoos, ulcers, eczema, athlete’s foot, burns and surgery
What factors are important to assess when classifying skin and soft tissue infection?
Severity
Anatomical site
Comorbidity
Hospital acquired infection
What classes of skin and soft tissue infection are admitted to hospital?
Class two (if no outpatient parenteral antimicrobial therapy facilities are available) Classes three and four
Which classes of skin and soft tissue infection require management with IV antibiotics?
Classes 2, 3 and 4
In addition to IV antibiotics, which classes of skin and soft tissue infection require surgical management?
Class 4
Describe class one skin and soft tissue infection
No signs of systemic toxicity
No comorbidities
Treated as outpatient with oral antibiotics
Describe class two skin and soft tissue infection
Possible signs of systemic illness
Possible comorbidities of: obesity, venous insufficiency and peripheral vascular disease
Treated as inpatient with IV antibiotics unless outpatient parenetaral antimicrobial therapy facilities are available.
Describe class three skin and soft tissue infection
Signs of significant systemic illness
Unstable
Treated as inpatient with IV antibiotics
Describe class four skin and soft tissue infection
Signs of sepsis or necrotising fasciitis
Unstable
Treated as inpatient with IV antibiotics and surgery
What specific groups of patients should always be admitted to hospital for treatment of skin and soft tissue infections?
Immuocompromised patients
Very young children (<1 year)
Cellulitis at which sites should always be admitted to hospital for treatment?
Facial cellulitis
Suspected orbital or periorbital cellulitis (referred to ophthalmology)
Typical cellulitis is caused by s.pyogenes. What antibiotics are used to treat this?
Amplicillin or flucloxacillin
Typical pus forming cellulitis is caused by which organisms?
S.aureus
MRSA
Typical pus forming cellulitis is caused by s.aureus (possibly MRSA). How is this treated?
Flucloxacillin
Vancomycin
How should skin and soft tissue infection be treated when there is a penicillin allergy?
Doxycycline
Clindamicin
Vancomycin
What organism commonly causes skin/soft tissue infection as a result of a dog or cat bite?
Pasturella multocida
Pasturella multocida commonly causes skin/soft tissue infection as a result of a dog or cat bite. How is this treated?
Co-amoxiclav
Doxycycline + metronidazole
What organism commonly causes skin/soft tissue infection as a result of a freshwater exposure?
Aeromonas hydrophila
Aeromonas hydrophila commonly causes skin/soft tissue infection as a result of a freshwater exposure. How is this treated?
Ciprofloxacin
What organism commonly causes skin/soft tissue infection as a result of a salt water exposure?
Vibrio vulnificus
Vibrio vulnificus commonly causes skin/soft tissue infection as a result of a salt water exposure. How is this treated?
Doxycycline
What organism commonly causes necrotising fasciitis?
Clostridium perfringes
S.pyogenes
Which antibiotics are commonly used to treat necrotising fasciitis?
Penicillin Flucloxacillin Clindamycin Gentamicin Metronidazole
What organism commonly causes skin/soft tissue infection in butchers and fish handlers?
Erysipelothrix
Erysipelothrix commonly causes skin/soft tissue infection in butchers and fish handlers. How is this treated?
Ciprofloxacin
List differential diagnoses of skin and soft tissue infection?
Stasis dermatitis Acute arthritis Pyoderma gangrenosum Hypersensitivity or drug reaction DVT Necrotising fasciitis
Explain how stasis dermatitis can be distinguished from skin and soft tissue infection?
Absence of pain and fever
Circumferential
Bilateral
Explain how acute arthritis can be distinguished from skin and soft tissue infection?
Joint involvement
Pain on movement
Explain how pyoderma gangrenosum can be distinguished from skin and soft tissue infection?
Ulcerations on legs
History of inflammatory bowel disease
Explain how hypersensitivity/drug reactions can be distinguished from skin and soft tissue infection?
Exposure to allergens/drug
Pruritis
Absence of fever and pain
Explain how DVT can be distinguished from skin and soft tissue infection?
Absence of skin changes or fever
Explain how necrotising fasciitis can be distinguished from skin and soft tissue infection?
Severe pain out of proportion Swelling Fever Rapid progression Systemic toxicity
What is necrotising fasciitis?
Rapidly spreading infection of the subcutaneous fascia
Necrotising fasciitis is toxin mediated. T/F?
True
Describe the clinical manifestation of necrotising fasciitis?
Remarkably rapid progression
Most common on extremities e.g. legs
Initially erythema and swelling without sharp mergins
Exquisite pain and tenderness
Lymphatic involvement is rare
Colour changes from red-purple to blue-grey
Skin breakdown and bullae with development of anaesthesia
Probing of lesion reveals easy passage through tissues
How is necrotising fasciitis treated?
Surgical debridement
IV antibiotics: penicillin, flucloxacillin, clindamycin, gentamicin and metronidazole
Which organisms cause erysipelas?
Group A strep
Rarely group B, S and G s.aureus
Describe the appearance of erysipelas?
Skin/soft tissue infection
Raised lesion with a clear line of demarcation
Classical butterfly involvement
What age groups are particularly susceptible to erysipelas?
Infants
Elderly
What is impetigo?
Staphylococcal infection of the epidermis which forms a honey coloured crust and is often peri oral
What groups of people are most commonly affected by impetigo?
Children
Sports persons
How is impetigo managed?
Gently removing crust
Flucloxacillin
Management of secondary infection
S.aureus strains produce an exfoliative exotoxin which causes widespread bullae and exfoliation. What is this known as in the neonate?
Ritter’s disease or Pemphigus neonatorum
S.aureus strains produce an exfoliative exotoxin which causes widespread bullae and exfoliation. What are the symptoms of this?
Fever
Tenderness
Scarlatiniform rash
S.aureus can produce the toxin PVL. What is the action of this toxin?
Destroys white blood cells
What conditions is PVL producing s.aureus associated with?
Necrotising pyogenic skin infections
Septic arthritis
Fulminant pneumonia
Community isolates of s.aureus are more likely to carry to PVL toxin than hospital isolates. T/F?
True
When should PVL producing s.aureus be suspected?
Patients with recurrent or multiple boils especially those in close contact situations
How is PVL producing s.aureus skin/soft tissue infection managed?
Drainage
Treatment according to sensitivity patterns
Nose, throat, axilla, perineum and skin lesions screened for carriage
What is scarlet fever caused by?
Infection with a streptococcal strain which has pyrogenic exotoxins or erythrogenic toxins
Scarlet fever usually occurs post pharyngitis. T/F?
True
Scarlet fever can complicate wound infections and post partum infections. T/F?
True
Describe the appearance of scarlet fever?
Diffuse red blush which appears on the second day of infection with a point of deeper rich blanche on pressure
Starts on upper chest the spreads to trunk, neck and extremities
Occlusion of sweat glands gives skin a sandpapery touch
Which sites are usually spared in scarlet fever?
Palms
Soles
Face
Describe the appearance of the tongue in scarlet fever?
White strawberry tongue then ed strawberry tongue
When is prophylaxis following a bite recommended?
Deep bites
Hand bites
Splenectomised or immunocompromised patients
Crush injuries
How are infected bones treated?
Aggressive debridement
Abscess drainagae
Antibiotics
Cat bites are more likely to become infected than dog bites. T/F?
True
Which pathogen is most commonly isolated from bites?
Pasturella
How is pasturella infection as a result of a bite treated?
Penicllins Cephalosporins Tetrayclines Quinolones Macrolides
Which organism can commonly infect puncture wounds from crabs?
Erysipelothrix rhusiopathiae
Aeromonas infection from fresh water exposure results in skin/soft tissue infection with the following features…?
Rapidly developing infection associated with fever and sepsis
Edwardsiella trade infection from fresh water exposure results in skin/soft tissue infection with the following features…?
Cellulitis
Occasionally fulminant infection with bacteraemia
Describe the clinical syndrome which results from erysipelothrix rhusiopathiae infection of puncture wounds from crabs?
Indolent localised cutaneous eruption
Erypsipeloid
Describe the clinical syndrome which results from vibrio velnificus skin/soft tissue infection from salt or brackish waters?
Rapidly progressive necrotising infection, bullies cellulitis, sepsis
Describe the clinical syndrome which results from mycobacterium marine skin/soft tissue infection from fresh or salt water exposure?
Indolent infection
Papules to ulcers
Ascending lesions may resemble sporotrichosis
Define ‘burns’
Damage to the skin caused bay heat/chemicals/radiation which results in protein denaturing
Describe the classification of a superficial (1st degree) burn
Dry, red, glances on pressure, painful, heals in a week
Describe the classification of a partial thickness (2nd degree) burn
Superficial or deep Blisters Pain Heals in less than 3 weeks Treated with antibiotics, surgery and grafting
Describe the classification of a full thickness (3rd degree) burn
Painless
Non-blanching
Treated with surgery
What are the possible complications of burns?
Infection
Hypothermia
Acid-base abnormalities
Dehydration
How are infected burns managed?
Cleaning Dressings Topical antimicrobials (silver salfadiazine, bismuth compounds, chlorhexidine) Topical antibiotics Systemic antibiotics
What are the major features of cutaneous anthrax?
Extensive oedema
Painless
Non-tender
What are the minor features of cutaneous anthrax?
Black eschar Progresses over 2-6 days through papular, vesicular and ulcerated stages before eschar appears Affects hands, forearms, face and neck Discharge of serous fluid Local erythema and induration Local lymphadenopathy Systemic malaise - headache, chills, sort throat Afebrile
What are the risk factors for cutaneous anthrax?
Working with animals or animal hides
Making/owning or playing animal hide drums
Drug use (heroin)
Travel
Working in postal sorting offices
Handling large volumes of mail
Receiving threatening letters or packages containing white powder
How is cutaneous anthrax treated?
Penicllin Flucloxacillin Clindamycin Ciprofloxacin Metronidazole
What is tinea?
A superficial dermatophyte infection characterised by scaly, inflammatory or non-inflammatory patches
How is tinea spread?
Direct skin to skin contact
In what pattern does tinea expand?
Centrifugal pattern
What is the common name for tinea pedis?
Athlete’s foot
What pathogens most commonly cause tinea?
Trichophyton
Microsporum
Epidermophyton
How is tinea diagnosed?
Potassium hydroxide preparation form a skin scraping
What causes erythema infectiosum?
Human parvovirus virus B19
How is human parvovirus B19 (causing erythema infectiosum) spread?
Blood or blood products
What are the symptoms fo erythema infectiosum?
Fever
Headache
Runny nose
Pruritic rash on the face, torso and extremities
Erythema infectiosum is self limiting and reoslves without complications. T/F?
It is self limiting and IN CHILDREN resolves without complications
Erythema infectiosum can cause an acute cessation of red blood cell production. What problems can this cause?
Transient aplastic crisis
Chronic red cell aplasia
Hydrops foetals
Congenital anaemia
What virus causes hand foot and mouth disease?
Coxsackle virus A16
What age groups are commonly affected by hand foot and mouth disease?
Children and infants
What are the symptoms of hand foot and mouth disease?
Fever Rash Headache Sore throat Oropharyngeal ulcers Loss of appetite
What are the symptoms of measles?
Fever Cough Coryza Conjunctivitis Koplik spots Maculoppaular red rash on face and hairline then spreading to the neck, trunk, arms and legs
What are the possible complications of measles?
Hospitalisation
Pneumonia
Encephalitis (can cause deafness and intellectual disability)
Death due to respiratory and neurological complications
At what site can herpes simplex virus lie latent?
Sensory nerve ganglia
How is herpes simplex virus treated?
Topical/oral/IV acyclovir
At what days in infection is varicella zoster virus contagious?
days 8-21
Varicella zoster virus can cause congenital abnormalities if it is acquired during pregnancy. T/F?
True
High risk adults with varicella. zoster virus infection should be. treatment with acyclovir. Which adults are classified as high risk?
Pregnant
Immunocompromised
Pneumonitis
Reactivation of format varicella zoster virus in what site causes shingles?
Dorsal root ganglia
What is the typical distribution of shingles?
Dermatomal distribution
How is shingles treated?
Pain management with NSAIDs and gabapentin
High risk patients treated with acyclovir
