1b Infections and Infestations of the Skin Flashcards
What is panton valentine leukocidin?
- It is a beta-pore forming toxin released by Staphylococcus aureus
- Increased morbidity, mortality, trasmissability
- Painful, multi-site, recurrent, present in contacts
What are the extracutaneous presentations of panton valentine leukocidin (3)?
- Necrotising fasciitis
- Necrotising pneumonia
- Purpura fulminans
What is the presentation?
- Purpura fulminans
What is the presentation?
- Necrotising fasciitis
A patient presents with the following symptoms:
What is the most likely diagnosis?
- Panton valentine leukocidin releasing staphylococcus aureus
What are the risks of acquiring panton valentine leukocidin releasing staphylococcus aureus (5Cs)?
- Close contact
- Contaminated items
- Crowding
- Cleanliness
- Cuts
How is panton valentine leukocidin releasing staphylococcus aureus managed (4)?
- Abx (often tetracycline)
- Nasal ointment (mupirocin)
- Chlorhexidine body wash
- Treat contacts
What is the presentation?
- Folliculitis (follicular erythema; sometimes pustular)
May be infectious or non-infectious (in HIV)
A patient presents with the following symptoms:
What is the most likely diagnosis?
- May be infectious (Staphylococcus aureus, particularly strains expressing panton valentine leukocidin (PVL))
OR
- Non-infectious (in HIV)
How is folliculitis managed?
- Antibiotics (usually flucloxacillin or erythromycin)
- Incision and drainage is required for furunculosis
What is the presentation?
What is the cause?
- Pseudomonal folliculitis
- Staphylococcus aureus from hot tub, swimming pool, depilatories, wet suits
What is a furuncle?
- A furuncle is a deep follicular abscess involving one follicle
What is a carbuncle?
- A carbuncle is a deep follicular abscess involving several adjacent follicles
More likely to lead to complications such as cellulitis and septicaemia than a furuncle
What is the presentation?
- Cellulitis
What is the cause of cellulitis (2)?
- Streptococcus pyogenes
- Staphylococcus aureus
How is cellulitis managed (1)?
- Systemic antibiotics
What is the presentation?
-
Impetigo
- Superficial bacterial infection, stuck-on, honey-coloured crusts overlying an erosion
What is the cause of impetigo?
- Streptococci (non-bullous)
- Staphylococci (bullous)
Impetiginisation: occurs in atopic dermatitis-> superimposed infection -> gold crusting
How is impetigo managed (1)?
- Topical +/- systemic antibiotics
What is the presentation?
-
Ecthyma
- Severe form of streptococcal impetigo
- Thick crust overlying a ‘punch out’ ulceration surrounded by erythema
- Usually on lower extremities
A patient presents with the following symptoms:
What is the diagnosis?
- Staphylococcal Scalded Skin Syndrome (SSSS) due to exfoliative toxin
Neonates, infants or immunocompromised adults (In neonates, kidneys are immature so cannot excrete the exfoliative toxin quickly)
A patient presents with the following symptoms:
* Fever > 38.9oC
* Hypotension
* Diffuse erythema
* Involvement of ≥ systems: GI, CNS, renal, hepatic, muscular
* Mucous membranes (erythema)
* Hematologic (platelets < 100 000/mm3)
What is the diagnosis?
- Toxic shock syndrome due to Group A Staphylococcus aureus strain that produces pyrogenic exotoxin TSST-1
What is the presentation?
-
Necrotising fascitis
- Initial dusky induration (usually of a limb), followed by rapid painful necrosis of skin, connective tissue and muscle.
What is the cause of necrotising fascitis?
- Usually synergistic: streptococci, staphylococci, enterobacteriacee and anaerobes > Blood and tissue cultures can determine organisms and sensitivities.
A patient presents with the following symptoms:
What is the diagnosis?
Secondary syphillis
- begins 50 days after chancre
What are the features of secondary syphillis?
- Malaise, fever, headache, pruritus, loss of appetite, iritis
- ‘Great mimicker’ - low threshold for testing- strong index of suspicion required
- Rash (88-100%) -Pityriasis rosea-like rash
- Alopecia (‘moth-eaten’)
- Mucous patches
- Lymphadenopathy
- Residual primary chancre
- Condylomata lata
- Hepatosplenomegaly
What is Lues maligna?
- Rare manifestation of secondary syphilis
- Pleomorphic skin lesions with pustules, nodules and ulcers with necrotising vasculitis
- More frequent in HIV manifestation
A patient presents with the following symptoms:
What is the diagnosis?
Tertiary syphillis
What are the features of tertiary syphillis?
- Gumma Skin lesions - nodules and plaques
> Extend peripherally while central areas heal with scarring and atrophy
> Mucosal lesions extend to and destroy the nasal cartilage
> Cardiovascular disease
> Neurosyphilis (general paresis or tabes dorsalis)
A patient presents with the following symptoms:
What is the diagnosis?
-
Lyme disease
- Annular erythema from Borrelia infected tick bite
Borreliosis; 1-30 days from infection
* Neuroborreliosis
* Arthritis
* Carditis
A patient presents with the following symptoms:
What is the diagnosis?
- Oral lesion caused by herpes simplex virus (HSV-1)
HSV-1 is mainly transmitted by oral-to-oral contact to cause oral herpes (which can include symptoms known as “cold sores”), but can also cause genital herpes. HSV-2 is a sexually transmitted infection that causes genital herpes. Both HSV-1 and HSV-2 infections are lifelong.
A patient presents with the following symptoms:
What is the diagnosis?
- Genital lesion caused by herpes simplex virus (HSV-2)
HSV-1 is mainly transmitted by oral-to-oral contact to cause oral herpes (which can include symptoms known as “cold sores”), but can also cause genital herpes. HSV-2 is a sexually transmitted infection that causes genital herpes. Both HSV-1 and HSV-2 infections are lifelong.
A patient presents with the following symptoms:
What is the diagnosis?
-
Eczema herpeticum
- Monomorphic, punched out erosions (excoriated vesicles)
It’s an emergency!
A patient presents with the following symptoms:
What is the diagnosis?
-
Herpetic whitlow
- HSV (1>2) infection of digits - pain, swelling and vesicles (vesicles may appear later)
Misdiagnosed as paronychia or dactylitis
Often in children
A patient presents with the following symptoms:
What is the diagnosis?
- Candidiasis (Candida Albicans)
A patient presents with the following symptoms:
What is the diagnosis and what is it caused by?
-
Scabies caused by sarcoptes species:
- Female mates, burrows into epidermis, lays eggs and dies
A patient presents with the following symptoms
*black crusty lesions
*redness and swelling
*Hx of diabetes mellitus
What is the diagnosis?
Mucormycosis
A patient presents with the following symptoms:
- Hyper/hypopigmentation
What is the diagnosis?
Pityriasis versicolor
What is a Kerion?
An inflammatory fungal infection that may mimic a bacterial folliculitis or an abscess of the scalp; scalp is tender and patient usually has posterior cervical lymphadenopathy
- Frequently secondarily infected with Staphylococcus aureus
What is tinea capitis and what is it caused by?
Scalp ringworm- caused by Trichophyton tonsurans
What species causes the most fungal infections and give example of what it causes.
Trichophyton rubrum e.g. tinea pedis (athlete’s foot) and onychomycosis
What is the Id reaction?
- Aka Dermatophytid reactions
- Inflammatory reactions at sites distant from the associated dermatophyte infection
- May include urticaria, hand dermatitis, or erythema nodosum
- Likely secondary to a strong host immunologic response against fungal antigens
