Microbiology 4: Skin infections Flashcards
WHat % of GP consultations in the UK are skin-related?
15%
In which climates are skin conditions most prevalent?
Hot and humid
Which pathogen is responsible for tinea infections
Tricophytum rubrum
What sort of infection is caused by tricophytum rubrum?
Tinea
What sort of pathogen is trycophytum rubrum?
Fungus
Give 3 examples of tinea infections
Tinea capitis
Tinea ungulum
Tinea manu (“ringworm”)
Which pathogen is responsible for causing scabies?
Sarcoptes scabei
Recall the pathophysiology of a scabies infection
Sarcoptes scabei burrows into the infected epidermis to cause a Type IV DTH reaction
Give 3 common sites for scabies burrows
Groin
Axilla
Anticubital fossae
Recall the main symptom of a scabies infection and how long the latent period is before symptoms are seen
Widespread erythrematous rash
4 week latent period
What classification of bacterium is S aureus?
G+ coccus
Recall the 4 toxins produced by S aureus
PVL
Exfoliative toxin
TSS1
Enterotoxin
What is the result of PVL production by S aureus?
Causes necrotising infection
What is the result of exfoliative toxin production by S aureus?
Blisters
Recall 3 symptoms of S aureus infection?
Skin infection
Severe pneumonia
Sepsis
What is impetigo?
An S aureus infection of the subcorneal layer of the epidermis
Recall the appearance of imeptigo
Yellowish with golden crust, eroded base
In what subset of the population is bullous impetigo most common?
Neonates
What is ecythema?
Full thickness involvement of the epidermis in an S aureus infection
What is the result of exfoliative-toxin productioon by S aureus?
Staphlococcal Scalded skin Syndrome
Recall the pathophysiology of staphylococcal scalded skin syndrome
S aureus releases exfoliative toxin into the bloodstream at wound site
–> systemic infection –> widespread erythema
Differentiate SSSS and toxic epidermal necrolitis
SSSS does not infect the mucous membranes but TEN does
What sort of pathogen is treponema pallidum?
G- bacterium
What is syphillis caused by?
Treponema pallidum
Recall the duration of each of the phases of syphillis infection
Primary = 3-8 weeks Secondary = 6-12 weeks Tertiary = years later
Recall the main symptoms of the primary phase of syphillis
Chancre (painless ulcer) in genital/ oral area
Recall the symptoms of secondary syphillis
Generalised rash, lymphadenopathy and flu-like illness
Describe the rash of secondary syphillis
Maculopapular and erythrematous
Which body systems are affected by tertiary syphillis?
Skin
CNS
PNS
CVS
What is the first-line treatment for congenital syphillis?
Penicillin
Recall which serotypes of HHV are known as EBV, VZV and CMV
EBV = HHV4 VZV = HHV3 CMV = HHV5
Recall which types of HSV cause oral and genital herpes
Oral = type 1 Genital = type 2
Which cells are infected in an HSV infection?
Neurons
Which pathogen commonly infects at defective skin barriers due to eczema?
HSV –> eczema herpeticum
What disease is produced by herpes spreading to the brain?
Herpes encephalitis
Which serotype of HHV is associated with Kaposi’s sarcoma?
HHV8
Where does VZV have latency?
Dorsal root ganglia
Recall a virus that can cause non-cardiac chest pain
VZV when it is reactivated in shingles
How does treatment of VZV differ in shingles that does/ does not affect CNV?
When CNV is infected you get face involvement so acyclovir is given IV rather than orally so as to avoid blindess
