Microbiology 6: Skin infection Flashcards
What is Staph aureus, what can it infect? toxins produced
STAPH AUREUS
Commensals activated
Or more specific ones: MRSA (not worse infetion, just harder to treat)
\: can produce different toxins: panton valentube leuocidin Exfoliative toxin-cause blister toxic shock syndrome toxin 1 Entertoxin-MRSA can produce that, and if gets into stomach can cause diarrhoae and vomitting
Can cause infection in many other places
What different infectiosn can staph aureus cause?
If subcornea layer of epidermis-impetigo
Folliculitis in hair follicule
Deeper in dermis can cause ecthyma
Can cause absesses
or staphylococcal scaleded skkin syndrome
What is impetigo ?
Often staph aureus -yellow ish, crusty superficial blistering around nose and mouth
Not very severe-but can get worse -impitigisation (impitago on top of extra skin disease (like eczema)
goldten crust is very related to staph aureus
if have exfoliative toxin-cause splitting of skin -> cause blisters full of pus -> Bullous impetigo
What is ecthyma in terms of staph aureus?
Full thickness infection of the dermis -> surface of skin is necrotic and dead
usually caused by infected incest bites/immunocompromised
What are absesses in relation to staph aureus?
pus collection under the skin
What is Staphylococcal scalded skin syndrome?
Most in very young children- similar to boullous impetigo
Staph aureus infection somwhere on body producing exfoliative toxin-> cause splitting of skin, redness all over the body
Abx to treat infection
How can you treat Staph aureus?c
Culture it then usually see if resistant to fludroxicillin-if it is then considered to be MRSA
What is Treponema Pallidum? Presentation?
Spiral shaped bacteria that causes syphilis
used to be very common, Abx killed it, now coming back
Primary . 3-8 weeks
start with painless ulcer at innoculation site (Chancre)–serology will be negative
then Secondary: generalised Rash (spotty red botchy rash-usually palms and soles), lymphadenopahy-disseminated infection. can last a few weeks
can become latent syphillis-no clincal signs-could be transmitted
or can become/rewake as Tertiary-usually years later
Can affect any tissue, usually skin, neuro, vascular
also can go by congenital-acquired before birth
What are the complications of tertiary syphillis?
Cause inflammatory, destructive responses in many places-skin, etc
can cause thoracic aneurysm-dilated aorta
neurosyphillis can come from. Used to be high cause of dementia?
What is congenital syphillis?
Mother ahs syphillis and given to baby
much likelier to miscarry, premature
but if live, develop secondary signs (rashes),
Often develop to tertiary-destructive lesion, neuro issues, bone disease,
Diagnosis of syphillis? Treatment?
Primary-serology negatvie, swap the ulcer
secpndary-serology will be active this time
biopsy of rash-still full of plasma cells
treat with Abx-penicillin
What are the 3 main herpes viruses?
Her[es virus 1 (H. Simplex-mouth), Herpes 2 ( Hepees simplex type 2 ) genital) and herpes 3 (chicken pox (VZV)
all 3 live infect mucroepithelial and lie in nerves in latent part of infection and can rise back out
other notable- Epstein Barr virus, HHV7, CMV (cause mononucleosis)
What is Herpes simplex? presentation
2types: 1around mouth, 2 around genital
present as small round vesicular rash–rise up, fill with pus, then dry up-eczema -leaves after 2 weeks, and leaves, no scarrs
Lives then withhin nerves and can reactivate when immunosupression bit lower
type 1-common around lips/on lips (epescially lower lip)
type 2: tip of penis, sides, labia majora, etc
but doesnt have to be-can occur other places
latency-live on in nerve roots then reactivate
What is eczema Herpeticum?
People with excema have barrier defects-and can easily get staph aureus, or combine with herpes
When combine with Heprpes-get Eczema herpeticum—becomes very extensive, small blisters run down neck and more
What is varicella zoster? presentation,? complication?
Chicken pox causes by VZV-vesciles similar to HSV-usually all over body but centripedal distribution-concentrate on face/body
lesions on and IN mouth as well->
generally making you feel unwell too
can complicate-encephelitis
pneumonia (especially in elderly)
The mortality rate increases in elderly
stress/other illnes-cause rash of chicken pox but ONLY down 1 dermatome -hepes Zoster (shingles)
can be very bullous (blistering)
can be swabbed-and then iwll get better but acyclovir can help
Ophtlamic shingles-painful, serious
What are the common superficial skin fungal infection?
2 types:
Dermatophytes- (eg Trychptyons rubrum)-grow in keratin–> cause Tinea-> Name of clinical presentation. In nail, tinea unguium (yellow crusty nail), Tinea capitis (scalp-), tenia pedis (between toes)
Can be carried by animals or humans
diagnose with samples again-culture or PCR
treat with drugs (usually cream form)-except if in nails and crap
Yeasts-candida-grow on wet humid environements-single cells and buds (like under breasts, vagina, between legs)
Usually cause 1 area involved + satellites lesions
Respond to typical antifungal creams
What cause scabies, clinical presentation, treatment, complication
Sacroptes scabei-small insect (mite)
Female burrows into the skin-into epidermis (stratum corneum)
Key sign to look for is the burrow - very hard to see tho (4mm long)-S shaped squiggly white line with risen dot at end (head of mite) -nothing else causes it so has to be scapies
when scratched hard to see
usually in webs (finger and toes), axilla, between legs, around ass, elbows
after about 4 weeks cause widespread eczema
treatment-insecticide cream-on all body for 12h
need long time of skin to skin contact-
will cause secondary bacterial infections-large cause of kidney failure due to infection
