Microbiology - Dermatology Flashcards
what is virulence?
the ability of an organism to cause disease within a host
name five virulence factors
adhesin impedin invasin aggressin modulin
what are adhesins?
bacterial cell surface components that help the organism stick to host tissues
what are invasins?
components that enable organisms to invade host tissue
what are impedins?
components that help the organism avoid the immune response in host tissue
what are aggressins?
components that cause direct damage to host tissue and immune cells, affecting the hosts ability to cope with disease in the future
what are modulins?
components that cause indirect damage to the host by turning the immune system on itself
true or false: the nasal strain of staph aureus can protect the mucosa
true
true or false: staph epidermidis can occupy up to 100% of our skin
true
where is the most common entry or staph aureus into the body?
the nose
name the three main important virulence factors of staph aureus infection
fibrinogen binding protein
leukocidin
TSST 1
what type of virulence factor is fibrinogen binding protein?
adhesin
what does leukocidin do?
kills leukocytes
true or false: every strain of staph aureus carries every virulence factor
false
which two severe skin diseases is leukocidin associated with?
necrotising fasciitis
recurrent furunculosis
true or false: leukocidin is more virulent in hospital acquired MRSA than community acquired
false
name a superantigen released by MRSA
TSST 1
what does TSST 1 cause?
toxic shock syndrome
how do superantigens avoid specific T cell activation?
bind to MHC II complex on the outside (not how they conventionally bind)
name three skin infections caused by strep pyogenes
impetigo
cellulitis
necrotising fasciitis
how does the lancefield system classify different subtypes of strep pyogenes?
M protein
which two virulence factors are particularly important as adhesins for strep pyogenes?
hyaluronic acid
CD44 positive keratinocytes
true or false: the bigger the capsule the less virulent an organism is
false
where does impetigo usually affect?
the face
where in the body is strep pyogenes normally found?
the throat
which strain of staph aureus commonly produces abscesses and boils, usually affecting numerous family members at once/
PVL (panton valentine leukocidin)
which group of strep causes throat and severe skin infections?
group A
which bacteria causes impetigo?
staph aureus
group A strep
which bacteria tends to cause necrotising fasciitis?
group A strep (strep pyogenes)
what is the treatment of choice for staph aureus?
flucloxacillin
what is the treatment of choice for strep pyogenes?
penicillin
what is necrotising fasciitis?
bacterial infection spreading under the skin into the fascia
what is the nickname for necrotising fasciitis?
flesh eating bacterial disease
true or false: type I necrotising fasciitis is caused by group A strep
false
type I = mixed anaerobes and coliforms
II = group A strep
what is the most common skin fungal infection caused by?
ringworm
what is another name for athlete’s foot?
tinea pedis
how is dermatophyte infection caused?
fungus enters abraded skin and infects keratinised tissue, provoking inflammation and outward lesioning
which organism is the most common cause of dermatophyte infection?
trichophyton rubrum
how are small areas of dermatophyte infection treated?
clotrimazole cream
nail paint
how are dermatophyte scalp infections treated?
terbinafine oral
itraconzole oral
which parasite causes scabies?
sarcoptes scabiei
how long does incubation of scabies take?
up to six weeks
how is scabies treated?
malathion lotion overnight
benzyl benzoate in adults
what virus cause chickenpox and shingles?
varicella zoster
where does varicella zoster become dormant following chickenpox?
dorsal root ganglia of the spine
true or false: chickenpox can cause pneumonitis and encephalitis
true
what is ramsay hunt syndrome?
reactivation of varicella zoster in CN VII
causes vesicles and pain in the auditory canal and throat
what does herpes simplex virus cause around the mouth?
primary gingivostomatitis
extensive ulceration
what is the treatment of choice for varicella zoster and herpes simplex virus?
aciclovir
which virus tends to cause warts?
human papilloma virus
which treatment is effective for warts?
salicylic acid
which bacterium causes syphilis?
treponema pallidum
how is syphilis tretaed?
penicillin injections
