skin infections

Question 1

how skin microbiome helps protect against infection
-psseudomonas
-s.aureus

Answer 1

-pseudomonas on skin helps protect against s.aureus

Question 2

common skin bactera
1) staphlococcus (s. auareus)
2) streptococcus (s. pyogenes)

-does it produce catalase
-does it survive well in environment
-what colonies does it form

Answer 2

both gram positive
1) produce catalase. survive well in environment. produces cream colonies
2) don’t produce catalase. don’;t survive well in environement. produces grey translucent colonies

Question 3

spreading responses severity
1) impetigo
2) erysipelas
3) cellulitus

Answer 3

1) less severe
2) average
3) most severe

Question 4

facts about acne
-casued by pathogen cultibacterium acnes
-type of pathogen
-how does it stimulate inflammation
-how is it treated

Answer 4

pathogen part of normal skin micobiome
-opportunistic pathogen
blockage of pores promotes bacterial growth. stimulates inflammation
treated with antibiotics which increases resistence

Question 5

entry of pathogens
-exogenous
-endogenous

Answer 5

-from outisde e..g wounds, bites. may already be part of skin microbiome. trauma can be mild e..g athletes foot. or major surgerys or burn victums.
extracellular bacteria- humoural pathway

-from within e.g. carried by lymph or blood. the skin can become infected by microorganisms that spread from another infected internal site.
intracellular - cell mediated

Question 6

sources of endogenous skin infection

Answer 6

1) direct extension
2) bloodstream spread

Question 7

spread and multiplication of
1) straptococcus .aureus
2) streptococcus .pyogenes (causes cellulitis)

Answer 7

1) infections of skin tend to localize, forming abscesses
2) infections spread more extensivly through tissues causing cellulitis, casue more severe infections

Question 8

s. aureus
-how does it not always caused skin disease
-example

Answer 8

requires specific virulence factors
example= scalded skin syndrome (SSSS) which is a rare infection in babies

Question 9

s. pyogenes
-causes range of diseases (skin infections and scarlet fever)
-who does it infect and what inate cells does it kill

-what casues rash in scarlet fever

Answer 9

-only infects humans and can kill neutrophils
-in scarlet fever the rash is due to the toxin released by bacteria. it binds and activates many T cells leading to the symptoms

Question 10

example of viral skin infections
1)shingles
-same as what pox virus
-who is it common in
-why does it re occur

Answer 10

-same virus as chicken pox
-occurs in elderly who have already had chicken pox
-when the body is clear of chicken pox part of the virus hides and can reactivate

Question 11

what is poxvirus
example of pox virus
-small pox
-m-pox

Answer 11

large DNA viruses that replicate in the cell cytoplasm. small pox- vaccines have eradicated it
mpox- can be prevented with a vaccine. usually self limiting.

Question 12

another skin infection:
1)leprosy
-features of infection
-what animal can it be grown in
-how symptoms occur and treatment

Answer 12

-historically been feared and resulted in more social stigmatization than other infecious diseases.
-grown in armadillos
-symptoms are patches of discoloured skin/ numbness. symptoms due to nerve damage
-treatment with antibitics

Question 13

extreme forms of lepracy
1) tuberculoid
2) lepromatous
-how does it affect the immune response,
-how it affects bacteria

Answer 13

1) cell damaging immune response, few organisms
2) no immune response, massive bacterial load

Question 14

components of skin pathogens that increases ability to penetrate skin and establish site

Answer 14

production of enzymes which dedrade extracellular matrix components