Week 7 -> infections on a surface

Question 1

Name the mucosal membranes of the body

Answer 1

-Conjunctive, GI, resp, genitourinary

Question 2

Are mucosal layers sterile?

Answer 2

-They aspire to be but they have microbiota

Question 3

Name a virus which is skin microbiota

Answer 3

• Papilloma virus

- Herpes virus

Question 4

Name some skin bacterial microbiota

Answer 4

• S.aureus
• Coag. neg staph
• enterobacteriaciae eg coliforms such as e.coli, k.pneumoniae

Question 5

Name some fungi which are normal skin microbiota

Answer 5

• yeats and dermatophytes

Question 6

Name some normal microbiota of the stomach

Answer 6

• H.pylori
• Strep
• Staph

Question 7

Name some normal microbiota of intestines

Answer 7

• Enterobacteriaciae
• lactobacili
• clostriudium

Question 8

Name some normal microbiota of the mouth

Answer 8

• Viridans strep
• Neisseriae
• Candida
• lactobacillus

Question 9

Name some normal microbiota of urethra

Answer 9

-Enterobacteiarcaie

Question 10

Name some normal microbiota of the vagina

Answer 10

-Lactobacilli

Question 11

Give an example of an infection which arises from invasion of a surface

Answer 11

-Pharyngitis by Strep pyogenes

Question 12

What are the mechanisms by which infections arise from a surface?

Answer 12

• Invasion
• Innoculation
• Haemotogenous
• Migration

Question 13

Give an example of an infection which arises from migration of a surface

Answer 13

-UTI bu e.coli

Question 14

Give an example of an infection which arises from innoculation of a surface

Answer 14

-Prosthetic joint surgery and coag neg staph

Question 15

Give an example of an infection which arises from haemotogenous spread of a surface

Answer 15

-Endocarditis and viridans strep

Question 16

What is the pathogenesis of endocarditis from viridans strep?

Answer 16

• Viridans strep enters bloodstream (eg during dental work)
• Subcutaneous tissue of heart contains finbronectin which has a receptors to which viridans strep can bind
• Any break in the endotheluim exposes the receptor

Question 17

Name a surface infection caused by microbiota not at their usual site

Answer 17

• Cellulitis
• Pharyngitis
• Gastroenteritis

Question 18

Describe some infections which can occur upon surfaces of medical equiptment

Answer 18

• Intravascular lines can cause phlebitis
• Catheters and UTIs
• Prosthetic joints/valves and staph
• Hickman lines

Question 19

What is the most likely infectious agent of endocarditis >1year post-op?

Answer 19

-Viridans

Question 20

What is the most likely infectious agent of endocarditis less than 1 year after op?

Answer 20

-Coag neg staph

Question 21

How does a bicuspid aortic valve predispose to endocarditis?

Answer 21

-Turbulent flow predisoises to eddys and damage to valves

Question 22

How does poor dental hygiene predispose to endocarditis

Answer 22

-Increased risk of innoculation

Question 23

How do pili/fimbrae increase the virulence of pathogens at a surface?

Answer 23

-Increase the chances of adherence

Question 24

How does biofilm formation increase the virulence of pathogens at a surface?

Answer 24

-Aids attachment and multiplication by producing a slime which evades the immune system and provides risitance to Abx

Question 25

What is quorum sensing?

Answer 25

-Communication between bacteria via signalling molecules which controls expression of virulence factors, sporulation and biofilm formation

Question 26

What is the pathway by which micro-organisms cause disease?

Answer 26

-Exposure -> adherence -> invasion -> multiplication -> dissemination

Question 27

How do you manage infections at a surface?

Answer 27

• Diagnosis and identification of causative organism -> Abx
• Blod cultures if appropriate
• removal of prosthetic material or resection of infection

Question 28

What is microbiota?

Answer 28

-Microbes which reside on surfaces and in deep layers of the skin