Week 7 -> infections on a surface Flashcards
Name the mucosal membranes of the body
-Conjunctive, GI, resp, genitourinary
Are mucosal layers sterile?
-They aspire to be but they have microbiota
Name a virus which is skin microbiota
- Papilloma virus
- Herpes virus
Name some skin bacterial microbiota
- S.aureus
- Coag. neg staph
- enterobacteriaciae eg coliforms such as e.coli, k.pneumoniae
Name some fungi which are normal skin microbiota
- yeats and dermatophytes
Name some normal microbiota of the stomach
- H.pylori
- Strep
- Staph
Name some normal microbiota of intestines
- Enterobacteriaciae
- lactobacili
- clostriudium
Name some normal microbiota of the mouth
- Viridans strep
- Neisseriae
- Candida
- lactobacillus
Name some normal microbiota of urethra
-Enterobacteiarcaie
Name some normal microbiota of the vagina
-Lactobacilli
Give an example of an infection which arises from invasion of a surface
-Pharyngitis by Strep pyogenes
What are the mechanisms by which infections arise from a surface?
- Invasion
- Innoculation
- Haemotogenous
- Migration
Give an example of an infection which arises from migration of a surface
-UTI bu e.coli
Give an example of an infection which arises from innoculation of a surface
-Prosthetic joint surgery and coag neg staph
Give an example of an infection which arises from haemotogenous spread of a surface
-Endocarditis and viridans strep
What is the pathogenesis of endocarditis from viridans strep?
- 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
Name a surface infection caused by microbiota not at their usual site
- Cellulitis
- Pharyngitis
- Gastroenteritis
Describe some infections which can occur upon surfaces of medical equiptment
- Intravascular lines can cause phlebitis
- Catheters and UTIs
- Prosthetic joints/valves and staph
- Hickman lines
What is the most likely infectious agent of endocarditis >1year post-op?
-Viridans
What is the most likely infectious agent of endocarditis less than 1 year after op?
-Coag neg staph
How does a bicuspid aortic valve predispose to endocarditis?
-Turbulent flow predisoises to eddys and damage to valves
How does poor dental hygiene predispose to endocarditis
-Increased risk of innoculation
How do pili/fimbrae increase the virulence of pathogens at a surface?
-Increase the chances of adherence
How does biofilm formation increase the virulence of pathogens at a surface?
-Aids attachment and multiplication by producing a slime which evades the immune system and provides risitance to Abx
What is quorum sensing?
-Communication between bacteria via signalling molecules which controls expression of virulence factors, sporulation and biofilm formation
What is the pathway by which micro-organisms cause disease?
-Exposure -> adherence -> invasion -> multiplication -> dissemination
How do you manage infections at a surface?
- Diagnosis and identification of causative organism -> Abx
- Blod cultures if appropriate
- removal of prosthetic material or resection of infection
What is microbiota?
-Microbes which reside on surfaces and in deep layers of the skin
