Session 7 - Infection on Surfaces Flashcards Preview

Semester 3 - Infection > Session 7 - Infection on Surfaces > Flashcards

Flashcards in Session 7 - Infection on Surfaces Deck (50)
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1
Q

What is a surface?

A

• Interface between a solid and either a liquid or a gas

2
Q

What are the two main surfaces of the body?

A
  • Skin

* Mucosal surface

3
Q

Give three aspects of skin surfaces

A
  • Epithelim
    • Hair

Nails

4
Q

Give three aspects of muscosal surfaces

A
  • Conjunctival
    • Gastrointestinal
    • Respiratory
    • Genitourinary
5
Q

What are microbiota also known as?

A

Commensals

6
Q

What are microbiota?

A

• Micro-organisms carried on skin and mucosal surfaces

Harmless, or even beneficial

7
Q

When can microbiota be harmful?

A
  • When they transfer to a distant site

* Immunodeficiency

8
Q

Give four methods by which people get infections?

A
  • Invasion - Strep Pyogenes (Pharyngitis)
    • Migration - E.coli (UTI)
    • Inoculation - Coagulase negative staphylocoocus (prosthetic joint infection)
    • Haematogenous - Strep viridians (endocarditis
9
Q

Give two viruses normally found on the skin

A
  • Papilloma

* Herpes simplex

10
Q

Give three types of gram positive bacteria carried on the skin

A
  • Staphylococcus aureus
    • Coagulase negative staphylococci
    • Corynebacterium
11
Q

Give one gram negative bacteria found on the skin

A

Enterobacteriase (Faecal bacteria)

12
Q

Give two types of fungi found on the skin

A
  • Yeasts

* Dermatophytes (cause skin infection)

13
Q

Give a type of parasite found on the skin

A

Mites

14
Q

Give three types of surface which can get infected

A
  • External surface
    • Internal surface
    • Prosthetic surface infections
15
Q

Give three types of infection of external surface infection

A
  • UTI
    • Gastroenteritis
    • Cellulitis
16
Q

Give three types of internal surface infection

A
  • Endovascular
    • Septic arthritis
    • Osteomyelitis
17
Q

Give three areas of vulnerability for prosthetic surface infection

A
  • Intravascular lines
    • Prosthetic joints
    • Cardiac valves
18
Q

What is native valve endocarditis?

A

• Inflammation and infections of valve of the hear

19
Q

What is the bacteria which causes native valvular endocarditis? Where is it found?

A
  • Viridions Streptoccoci

* Gums and teeth, usually

20
Q

How can endocarditis be caused?

A
  • Poor dental hygiene
    • Bacteria enter circulation from gums
    • Bacteria attach to hear valve
21
Q

Who is particularly susceptible to endocarditis?

A
  • People with abnormal valves

* Blood turbulent and slowed as moves through valve

22
Q

What is the bacteria which causes prosthetic valve endocarditis?

A

• Coagulase negative staphylococci (found on skin of surgeons!)

23
Q

What organism causes prosthetic joint infection?

A
  • Coagulase negative staphylococci

* Staphylococcus aureus

24
Q

Why are prosthetic joint infections dangerous?

A
  • Poor blood supply

* Hard for antibiotics to treat

25
Q

What two organisms cause pacing wire endocarditis?

A

• Coagulase negative staphylococci

Staphylococcus aureus

26
Q

Outline the four main steps of pathogenesis of infection at surfaces

A
  • Adherence to host cells or prosthetic surface
    • Biofilm formation
    • Inflammation and multiplication
    • Host response
27
Q

What are two kinds of host response?

A

• Pyogenic (neutrophils -> Pus)

Granulomatous (fibroblasts, lymphocytes, macrophages -> Nodular infammatory lesions)

28
Q

How do bacteria adhere to host cell membrane surfaces?

A

• Pili or fimbriae extend and allow them to connect

29
Q

What are the four stages of biofilm develpment?

A
  • Initial attachment:
    • Irreversible attachment:
    • Maturation I:
    • Maturation II:

Dispersion:

30
Q

What occurs in initial attachment?

A

• Bacteria attach via van der waals forces

31
Q

What is the primary aim in the diagnosis of infection?

A

• Identifying infecting organism and its antimicrobial susceptibilities

32
Q

Give two challenges to treatment which could be discovered upon identification of organisms

A
  • Ädherent organsims

* Low metabolic state/small colony variants

33
Q

What two ways can bacteria be identified?

A
  • Blood cultures

* Tissue/prosthetic material sonication (supersonic loosening) and culture

34
Q

How can you tell if a central line is infected?

A
  • Flushing drugs causes pyrexia

* Implies drug has washed part of central lines biofilm into blood stream

35
Q

What are the two main aims of treatment of a surface infection?

A
  • Sterilise tissue

* Reduce bioburden

36
Q

Give three methods of sterilising tissue and reducing bioburden

A
  • Antibacterials
    • Remove prosthetic material
    • Surgery - Resect infected material
37
Q

Give three challenges of infection management

A
  • Poor antibacterial penetration into biofilm
    • Low metabolic activity of biofilm micro-organisms

Dangers/difficulties of surgery

38
Q

Give three methods of preventing infection of natural surfaces

A
  • Maintain surface integrity
    • Prevent bacterial surface colonisation
    • Remove colonising bacteria
39
Q

Give three methods of preventing infection of prosthetic surfaces

A
  • Prevent contamination (incorporate substances such as Ag to prevent infection)
    • Inhibit surface colonisation
    • Remove colonising bacteria
40
Q

Describe Cellulitis

A

Infection of deeper layer of skin and underlying tissue
Usually seen on legs
Skin will be red, painfully swollen and hot
– can causes septicaemia

41
Q

What causes cellulitis?

A

Group A streptococcus or staphylococcus aureus

– enters through damaged skin

42
Q

Who is more vulnerable to cellulitits?

A

People with athletes foot of eczema

– enters though small breaks or cracks in skin

43
Q

Describe pharyngitis

A

Causes a sore throat due to inflammation of the oropharynx.

Leads to sore throut, fever, enlarged lymph nodes, cough, headache, difficulty or pain when swallowing

44
Q

What causes pharyngitis?

A

Usually has a viral cause but can be due to group A streptococcus

45
Q

What are some complications of pharyngitis?

A

Tonsilitis
Ear infection
Sinus infection
Throat and peritonsilar abscesses

46
Q

Describe conjunctivitis

A

Pink eye, with pus or watery discharge and crust on the eyelashes. Inflammation of the conjunctiva.

47
Q

What causes conjunctivitis?

A

Usually has a viral cause (adenovirus) but most are treated with antibiotics despite the low incidence of bacterial cause.

48
Q

What can cause endocarditis of a native cardiac valve?

A

Viridans streptococci

49
Q

What can cause endocarditis of a prosthetic valve?

A

Coagulase negative staphylococci

50
Q

What causes prosthetic joint infections?

A

Coagulase negative staphylococci

Staphylococcus aureus