Infections On The Surface

Question 1

What is a surface

Answer 1

Inter surface between a solid and either a liquid or gas

Question 2

Give examples of human surfaces

Answer 2

SKIN : epithelium , hair and nails

Mucosal surfaces : eg GI , Urinary , respiratory tract

Question 3

Give examples of skin viruses

Answer 3

1. Papilloma

2. Herpes simplex ( cold sores )

Question 4

How do people generally tend to get infections on surface ?

Answer 4

Microbiota

Microorganisms carried on skin and mucosal surfaces are normally harmless or even benefitical. However the transfer to other sites can be harmful.

Question 5

How can microbiota transfer to other sites ?

Answer 5

1. Invasion
2. Migration for example E. coli travels from anus to vagina.
3. Inoculation eg during surgery
4. Haematogenous eg endocarditis

Question 6

What are examples of natural surface infections ?

Answer 6

External : cellulitis , pharyngitis , conjunctivitis , UTI , pneumonia , gastroenteritis

Internal :

Question 7

What is prosthetic valve endocarditis

Answer 7

Endovascular , microbial infection occurring on parts of the prosthetic valve

Question 8

What are causative organisms for prosthetic joint infections ?

Answer 8

Coagulate negative staphylococci

Staphylococcus aures

Question 9

What are causative organisms for cardiac pacing wire endocarditis ?

Answer 9

Coagulate negative staphylococci

Staphylococcus aures

Question 10

Outline the process in the pathogens is of infection at surfaces

Answer 10

1. Adherence to host cells or prosthetic surface
2. Biofilm formation - which invovles the formation of extracellular material such as polysaccharides , nucleic acids which are secreted which produces a slimey layer. This facilitates attachment and produces an ECM.
3. Invasion and multiplication
4. Host response involves pyogenic ( neutrophil number increases ), granulomatous formation ( fibroblasts , lymphocytes and macrophages increase in number which results in nodular inflammatory lesions)

Question 11

What is quorum sensing ?

Answer 11

Quorem sensing bacteria control sporulation , biofilm formation and virulence factors secretion

There are three principles :

1. Quorem sensing bacteria release signalling molecules such as autoinducers which binds to cell surface or cytoplamsic receptors
2. This helps to regulate gene expression.

Question 12

How to manage surface infections ?

Answer 12

1. Antibacterial
2. Remove prosthetic material

3, surgery to resect infected material

4. Want to sterilise tissues

Question 13

What are challenges faced when it comes to management of surface infections ?

Answer 13

Poor antibacterial penetration into biofil,

Low metabolic activity of biofilm microorganisms

Dangers and difficulties of surgery

Question 14

How to prevent surface infections ?

Answer 14

Natural surface : maintain surface integrity eg moisturising

2. Prevent bacterial surface colonisation
3. Removing colonising bacteria

PROSHETIC SURFACES :

1. Prevent contamination
2. Inhibit surface colonisation
3. Removing colonising bacteria