Infections On The Surface Flashcards
What is a surface
Inter surface between a solid and either a liquid or gas
Give examples of human surfaces
SKIN : epithelium , hair and nails
Mucosal surfaces : eg GI , Urinary , respiratory tract
Give examples of skin viruses
- Papilloma
2. Herpes simplex ( cold sores )
How do people generally tend to get infections on surface ?
Microbiota
Microorganisms carried on skin and mucosal surfaces are normally harmless or even benefitical. However the transfer to other sites can be harmful.
How can microbiota transfer to other sites ?
- Invasion
- Migration for example E. coli travels from anus to vagina.
- Inoculation eg during surgery
- Haematogenous eg endocarditis
What are examples of natural surface infections ?
External : cellulitis , pharyngitis , conjunctivitis , UTI , pneumonia , gastroenteritis
Internal :
What is prosthetic valve endocarditis
Endovascular , microbial infection occurring on parts of the prosthetic valve
What are causative organisms for prosthetic joint infections ?
Coagulate negative staphylococci
Staphylococcus aures
What are causative organisms for cardiac pacing wire endocarditis ?
Coagulate negative staphylococci
Staphylococcus aures
Outline the process in the pathogens is of infection at surfaces
- Adherence to host cells or prosthetic surface
- 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.
- Invasion and multiplication
- Host response involves pyogenic ( neutrophil number increases ), granulomatous formation ( fibroblasts , lymphocytes and macrophages increase in number which results in nodular inflammatory lesions)
What is quorum sensing ?
Quorem sensing bacteria control sporulation , biofilm formation and virulence factors secretion
There are three principles :
- Quorem sensing bacteria release signalling molecules such as autoinducers which binds to cell surface or cytoplamsic receptors
- This helps to regulate gene expression.
How to manage surface infections ?
- Antibacterial
- Remove prosthetic material
3, surgery to resect infected material
- Want to sterilise tissues
What are challenges faced when it comes to management of surface infections ?
Poor antibacterial penetration into biofil,
Low metabolic activity of biofilm microorganisms
Dangers and difficulties of surgery
How to prevent surface infections ?
Natural surface : maintain surface integrity eg moisturising
- Prevent bacterial surface colonisation
- Removing colonising bacteria
PROSHETIC SURFACES :
- Prevent contamination
- Inhibit surface colonisation
- Removing colonising bacteria