Infection: Infections on Surfaces Flashcards
What is a surface?
The interface between a solid and either a liquid or a gas
What are commensals?
Microorganisms carried on skin and mucosal surfaces that are normally harmless or even beneficial.
They only cause problems when they transfer to other sites
What are the different modes of transmission causing people to get infections?
Invasion - direct
Migration - bacteria travelling from one location to another where it isnt supposed to be
Innoculation - bacteria growing on a prosthetic joint
Haematogenous - spread via the blood
Give some examples of natural surface infections
External: UTI, pneumonia, cellulitis
Internal: endocarditis, osteomyelitis
Give some examples of prosthetic surface infections
IV lines, dialysis catheters, cardiac valves, prosthetic joints
What types of MOs cause prosthetic valve endocarditis?
Less than 1 year post op = staph aureus, candida, viridans strep
More than 1 year post op: coag neg staph
What type of MOs cause prosthetic joint infections?
Staph aureus or coag neg staph
What type of MOs cause cardiac pacing wire endocarditis?
Staph aureus or coag neg staph
What is the process that leads to infection at surfaces?
Adherence to host cells or prosthetic surface (pili or fimbrae help bind to surface)
Biolfilm formation (bacteria produce a biofilm which protects them from destruction from host and antibacterials)
Invasion and multiplication
How can infections at surfaces be prevented?
Natural surfaces: maintain integrity, prevent colonisation, remove bacteria
Prosthetic surfaces: prevent contamination, inhibit surface colonisation, remove bacteria
How do we manage infected surfaces?
Identify the infecting organism - blood culture or tissue/prosthetic culture
Use antibacterials
Remove the prosthetic
May need surgery to resect the infected material
