What is a surface?
Interface between a solid and either a liquid or gas.
What are some nautral surfaces that can carry infections?
Surfaces on the human body:
- Mucosal surfaces
What are some microorganisms that live on the skin?
- Human Papilloma Virus
- Herpes simplex
- Staphylococcus aureus
What are some mucosal flora present on the eye?
- Coagulase negative staphylococci
- Neiserria species
What are some muscosal flora present in the nares and nasopharynx?
- Staphylococcus aureus
- Neisseria meningitidis
- Streptococcus pneumoniae
- Haemophilus influenzae
What are some mucosal flora present in the mouth?
What are some mucosal flora present in the stomach?
What are some mucosal flora present in the intestine?
- Aerobic and anaerobic streptococci
What are some mucosal flora present in the urethra?
- Alpha and non-haemolytic streptococci
What are some mucosal flora present in the vagina?
- Enterococcus faecali
What is the purpose of microorganisms on skin and mucosal surfaces?
- Normally harmless and can be beneficial
- They take up space and nutrients, making it more difficult for malignant pathogens to grow on the skin
How do people get infections from normal flora?
- Streptococcus pyogenes causing pharyngitis
- E. coli causing UTI
- coagulase negative staphylococcus causing prosthetic joint infection
Haematogenous (gets into the blood)
- viridans streptococcus endocarditis
What are some examples of external nautral surface infections?
What are some examples of internal natural surface infections?
- Septic arthritis
- Empyema (collection of pus in a cavity i.e. pleural cavity)
What are some examples of prosthetic surface infections?
- Intravascular lines
- Periotneal dialysis catheters
- Prosthetic joints
- Cardiac valves
- Pacing wires
- Endovascular grafts
- Ventriculo-peritoneal shunts
What is the process of pathogenesis of infection at surfaces?
- Adherence to host cells or prosthetic surface
- Formation of a biofilm
- Invasion and multiplication
- Host response (normal infection response)
What is a biofilm?
A thin but strong layer of slime-like substance that adheres to a solid surface. Biofilms also contain a community of bacteria and other microorganisms.
What is the importance of a biofilm?
It allows for bacteria to grow on either a natural or prosthetic surface.
This makes it easier for a bacteria to spread from a surface to a host, leading to an infection.
How can infections on natural surfaces be prevented?
- Maintain surface integrity
- Prevent bacterial surface colonisation
- Remove colonising bacteria
How can infections on prosthetic surfaces be prevented?