Infections On Surfaces Flashcards
What are microbiota?
The microorganisms that typically inhabit a bodily organ/part
What is a surface?
Interface between a solid and either a liquid or gas
What are mucosal flora of the eye?
Coagulase negative Staphylococci Diphtheroids Saphrophytic Neisseria meningitidis Viridans group streptococci
Common microbiota of nares?
Staph aureus
Common microbiota of the nasopharynx?
Neisseria meningitidis
Streptococcus pneumoniae
Haemophilus influenzae
Common bacteria of the mouth?
Viridans Streptococci Neisseria Veillonella Lactobacillus Acrinmyces Candida albicans Many more
Common bacteria of the stomach?
Helicobacter
Streptococci
Staphylococci
Lactobacilli
Common bacteria of the intestine?
Anaerobic and aerobic streptococci Clostridium Yeasts Bacteroides Lactobacillus Coliforms
Common microbiota of the urethra?
Lactobacilli Enterobacteriaceae Diphtheroids α and non-haemolytic Streptococci Enterococci
How do people get infections from surfaces? Give examples of infections for each one
Invasion - Strep pyogenes, pharyngitis
Migration - E. coli, UTI
Innocuoation - coagulase negative staphylococci, prosthetic joint infection
Haematogenous - viridans Streptococci, endocarditis
Give some examples of prosthetic surface infections
IV lines - sepsis Peritoneal dialysis catheters Cardiac valves Pacing wires Endovascular grafts Ventriculo-peritoneal shunts
Examples of natural external surface infections?
Cellulitis Gastroenteritis Pharyngitis UTI Conjunctivitis Pneumonia
Examples of some common internal surface infections?
Endovascular endocarditis/vasculitis
- viridans Streptococci
- enterococcus faecalis
- Staph aureus
- Candida
Septic arthritis
Osteomyelitis
Empyema
Overall process of pathogenesis of infections at surfaces?
Adherence to host cells/prosthetic surface
Biofilm formation
Invasion and multiplication
Host response
How do bacteria adhere to a surface?
Use pilli or fimbrae
Influenza attaches to cells by haemoggluttin antigen
What is a biofilm?
A slimy matrix produced by bacteria made up of polysaccharides
Nutrients can diffuse in and out
Close proximity of cells in the matrix facilitates exchange of molecular signals that regulate behaviour
Why are infections caused by bacteria with biofilms difficult to treat?
Antimicrobials will only damage outer cell layers so the biofilm community is resistant
In the host response, what is vegetation?
Host response to pathological damage to a site
Low grade inflammatory process caused by the bacteria.
Involves platelets, fibrin and inflammatory cells
Poorly vascularised
Can produce a hole in the surface eg heart valve
What are the main steps in the management of infected surfaces?
Diagnosis
Treatment
Prevention
How do you diagnose an infection on a surface?
Identify infecting organism and its anti-microbial susceptibilities
Take blood cultures
Tissue/prosthetic material sonication to produce a culture
Aims of treatment of an infection at a surface?
How is this done?
Sterilise tissue and reduce bioburden
- antibacterials
- remove prosthetic material
- surgery to resect infected material
What challenges are faced when treating an infected surface?
Poor antibacterial penetration into biofilm
Low metabolic activity of biofilm microorganisms
Risks of surgery
How to prevent an infection on a surface?
Internal surface:
Maintain surface integrity
Prevent bacterial surface colonisation
Remove colonisation of bacteria
External surface:
Prevent contamination
Inhibit surface colonisation
Remove colonising bacteria
