Infections On Surfaces, Biofilms Flashcards
What is a surface?
An interface between a solid and either a liquid or gas
In terms of the infection model, what are 2 kinds of surfaces?
Give 3 examples of each
Skin;
- Epithelium
- Hair
- Nails
Mucosal surfaces;
- Genitourinary
- Respiratory
- Gastrointestinal
- Conjuctival
Name 4 types of micro-organisms found on skin
Viruses
Bacteria
Fungi
Parasites (Mites)
List 5 ways people can get surface infections
- Microbiota
- Invasion
- Migration
- Innoculation
- Haematogenous
What are 2 kinds of surface infections
Natural and prosthetic
What are the 2 kinds of Natural surface infections
Give 4 examples of each
External;
- Cellulitis
- Pharyngitis
- Conjunctivitis
- UTI
Internal;
- Endocarditis
- Vasculitis
- Osteomyelitis
- Empyema (Collection of pus in pleural cavity)
List 4 examples of prosthetic surfaces where infections can occur
- Cardiac valves
- Pacing wires
- Prosthetic joints
- Peritoneal dialysis catheters
Name causative organisms for;
- Prosthetic valve endocarditis> 1 year post-op
- Prosthetic valve endocarditis< 1 year post-op
> 1 year post op: viridans Streptococci, Staph aureus
<1 year post op: Coagulase negative staphylococci
Name 2 causative organisms for Prosthetic joint infections
- Staphylococcus aureus
- Coagulase negative staphylococci
Name 2 causative organisms for Pacing wire endocarditis
- Staphylococcus aureus
- Coagulase negative staphylococci
What 4 processes are involved in the pathogenesis of surface infections?
- Adherence to host cells/ prosthetic surface
- Biofilm formation
- Invasion and multiplication
- Host response (Pyogenic OR Granulomatous)
(Pyogenic means neutrophils-> Pus)
How can bacteria bind to surfaces/ surface receptors
Via Pili (Thin strands of protein)
What is a biofilm?
What is biofilm formation?
A microbial community attached to a surface and encase in an ECM of microbial origin
A process where microorganisms irreversibly attach to and grow on a surface, producing extracellular substances that facilitate attachment and matrix formation
What is Quorum sensing?
What is a Quorum?
(In regards to surface infections)
Ability to detect and respond to cell population density by gene regulation
Quorum: Minimum amount of bacteria needed to make a biofilm
Name 3 principles of Quorum sensing
Name 3 things controlled by Quorum sensing
Principles;
- Signalling molecules
- Cell surface/ Cytoplasmic receptors
- Gene expression
Controls;
- Sporulation
- Biofilm formation
- Virulence factor secretion
In managing a surface infection;
- What are 2 aims of diagnosis?
- What are 2 methods of diagnosis?
Aims;
- Identify infecting organism
- and it’s antimicrobial susceptibilities
Methods;
- Blood cultures
- Tissue/ prosthetic material sonication and culture
In managing a surface infection;
- What are 2 aims of treatment?
- What are 3 methods of treatment?
Aims;
- Sterilise tissue
- Reduce bioburden
Methods;
- Antibacterials
- Remove prosthetic material
- Surgery (Resect infected material)
What are 3 methods of prevention of surface infections on;
- Natural surfaces
- Prosthetic surfaces
Natural surface infection prevention;
- Maintain surface integrity
- Prevent bacterial surface colonisation
- Remove colonising bacteria
Prosthetic surface infection prevention;
- Prevent contamination
- Prevent bacterial surface colonisation
- Remove colonising bacteria
What are most UTIs caused by?
What are most pneumonia cases caused by?
What are most blood infections caused by?
UTIs: Urinary catheters
Pneumonia: Mechanical ventilation
Blood infections: Intravascular devices
What 2 types of bacteria are most commonly associated with hospital acquired
Staphylococci
Enterococci
