6.1 Surface Infection Flashcards
Define surface
Interface between a solid and liquid/gas
Skin micro-organisms
Viruses: Papilloma, Herpes simplex
Bacteria: (+ve) Corynebacterium
(-ve) Enterobacteriaceae
Fungi: Dermatophytes
Parasites: Mites
Examples of Where and What Normal flora can be found?
Eye - coagulase negative staphylococci
Nares- Staph. aureus
Nasopharynx- Streptococcus pneumoniae
Mouth- Neisseria
Stomach- Streptococci
Intestine- Bacteroides
Urethra- Enterobacteriaceae
Vagina- Lactobacili
Mechanism of infection
Invasion
Migration
Innoculation
Haematogenous
Examples of External and Internal natural surface infections
External: Cellulitis, Pharyngitis, UTI
Internal: Endocarditis, Vasculitis, Septic arthritis
Examples of prosthetic surface infections
Cardiac valves
Pacing wires
What organisms cause Prosthetic valve endocarditis
Native, prosthetic valve endocarditis >1 yr post-operation: Streptococci, Enterococcus
Prosthetic valve endocarditis <1yr post-operation:
Coagulase negative staphylococci
Causative organisms of Prosthetic joint infection
Coagulase negative staphylopcocci
Staphlyococcus aureus
Causative organisms of Cardiac pacing wire endocarditis
Coagulase negative staphylococci
Staphylococcus aureus
Process of pathogenesis of infection at surfaces
- Adherence to host cells/prosthetic surface
- Biofilm formation
- Invasion and multiplication
- Host response (pyogenic, granulomatous)
Explain Quorum sensing and its three principles
Modulation of gene expression in response to changes in cell population density
As the population increases, autoinducers increases. These AI can control various behaviours
-Signalling molecule; autoinducers (controls biofilms)
-Cell surface receptors
-Gene expression
What does Quorum sensing control
-Sporulation (formation of highly resistant structures to withstand extreme conditions)
-Biofilm formation
-Virulence factor secretion
