Session 6-Infections On Surfaces Flashcards
What is a surface?
Interface between solid and either liquid or gas
Which skin surfaces can infection arise from?
Epithelium
Hair
Nails
Which mucosal surfaces can infection arise from?
Conjunctival
Gastrointestinal
Respiratory
Genitourinary
Which viruses are skin microorganisms?
Papilloma
Herpes simplex
Which gram positive bacteria are present on skin?
- Staphylococcus aureus
- Coagulase negative staphylococci
- Corynebacterium
Which gram negative bacteria are present on skin?
Enterobacteriaceae
Which fungi are present on skin?
- yeasts
- dermatophytes
Give an example of flora in the eye
Coagulase negative staphylococci
Give an example of flora in the nasopharynx
Neisseria meningitidis
Streptococcus pneumoniae
Give an example of flora in the mouth
Viridans streptococci
Give an example of flora in the stomach
Helicobacter
How do people get infections and give an example of an infection for each method?
- invasion: strep pyogenes pharyngitis
- migration: E. coli UTI
- inoculation: coagulase negative staph prosthetic joint infection
- haematogenous: viridans Strep endocarditis
Give examples of external surface infections
Cellulitis Pharyngitis Conjunctivitis Gastroenteritis UTI Pneumonia
Give examples of internal surface infections
Endocarditis Vasculitis Septic arthritis Osteomyelitis Empyema
Which organisms cause prosthetic joint infections?
- Coagulase negative staphylococci
- Staphylococcus aureus
Which organisms cause cardiac pacing wire endocarditis?
- coagulase negative staphylococci
- staphylococcus aureus
What are the processes in the pathogenesis of infection at surfaces?
- adherence to host cells or prosthetic surface
- biofilm formation
- invasion and multiplication
- host response (pyogenic or granulomatous)
What is biofilm?
Slime layer which protects bacteria against host defences and antimicrobial agents
What are the three principles of quorum sensing?
1) signalling molecules - autoinducers (AI)
2) Cell surface or cytoplasmic receptors
3) gene expression -> co-operative behaviours and more AI production
How can natural surface infections be prevented?
- maintain surface integrity
- prevent bacterial surface colonisation
- remove colonising bacteria
How can prosthetic surface infections be prevented?
- prevent contamination
- inhibit surface colonisation
- remove colonising bacteria
