Session 6 Flashcards
(36 cards)
What viruses are on the skin?
Papilloma
Herpes simplex
What gram positive and gram negative arterial live on the skin?
Positive
- Staph aureus
- Coagulase negative staphylococci
Negative
- Enterobacteriacae
What fungi and parasites are present on the skin?
Fungi
- yeast
- dermatophytes (cause athletes foot)
Parasites
- mites
What is the role of lactobacilli in the vagina?
Lactic acid helps keep it acidic = helps prevent overgrowth of candida = thrush
Also found in other regions that require an acidic environment e.g stomach, urethral mouth, etc.
How do people get infections?
- invasion
- migration e.g. E. coli UTI
- inoculation
- haematogenous
What is endocarditis?
Inflammation of the endocardium. Turbulent blood flow can erode the surface of the heart valves = exposed.
Bacteria will then latch on and there will be an immune response
Why is endocarditis associated with poor oral hygiene?
Bacteria can get into the blood stream through bleeding gums
What is a large head in children a sign of?
Blocked ventricles = increased venous pressure
What bacteria is likely to cause prosthetic valve endocarditis >1 post op?
Viridans streptococci Enterococcus faecalis Staph aureus HÁČEK group Candida
What bacteria is likely to cause prosthetic valve endocarditis after a year post op?
Coagulase negative staphylococci
What is prosthetic valve endocarditis?
Endocarditis you’re at risk of when you have a valve replacement
What bacteria cause prosthetic joints?
- coagulase negative staph
- staphylococcus aureus
What bacteria cause cardiac pacing wire endocarditis?
- coagulase negative staph
- staph aureus
What is the process in the pathogenesis of infection at surfaces?
1) Adherence to host cells/ prosthetic surface
2) biofilm formation
3) invasion and multiplication
4) host response
- pyrogenic = neutrophils = pus
- granulomatous
How do microorganism cause disease?
Virulence factors
- exotoxins e.g cytolytic
- endotoxins
Host cell damage
- direct
- consequent to host immune response
What are the challenges in identifying a infecting organism?
- adherent organisms = stick well to surfaces = difficult to get sample
- low metabolic state/small colony variants
What are Biofilms?
Microbial communities attached to surfaces and encased in an extracellular matrix of microbial origin.
On pathogens and helps them survive so therefore cause disease in humans
What two bacteria are responsible for the majority of hospital acquired infections?
Staphylococci
Enterococci
What are the two classifications of. Staphylococci?
1) coagulase positive e.g staph aureus
2) coagulase negative e.g staph epidermidis
How do biofilms form?
1) surface attachment of free floating bacteria onto a conditioning film
2) micro-colonies grow by cell proliferation and coaggregation
3) Marco colonies (mushroom and tower like structures) and cell detachment occurs
Why does a biofilm make it difficult for antibiotics to kill the bacteria?
The matrix acts to restrict the penetration and diffusion of some antimicrobials
Biofilm can also secrete B lactamases into environment to increase expression of multi drug resistance efflux pumps.
What is quorum sensing?
Bacteria produce and release chemical signalling molecules called autoinducers that increase cell density = more biofilm = harder to antibiotics to kill bacteria.
What are the management options for infections and what are the challenges?
Management
- antibacterials
- remove prosthetic material
- surgery to resect infected material
Challenges
- poor antibacterial penetration to biofilm
- low metabolic activity of biofilm micro organism
- dangers/difficulties of surgery
What type of bacteria are streptococci?
Gram positive cocci
