GI Infections Pathogens Flashcards
What is normal flora
beneficial/good bacteria ]not all colonisation is normal
begins at birth
What traits increase an invading organisms chance of success
High growth rates
Dispersal capability
Phenotype plasticity
Genetic diversity
Stages of invasion
Introduction -to a new environment/community
establishment-and maintenance of a viable invader
growth and spread-upon the acquisition of resources
impact - of varying consequences
Where are new pathogens colonised
In the tissue under the epithelial cells
What does colonisation mean
The establishment of a microorganism within or on a host - may be short lived
What is a pathogen
Any microorganism the potential to cause disease
What happens in the incubation period
Pathogen replicates in host
What immune system components target bacteria
Phagocytes
Antibodys and B lymphocytes
Complement proteins
What immune system components target viruses
T lymphocytes
antibodies and B lymphocytes
What immune system components target fungus
Eosinophils
T lymphocytes
Phagocytes
What immune system components target protozoa
T lymphocytes
Eosinophils
What immune system components target worms
Eosinophils
Mast cells
What colour to gram +ve bacteria stain and why
PURPLE
peptidoglycan wall traps crystal violet dye
What colour do gram -ve cells stain and why
PINK
no peptidoglycan wall to trap crystal violet dye so it is easily washed away
What are enterobacteriaceaec
Gram negative rods
Non spore forming
Ferment sugars
How do enterobacteriaceae cause disease
Motility - flagella (lash like appendage) allows movement
Fimbriae help colonisation by binding tight to tissue
Endotoxin
What two enterobacteriaceae non-mobile
shigella and klebsiella
What is MALDI-TOFF mass spectrometry
Analyses protein component of bacteria cell wall
Compares with a data base
Differentiates between highly similar organisms
Can tell if a bacteria is pathogenic or non pathogenic
Steps to identify enterobacteriaceae
Collect appropriate clinical sample
Perform gram stain
Lab selects appropriate biochem tests
report results to clinicians
What is the normal flora in the mouth
Strep “virdans”
Neisseria sp
Anaerobes candida sp
Staphylococi
What is the normal flora of the stomach/duodenum
Low pH
Usually sterile
Few candida and staphylococci may survive
Normal flora of the jejunum
small numbers of coliformas and anaerobes
Normal flora of the colon “faecal flora”
Large numbers of coliforms, anaerobes and enterococcus faecalis
Normal flora of the bile ducts
Sterile
Anaerobes of the GI tract
Strict anaerobes- will not grow in presence of oxygen
Clostridium
Bacteroides
Anaerobic cocci
present in large numbers in the large bowel
