Microbes and disease Flashcards
How is it possible to find the microorganism that caused a disease
Pathogenic organism should be in all disease cases and no healthy ones
Isolate suspected microorganism, grow in pure lab culture
When host inoculated with the pure microorganism culture should produce disease in the healthy animal
Organism should be reisolated and shown to be same as original
What was Robert Koch’s findings
His findings on tuberculosis
Described criteria needed to prove specific microbe caused disease
What was Walter Reed’s findings
Yellow fever transmitted by mosquitoes
NOT direct contact
What was Alexander Fleming’s findings
Mould penicillium notatum kills staphylococcus aureus bacterium
What was Gerhard Domgak’s findings
Synthesises protonsil, used to killed streptococcus
What was Waksman et al. findings
Streptomycin for TB treatment
What was Jenner’s findings
Smallpox eliminated using by inoculating with cowpox
What was Stanley Prusiner’s findings
Describes infectious proteins - prions cause scrapie in sheep
What was Luc Montaigner and Robert Gallo’s findings
Virus they found (HIV) causes AIDS
What was Barry Marshall’s findings
Demonstrates that isolates from patients with ulcers all have helicobacter pylori
What was Craig Venter et al.’s findings
First complete sequence of haemophilus influenza
What were the significant milestones in the impact of genetics
Complete DNA sequence of all eukaryote chromosomes (S.cerevisae) determined
Complete eubacteria, archaea, viral genomes
Prokaryotic, viral genomes, eukaryotic genomes sequenced
What were Koch’s postulates
Gene found associated with pathogen
Mutation of that gene attenuates virulence of a pathogen
Transfer of gene can give other organisms disease
An example of an opportunistic pathogen
Listeria monocytogenes
An example of an obligate pathogen
Chlamydia trachomatis
Types of epidemiology
Sporadic - individual cases, unknown sources
Family outbreak - home prepared foods
General outbreak - distributed foods
What causes infections
Bacteria
Viruses
Protozoa
Helminths
What causes intoxications
Bacteria
Fungi
What are exotoxins and what do they do
Extracellular diffusible toxins
Normally proteins secreted during exponential growth
What causes food poisoning
Ingesting toxins in food
Interfere with biochemical processes
What causes a food-borne infection
Ingestion and growth of pathogenic microbes - mainly caused by improper storage or cooking
Examples of naturally produced toxins
Rhubarb leaves
Kernels of soft fruit
What are examples of bacterial toxins
Bacillus cereus
Clostridium botulinum
Clostridium perfringens
Staphylococcus aureus
What are examples of bacterial infection
Campylobacter
Listeria
Where can bacillus cereus be found
Spores are heat resistant and germinate in cooled food after cooking
Cereals and rice survives in reheated foods
Where can clostridium botulinum be found
Associated with meat or canned foods not reheated before eating
Heat sensitive but germinates in cooled food
Where can clostridium perfringens be found
Natural part of animal gut microflora
Spore found in faeces
Associated with cooked meat products
Where can staphylococcus aureus be found
Natural part og skin/nasopharynx microflora
Associated with salad bars and prepared foods
Where can campylobacter be found
Mainly from poultry or other raw meat
Natural habitat is bird intestine
Where can listeria be found
Normal habitat is mammal intestine, soil and plants
Can grow in refrigeration temperatures
Many sources e.g. dairy, salad, cold meat
