diseases and pathogens Flashcards
(48 cards)
what are the 4 Koch’s postulates?
- the microbe is found in all cases of disease but is absent from healthy individuals
- when the microbe is introduced to a healthy susceptible host the same disease occurs
- the microbe can be isolated from the diseased host and grown in pure culture
- the same strain of microbe is obtained from the newly diseased host
what do Koch’s postulates prove?
a host and a pathogen are needed to cause a disease
what are vaccines?
chemical agents that prime the adaptive immune system to repel a pathogen
what does it mean if someone is immune?
if they are exposed to the pathogen that they have been vaccinated against and don’t develop the disease
what are antibiotics and when are they used?
chemicals produced by bacteria and fungi that inhibit or kill other microbes
they are used when the patient already has an infection as the last resort
how are antibiotics divided into different classes?
each antibiotic in a class has the same structure with some small modifications that allow it to be taken differently by the patient (e.g. topical or oral) and used for different infections
what is a symptom?
a change in body function felt by the patient as a result of a disease e.g. tiredness
what is a sign?
a change in the body that can be measured or observed as a result of a disease e.g. temperature
what is a syndrome?
a specific group of signs and symptoms that accompany a disease e.g. cough, tiredness and temperature
what is the microbiota?
a population of bacteria that lives within all living multi-cellular organisms
they benefit our health through digestion, metabolism, immune function and mood
what are the 3 relationships between humans and microbes?
- commensalism: one organism benefits and the other is unaffected
- mutualism: both organisms benefit
- parasitism: one organism benefits at the expense of the other
what is C. difficile short for?
clostridium difficile
how does C. difficile grow?
its head contains a spore that allows it to survive harsh conditions and grow when conditions are favourable again
what disease is caused by C. difficile and what are the symptoms?
it causes clostridium difficile infection (CDI)
the symptoms are diarrhoea, colonisation of C. difficile bacteria, inflammation of the colon, abdominal pain and fever
why is C. difficile described as an opportunistic pathogen?
because it is a microbe that isn’t usually pathogenic but can cause infection or disease in a compromised host
it usually colonises the gut of patients in hospital who have received antibiotics that kills other species of bacteria in the gut
what disease does vibrio cholerae cause and what are the symptoms?
it causes cholera
the symptoms are diarrhoea, vomiting and abdominal pain caused by cholera toxin a cytotoxin that kills host cells
what do cholera patients usually die from?
they usually die from severe dehydration due to water loss from diarrhoea
what is the idea of epidemiology and who was it introduced by?
introduced by John Snow
it is the study of when and where diseases occur to control the spread of them
what are the 4 stages of epidemiology?
- identify patient zero (first person with the disease
- identify anyone who had contact with that person
- identify a reservoir for the pathogen
- block or contain the pathogen
what are epidemic diseases?
diseases acquired by many hosts in a given area at a short time
what are endemic diseases?
diseases constantly present in a population
what are pandemic diseases?
diseases that cause a worldwide epidemic
what is salmonella typhi and what symptoms does it cause?
a pathogen that causes typhoid fever
the symptoms include a rash, delirium, fever, pain, high blood pressure and diarrhoea
however the symptoms can be very variable
how is salmonella typhoid transmitted and treated?
human carriers (healthy individuals carrying the pathogen in their gall bladder)
spread by the faecal-oral route
treated by antibiotics and a vaccine
