Flashcards in Infection Prevention Deck (145):
How do many infections remain tranmissible?
Common non-human source
What is meant by a common non-human source?
A common source that a potential host comes into contact with, and acquires the infection
What can happen once a potential host has acquired the infection?
It can then be passed from person to person
What are the potential common non-human sources?
Give an example of a disease which has an environmental source?
What is legionnaires disease caused by?
Where can Legionella pneumophilia come from?
A common water source
How can a common water source spread Legionella pneumophilia?
The water source usually creates water droplets, and the bacteria is then spread via the droplet to a person
Give two examples of where a water source can create water droplets
Is Legionnaires considered transmissible between people?
Give an example of a pathogen that can be spread in food or drink
Where is E. coli o157 found?
In the GI tract of cows
What can E. coli o157 cause?
When can E. coli o157 cause gastrointestinal disease?
If it gets into meat/milk
How can E. coli o157 from meat/milk be transmitted between people?
Via faecal oral route
Give an example of a disease that can spread through animals
How does an animal act as a 'common source' for rabies?
It bites more than one person
What is meant by person-to-person direct transmission?
Spread from one person to another without intermediate, and this newly infected person can go on to infect someone else
Give three examples of disease spread person-to-person direct
How high does exposure to norovirus need to be to cause disease?
A very minimal exposure of 1 infectious particle is enough to cause infection in 50% of the population
What is meant by 1 infectious particle?
A clump of viruses bound by faeces, for example
Where does norovirus spread often occur?
In an enclosed environment
How is norovirus transmitted?
How is influenza transmitted from person to person
By droplet transmission
Can influenza be spread from to humans from animals?
How is Neisseria gonorrhoea spread?
Direct contact with another person
What happens in person-to-person indirect transmission?
Transmission occurs via a vector and cannot usually be transmitted onwards without one
Give three examples of diseases spread person-to-person indirect
How is malaria transmitted?
Via a mosquito that bites an infected individual, which then bites another individual
What happens when a mosquito bites an infected individual?
It picks up the plasmodium into their blood
How does the mosquito infect another person when it bites them?
It injects the infection into them via saliva
What can happen once a person has been infected with malaria?
The person can be bitten by another mosquito that can pass the disease on again
How is guinea worm transmitted?
A person with the worm washes their feet in water, allowing larvae to be hatched into it.
An aphid then eats the larvae and sits in the water
Ingestion of the aphid allows the larvae to evade digestion and survive in the GI tract, where it burrows to the feet to continue the cycle
How can schistosomiasis be transmitted?
What is meant by endemic disease?
The usual background rate of disease within a community with no extra factors to consider
What does the rate depend on in endemic disease?
The disease in question
What is an outbreak?
Two or more cases linked in time and place
What must be true for cases to be an outbreak?
The causative organisms must be of the same type
What is meant by an epidemic?
When a rate of infection is greater than the usual background rate
What is meant by pandemic?
A very high rate of infection spreading across many regions, countries, or contients
Give an example of a pandemic
Swine flu in 2009
What happened in the 2009 swine flu pandemic?
Originated in Mexico and spread throughout the world
What is the problem with pandemics?
They can cause large disruption to healthcare
What is how quickly an infection spreads affected by?
Its basic reproduction number (R0)
What is R0?
The average number of cases one case generates over the course of its infectious period, in an otherwise infected, non-immune population
What happens if R0 > 1?
The number of cases will increase
What happens if R0 = 1?
The number of cases will remain the same
What happens if R0 < 1?
Number of cases will decrease
When will an outbreak stop?
If everyone dies
Disease is overcome and immunity is developed
What diseases send to have a high R0?
Diseases spread by airborne route
Give two examples of diseases spread by airborne route with a high R0?
What is the R0 of measles?
What is the R0 of pertussis?
Give an example of a disease spread by the airborne route with a low R0
What is the R0 of influenza?
Can be as low as 2-3
What may the low R0 of influenza be a reflection of?
The development of personal immunity
What kind of diseases tend to have a low R0?
Diseases that are spread through sexual contact
Give an example of a disease spread by sexual contact that has a low R0
What is the R0 of HIV?
Why do diseases that spread by sexual contact have a low R0?
It is a contact that is less likely to occur
What do reasons for outbreaks, epidemics and pandemics relate to?
What pathogen factors can lead to outbreaks, epidemics, and pandemics?
The introduction of new pathogens or pathogenic features
What pathogenic features can be introduced that lead to outbreaks, epidemics, and pandemics?
New antigens on pathogens surface
New virulence factors
Give an example of a pathogen that often mutates its surface antigens
Give an example of a pathogen that may develop new virulence factors to cause outbreaks, epidemics and pandemics
Give an example of a pathogen that has antibiotic resistance
What patient factors can lead to outbreaks, epidemics, and pandemics?
Introduction of new hosts
In what form are non-immunes introduced into the communities all the time?
Babies that have not yet developed immunity
What is the result of non-immunes being introduced into the community?
There is more chance of the person becoming infected and spreading it to others
How can healthcare cause outbreaks, epidemics, and pandemics?
It can bring people into close contact with people that are infected, allowing a route for infection to spread throughout the population
What changes in human practice can cause outbreaks, epidemics, and pandemics?
Give an example of a social practice that can lead to outbreaks, epidemics, and pandemics
Increases in the number of body piercings have caused outbreaks due to unsanitary procedures
Give three examples of healthcare practices that can lea to outbreaks, epidemics, and pandemics
Central line usage
What is transmissibility affected by?
The infectious dose
What is the infectious dose?
The number of microorganisms required to cause infection
What can infectious dose vary depending on?
The type of microorganism
Presentation of microorganism
Immunity of potential host
What can the immunity of the potential host be affected by?
A large number of factors, including genetic disorders, infections like HIV, cancer, and different treatments
What is the infectious dose for cholera?
10^4 - 10^6 organisms
What is the infectious dose of E. Coli o157?
What trend to transmissions of infections often follow?
An epidemic curve
What does the epidemic curve of infection transmission show?
The progression of the majority of the population from susceptibility, to infection, and then to recovery
What nature of epidemic curve does small scale outbreaks?
Why do small scale infections show a stochastic epidemic curve
Due to the random nature of transmission of infection in small populations
How can infection be prevented?
Via intervention at a number of stages of the infection model
What interventions can be made at stages of the infection model to prevent infection?
Prevention of pathogens initial existence
Prevention of patient coming into contact with an existing pathogen
Prevention of development of patient/pathogen contact into infection
Prevention of further infection to other individuals
What can infection prevention be protein down into?
The 4 P's
What are the 4 P's?
Pathogen (and vectors)
How can infection be prevented when considering the pathogen?
Reduction/eradication of a pathogen Reduction/eradication of a vector
How can a pathogen be reduced or eradicated?
Effective use of antibacterial and disinfectants
What does the effective use of antibacterials and disinfectants allow for?
Decontamination and sterilisation of surfaces, equipment, and the environment
How can a vector be reduced or eradicated?
Eliminating breeding sites
Killing or controlling existing vectors
What vector can be reduced/eradicated by eliminating breeding sites?
What vector can be reduced/eradicated by killing or controlling existing vectors?
How can infection be prevented when considering the patient?
How can health be improved in the patient to prevent infection?
Nutrition and medical treatment
What kinds of immunity can be conveyed to the patient to prevent infection?
How can passive immunity be conferred to patients?
How can active immunity be conveyed to the patient to prevent infection?
How can herd immunity be used?
By vaccinating a proportion of the population to reduce the amount of potential people that can cause secondary transmission and thus protecting unvaccinated people by decreasing their likelihood of coming into contact with someone with an infection
What does the proportion of the population that needs to be vaccinated for herd immunity to work vary with?
The R0 of the infection
How can infection be prevented when considering practice?
Avoidance of pathogen or its vector
In what ways can the pathogen or vector be avoided?
Protective clothing or equipment
What protective clothing or equipment can be used to prevent infection?
Long sleeves/trousers against mosquito bites
PPE in hospitals
What PPE is used in hospitals?
What behavioural practices can be used to prevent infection?
Safe disposal of sharps
Food and drink preperation
How can infection be prevented when looking at the place?
How can environmental engineering prevent infection?
Good quality housing
Well designed healthcare facilities
How can surveillance be used to prevent infection?
Monitor what is happening now
What could happen in the future
What are the consequences of good infection control?
Decreased incidence of disease/organism
What diseases have decreased incidence due to good infection prevention?
What is the consequence of bad infection control?
Decreased exposure to pathogen
Later average age of exposure
What does decreased exposure to pathogen lead to?
Decreased immune stimulus
What is the result of a decreased immune stimulus?
What is the result of decreased immune antibodies?
Increased susceptible people
What is the result of increased susceptible people
What is the result of a later age of exposure to infection?
What diseases have an increased severity at a later age of exposure?
What does all exposure of bacteria to antimicrobials lead to?
A level of antimicrobial resistance
Is antimicrobial resistance reversible?
What is the problem with new antimicrobial development?
It is stalled- no new antibiotic classes since 1987
What are the consequences of antimicrobial resistance?
How much does antibiotic resistance cost in the EU?
Approx €1.5billion a year
How many deaths per year are there in the EU from antimicrobial resistance?
How many deaths per year due to antimicrobial resistance are there per year in Thailand?
What does the acronym MDR mean?
What is meant by multi-drug resistance?
Non-susceptibility to one agent in three or more antimicrobial categories
What does the acronym XDR mean?
Extensively drug resistant
What is meant by extensively drug resistant?
Non-susceptibility to at least one agent but two or fewer antimicrobial categories
What does PDR mean?
Non-susceptibility to all agents in all antimicrobial categories
What does antibacterial use lead to?
How can the fact that antibacterial use leads to resistance be backed up?
Individual level data
What is the purpose of lab evidence when determining the link between antibacterial use and resistance?
Provides biological plausibility
What is the purpose of ecological studies when determining the link between antibacterial use and resistance?
Relates levels of antibacterial use in a population with level of resistance
What is the purpose of individual level data when determining the link between antibiotic use and resistance?
Relates prior antibacterial use in an individual with the subsequent presence of bacterial resistance
What does an antimicrobial stewardship programme consist of?
Multidisciplinary team and relationships to other quality/safety teams
Who does the multidisciplinary team involved with antimicrobial stewardship consist of?
Medical microbiologists/infectious diseases physicians
Infection control nurse
Information system specialist
What does the multidisciplinary team involved in antimicrobial stewardship link in with?
Infection prevention and environmental decomination
What happens in surveillance in antimicrobial stewardship?
What process measures are taken in antimicrobial stewardship?
Over time in same institution
Benchmarking against other institutions
What measures are taken of antibacterial use in antimicrobial stewardship programmes?
Give an example of how quantity of antibacterial use can be measured in antimicrobial stewardship
Defined daily doses / 1000 bed days
What is meant by appropriateness of antibacterial use in antimicrobial stewardship?
Adherence to guidelines
What outcome measures are taken in antimicrobial stewardship?
Emergence of resistance
C. Difficile infection rate
What does antimicrobial stewardship aim to do?
Ensure appropriate use of antimicrobials
Create optimal clinical outcomes
Minimise toxicity and other adverse events
Reduce costs of health care from infections
Limit the selection for antimicrobial resistant strains