Infection Session 8 Flashcards
Can a vector be inanimate?
Yes
What are the three communicable natures of infections?
Common source
Person-to-person direct
Person-to-person indirect
Give some examples of common source infections.
Legionella pneumophilia
Food poisoning
Rabies
Give some examples of person-to-person direct communicable infection causative agents
Influenza
Norovirus
Neisseria gonorrhoea
What are the consequences of transmission of infection?
Endemic disease
Outbreak
Epidemic
Pandemic
What is endemic disease?
Usual background rate of a disease
What is the definition of an outbreak in infection?
> /= 2 cases linked in time and place
What is the definition of an epidemic?
Rate of infection > usual background rate (strictly defined for some infections)
What is the definition of a pandemic?
V. high rate of infection spreading across many regions, countries and continents
What is basic reproduction number?
The average number of cases one case of infection generates over the course of its infectious period in an otherwise uninflected, non immune population
What is seen when basic reproduction number (R0) is >1?
Increase in cases –> ourtbreak
How does the R0 of measles compare to that of influenza?
Much higher
What pathogen factors can cause outbreaks, epidemics and pandemics?
Antigenic drift
Antigenic shift
Toxin production –> environmental contamination
What patient factors can contribute to outbreaks, epidemics and pandemics?
New hosts
Immunosuppressed population
Healthcare
What practice factors can contribute to outbreaks, epidemics and pandemics?
Social practice e.g. Sexual behaviour, drug use
Healthcare practice e.g. High bed occupancy
What place factors can contribute to outbreaks, epidemics and pandemics?
Migration introducing new pathogens of native infection to unexposed populations
What factor determining transmissibility varies by microorganism, it’s presentation and immunity of potential host?
Infectious dose
Give some examples of high and low infectious dose microorganisms.
High: salmonella, cholera, bacillus anthracis
Low: C. Parvum, E.coli
What does small scale outbreaks being stochastic in nature mean?
Cases show random distribution leading to a normal epidemic curve shape which can alter position
What is the implication of small scale outbreaks being stochastic in nature?
Interventions can only be proven to work if they are effective in more than one outbreak
What non-biological factor might cause an increase in the number of lab reports of an infection?
Change in ascertainment (how infection is reported)
What three stages cause the normal shape of an epidemic curve?
Susceptible (lots of secondary cases) –> infected –> recovered/increased immunity/death
What patient interventions can be used to prevent infection?
Improve health of population
Passive immunity
Active immunity
Herd immunity
What does the proportion of people needed to vaccinate for effective herd immunity depend on?
R0 (higher it is, greater % need vaccinating)
What practice interventions can be used to prevent infection?
Avoid pathogen/vector geographically, PPE and behaviourally (safe sex, safe disposal of sharps, food and drink prep)
What place interventions can be used to prevent infection?
Environmental engineering to provide safe water and air
Good quality housing
Well designed care facilities
What aids local infection control to reduce risk?
Surveillance to monitor local, global and future trends
What are the consequences of good infection control?
Decreased incidence or elimination of disease
What are the consequences of poor infection control?
Decreased exposure to pathogen –> decreased immune stimulus –> lack antibodies –> increased number of susceptibles –> outbreak
Later average age of exposure due to decreased environmental levels leads to greater severity of disease experienced
Why is Abx resistance almost as old as the Abx themselves?
Produced naturally by bacteria and moulds for evolutionary advantage
What is the implication of carbapenem-resistant enterobacteriaceae?
It has genes which code for carbapenamase which also confer resistance to other Abx therefore the last resort Tx for G-ve bacteria is ineffective
Is it just inappropriate prescribing of Abx that causes antimicrobial resistance?
No, any exposure of bacteria to antimicrobials can
What is the implication for using empirical Abx therapy in antimicrobial resistance?
Much more likely to get empirical Abx estimate wrong and hence increase mortality
What is the definition of a multi-drug resistant (MDR) microbe?
Non-susceptibility to =/>1 agent in =/>3 antimicrobial categories
What is the definition of an extensively drug resistant (XDR) microbe?
Non-susceptibility to at least 1 agent in all but 2 or fewer antimicrobial categories
What is the definition of a pan-drug resistant (PDR) microbe?
Non-susceptible to all agents in an antimicrobial category
What does laboratory evidence provide to indicate antibacterials causes resistance?
Biological plausibility
What evidence do ecological studies provide to indicate antibacterials cause resistance?
Overall high levels of antibacterial use lead to more resistance
What individual level data provides evidence that antibacterials cause resistance?
Abx prescribed in UTI –> increased rates of carriage of resistant bacteria in recipients –> longer durations and multiple courses –> increased resistance rates
What is the smallest change necessary to give rise to antimicrobial resistance in a bacteria?
Single nucleotide
Can legionella pneumophilia cause inward transmission after infecting a human host from the environment?
No
What are the 5 objectives of antimicrobial stewardship?
Appropriate use of antimicrobials Optimal clinical outcomes Minimise toxicity and adverse events Decrease costs of healthcare for infections Limit selection for microbial strains
How are the 5 objectives of antimicrobial stewardship achieved?
Use of an MDT
Surveillance of process
Surveillance of outcome
Measures of interventions
Give some examples of persuasive interventions in antimicrobial stewardship.
Education Consensus of best practice Opinion leaders Reminders Audit feedback
Give some examples of restrictive intervention in antimicrobial stewardship.
Restricted susceptibility reporting
Formulary restriction
Validation codes
Automatic stop orders
Give some examples of structural interventions in antimicrobial stewardship.
Computerised records
Rapid lab tests
Quality monitoring
Which type of intervention in antimicrobial stewardship is slower to take effect but long-term is as effective as restrictive interventions?
Persuasive
What process measures can be used in antimicrobial stewardship?
Look at trends in antibacterial use and consider defined daily doses per 1000 bed days, classes and appropriateness over time +/- other institutions
What outcome measures can be used in antimicrobial stewardship?
Pt outcomes
Emergence of resistance
C.diff infection rate
What is needed for successful antimicrobial stewardship?
Long term confirmed and appropriate resources supported by leadership w/delegated leadership for challenge integrated into organised pt safety and QoL care
Give an example of an effective antimicrobial stewardship case.
Cephalosporins control on CDI in Leicester:
Introduced restoration codes first (quantitative restriction) followed by physical removal of cephalosporins from wards (qualitative restriction) –> marked decrease in total C.diff cases
