Prescribing in Infection Flashcards
what is AMR
- This is the ability of a microorganism to resist the action of one or more antimicrobial agents
What are the key drivers in the development of antimicrobial resistance
- indiscriminate or inappropriate use of antimicrobials
- patients not taking prescribed antimicrobials as directed
- poor hygiene practices in healthcare settings
- poor personal hygiene practises
- lack of new antimicrobials being developed
How do you define antimicrobial stewardship
- An organisation or healthcare system wide approach to promoting and monitoring judicious use of antimicrobials to preserve their future effectiveness
What is the aim of antimicrobial prescribing and stewardship
- improve the safety and quality of patient care
- reduce the risks of inadequate, inappropriate and ill effects of treatment
- contribute to the reduction in emergence and spread of antimicrobial resistance
What are the 5 domains to be considered in antimicrobial prescribing
- infection prevention and control
- antimicrobial resistance and antimicrobials
- prescribing antimicrobials
- Antimicrobial stewardship
- monitoring and learning
What is Start Smart - Then Focus
- this is a toolkit developed by pubic health England to reduce inappropriate prescribing and optimise the use of antimicrobials in hospitals
What happens in start SMART
- obtain cultures prior to starting treatment where appropriate
- take a drug allergy history
- start antimicrobials within one hour of recognition of red flag sepsis, septic shock or life threatening infections
- comply with local antimicrobial prescribing guidelines
- document the indication for treatment, severity of the infection, dose, route, and frequency on both the prescription an din the medical notes
- state a review or stop date
- consult the microbiologists and/or antimicrobial pharmacist for advice where appropriate
What happens in Then FOCUS
At 48-72 hours review the patient and make (and document) the management plan, including the next review or stop date
- stop treatment (e.g. if there is no evidence of infection)
- switch from intravenous to oral treatment
- change the antimicrobial
- continue the current treatment plan
- refer for outpatient parenteral antibiotic therapy (OPAT)
What organisms appear negative on the gram stain
- Gram negative organisms such as Escherichia coli
Why are gram negative organisms negative on the gram stain
- have a thiner cell wall that can be de stained
What are gram positive organisms positive on the gram stain
- these have a thick cell wall that retains the gram stain and renders them positive
describe the differences and similarities in terms of the wall on the gram positive and gram negative organisms
Similarities
- cell membrane consisting of a phospholipid bilayer
- layer of peptidoglycan on the outside
Differences
- gram negative has a thin peptidoglycan layer and a second membrane
- Gram positive - lacks the 2nd membrane but has a much thicker peptidoglycan layer
vancomycin has…
no activity against gram negative
ciprofloxacin …
has poor gram positive activity
What is a cell wall
- rigid structure which maintains the cell shape and high osmotic pressure inside the organism
What does disruption to the cell wall result in
- disruption of the cell wall leads to lysis of the cell and subsequent death of the organism
What antibacterials inhibit cell wall formation and result in cell death
beta lactam antibacterials - such as penicillins, cephalosporins, and carbapenems
- Glycopetpide antibacterials such as vancomycin and teicoplanin inhibit a different stage of cell wall formation nd when given in high concentration can cause death
What bacteriostatic antibacterials inhibit protein synthesis
- Macrolides (such as clarithromycin) and tetracyclines ( such as doxycycline) are bacteriostatic agent’s
- they inhibit protein synthesis but do not kill the cell but do stop it from growing
What bactericidal antibacterials inhibit protein synthesis
- Aminoglycosides such as gentamicin are bactericidal agents
- these inhibit a vital cellular process which leads to cell death
What do quinolone do
They interfere with DNA synthesis
what antibacterial is only active against anaerobic bacteria
- Metronidazole
What does trimethoprim do
- interferes with bacterial folate metabolism and results in a lack of purine analogues for DNA synthesis
What does Daptomycin do
- binds to bacterial membranes, leads to depolarisation of the membrane, causes rapid inhibition of protein, DNA and RNA synthesis and therefore cell death
What are defensive strategies that bacterial have developed against antibacterials
- Efflux pumps = can pump any antibacterial which has passed through the outer membrane back out before they reach the target site
- Antibacterial modifying enzymes = destroy the antibacterial before it reaches its target within the cells
- Mutations - in the target site of antibacterial prevent it binding
What factors do you consider when prescribing an antimicrobial
- national/local antimicrobial prescribing guidelines
- spectrum of antimicrobial activity
- site of infection
- cultures and sensitivities
- patient factors
- route of administration
- duration of treatment/intended review date
What are factors that can influence antimicrobial prescribing decisions
- patient expectations
- prescriber fear that they may miss a significant bacterial infection leading to patient deterioration
- difficulty distinguishing between a viral and bacterial infection
- day of the week
- pressure from colleagues
- influences of colleagues prescribing practise
why should you follow local guidelines for prescribing antibacterials
- Local guidelines will have taken into account local resistance pattern
- based on evidence, national guides and represent the preferred choice of the turst
- limit the inappropraite use of broad spectrum agents helping to prevent resistance development and secondary infections due to resistant organisms
- local guidelines will recommend the use of agetns that are available in the hospital
- promote the use of cost effecitve agents
How do you treat infection when a person first arises with an infection
- Broad spectum anitbitoic which covers all of the most common causative organisms
What can broad spectrum anitbotics result in
Multi drug resistant strains and clostridioides difficile
What should you clearly document in antibiotics
- indication for antibacterials in the notes and on the drug chart
- intended route and duration
What infection is Co-Amoxiclav associated with
C.difficile infection
How can you calculate renal function
Cockcroft-Gault equation
creatine clearance = Fx(140-age(years)) x weight (kg) / serum creatine (micromol/litre)
F = 1.04 in women F = 1.23 in men
when must IV antimicrobials be prescribed within 1 hour
- In the management of sepsis IV antimicrobials have to be administered and prescribied within 1 hour of diagnosis
what happens if you have uneven distribution of dosing
- this leads to supra-therapeutic concentrations, this increases the risk of toxic effects or subtherapeutic causing the concentration to fall below the one deemed effective
When are IV antibiotics required
- if there is a systemic infection
- when patient cannot tolerate oral route
what should you also consider when administring the drug and the route you administer the drug to
- does it have good oral bioavailability
What is bioavailability
- extent to which a drug reaches the systemic circulation where is is avaliable to act as the effector site
When does a drug have a bioavailability of 100%
when it is administered IV
When can the IV to oral switch be made
- can be made 24-48 hours of treatment in most infections
What conditions can need long lasting IV antibitoics
- infective endocarditis
- osteomyelitis
What can happen when antibiotics are given for longer than required
- nasuea
- antibiotic associated diarrhoea
- development of clostridioides difficile infection
In order to de-escalate therapy what 5 presribing decisions should be made 48 hours after initiating IV antibiotics
- stop the antibacterials
- swtich IV therapy to oral route
- change the antibacterial
- continue and review again in 72 hours
- refer for outpatient parenteral therapy
what can patients have that do not require antibacterials
- acute cough
- acute otitis media
- acute sinusitis
- acute sore throat
What are the self care counselling points for all self limiting infections
- drinking plenty of fluids
- simple analgesia as appropriate
- rest
urine dipstick tests are an …
unreliable diagnostic method for catheter related UTIs - urinary catheters quickly become colonised with bacteria and the dipstick will only detect their presence
How should you treat someone who has an UTI from a catheter
- antibacterials should be prescribed
- urinary catheter should be removed in possible
- urine sample can then be collected as this remains a focus of infection
Name an antibacterial drug that must be avoided with alcohol
Metronidazole - and for 48 hours after completing the course
- infection causes a disulfiram like reaction occuring causing flushing, shortness of breath and a throbbing headache
what do super resistant organisms produce
- carbapenemases
Why are some antibacterials restricted agents
- they are broad spectrum agents - where inappropriate use would promote development of resistance
- need to be resereved for serious infections where multi-drug resistant organisms are known to be present or suspected
- may be potentially toxic and use may be limited in duration or they require specialist monitoring
- may be expensive and inappropriate use may waste limited resources
