Antibiotics in practice Flashcards
How are we increasing resistance?
*Doctors and vets - over prescribe antibiotics
*Patient does not comply to advice on administration
*Poor hygiene/lack of infection prevention and control
*People/animals travelling around the world, spreading resistant bacteria
How do bacteria become resistant?
*turn on certain internal resistance processes
*change to protect themselves from an antibiotic
*receive resistant genes from other bacteria.
Describe AMR?
Antimicrobial resistance threatens the effective prevention and tx of an ever-increasing range of infections caused by: bact, parasites, viruses & fungi
Describe AR -> Antibiotic Resistance
Compromise the success of major surgery, cancer chemotherapy, organ transplants & diabetes management become very high risk
Describe antimicrobial/ biotic stewardship?
- Measures that can help mitigatea a public health crisis and preserve the effecitveness of available AM agents
What is the 3 R framework of continuous improvement ?
Reducing, Replacing, refining (use of AM agents)
What are some potential ‘solutions’ for AMR ressitance?
- Research - improved detection and diagnosis of infections.
- Refined dosing regimens- simultaneously effective while not selecting resistance.
- Finding alternatives to antimicrobial agents.
- Development of improved vaccines to enhance immunity and reduce disease
What si the 7 pt plan from BVa?
Detail the ‘protect me’ acronym?
Describe Empirical Therapy?
*organism unknown - cover likely pathogens
*site of infection and assume most likely organism and susceptibility
e.g. skin infections-Staphylococcus spp., most UTIs- Escherichia Coli
……Consider need / feasibility of culture & sensitivity follow up. Gram stain if possible
Describe Definitive Am Therapy
*Infective organism is known (culture & sensitivity tested)
*Narrow-spectrum antibiotics preferred over broad-spectrum
……The more at risk a patient is for AMR to be present, the more important C&S becomes
Describe Prophylactic AM therapy?
*Used in healthy individuals to prevent infection
e.g. surgery taking >90 minutes or where an implant has been inserted.
………No need in sterile routine surgery- being brave!!!….trusting your skills!!!!
how should we consider Location & severity of infeciton in AM chocie?
- Bacteria at the infection site - concentration of AB at site
- Perfusion limitations
- Permeability limitations - drug distribution to the CNS, eye, epithelum EXCEPTION - meningitis
- Location of the bact/ microrg -> intracellular pathogens less susceptible
Give some examples of intracellular pathogens?
Salmonella, Brucella, Toxoplasma, Listeria, Mycobacterium
What host factors to consider?
- Immunocompetent patient -> bacteriostatic ABs may be sufficient!
- Immunocompromised -> bactericidl for cure
- Paediatric/ geriatric -> body size/ organ dev/ dysfunction
- Recent AB therapy without a cute -> current infection under selective pressure of another AM agent and can eb resistant
What LOCAL factors?
- The larger the bacterial inoculum at the infection site, the greater the concentration of AB needd
- Surface biofilms - Form in FBs or natural surfaces and dec the effectiveness of ABs
- AB efficacy signifcantly reduced in pus, necrotic or oesdematous tissue
Client factors?
❑ Dosing schedule - correct antibiotic concentrations in infected tissue
❑ Completing therapy duration - Premature cessation- lead to relapse/
contribute to AMR
❑ Cost factors – both medicine cost and sensitivity testing - willingness
to pay for optimal treatment? – better client education ?
❑ Inappropriate storage of medicine may affect pharmaceutical quality.
❑ Inappropriate route – client unable to tablet their cat
What to consider with Efficacy & pharmacokinetics?
❑ MIC – minimum inhibitory concentration / kill organism
❑ Remain below the level toxic to the patient –‘sensitive’ vs ‘resistant’
❑ Insufficient dose - AMR - aim for IC80-IC90 at infection site
❑ Concentration-dependent; fluoroquinolones, aminoglycosides
❑ Time-dependent; beta-lactams
❑ Synergistic effects - appropriate combinations - resistant infection
render susceptible
What safety considerations?
❑ Antibiotic targets - specific to prokaryotic cells, tend to be safe.
❑ Host toxicity – different mechanism to antimicrobial mechanisms
–e.g. aminoglycoside toxicity due to accumulation in renal tubules
❑ Paediatric/ geriatric patients - susceptible to drug toxicity
❑ Impaired renal or hepatic function- increased risk
❑ Pregnancy- increase sensitivity to antibiotics (mother, foetus)
❑ Lactating females- transfer antibiotics to nursing neonates
❑ Hypersensitivity reactions- less in veterinary patients than humans.
How to dose accurately?
take weight
-> Inc dose for:
- serious or chronic infections
- tissues difficult to penetrate
- infections ass with detrimental changes at - site of infection
Conc vs Time dependent?
- Concentration-dependent antibiotics- high dose once a day
- Time-dependent antibiotics- frequently administered to maintain drug concentration at
the site of infection above the MIC (e.g. beta-lactams)
What duration considerations?
- Longer not always better
- Shorter / stopping prematurely can have lower cost & less toxicity BUT potential AMR, reoccuring infection, spread to others & inc need to hospitalise
How should we choose durations then?
- Uncomplicated acute infections 5-7 days (or less);
- Response seen in 2-3 days if treatment.
- Revaluate diagnosis/treatment if response is inadequate
- Best to continue 2 to 3 days beyond resolution of clinical signs.
- Chronic infections - 4–6 weeks or more with susceptibility testing and re evaluation
