Antimicrobials Flashcards
What is the goal of antibacterial therapy?
Help the body eliminate infectious organisms without toxicity to the host
What are three examples of natural defense mechanisms in animals?
Mucociliary escalator in the respiratory tractFlushing effect of urinationGut normal flora
What are of primary importance in preventing and/or controlling infection in patients?
Natural defence mechanisms
What are the four quadrants of the antimicrobial spectrum?
Gram positive aerobesGram negative aerobesObligate anaerobesPenicillinase producing Staph
What are the six atypical bacterial species that don’t fit into the antimicrobial spectrum quadrants?
RickettsiaMycoplasmaChlamydiaBorreliaBartonellaMycobacterium
How does bacterial resistance occur?
Antibacterial agents preferentially select for resistant populations of bacteria
When should antibacterial agents be used?
Definitively diagnosed bacterial infectionLikely diagnosis when all signs and data are consideredBelieved likely to progress without therapyWould cause critical illness if it occurred and was not treated
What is the main type of antibacterial therapy used?
Empirical therapy - don’t know for sure what bacteria is but use the best possible drug with the signs shown
What should you base your prescription of antibacterial drugs on?
Clinical problem and the most likely organisms to be pathogens in that site
What is strongly recommended if therapy fails or infection immediately recurs after therapy?
Culture and sensitivity
What could be given if you do not want to give antibacterials but owner feels something should be done?
Vitamin therapy - no resistance and little to no side effects
What are the clues that a bacterial infection is present?
Heat, redness and swellingPyrexiaNeutrophiliaBacterial cause common for signs
Is vomiting without diarrhoea indicative of antibacterial therapy?
No - no bacteria that cause this
Should antibacterial therapy be considered for a cat less than 10 with haematuria?
No - feline idiopathic cystitis - resolves in 5-7 days with no real treatment
Why is it rare for cats presenting with urine problems for the cause to be bacterial?
Have a very concentrated urine that bacteria are unable to survive well in
What seven things should be considered before providing antibacterial therapy?
Predict likely bacteria?Predict susceptibility?Is culture needed/feasible?Pharmacokinetic factors?Side effects or increased patient risk?Client compliance issues?Cost considerations?
What are the five factors that affect the success of antibacterial therapy?
What bugs live where?Bacterial susceptibilityDistribution to site of infectionLocal conditionsClient compliance
What three main places do infections come from?
EnvironmentOther animalsWithin
If a drug is not susceptible in vitrohow will it work in vivo?
Generally resistant in vivo
Why might a drug only be possibly effective in vivoif pathogen is sensitive in vitro?
Variety of pharmalogical, host and bacterial factors affect effectiveness in vivo
What is MIC?
Minimum inhibitory concentratin
Define MIC
Lowest concentration of drug that will inhibit bacterial growth
What level of MIC is used to determine therapeutic dose?
MIC90 - concentration that will inhibit 90% of isolates of a bacterial species
Which antimicrobials cause inhibition of cell wall synthesis?
PenicillinsCephalosporinsBacitracin