Antimicrobials Flashcards
What is antimicrobial stewardship?
Choosing antimicrobials wisely to we have optimal dose, therapy, and route of admin targeting specific bacterial to reduce the emergence of resistant bacteria
A nonselective, toxic chemicals which are safe to be applied to the skin to kill microorganisms, but not safe to be given orally or parenteraly
Antiseptics
What are the components of efficacy?
Spectrum - gram (+ or -), ability to treat specific organism
Resistance
Can the drug get to the site of action
Concentration vs time-dependent
To maximize clinical efficacy doses should be ________________ for concentration dependent drugs and ________________ for time dependent drugs
High; regular
How does drug efficacy relate to a time-dependent drugs?
T>MIC
Amount of time that the drug remains above the minimum inhibitory concentration
T/F: for time-dependent drugs, higher concentrations at the site of infection will improve efficacy of the drug
F
What antimicrobials are considered to be time-dependent
Penicillins and cephalosporins
How does efficiency relate to concentration-dependent drugs
Peak concentration being very high concentration at the site of infection
Cmax 10x the MIC
Do time-dependent or concentration-dependent drugs usually exhibit long post-antibiotic effect
Concentration dependent
What antimicrobials are considered to be concentration dependent?
Aminoglycosides
Fluoroquinolones
What type of drug does efficacy relates to both time and concentration
AUC/MIC
Dosage combined with frequency is important
What are the antimicrobials that have AUC/MIC index
Macrolide s
Lincosamides
Tetracycline
Fluoroquinolones
What are the antimicrobials that are distributed to the ECF
Beta-lactams (penicillins and cephalosporins )
Aminoglycoside
What. Are the antimicrobials that are distributed through the total body water
Chloramphenicol Clindamycin Doxycycline Doxycycline Quinolones Sulfonamides
What antimicrobials will concentrate in the urine?
B-lactams
Aminoglycoside
Quinolones
Sulfonamides
What antimicrobials concentrate in the bile?
Doxycycline
Erythromycin
Rifampin
What antimicrobial accumulate in WBCs?
Clindamycin
Erythromycin
Quinolones
Rifampin
What antimicrobials will cross the BBB?
Chloramphenicol Doxycycline Quinolones Metronidazole Rifampin Potentiated sulfonamides
Inflammation-> penicillins and some cephalosporins
What antimicrobials do NOT penetrate the BBB?
Aminoglycoside
Some cephalosporins
Clindamycin
Erythromycin
How can inflammation alter antimicrobial drug delivery to site of infection?
Increase blood flow
Higher capillary permeability
Chronic inflammation -> decrease efficacy if there is puss/fibrosis
Change in pH
Reduced local oxygen-> reduced function of some drugs
What are adverse effects that can occur due to a drug?
Toxicity Idiosyncratic/ dose-dependent Species specific Irritant or life-threatening Reversible or not ?
Can B-lactams have a toxic effect? Why? Why not?
Generally not
Target the cell wall of the bacterium
Can sulfonamides and fluoroquinolones have a toxic effect? Why or Why not?
Generally non toxic
Have a higher affinity for the bacterial target enzyme than the mammalian enzymes
Can animoglycosides have a toxic effect? Why or why not?
Yes
Accumulate in renal cells and otic hair cells causing damage to those organs
Can doxycyline cause toxicity? Why or why not?
Yes
Can cause severe irritation to the esophagus from direct tissue irritation leading to esophageal stricture
How does therapeutic index usually relate to adverse events?
Wide therapeutic index -> rarely significant adverse effects (eg amoxicillin)
Narrow therapeutic index-> significant risk (e.g. aminoglycoside cause renal toxicity)
What adverse effect with enrofloxacin cause in cats?
Retinopathy
Enrofloxacin (fluoroquinolones) can cause what adverse effect in young animals?
Joint damage
What breed has a higher incidence of hepatotoxicity caused by sulfonamides?
Doberman retrievers
What adverse effect will penicillins have on small herbivores (guinea pig, rabbits)
GI microflora disruption
What are the classes of antibiotics commonly used in veterinary medicine (12)
Aminoglycosides Amphenicols B lactams B lactamase inhibitors Cephalosporins Fluoroquinolones Lincosamides Macrolide Nitroimidazoles Penicillins Sulfonamides and DHFR inhibitors Tetracyclines
What are the MOAs of antibiotics?
Inhibit the cell wall synthesis
Disrupt the cell membrane
Inhibition of protein synthesis
Inhibition of DNA/RNA synthesis
What are characteristics of antibiotics that inhibit cell wall synthesis ?
Bactericidal
Greatest effect on actively dividing bacteria
Often good against gram positive bacteria
What antibiotics inhibit cell wall synthesis ?
B-lactams: penicillins, cephalosporins, carbapenems
Bacitracin
Glycopeptides (vancomycin)
What are the general characteristics of antimicrobials that disrupt the cell membrane ?
Bactericial
Good against gram negatives
More risk of toxicity (when given systemically-> only use topically)
Do not require actively dividing bacteria
What antimicrobials works by disrupting the cell membrane?
Polymixin
What are the general characteristics of antimicrobials that inhibit protein sysnthesis?
Often bacteriostatic
May be more effective during replication
Toxicity varies between drugs (unrelated to MOA)
What are the antimicrobials that inhibit protein synthesis?
Macrolide and lincosamides
Amphenicols
Tetracyclines
Aminoglycosides
Nitrofurans
What are the general characteristics of antimicrobials that inhibit DNA or RNA synthesis
Toxicity variable
Generally considered relatively safe
Microbial targets are more sensitive than mammalian enzymes
What are the antimicrobials that target DNA or RNA synthesis ?
Fluoroquinolones
Sulfonamides
Nitroimidazoles
Rifamycins
You see a cat with esophageal stricture, what antimicrobial might be related?
Doxycyline or clindamycin
-> causes irritation to the esophagus –> chase with water
Pulmotil and Micotil both have the active tilmocosin, are these drugs interchangeable in treating cattle for respiratory disease?
Nope
Pulmotil is mixed into food for pigs-> not approved in cattle because it will go to rumen and just sit there, will not be distributed to the tissues
Micotil is given SQ to cattle
You need to treat your pet bunny named Bugs for a respiratory infection. You have the following availaiable for your prescribing needs, which shhhould you give?
Enrofloxacin (fluoroquinolones )
Cephalexin (cephalosporins )
Amoxicillin (penicillin)
Clindamycin (lincosamides)
Enrofloxacin
The others will disrupt the bunny GI microflora (disbiosis) -> fatal x_x
Why would it be acceptable treatment to give Tulathromycin (macrolide) as a single dose rather than over a few days to treat respiratory disease?
Macrolide have a serum half-life of 60-90hrs
They accumulate in the pulmonary system and phagocytes where there half-life is 6days.
Can ampicillin and amikacin be used in the same patient to synergistically treat an infection?
Yes
Ampicillin (penicillin) and amikacin (aminoglycoside) have synergistic effects
BUT…
Cannot be mixed in the same syringe -> aminoglycoside will inactivate penicillin in vitro
Can you used amphenicol to treat your moo cows with bovine respiratory disease? What about in a dog?
Well you could… but then you might kill the person who eats that cow.. (you win some, you lose some)
Amphenicol s are banned in food animals -> residues -> fatal aplastic anemia in humans
You can use this is dog
