Antimicrobials Flashcards
Why and how are antibiotics used?
▪ Animals are vulnerable to some of the same bacterial infections as
people and can be treated with antibiotics
▪ Antibiotics are used in animals to treat, control and prevent diseases
Why and how are antibiotics used?
▪ Animals are vulnerable to some of the same bacterial infections as
people and can be treated with antibiotics
▪ Antibiotics are used in animals to treat, control and prevent diseases
Is antibiotic use regulated?
▪ The FDA reviews and approves animal medicines using the same
standards and processes as those used for human medicine.
All medically-important antibiotics used in animal feed and water are under the control of ?
licensed veterinarians
Interventions reduce the risk of bacteria transferring
from food animals to people
What poses the greatest risk to humans?
▪ Risk of antibiotic resistance is mostly due to human healthcare use
▪ According to the U.S. Centers for Disease Control (CDC), overuse
and misuse of antibiotics in all settings allows the development of
resistant bacteria.
▪ The risk of antibiotic use in animals is extremely low compared to
uses in human healthcare settings
Increase in AM use –> risk to human and animal health.
Resistant genes are emerging
Define antibiotics
Antibiotics are medicines that have activity against bacteria. They may function by either killing the bacteria (bactericidal) or by inhibiting the growth and proliferation of bacteria (bacteriostatic) allowing the animal’s immune system to more effectively fight a
bacterial infection. Antibiotic treatment stops the growth of a bacterial infection so the host (i.e. the animal) can eliminate it. The animal can then recover and return to health.
What is the antibacterial spectrum?
Antibacterial spectrum: Range of activity of an antibiotic
❑ A Broad spectrum
Antibiotic that can inhibit wide range of Gram (+) and Gram (-) bacteria
e.g. Carbapenems, 3-4 generation of Cephalospofrins
❑ A Narrow spectrum
Antibiotic that is active only against a limited number of bacteria
e.g. penicillin, 1-2 generation of Cephalosporins
Gram (-) bacteria
In 1884, found membrane protein peptidoglycan (some drugs inhibit and block MP synthesis and transfer). Bacteria with thick PG = gram + and become purple when stained with a Gram stain. Bacteria with thin PG = gram - and become pink when stained with a Gram stain.
Gram (+) Staphylococcus aureus
Gram - have more lipopolysaccharides which is why they stain pink in color
Selective toxicity of the drug for invading organism:
Mycoplasma do not have penicillin binding proteins which is why it is resistant to penicillin.
What are the 6 selection questions used to select an antimicrobial agent?
➢ Is an antimicrobial agent required – is there an infection that will respond to your treatment? (avoid: “just in case”)
➢ Where is the infection (which organ/tissue) – what are the drug access problems to be overcome?
➢ Which pathogen (s) are usually found at the location of the infection?
➢ Which antimicrobial agent has the necessary PK properties to get to the location and also will get there at a concentration above the MIC so that the MIC is below the breakpoint?
➢ What dose and route is necessary to achieve the desired effect?
➢ How long should the treatment be for?
What are the additional factors to help with selecting an antimicrobial agent?
➢ A bactericidal component may be preferable to bacteriostatic compound
in immunocompromised animals
➢ Toxicity and cost limit selection of an antimicrobial drug
➢ In food-producing animals, residues in milk and meat requiring the need for
withdrawal times before slaughter
➢ Drugs plasma concentration governs the dosing intervals on a treatment protocol but it is the tissue residence times that govern the pre-slaughter withdrawal times in production animals
What are the Mechanisms by which bacteria manifest resistance?
➢ Bacteria may produce enzymes, which may inactivate the drug. Drugs themselves do not cause any mutations, but may exert some selection pressure.
➢ The permeability to or uptake of the drug may be decreased. Transport out of the cell (multi-drug efflux transporters) may be increased.
➢ Alteration of the drug receptor or binding site may result in reducing the affinity
➢ Bacteria may develop alternative metabolic /synthetic pathways to bypass
or repair the effects of the drug
False color transmission electron micrograph
Varies in terms of shapes, structure, aerobic/anaerobic
Structure: single cell organism, no cell nucleus, lack interor membrane and organelles, use flagella, pilus. They are simple cell organisms.
What are the MOAs of Antibacterial drugs?
Animal cells do not make peptidoglycans. This mode of action is an example of selective toxicity to bacterium. We will have no side effects if we target peptidoglycans. Prokary ribosomes are smaller than eukary; additionally they are floating in cytoplasm.
1. These drugs including penicillin and beta lactams block production of PG inhibiting cell wall biosynthesis.
2. Ribosomes differ from mammalian cells
4. Particular enzymes in bacteria?
Fill in the blanks
PBP = penicillin binding proteins
Betalactams are acting through PBP and inhibiting them.
Mold juice –> barrier –> Staphylococcus did not grow
▪ Group of antibiotics originally obtained from Penicullium mold
▪ Most penicillins in clinical use are chemically synthesized from _______-produced penicillins
▪ These antibiotics all have a common element in their molecular structure:?
Red = Beta lactam
naturally
a four-atom ring known as a β-lactam
List the Beta Lactam Antibiotics
Penicillin, Cephalosporin, Carbapenam, Monobactam
How is penicillin classified?
List the Beta-lactamase inhibitors?
What are penicillin-resistant penicillins? What are they used for?
What broad-spectrum penicillins? What are they used for?
What potentiated penicillins? What are they used for?
What is the PK of penicillins?
