Terminology
What is a “germ” ?
a microorganism causing disease : a pathogenic agent (such as a bacterium or virus)
What test can be done to determine which antimicrobials will be effective?
Culture and Sensitivity (C&S)
Not including transmission. What are 2 OTHER methods that bacteria have of resisting antimicrobials?
There are some cases a bacteria has the ability to grab the antibiotic and pump it back out before it has a change to image the bacterium
While still others develop an enzyme capable of digesting and destroying the antibiotic molecule
This drug family mostly works on Gram + bacteria
Is time dependent and bacteriocidal and only effective against actively dividing cells
It is a good option for treating urinary bacterial issues.
It is the most commonly used in Vet Med
Penicillin(s)
These are small channels in the outer capsule of gram-negative bacteria that allow some antibiotics to gain access the interior of the bacteria
Porin (like a pore)
Antimicrobials are
Compounds used to kill or inhibit microbial growth
Some antimicrobials are __________ dependent while others are ___________ dependent.
Time (bacterioSTATIC or bacterioCIDAL)
Concentration (bacterioCIDAL)
What is required after giving a food producing animal a course of antibiotics and before sending it off for processing.
The correct withdrawal period
The following items are known as ________________
Clavulanic acid, Sublactam , Procaine, Benzathine, Trihydrate
Penicillin adjuncts
Clavulanic acid - B-lactamase inhibitor
Sublactam - B-lactamase inhibitor
Procaine - Incorporated into PenG to create a suspension
Benzathine - Incorporated into PenG to create a longer acting suspension
Trihydrate - formulated into amoxicillin or ampicillin to create a slow-release suspension
A dog is being treated for a Staphylococcal infection with an antibiotic that has a MTD that is lower than the laboratory-determined MIC for this drug-pathogen relationship. Should this antimicrobial be used?
No
The MIC MUST be lower than the MTD in order to be considered susceptible.
What is the goal of antimicrobial therapy?
To kill or inhibit specific pathogens while not harming the host
What does MIC stand for?
What does MTD stand for?
Briefly describe what these mean.
MIC= Minimum inhibitory concentration
MTD= Maximum tolerated dose
MIC= minimum amount of drug that can be given while still being effective
MTD= maximum that a patient can safely handle
These 5 terms are known as: ___________________
Cell Wall, Cell Membrane, Ribosomes, Critical Enzymes of Metabolites, Nucleic Acids
Mechanisms of Action (MOAs)
This is the central structural component of any penicillin or cephalosporin molecule _______________
BETA (B) - LACTAM RING
When penicillin adjuncts are added to the formulation this creates __________
Potentiated penicillins
The adjuncts will "sacrifice" themselves to the B-lactamase enzyme so that the penicillin can bypass it unaffected and do its job against the bacteria's cell walls.
Successful antimicrobial therapy is based on what two levels?
Which level MUST be the lower of the two?
Based on the MIC and MTD.
The MIC MUST be lower than the MTD.
How does antimicrobial resistance occur?
It can result from the misuse of antimicrobials (too low of a dose or other inappropriate administration). Also called selection pressure.
Random genetic mutations.
Wrong antimicrobial for the type of infection.
When the vet makes a selection of a particular antimicrobial drug before the results of a culture and sensitivity are returned it is referred to as: _________
Empiric treatment (or therapy)
This term describes any Staphylococcus bacterial strain that is resistant to a particular extended-spectrum antibiotic
MRSA (METHICILLIN-RESISTANT STAPHYLOCOCCUS AUREUS)
Milk is frequently tested for the presence of penicillins because they are commonly used to treat what in dairy cattle? ______________
They are commonly used to treat mastitis in dairy cattle
These antimicrobials SLOW growth: _________
These antimicrobials KILL: __________
-static (slows growth)
-cidal (kills)
What is Vertical Transmission?
What is Horizontal Transmission?
Vertical Transmission - the passing of this resistant genetic trait to the daughter cells and all subsequent generations of the original bacterium
Horizontal Transmission - when a bacteria shares a piece of DNA to another unrelated bacteria called a plasmid
A bacteria that needs oxygen to survive ___________
Whereas a bacteria that does not need oxygen to survive ______________
Aerobic
Anaerobic
The vet writes a prescription for a penicillin and tetracycline for a particularly hard to control infection, will these two drugs work well at controlling the problem?
No they will not.
Penicillin is only effective against actively dividing cells. To also prescribe a bacteriostatic drug will slow the cell growth and make the penicillin ineffective.
Penicillin-G comes in 3 formulations that go by different routes.
The aqueous solution can go by which routes?
The two suspensions can go by which routes?
EXTRA: how is the concentration expressed?
Aqueous = IV, IM, SQ
Suspensions = Im or SQ
Suspended with procaine = Q24H
Suspended with Benzathine = Q3-5Days
Extra: Example on slide = 300,000 units/1mL