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DWT Exam 2 > Pharmacology Antimicrobials > Flashcards

Pharmacology Antimicrobials Flashcards

1
Q

What is the Minimum Inhibitory Concentration (MIC)?

A

The lowest concentration of drug that INHIBITS visible bacterial growth

Ex: MIC90 means the concentration for inhibiting 90% of the bacteria

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2
Q

What does Minimum Bacterial Concentration (MBC) mean?

A

The lowest concentration of a drug that KILLS 99.9% of bacteria

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3
Q

What does bacteriostatic mean?

A

Stops bacteria from multiplying; does not kill them and requires an immune competent patient

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4
Q

What are bacteriostatic drugs not good for?

A

Sepsis
Neonates
Animals on glucocorticoids
Animals on cancer chemotherapy

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5
Q

What does bactericidal mean?

A

Kills bacteria if concentrations reach MBC for a certain period of time

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6
Q

What type of anti microbial drug is best for immunosuppressive animals?

A

Bactericidal antimicrobials

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7
Q

What are bactericidals preferred for?

A

Sepsis
Neonates
Animals on glucocorticoids
Animals on cancer chemoerapy
Severely I’ll patients

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8
Q

What does postantibiotic effect (PAE)mean?

A

Stays in animal after plasma concentrations decline below the MIC/MBC

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9
Q

What are the mechanisms of postantibiotic effect?

A

1) decrease virulence of the bacteria
2) development of abnormal cell wall or septum
3) increased susceptibility to host defenses
4) persistence at sites of infection

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10
Q

Does postantibiotic effect occur in all drugs?

A

No, only some

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11
Q

Is the postantibiotic effect bacteria dependent or independent?

A

Dependent

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12
Q

What is the relationship between pharmacokinetics- pharmacodynamic interactions?

A

Used to predict the success of antimicrobial therapies & to relate concentration of drug to MIC of the pathogen

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13
Q

What are “Drug-Bug” interactions?

A

How long the postantibiotic effect lasts based on the antibiotic & the specific bacteria you are trying to treat

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14
Q

What are Time-Depemdent antibiotics?

A

Duration plasma concentration is above the MIC for over 24 hours

Treatment success is based on how long a 24 hour period the concentration in the plasma are above the MIC of that bacteria

Ex: Beta- lactation antimicrobials

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15
Q

What are Concentration- Depemdent antibiotics?

A

Cmax:MIC

Ratio of the maximum plasma concentration to the MIC

Ex: Aminoglycoside antimicrobials

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16
Q

What are concentration/Time-Depemdent antibiotics?

A

AUC:MIC

Ratio of the AUC from 0 to 24 hours to the MIC

Ex: flueroquenolones

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17
Q

What are the 3 categories of antibiotic mechanism of action?

A

1) Inhibit cell wall synthesis and function
2) Inhibit nucleocapsid acid synthesis and function
3) Inhibit protein synthesis specifically the 50s subunit and the 30s ribosomal subunit

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18
Q

What is the difference between narrow spectrum and broad spectrum antimicrobial?

A

Narrow spectrum antimicrobials implies activity against a limited subset of bacteria while broad spectrum implies activity against a wide range of bacteria

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19
Q

What does spectrum of activity tell you?

A

That a bacteria CAN BE affected by the antimicrobial

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20
Q

True or False: individual isolates of bacteria may be resistant to an antimicrobial even though they are part of the spectrum

A

True

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21
Q

What are the 6 quadrants of the antibacterialspectrum

A

1) aerobic, gram + streptococci
2) aerobic, gram + staphylococci
3) aerobic, gram - respiratory pathogens
4) aerobic, gram - enteric pathogens
5) anaerobic gram +
6) anaerobic gram -

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22
Q

What does additive/indifferent mean when discussing antmicrobial drug interactions?

A

the combination of 2 antimicrobials to extend the spectrum

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23
Q

What is antagonism in relation to antimicrobial drug interactions?

A

the combination of the drugs cancels the effects of both of the drugs equally

Ex: Penicillin + tetracycline

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24
Q

What are the characteristics of intravenous drug route of administration?

A

Used with systemic illness
highest concentration
highest risk for adverse effects

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25
Q

What are the characteristics of IM/SQ drug route of administration?

A

Bioavailability often complete
risk of drug toxicity is less than IV
Dehydration/shock will affect absorption

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26
Q

Why is the oral route contraindicated?

A

Can cause ileus/colitis
Malabsoprtion
drug interactions

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27
Q

what are the main reasons why we choose an antibiotic?

A

Availability
Ease of use
Adverse effects
Cost
Species being treated

28
Q

What drug classes do beta-lactam antibiotics include?

A

Penicillins
Cephalosporins
Carbapenema
Monobactams

29
Q

What is the mechanism of action for beta-lactams?

A

Penetrate the outer cell wall
Bind to & inhibit penicillin binding proteins
Inhibition of cross-linking
Opens channels through the cell wall to create pores which allows fluid into the cell causing swelling & death

30
Q

Are beta-lactose’s bacteriostatic or bactericidal?

A

Bactericidal

31
Q

What are the pharmacokinetics of Beta-lactams?

A

Low plasma protein binding
Hydrophilic
Do not distribute well to protected sites
Short half-life (frequent dosing)
Some post antibiotic effect against gram + bacteria

32
Q

What are the pharamcokinetics of beta-lactam metabolism and elimination?

A

Minimal metabolism
Elimination through glomerular filtration and tubular secretion

33
Q

Are beta-lactams a good choice for cystitis and if so why?

A

Yes, because they are eliminated through glomerular filtration & tubular secretion means that there are very high concentrations in the urine

34
Q

What are the 4 different penicillin groups?

A

Benzylpenicillins
Aminopenicillins
Extended spectrum penicillins
Anti-staphylococcal penicillins

35
Q

What are benzylpenicillins effective against?

A

Gram positives
streptococcus species
anaerobes

36
Q

Are Benzylpenicillins effective against gram negative bacteria why or why not?

A

No because gram negative bacteria are usually resistant

37
Q

What inactivates Benzylpenicillins and why?

A

Beta-lactamases because it breaks down the beta-lactam ring

38
Q

What is an example of a benzylpenicillin drug?

A

Penicillin G

39
Q

What are the routes of administration for Penicillin G and their characteristics?

A

Oral absorption is limited because it degrades in gastric acid
IM/SQ complexed with procaine or benzathine which give it a longer half life and can be dosed less frequently

40
Q

Why does benzathine penicillin suck as a drug choice

A

Never reaches therapeutic concentrations

41
Q

What are the key concepts of Penicillin G?

A

Effective against streptocci & anaerobes
Susceptable to Beta-lactamases
Inadvertant IV injection of procain penicillin causes severe procain reactions
Benzathine formulations do not reach therapeutic concentrations

42
Q

What are the key concepts of Aminopenicillins?

A

Effective against streptococci and anaerobes
Increasing gram-negative spectrum
Susceptible to beta-lactamases unless combined with a BL1

Ex: Amoxicillin + calvulanic acid & ampicillin +sulbactam

43
Q

What are the key concepts of Aminopenicillins?

A

Effective against streptococci and anaerobes
Increasing gram-negative spectrum
Susceptible to beta-lactamases unless combined with a BL1

Ex: Amoxicillin + clavulanic acid & ampicillin +sulbactam

44
Q

What is the number one antibiotic chosen for dogs and number two in cats?

A

Amoxicillin + Clavulanic acid

45
Q

What are Extended spectrum penicillins used for?

A

Drugs in this class rarely used clinically and NOT on test

46
Q

What are anti-staphylococcal penicillins effective against?

A

Little activity against gram negative or anaerobic organisms

47
Q

what is the key concept of anti-staphylococcal drugs

A

bacteria reported resistant to oxacillin should also be considered to be resistant to all other beta-lactam antibiotics

48
Q

What drugs are anti-staphylococcal?

A

Methicillin
Oxacillin

49
Q

What are the classifications of cephalosporins?

A

1st, 2nd, 3rd, 4th Generations

50
Q

What are the characteristics of 1st generation cephalosporins?

A

Effective against gram positive bacteria including beta-lactamase positive staphylococci
Commonly prescribed in dogs

51
Q

What drugs are in the 1st generation cephalosporins?

A

Cefazolin
Cephalexin

52
Q

What are the characteristics of 2nd generation cephalosporins?

A

Greater activity against gram-negative bacteria
Effective against gram positive bacteria

53
Q

What are the characteristics of 3rd generation cephalosporins?

A

has the most activity against gram-negative bacteria
still retain activity against gram positive but should use 1st gen if treating these
Not used clinically if used judiciously

54
Q

What drugs are in the 3rd generation cephalosporins?

A

Ceftior, cefovecin, cefpodoxime proetil

55
Q

Why should 3rd generation cephalosporins be avoided?

A

Because they could lead to antibiotic resistance and these drugs are key in human medicine

56
Q

What is cephalexin used for in dogs and cats?

A

Dermatitis caused by non-methicillin/oxacillin resistant staphylococci

57
Q

What is cefazolin used for in dogs and cats?

A

IV use
Extralable use
Surgical prophylaxis administerd 60 min of incision

58
Q

what is cefpodoxime used for in dogs?

A

skin and soft tissue infections
Longer half-life (once daily dose)
Prodrug- ester improves oral absorption (proxetil)

59
Q

What is Cefovecin used for?

A

Treatment of skin infections of dogs & cats
single SQ dose
has a long half-life due to high affinity protein binding
Provides therapeutic concentrations for up to 14 days
#2 antibacterial in cats

60
Q

What is ceftior used for?

A

approved for use in dogs, horses, chickens. turkeys, cattle, goats, sheep and swine

Ex: ceftiofur crystalline free acid (Excede)

61
Q

What are the characteristics of ceftiofur crystalline free acid (Excede)?

A

Long acting (half-life due to extended-release formulation)
singe SQ dose at the base of the ear for cattle
Single IM dose in swine
IM dose in horses repeated every 4 days
Injection site reactions are common!

62
Q

What is the one cephalosporin drug that can be used in major food producing species as long as the other label indications are met?

A

Cephapirin

63
Q

What are the possible adverse effects with beta-lactam antibiotics?

A

Relatively rare
Hypersensitivity reactions
Cross-reactivity between penicillins and cephalosproins may exist
at high concentrations can inhibit GABA
CNS excitement & seizures
Procaine reactions
GI effects (dogs/cats vomiting) (horses/rabbits colitis)

64
Q

What animal should procain penicillin never be given IV to?

A

Horse

65
Q

What are the mechanisms of resistance for beta-lactam antibiotics

A

Methicillin-resistance (MecA gene encodes for penicillin bidning protein and creats very low bidning affinity for all beta-lactam antibiotics

Enzyme mediated degradation #1 mechanism

Reduced penetration of drug into bacteria

DWT Exam 2 (6 decks)

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