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Flashcards in Antibiotics Deck (135):
1

Which type of bacteria is more susceptible to beta-lactams?

Gram positive

2

Where do gram positive bacteria secrete their B-lactamases?

into the intracellular fluid outside their cell wall.

3

Where do gram negative bacteria secrete their B-lactamases?

In the periplasmic space between their cell wall and cell membrane

**they are inheriently resistant to B-lactamases due to outer membrane

4

Name two B-lactamase inhibitors.

Clavulanic acid or Sulbactam

5

What bacteria do penicillins generally work on?

Gram positive.
As well as anaerobes and spirochetes

6

Are penicillins bacteriostatic or bacteriocidal?

Bacteriocidal

7

Are penicillins concentration or time dependent?

Time dependent

8

Do penicillins cross the BBB?

NO.

but have high concentrations in kidney, synovial fluid, lungs, skin, and soft tissue

9

How are penicillins excreted?

Actively in the urine

10

Contraindications with penicillins?

Do NOT use in reptiles, birds, or hypersensitivity patients.

Do NOT use orally in horses, ruminants, guinea pigs, or chinchillas

11

Name the 5 penicillins we know.

Penicillin G
Ampicillin/Amoxicillin
Amoxicillin-Clavulanic acid
Cloxacillin
Ticarcillin

12

Penicillin G is used more in SA or LA?
Because of this how is it usually given?

LA.

parenteral.

13

How is Ampicillin given and how is Amoxicillin given?

Ampicillin - parenterally
Amoxicillin - orally

*both used for SA and LA (mastitis) gram positives

14

What are the benefits of using Amoxicillin-Clavulanic acid?

inhibits B-lactamases to increase efficacy

15

What is Cloxacillin used for?

B-lactamase stable penicillin used for mastitis in cattle

16

What is Ticarcillin used for?

'anti-pseudomonas' penicillin occasionally used topical in the ear

17

What are first generation cephalosporins effective against?

Gram positive and less susceptible to B-lactamase than penicillins.

**Cephalosporins are more broad spectrum than penicillins

18

What are second generation cephalosporins effective against?

Gram positive with a greater efficacy against gram negatives.

19

What are third generation cephalosporins effective against?

Gram negatives with less gram positive activity

20

What are fourth generation cephalosporins effective against?

Broad spectrum positive and negative, plus pseudomonas and B-lactamase resistant

*Not used in vet ed usually bc 'big gun'

21

Are cephalosporins time or concentration dependent?

Are they bactericidal or bacteriostatic?

Time dependent and bacteriocidal

22

Do cephalosporins cross the BBB?

Nope.
but well absorbed orally

23

Contraindications of cephalosporins?

Reptiles, birds, and hypersensitivity patients
Do NOT give orally to horses, ruminants, guinea pigs

24

Name three first generation cephalosporins.

Cephalexin
Cefazolin
Cephapirin

25

What is cefazolin used for?

First generation cephalosporin used prophylactically during surgery

26

What is cephapirin used for?

Mastitis in cattle via intramammary infusion

27

What is Cefoxitin used for?

SECOND generation cephalosporin for serious infections

28

Name three third generation cephalosporins.

Ceftiofur (foot rot/resp dx)
Cefovecin
Cefpodoxime

29

What is Cefovecin used for?

Third generation cephalosporin that is highly protein bound, given once a week or two weeks.

treats pyoderma (staph - dog, pasteurella - cats)

30

How does cefpodoxime become active?

Pro-drug until GI absorption turns in into an active drug

31

What bacteria do carbapenems work on?

Positive, negative, pseudomonas.

32

What is dangerous about Carbapenems?

They have a greater Post-Antibiotic Effect (PAE) than other B-lactams with a greater toxicity.

33

Are carbepenems time or concentration dependent?

Are they bacteriocidal or bacteriostatic?

Time dependent and bacteriocidal.

34

Do carbapenems cross the BBB?

YES.

35

What are the risks of Imipenem if not given as a slow IV infusion?

Phlebitis and Seizures.

**Meropenem is a safer alternative given SC

36

Name two drugs that work on cell wall synthesis but are not B-lactams.

Vancomycin and Bacitracin.

37

How does vancomycin work?

The glycopeptides bind to NAG and NAM to prevent cross-linking and inhibit cell wall synthesis

38

Is Vancomycin time or concentration dependent?

Is it bacteriocidal or bacteriostatic?

Time dependent and bacteriocidal

39

What does vancomycin work againt?

Almost all gram positives including MRSA.
Gram negatives are generally resistant

40

What drug can you give orally that works againt C. difficile in the GIT?

Vancomycin

41

Does Vancomycin cross the BBB?

Nope.

42

Adverse effects of Vancomycin?

histamine release, nephrotoxicity, and ototoxicity.

*Do NOT use in food producing animals

43

How does bacitracin work?

against the isoprenyl pyrophosphate enzyme responsible for the 'building blocks' of the cell wall.

44

What is Bacitracin effective against?

Gran positive.

*often used in triple antibiotic ointment with neosporin and polysporin.

45

How do Beta-lactams work?

disrupt transpeptidation by binding their beta-lactam ring to the penicillin binding protein

*osmotic pressures eventually lead to cytolysis

46

What are the categories of Beta-lactam antibiotics?

Penicillins
Cephalosporins
Carbepenems/Monobactams

46

What antibiotics affect the cell membrane?

Polymyxin B.

47

How does polymyxin B work?

Antiseptic.
Binds to LPS's and acts as a cationic detergent to disrupt the membrane, making it bacteriocidal.

*doesnt work against gram positive

48

Contraindications of polymyxin B?

Toxic, limited to topical use.

Fatal anaphylactic reactions reported in Cats.

49

Name the five groups of drugs that disrupt protein synthesis.

Tetracyclines.
Amphenicols.
Macrolides/Lincosamides.
Streptogramins.
Aminoglycosides.

50

T/F Most drugs that disrupt protein synthesis are bacteriocidal.

False.

Bacteriostatic

51

How do tetracyclines work?

Inhibiting tRNA of the 30s ribosomal subunit as well as inhibiting MMP's

52

What are tetracyclines effective against?

Positive, Negative, mycoplasma, chlamydia, spirochetes and rickettsial organisms.

*NOT good against pseudomonas and proteus

53

Are tetracyclines time or concentration dependent?

Time dependent

54

Contraindications of Tetracyclines.

Chelate divalent cations (drug-drug/drug-fluid interxns)
Antagonistic to penicillins

55

Toxicity issues of Tetracyclines?

Yellowing of teeth, GI issues, esophageal stricture**, dysbiosis, bitter taste, and cardiac complications with rapid IV injection.

56

Name the 4 tetracyclines we know.

Oxytetracycline
Chlortetracycline
Doxycycline
Minocycline (Doxy alternative)

57

What is oxytetracycline and chlortetracycline used for?

broad spectrum for large animals

chlortetracycline can be used as feed additive

58

Benefits of Doxycycline.

better GI absorption, greater CNS penetration, less renal excretion, and less likely to cause teeth/bone changes.

59

Risks of Doxycycline.

When given IV can cause arrhythmias, collapse, and death.
**especially horses**

Can cause esophageal stricture in cats if not given with water

60

What drug do we use to treat Ehrlichia, Anaplasma, Borriela, and Heartworm management?

Doxycycline!

61

How do amphenicols work?

Inhibit peptidyl transferase on the 50s ribosomal subunit.

62

Are amphenicals time or concentration dependent?

Bacteriocidal or bacteriostatic?

Time dependent and bacteriostatic.

63

Contraindications of amphenicols?

Inhibit hepatic microsomal enzymes (drug-drug interactions) and antagonize macrolides.

64

Adverse effects of Amphenicols?

Bone marrow suppression, idiosyncratic aplastic anemia in humans (chloramphenicol), and GI signs.

65

Contraindications of Chloramphenicol use in Cats.

Metabolized in the liver via glucoronidation normally, therefore more needs to be excreted in the kidney with cats. could lead to toxicity.

66

What is Chloramphenicol used to treat?

MRSP.

Illegal to use in food animals (use FLORFENICOL)

67

How do Macrolides/Lincosamides work?

Inhibit translocation and movement of the 50s ribosomal subunit

68

Name 5 macrolides.

Erythromycin
Tylosin
Tilmicosin
Tulathromycin
Azithromycin

69

Name 3 lincosamides.

Lincomycin
Pirlimycin
clindamycin

72

Are Macrolides time or concentration dependent?

Bacteriostatic or Bacteriocidal?

Time-dependent and bacteriostatic

73

What type of bacteria are macrolides effective against?

Gram positive with more anaerobic activity.

74

Macrolides/Lincosamides have cross resistance with what drug?

Streptogramin B

75

Contraindications of Macrolides?

Rabbits, gerbils, guinea pigs, and hamsters.
Do NOT give oral in adult horses and ruminants

76

T/F erythromycin is used IM in cattle and requires an acidic environment.

False.
It is used IM in cattle but requires an alkaline environment.

77

Why is tilmicosin dangerous?

CARDIOTOXIC. Do not give IV. use in LA.

78

What is Tulathromycin used for?

Beef and Non-lactating cattle.
Single dose treatment regimen.

79

What is Azithromycin used for?

Small animal infections (lasts a long time in phagocytes)
As well as Rhodococcus pneumonia in foals.

80

Cross Resistance with Lincomysin

Clindamycin and Erythromycin

81

Don't use lincomycin in which species?

Horses, Ruminents, lagomorphs.

82

What is Pirlimycin used for?

Lincosamide used for mastitis via intramammary infusion.

83

What drug is used in SAM to treat toxoplasma?

Clindamycin

*Dont use in horses, rodents, ruminants, or lagomorphs

84

Tell me about Streptogramins.

- Type A and B
- Bacteriostatic alone and Bacteriocidal together
- Work on the 50s ribosomal subunit
- Effective against gram positive
- Cross resistance with Macrolides/Lincosamides
- Veterinary one = VIRGINIAMYCIN

85

How do aminoglycosides work?

Prevent attachment of tRNA (proofreading mechanism) to the 30s ribosomal subunit.

86

What are aminglycosides effective against?

Gram negative aerobes.

87

Are aminoglycosides time or concentration dependent?

Bacteriostatic or bacteriocidal?

CONCENTRATION dependent and bacteriocidal.

88

Aminoglycosides have synergism with what drugs?

Penicillins

89

Do aminoglycosides cross the BBB?

Nope.

90

Adverse effects of aminoglycosides.

Post-Antibiotic Effect (PAE)
Nephrotoxic, ototoxic, vestibular injury (gentamicin and tobramycin), auditory injury (Amikacin and neomycin).
*monitor renal parameters closely

91

Name four Aminoglycosides.

Gentamycin.
Amikacin.
Neomycin.
Apramycin.

92

What is Amikacin used for?

Gram negative infections in SA, intrauterine in horses, and intra-articular in septic arthritis foals.

*better efficacy and lower toxicity than gentamycin

93

How do you treat hepatic encephalopathy using GI flora?

"Gut sterilization" using Neomycin

94

Other drugs used for MRSA.

Linezolid, Mupirocin, and Fusidic Acid.

95

Name six drug groups that disrupt DNA/RNA synthesis.

Sulfonamides.
Fluoroquinolones.
Nitroimidazoles.
Nitrofurans.
Rifampin.
Novobiocin.

96

Name four Sulfonamides.

Sulfamethoxine.
Trimethoprim-sulfadiazine.
Pyrimethamine-sulfadiazine.
Sulfasalazine.

97

What drug is combined with rifampin to treat Rhodococcus equi in foals?

Erythromycin.

98

What are the three Dihydrofolate reductase inhibitors used with Sulfonamides?

Trimethoprim.
Ormetoprim.
Pyrimethamine.

*synergistic with sulfonamides

99

How do sulfonamides work?

Compete with PABA from bacteria for an enzyme that synthesizes DNA.

100

Are sulfonamides bacteriostatic or bacteriocidal?

Bacteriostatic when used alone and Bacteriocidal when use more than one (potentiate)

101

In what environment do Sulfonamides not work well?

Pus.
Sulfonamides are less efective when there is an increased amount of PABA (present in pus)

*Also in the rumen they dont do well

102

Adverse effects of Sulfonamides.

Renal damage, crystalluria, KCS, hypersensitivity, and bone marrow suppression

103

What is sulfamethoxine used for?

Coccidia, shipping fever, foot rot.

104

What drugs do you use to treat toxoplasma?

TMS and Clindamycin

105

What is pyrimethoamine-sulfadiazine used for?

Protozoal infectins like sarcocystis neurona in EPM (horses)

106

Name four fluoroquinolones.

Enrofloxacin.
Pradofloxacin.
Ciprofloxacin.
Danofloxacin.

107

How do fluoroquinolones work?

Inhibit DNA-gyrase (topoisomerase) and unwind DNA.

108

What are fluoroquinolones effective against?

Gram negatives, mycoplasma, rickettsia, and chlamydia.

109

Are fluoroquinolones time or concentration dependent?

CONCENTRATION dependent

110

T/F Fluoroquinolones are more active in pus.

False. Less active.

111

Toxicities of fluoroquinolones?

Arthropathy in growing animals, acute blindness in cats***, and bone marrow suppression.

112

T/F Enrofloxacin is more likely to cause cat blindness than pradofloxacin.

True.

113

T/F Ciprofloxacin is a metabolite of enrofloxacin.

True.

114

How do nitroinidazoles work?

Damage to DNA and RNA repair enzymes

115

Name the two most common Nitroimidazoles.

Metronidazole and Ronidazole (Tritrichamonas in cats***)

116

T/F Sulfonamides effect thyroid measurements.

True.

117

What are nitroimidazoles effective against?

very effective against anaerobic bacteria.

118

Are nitroimidazoles bacteriostatic or bacteriocidal?

Bacteriocidal.

119

How do nitrofurans work?

Nonspecific damage to DNA by blocking oxidative decarboxylation.

120

Are nitrofurans bacteriocidal or bacteriostatic?

Bacteriostatic.

121

What are nitrofurans (specifically nitrofurantoin) used for?

UTI's.
Work well in acidic environments and 50% excreted as parent drug in the urine.

122

Adverse effect of nitrofurantoin?

GI signs, brown colored urine, heaptotoxicity, and infertility.

123

What is Nitrofurazone used for

Topical wound dressing in horses.

124

How does Rifampin work?

inhibits B subunit of RNA polymerase

125

What is rifampin used for?

gram-positive, gram-neg, mycobacterium and rhodococcus equi

126

T/F Rifampin is almost always used with other antibiotics.

TRUE.

bacteriocidal but resistance develops quickly.

127

Contraindications and adverse effects of rifampin?

Induces microsomal enzymes (Drug-drug_

teratogenic, red-orange discoloration of body fluids, and hepatitis.

128

How does Novobiocin work?

binds to DNA gyrase to inhibit repair

129

T/F Novobiocin is compatible with macrolides in vitro.

FALSE. Novobiocin is incompatible with macrolides in vitro.

130

T/F Resistance develops quickly with Novobiocin.

TRue

131

What is Methanamine used for? (Adjunct therapy)

Urinary antispetic.
broken down to formalin in urine, requires acidic enviroment.

132

What is Carbadox used for? (Adjunct therapy)

gram-negative organisms but potentially carcinogenic

133

What is TrizEDTA used for? (Adjunct therapy)

EDTA damages cell surface of gram negatives.
USed for pseudomonas otitis (give prior to antibiotic to increase efficacy)

134

WHat is Silver used for? (Adjunct therapy)

Combined with sulfa as a topical and enrofloxacin as an otitis topical.

*can cause permanent discoloration of the skin

135

How can you increase oral absorption of Nitroimidazoles?

Give with food.

136

What is Tylosin used for?

Macrolide used for antibiotic-responsive diarrhea.