Antibiotics Flashcards Preview

PHA2 > Antibiotics > Flashcards

Flashcards in Antibiotics Deck (135)
Loading flashcards...
1
Q

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

A

Gram positive

2
Q

Where do gram positive bacteria secrete their B-lactamases?

A

into the intracellular fluid outside their cell wall.

3
Q

Where do gram negative bacteria secrete their B-lactamases?

A

In the periplasmic space between their cell wall and cell membrane

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

4
Q

Name two B-lactamase inhibitors.

A

Clavulanic acid or Sulbactam

5
Q

What bacteria do penicillins generally work on?

A

Gram positive.

As well as anaerobes and spirochetes

6
Q

Are penicillins bacteriostatic or bacteriocidal?

A

Bacteriocidal

7
Q

Are penicillins concentration or time dependent?

A

Time dependent

8
Q

Do penicillins cross the BBB?

A

NO.

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

9
Q

How are penicillins excreted?

A

Actively in the urine

10
Q

Contraindications with penicillins?

A

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

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

11
Q

Name the 5 penicillins we know.

A
Penicillin G
Ampicillin/Amoxicillin 
Amoxicillin-Clavulanic acid
Cloxacillin
Ticarcillin
12
Q

Penicillin G is used more in SA or LA?

Because of this how is it usually given?

A

LA.

parenteral.

13
Q

How is Ampicillin given and how is Amoxicillin given?

A

Ampicillin - parenterally
Amoxicillin - orally

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

14
Q

What are the benefits of using Amoxicillin-Clavulanic acid?

A

inhibits B-lactamases to increase efficacy

15
Q

What is Cloxacillin used for?

A

B-lactamase stable penicillin used for mastitis in cattle

16
Q

What is Ticarcillin used for?

A

‘anti-pseudomonas’ penicillin occasionally used topical in the ear

17
Q

What are first generation cephalosporins effective against?

A

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

**Cephalosporins are more broad spectrum than penicillins

18
Q

What are second generation cephalosporins effective against?

A

Gram positive with a greater efficacy against gram negatives.

19
Q

What are third generation cephalosporins effective against?

A

Gram negatives with less gram positive activity

20
Q

What are fourth generation cephalosporins effective against?

A

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

*Not used in vet ed usually bc ‘big gun’

21
Q

Are cephalosporins time or concentration dependent?

Are they bactericidal or bacteriostatic?

A

Time dependent and bacteriocidal

22
Q

Do cephalosporins cross the BBB?

A

Nope.

but well absorbed orally

23
Q

Contraindications of cephalosporins?

A

Reptiles, birds, and hypersensitivity patients

Do NOT give orally to horses, ruminants, guinea pigs

24
Q

Name three first generation cephalosporins.

A

Cephalexin
Cefazolin
Cephapirin

25
Q

What is cefazolin used for?

A

First generation cephalosporin used prophylactically during surgery

26
Q

What is cephapirin used for?

A

Mastitis in cattle via intramammary infusion

27
Q

What is Cefoxitin used for?

A

SECOND generation cephalosporin for serious infections

28
Q

Name three third generation cephalosporins.

A

Ceftiofur (foot rot/resp dx)
Cefovecin
Cefpodoxime

29
Q

What is Cefovecin used for?

A

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

treats pyoderma (staph - dog, pasteurella - cats)

30
Q

How does cefpodoxime become active?

A

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

31
Q

What bacteria do carbapenems work on?

A

Positive, negative, pseudomonas.

32
Q

What is dangerous about Carbapenems?

A

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

33
Q

Are carbepenems time or concentration dependent?

Are they bacteriocidal or bacteriostatic?

A

Time dependent and bacteriocidal.

34
Q

Do carbapenems cross the BBB?

A

YES.

35
Q

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

A

Phlebitis and Seizures.

**Meropenem is a safer alternative given SC

36
Q

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

A

Vancomycin and Bacitracin.

37
Q

How does vancomycin work?

A

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

38
Q

Is Vancomycin time or concentration dependent?

Is it bacteriocidal or bacteriostatic?

A

Time dependent and bacteriocidal

39
Q

What does vancomycin work againt?

A

Almost all gram positives including MRSA.

Gram negatives are generally resistant

40
Q

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

A

Vancomycin

41
Q

Does Vancomycin cross the BBB?

A

Nope.

42
Q

Adverse effects of Vancomycin?

A

histamine release, nephrotoxicity, and ototoxicity.

*Do NOT use in food producing animals

43
Q

How does bacitracin work?

A

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

44
Q

What is Bacitracin effective against?

A

Gran positive.

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

45
Q

How do Beta-lactams work?

A

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

*osmotic pressures eventually lead to cytolysis

46
Q

What are the categories of Beta-lactam antibiotics?

A

Penicillins
Cephalosporins
Carbepenems/Monobactams

46
Q

What antibiotics affect the cell membrane?

A

Polymyxin B.

47
Q

How does polymyxin B work?

A

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

*doesnt work against gram positive

48
Q

Contraindications of polymyxin B?

A

Toxic, limited to topical use.

Fatal anaphylactic reactions reported in Cats.

49
Q

Name the five groups of drugs that disrupt protein synthesis.

A
Tetracyclines.
Amphenicols.
Macrolides/Lincosamides.
Streptogramins.
Aminoglycosides.
50
Q

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

A

False.

Bacteriostatic

51
Q

How do tetracyclines work?

A

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

52
Q

What are tetracyclines effective against?

A

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

*NOT good against pseudomonas and proteus

53
Q

Are tetracyclines time or concentration dependent?

A

Time dependent

54
Q

Contraindications of Tetracyclines.

A

Chelate divalent cations (drug-drug/drug-fluid interxns)

Antagonistic to penicillins

55
Q

Toxicity issues of Tetracyclines?

A

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

56
Q

Name the 4 tetracyclines we know.

A

Oxytetracycline
Chlortetracycline
Doxycycline
Minocycline (Doxy alternative)

57
Q

What is oxytetracycline and chlortetracycline used for?

A

broad spectrum for large animals

chlortetracycline can be used as feed additive

58
Q

Benefits of Doxycycline.

A

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

59
Q

Risks of Doxycycline.

A

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

Can cause esophageal stricture in cats if not given with water

60
Q

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

A

Doxycycline!

61
Q

How do amphenicols work?

A

Inhibit peptidyl transferase on the 50s ribosomal subunit.

62
Q

Are amphenicals time or concentration dependent?

Bacteriocidal or bacteriostatic?

A

Time dependent and bacteriostatic.

63
Q

Contraindications of amphenicols?

A

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

64
Q

Adverse effects of Amphenicols?

A

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

65
Q

Contraindications of Chloramphenicol use in Cats.

A

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

66
Q

What is Chloramphenicol used to treat?

A

MRSP.

Illegal to use in food animals (use FLORFENICOL)

67
Q

How do Macrolides/Lincosamides work?

A

Inhibit translocation and movement of the 50s ribosomal subunit

68
Q

Name 5 macrolides.

A
Erythromycin
Tylosin
Tilmicosin
Tulathromycin
Azithromycin
69
Q

Name 3 lincosamides.

A

Lincomycin
Pirlimycin
clindamycin

72
Q

Are Macrolides time or concentration dependent?

Bacteriostatic or Bacteriocidal?

A

Time-dependent and bacteriostatic

73
Q

What type of bacteria are macrolides effective against?

A

Gram positive with more anaerobic activity.

74
Q

Macrolides/Lincosamides have cross resistance with what drug?

A

Streptogramin B

75
Q

Contraindications of Macrolides?

A

Rabbits, gerbils, guinea pigs, and hamsters.

Do NOT give oral in adult horses and ruminants

76
Q

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

A

False.

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

77
Q

Why is tilmicosin dangerous?

A

CARDIOTOXIC. Do not give IV. use in LA.

78
Q

What is Tulathromycin used for?

A

Beef and Non-lactating cattle.

Single dose treatment regimen.

79
Q

What is Azithromycin used for?

A

Small animal infections (lasts a long time in phagocytes)

As well as Rhodococcus pneumonia in foals.

80
Q

Cross Resistance with Lincomysin

A

Clindamycin and Erythromycin

81
Q

Don’t use lincomycin in which species?

A

Horses, Ruminents, lagomorphs.

82
Q

What is Pirlimycin used for?

A

Lincosamide used for mastitis via intramammary infusion.

83
Q

What drug is used in SAM to treat toxoplasma?

A

Clindamycin

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

84
Q

Tell me about Streptogramins.

A
  • 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
Q

How do aminoglycosides work?

A

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

86
Q

What are aminglycosides effective against?

A

Gram negative aerobes.

87
Q

Are aminoglycosides time or concentration dependent?

Bacteriostatic or bacteriocidal?

A

CONCENTRATION dependent and bacteriocidal.

88
Q

Aminoglycosides have synergism with what drugs?

A

Penicillins

89
Q

Do aminoglycosides cross the BBB?

A

Nope.

90
Q

Adverse effects of aminoglycosides.

A

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

91
Q

Name four Aminoglycosides.

A

Gentamycin.
Amikacin.
Neomycin.
Apramycin.

92
Q

What is Amikacin used for?

A

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

*better efficacy and lower toxicity than gentamycin

93
Q

How do you treat hepatic encephalopathy using GI flora?

A

“Gut sterilization” using Neomycin

94
Q

Other drugs used for MRSA.

A

Linezolid, Mupirocin, and Fusidic Acid.

95
Q

Name six drug groups that disrupt DNA/RNA synthesis.

A
Sulfonamides. 
Fluoroquinolones. 
Nitroimidazoles. 
Nitrofurans. 
Rifampin. 
Novobiocin.
96
Q

Name four Sulfonamides.

A

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

97
Q

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

A

Erythromycin.

98
Q

What are the three Dihydrofolate reductase inhibitors used with Sulfonamides?

A

Trimethoprim.
Ormetoprim.
Pyrimethamine.

*synergistic with sulfonamides

99
Q

How do sulfonamides work?

A

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

100
Q

Are sulfonamides bacteriostatic or bacteriocidal?

A

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

101
Q

In what environment do Sulfonamides not work well?

A

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
Q

Adverse effects of Sulfonamides.

A

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

103
Q

What is sulfamethoxine used for?

A

Coccidia, shipping fever, foot rot.

104
Q

What drugs do you use to treat toxoplasma?

A

TMS and Clindamycin

105
Q

What is pyrimethoamine-sulfadiazine used for?

A

Protozoal infectins like sarcocystis neurona in EPM (horses)

106
Q

Name four fluoroquinolones.

A

Enrofloxacin.
Pradofloxacin.
Ciprofloxacin.
Danofloxacin.

107
Q

How do fluoroquinolones work?

A

Inhibit DNA-gyrase (topoisomerase) and unwind DNA.

108
Q

What are fluoroquinolones effective against?

A

Gram negatives, mycoplasma, rickettsia, and chlamydia.

109
Q

Are fluoroquinolones time or concentration dependent?

A

CONCENTRATION dependent

110
Q

T/F Fluoroquinolones are more active in pus.

A

False. Less active.

111
Q

Toxicities of fluoroquinolones?

A

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

112
Q

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

A

True.

113
Q

T/F Ciprofloxacin is a metabolite of enrofloxacin.

A

True.

114
Q

How do nitroinidazoles work?

A

Damage to DNA and RNA repair enzymes

115
Q

Name the two most common Nitroimidazoles.

A

Metronidazole and Ronidazole (Tritrichamonas in cats***)

116
Q

T/F Sulfonamides effect thyroid measurements.

A

True.

117
Q

What are nitroimidazoles effective against?

A

very effective against anaerobic bacteria.

118
Q

Are nitroimidazoles bacteriostatic or bacteriocidal?

A

Bacteriocidal.

119
Q

How do nitrofurans work?

A

Nonspecific damage to DNA by blocking oxidative decarboxylation.

120
Q

Are nitrofurans bacteriocidal or bacteriostatic?

A

Bacteriostatic.

121
Q

What are nitrofurans (specifically nitrofurantoin) used for?

A

UTI’s.

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

122
Q

Adverse effect of nitrofurantoin?

A

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

123
Q

What is Nitrofurazone used for

A

Topical wound dressing in horses.

124
Q

How does Rifampin work?

A

inhibits B subunit of RNA polymerase

125
Q

What is rifampin used for?

A

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

126
Q

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

A

TRUE.

bacteriocidal but resistance develops quickly.

127
Q

Contraindications and adverse effects of rifampin?

A

Induces microsomal enzymes (Drug-drug_

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

128
Q

How does Novobiocin work?

A

binds to DNA gyrase to inhibit repair

129
Q

T/F Novobiocin is compatible with macrolides in vitro.

A

FALSE. Novobiocin is incompatible with macrolides in vitro.

130
Q

T/F Resistance develops quickly with Novobiocin.

A

TRue

131
Q

What is Methanamine used for? (Adjunct therapy)

A

Urinary antispetic.

broken down to formalin in urine, requires acidic enviroment.

132
Q

What is Carbadox used for? (Adjunct therapy)

A

gram-negative organisms but potentially carcinogenic

133
Q

What is TrizEDTA used for? (Adjunct therapy)

A

EDTA damages cell surface of gram negatives.

USed for pseudomonas otitis (give prior to antibiotic to increase efficacy)

134
Q

WHat is Silver used for? (Adjunct therapy)

A

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

*can cause permanent discoloration of the skin

135
Q

How can you increase oral absorption of Nitroimidazoles?

A

Give with food.

136
Q

What is Tylosin used for?

A

Macrolide used for antibiotic-responsive diarrhea.