Lecture 23: Drugs interfering with Nucleic Acid Synthesis Flashcards

1
Q

The difference between individual sulfonamide agents is based on properties such as ___

A

Rate of absorption, excretion and solubility in urine

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2
Q

What is essential for antibacterial action of sulfonamides

A

A free paramino group

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3
Q

Are sulfonamides bacteriostatic or bacteriocidal

A

Generally bacteriostatic but in urinary tract infections could be bacteriocidal, so good tx of UTI’s

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4
Q

What do sulfonamides compete with for incorporation into folic acid

A

Para-aminobenzoic acid (PABA)

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5
Q

___is an integral part of folic acid synthesis which is necessary for purine and DNA synthesis by bacteria

A

PABA

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6
Q

In presence of sulfonamides susceptible bacteria can’t __, ___ and __

A

Multiply, grow and survive

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7
Q

Why is the mechanism of sulfonamides not relevant to host/mammalian cells

A

Mammalian cells do not synthesize their own folic acid, they uptake it from the environment

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8
Q

What organisms do sulfonamides act on

A

Gram positive and gram negative

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9
Q

What organisms are highly sensitive to sulfonamides

A

Group A streotococci, pneumococci, E. Coli, Nocardia, Actinomyces, Chlamydria, Pneumocytis jiroveci

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10
Q

What is sulfamethazine used for

A
  1. Bacterial pneumonia and BRD
  2. Foot rot and diphtheria in cattle
  3. Acute mastitis in cattle
  4. Bacterial pneumonia in swine
  5. Coccidiosis in chickens
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11
Q

What is sulfadmiethoxine used for

A

Coccidiosis

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12
Q

Which sulfonamide at high doses can precipitate in urine and cause damage to kidney

A

Sulfadimethoxine

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13
Q

Which sulfonamide is approved orally in calves (except veal calves) under 1 month of age and swine for tx of respiratory and enteric infections, especially colibacilliosis

A

Sulfachlorpryidazine

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14
Q

What is the only sulfonamide that can be prepared as the sodium salt at neutral pH and thus can be used in ophthalmic preparations

A

Sulfectamide

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15
Q

What is sulfasazline used for

A

Enteric sulfonamide used for tx of colitis and IBD in dogs and cats

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16
Q

In the large bowel what is sulfasazline cleaved into and what are their specific functions

A
  1. Sulfapyridine- antibacterial agent and RA
  2. 5-ASA- anti-inflammatory (ulcerative colitis)
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17
Q

What are potentiated sulfonamides mixed with

A

Trimethoprim or ormetoprim

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18
Q

Are potentiated sulfonamides bacteriostatic or bacteriocidal

A

Bacteriocidal

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19
Q

How do potentiated sulfonamides change the spectrum of action and resistance

A

Broad spectrum and decrease development of resistance

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20
Q

Trimpethoprim concentrates in ___ in dogs and is used against ___

A

Prostate, prostatitis

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21
Q

What are some adverse effects of sulfonamides

A
  1. Renal crystalluria
  2. Keratoconjuctivitis sicca in dogs
  3. Hypothrombinemia, thrombocytopenia
  4. Arthritis in Dobermans
  5. Decreased thyroid hormone with trimethoprim
22
Q

What male dogs are sulfonamides contraindicated in

A

Male dogs used for breeding because reduces sperm count

23
Q

What is the mechanism of action of fluroquinolones

A

Inhibit bacterial DNA gyrase and toposiomerase enzymes that control DNA supercoiling as replicating stands separate

24
Q

Are fluoroquinolones broad or narrow spectrum

A

Broad

25
Q

Are fluoroquinolones bacteriocidal or bacteriostatic

A

Bacteriocidal

26
Q

What type of organism tends to be resistant to fluoroquinolones

A

Anaerobes

27
Q

What is enrofloxacin used for

A

Treatment of respiratory, dermal, and urinary tract infections (including prostatitis) in dogs, cats and birds and respiratory infections in cattle

28
Q

What is danofloxacin used for

A

Treatment of respiratory infections in cattle, including Mannheimia spp

29
Q

What is difloxacin used for

A

Treatment of dermal, respiratory and urinary tract infections in dogs

Good for Pasteurella

30
Q

What is orbifloxacin and marbofloxacin used for

A

Treatment of dermal, respiratory and urinary tract infections in dogs and cats

Orbifloxacin used for susceptible gram - infections in horses

31
Q

What is moxifloxacin used for

A

Anaerobic infections in small animals

32
Q

T or F: extra label use of fluoroquinolones in food producing animals is banned

A

True

33
Q

T or F: fluoroquinoles distribute to CNS, bone and prostate

A

True

34
Q

What is the mechanism of resistance for fluoroquinolones

A

Mutations in gene encoding DNA gyrase and toposiomerase

35
Q

What are some adverse effects of fluroquinolones

A
  1. Reversible erosion of articular cartilage in young foals and dogs particularly at high doses for longer than 14 days in rapid growth phase
  2. Enrofloxacin produces seizures in dogs on phenobarbital
  3. Retinal degeneration in cats
36
Q

What fluoroquinolones should not be used in dogs with seizures on phenobarbital

A

Enrofloxacin

37
Q

Which fluoroquinolones are least toxic

A

Orbifloxacin and marbofloxacin

38
Q

What is the mechanism of action of metronidazole

A

Taken up by anaerobic bacteria and Protozoa and reduced to cytotoxic metabolite which disrupts DNA

39
Q

Is metronidazole bacteriocidal or bacteriostatic and against what

A

Bacteriocidal against most obligate anaerobes and Protozoa like giardia and trichomonas

40
Q

T or F: you can use metronidazole in food producing animals

A

False-banned

41
Q

What is metronidazole used for

A
  1. Dogs, cats and horses in treatment of severe infections caused by anaerobic pathogens especially brain abscesses, pelvic, GU tract, and respiratory infections
  2. Protozoa infections like Giardia and Trichomoniasis
  3. Combined with clindamycin to prevent C. Difficicle induced pseudomembranous colitis
42
Q

What is the mechanism of action for rifampin

A

Inhibits DNA-dependent RNA polymerase which prevents initiation of RNA synthesis

43
Q

Is rifampin bacteriocidal or bacteriostatic and against what

A

Bacteriocidal against mycobacteria and gram + pathogens and intracellular infections

44
Q

What are the uses for rifampin

A
  1. Combined with erythromycin (or other macrolide) to tx R. equi in foals
  2. Combo with anti fungal agents to tx infections like aspergillosis or histoplasmosis in dogs and cats with CNS infections
45
Q

What are some adverse effects of rifampin

A

Hepatotoxicity
Red-orange urine, sweat, saliva

46
Q

What is the mechanism of action of nitrofurantoin

A

Reduced by bacteria to reactive intermediates that inhibit nucleic acid synthesis

47
Q

What is nitrofurantoin used for

A

Tx lower urinary tract infections in dogs and cats

48
Q

Nitrofurantoin is most effective in ___urine

A

Acidic

49
Q

Nitrofurazone is used topically as a ___

A

Antibacterial ointment powder or water-soluble wound dressing in all species

50
Q

T or F: you can use nitrofurans in food producing animals

A

False-banned