Antibiotics Overview Quiz

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Questions and Answers

What is the primary mechanism of action for bacitracin?

Inhibition of bacterial folate synthesis

Inhibition of bacterial DNA-gyrase

Interference with bacterial protein synthesis

Disruption of bacterial cell wall synthesis (correct)

Which of the following is NOT a common use for Bacitracin?

Feed additive

Intravenous administration (correct)

Ophthalmic use

Topical application

Which antibiotic is often found in combination with Bacitracin in topical creams?

Penicillin

Neomycin (correct)

Amoxicillin

Cephalexin

What is a potential adverse effect associated with Bacitracin use?

Nephrotoxicity (C) Signup and view all the answers

What is the class of antibiotic that Vancomycin belongs to?

Glycopeptides (D) Signup and view all the answers

Which of the following is a characteristic of Vancomycin?

Disruption of bacterial cell wall synthesis (D) Signup and view all the answers

What is a potential concern regarding the use of Vancomycin?

It can cause chelation with certain minerals (C) Signup and view all the answers

Why is oral administration of Vancomycin sometimes preferred?

It avoids the risk of intravenous injection complications (A) Signup and view all the answers

What is a common symptom associated with keratoconjunctivitis sicca induced by sulfonamides?

Crusting and mucoid discharge around the eyes (B) Signup and view all the answers

Which condition is a side effect of sulfonamides due to their interference with folic acid?

Hemolytic anemia (B) Signup and view all the answers

What is the primary reason nitrofurans may not achieve therapeutic levels in tissues?

Rapid renal elimination (C) Signup and view all the answers

What do sulfonamides block in order to cause blood dyscrasias?

PABA at two sites (D) Signup and view all the answers

Which of the following nitrofurans is primarily used as a soluble dressing?

Nitrofurazone (D) Signup and view all the answers

Which fluoroquinolone antibiotic is associated with severe caution in young dogs?

Enrofloxacin (C) Signup and view all the answers

What is the primary mechanism of action for fluoroquinolones?

Interfere with DNA metabolism (C) Signup and view all the answers

What is the withdrawal time for cattle treated with fluoroquinolones?

28 days (A) Signup and view all the answers

Which of the following drugs is considered a potentiated sulfonamide?

Sulfadimethoxine (C) Signup and view all the answers

What condition can result from the presence of sulfonamides in urine at a low pH?

Crystalluria (A) Signup and view all the answers

Which fluoroquinolone was noted for its effectiveness against pneumonia due to early use?

Enrofloxacin (D) Signup and view all the answers

What is illegal regarding the use of fluoroquinolones in animals?

Extra label use in food-producing animals (D) Signup and view all the answers

What adverse effect is associated with sulfonamides, besides crystalluria?

Anaemia (C) Signup and view all the answers

Study Notes

Antibiotics

Bacitracin
- Disrupts bacterial cell walls, similar to penicillins and cephalosporins, but via a different mechanism
- A polypeptide antibiotic (long chains of amino acids)
- Not susceptible to beta-lactamase
- Primarily targets gram-positive bacteria
- Primarily used topically, ophthalmically, and as a feed additive (poorly absorbed)
- Often found in combination preparations (e.g., with neomycin and polymyxin B)
- Toxic to the kidneys
Fluoroquinolones
- Inhibits bacterial enzyme DNA gyrase
- Broad-spectrum, effective against Salmonella and Pseudomonas
- Well absorbed into tissues and fluids
- Excreted in kidneys or bile
- High therapeutic index
- Not recommended for use in young animals
- May chelate with aluminum, iron, calcium, and zinc
- Do not administer with sucralfate
- Flexible dosing based on bacterial sensitivity and drug penetration
- Exhibits a "post-antibiotic effect"
- Available in various forms (e.g., injectable, oral suspensions, ophthalmic solutions)
Sulphonamides & Potentiatiated Sulphonamides
- Interfere with DNA metabolism (bacteriostatic)
- Were some of the first antibiotics used widely
- Initially excellent for treating pneumonia
- Resistance is now a concern due to widespread use
- Can be administered orally, parenterally, and topically
- Readily enter CSF (treatment for meningitis)
- Potentiating compounds (combined with other compounds to become bactericidal instead of bacteriostatic)
- Examples: Tribrissen (sulfadiazine), Trimidox (sulfadoxine), Borgal (sulfadoxine)
  - Often co-combined with other compounds like trimethoprim or ormetoprim (5:1 ratio).
  - Common examples include sulfamethoxazole/trimethoprim and sulfadiazine/trimethoprim
Nitrofurans
- Broad-spectrum bacteriostatic
- Less potent than traditional antibiotics
- Rapidly eliminated by the kidneys, often does not reach therapeutic levels in tissues
- Half of the drug is unchanged when secreted, thus typically used for urinary tract infections.
- Examples: Topazone (furazolidone), Equifur (nitrofurantoine), Furacin (nitrofurazone)

Precautions

Bacitracin: Toxic to the kidneys
Sulfonamides:
- Crystalluria (precipitation in urine) can occur if urine pH is too low
  - Prevention: increase urine volume and/or alkalinize urine. Do not overdose.
- Keratoconjunctivitis sicca (KCS)
- Blood dyscrasias (issues with blood cells, such as hemolytic anemia, thrombocytopenia, and agranulocytosis) are possible side effects.

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Description

Test your knowledge on the mechanisms and uses of various antibiotics, including Bacitracin and Fluoroquinolones. This quiz covers their effects, applications, and potential side effects for a comprehensive understanding of antibiotic therapy.