Antibiotics in Ophthalmology

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Questions and Answers

Which antibiotic is known to inhibit bacterial DNA gyrase?

Ciprofloxacin (correct)

Bacitracin

Azithromycin

Tobramycin

What is a common consideration for prescribing antibiotics in children?

Broad spectrum antibiotics are avoided.

Antibiotics are generally ineffective in children.

Routine culturing is always performed.

Cost can be a factor in choosing antibiotics. (correct)

Which of the following antibiotics is approved for use in infants 2 months and older?

Gentamicin

Moxifloxacin

Ciprofloxacin

Tobramycin (correct)

What is the mechanism of action of macrolides?

Inhibits protein synthesis by targeting the 50S ribosome Signup and view all the answers

Which antibiotic combination is known for its dual action of disrupting membrane integrity and inhibiting folic acid synthesis?

Polytrim Signup and view all the answers

Which antibiotic is most commonly prescribed for skin infections?

Mupirocin Signup and view all the answers

Which antibiotic is approved use for all ages?

Moxifloxacin Signup and view all the answers

Why is Neomycin primarily used in combination with other medications?

It can cause toxicity if used alone. Signup and view all the answers

What is the common cause of orbital cellulitis in children under 5 years of age?

Ethmoidal sinusitis Signup and view all the answers

Which antibiotic should be avoided in children under 8 years of age due to potential side effects?

Tetracycline Signup and view all the answers

Which bacteria are primarily responsible for preseptal or orbital cellulitis?

Staphylococcus aureus and Streptococcus Signup and view all the answers

What is the initial treatment of choice for preseptal cellulitis in children?

Oral antibiotics like Amoxicillin + Clavulanate Signup and view all the answers

When is hospitalization and IV antibiotics indicated for treatment of orbital cellulitis?

In severe cases or for children under 5 years Signup and view all the answers

Which of the following antibiotics can be prescribed if a patient has a penicillin allergy?

Azithromycin Signup and view all the answers

What role do nasal decongestants play in the treatment of sinusitis-related conditions?

They are primarily used for reducing congestion if sinusitis is present Signup and view all the answers

What is the best empirical treatment approach for preseptal cellulitis when the pathogen is not identified?

Oral antibiotics Signup and view all the answers

Which condition is commonly associated with in preseptal cellulitis?

Dacryocystitis Signup and view all the answers

Which sinus is well developed at birth and is most commonly associated with orbital cellulitis in young children?

Ethmoidal sinus Signup and view all the answers

Study Notes

Antibiotic Uses and Considerations

Indicated for bacterial conjunctivitis, corneal ulcers, corneal abrasions, and conjunctivitis due to nasolacrimal duct obstruction.
Culturing not routinely performed in children; broad-spectrum antibiotics are preferred.
Long-acting formulations available, with consideration for cost-effectiveness.

Antibiotic Mechanisms of Action (MOA)

DNA Gyrase Inhibition: Critical for bacterial DNA synthesis.
Protein Synthesis Inhibition: Targeting 30S and 50S ribosomal subunits.

Antibiotic Types and Examples

Fluoroquinolones:
- Ciloxan (Ciprofloxacin 0.3%): >2 years, cost-effective.
- Ocuflox (Ofloxacin 0.3%): >1 year.
- Quixin (Levofloxacin 0.5%): >6 years, rarely prescribed.
- Zymar (Gatifloxacin 0.3%): >1 year.
- Vigamox (Moxifloxacin 0.5%): Suitable for all ages.
- Moxeza (Moxifloxacin 0.5%): Approved for ≥4 months.
- Besivance (Besifloxacin 0.6%): >1 year.
Aminoglycosides:
- Tobrex (Tobramycin 0.3%): Solution and ointment; for infants ≥2 months often combined with other agents.
- Neomycin: Used only in combination treatments.
- Gentamicin: Approved for children ≥6 years.
Macrolides:
- Erythromycin: Available in ointment, oral, and IV forms; used for infants/newborns as a lubricating ointment.
- Azasite (Azithromycin 1%): ≥1 year, recommended for its twice-daily dosing but is expensive.
Combination Agents:
- Polytrim (Polymyxin B + Trimethoprim): Targets bacterial cell wall synthesis; approved for ≥2 months.
- Mupirocin: Used for skin infections.
- Sulfacetamide: Rarely utilized at 10% and 15% concentrations.

Oral Antibiotic Use in Children

Penicillins: Include Amoxicillin and Dicloxacillin; common allergy noted.
Cephalosporins: Similar to penicillins; examples include Cefazolin, Cefaclor, Ceftriaxone; also common allergies.
Macrolides: Example is Erythromycin.
Tetracyclines: Not prescribed for children under 8 years due to potential dental staining and growth delays.

Preseptal and Orbital Cellulitis

Preseptal cellulitis occurs when infection is superficial, while orbital cellulitis involves deeper tissues.
Ethmoidal sinusitis is the most common cause of orbital cellulitis (84-100% cases).
Traumatic skin breaches and infections like hordeolum or dacryocystitis lead to preseptal cellulitis.
Common pathogens: Staphylococcus aureus and Streptococcus spp.

Sinus Development

Ethmoid sinuses are present at birth; maxillary sinuses develop in the first two years.
Explained why ethmoidal sinusitis is prevalent in younger children.

Treatment Approaches

Antibiotics prescribed empirically, targeting common pathogens without prior identification.
Amoxicillin + Clavulanate (Augmentin) often prescribed at 250-500 mg PO TID or 875 mg PO BID.
Cephalexin (Keflex) is another treatment option at 250-500 mg PO TID.
Allergies to penicillin and sulfa monitored; alternatives include Azithromycin (Z-Pak) or Levofloxacin (500 mg PO).
Avoid tetracyclines in children under 8; hospitalization may be required for severe cases.

Additional Treatments

Nasal decongestants used if sinusitis is present.
Topical treatments like Polysporin or Erythromycin for conjunctivitis.
Surgical drainage indicated for abscesses.

Specific Antibiotics for Conditions

Internal Hordeolum: Amoxicillin/Clavulanate or Cephalexin.
Preseptal Cellulitis: Amoxicillin/Clavulanate or Sulfamethoxazole/Trimethoprim.
Dacryocystitis: Amoxicillin/Clavulanate or Sulfamethoxazole/Trimethoprim.
Canaliculitis: Typically treated with Cephalexin.
A cheat sheet for pediatric oral antibiotics is useful for quick reference.

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Description

This quiz covers antibiotic uses, mechanisms of action, and the types of antibiotics relevant for treating ocular infections. It highlights considerations for prescribing and offers examples of various antibiotic formulations. Test your knowledge on the essential aspects of antibiotic therapy in eye care.