What are the first-line antibiotics for skin infections, eye infections, urinary tract infections (UTIs), and ear infections?

First-Line Antibiotics for Common Infections

For common infections, the first-line antibiotics are: cephalexin for skin infections, fluoroquinolones for eye infections, nitrofurantoin or trimethoprim-sulfamethoxazole for UTIs, and amoxicillin for ear infections.

Skin Infections

First-line Treatment

• Cephalexin 500 mg orally 3-4 times daily for 5-6 days 1
• Alternative: Amoxicillin-clavulanate 875/125 mg twice daily for 5-6 days 1

Treatment Based on Severity

1. Mild infections (without MRSA risk factors):

   • Cephalexin 500 mg orally 3-4 times daily for 5 days 1

2. Moderate infections (or MRSA risk factors):

   • Clindamycin 300-450 mg orally three times daily for 5-6 days 1

3. Severe infections:

   • Vancomycin plus piperacillin-tazobactam or imipenem/meropenem (IV) 1

Important Considerations

• Examine interdigital spaces to treat fissuring, scaling, or maceration 1
• Elevate affected limb to reduce swelling and promote healing 1
• For MRSA infections, consider clindamycin or trimethoprim-sulfamethoxazole 1
• For necrotizing fasciitis caused by group A streptococci, use clindamycin and penicillin 2

Eye Infections

First-line Treatment

• Fluoroquinolones (topical) - such as ciprofloxacin or moxifloxacin drops
• For bacterial conjunctivitis: Erythromycin or polymyxin B-trimethoprim ophthalmic solutions

Treatment Based on Type

1. Bacterial conjunctivitis:

   • Fluoroquinolone drops 1-2 drops every 2 hours while awake for 2 days, then 1-2 drops 4 times daily for 5 days

2. Keratitis:

   • Fluoroquinolone drops hourly for severe cases

Urinary Tract Infections (UTIs)

First-line Treatment

• Nitrofurantoin 100 mg twice daily for 5 days
• Trimethoprim-sulfamethoxazole DS twice daily for 3 days

Treatment Based on Type

1. Uncomplicated cystitis:

   • Nitrofurantoin 100 mg twice daily for 5 days
   • Alternative: Trimethoprim-sulfamethoxazole DS twice daily for 3 days

2. Complicated UTI:

   • Fluoroquinolones (e.g., ciprofloxacin 500 mg twice daily for 7 days)
   • Alternative: Amoxicillin-clavulanate 875/125 mg twice daily for 7-14 days

Ear Infections

First-line Treatment

• Amoxicillin 500-875 mg orally three times daily for 5-7 days 3
• For children: 20-45 mg/kg/day in divided doses every 8-12 hours 3

Treatment Based on Type

1. Acute otitis media:

   • Amoxicillin (high-dose): 80-90 mg/kg/day for children
   • Alternative: Amoxicillin-clavulanate if treatment failure or recurrence

2. Otitis externa:

   • Topical antibiotic drops containing neomycin, polymyxin B, and hydrocortisone
   • For severe cases: Fluoroquinolone ear drops

Common Pitfalls to Avoid

1. For skin infections:

   • Failure to examine interdigital spaces 1
   • Inadequate elevation of affected limb 1
   • Treating for too long (>5 days) unless improvement isn't seen 1
   • Not performing incision and drainage for abscesses 1

2. For all infections:

   • Not considering local resistance patterns
   • Unnecessary MRSA coverage in areas with low MRSA prevalence 1
   • Not adjusting therapy if no improvement after 72 hours 1
   • Using antibiotics for viral infections

Remember that these recommendations are general guidelines, and treatment should be adjusted based on local resistance patterns, patient allergies, and specific clinical circumstances.