What is the recommended oral cephalosporin (first-generation cephalosporin) for treating mild to moderate bacterial infections?

Recommended Oral Cephalosporins for Mild to Moderate Bacterial Infections

Cephalexin is the recommended first-line oral first-generation cephalosporin for treating mild to moderate bacterial infections due to its well-established efficacy, safety profile, and cost-effectiveness.

First-Generation Cephalosporins: The Preferred Choice

First-generation cephalosporins are the most appropriate choice for most mild to moderate bacterial infections because:

• They have excellent activity against gram-positive bacteria, particularly Staphylococcus aureus and Streptococcus species 1
• They provide reliable coverage for common skin, soft tissue, and respiratory infections
• They have a narrower spectrum than later generations, reducing the risk of promoting antimicrobial resistance
• They are generally less expensive than newer generations 2

Specific First-Generation Options

1. Cephalexin:

   • FDA-approved for respiratory tract infections, otitis media, skin/skin structure infections, bone infections, and genitourinary tract infections 3
   • Standard adult dosing: 250-500 mg orally every 6 hours
   • Pediatric dosing: 25-50 mg/kg/day divided every 6 hours
   • Well-absorbed from the GI tract with high and sustained serum concentrations 4

2. Cefadroxil:

   • Similar spectrum to cephalexin but with longer half-life allowing for less frequent dosing
   • Can be administered once or twice daily instead of four times daily 5

Clinical Decision Algorithm

1. For skin and soft tissue infections:

   • Cephalexin is recommended for non-purulent cellulitis targeting β-hemolytic streptococci and methicillin-sensitive S. aureus 6
   • Standard duration: 5-10 days based on clinical response

2. For respiratory tract infections:

   • Cephalexin is effective for streptococcal pharyngitis in penicillin-allergic patients (non-anaphylactic) 4
   • Narrow-spectrum cephalosporins like cephalexin are preferred over broad-spectrum options 4
   • Standard duration: 10 days for streptococcal pharyngitis

3. For urinary tract infections:

   • Cephalexin is effective against common uropathogens including E. coli, Proteus mirabilis, and Klebsiella pneumoniae 3

Important Considerations

Penicillin Allergy

• Approximately 10% of penicillin-allergic patients may also be allergic to cephalosporins 4
• Cephalosporins should NOT be used in patients with history of anaphylaxis, angioedema, or urticaria with penicillins 4
• For patients with severe penicillin allergy, consider alternative agents like clindamycin or macrolides 4

Resistance Patterns

• First-generation cephalosporins remain effective against most community-acquired infections
• They are more susceptible to beta-lactamases produced by gram-negative bacteria compared to later generations 7
• Local resistance patterns should guide therapy decisions

When to Consider Second or Third-Generation Cephalosporins

• Reserve broader-spectrum cephalosporins for:
  • Documented resistance to first-generation agents
  • More severe infections requiring enhanced gram-negative coverage
  • Specific indications where superior efficacy has been demonstrated

Common Pitfalls to Avoid

1. Using unnecessarily broad-spectrum cephalosporins when first-generation agents would be effective
2. Prescribing cephalosporins to patients with severe penicillin allergy
3. Inadequate duration of therapy (particularly for streptococcal pharyngitis)
4. Failure to consider local resistance patterns

Conclusion

For most mild to moderate bacterial infections requiring oral cephalosporin therapy, cephalexin represents the optimal balance of efficacy, safety, and cost-effectiveness. Its well-established track record, favorable side effect profile, and appropriate spectrum of activity make it the preferred first-generation cephalosporin for outpatient management of common bacterial infections.