What is the dosage and usage of second-generation cephalosporins (2nd gen cephalosporins) for treating bacterial infections?

Second-Generation Cephalosporins: Dosage and Usage for Bacterial Infections

Second-generation cephalosporins are effective broad-spectrum antibiotics with specific dosing regimens that vary by agent, infection type, and patient factors. These medications offer enhanced activity against β-lactamase–producing organisms compared to first-generation cephalosporins, making them valuable for treating various bacterial infections.

Common Second-Generation Cephalosporins and Standard Dosing

Oral Formulations:

• Cefuroxime axetil:

  • Standard adult dose: 250-500 mg PO twice daily 1
  • Duration: Typically 5-10 days depending on infection severity 2
  • For respiratory infections: 250 mg twice daily (mild) or 500 mg twice daily (more severe) 1
  • For uncomplicated UTIs: 125-250 mg twice daily 3

• Cefaclor:

  • Standard adult dose: 500 mg PO three times daily 4
  • Note: Has inadequate activity against some β-lactamase–producing organisms and higher risk of serum sickness-like reactions 4

• Cefprozil:

  • Standard adult dose: 500 mg PO every 12 hours 4
  • Good activity against β-lactamase–producing H. influenzae, M. catarrhalis, and S. aureus 4

Parenteral Formulations:

• Cefuroxime (IV/IM):

  • Standard adult dose: 750 mg to 1.5 grams IV/IM every 8 hours 2
  • For severe infections: 1.5 grams every 8 hours 2
  • For bone/joint infections: 1.5 grams every 8 hours 2
  • For life-threatening infections: 1.5 grams every 6 hours may be required 2

• Cefoxitin:

  • Standard adult dose: 1-2 g IV every 8 hours 4
  • Has anaerobic coverage, making it useful for mixed infections 4

Specific Clinical Applications

Respiratory Tract Infections

• For sinusitis and respiratory infections, second-generation cephalosporins offer advantages of twice-daily administration and enhanced activity against β-lactamase–producing organisms 4
• Cefuroxime is particularly effective against common respiratory pathogens including H. influenzae, S. pneumoniae, and M. catarrhalis 1
• For pneumonia, cefuroxime 1.5 g IV every 8 hours is recommended 4

Skin and Soft Tissue Infections

• For animal bites: Cefuroxime 500 mg PO twice daily or cefoxitin 1 g IV every 6-8 hours 4
• For diabetic foot infections (moderate severity): Cefoxitin can be used as a second-generation cephalosporin with anaerobic coverage 4

Urinary Tract Infections

• Most second-generation cephalosporins achieve high urinary concentrations (>1000 mg/L) 3
• For uncomplicated UTIs: Cefuroxime axetil 125-250 mg twice daily 3
• For complicated UTIs: Parenteral therapy may be required with cefuroxime 750 mg IV every 8 hours 2

Surgical Prophylaxis

• For clean-contaminated procedures: Cefuroxime 1.5 g IV approximately 30-60 minutes before incision 2
• For prolonged procedures: Additional 750 mg IV/IM every 8 hours 2
• For open heart surgery: 1.5 g IV at anesthesia induction and every 12 hours thereafter for a total of 6 doses 2

Dosage Adjustments for Special Populations

Renal Impairment

For cefuroxime 2:

• CrCl >20 mL/min: Standard dosing (750 mg-1.5 g every 8 hours)
• CrCl 10-20 mL/min: 750 mg every 12 hours
• CrCl <10 mL/min: 750 mg every 24 hours
• Hemodialysis patients: Additional dose after dialysis

Pediatric Dosing

• For children >3 months: Cefuroxime 50-100 mg/kg/day in divided doses every 6-8 hours 2
• For severe infections: 100 mg/kg/day (not exceeding maximum adult dose) 2
• For bone/joint infections: 150 mg/kg/day in divided doses every 8 hours 2
• For bacterial meningitis: 200-240 mg/kg/day IV in divided doses every 6-8 hours 2

Important Clinical Considerations

• Second-generation cephalosporins have better gram-negative coverage than first-generation agents but may have slightly reduced activity against gram-positive organisms 5
• Cefuroxime has excellent activity against β-lactamase-producing H. influenzae, making it particularly valuable for respiratory infections 6
• First-generation cephalosporins (like cephalexin) have poor coverage for H. influenzae and are therefore inappropriate for respiratory infections 4
• When treating suspected bacterial meningitis, third-generation cephalosporins are preferred over second-generation agents 4
• For empiric therapy, consider local resistance patterns, particularly for S. pneumoniae and H. influenzae 4

Common Adverse Effects

• Generally mild and transient in nature 1
• Gastrointestinal disturbances (diarrhea, nausea, vomiting) most common 1
• Cefaclor has higher risk of serum sickness-like reactions compared to other second-generation cephalosporins 4

Contraindications

• Known hypersensitivity to cephalosporins 2
• Caution in patients with penicillin allergy due to potential cross-reactivity 2

Second-generation cephalosporins represent an important class of antibiotics with a balance of gram-positive and gram-negative coverage, making them valuable for treating various community-acquired infections while maintaining a favorable safety profile.