Should I stop cephalexin (Cefalexin) and switch to Bactrim (sulfamethoxazole and trimethoprim) if paronychia worsens?

Management of Paronychia Worsening with Cephalexin

Yes, you should stop cephalexin and switch to Bactrim (sulfamethoxazole-trimethoprim) if paronychia is worsening despite treatment. 1, 2

Rationale for Antibiotic Switch

• Worsening paronychia on cephalexin suggests either resistant organisms or non-bacterial etiology that requires a different antimicrobial approach 2
• Secondary bacterial or mycological superinfections are present in up to 25% of paronychia cases, which may not respond to cephalexin 1
• Both gram-positive and gram-negative organisms have been implicated in paronychia, and Bactrim provides broader coverage than cephalexin 1, 3
• The Infectious Diseases Society of America includes sulfamethoxazole-trimethoprim as a recommended agent for skin and soft tissue infections, particularly when MRSA is suspected 1

Assessment Before Switching

• Obtain bacterial, viral, and fungal cultures to identify potential resistant organisms or non-bacterial causes of infection 1, 4
• Evaluate the severity of paronychia based on parameters including redness, edema, discharge, and granulation tissue 1
• Consider possible fixed-drug eruption to cephalexin as a rare cause of worsening symptoms 5

Treatment Algorithm

Step 1: Stop Cephalexin and Start Bactrim

• Discontinue cephalexin immediately 2
• Start Bactrim (sulfamethoxazole-trimethoprim) as it covers both gram-positive and gram-negative organisms 1

Step 2: Add Topical Therapy

• Apply topical povidone iodine 2% twice daily to the affected area 1, 2
• Consider adding high-potency topical corticosteroids to reduce inflammation 1, 6
• Implement antiseptic soaks with dilute vinegar (50:50 dilution) or povidone-iodine for 10-15 minutes twice daily 2, 6

Step 3: Evaluate for Drainage

• Assess for presence of abscess, which would mandate drainage 6, 7
• Options for drainage range from instrumentation with a hypodermic needle to wider incision with a scalpel depending on severity 6

Monitoring and Follow-up

• Reassess after 2 weeks of the new treatment regimen 1
• If no improvement is seen, consider:
  • Additional cultures to identify resistant organisms 4
  • Evaluation for non-infectious causes such as irritant dermatitis or drug reaction 3, 5
  • Referral to dermatology or hand surgery for further evaluation 2

Prevention of Recurrence

• Implement preventive measures including keeping hands dry and avoiding trauma to nails 1, 2
• Regular application of emollients to periungual tissues 1
• Wear protective gloves during activities involving water or chemicals 1, 2
• Ensure proper nail care: trim nails straight across and not too short 1

Special Considerations

• Antibiotic-resistant acute paronychia may be caused by viral or fungal infections that won't respond to antibacterial therapy 4
• Chronic paronychia represents an irritant dermatitis that requires addressing the underlying cause rather than just antibiotic therapy 6, 7
• Consider predisposing factors such as finger sucking, nail biting, or chemical exposures that may contribute to treatment failure 2, 4