Can Keflex Be Used for Concurrent Strep and UTI?
Yes, cephalexin (Keflex) can effectively treat concurrent streptococcal infections and urinary tract infections, as it is FDA-approved for both indications and demonstrates excellent activity against the causative organisms.
FDA-Approved Indications
Cephalexin is specifically indicated for:
- Respiratory tract infections caused by Streptococcus pyogenes (Group A Strep), though penicillin remains the usual drug of choice for streptococcal infections 1
- Genitourinary tract infections caused by E. coli, Proteus mirabilis, and Klebsiella pneumoniae 1
- Skin and skin structure infections caused by Staphylococcus aureus and/or Streptococcus pyogenes 1
Practical Dosing Strategy
For treating concurrent infections:
- Standard dosing: 500 mg four times daily for 7-14 days depending on infection severity 1
- Alternative twice-daily dosing (500 mg BID) is equally effective for uncomplicated UTIs and may improve adherence 2
- For complicated UTIs in men where prostatitis cannot be excluded, extend treatment to 14 days 3
Clinical Effectiveness
The evidence supports cephalexin's dual utility:
- High urinary concentrations with full activity against common UTI pathogens 4
- Effective streptococcal eradication from infected sites, though it should not replace penicillin for rheumatic fever prophylaxis 1
- Treatment success rates demonstrate bacteriuria clearance in the majority of patients within 2 days 5
Important Caveats
Culture and susceptibility testing should be obtained before initiating therapy 1. This is critical because:
- Local resistance patterns vary and may affect empiric choices 3
- Streptococcal resistance to cephalosporins, while uncommon, can occur 3
- Tailoring therapy based on culture results optimizes outcomes 3
Do not use cephalexin if the patient has a history of anaphylaxis, angioedema, or urticaria to penicillins or cephalosporins due to potential cross-reactivity 3, 1.
When to Consider Alternatives
For complicated UTIs with systemic symptoms, European Association of Urology guidelines recommend:
- Second-generation cephalosporin plus aminoglycoside, or
- Intravenous third-generation cephalosporin as empirical treatment 3
These combinations provide broader coverage when dealing with more severe presentations or when multidrug-resistant organisms are suspected.