Treatment of Streptococcal Bacteria in Urine
For streptococcal urinary tract infections, amoxicillin 500 mg orally every 8 hours for 5-7 days is the first-line treatment, achieving high clinical and microbiological eradication rates. 1, 2
Antibiotic Selection by Streptococcal Species
Group B Streptococcus (Streptococcus agalactiae)
- Amoxicillin 500 mg orally every 8 hours for 5-7 days is the preferred first-line agent for uncomplicated UTIs 1
- Amoxicillin-clavulanic acid 875/125 mg orally twice daily provides broader coverage if mixed infection is suspected 1
- For hospitalized patients with systemic involvement, IV penicillin G (2-4 million units every 4-6 hours) plus clindamycin (600-900 mg every 8 hours) may be considered 1
- Ampicillin is an equivalent alternative to amoxicillin at the same dosing (500 mg every 8 hours for 7 days) 1, 3
Enterococcus faecalis
- Ampicillin/amoxicillin remains the drug of choice, with high-dose ampicillin (18-30 g IV daily in divided doses) or amoxicillin 500 mg orally every 8 hours for 7 days recommended 2, 4
- High urinary concentrations of ampicillin can overcome elevated MICs even when in vitro testing suggests resistance 2
- Nitrofurantoin 100 mg orally every 6 hours for 7 days is an effective alternative with low resistance rates (below 6%) 2, 5
- Fosfomycin 3 g orally as a single dose is FDA-approved specifically for E. faecalis UTI and recommended for uncomplicated infections 2, 5
Penicillin-Susceptible Oral Streptococci
- For penicillin-susceptible strains (MIC ≤0.125 mg/L), penicillin G 12-18 million units/day IV in divided doses for 4 weeks is standard for serious infections like endocarditis 6
- For uncomplicated UTIs, shorter courses of 5-7 days with oral amoxicillin are appropriate 1
- Ceftriaxone given once daily is particularly convenient for outpatient therapy 6
Treatment Duration
- 5-7 days of therapy is typically sufficient for uncomplicated UTIs 1
- Longer courses (10-14 days) are necessary for complicated infections or those with systemic involvement 1
- For complicated UTIs in men, 7 days minimum is recommended, as all male UTIs are considered complicated 7
- Treatment should continue for a minimum of 48-72 hours beyond clinical improvement 4
Critical Clinical Considerations
Obtain Cultures Before Treatment
- Urine culture should be obtained before starting antibiotics when possible, especially in complicated or recurrent UTIs 1
- Always obtain susceptibility testing before initiating therapy, even for strains described as "pansensitive" 2
Differentiate Colonization from Infection
- Asymptomatic bacteriuria with streptococci does not routinely require treatment except in pregnant women and before urologic procedures with mucosal bleeding 2, 7
- Clinical improvement should be expected within 48-72 hours of initiating appropriate therapy 1
Avoid Common Pitfalls
- Fluoroquinolones should be avoided due to high resistance rates (46-47%) and unfavorable risk-benefit ratios for uncomplicated UTIs 2
- For beta-lactamase producing strains, replace amoxicillin with amoxicillin-clavulanate 2
- Patients with penicillin allergy can receive nitrofurantoin 100 mg orally every 6 hours for 7 days as an alternative 2
Special Populations
Patients with Underlying Conditions
- For patients with diabetes, immunocompromised states, or kidney disease, consider longer treatment durations (10-14 days) 1
- In renal impairment with GFR 10-30 mL/min, reduce amoxicillin to 500 mg or 250 mg every 12 hours 4
- In severe renal impairment with GFR <10 mL/min, reduce to 500 mg or 250 mg every 24 hours 4
Pregnant Women
- Asymptomatic bacteriuria should be systematically investigated and treated in pregnancy 7
- Nitrofurantoin, amoxicillin, amoxicillin-clavulanic acid, cephalexin, and trimethoprim-sulfamethoxazole are acceptable choices 7