Treatment of Group B Streptococcus UTI in Non-Pregnant Adults
For symptomatic non-pregnant adults with GBS UTI, treat with ampicillin 500 mg orally every 8 hours for 7-10 days, or amoxicillin 500 mg orally every 8 hours as an equally effective alternative. 1, 2
Critical Distinction: Symptomatic vs. Asymptomatic
Do NOT treat asymptomatic GBS bacteriuria in non-pregnant patients - this represents colonization that should not receive antibiotics, as treatment leads to unnecessary antibiotic exposure, resistance development, and adverse effects without clinical benefit. 1
The 2019 IDSA guidelines provide strong evidence against screening for or treating asymptomatic bacteriuria in non-pregnant populations, with this principle applying specifically to GBS-specific asymptomatic bacteriuria. 1
Treatment is only appropriate if the patient has symptomatic UTI (dysuria, frequency, urgency, suprapubic pain), abnormal urinalysis (pyuria, positive leukocyte esterase), or underlying urinary tract abnormalities. 1
First-Line Antibiotic Regimens
Penicillin G 500 mg orally every 6-8 hours for 7-10 days is the preferred agent due to its narrow spectrum of activity, as recommended by the CDC. 1
Ampicillin 500 mg orally every 8 hours for 7-10 days is an acceptable alternative to penicillin. 1, 2
Both agents maintain universal GBS susceptibility, though research from 1992-2004 showed all isolates were sensitive to penicillin and ampicillin in clinical studies. 3, 4
Penicillin-Allergic Patients
Clindamycin 300-450 mg orally every 8 hours is recommended for penicillin-allergic patients, but susceptibility testing must be performed before use due to increasing resistance rates (19% resistance reported in some studies). 1, 4
Cefazolin 2 g IV initially, then 1 g IV every 8 hours, or cephalexin as an oral alternative can be used for patients without high-risk penicillin allergy. 2
Avoid using clindamycin without susceptibility testing, as this risks treatment failure due to high resistance rates. 2
Treatment Duration Based on Severity
Uncomplicated UTI: 7-10 days of oral therapy is standard. 1, 2
Complicated UTI or when prostatitis cannot be excluded in men: 14 days of treatment is recommended. 1
Severe presentations with systemic symptoms: Consider initial IV therapy with ampicillin 2 g IV every 4-6 hours, then transition to oral therapy once clinically stable. 1
For severe infections or bacteremia, extend treatment to 10-14 days. 2
Special Considerations and Monitoring
Obtain urine culture before initiating therapy to confirm diagnosis and guide treatment decisions, with significant bacteriuria defined as ≥50,000 CFUs/mL. 2
Follow-up urine culture after treatment completion may be warranted to ensure eradication, especially in patients with recurrent UTIs. 1
GBS accounts for approximately 2% of positive urine cultures in non-pregnant adults, with 85% occurring in women and 95% having at least one underlying condition (urinary tract abnormalities in 60%, chronic renal failure in 27%). 3
Common Pitfalls to Avoid
Never treat asymptomatic bacteriuria in non-pregnant patients - this is the most critical error, as it provides no clinical benefit and promotes antibiotic resistance. 1
Underdosing or premature discontinuation leads to treatment failure and recurrence. 2
Using clindamycin without susceptibility testing risks treatment failure, as resistance rates can be as high as 19-23%. 2, 4
Confusing pregnancy and non-pregnancy management - all GBS bacteriuria in pregnancy requires treatment regardless of symptoms, but this does NOT apply to non-pregnant patients. 1