What is the recommended treatment for Streptococcus agalactiae isolated from a urine culture in pregnant women, symptomatic non‑pregnant adults, and asymptomatic non‑pregnant adults (including pre‑procedure prophylaxis)?

Treatment of Group B Streptococcus in Urine Culture

Pregnant Women

All pregnant women with GBS isolated from urine at any concentration must receive immediate treatment of the UTI followed by mandatory intravenous antibiotic prophylaxis during labor, regardless of symptoms or colony count. 1, 2

Immediate UTI Treatment

• Treat the acute UTI according to standard pregnancy protocols using pregnancy-safe antibiotics based on susceptibility testing 2
• Critical caveat: Treating the UTI does NOT eliminate GBS colonization from the genitourinary tract—recolonization after oral antibiotics is typical, which is why intrapartum prophylaxis remains mandatory even if bacteriuria was treated earlier in pregnancy 2
• GBS bacteriuria at any concentration during pregnancy indicates heavy genital tract colonization and significantly increases the risk of early-onset neonatal GBS disease 1, 2

Intrapartum Prophylaxis Regimens (During Labor)

For women without penicillin allergy:

• Preferred: Penicillin G 5 million units IV initially, then 2.5-3.0 million units IV every 4 hours until delivery 2
• Alternative: Ampicillin 2 g IV initially, then 1 g IV every 4 hours until delivery 2

For women with penicillin allergy (not high-risk for anaphylaxis):

• Cefazolin 2 g IV initially, then 1 g IV every 8 hours until delivery 2

For women at high-risk for anaphylaxis (history of immediate hypersensitivity reactions, angioedema, urticaria, or asthma):

• Clindamycin 900 mg IV every 8 hours until delivery (if isolate confirmed susceptible to both clindamycin and erythromycin) 2
• Vancomycin 1 g IV every 12 hours until delivery (if resistant to clindamycin or susceptibility unknown) 2

Critical Timing

• Intrapartum prophylaxis must be administered ≥4 hours before delivery for maximum effectiveness 2
• When given ≥4 hours before delivery, prophylaxis is 78% effective in preventing early-onset neonatal GBS disease 2

Special Pregnancy Scenarios

• Preterm labor (<37 weeks): Administer GBS prophylaxis immediately at hospital admission; discontinue if patient is not in true labor 1, 2
• Preterm premature rupture of membranes (PPROM): Ampicillin 2 g IV once, followed by 1 g IV every 6 hours for at least 48 hours is adequate for both latency and GBS prophylaxis 1, 2

Documentation Requirements

• Women with GBS bacteriuria at any point during pregnancy should not be re-screened with vaginal-rectal cultures at 35-37 weeks—they are presumed GBS colonized and automatically qualify for intrapartum prophylaxis 2
• Ensure laboratory reports are communicated to both the anticipated site of delivery and the ordering provider 2

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Symptomatic Non-Pregnant Adults

Symptomatic non-pregnant patients with GBS UTI should receive standard antibiotic treatment for 7-10 days based on susceptibility testing. 3

First-Line Treatment Options

• Preferred: Penicillin G 500 mg orally every 6-8 hours for 7-10 days (narrow spectrum, universally susceptible) 3
• Alternative: Ampicillin 500 mg orally every 8 hours for 7-10 days 3

Penicillin-Allergic Patients

• Clindamycin 300-450 mg orally every 8 hours for 7-10 days 3
• Critical caveat: Perform susceptibility testing before using clindamycin due to increasing resistance (3-15% resistance rates) 2, 4

Complicated UTI or Severe Presentations

• Consider initial IV therapy with ampicillin 2 g IV every 4-6 hours, then transition to oral therapy once clinically stable 3
• For severe presentations, consider combination therapy with ampicillin plus an aminoglycoside 3
• Extend treatment to 14 days for complicated infections or when prostatitis cannot be excluded in men 3

Follow-up

• Follow-up urine culture after treatment completion may be warranted to ensure eradication, especially in patients with recurrent UTIs 3

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Asymptomatic Non-Pregnant Adults

Asymptomatic non-pregnant patients with GBS isolated from urine should NOT receive antibiotic treatment—this represents asymptomatic bacteriuria that does not require treatment. 3

Evidence Against Treatment

• The 2019 IDSA guidelines provide strong evidence against screening for or treating asymptomatic bacteriuria in non-pregnant populations 3
• This principle applies to GBS-specific asymptomatic bacteriuria regardless of colony count 3
• Treating asymptomatic bacteriuria leads to unnecessary antibiotic exposure, resistance development, and potential adverse drug effects without clinical benefit 3

When Treatment IS Indicated in Non-Pregnant Patients

Treatment is appropriate only if the patient has:

• Symptomatic UTI (dysuria, frequency, urgency, suprapubic pain) 3
• Abnormal urinalysis (pyuria, hematuria) 3
• Underlying urinary tract abnormalities 3
• Planned urologic procedure (pre-procedure prophylaxis) 3

Critical Distinction from Pregnancy

• The CDC guidelines mandate treatment of all GBS bacteriuria during pregnancy, but this does NOT apply to non-pregnant individuals 3
• This is a critical distinction that prevents inappropriate antibiotic use in non-pregnant patients 3

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Common Pitfalls to Avoid

• Never treat asymptomatic GBS colonization outside of pregnancy or the intrapartum period—oral or IV antibiotics given before labor are completely ineffective at eliminating GBS colonization and may cause antibiotic resistance 2
• Do not assume treating a UTI in pregnancy eliminates the need for intrapartum prophylaxis—this is a common and dangerous error 2
• Do not use oral antibiotics alone for GBS prophylaxis in pregnancy—they are inadequate 1
• Do not treat asymptomatic bacteriuria in non-pregnant patients—this leads to unnecessary antibiotic exposure without benefit 3