What medications cover Strep B (Streptococcus group B) in urine?

Treatment of Group B Streptococcus in Urine

Pregnant Women

All pregnant women with GBS isolated from urine at any concentration during pregnancy must receive intrapartum antibiotic prophylaxis during labor, regardless of whether the bacteriuria is treated earlier in pregnancy. 1

Immediate Treatment of GBS Bacteriuria During Pregnancy

If symptomatic or asymptomatic GBS UTI is detected during pregnancy, treat immediately with one of the following oral regimens 2:

• Amoxicillin 500 mg three times daily for 3-7 days (first-line) 2
• Cephalexin 500 mg four times daily for 3-7 days 2
• Nitrofurantoin 100 mg twice daily for 5-7 days (avoid in late pregnancy) 2, 3

Intrapartum Antibiotic Prophylaxis (Required at Labor)

Even if GBS bacteriuria was treated earlier in pregnancy, intrapartum prophylaxis is still mandatory because antibiotics do not eliminate GBS from the genitourinary tract and recolonization is typical 4, 2. GBS bacteriuria indicates heavy genital tract colonization and significantly increases risk of early-onset neonatal disease 1, 2.

For patients without penicillin allergy 4, 2:

• Penicillin G 5 million units IV initial dose, then 2.5 million units IV every 4 hours until delivery (preferred agent due to narrow spectrum) 4, 2
• Ampicillin 2 g IV initial dose, then 1 g IV every 4 hours until delivery (acceptable alternative) 4

For patients with penicillin allergy (not at high risk for anaphylaxis) 4, 2:

• Cefazolin 2 g IV initial dose, then 1 g IV every 8 hours until delivery 4, 2

For patients with penicillin allergy at high risk for anaphylaxis 4, 1:

• Perform antimicrobial susceptibility testing on GBS isolates, as approximately 20% of GBS isolates are resistant to clindamycin 1
• If susceptible: Clindamycin 900 mg IV every 8 hours until delivery 4
• If resistant or susceptibility unknown: Vancomycin 1 g IV every 12 hours until delivery 4

Key Clinical Pearls for Pregnancy

• No additional GBS screening at 35-37 weeks is needed for women with documented GBS bacteriuria during the current pregnancy 1, 2
• Women with planned cesarean delivery before labor onset and before membrane rupture do not require GBS prophylaxis, even with positive GBS urine culture 2
• Antibiotics must be administered for ≥4 hours before delivery for optimal effectiveness in preventing vertical transmission 4
• Urine specimen labels from prenatal patients must clearly state pregnancy status to ensure proper laboratory processing 1

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Non-Pregnant Adults

Non-pregnant adults with GBS bacteriuria should be treated only if they are symptomatic or have underlying urinary tract abnormalities. 1, 5

Asymptomatic Bacteriuria (No Treatment Indicated)

If GBS is isolated from urine culture with normal urinalysis and the patient is asymptomatic, no antibiotic treatment is indicated 5. This represents asymptomatic bacteriuria that should not be treated according to IDSA guidelines 5. Treating asymptomatic bacteriuria leads to unnecessary antibiotic exposure, resistance development, and potential adverse drug effects without clinical benefit 5.

Symptomatic UTI Treatment

For symptomatic non-pregnant patients with GBS UTI, treat according to standard UTI protocols with one of the following 5:

• Penicillin G 500 mg orally every 6-8 hours for 7-10 days (preferred due to narrow spectrum) 5
• Ampicillin 500 mg orally every 8 hours for 7-10 days 5
• For penicillin-allergic patients: Clindamycin 300-450 mg orally every 8 hours (perform susceptibility testing before use due to increasing resistance) 5

Complicated UTI or Severe Presentations

For patients presenting with systemic symptoms or complicated UTI 5:

• Initial IV therapy with ampicillin 2 g IV every 4-6 hours, then transition to oral therapy once clinically stable 5
• Consider combination therapy with ampicillin plus an aminoglycoside for severe presentations 5
• For complicated infections or when prostatitis cannot be excluded in men, extend treatment to 14 days 5

Follow-up Considerations

Follow-up urine culture after treatment completion may be warranted to ensure eradication, especially in patients with recurrent UTIs 5.

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Laboratory Reporting Standards

Laboratories should report GBS in urine when present at concentrations ≥10⁴ CFU/mL in pure culture or mixed with a second organism for non-pregnant patients 1. For pregnant patients, laboratories should report GBS present at any concentration 4, 1.