Management of Group B Streptococcus in Urine

Diagnosis and Treatment

Asymptomatic bacteriuria is defined as bacterial growth >10⁵ CFU/mL in two consecutive samples in women and >10⁵ CFU/mL in a single sample in men, according to the European Association of Urology (EAU) 1
Treatment is not recommended for non-pregnant adults with Group B Streptococcus (GBS) in urine and colony counts of 10-100 million CFU/L unless the patient is symptomatic, as this represents asymptomatic bacteriuria rather than a true UTI, as recommended by the EAU 1
The EAU recommends not treating asymptomatic bacteriuria in certain patient populations, including women without risk factors, patients with well-regulated diabetes, postmenopausal women, elderly institutionalized patients, patients with dysfunctional/reconstructed lower urinary tract, renal transplant recipients, patients before arthroplasty surgery, and patients with recurrent UTIs 1
The EAU recommends treating GBS bacteriuria in pregnant women, patients undergoing urological procedures breaching the mucosa, and symptomatic patients with signs of active UTI 1
Treating non-significant bacteriuria leads to unnecessary antibiotic use and promotes resistance, according to the EAU 1

Obtain at least 2 sets of blood cultures (aerobic and anaerobic) before starting antimicrobial therapy if no substantial delay (>45 min), as recommended by the Surviving Sepsis Campaign 2, 3
Evaluate patients with GBS bacteremia for signs of sepsis and assess for potential sources of infection, including skin/soft tissue, urinary tract, and pneumonia, as recommended by the IDSA and the CDC 4

Antimicrobial susceptibility testing should be performed on the GBS isolate to guide treatment decisions, according to the CDC 5
Antimicrobial susceptibility testing should be performed on all GBS isolates from penicillin-allergic patients at high risk for anaphylaxis, including assessment for inducible clindamycin resistance using the D-zone test, as recommended by the CDC 5

For uncomplicated Group B Streptococcus urinary tract infections, the American College of Microbiology recommends amoxicillin 500 mg orally every 8 hours for 7-10 days, with alternative options including Nitrofurantoin 100 mg PO every 6 hours and Cefazolin 1-2 g IV every 8 hours or oral cephalexin 500 mg every 6 hours for patients with non-severe penicillin allergy 6, 7
Fluoroquinolones can be considered as an alternative regimen if the patient is susceptible, and Fosfomycin 3 g PO single dose can be considered for uncomplicated cases if treatment fails 6, 7
The standard duration of therapy for uncomplicated cases is 7-10 days, according to the Society of Critical Care Medicine, with extended therapy recommended for slow clinical response, undrainable foci of infection, or immunologic deficiencies 3

For patients with Group B streptococcus (GBS) infection who are allergic to penicillin, cefazolin is the recommended first-line alternative for those without history of anaphylaxis, while clindamycin (if susceptible) or vancomycin should be used for those with high risk of anaphylaxis, as recommended by the CDC 5
If resistant to erythromycin but susceptible to clindamycin, clindamycin can be used only if testing for inducible clindamycin resistance is negative, as recommended by the CDC 5
If resistant to clindamycin or susceptibility unknown, vancomycin should be used, as recommended by the CDC 5

The recommended first-line treatment for pregnant women with Group B streptococcus colonization during labor is:

Antibiotic	Dosage
Penicillin G	5 million units IV initial dose, then 2.5-3.0 million units IV every 4 hours until delivery
Ampicillin	2 g IV initial dose, then 1 g IV every 4 hours until delivery
Cefazolin	2 g IV initial dose, then 1 g IV every 8 hours until delivery

Alternative regimens include Clindamycin and Vancomycin, with specific guidelines for use based on GBS susceptibility and resistance patterns, as recommended by the CDC 5
GBS bacteriuria in pregnancy requires both treatment at diagnosis and intrapartum prophylaxis, as recommended by the CDC 8

The CDC recommends intrapartum antibiotic prophylaxis (IAP) for women with a positive GBS vaginal-rectal screening culture, GBS bacteriuria during any trimester, or a previous infant with invasive GBS disease, as well as for women with unknown GBS status at labor onset and certain risk factors 5

Resistance to clindamycin has been reported in 3-15% of isolates, and resistance to erythromycin is higher (7-25%), according to the CDC 8
Erythromycin is no longer an acceptable alternative for intrapartum GBS prophylaxis, as stated by the CDC 5
Continue breastfeeding even in the presence of maternal bacterial infections, and reinforce proper hygiene practices to minimize contamination of expressed breast milk, based on general principles of lactation and infection control 9