Do you treat a symptomatic patient with 10,000 to 25,000 colony forming units (CFU) of beta-hemolytic streptococcus group B in a urine culture?

Treatment of Symptomatic Group B Streptococcus Bacteriuria

Yes, treat symptomatic patients with 10,000-25,000 CFU/mL of Group B Streptococcus (GBS) in urine culture according to current standards of care for urinary tract infection. 1

Key Diagnostic Considerations

The colony count threshold you describe (10,000-25,000 CFU/mL) falls below the traditional 100,000 CFU/mL cutoff, but this should not prevent treatment in symptomatic patients:

• In symptomatic patients, even growth as low as 10² CFU/mL (100 CFU/mL) could reflect true infection 2
• The historical 100,000 CFU/mL threshold is increasingly recognized as too rigid; lower CFU counts can indicate significant infections in symptomatic patients 1
• For catheterized specimens, the diagnostic threshold is ≥50,000 CFU/mL, but this must be interpreted with clinical symptoms and urinalysis results 1, 3

Clinical Context for GBS in Urine

GBS bacteriuria has distinct clinical significance:

• Patients with GBS in urine (≥10⁵ CFU/mL) have the same incidence of acute lower urinary tract symptoms as those with E. coli, and significantly more symptoms than those with negative cultures 4
• However, fever is less common with GBS compared to E. coli urinary infections 4
• Urinary tract abnormalities are most common in patients with GBS bacteriuria, suggesting underlying structural issues 4

Treatment Approach

For Symptomatic Patients:

Treat according to standard UTI protocols when the patient has urinary symptoms (dysuria, urgency, frequency) plus evidence of pyuria and/or bacteriuria on urinalysis 1, 3:

• The presence of symptoms combined with positive urinalysis (leukocyte esterase, nitrites, WBCs, or bacteria on microscopy) supports treatment 1, 3
• Bacteriuria is more specific and sensitive than pyuria for detecting UTI 2
• Treatment should use β-lactam antibiotics as the cornerstone of therapy for GBS infections 5

Special Populations:

Pregnancy: Any GBS bacteriuria in pregnancy warrants treatment regardless of colony count or symptoms:

• Women with symptomatic or asymptomatic GBS urinary tract infection detected during pregnancy should be treated according to current standards 1
• This is independent of the colony count 6
• Prenatal culture-based screening at 35-37 weeks is not necessary for women with documented GBS bacteriuria 1

Critical Pitfalls to Avoid

Do Not Confuse with Asymptomatic Bacteriuria:

• If the patient is truly asymptomatic (no urinary symptoms), do not treat 1
• Treating asymptomatic bacteriuria may be harmful and contributes to antimicrobial resistance, adverse drug effects, and C. difficile infection 1
• The exception is pregnancy, where all GBS bacteriuria requires treatment 1

Verify True Bacteriuria:

• One-third of patients with ≥10⁵ CFU/mL GBS in voided urine may have contamination only, not true bacteriuria 4
• If clinical suspicion is low despite positive culture, consider repeat specimen via catheterization 4
• Specimens from collection bags cannot be used for definitive diagnosis and require confirmation 1, 3

Laboratory Reporting Standards:

• Laboratories should report GBS in urine when present at concentrations ≥10⁴ CFU/mL (10,000 CFU/mL) in pure culture or mixed with a second microorganism 1
• Your colony count of 10,000-25,000 CFU/mL meets this reporting threshold 1

Antimicrobial Selection

For non-pregnant patients with GBS UTI:

• β-lactam antibiotics (penicillin or ampicillin) are preferred 5
• For β-hemolytic streptococcal infections, treatment should continue for at least 10 days 7
• Consider local resistance patterns and patient allergies when selecting specific agents 1