What is the recommended treatment for a non-pregnant patient with a symptomatic urinary tract infection (UTI) caused by Streptococcus agalactiae, with a colony count of 10,002 to 50,000 colonies per milliliter (mL)?

Treatment of Symptomatic UTI Caused by Streptococcus agalactiae in Non-Pregnant Patients

Treat this symptomatic urinary tract infection with antibiotics despite the colony count being below the traditional 100,000 CFU/mL threshold, as symptomatic infections with 10,000-50,000 CFU/mL represent true infection requiring treatment. 1, 2

Colony Count Interpretation

• The traditional 100,000 CFU/mL threshold was established for asymptomatic bacteriuria and pyelonephritis, not symptomatic cystitis. 2
• Approximately one-third of women with confirmed symptomatic UTIs grow only 10,000-10,000 CFU/mL, making this colony count clinically significant when symptoms are present. 2
• The presence of symptoms (dysuria, frequency, urgency, suprapubic pain) combined with pyuria and this colony count establishes the diagnosis of true infection. 1, 2

Antibiotic Selection for Streptococcus agalactiae

First-line treatment options include:

• Ampicillin or amoxicillin - S. agalactiae demonstrates >95% in vitro sensitivity to ampicillin, making it an excellent first-line choice. 3
• Amoxicillin-clavulanate (Augmentin) - Also shows >95% sensitivity and provides broader coverage. 3
• First-generation cephalosporins (cephalexin) - Demonstrate >95% sensitivity to cephalothin and related agents. 3

Alternative options if penicillin allergy:

• Erythromycin (>95% sensitivity) 3
• Clindamycin (>95% sensitivity as lincomycin) 3

Treatment Duration and Approach

• Administer 7 days of antibiotic therapy for symptomatic cystitis, as this represents standard treatment for uncomplicated UTI. 1, 4
• Obtain urine culture before initiating treatment to confirm the organism and guide therapy if initial treatment fails. 1
• Do NOT treat this as asymptomatic bacteriuria - the presence of symptoms fundamentally changes management from observation to active treatment. 1

Critical Considerations for S. agalactiae

Identify potential reservoirs of infection:

• In women, examine for vaginal colonization as S. agalactiae commonly colonizes the genital tract. 3, 5
• Consider gastrointestinal tract and urethral colonization as potential sources. 3
• In men, perform digital rectal examination to evaluate for prostate involvement. 1

Patient demographics matter:

• S. agalactiae UTI in non-pregnant adults occurs predominantly in women over 40 years old (77.7% of cases). 5
• Uncomplicated cystitis is the most common presentation (66.1% of cases), followed by complicated infection (19.1%). 5
• Pyuria is present in approximately 73% of cases, supporting the diagnosis. 5

Common Pitfalls to Avoid

• Do not dismiss this infection as insignificant based solely on colony count - symptomatic infections with 10,000-50,000 CFU/mL require treatment. 2
• Do not use nitrofurantoin or fosfomycin as first-line for S. agalactiae - while these are excellent for E. coli, beta-lactams show superior activity against streptococcal species. 3
• Do not treat repeatedly if asymptomatic bacteriuria recurs after successful treatment - this fosters antimicrobial resistance without clinical benefit. 1
• Avoid fluoroquinolones - while they may have activity, beta-lactams are preferred given excellent sensitivity patterns and narrower spectrum. 3

When to Investigate Further

Obtain imaging if:

• Symptoms persist despite appropriate antibiotic therapy. 1
• Patient has severe abdominal or pelvic pain, as rare cases of secondary abscess formation have been reported with S. agalactiae UTI. 6
• Patient has underlying diabetes or immunosuppression, as these increase risk of invasive infection. 6, 5

Perform cystoscopy if:

• Recurrent infections occur despite appropriate treatment. 1
• Hematuria persists after treatment. 1