Treatment of Group B Streptococcus (Strep B) UTI in Men
For Group B streptococcus urinary tract infections in men, treat with ampicillin 500 mg orally four times daily for 14 days, as all male UTIs are classified as complicated infections requiring extended therapy to exclude prostatitis. 1, 2, 3
Antibiotic Selection
First-Line Treatment
- Ampicillin is the drug of choice for Group B streptococcus (Streptococcus agalactiae) UTI, with documented successful outcomes in male patients 4
- The FDA-approved dosing for genitourinary tract infections is 500 mg orally four times daily in equally spaced doses 3
- Ampicillin should be administered at least 30 minutes before or 2 hours after meals for maximal absorption 3
Alternative Options
- Penicillin V potassium can be considered as an alternative beta-lactam option, though ampicillin has better documented efficacy for GBS UTI 5, 4
- Clindamycin (150-300 mg every 6 hours for serious infections) may be used in patients with penicillin allergy 6
Avoid These Agents
- Do not use trimethoprim-sulfamethoxazole for prolonged treatment of Streptococcus faecalis (enterococcus) infections, as resistance develops with extended use beyond 2 weeks, though this is less relevant for GBS 7
- Fluoroquinolones should not be used empirically if the patient has used them in the last 6 months or if local resistance rates exceed 10% 1, 2
Treatment Duration
Standard Approach
- Treat for 14 days when prostatitis cannot be excluded, which applies to essentially all male UTIs given the anatomical considerations 1, 2
- This extended duration is necessary because male UTIs are classified as complicated infections with broader microbial spectrum and higher resistance likelihood 1, 2
Shortened Duration Considerations
- A 7-day course may be considered only when the patient is hemodynamically stable and has been afebrile for at least 48 hours 1, 2
- However, given that GBS can cause persistent infection, the full 14-day course is prudent 4
Essential Diagnostic Steps
Pre-Treatment
- Always obtain urine culture and susceptibility testing before initiating therapy to confirm GBS and guide antibiotic selection 1, 2
- Evaluate for underlying urological abnormalities or complicating factors that may require management 2
Additional Considerations
- In males with GBS UTI, consider obtaining urethral specimens as GBS may colonize the urethra 4
- GBS isolated at ≥10^5 CFU/mL in midstream voided urine with clinical signs and pathologic urinary sediment confirms infection 4
Follow-Up and Monitoring
Post-Treatment Assessment
- Obtain follow-up cultures 7-14 days after completing therapy to ensure bacterial eradication 3
- Continue frequent bacteriologic and clinical appraisal during therapy, which may be necessary for several months in chronic infections 3
- Monitor for resolution of symptoms and consider imaging studies if recurrent infections occur to rule out anatomical abnormalities 1, 2
Treatment Failure
- If stubborn infections persist, treatment for several weeks may be required 3
- Therapy must be sufficient to eliminate the organism completely to prevent sequelae 5
Critical Pitfalls to Avoid
- Never treat male UTIs with short courses (3-5 days) designed for uncomplicated cystitis in women, as all male UTIs are complicated by definition 1, 2
- Do not fail to obtain urine culture before starting antibiotics, as this is essential for confirming GBS and guiding therapy 1, 2
- Do not overlook prostatitis, which requires the full 14-day treatment course and may need prolonged intensive therapy if complications develop 1, 2, 3
- Avoid inadequate dosing—smaller doses than recommended should not be used 3
- Do not ignore underlying urological abnormalities, as management of structural issues is mandatory alongside antibiotic therapy 2