Treatment of Group B Streptococcus UTI in Male with Recent Ureteral Stent
Ampicillin 500 mg orally every 8 hours for 7 days is the recommended first-line treatment for this Group B Streptococcus urinary tract infection in a male patient with a recent stent placement. 1
Primary Treatment Recommendation
Ampicillin remains the gold standard for GBS UTIs, with a recommended dosing of 500 mg orally every 8 hours for 7 days in this complicated UTI scenario (male patient with indwelling hardware). 1
Amoxicillin 500 mg orally every 8 hours represents an equally effective alternative if ampicillin is unavailable. 1
The 7-day duration is appropriate given this is a complicated UTI in a male patient (where prostatitis cannot be excluded) with recent instrumentation. 1, 2
Critical Context: Stent-Associated Infection Risk
The presence of a ureteral stent placed two weeks ago significantly increases infection risk due to bacterial biofilm formation on the device, with up to 30% of stents showing bacterial colonization. 2, 3
E. coli typically dominates stent infections, but GBS represents a recognized uropathogen in males with instrumentation. 4, 3
The stent itself should be evaluated for potential removal or exchange if clinically feasible, as the main risk factor for persistent infection is the duration the device remains in place. 2
Alternative Options for Penicillin Allergy
For non-severe penicillin allergies: Cefazolin 2 g IV initial dose, then 1 g IV every 8 hours can be used. 1
For severe penicillin allergies: Clindamycin 300-450 mg orally every 6 hours is appropriate ONLY if antimicrobial susceptibility testing confirms the GBS isolate is clindamycin-susceptible. 1, 5
Clindamycin resistance in GBS is substantial (18-26% in recent studies), making susceptibility testing mandatory before use. 6, 7
Vancomycin should be reserved for severe infections with significant beta-lactam allergies or treatment failures. 1, 8
Important Clinical Pitfalls
Do NOT use fluoroquinolones as first-line therapy for GBS UTI - while commonly used for other uropathogens in stent infections, GBS requires beta-lactam coverage as the primary approach. 1, 2
Avoid empiric clindamycin without susceptibility data - the cMLSB resistance phenotype is present in 76% of resistant GBS strains, rendering clindamycin ineffective despite in vitro testing appearing susceptible in some cases. 7
Erythromycin and azithromycin should be avoided - resistance rates exceed 36-44% in GBS UTI isolates. 6, 7
Monitoring Requirements
Follow-up urine culture after treatment completion is recommended to ensure eradication, particularly given the presence of the ureteral stent. 1
Reassess the need for continued stent placement at the earliest appropriate time, as removal eliminates the primary nidus for recurrent infection. 2
If symptoms persist beyond 48-72 hours of appropriate therapy, consider imaging to evaluate for complications such as abscess formation or obstruction. 2