Is Streptococcus dysgalactiae a Common Cause of UTI?
No, Streptococcus dysgalactiae is not a common cause of urinary tract infection and is not recognized among the established uropathogens in current clinical guidelines.
Established UTI Pathogens
The most recent European Association of Urology guidelines (2024) clearly identify the common organisms causing complicated UTIs as E. coli, Proteus spp., Klebsiella spp., Pseudomonas spp., Serratia spp., and Enterococcus spp. 1. Notably absent from this list is Streptococcus dysgalactiae or any closely related species.
For uncomplicated UTIs, E. coli remains the dominant pathogen, with Staphylococcus saprophyticus accounting for approximately 10-30% of infections in young adult women 2. The microbial spectrum for complicated UTIs is broader than for uncomplicated infections, but still does not include S. dysgalactiae as a recognized common pathogen 1.
Gram-Positive Uropathogens: The Recognized Species
Among Gram-positive bacteria that do cause UTIs, the established pathogens include 3:
- Staphylococcus saprophyticus - particularly in young women
- Enterococcus faecalis - especially in complicated UTIs
- Streptococcus agalactiae (Group B Streptococcus) - documented in specific populations
Group B Streptococcus (S. agalactiae) as Context
While S. agalactiae (a different species from S. dysgalactiae) has been documented as a urinary pathogen, it still represents an uncommon cause of UTI. In adults treated in outpatient settings, S. agalactiae was found mainly in women over 40 years old and caused non-complicated UTI in approximately half of cases 4. A prospective study found GBS cultured from only 1.1% of consecutive urine samples, with serotypes V, Ia, and III being most common 5.
Clinical Implications
When S. dysgalactiae is isolated from urine, consider it a potential contaminant or colonizer rather than a pathogen unless there is:
- Significant colony count (≥10^5 CFU/mL) 1
- Accompanying pyuria 4
- Compatible clinical symptoms
- Absence of other recognized uropathogens
The literature on emerging and underreported Gram-positive uropathogens mentions Aerococcus, Corynebacterium, Actinobaculum, and Gardnerella, but does not include S. dysgalactiae among these emerging pathogens 3.
Key Pitfall to Avoid
Do not automatically treat S. dysgalactiae isolated from urine as a pathogen requiring antimicrobial therapy. The organism is not among recognized common uropathogens in any major guideline 1, 6, and treatment may represent unnecessary antibiotic use unless clear evidence of true infection exists with this specific organism as the sole isolate.