From the Research
Yes, alpha-hemolytic streptococci in a urine culture are likely contaminants. Alpha-hemolytic streptococci are typically not considered urinary pathogens. They are common inhabitants of the skin and mucous membranes, including the genital area. Their presence in a urine culture often indicates contamination during sample collection rather than a true urinary tract infection, as supported by the study on urine culture contamination 1. To confirm this:
- Check for symptoms of urinary tract infection (UTI).
- Look for other signs of infection in the urinalysis (e.g., elevated white blood cells, nitrites).
- Consider repeating the urine culture with a clean-catch midstream sample. If the patient is asymptomatic and the urinalysis is otherwise normal, no treatment is typically necessary. However, if there are symptoms of UTI or other concerning findings, further evaluation may be warranted to identify the true causative pathogen. The most recent study on the topic of urinary tract infections 2 highlights the importance of accurate identification of pathogens, but does not change the fact that alpha-hemolytic streptococci are generally considered contaminants in urine cultures. To reduce contamination in future samples:
- Provide clear instructions for proper clean-catch technique
- Consider catheterized specimens if clean-catch is difficult
- Ensure proper labeling and handling of specimens Understanding the normal flora of the urogenital area helps interpret urine culture results accurately and avoid unnecessary antibiotic use, as noted in the study on hemolytic activity and biofilm-formation among clinical isolates of group B streptococcus 3. It's also worth noting that while alpha-hemolytic streptococci can be pathogenic in certain contexts, such as in immunocompromised patients 4 or neonates 5, this is not typically the case in urinary tract infections.