Treatment Approach for Coagulase-Negative Staphylococcus in Urine Culture
For a single positive urine culture showing coagulase-negative Staphylococcus (CoNS), treatment is generally not recommended as this likely represents contamination rather than true infection, unless there are specific clinical indicators of urinary tract infection.
Determining Clinical Significance
When evaluating CoNS in urine culture, consider:
Signs of True Infection vs. Contamination
- Single positive culture: Most likely represents contamination 1
- Multiple positive cultures: May indicate true infection, especially with consistent organism identification 1
- Colony count: Higher counts are more concerning for infection
- Presence of pyuria: Supports true infection rather than contamination 1
Clinical Context Requiring Treatment
- Symptomatic patient (dysuria, frequency, urgency)
- Fever without other source
- Suprapubic tenderness
- Presence of indwelling catheter with symptoms 1, 2
- Immunocompromised status
Species Considerations
Different CoNS species have different clinical significance:
S. saprophyticus: True urinary pathogen, especially in young women with acute uncomplicated cystitis 3
- Requires treatment when isolated in significant numbers with symptoms
- Generally more antibiotic-sensitive than other CoNS 2
S. epidermidis: Often associated with catheterized patients and complicated UTIs 2
- Higher rates of antibiotic resistance
- More likely to represent contamination in non-catheterized patients
Treatment Recommendations
When Treatment is Indicated:
First-line options:
For methicillin-resistant strains (14-67% of isolates):
Duration of therapy:
- Uncomplicated UTI: 5-7 days
- Complicated UTI: 10-14 days 1
When NOT to Treat:
- Single positive culture with CoNS (except S. saprophyticus) without symptoms 1
- Low colony count without pyuria
- Multiple negative cultures after initial positive
Important Caveats
Avoid unnecessary vancomycin use: The HICPAC guidelines specifically discourage vancomycin use "in response to a single blood culture positive for coagulase-negative staphylococcus, if other blood cultures taken during the same time frame are negative" 1. This principle applies to urine cultures as well.
Catheter considerations: For catheter-associated infections with CoNS, catheter removal is preferred when feasible 1. If the catheter must remain, antibiotic lock therapy in addition to systemic antibiotics may be considered.
Antimicrobial resistance: CoNS have increasing rates of resistance to multiple antibiotics 7. Susceptibility testing should guide therapy.
Differentiate colonization from infection: Particularly important in catheterized patients where CoNS colonization is common 1.
Follow-up
- Repeat urine culture after treatment completion if symptoms persist
- Consider urologic evaluation for recurrent infections
- For catheterized patients with recurrent CoNS infections, evaluate for catheter removal or replacement