Do you treat a urinary tract infection with 20-30,000 colony count of Staphylococcus simulans?

Management of Staphylococcus simulans in Urinary Tract Infections

Treatment is not indicated for a urinary tract infection with 20-30,000 colony count of Staphylococcus simulans unless the patient is symptomatic or has specific risk factors for complicated UTI. This recommendation aligns with current guidelines on the management of asymptomatic bacteriuria.

Interpretation of Colony Count

• Colony count of 20-30,000 CFU/mL falls below the traditional threshold of >100,000 CFU/mL used to define significant bacteriuria in asymptomatic patients 1
• More recent evidence suggests lower thresholds (10²-10⁴ CFU/mL) may be significant in symptomatic patients 2
• Staphylococcus simulans is not among the common uropathogens listed in the European Association of Urology guidelines, which typically include E. coli, Proteus spp., Klebsiella spp., Pseudomonas spp., Serratia spp., and Enterococcus spp. 1

Decision Algorithm for Treatment

Do NOT treat if:

1. Patient is asymptomatic (asymptomatic bacteriuria) 1
2. Patient has no risk factors for complicated UTI
3. Patient is not pregnant 1, 3
4. Patient is not undergoing urologic procedures breaching the mucosa 1

Consider treatment if:

1. Patient has symptoms of UTI (dysuria, frequency, urgency, suprapubic pain)
2. Patient has risk factors for complicated UTI, including:
   • Obstruction in the urinary tract
   • Foreign body presence
   • Incomplete voiding
   • Vesicoureteral reflux
   • Recent instrumentation
   • Male gender
   • Pregnancy
   • Diabetes mellitus
   • Immunosuppression 1

Rationale for Recommendation

The Infectious Diseases Society of America (IDSA) strongly recommends against screening for or treating asymptomatic bacteriuria in most patient populations 1. This recommendation is based on:

• Lack of evidence for clinical benefit
• Risk of antimicrobial resistance development
• Risk of adverse effects including C. difficile infection
• Potential elimination of protective bacterial colonization

Special Considerations

• Staphylococcus species are uncommon causes of UTI compared to gram-negative organisms
• S. saprophyticus is the most common staphylococcal species causing UTI, particularly in young women 4, 5
• Other staphylococcal species like S. haemolyticus and S. aureus have been documented in UTIs, but typically in specific clinical scenarios such as catheterization 6, 7
• S. simulans is not well-documented as a significant urinary pathogen in the literature

Pitfalls to Avoid

• Do not treat based solely on culture results without clinical correlation
• Do not assume all bacteria in urine represent infection rather than colonization
• Do not overlook risk factors that might classify a UTI as complicated, which would warrant treatment regardless of colony count
• Do not miss the opportunity to screen for structural abnormalities in patients with recurrent UTIs (≥3 episodes in 12 months) 1

If treatment is warranted based on symptoms or risk factors, antimicrobial selection should be guided by susceptibility testing and local resistance patterns as outlined in the European Association of Urology guidelines 1.