What is the recommended treatment for a urinary tract infection caused by Coagulase Negative Staph (CoNS) with a bacterial load of greater than or equal to 100,000 cells/ml, as detected by a PCR (Polymerase Chain Reaction) test, in a patient with a negative in-office urine test?

Treatment of Urinary Tract Infection with Coagulase Negative Staphylococci

For a urinary tract infection caused by Coagulase Negative Staphylococci (CoNS) with a bacterial load of ≥100,000 cells/ml detected by PCR but with a negative in-office urine test, treatment is generally not recommended unless you have symptoms of UTI, as this likely represents asymptomatic bacteriuria rather than true infection.

Understanding the Clinical Significance

• CoNS (particularly S. epidermidis) are commonly found as contaminants or colonizers rather than true pathogens in the urinary tract, especially in patients without symptoms 1
• The discrepancy between your negative in-office urine test and positive PCR test suggests this may be asymptomatic bacteriuria rather than a true infection 1
• Current guidelines specifically note that organisms such as coagulase-negative staphylococci are "not considered clinically relevant urine isolates" in many cases 1

When Treatment Should Be Considered

Treatment may be warranted in the following situations:

• If you have symptoms consistent with UTI (dysuria, frequency, urgency, suprapubic pain) 1
• If you have risk factors such as:
  • Indwelling urinary catheter 1
  • Recent urological procedure 1
  • Immunocompromised status 1
  • Pregnancy (asymptomatic bacteriuria should be treated in pregnant women) 1

Treatment Recommendations When Indicated

If treatment is deemed necessary based on symptoms or risk factors:

• First-line treatment options:

  • Nitrofurantoin for 5 days (for uncomplicated cystitis) 1
  • TMP/SMX for 3 days (for uncomplicated cystitis) 1
  • First-generation cephalosporin for 7 days (for pyelonephritis) 1

• For complicated UTI with systemic symptoms:

  • Amoxicillin plus an aminoglycoside 1
  • A second-generation cephalosporin plus an aminoglycoside 1
  • An intravenous third-generation cephalosporin 1

• Duration of therapy:

  • 3-5 days for uncomplicated cystitis 1
  • 7-14 days for complicated UTI or pyelonephritis 1

Special Considerations for CoNS

• CoNS isolates (except S. saprophyticus) often show high resistance rates to commonly used antibiotics 2, 3
• Approximately 53% of CoNS may be resistant to methicillin and 37.5% to ciprofloxacin 3
• Treatment should be guided by antimicrobial susceptibility testing when available 1
• S. saprophyticus is more likely to be a true pathogen in young, sexually active women 4, 5

Clinical Approach Algorithm

1. Assess for symptoms of UTI:

   • If asymptomatic and no risk factors → no treatment needed 1
   • If symptomatic → proceed to treatment 1

2. Evaluate for complicated vs. uncomplicated UTI:

   • Uncomplicated: healthy non-pregnant women with no structural/functional abnormalities 1
   • Complicated: men, pregnant women, catheterized patients, immunocompromised, or those with structural/functional abnormalities 1

3. Select antimicrobial therapy based on:

   • Local resistance patterns 1
   • Patient risk factors 1
   • Severity of symptoms 1
   • Antimicrobial susceptibility results when available 1

Common Pitfalls to Avoid

• Treating asymptomatic bacteriuria (except in pregnancy), which can lead to unnecessary antibiotic use and resistance 1
• Failing to distinguish between contamination/colonization and true infection 1
• Not considering that PCR tests detect bacterial DNA but cannot distinguish between viable and non-viable organisms 1
• Overlooking the possibility that CoNS may be resistant to commonly used antibiotics 2, 3