Is treatment necessary for a patient with a urine culture positive for Staphylococcus (Staph) epidermidis?

Treatment of Staphylococcus epidermidis Bacteriuria

In most cases, Staphylococcus epidermidis isolated from urine culture should NOT be treated, as it typically represents contamination from skin flora rather than true infection. 1

When Treatment is NOT Indicated

The Infectious Diseases Society of America explicitly recommends against treating asymptomatic bacteriuria with S. epidermidis in most populations, as treatment promotes antimicrobial resistance without providing clinical benefit. 1 This recommendation is based on the following considerations:

• S. epidermidis is normal skin flora and a common contaminant in urine cultures, particularly when proper collection technique is not followed. 1
• The Hospital Infection Control Practices Advisory Committee discourages treatment of single positive cultures when contamination is likely. 1
• Treating asymptomatic bacteriuria increases the risk of antimicrobial resistance, Clostridioides difficile infection, and unnecessary adverse drug events without improving patient outcomes. 2
• Studies show that 45% of asymptomatic bacteriuria cases are inappropriately treated, driven by overinterpretation of laboratory data. 2

When Treatment IS Indicated

Treatment should be initiated only in specific clinical scenarios:

Symptomatic Urinary Tract Infection

• Treat when the patient has clear urinary symptoms (dysuria, frequency, urgency, suprapubic pain) AND a positive culture for S. epidermidis. 1
• The American Academy of Pediatrics recognizes that S. epidermidis can cause true UTIs in children with anatomic abnormalities, though it should not be treated as a first-line pathogen without clear clinical indication. 1, 3

Before Urologic Procedures

• The Infectious Diseases Society of America recommends treating S. epidermidis urinary tract infections in patients undergoing endoscopic urologic procedures with anticipated mucosal trauma. 1
• This prevents procedure-related complications and bacteremia. 4

Pregnancy

• The Infectious Diseases Society of America recommends treating asymptomatic bacteriuria in pregnant women, one of the few populations where asymptomatic bacteriuria requires treatment. 1
• This is consistent with European Association of Urology guidelines recommending screening and treatment in pregnancy. 5

Device-Related Infections

• Device removal is often necessary for device-related infections, as S. epidermidis produces extracellular slime forming biofilms on indwelling devices, requiring higher antibiotic concentrations to eradicate. 1, 6
• Most S. epidermidis infections are hospital-acquired and involve indwelling foreign devices. 6

Clinical Decision Algorithm

Step 1: Assess for symptoms

• If asymptomatic → Do NOT treat (unless pregnant or pre-urologic procedure). 1
• If symptomatic (dysuria, frequency, urgency, fever) → Proceed to Step 2. 1

Step 2: Evaluate for contamination

• Single positive culture with low colony count → Likely contamination, do not treat. 1
• Proper specimen collection technique is essential to minimize contamination. 1

Step 3: Check for special circumstances

• Pregnancy → Treat. 1
• Planned urologic procedure with mucosal trauma → Treat. 1
• Indwelling urinary catheter or device → Consider device removal plus treatment. 1, 6
• Anatomic urinary abnormalities or nephrolithiasis → Consider treatment if symptomatic. 3, 4

Step 4: If treatment indicated

• Vancomycin is the drug of choice for methicillin-resistant strains (common in nosocomial infections). 6
• For methicillin-sensitive strains, use penicillinase-resistant penicillins or cephalosporins. 6
• Consider combination therapy (vancomycin plus rifampin or gentamicin) for serious infections. 6

Common Pitfalls to Avoid

• Do not treat based solely on pyuria or positive nitrites without symptoms, as this drives inappropriate antibiotic use. 2
• Do not assume all positive cultures represent infection – S. epidermidis is frequently a contaminant. 1, 6
• Do not use vancomycin for routine prophylaxis of catheter-associated infections or for treating presumed infections when cultures are negative. 1
• Do not overlook the possibility of bacteremic seeding in patients with nephrolithiasis or recent instrumentation who have both positive urine and blood cultures. 4