What is the treatment for a urine culture positive for coagulase-negative staphylococcus (CoNS)?

Treatment of Coagulase-Negative Staphylococcus in Urine

In most cases, coagulase-negative staphylococci (CoNS) isolated from urine should NOT be treated, as they typically represent contamination or asymptomatic colonization rather than true infection. 1

Determining Clinical Significance

The critical first step is distinguishing true infection from contamination:

• CoNS are "not considered clinically relevant urine isolates" in the majority of cases, particularly in asymptomatic patients 1
• A single positive urine culture with CoNS, especially when in-office testing was negative, strongly suggests contamination or colonization rather than infection 1
• True UTI requires both positive culture AND clinical symptoms (dysuria, frequency, urgency, suprapubic pain, fever, or flank pain) 1

When Treatment IS Indicated

Treatment should only be considered when BOTH of the following are present:

1. Symptomatic Infection

• Lower tract symptoms: dysuria, frequency, urgency, suprapubic pain 1
• Upper tract symptoms: fever, flank pain, costovertebral angle tenderness 2
• Systemic symptoms: rigors, altered mental status, malaise 2

2. High-Risk Clinical Context

Treatment is warranted in patients with: 1

• Indwelling urinary catheter
• Recent urological procedure
• Immunocompromised status
• Pregnancy
• Urinary tract abnormalities (especially in young children and males with pyelonephritis) 3

Treatment Regimens When Indicated

For Uncomplicated Cystitis (Symptomatic Lower UTI):

• Nitrofurantoin for 5 days (first-line) 1
• TMP/SMX for 3 days (alternative first-line) 1

For Pyelonephritis (Upper UTI):

• First-generation cephalosporin for 7 days 1

For Catheter-Associated UTI (CAUTI):

When CoNS causes symptomatic CAUTI, management differs significantly:

• Replace the catheter before starting antibiotics if it has been in place ≥2 weeks 2
• First-line empirical treatment: IV third-generation cephalosporin 2
• Alternative options: amoxicillin plus aminoglycoside, OR second-generation cephalosporin plus aminoglycoside 2
• Duration: 7 days for prompt response; 10-14 days for delayed response; 14 days if prostatitis cannot be excluded in males 2
• Remove the catheter whenever possible before starting antibiotics 2

For Complicated UTI with Systemic Symptoms:

• Amoxicillin plus aminoglycoside 1
• Second-generation cephalosporin plus aminoglycoside 1
• IV third-generation cephalosporin 1

Critical Caveats

Asymptomatic bacteriuria should NOT be treated (except in pregnancy), as treatment promotes antibiotic resistance without clinical benefit 1

Obtain antimicrobial susceptibility testing when treatment is pursued, as methicillin resistance is common among CoNS 2, 4

In young children with CoNS pyelonephritis, particularly males, investigate for underlying urinary tract abnormalities, as 37% have structural anomalies 3

Avoid fluoroquinolones unless local resistance is <10%, the patient hasn't used them in 6 months, and has β-lactam anaphylaxis 2

Special Populations

Neutropenic Patients:

CoNS bacteremia in neutropenic patients rarely causes rapid deterioration, and vancomycin is not routinely needed at fever onset 5. A single positive blood culture should be dismissed as contamination if repeat cultures are negative 5.

Catheterized Patients:

CoNS in catheterized patients most commonly represents colonization rather than infection 2, 6. Treatment is only indicated with symptoms compatible with CAUTI 2.