What are common Gram-positive cocci found in urine cultures?

From the Guidelines

Common gram-positive cocci found in urine cultures include Staphylococcus saprophyticus, Enterococcus species (particularly E. faecalis and E. faecium), Staphylococcus aureus, and Streptococcus agalactiae (Group B Streptococcus). These organisms can cause a range of urinary tract infections (UTIs), from uncomplicated to complicated infections.

Key Organisms and Their Significance

• Staphylococcus saprophyticus is particularly significant as the second most common cause of uncomplicated urinary tract infections in young, sexually active women 1.
• Enterococci are often associated with complicated UTIs, especially in hospitalized patients or those with structural abnormalities of the urinary tract 1.
• S. aureus in urine may indicate either a primary UTI or bacteremia with secondary seeding of the urinary tract.
• Group B Streptococcus is especially concerning in pregnant women as it can cause neonatal infections.

Treatment Considerations

When treating these infections, antibiotic selection should be guided by susceptibility testing, with options including:

• Nitrofurantoin, trimethoprim-sulfamethoxazole, or fluoroquinolones for uncomplicated infections.
• More severe or complicated infections may require ampicillin, vancomycin, or linezolid depending on resistance patterns 1. It's essential to consider local resistance patterns and specific host factors, such as allergies, when selecting antimicrobial therapy 1.

Recent Guidelines and Recommendations

The European Association of Urology guidelines on urological infections recommend considering the microbial spectrum and antimicrobial resistance when selecting empirical antimicrobial therapy for complicated UTIs 1. Given the most recent evidence from 2024, the European Association of Urology guidelines provide the most up-to-date recommendations for managing urological infections, including those caused by gram-positive cocci 1.

From the Research

Common Gram-Positive Cocci in Urine Cultures

• Enterococcus faecalis is a common cause of urinary tract infections, accounting for 85% of enterococci isolated from urine 2
• Staphylococcus aureus is also a common gram-positive coccus found in urine cultures, with 18 (29%) of 62 staphylococcal isolates identified as S. aureus 2
• Other gram-positive cocci found in urine cultures include:
  • Enterococcus faecium 2, 3
  • Coagulase-negative staphylococci, such as Staphylococcus haemolyticus 2
  • Beta-hemolytic streptococci, including group B, group G, and group F 2

Species Distribution

• Enterococcus species are commonly isolated from urine cultures, with E. faecalis being the most prevalent 2, 3, 4
• Staphylococcus species, including S. aureus and coagulase-negative staphylococci, are also frequently isolated from urine cultures 2, 5
• Streptococcus species, including beta-hemolytic streptococci, are less commonly isolated from urine cultures 2

Clinical Significance

• Gram-positive cocci can cause significant urinary tract infections, particularly in patients with underlying medical conditions or those who have undergone catheterization 5, 4
• The increasing prevalence of enterococcal urinary tract infections may be due to the rising use of broad-spectrum antibiotics and catheterization 4
• Biofilm formation and multi-drug resistance are significant concerns in gram-positive cocci isolated from urine cultures, particularly in catheter-associated urinary tract infections 5