What are common cocci bacteria associated with urinary tract infections (UTIs)?

Common Cocci Bacteria Associated with UTI

Enterococcus species and Staphylococcus saprophyticus are the most common cocci bacteria associated with urinary tract infections, with S. saprophyticus being the second most common cause of UTIs in young women after E. coli. 1

Major Cocci Bacteria in UTIs

Gram-Positive Cocci

• Staphylococcus saprophyticus: Second most common cause of UTIs in young women, accounting for approximately 11% of UTIs in this population 2
• Enterococcus species (including E. faecalis): Common in complicated UTIs and catheter-associated infections 1, 3
• Coagulase-negative staphylococci: Frequently found in both men and women with asymptomatic bacteriuria 1
• Staphylococcus epidermidis: More common in males with UTIs than in females 4
• Group B streptococci: Can be found in asymptomatic bacteriuria, particularly in women 1

Epidemiology and Clinical Significance

Staphylococcus saprophyticus

• Most frequently affects young, sexually active women 2, 5
• Shows seasonal variation with higher incidence during late summer and early fall 2
• Can cause both lower and upper urinary tract infections 2
• 41% of S. saprophyticus infections may localize to the upper urinary tract, compared to only 16% of E. coli infections 2
• Risk factors include sexual activity and use of spermicide-coated condoms 6

Enterococcus species

• More commonly associated with complicated UTIs 1
• Frequently found in catheter-associated UTIs 1
• Often seen in patients with structural abnormalities of the urinary tract 1
• May be present in healthcare-associated infections 1

Clinical Considerations

Diagnosis

• Urine culture remains the gold standard for identifying the specific bacterial pathogen 1
• For cocci bacteria, a colony count of ≥50,000 CFUs/mL is generally considered significant in symptomatic patients 1
• S. saprophyticus infections may present with lower colony counts than the traditional 100,000 CFUs/mL threshold 5

Treatment

• S. saprophyticus is generally susceptible to most antibiotics used for UTIs, except nalidixic acid 5
• Enterococcus species may require specific antibiotic coverage, as they are intrinsically resistant to many cephalosporins 3
• Ciprofloxacin is effective against both Enterococcus faecalis and Staphylococcus saprophyticus 3
• For uncomplicated UTIs, nitrofurantoin, trimethoprim-sulfamethoxazole, or fosfomycin are recommended first-line options 7

Special Populations

Catheterized Patients

• Enterococcus species are among the most common organisms in catheter-associated UTIs 1
• Patients with indwelling catheters acquire bacteriuria at a rate of 3-8% per day 1
• Coagulase-negative staphylococci are common in catheterized patients 1

Elderly Patients

• 25-50% of elderly women and 15-40% of elderly men in long-term care facilities have bacteriuria, often with mixed flora including gram-positive cocci 1
• The clinical assessment of bacteriuria in elderly patients can be challenging, as symptoms may be atypical 1

Men

• Coagulase-negative staphylococci are common in men with UTIs, in addition to gram-negative bacilli and Enterococcus species 1
• S. aureus may be found in male UTIs more frequently than in females 4

Antimicrobial Resistance Considerations

• Local antimicrobial resistance patterns should guide empiric therapy choices 1
• S. saprophyticus generally remains susceptible to most UTI antibiotics 5
• Enterococcus species may exhibit resistance to multiple antibiotics, particularly in healthcare settings 1