Enterococci (Group D Streptococci)

Snapshot

• A 55-year-old woman is in the medical intensive care unit for treatment of intractable seizures. She was intubated and sedated with phenobarbital. On hospital day 8, her temperature is 102°F (38.9°C), blood pressure is 102/79 mmHg, and pulse is 102/min. Physical examination is notable for facial grimacing during suprapubic palpation. A Foley catheter had been placed since admission. Urine studies are obtained and a urinalysis is positive for leukocyte esterase. She is started on piperacillin-tazobactam and vancomycin. Urine culture returns positive for enterococci species susceptible to ampicillin. Her empiric antibiotic treatment was narrowed to intravenous ampicillin. (Urinary tract infection)

Introduction

• Classification
  • gram-positive cocci
    • α- or γ-hemolytic
    • grows in 40% bile or 6.5% NaCl
    • catalase negative
    • PYR (pyrrolidonyl arylamidase) positive
  • organisms
    • Enterococcus faecium
    • E. faecalis
• Epidemiology
  • incidence
    • a common cause of nosocomial infections in the United States
    • E. faecalis is the most common enterococci to cause endocarditis
• Reservoir
  • normal colonic flora
• Associated conditions
  • urinary tract infections (UTI)
  • biliary tract infections
  • subacute bacterial endocarditis
• bacteremia

Presentation

• Symptoms
  • UTI
    • urinary frequency or urgency
  • biliary tract infections
    • right upper quadrant pain
  • endocarditis
    • chills
    • anorexia
    • weight loss
    • patients may have tooth pain or related symptoms
• Physical exam
  • UTI
    • dysuria
    • suprapubic pain
  • biliary tract infections
    • Murphy sign
      • arrest of inspiration secondary to pain upon right upper quadrant palpation
  • endocarditis 
    • fevers
• new heart murmur

Studies

• Microbiologic
  • variable hemolysis (α- or γ-hemolytic)
  • PYR positive
• growth in 40% bile or 6.5% NaCl

Differential

• Other causes of UTI
  • differentiating factor
    • E. coli
      • gram-negative rod
    • Staphylococcus saprophyticus
      • catalase-positive, gram-positive cocci
• Other causes of endocarditis
  • differentiating factor
    • Streptococcus viridans 
• α-hemolytic cocci that is optochin resistant and not bile soluble

Treatment

• Treatment approach
  • antibiotic of choice is dependent on susceptibility testing
• Medical
  • amoxicillin, fosfomycin, or nitrofurantoin
    • indication
      • enterococci UTI
  • ampicillin, vancomycin, or daptomycin
    • indication
      • enterococci sepsis
    • comments
      • ampicillin-resistant bacteria that are vancomycin-susceptible are treated with vancomycin or daptomycin
  • ampicillin and gentamicin
    • indication
      • endocarditis caused by enterococci
    • comments
      • other regimens
        • ceftriaxone with ampicillin
        • vancomycin with gentamicin for patients with beta-lactam allergies
  • linezolid
    • indication
      • vancomycin-resistant enterococci (VRE)
        • vancomycin resistance is gained through uptake of a resistance plasmid 

Complications

• UTI
• Biliary tract infections
• Subacute endocarditis
• Sepsis