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Cocos Gram-positivos

Streptococcus gallolyticus (antigo S. bovis)

Gram-positive cocci in short chains

Identification & Growth

Identification

  • Lancefield group D-positive, bile-esculin-positive, does not grow in 6.5% NaCl (differs from Enterococcus)
  • PYR-negative

Growth Conditions

  • Blood agar, 35–37 °C, CO2; alpha- or non-hemolytic colonies

Clinical Significance

  • Endocarditis and bacteremia associated with colonic neoplasia
  • Hepatobiliary infection

Intrinsic Resistance

  • Low activity of aminoglycosides used alone

Bench Alerts

  • Isolation in blood culture warrants flagging colonoscopy investigation
  • Do not confuse with Enterococcus: the 6.5% NaCl test is the differentiator

Clinical Notes

Clinical presentations

  • Causes infective endocarditis, frequently affecting native valves in elderly patients.
  • Bacteremia due to S. gallolyticus is strongly associated with underlying colorectal neoplasia, even if asymptomatic.
  • Can cause meningitis and abscesses in rare cases, especially in populations with underlying hepatobiliary disease.

Specimens and collection

  • Serial blood cultures are essential for diagnosing bacteremia and endocarditis, per modified Duke criteria.
  • Transesophageal echocardiogram is recommended in every patient with confirmed bacteremia by this organism, given the strong association with endocarditis.
  • Colonoscopy should be indicated in every case of confirmed bacteremia or endocarditis, to investigate colorectal neoplasia.

Epidemiology and at-risk populations

  • Well-established association between bacteremia/endocarditis due to this organism and colorectal adenoma or carcinoma justifies systematic investigation.
  • Elderly patients and those with chronic liver disease have higher incidence of bacteremia due to this organism.

Resistance and therapeutic implications

  • Remains generally highly susceptible to penicillin, which is the mainstay of treatment for uncomplicated endocarditis.
  • Combination with an aminoglycoside may be considered in endocarditis for bactericidal synergy, per endocarditis management guidelines.
  • Ceftriaxone is an effective alternative in patients with mild penicillin allergy or to facilitate outpatient treatment.

Bench and reporting notes

  • Taxonomic reclassification from Streptococcus bovis to the S. gallolyticus complex should be correctly reflected in the microbiology report.
  • Subspecies-level identification (gallolyticus vs. pasteurianus) has clinical relevance due to differing strength of association with colorectal neoplasia.
  • Positive blood culture report for this organism should recommend colonoscopic investigation to the treating clinician.

Sources

Educational decision-support content. It does not replace laboratory validation, current guidelines or review by the responsible professional.

FAQ: Frequently Asked Questions

How to identify Streptococcus gallolyticus (antigo S. bovis) in the lab?

Streptococcus gallolyticus (antigo S. bovis) is identified through lancefield group d-positive, bile-esculin-positive, does not grow in 6.5% nacl (differs from enterococcus), pyr-negative.

What are the intrinsic resistances of Streptococcus gallolyticus (antigo S. bovis)?

This organism is naturally resistant to low activity of aminoglycosides used alone. These drugs should not be reported as susceptible.

Where is Streptococcus gallolyticus (antigo S. bovis) commonly found?

It is typically associated with endocarditis and bacteremia associated with colonic neoplasia, hepatobiliary infection.

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