How to manage a patient with gram-positive cocci isolated from one anaerobic bottle of a blood culture?

From the Guidelines

Gram-positive cocci growth in one anaerobic bottle of a blood culture is likely a contaminant and does not warrant immediate antibiotic treatment, especially if further blood cultures are negative, as suggested by the national guidelines for the judicious use of glycopeptides in Belgium 1. When managing a patient with gram-positive cocci isolated from one anaerobic bottle of a blood culture, it is essential to consider the possibility of contamination, particularly if the isolate is a common skin commensal like coagulase-negative staphylococci.

• Key considerations include:
  • Clinical stability of the patient
  • Presence of risk factors for endocarditis, immunosuppression, or prosthetic devices
  • Results of additional blood cultures
• If the patient is clinically stable, collecting two additional sets of blood cultures before starting antibiotics is recommended to confirm or rule out true bacteremia.
• For unstable patients or those with specific risk factors, empiric therapy with vancomycin may be initiated, but this should be guided by the most recent and highest quality evidence available, which in this case, suggests caution against immediate treatment based on a single positive culture 1.
• A thorough clinical examination and additional tests, such as complete blood count and basic metabolic panel, are crucial in determining the source and severity of the potential infection.
• The decision to continue or discontinue antibiotics should be based on the final identification and susceptibility results of the isolate, as well as the patient's clinical response.
• In cases where the isolate is confirmed to be a contaminant, such as coagulase-negative staphylococci, and repeat cultures are negative, antibiotics may be safely discontinued in clinically well patients, minimizing unnecessary antibiotic exposure and its associated risks.

From the FDA Drug Label

The FDA drug label does not answer the question.

From the Research

Management of Gram-Positive Cocci in Blood Cultures

• The management of a patient with gram-positive cocci isolated from one anaerobic bottle of a blood culture involves differentiating contamination from infection 2.
• Organism identification can provide supportive information for this differentiation, and rapid polymerase chain reaction-based organism identification can help in this process 2.
• However, the presence of gram-positive cocci in one anaerobic bottle of a blood culture does not necessarily indicate infection, as coagulase-negative staphylococci, which are commonly isolated, can be contaminants 2, 3.

Identification and Classification of Gram-Positive Anaerobic Cocci

• Gram-positive anaerobic cocci (GPAC) are a heterogeneous group of organisms that are part of the normal flora of mucocutaneous surfaces and can be isolated from various infections 3, 4.
• The classification of GPAC has undergone changes over the years, with the development of molecular identification methods leading to the recognition of new species and the renaming of existing ones 3, 4.
• Biochemical characterization and 16S rRNA gene sequencing can be used for the identification of GPAC species 5.

Clinical Significance and Treatment

• GPAC can cause serious infections, including deep organ abscesses, obstetric and gynecological sepsis, and intraoral infections 3, 4.
• The treatment of GPAC infections depends on the species and its antibiotic susceptibility profile, with penicillins being the antibiotics of choice for many species 4.
• In the case of hemodialysis patients, the management of gram-positive coccal bacteremia is complicated by limited vascular access options and the increasing prevalence of drug-resistant bacteria 6.