What is the initial treatment for a patient with a positive viridans streptococcus blood culture?

From the Guidelines

The initial treatment for a patient with a positive viridans streptococcus blood culture is aqueous crystalline penicillin G sodium at a dose of 24 million U/24 h IV, either continuously or in 4-6 equally divided doses, for 4 weeks, as recommended by the American Heart Association 1. This treatment is based on the most recent and highest quality study available, which provides guidelines for the diagnosis, antimicrobial therapy, and management of complications of infective endocarditis in adults. The use of penicillin G is recommended due to its effectiveness against viridans streptococci, with a bacteriologic cure rate of 98% when used for 4 weeks 1. For patients who are unable to tolerate penicillin, vancomycin hydrochloride at a dose of 30 mg/kg per 24 h IV in 2 equally divided doses for 4 weeks is a recommended alternative 1. It is also important to consider the use of gentamicin sulfate in combination with penicillin or ceftriaxone for the first 2 weeks of treatment, especially for patients with complicated infections or those who are at high risk for adverse events 1. Some key points to consider when treating a patient with a positive viridans streptococcus blood culture include:

• The duration of treatment, which typically ranges from 2 weeks for uncomplicated bacteremia to 4-6 weeks for endocarditis or other complicated infections
• The importance of repeating blood cultures to ensure clearance of the bacteremia
• The need to investigate the source of infection, as viridans streptococci commonly originate from the oral cavity, gastrointestinal tract, or genitourinary system
• The consideration of an echocardiogram to rule out endocarditis, particularly in patients with predisposing cardiac conditions, persistent fever, or new murmurs. Overall, the treatment of viridans streptococcus bacteremia requires careful consideration of the patient's individual needs and the potential complications of the infection.

From the FDA Drug Label

Vancomycin Hydrochloride for Injection, USP has been reported to be effective alone or in combination with an aminoglycoside for endocarditis caused by S. viridans or S. bovis.

The initial treatment for a patient with a positive viridans streptococcus blood culture may include vancomycin alone or in combination with an aminoglycoside for endocarditis caused by S. viridans 2.

From the Research

Initial Treatment for Viridans Streptococcus Blood Culture

The initial treatment for a patient with a positive viridans streptococcus blood culture depends on various factors, including the susceptibility of the organism to antibiotics and the presence of any underlying conditions.

• Ceftriaxone (CTX) and penicillin G (PCN G) are considered reasonable treatment options for viridans group streptococci (VGS) bloodstream infections 3.
• For patients with infective endocarditis caused by viridans streptococci highly susceptible to penicillin, antimicrobial treatment with penicillin or a combination of penicillin and streptomycin may be effective 4, 5.
• In cases where the viridans streptococci are penicillin non-susceptible, ceftriaxone monotherapy may be a successful treatment option 6.
• The choice of antibiotic therapy should be guided by the results of susceptibility testing and the clinical presentation of the patient.

Considerations for Treatment

• The treatment duration for viridans streptococci endocarditis is typically four weeks, but shorter treatment durations may be effective in select patients 4.
• The use of high-dose antibiotics, such as penicillin, may be necessary to ensure effective treatment 4.
• The combination of penicillin and streptomycin may be more effective than penicillin alone in treating endocarditis caused by penicillin-tolerant or penicillin-resistant viridans streptococci 7.

Antibiotic Options

• Penicillin G (PCN G) is a commonly used antibiotic for treating viridans streptococci infections 3, 5.
• Ceftriaxone (CTX) is a cephalosporin antibiotic that may be effective in treating viridans streptococci infections, including those caused by penicillin non-susceptible strains 3, 6.
• Streptomycin may be used in combination with penicillin to treat endocarditis caused by viridans streptococci 4, 5, 7.