From the Guidelines
For methicillin-sensitive Staphylococcus aureus (MSSA) bacteremia, the recommended oral treatment is typically dicloxacillin 500 mg four times daily or cephalexin 500 mg four times daily, as supported by the most recent and highest quality study 1. When considering oral therapy for MSSA bacteremia, it is essential to note that this approach is generally reserved for uncomplicated cases where the patient has demonstrated clinical improvement, clearance of bacteremia with negative blood cultures, and the ability to tolerate oral medications 2. The choice of oral antibiotic should be based on the susceptibility of the isolate, with dicloxacillin and cephalexin being preferred options due to their excellent coverage against MSSA, good oral bioavailability, and tissue penetration 3. Key considerations for oral therapy in MSSA bacteremia include:
- The patient should have shown clinical improvement and have negative blood cultures before transitioning to oral therapy.
- The treatment duration should be 2-4 weeks for uncomplicated bacteremia and 4-6 weeks for complicated cases.
- Regular follow-up is crucial to ensure resolution of the infection.
- Oral therapy may not be suitable for all cases, particularly those with endocarditis, persistent bacteremia, or immunocompromised hosts. It is also important to consider the potential for resistance and the need for ongoing monitoring and adjustment of therapy as needed, based on the latest guidelines and evidence 1, 2.
From the FDA Drug Label
The penicillinase-resistant penicillins are indicated in the treatment of infections caused by penicillinase-producing staphylococci which have demonstrated susceptibility to the drugs. The FDA drug label does not answer the question.
From the Research
MSSA Bacteremia Treatment Options
- The treatment of Methicillin-Susceptible Staphylococcus aureus (MSSA) bacteremia typically involves the use of anti-staphylococcal beta-lactams, with cefazolin and antistaphylococcal penicillins (ASPs) being commonly used options 4, 5, 6.
- Cefazolin has been shown to have similar clinical efficacy to ASPs, but with better tolerability and lower rates of discontinuation due to adverse drug reactions 4, 6.
- A meta-analysis of cefazolin versus ASPs for MSSA bacteraemias found a significant decrease in mortality associated with cefazolin therapy, as well as better tolerability 6.
- Other treatment options, such as dalbavancin, have been used in clinical practice for the treatment of MSSA bacteremia, particularly in patients who are ineligible for outpatient parenteral antimicrobial therapy (OPAT) 7.
Oral Treatment Options
- There is limited evidence to support the use of oral antibiotics as a first-line treatment for MSSA bacteremia 8.
- Cefazolin is typically administered intravenously, but oral antibiotics such as cephalexin or dicloxacillin may be used as an alternative in certain cases, although this is not well-studied 4.
- The use of oral antibiotics for MSSA bacteremia should be approached with caution and ideally guided by susceptibility testing and clinical expertise.
Key Findings
- Cefazolin is a viable treatment option for MSSA bacteremia, with similar clinical efficacy to ASPs and better tolerability 4, 5, 6.
- Dalbavancin may be considered as an alternative treatment option for patients who are ineligible for OPAT 7.
- Further research is needed to fully establish the role of oral antibiotics in the treatment of MSSA bacteremia 8.