What is the empiric antibiotic therapy for septic (Staphylococcal) arthritis and surrounding osteomyelitis and abscess?

From the Guidelines

For empiric antibiotic therapy of septic arthritis with surrounding osteomyelitis and abscess, I recommend starting with vancomycin 15-20 mg/kg IV every 8-12 hours plus ceftriaxone 2g IV daily, as this combination provides broad coverage against common pathogens, including Staphylococcus aureus (including MRSA), Streptococcus species, and Gram-negative organisms 1.

Key Considerations

• The choice of vancomycin is based on its effectiveness against MRSA, which is a common cause of septic arthritis and osteomyelitis, as recommended by the Infectious Diseases Society of America 1.
• Ceftriaxone is added to provide coverage against Gram-negative organisms, including Salmonella, which is particularly important in certain patient populations, such as those with sickle cell disease.
• For severe infections or immunocompromised patients, consider adding an antipseudomonal agent like cefepime 2g IV every 8 hours instead of ceftriaxone.
• Treatment duration should be at least 4-6 weeks for osteomyelitis, with the first 2 weeks typically administered intravenously, as suggested by the guidelines for the treatment of MRSA infections 1.

Additional Recommendations

• Surgical drainage of any abscess is essential alongside antibiotic therapy, as emphasized in the guidelines for the treatment of MRSA infections 1.
• Once culture and sensitivity results return, narrow therapy appropriately to minimize the risk of antibiotic resistance and side effects.
• Monitor renal function, drug levels for vancomycin, and clinical response to adjust the treatment plan as needed.
• Consider the use of other antibiotics, such as clindamycin or linezolid, as alternative or adjunctive therapy, based on the specific clinical scenario and local epidemiology 1.

From the FDA Drug Label

The efficacy endpoints in both trials were the clinical success rates in the intent-to-treat (ITT) population and in the clinically evaluable (CE) population. Table 16: Clinical Success Rates by Infecting Pathogen in the cSSSI Trials in Adult Patients (Population: Microbiologically Evaluable) Pathogen Success Rate n/N (%) Daptomycin for Injection Comparator* Methicillin-susceptible Staphylococcus aureus (MSSA) † 170/198 (86%) 180/207 (87%) Methicillin-resistant Staphylococcus aureus (MRSA) † 21/28 (75%) 25/36 (69%) Streptococcus pyogenes 79/84 (94%) 80/88 (91%) Streptococcus agalactiae 23/27 (85%) 22/29 (76%) Streptococcus dysgalactiae subsp. equisimilis 8/8 (100%) 9/11 (82%) Enterococcus faecalis (vancomycin-susceptible only) 27/37 (73%) 40/53 (76%) *Comparator: vancomycin (1 g IV q12h) or an anti-staphylococcal semi-synthetic penicillin (i.e., nafcillin, oxacillin, cloxacillin, or flucloxacillin; 4 to 12 g/day IV in divided doses).

The empiric antibiotic therapy for SC septic arthritis and surrounding osteomyelitis and abscess may include:

• Vancomycin (1 g IV q12h)
• Anti-staphylococcal semi-synthetic penicillin (i.e., nafcillin, oxacillin, cloxacillin, or flucloxacillin; 4 to 12 g/day IV in divided doses) as these were used as comparators in the trials and showed clinical success rates against various pathogens, including Methicillin-susceptible Staphylococcus aureus (MSSA) and Methicillin-resistant Staphylococcus aureus (MRSA) 2.

From the Research

Empiric Antibiotic Therapy for SC Septic Arthritis and Surrounding Osteomyelitis and Abscess

• The most common pathogen isolated in septic arthritis is Staphylococcus aureus, including Methicillin-Sensitive Staphylococcus aureus (MSSA) and Methicillin-Resistant Staphylococcus aureus (MRSA) 3, 4.
• Empiric antibiotic therapy should be initiated if there is clinical concern for septic arthritis, and oral antibiotics can be given in most cases because they are not inferior to intravenous therapy 3.
• The choice of empiric antibiotic therapy should cover MRSA, especially in patients at risk, such as those with recent joint surgery, hip or knee prosthesis, skin infection, or immunosuppressive medication use 3, 5.
• Vancomycin is a commonly recommended empiric antibiotic therapy for MRSA 5, 6, 7.
• The total duration of therapy ranges from two to six weeks, but certain infections may require longer courses 3.
• It is essential to identify the causative organism and adjust antibiotic therapy accordingly, as well as to consider source control, such as removal of infected intravascular or implanted devices, drainage of abscesses, and surgical debridement 7.

Causative Organisms and Risk Factors

• The most common bacteria isolated in septic arthritis are MSSA, MRSA, Coagulase-Negative Staphylococci (CoNS), and Group B Streptococcus (GBS) 4.
• Risk factors for septic arthritis include age older than 80 years, diabetes mellitus, rheumatoid arthritis, recent joint surgery, hip or knee prosthesis, skin infection, and immunosuppressive medication use 3.
• MRSA is more commonly associated with shoulder septic arthritis, while MSSA is the leading causative organism in other joints 4.

Treatment Outcomes and Mortality

• Delayed or inadequate treatment of septic arthritis can result in joint destruction, osteomyelitis, and sepsis 4.
• MRSA septic arthritis is associated with higher mortality than MSSA arthritis 5.
• Empiric antibiotic therapy is crucial in reducing mortality and improving outcomes in septic arthritis 3, 5, 7.