What is the recommended IV antibiotic regimen for a large abscess on the skin over the knee caused by Staphylococcus (Staph)?

From the Guidelines

For a large abscess on the skin over the knee caused by Staphylococcus, the recommended IV antibiotic regimen typically includes vancomycin 15-20 mg/kg IV every 8-12 hours (not to exceed 2g per dose) or daptomycin 4-6 mg/kg IV once daily, as these regimens have been shown to be effective in treating complicated skin and soft tissue infections (cSSTI) caused by methicillin-resistant Staphylococcus aureus (MRSA) 1.

Key Considerations

• The choice of antibiotic should be guided by the severity of the infection, the presence of comorbidities, and the susceptibility of the organism to the antibiotic.
• Surgical drainage of the abscess is a crucial component of treatment and should be performed alongside antibiotic therapy.
• Blood cultures should be obtained before starting antibiotics to guide therapy.
• Once clinical improvement is observed and culture results with susceptibilities are available, transition to oral antibiotics may be appropriate to complete the treatment course.

Antibiotic Options

• Vancomycin is the preferred first-line agent for MRSA infections, with a recommended dose of 15-20 mg/kg IV every 8-12 hours (not to exceed 2g per dose) 1.
• Daptomycin is an alternative option for MRSA infections, with a recommended dose of 4-6 mg/kg IV once daily 1.
• For methicillin-sensitive Staphylococcus aureus (MSSA) infections, nafcillin or oxacillin 2g IV every 4 hours can be used 1.

Treatment Duration

• Treatment duration is generally 7-14 days, depending on clinical response 1.
• The treatment course should be individualized based on the patient's clinical response and the results of culture and susceptibility testing.

Additional Considerations

• It is essential to note that the use of antibiotics should be guided by the principles of antimicrobial stewardship, and the choice of antibiotic should be based on the most recent and highest-quality evidence available 1.
• The patient's clinical response and the results of culture and susceptibility testing should guide the treatment course, and adjustments to the antibiotic regimen should be made as necessary.

From the FDA Drug Label

Adult patients with clinically documented complicated skin and skin structure infections (cSSSI) ... were enrolled in two randomized, multinational, multicenter, investigator-blinded trials comparing daptomycin for injection (4 mg/kg IV q24h) with either vancomycin (1 g IV q12h) or an anti-staphylococcal semi-synthetic penicillin (i.e., nafcillin, oxacillin, cloxacillin, or flucloxacillin; 4 to 12 g IV per day).

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%)

The recommended IV antibiotic regimen for a large abscess on the skin over the knee caused by Staphylococcus is daptomycin for injection (4 mg/kg IV q24h) or vancomycin (1 g IV q12h) or an anti-staphylococcal semi-synthetic penicillin (i.e., nafcillin, oxacillin, cloxacillin, or flucloxacillin; 4 to 12 g IV per day) 2.

• Clinical success rates for Methicillin-susceptible Staphylococcus aureus (MSSA) were 86% for daptomycin and 87% for the comparator.
• Clinical success rates for Methicillin-resistant Staphylococcus aureus (MRSA) were 75% for daptomycin and 69% for the comparator.

From the Research

Recommended IV Antibiotic Regimen

For a large abscess on the skin over the knee caused by Staphylococcus, the recommended IV antibiotic regimen depends on the susceptibility of the strain.

• If the strain is methicillin-susceptible Staphylococcus aureus (MSSA), penicillinase-resistant penicillins (flucloxacillin, dicloxacillin) are the antibiotics of choice 3.
• For less serious MSSA infections, first-generation cephalosporins (cefazolin, cephalothin, and cephalexin), clindamycin, lincomycin, and erythromycin can be used, although cephalosporins are contraindicated in patients with immediate penicillin hypersensitivity 3.
• If the strain is methicillin-resistant Staphylococcus aureus (MRSA), vancomycin is the first-line treatment 4, 5.
• Alternative treatments for MRSA infections include linezolid, daptomycin, tigecycline, and quinupristin/dalfopristin 5.
• Daptomycin has been shown to be effective in treating MRSA osteoarticular infections, including those that have not responded to vancomycin 6.
• Ceftaroline has also demonstrated potent in vitro activity against staphylococci with reduced susceptibility to linezolid, daptomycin, or vancomycin 7.

Considerations for Treatment

When selecting an IV antibiotic regimen, it is essential to consider the severity of the infection, the susceptibility of the strain, and the patient's medical history, including any allergies or previous antibiotic use 3, 4, 5, 6.

• The treatment regimen should be tailored to the individual patient's needs, and the patient should be closely monitored for signs of improvement or adverse reactions 4, 6.
• In cases where the patient has a history of vancomycin allergy or has not responded to vancomycin, alternative treatments such as daptomycin or linezolid may be considered 4, 5, 6.