What is the appropriate treatment for a wound infection on the right 2nd toe, with heavy growth of Methicillin (Oxacillin) Resistant Staphylococcus aureus (MRSA) and Beta Hemolytic Streptococcus Group C, and negative anaerobic culture?

From the Guidelines

The patient with a wound culture showing heavy growth of Methicillin-resistant Staphylococcus aureus (MRSA) and Group C beta-hemolytic Streptococcus should be treated with vancomycin, linezolid, daptomycin, or trimethoprim-sulfamethoxazole, with vancomycin being a good first-line choice for severe infections, as recommended by the Infectious Diseases Society of America guidelines 1. The choice of antibiotic should be based on the severity of the infection, with vancomycin typically dosed at 15-20 mg/kg IV every 8-12 hours with appropriate monitoring of trough levels for severe infections. For less severe infections, oral options include trimethoprim-sulfamethoxazole (1-2 double-strength tablets twice daily) or linezolid (600 mg twice daily) for 7-14 days depending on clinical response 1. Some key points to consider in the treatment of this polymicrobial infection include:

• The importance of covering both MRSA and Group C beta-hemolytic Streptococcus with the chosen antibiotic regimen
• The need for proper wound care, including regular cleaning, debridement of necrotic tissue if present, and appropriate dressing changes
• The importance of monitoring the patient for clinical improvement, including decreased pain, erythema, swelling, and drainage from the wound
• The potential for resistance to multiple antibiotics, including oxacillin, ciprofloxacin, clindamycin, erythromycin, levofloxacin, and tetracycline, and the need to choose an antibiotic that is effective against both organisms 1. In addition to antibiotic therapy, it is essential to practice contact precautions to prevent the spread of MRSA to other patients or healthcare workers 1.

From the FDA Drug Label

Daptomycin for injection is indicated for the treatment of adult and pediatric patients (1 to 17 years of age) with complicated skin and skin structure infections (cSSSI) caused by susceptible isolates of the following Gram-positive bacteria: Staphylococcus aureus (including methicillin-resistant isolates) The cure rates in microbiologically evaluable patients with MRSA skin and skin structure infection were 26/33 (79%) for linezolid-treated patients and 24/33 (73%) for vancomycin-treated patients

The patient has a complicated skin and skin structure infection (cSSSI) caused by Methicillin-resistant Staphylococcus aureus (MRSA).

• Daptomycin and Linezolid are potential treatment options for this patient.
• The cure rate for MRSA skin and skin structure infections with Linezolid is 79% and with Vancomycin is 73%.
• Daptomycin is indicated for the treatment of cSSSI caused by MRSA, but the cure rate is not specified in the provided text. Based on the provided information, Linezolid and Daptomycin can be considered as treatment options for this patient, but the choice of treatment should be based on the specific clinical situation and susceptibility patterns 2, 3.

From the Research

Wound Culture Results

• The wound anaerobic culture showed no growth and no anaerobes were isolated.
• The wound aerobic culture showed no growth, but the organism #1 was identified as heavy growth of methicillin (oxacillin) resistant Staph aureus (MRSA).
• The organism #2 was identified as heavy growth of beta hemolytic strep group C, large colony, which was methicillin (oxacillin) resistant.

Treatment Options for MRSA

• According to the study 4, combination antibiotic treatment for MRSA infections is an attractive alternative to vancomycin, but the theoretical promise of combination therapy has not been borne out in most in vitro and animal studies.
• The study 5 suggests that vancomycin remains an acceptable treatment option for MRSA, and daptomycin is currently the only antibiotic to have shown noninferiority to vancomycin in the treatment of MRSA bacteremia.
• The study 6 recommends empirical antibiotic treatment with vancomycin or daptomycin for MRSA bacteremia, and once susceptibilities are known, MSSA should be treated with cefazolin or an antistaphylococcal penicillin.
• The study 7 suggests that linezolid could be a potential first-line drug against MRSA bacteremia, with comparable effectiveness and safety to vancomycin, teicoplanin, or daptomycin.

Contact Precautions for MRSA

• The study 8 found little evidence that contact precautions reduced MRSA transmission in intensive care units, with an estimated change in transmission attributed to contact precautions of -16% (95% credible interval, -38% to 15%).
• However, contact precautions are still recommended for patients with MRSA, as stated in the wound culture results.

Antibiotic Susceptibility

• The organism #1 (MRSA) was susceptible to ceftaroline, daptomycin, gentamicin, linezolid, rifampin, tigecycline, trimethoprim/sulfamethoxazole, and vancomycin, but resistant to ciprofloxacin, clindamycin, erythromycin, levofloxacin, and oxacillin.
• The organism #2 (beta hemolytic strep group C) was not fully tested for antibiotic susceptibility, but was methicillin (oxacillin) resistant.