What is the recommended antibiotic combination for a patient with a peritonsillar abscess, history of methicillin-resistant Staphylococcus aureus (MRSA) skin infections, and impaired renal function?

From the Guidelines

For a patient with a peritonsillar abscess, history of MRSA skin infections, and impaired renal function, the recommended antibiotic combination is vancomycin and ampicillin-sulbactam, with careful monitoring of vancomycin levels and dose adjustment based on renal function. This recommendation is based on the need to cover both MRSA and the typical polymicrobial aerobic and anaerobic organisms found in peritonsillar abscesses. Vancomycin is effective against MRSA, but its use requires careful monitoring due to the risk of nephrotoxicity, especially in patients with impaired renal function, as noted in the guidelines for managing adults with hospital-acquired pneumonia 1.

The patient's history of MRSA skin infections necessitates coverage for this pathogen, and vancomycin, despite its potential drawbacks, remains a standard treatment option. However, the patient's impaired renal function, with an eGFR of 34 mL/min/1.73 m^2, necessitates careful dose adjustment to avoid nephrotoxicity. Ampicillin-sulbactam provides broad coverage against aerobic and anaerobic organisms commonly found in peritonsillar abscesses, complementing vancomycin's anti-MRSA activity.

Key considerations in managing this patient include:

• Monitoring vancomycin trough levels to ensure therapeutic levels are achieved while minimizing the risk of nephrotoxicity 1.
• Adjusting the dose of vancomycin based on renal function, as the patient's impaired renal function may affect drug clearance.
• Ensuring adequate coverage against polymicrobial infections with ampicillin-sulbactam.
• Considering the potential need for surgical drainage of the abscess alongside antibiotic therapy.
• Planning for a treatment duration of 10-14 days, with the possibility of transitioning to oral antibiotics once clinical improvement is observed.

Given the patient's complex clinical presentation, including impaired renal function and a history of MRSA infections, vancomycin and ampicillin-sulbactam offer a balanced approach to managing the peritonsillar abscess while addressing the specific challenges posed by the patient's medical history and current renal status, as informed by the principles outlined in the management of hospital-acquired pneumonia 1.

From the FDA Drug Label

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 2 The cure rates by pathogen for microbiologically evaluable patients are presented in Table 18. Pathogen Cured ZYVOX n/N (%) Oxacillin/Dicloxacillin n/N (%) Methicillin-resistant S aureus 2/3 (67) 0/0 (-) The overall Adjudication Committee success rates in the ITT population were 44.2% (53/120) in patients treated with daptomycin for injection and 41.7% (48/115) in patients treated with comparator (difference = 2.4% [95% CI −10.2,15.1]) 3

The recommended antibiotic combination for a patient with a peritonsillar abscess, history of methicillin-resistant Staphylococcus aureus (MRSA) skin infections, and impaired renal function is Vancomycin and ampicillin-sulbactam.

• Vancomycin is effective against MRSA, with a cure rate of 73% in microbiologically evaluable patients with MRSA skin and skin structure infection 2.
• Ampicillin-sulbactam provides broad-spectrum coverage, including anaerobes that may be involved in peritonsillar abscesses. This combination is a reasonable choice, given the patient's history of MRSA skin infections and the need for broad-spectrum coverage in a peritonsillar abscess. However, it is essential to note that the FDA drug label does not directly address the treatment of peritonsillar abscesses. Key considerations:
• Monitor renal function closely, as vancomycin and ampicillin-sulbactam may affect kidney function.
• Adjust doses according to renal function, if necessary.
• Consider consulting an infectious disease specialist for further guidance.

From the Research

Patient Profile

• 28-year-old woman with type 2 diabetes mellitus
• History of methicillin-resistant Staphylococcus aureus (MRSA) skin infections
• Presents with throat pain, fever, and difficulty swallowing
• Diagnosed with a 3x4-cm right peritonsillar abscess

Laboratory Results

• Leukocyte count: 18,000 H [4000-11,000/pL]
• Segmented neutrophils: 92 H [50%-70%]
• Plasma glucose: 360 H [70-99 mg/dL]
• Blood urea nitrogen: 34 H [8-20 mg/dL]
• Serum creatinine: 2.00 H [0.50-1.10 mg/dL]
• eGFR: 34 [mL/min/1.73 m2]

Recommended Antibiotic Combination

Based on the patient's history of MRSA skin infections and the presence of a peritonsillar abscess, the recommended antibiotic combination should cover MRSA and other gram-positive cocci. The following options are considered:

• Vancomycin is a suitable option for treating MRSA infections, as stated in 4 and 5
• Ampicillin-sulbactam is a broad-spectrum antibiotic that can cover a range of gram-positive and gram-negative bacteria
• Considering the patient's impaired renal function, the dosage of vancomycin may need to be adjusted, as mentioned in 6

Suggested Treatment

The most appropriate antibiotic combination for this patient would be:

• Vancomycin and ampicillin-sulbactam, as this combination provides coverage for MRSA and other gram-positive and gram-negative bacteria, as discussed in 5 and 7

Key points to consider:

• The patient's history of MRSA skin infections and the presence of a peritonsillar abscess require antibiotic coverage for MRSA
• Vancomycin is a suitable option for treating MRSA infections, but its dosage may need to be adjusted due to the patient's impaired renal function
• Ampicillin-sulbactam provides broad-spectrum coverage for other gram-positive and gram-negative bacteria