What antibiotic is recommended for a patient with an allergy to Augmentin (amoxicillin-clavulanate) and Quinolone (fluoroquinolone) who has pneumonia with Methicillin-resistant Staphylococcus aureus (MRSA) and mixed Gram-positive and Gram-negative organisms?

From the Guidelines

For a patient with pneumonia caused by MRSA and gram-negative bacteria who has allergies to Augmentin and quinolones, I recommend intravenous vancomycin plus aztreonam as the initial treatment regimen. This recommendation is based on the guidelines for the management of adults with hospital-acquired and ventilator-associated pneumonia, as outlined in the 2016 clinical practice guidelines by the Infectious Diseases Society of America and the American Thoracic Society 1. Vancomycin effectively targets MRSA, and aztreonam provides coverage against gram-negative organisms without cross-reactivity with beta-lactam allergies.

The dosing of vancomycin should be tailored to the patient's renal function and drug levels, with a goal to achieve trough levels between 15-20 μg/mL for MRSA pneumonia 1. Aztreonam can be administered at a dose of 2 g IV every 8 hours. It's crucial to monitor renal function closely in patients receiving vancomycin and to adjust the dose as necessary to avoid nephrotoxicity.

Key considerations in the management of such patients include:

• The severity of the patient's allergic reactions to guide the choice of antibiotics
• Local resistance patterns to inform the selection of empiric therapy
• The patient's clinical condition, including the severity of pneumonia and any underlying health issues
• The potential need for combination therapy to cover both MRSA and gram-negative pathogens effectively

Alternative options, such as linezolid plus aztreonam, may be considered if vancomycin cannot be used, taking into account the patient's specific situation and the potential for adverse effects or interactions 1. However, vancomycin plus aztreonam remains the preferred choice for initial empiric treatment in patients with MRSA and gram-negative pneumonia who have allergies to Augmentin and quinolones, given its efficacy and the guidelines' recommendations 1.

From the FDA Drug Label

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]). Adjudication Committee success rates are shown in Table 17. Among patients with persisting or relapsing S. aureus infections, 8/19 daptomycin for injection-treated patients and 7/11 comparator-treated patients died The clinical success rates determined at 7 to 14 days after last dose of therapy (IV and oral) (TOC visit) were 88% (45/51) for daptomycin for injection and 77% (17/22) for comparator

Daptomycin is a potential option for a patient with an allergy to Augmentin and quinolone who has pneumonia with MRSA (gram-positive) and gram-negative bacteria.

• The clinical success rates for daptomycin were 88% in the pediatric S. aureus bacteremia study.
• Daptomycin for injection was compared to a comparator, which included vancomycin, semi-synthetic penicillin, first generation cephalosporin or clindamycin.
• The Adjudication Committee success rates for daptomycin were 44.2% in the ITT population. 2

From the Research

Recommended Antibiotics for Pneumonia

Given the patient's allergy to Augmentin and quinolone, and the presence of MRSA (methicillin-resistant Staphylococcus aureus) gram-positive and gram-negative pneumonia, the following antibiotics are recommended:

• Linezolid: According to studies 3, 4, 5, 6, linezolid is a suitable alternative to vancomycin for the treatment of MRSA pneumonia, with some studies suggesting its superiority in terms of clinical success and survival.
• Vancomycin: Although vancomycin is still considered a drug of choice for MRSA pneumonia, its use may be limited due to the risk of nephrotoxicity 4, 5.
• Aztreonam-avibactam: This antibiotic combination has shown potent activity against gram-negative bacteria, including those resistant to other antibiotics 7.

Considerations for Antibiotic Selection

When selecting an antibiotic, the following factors should be considered:

• The patient's allergy history: In this case, the patient is allergic to Augmentin and quinolone, which may limit the use of certain antibiotics.
• The type of pneumonia: MRSA pneumonia requires antibiotics that are effective against gram-positive bacteria, while gram-negative pneumonia requires antibiotics that are effective against gram-negative bacteria.
• The risk of nephrotoxicity: Vancomycin may not be the best choice due to its potential for nephrotoxicity, especially in patients with pre-existing kidney disease.
• The availability of antibiotic resistance data: The use of antibiotics should be guided by local resistance patterns and susceptibility data to ensure effective treatment.