Is vancomycin (Vanc) monotherapy sufficient for a recently hospitalized patient presenting with concern for cellulitis, or should additional antibiotics be added to the treatment regimen?

From the Guidelines

For a patient recently hospitalized with cellulitis, vancomycin alone may not be sufficient, and the optimal regimen depends on several factors, including the severity of the infection and the presence of comorbidities or risk factors for MRSA or gram-negative organisms. For empiric treatment of moderate to severe cellulitis requiring hospitalization, I recommend combination therapy with vancomycin (15-20 mg/kg IV every 8-12 hours, adjusted based on renal function and targeting trough levels of 15-20 μg/mL) plus either piperacillin-tazobactam (4.5g IV every 6-8 hours) or cefepime (2g IV every 8-12 hours) 1. This combination provides coverage for both MRSA (from vancomycin) and gram-negative organisms including Pseudomonas (from the beta-lactam). Monotherapy with vancomycin alone would be appropriate only if you're confident the infection is caused by gram-positive organisms, particularly MRSA. Consider adding clindamycin (600-900mg IV every 8 hours) if there are signs of toxin production such as rapidly spreading erythema or systemic toxicity. Once culture results return, de-escalate therapy accordingly. The rationale for broader initial coverage is that cellulitis can be polymicrobial, particularly in patients with comorbidities, immunosuppression, or specific risk factors like diabetes, vascular disease, or recent trauma/surgery to the affected area. Key factors to consider when selecting an antibiotic regimen include the severity of the infection, the presence of comorbidities or risk factors for MRSA or gram-negative organisms, and the results of culture and susceptibility testing 1. In general, the duration of antibiotic therapy for cellulitis should be individualized based on the patient's clinical response, but a course of 5-7 days is often recommended 1.

Some key points to consider when treating cellulitis include:

• The importance of covering for both MRSA and streptococci in patients with moderate to severe cellulitis requiring hospitalization
• The need to consider broader coverage, including gram-negative organisms, in patients with comorbidities or risk factors for these infections
• The importance of individualizing the duration of antibiotic therapy based on the patient's clinical response
• The need to de-escalate therapy once culture results return to minimize the risk of antibiotic resistance and side effects. It's also important to note that the treatment of cellulitis should be guided by the most recent and highest-quality evidence, and that the recommendations may vary depending on the specific clinical scenario and the patient's individual needs 1.

From the Research

Treatment of Cellulitis

• The majority of non-purulent, uncomplicated cases of cellulitis are caused by β-hemolytic streptococci or methicillin-sensitive Staphylococcus aureus 2.
• Appropriate targeted coverage of this pathogen with oral antibiotics such as penicillin, amoxicillin, and cephalexin is sufficient 2.
• Vancomycin (Vanc) is typically used to treat methicillin-resistant Staphylococcus aureus (MRSA) infections, but coverage for non-purulent cellulitis is generally not recommended 2.

Considerations for Antibiotic Selection

• Antibiotic selection is determined by patient history and risk factors, severity of clinical presentation, and the most likely microbial culprit 3.
• The history and physical examination are helpful in differentiating cellulitis and abscess in many cases, and point-of-care ultrasound can be a useful tool in unclear cases 4.
• Treatment for cellulitis typically involves a penicillin or cephalosporin, and treatment of abscesses is incision and drainage 4.

Alternative Antibiotic Options

• Ceftriaxone is a third-generation cephalosporin with a broad spectrum of activity against Gram-positive and Gram-negative aerobic, and some anaerobic, bacteria 5.
• Ceftriaxone has been effective in treating infections due to other 'difficult' organisms such as multidrug-resistant Enterobacteriaceae 5.
• However, ceftriaxone has some activity against Pseudomonas aeruginosa, but it cannot be recommended as sole antibiotic therapy in pseudomonal infections 5.