What is the best treatment approach for a patient with multiple myeloma (MM) presenting with a cutaneous rash and cellulitis on the buttock?

Treatment of Cellulitis in a Patient with Multiple Myeloma

For a patient with multiple myeloma presenting with cellulitis on the buttock, vancomycin plus either piperacillin-tazobactam or imipenem/meropenem is recommended as empiric therapy due to the immunocompromised status of the patient. 1

Assessment and Classification

• Cellulitis in immunocompromised patients, such as those with multiple myeloma, requires special consideration due to increased risk of severe infection and atypical pathogens 1
• Blood cultures should be obtained before starting antibiotics in patients with malignancy on chemotherapy, as recommended for immunocompromised patients 1
• The severity of cellulitis should be assessed based on systemic signs of infection, with multiple myeloma patients typically falling into the "severe nonpurulent" category due to their immunocompromised status 1

Antibiotic Selection

• For immunocompromised patients with cellulitis, broad-spectrum antimicrobial coverage is recommended 1
• Vancomycin plus either piperacillin-tazobactam or imipenem/meropenem is the recommended empiric regimen for severe infections in immunocompromised hosts 1
• This combination provides coverage against both MRSA and streptococci (vancomycin) as well as gram-negative and anaerobic organisms (piperacillin-tazobactam or imipenem/meropenem) 1
• Daptomycin (4 mg/kg IV q24h) is an alternative to vancomycin for coverage of gram-positive organisms including MRSA, with comparable efficacy in clinical trials 2

Treatment Setting and Duration

• Hospitalization is recommended for cellulitis in severely immunocompromised patients, such as those with multiple myeloma 1
• The recommended duration of antimicrobial therapy is 5 days initially, but treatment should be extended if the infection has not improved within this time period 1
• Some patients may require up to 10-14 days of therapy depending on clinical response 1

Adjunctive Measures

• Elevation of the affected area is recommended to reduce edema and promote healing 1
• Systemic corticosteroids could be considered in non-diabetic adult patients with cellulitis to reduce inflammation, though this must be balanced against the risk of further immunosuppression in a multiple myeloma patient 1
• Treatment of predisposing factors is essential to prevent recurrence 1

Special Considerations for Multiple Myeloma Patients

• Multiple myeloma patients have a 7-fold higher risk of bacterial infections compared to the general population 1
• Infection is the main cause of death in approximately 22% of multiple myeloma patients within the first year of diagnosis 1
• The increased susceptibility to infections in multiple myeloma results from disease-related immune dysfunction, including B-cell dysfunction and abnormalities of dendritic, T, and NK cells 1
• Treatment-related immunosuppression further increases infection risk 1

Monitoring and Follow-up

• Close monitoring for clinical improvement is essential, with adjustment of antibiotics based on culture results if available 1
• If the cellulitis worsens despite appropriate antibiotics, consider deeper or necrotizing infection requiring surgical evaluation 1
• Monitor renal function closely, as both vancomycin and multiple myeloma can cause renal impairment 3

Common Pitfalls and Caveats

• Avoid rapid infusion of vancomycin, which can cause hypotension and "red man syndrome" - administer over at least 60 minutes 3
• Monitor for vancomycin-associated nephrotoxicity, especially in multiple myeloma patients who may already have renal impairment 3
• Consider the possibility of recurrent infection, which may require investigation for local causes and decolonization regimens 1
• Be vigilant for signs of deeper infection or sepsis, which may develop more rapidly in immunocompromised patients 1