What is the diagnosis and treatment for cellulitis?

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Last updated: April 2, 2025View editorial policy

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From the Guidelines

Cellulitis should be treated with an antimicrobial agent active against streptococci, and the recommended duration of antimicrobial therapy is 5 days, but treatment should be extended if the infection has not improved within this time period 1.

Diagnosis and Management

Cellulitis is a common bacterial skin infection that affects the deeper layers of skin and the subcutaneous tissue. It typically presents as a red, swollen, painful, and warm area of skin, often with poorly defined borders.

  • The diagnosis of cellulitis is primarily clinical, based on the presentation of the skin and the patient's symptoms.
  • Cultures of blood or cutaneous aspirates, biopsies, or swabs are not routinely recommended, but may be considered in certain cases, such as in patients with malignancy on chemotherapy, neutropenia, severe cell-mediated immunodeficiency, immersion injuries, and animal bites 1.

Treatment

Treatment usually involves antibiotics, with the specific regimen depending on severity.

  • For mild cases, oral antibiotics like cephalexin (500mg four times daily), dicloxacillin (500mg four times daily), or amoxicillin-clavulanate (875/125mg twice daily) for 5 days are typically effective, as supported by the Infectious Diseases Society of America guidelines 1.
  • More severe cases may require intravenous antibiotics such as cefazolin or vancomycin.
  • While taking antibiotics, elevate the affected area, rest, and apply warm compresses to improve circulation and reduce swelling.
  • Adequate pain management with acetaminophen or ibuprofen is also important.

Prevention and Complications

Cellulitis occurs when bacteria, commonly Streptococcus or Staphylococcus, enter through breaks in the skin.

  • Risk factors include skin injuries, certain skin conditions like eczema, weakened immune system, and lymphedema.
  • If left untreated, cellulitis can spread to the bloodstream and lymph nodes, potentially becoming life-threatening.
  • Seek immediate medical attention if fever develops, the affected area rapidly expands, or red streaks extend from the infected area.

Special Considerations

In severely compromised patients, broad-spectrum antimicrobial coverage may be considered, and vancomycin plus either piperacillin-tazobactam or imipenem/meropenem is recommended as a reasonable empiric regimen for severe infections 1.

From the FDA Drug Label

14 CLINICAL STUDIES 14. 1 Acute Bacterial Skin and Skin Structure Infections Adults A total of 1333 adults with acute bacterial skin and skin structure infections (ABSSSI) were randomized in two multicenter, multinational, double-blind, non-inferiority trials.

The types of ABSSSI included were cellulitis/erysipelas (41%), wound infection (29%), and major cutaneous abscess (30%) The types of ABSSSI included were cellulitis/erysipelas (50%), wound infection (30%), and major cutaneous abscess (20%)

  • Cellulitis was one of the types of acute bacterial skin and skin structure infections (ABSSSI) treated in the trials, with 41% of patients in Trial 1 and 50% of patients in Trial 2 having cellulitis/erysipelas.
  • The drug tedizolid (PO) was compared to linezolid in these trials, with the primary endpoint being early clinical response.
  • The results of these trials suggest that tedizolid (PO) may be effective in treating cellulitis, but the specific details of the response are not provided in the given text 2.

From the Research

Cellulitis Treatment

  • The treatment of cellulitis often involves the use of antibiotics, with the choice of antibiotic depending on the suspected causative organism and the severity of the infection 3, 4.
  • Studies have shown that antibiotics with activity against community-associated methicillin-resistant Staphylococcus aureus (MRSA), such as trimethoprim-sulfamethoxazole and clindamycin, are effective in treating cellulitis 3, 4.
  • A randomized non-inferiority trial found that oral antimicrobials are as effective as parenteral antimicrobials for the treatment of uncomplicated cellulitis 5.
  • A systematic review and meta-analysis found that there is no evidence to support the superiority of any one antibiotic over another, and that antibiotics with activity against MRSA do not add an advantage 6.

Antibiotic Choice

  • Cephalexin, trimethoprim-sulfamethoxazole, and clindamycin are commonly prescribed antibiotics for the treatment of cellulitis 3, 4.
  • The choice of antibiotic should be based on the suspected causative organism and the severity of the infection, as well as the patient's medical history and allergies 3, 4.
  • Clindamycin may be a more cost-effective therapy at high likelihoods of MRSA infection 4.

Route of Administration

  • Oral antimicrobials are as effective as parenteral antimicrobials for the treatment of uncomplicated cellulitis 5.
  • There is no evidence to support the use of intravenous antibiotics over oral antibiotics for the treatment of cellulitis 6.

Treatment Duration

  • The optimal duration of treatment for cellulitis is not well established, but treatment for longer than 5 days is not supported by evidence 6.
  • Further studies are needed to determine the most effective treatment duration for cellulitis 6.

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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