Cellulitis medical therapy

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Mugilan Poongkunran M.B.B.S [2]

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Overview

Beta-lactam antibiotics against Streptococcus and penicillinase-producing Staphylococcus aureus are the usual drugs of choice. Ancillary measures include elevation of the affected area to reduce fluid accumulation and cool sterile saline dressings to remove purulent debris from open wounds.

Medical Therapy

• Mostly the causative agent is streptococci (often group A, but also from other groups, such as B, C, or G) and rarely staphylococcus aureus that is associated with penetrating trauma, illicit drug use.
• Cultures of needle aspirations from inflammed skin, blood or punch biopsies are variable and not useful in the setting of mild infection and hence performed in patients with systemic toxicity, underlying comorbidities (immunodeficiency, diabetes etc) and special exposures (animal bites).
• The antibiotic selection for treatment of cellulitis depends on whether the clinical presentation is purulent or nonpurulent, as purulent cellulitis is potentially attributable to staphylococcus aureus, which should be empirically treated with Beta-lactam antibiotics. Latest reports suggest that this bacterium has acquired resistance (MRSA) and newer drugs are to be used to kill off the pathogen. Reports from the laboratory regarding the sensitivity of the pathogen is a key factor in deciding the therapy.
• Choice of the antibiotic therapy for cellulitis depends on the following factors:
  • Age of the individual: Early hospitalization and parenteral therapy are required for treatment of cellulitis in neonates, except for the mildest of cases.
  • Co-morbid conditions
  • Site of lesion
  • Severity of lesion
  • Pathogen involved (gram positive or negative and aerobic or anaerobic)
  • Strain and resistance of the pathogen
• Parenteral therapy is indicated for severely ill patients or for those unable to tolerate oral medications.
• The duration of antibiotic therapy in immunocompetent individuals is until 3 days after acute inflammation disappears.

Uncomplicated Cellulitis

• Simple infection without abscesses or drainage should be managed with empiric therapy for infection due to beta-hemolytic streptococci and methicillin sensitive staphylococcus aureus (MSSA).
• Patients allergic to penicillin drugs can be given macrolide antibiotics like azithromycin.

• According to the 2011 clinical practice guidelines, if both methicillin resistant staphylococcus aureus and Streptococcus pyogenes are possible causes, then "options include the following: clindamycin alone (A-II) or TMP-SMX or a tetracycline in combination with a β-lactam (eg, amoxicillin) (A-II) or linezolid alone (A-II)." MRSA is commonly the causative agent of cellulitis in cases presenting with abscesses. In mild cases, treatment will be TMP-SMX with doxycycline and in severe cases, the most cost effective therapy will be vancomycin.

• According to the 2005 clinical practice guidelines, which state that staphylococcus aureus is very uncommon: "Suitable agents include dicloxacillin, cephalexin, clindamycin, or erythromycin, unless streptococci or staphylococci resistant to these agents are common in the community." Another trial confirms that if purulence or diabetes are not present then coverage for staphylococcus aureus is not needed.

• A study of failed treatment concluded that failure is reduced if higher dose antibiotics are used:
  • Vancomycin at least 30 mg/kg/day
  • Clindamycin at least 10 mg/kg/day (450 mg every 8 hours)
  • TMP-SMX at least 5 mg/kg/day of trimethoprim (a single strength pill has 80 mg trimethoprim) (two double strength pills every 12 hours)
  • If levofloxacin is used for treatment, 5 days is as effective as 10 days. However, levofloxacin is ineffective against methicillin-resistant Staphylococcus aureus.

Severe Cellulitis

• In severe cases of the disease, parenteral therapy is advocated.
• Patients who do not respond to initial therapy, or with signs of systemic illness, or with recurrent infection in the setting of underlying predisposing conditions, or with risk factors for MRSA, or in communities where the prevalence of MRSA is greater, additional empiric coverage for MRSA is considered.
• Patients with a penicillin allergy can be given vancomycin and clindamycin.
• In diabetic individuals, broad coverage antibiotics are used. Carbapenams, beta-lactam antibiotics with Beta-lactamase inhibitors are given in a combined regimen for antibiotic coverage.
• The duration of therapy should be individualized depending on clinical response; 5 to 10 days is usually appropriate (7 to 10 days in neonates); longer duration of therapy may be warranted in patients with severe disease.

Empiric Therapy

▸ Click on the following categories to expand treatment regimens.

Cellulitis   ▸  Infants 0-4 weeks of age   ▸  Infants <1 week of age   ▸  Infants ≥1 week of age Non-purulent Cellulitis   ▸  Adults   ▸  Children age >28 days Purulent Cellulitis   ▸  Adults   ▸  Children age >28 days

Infants 0 to 4 weeks of age Parental Regimen ▸ Vancomycin 15 mg/kg IV q24h PLUS ▸ Cefotaxime 50 mg/kg IV q12h OR ▸ Gentamicin 2.5 mg/kg IV q18-24h Infants 0 to 4 weeks of age Oral Regimen ▸ Clindamycin 5 mg/kg orally q12h OR ▸ Linezolid 10 mg/kg orally q8-12h Infants <1 week of age (BW 1200 to 2000 g) Parental Regimen ▸ Vancomycin 10 to 15 mg/kg IV q12-18h PLUS ▸ Cefotaxime 50 mg/kg IV q12h OR ▸ Gentamicin 2.5 mg/kg IV q12h Infants <1 week of age (BW 1200 to 2000 g) Oral Regimen ▸ Clindamycin 5 mg/kg orally q12h OR ▸ Linezolid 10 mg/kg orally q8-12h Infants <1 week of age (BW >2000 g) Parental Regimen ▸ Vancomycin 10 to 15 mg/kg IV q8-12h PLUS ▸ Cefotaxime 50 mg/kg IV q8-12h OR ▸ Gentamicin 2.5 mg/kg IV q12h Infants <1 week of age (BW >2000 g) Oral Regimen ▸ Clindamycin 5 mg/kg orally q8h OR ▸ Linezolid 10 mg/kg orally q8-12h Infants ≥1 week of age (BW 1200 to 2000 g) Parental Regimen ▸ Vancomycin 10 to 15 mg/kg IV q8-12h PLUS ▸ Cefotaxime 50 mg/kg IV q8h OR ▸ Gentamicin 2.5 mg/kg IV q8-12h Infants ≥1 week of age (BW 1200 to 2000 g) Oral Regimen ▸ Clindamycin 5 mg/kg orally q8h OR ▸ Linezolid 10 mg/kg orally q8h Infants ≥1 week of age (BW > 2000 g) Parental Regimen ▸ Vancomycin 10 to 15 mg/kg IV q6-8h PLUS ▸ Cefotaxime 50 mg/kg IV q6-8h OR ▸ Gentamicin 2.5 mg/kg IV q8h Infants ≥1 week of age (BW > 2000 g) Oral Regimen ▸ Clindamycin 5 mg/kg orally q6h OR ▸ Linezolid 10 mg/kg orally q8h

Parental Regimen Preferred Regimen ▸ Oxacillin 2g IV q4h OR ▸ Nafcillin 2g IV q4h Alternative Regimen (penicillin-allergic patients) ▸ Cefazolin 1-2 g IV q8h (without immediate hypersensitivity reactions) OR ▸ Clindamycin 600 mg IV q8h (with immediate hypersensitivity reactions) Oral Regimen Preferred Regimen ▸ Dicloxacillin 500 mg orally q6h Alternative Regimen (penicillin-allergic patients) ▸ Cephalexin 500 mg orally q6h (without immediate hypersensitivity reactions) OR ▸ Doxycycline 100 mg orally q12h OR ▸ Minocycline 100 mg orally q12h OR ▸ Trimethoprim-sulfamethoxazole 1 or 2 double-strength tablets orally q12h OR ▸ Clindamycin 300–450 mg orally q8h

Parental Regimen Preferred Regimen ▸ Oxacillin 100-150 mg/kg per day IV in 4 doses OR ▸ Nafcillin 100-150 mg/kg per day IV in 4 doses Alternative Regimen (penicillin-allergic patients) ▸ Cefazolin 50 mg/kg per day IV in 3 doses (without immediate hypersensitivity reactions) OR ▸ Clindamycin 25-40 mg/kg per day IV in 3 doses(with immediate hypersensitivity reactions) OR ▸ Trimethoprim-sulfamethoxazole 8–12 mg/kg IV in 4 doses Oral Regimen Preferred Regimen ▸ Dicloxacillin 25 mg/kg per day orally in 4 doses Alternative Regimen (penicillin-allergic patients) ▸ Cephalexin 25 mg/kg per day orally in 4 doses(without immediate hypersensitivity reactions) OR ▸ Clindamycin 10-20 mg/kg per day orally in 4 doses OR ▸ Trimethoprim-sulfamethoxazole 8–12 mg/kg orally in 2 doses Parental Regimen Preferred Regimen ▸ Vancomycin 30 mg/kg/dose IV q12h Alternative Regimen ▸ Linezolid 600 mg IV q12h OR ▸ Clindamycin 600 mg IV q8h OR ▸ Daptomycin 4 mg/kg IV q24h Oral Regimen Preferred Regimen ▸ Linezolid 600 mg orally q12h Alternative Regimen ▸ Clindamycin 300 to 450 mg q8h OR ▸ Linezolid 600 mg orally q12h OR ▸ Minocycline 100 mg orally q12h OR ▸ Doxycycline 100 mg orally q12h OR ▸ Trimethoprim-sulfamethoxazole 1 or 2 double-strength tablets orally q12h Parental Regimen Preferred Regimen ▸ Vancomycin 40 mg/kg/day IV in 4 divided doses Alternative Regimen ▸ Linezolid 10 mg/kg IV q12h OR ▸ Clindamycin 25–40 mg/kg/day IV in 3 divided dose OR ▸ Trimethoprim-sulfamethoxazole 8–12 mg/kg/day (based on the trimethoprim component) IV in 4 divided doses Oral Regimen Preferred Regimen ▸ Linezolid 10 mg/kg orally q12h Alternative Regimen ▸ Clindamycin 10-20 mg/kg per day orally divided in 3 doses OR ▸ Trimethoprim-sulfamethoxazole 8-12 mg trimethoprim component/kg per day orally divided in 2 doses

Note:

• Treatment of cellulitis in neonates usually requires hospitalization and parenteral therapy. Oral therapy is given for completion of the treatment when the patogen is unknown.
• Optimal dose should be based on determination of serum concentrations.
• The above antibiotic regimen is NOT for initial empirical treatment of infections involving the face.
• Dose alteration for renal insufficiency may be needed in case of cephalosporins.
• Clindamycin is an alternate therapy for patients at risk of severe hypersensitivity reaction to penicillins and cephalosporins.
• Doxycycline is NOT recommended for children <8 years of age.
• Studies have shown an increase in treatment failure with TMP-SMX compared to other agents for cellulitis in children, reflecting TMP-SMX less action against Group A streptococcus.

Special Cases

Orbital Cellulitis

• Treatment regimens are usually empiric and designed to address the usual pathogens like Streptococcus pneumoniae, Hemophilus influenzae, Moraxella catarrhalis, Staphylococcus aureus, anaerobes (when intracranial extension is suspected), group A streptococci, and sometimes gram negative bacilli because, in the absence of surgical intervention, reliable culture results are difficult to obtain.

▸ Click on the following categories to expand treatment regimens.

Orbital Cellulitis   ▸  Usual pathogens   ▸  MRSA

Usual pathogens Preferred Regimen ▸ Nafcillin 2 gm IV q4h PLUS ▸ Ceftriaxone 2 gm IV q24h PLUS ▸ Metronidazole 1 gm IV q12h Alternative Regimen ▸ Vancomycin 1 gm IV q12h PLUS ▸ Levofloxacin 750 mg IV once daily PLUS ▸ Metronidazole 1 gm IV q12h MRSA Preferred Regimen ▸ Vancomycin 1 gm IV q12h PLUS ▸ Ceftriaxone 2 gm IV q24h PLUS ▸ Metronidazole 1 gm IV q12h Alternative Regimen ▸ Daptomycin 6 mg/kg IV q24h PLUS ▸ Levofloxacin 750 mg IV once daily OR ▸ Ceftriaxone 2 gm IV q24h PLUS ▸ Metronidazole 1 gm IV q12h

• Bite Wounds (Mammalian).
  • Bite wounds suffered from a mammal often contain polymicrobial sources that are anaerobic in nature.
  • Mild cases can be treated with amoxicillin and clavulanate, and in cases of penicillin allergy cotrimoxazole along with metronidazole is used.
  • In severe cases, piperacillin and tazobactum are used.

• Acquatic punctures and lacerations.
  • This is seen mainly in professional swimmers and divers both in freshwater and in brackish water.
  • Failure to recognize these wounds and delay treatment may cause a larger morbidity.
  • Wounds in fresh water are treated with doxycycline and ceftazidime (or fluroquinolones).
  • Wounds in brackish water are treated with ceftazidime and levofloxacin.

Non-Antibiotic Therapy

• Elevation of the affected area facilitates gravity drainage of edema and inflammatory substances. Compressive stockings and diuretic therapy may help patients with edema.
• The skin should be sufficiently hydrated to avoid dryness and cracking without maceration.