Cellulitis

[Section Outline]

Description
Etiology

Author:

JohnMahoney

DoloresGonthier

Description

Acute, spreading erythematous superficial infection of skin and SC tissues:
- Nonpurulent SSTI (skin and soft tissue infection) = uncomplicated cellulitis
- Purulent SSTI = cellulitis with purulent component is covered in “Abscess”
- Extension into deeper tissues can result in necrotizing soft tissue infection
Progressive spread of erythema, warmth, pain, and tenderness
Predisposing factors:
- Lymphedema
- Tinea pedis or other toe web abnormalities
- Open wounds
- Pre-existing skin lesion (furuncle)
- Prior trauma or surgery
- Retained foreign body
- Vascular or immune compromise
- Injection drug use
- Recurrent SSTI

Etiology

Uncomplicated cellulitis (nonpurulent SSTI):
- Group A streptococci
- Methicillin-sensitive Staphylococcus aureus (MSSA)
- Methicillin-resistant S. aureus (MRSA)
- Risk factors for Staph infection (MSSA and MRSA):
  - Recent hospital or long-term care admission
  - Recent surgery
  - Children
  - Soldiers
  - Incarcerated persons
  - Athletes in contact sports
  - Injection drug use
  - Men who have sex with men
  - Dialysis treatments and catheters
  - History of penetrating trauma
- Additional risk factors for MRSA infection:
  - Prior MRSA infection
  - MRSA colonization
  - Area of high MRSA incidence
  - Close contact with MRSA patient
Extremity cellulitis after lymphatic disruption:
- Nongroup A β-hemolytic streptococci (groups C, B, G)
Cellulitis in diabetics:
- Can be polymicrobial with S. aureus, streptococci, gram-negative bacteria, and anaerobes, especially when associated with skin ulcers
Periorbital cellulitis:
- Strep and Staph
Buccal cellulitis:
- Polymicrobial with anaerobic oral flora, associated with intraoral laceration or dental abscess
Less common causes:
- Clostridia
- Anthrax
- Pasteurella multocida - common after cat and dog bites
- Eikenella corrodens - human bites
- Pseudomonas aeruginosa:
  - Hot-tub folliculitis - self-limited
  - Foot puncture wound
  - Ecthyma gangrenosum in neutropenic patients
- Erysipelothrix species - saltwater fish, poultry, meat, or hide hand lers
- Aeromonas hydrophila - freshwater swimming
- Vibrio species - seawater or raw seafood

Pediatric Considerations
Facial cellulitis in children: Streptococcus pneumoniae H. influenzae type B, although incidence significantly declining since introduction of HIB vaccine Perianal cellulitis: Group A streptococci Associated or antecedent pharyngitis or impetigo Neonates: Group B streptococci

Diagnosis ⬆ ⬇

[Section Outline]

Signs and Symptoms
Essential Workup
Diagnostic Tests & Interpretation
Differential Diagnosis

Signs and Symptoms

Common to all syndromes:
- Pain, tenderness, warmth
- Erythema
- Edema or induration
- Fever/chills
- Tender regional lymphadenopathy
- Lymphangitis
- Accompanying SC abscess possible
- Superficial vesicles
Buccal cellulitis:
- Toothache, sore throat, or facial swelling
- Progressive extension into soft tissues of neck with fever, erythema, neck swelling, and dysphagia

Pediatric Considerations
Facial cellulitis in children: Erythema and swelling of the cheek and eyelid Rapidly progressive Usually unilateral Upper respiratory tract symptoms Risk for cavernous sinus thrombosis and permanent optic nerve injury Perianal cellulitis: Erythema and pruritus extending from the anus several centimeters onto adjacent skin Pain on defecation Blood-streaked stools Purulent secretions

History

Staph etiology: Indolent progression, post-trauma
Strep etiology: More acute, concomitant nausea from toxin, pre-existing lymphedema

Physical Exam

Staph etiology: Focal abscess or pustule with: fluctuance, yellow or white center, central point or “head,” or draining pus, folliculitis-looking rash, associated with trauma
Strep etiology: Sharply demarcated borders, lymphangitis
Search for infection source
Identify toe web abnormalities
Evaluate for vascular sufficiency

Essential Workup

Cellulitis is a clinical diagnosis

Diagnostic Tests & Interpretation

Lab

WBC may be helpful to guide intensity of treatment but does not aid with diagnosis
Routine aspiration of leading edge not recommended
Culture wound or aspirate if: Pustular collection present; suspect an unusual or resistant pathogen; or initial therapy is not successful
Blood culture:
- Usually negative in uncomplicated cellulitis
- May identify organism in patients with:
  - Lymphedema
  - Buccal or periorbital cellulitis
  - Saltwater or freshwater source
  - Systemic symptoms

Imaging

Plain radiographs may reveal abscess formation, SC gas, or foreign bodies:
- Extension to bone (osteomyelitis) not visualized early on plain radiographs
Extremity vascular imaging (Doppler US) can help rule out deep venous thrombosis (DVT)
US useful for diagnosing abscess if physical exam is equivocal or if there is a broad area of cellulitis
- In cellulitis, may see characteristic “cobblestone” appearance and thickening of SC layer, both due to edema
CT or MRI can help rule out necrotizing fasciitis

Differential Diagnosis

Stasis dermatitis
Necrotizing fasciitis
Lymphangitis or lymphadenitis
Thrombophlebitis or DVT
Insect bite
Allergic reaction
Acute gout or pseudogout
Ruptured Baker cyst
Herpetic whitlow
Neoplasm
Phytophotodermatitis
Erythema chronicum migrans lesion of Lyme disease
Differential diagnosis of facial cellulitis:
- Allergic angioedema
- Conjunctivitis
- Contusion

Pediatric Considerations
Differential diagnosis of perianal cellulitis: Cand ida intertrigo Psoriasis Pinworm infection Child abuse Behavioral problem Inflammatory bowel disease

Treatment ⬆ ⬇

[Section Outline]

Initial Stabilization/Therapy
ED Treatment/Procedures
Medication

Initial Stabilization/Therapy

Airway compromise possible with deep extension of facial or neck cellulitis
Monitor and support blood pressure/ventilation in sepsis syndrome
Assess severity of systemic symptoms including SIRS criteria (Systemic Inflammatory Response Syndrome)
- SIRS criteria:
  - Temperature >38°C or <36°C
  - HR > 90/min
  - RR > 20/min
  - WBC count > 12,000 or < 4,000/mm³

ED Treatment/Procedures

General treatments:
- Cool compresses for comfort
- Analgesics
- Extremity elevation
- Treat tinea pedis or other toe web abnormality
Principles of cellulitis care:
- Consider local prevalence of resistant pathogens in addition to usual causes
- Usual outpatient treatment:
  - 5-10 days of antibiotics
  - Follow-up in 48-72 hr to assess improvement
- If there is suspicion that Staph could be a causative agent, antibiotics should cover both MSSA and MRSA
  - This suspicion should be based on the clinical exam, assessments of risk factors, and the severity of systemic symptoms (SIRS criteria)
Uncomplicated cellulitis = Nonpurulent SSTI
- Outpatient:
  - Cephalexin
  - Alternatives: dicloxacillin, clindamycin
- Inpatient:
  - IV nafcillin or IV cefazolin
  - Alternative: IV clindamycin
MRSA treatment: add the following if suspicion that MRSA is etiologic agent
- Outpatient
  - TMP/SMX
  - Alternative: Doxycycline
- Inpatient:
  - IV vancomycin
  - Alternative: IV linezolid
Cellulitis with severe systemic symptoms:
- Defined as ≥2 SIRS criteria plus hypotension or immune compromise or rapid disease progression
- IV vancomycin plus IV piperacillin/tazobactam
Extremity cellulitis after lymphatic disruption:
- Same as uncomplicated cellulitis
Cellulitis in diabetics:
- Outpatient:
  - Cephalexin + TMP/SMX
- Inpatient:
  - IV imipenem cilastatin or equivalent + IV vancomycin or IV/PO linezolid
Periorbital cellulitis:
- Outpatient: Amoxicillin/clavulanate
- Inpatient: IV ampicillin/sulbactam
Buccal cellulitis in adults:
- Drainage of odontogenic source is essential
- Outpatient: Amoxicillin/clavulanate
- Inpatient: IV ampicillin/sulbactam + IV vancomycin
- Alternative: Clindamycin
Facial cellulitis in children:
- IV ceftriaxone
Perianal cellulitis:
- Outpatient: Penicillin VK
- Inpatient: IV penicillin G (aqueous)
Animal or human bite:
- Amoxicillin/clavulanate
Foot puncture wound:
- Oral or IV ciprofloxacin or IV ceftazidime

Medication

Amoxicillin/clavulanate: 875 mg PO b.i.d or 500 mg PO t.i.d (peds: 7:1 formulation:45 mg/kg/24 hr PO q12h)
Ampicillin/sulbactam: 1.5-3 g (peds: 100-300 mg/kg/24 hr up to 40 kg; over 40 kg give adult dose) IV q6h
Ceftazidime: 1-2 g (peds: 150-200 mg/kg/24 hr; max. 6 g/24 hr; use sodium formulation in peds) IV q8h
Ceftriaxone: 1-2 g (peds: 50-100 mg/kg/24 hr) IV daily
Cefazolin: 1-1.5 g (peds: 50-100 mg/kg/24 hr; max 6 g/24 hr) IV q8h
Cephalexin: 500 mg (peds: 25-50 mg/kg/24 hr; max 4g/24 hr) PO q.i.d
Ciprofloxacin: (Adult only) 500-750 mg PO b.i.d or 400 mg IV q12hr
Clindamycin: 300-450 mg (peds: 30-40 mg/kg/24 hr) PO q6h; 600 mg (peds: 25-40 mg/kg/24 hr) IV q8h
Dicloxacillin: 250-500 mg (peds: 12.5-25 mg/kg/24 hr) PO q6h
Doxycycline: 100 mg PO b.i.d for adults
Imipenem cilastatin: 500 mg (peds: 60-100 mg/kg/24 hr, max 4 g/24 hr) IV q6hr; max. 4 g/24 hr or 50 mg/kg/24 hr, whichever is less
Linezolid: 600 mg PO or IV q12hr (peds <12 yo: 30 mg/kg/24 hr PO or IV q8-12h)
Nafcillin: 1-2 g IV q4hr (peds: 100-200 mg/kg/24 hr IV q6h); max 12 g/24 hr
Penicillin VK: 250-500 mg (peds: 25-75 mg/kg/24 hr) PO q6hr
Penicillin G (aqueous): 2-4 million units (peds: 150,000-300,000 units/kg/24 hr; max 12-20 million units/days) IV q4-6 hr
Piperacillin/tazobactam:3.375 g (peds: 300 mg/kg/24 hr. Use adult dose over 40 kg) IV q6h
Trimethoprim/sulfamethoxazole (TMP/SMX): 1-2 DS tabs (peds: 8-12 mg/kg/24 hr based on TMP component) PO q12hr
Vancomycin: 30-40 mg/kg/24 hr IV q8-12hr, do not exceed 4 g/24 hr or 2 g/dose (peds: 40 mg/kg/24 hr IV q6hr; dosing adjustments required younger than age 5 yr); check serum levels

Follow-Up ⬆ ⬇

[Section Outline]

Disposition
Follow-up Recommendations

Disposition

Admission Criteria

Toxic appearing
Signs of systemic illness
Tissue necrosis
History of immune suppression
Concurrent chronic medical illnesses
Unable to take oral medications
Unreliable patients
Failed outpatient treatment

Discharge Criteria

Mild infection in a nontoxic-appearing patient
Able to take oral antibiotics
No history of immune suppression or concurrent medical problems
No hand or face involvement
Has adequate follow-up within 24-48 hr

Follow-up Recommendations

Follow-up within 24-48 hr
Sooner if worsening symptoms, including new or worsening lymphangitis, increasing area of redness, worsening fever
Outline the border of erythema before discharge to aid in assessing response to therapy

Pearls and Pitfalls ⬆ ⬇

Strep and Staph are the most common causes
If suspect Staph infection, must include MRSA coverage
Suspect MRSA in unresponsive infections
Consider admission and IV therapy for patients with 1 or more SIRS criteria
Use clinical suspicion and ultrasound to avoid missing an abscess

Additional Reading ⬆ ⬇

LiuC, BayerA, CosgroveSE, et al. Clinical practice guidelines by the Infectious Diseases Society of America for the treatment of methicillin-resistant Staphylococcus aureus infections in adults and children . Clin Infect Dis. 2011;52:e18-e55.
MoranGJ, KrishnadasanA, MowerWR, et al. Effect of cephalexin plus trimethoprim sulfamethoxazole vs cephalexin alone on clinical cure of uncomplicated cellulitis: A rand omized clinical trial . JAMA. 2017;317:2088-2096.
PasternackMS, SwartzMN. Cellulitis, necrotizing fasciitis and subcutaneous tissue infections. In: BennettJE, DolinR, BlaserMJ, eds. Mand ell, Douglas and Bennett's Principles and Practice of Infectious Diseases. 8th ed.New York: Elsevier/Churchill Livingstone; 2014:1194-1215.
RaffAB, KroshinskyD. Cellulitis: A review . JAMA. 2016;316:325-337.
StevensDL, BisnoAL, ChanbersHF, et al. Practice guidelines for the diagnosis and management of skin and soft tissue infections: 2014 Update by the Infectious Diseases Society of America . Clin Infect Dis. 2014;59:147-159.

See Also (Topic, Algorithm, Electronic Media Element)

Codes ⬆

ICD9

682.3 Cellulitis and abscess of upper arm and forearm
682.6 Cellulitis and abscess of leg, except foot
682.9 Cellulitis and abscess of unspecified sites
682.0 Cellulitis and abscess of face
682.1 Cellulitis and abscess of neck
682.2 Cellulitis and abscess of trunk
682.4 Cellulitis and abscess of hand , except fingers and thumb
682.5 Cellulitis and abscess of buttock
682.7 Cellulitis and abscess of foot, except toes
682.8 Cellulitis and abscess of other specified sites
682 Other cellulitis and abscess

ICD10

H05.019 Cellulitis of unspecified orbit
L03.90 Cellulitis, unspecified
L03.119 Cellulitis of unspecified part of limb
L03.211 Cellulitis of face
L03.011 Cellulitis of right finger
L03.012 Cellulitis of left finger
L03.019 Cellulitis of unspecified finger
L03.01 Cellulitis of finger
L03.031 Cellulitis of right toe
L03.032 Cellulitis of left toe
L03.039 Cellulitis of unspecified toe
L03.03 Cellulitis of toe
L03.111 Cellulitis of right axilla
L03.112 Cellulitis of left axilla
L03.113 Cellulitis of right upper limb
L03.114 Cellulitis of left upper limb
L03.115 Cellulitis of right lower limb
L03.116 Cellulitis of left lower limb
L03.11 Cellulitis of other parts of limb
L03.1 Cellulitis and acute lymphangitis of other parts of limb
L03.221 Cellulitis of neck
L03.311 Cellulitis of abdominal wall
L03.312 Cellulitis of back [any part except buttock]
L03.313 Cellulitis of chest wall
L03.314 Cellulitis of groin
L03.315 Cellulitis of perineum
L03.316 Cellulitis of umbilicus
L03.317 Cellulitis of buttock
L03.319 Cellulitis of trunk, unspecified
L03.31 Cellulitis of trunk
L03.811 Cellulitis of head [any part, except face]
L03.818 Cellulitis of other sites
L03.81 Cellulitis of other sites

SNOMED

128045006 cellulitis (disorder)
449671007 Cellulitis of upper limb (disorder)
449710006 Cellulitis of lower limb (disorder)
194005002orbital cellulitis (disorder)
123951002 cellulitis of skin (disorder)
200652002 cellulitis of face (disorder)
239162003 Wound cellulitis (disorder)
30584002 Cellulitis of back, except buttock (disorder)
46876003 Cellulitis of trunk (disorder)

section name header

Basics ⬇

Pediatric Considerations

Diagnosis ⬆ ⬇

Pediatric Considerations

History

Physical Exam

Lab

Imaging

Pediatric Considerations

Treatment ⬆ ⬇

Follow-Up ⬆ ⬇

Admission Criteria

Discharge Criteria

Pearls and Pitfalls ⬆ ⬇

Additional Reading ⬆ ⬇

Codes ⬆