Cellulitis

Description of Medical Condition

An acute, spreading infection of the dermis and subcutaneous tissue. Several entities are recognized:

• Cellulitis of the extremities — characterized by an expanding, red, swollen, tender or painful plaque with an indefinite border that may cover a wide area
• Recurrent cellulitis of the leg after saphenous venectomy — patients have an acute onset of swelling, erythema of the legs arising months to years after coronary artery bypass. (Surgery using lower extremity veins for bypass grafts.)
• Dissecting cellulitis of the scalp — recurrent painful, fluctuant dermal and subcutaneous nodules
• Facial cellulitis in adults — a rare event. Patients usually develop pharyngitis, followed by high fever, rapidly progressive anterior neck swelling, tenderness and erythema associated with dysphagia.
• Facial cellulitis in children — potentially serious. Swelling and erythema of the cheek develop rapidly, usually unilateral.
• Perianal cellulitis — bright perianal erythema extending from the anal verge approximately 2 to 3 cm onto the surrounding perianal skin
• Pseudomonas cellulitis — may be a localized phenomenon or it may occur during pseudomonas septicemia

System(s) affected: Skin/Exocrine

Genetics: No known genetic pattern

Incidence/Prevalence in USA: Unknown

Predominant age:

• Perianal cellulitis — principally in children
• Facial cellulitis — in adults, usually older than 50 years. In children, between 6 months and three years.

Predominant sex: Male = Female (perianal cellulitis more common in boys)

Medical Symptoms and Signs of Disease

General

• Local tenderness
• Pain
• Erythema
• Malaise
• Fever, chills
• Involved area is red, hot, and swollen
• Borders of the area are not elevated and not demarcated
• Regional lymphadenopathy is common

Recurrent cellulitis

• Same as above
• Edema
• High fever, chills and toxicity

Dissecting cellulitis of the scalp

• Purulent drainage from burrowing interconnecting abscesses

Facial cellulitis in adults

• Malaise
• Anorexia
• Vomiting
• Itching
• Burning
• Dysplasia
• Anterior neck swelling

Facial cellulitis in children

• Irritability
• Upper respiratory tract infection symptoms

Perianal cellulitis

• Intense perianal erythema
• Pain on defecation
• Blood streaked stools
• Perianal pruritus

What Causes Disease?

By site

• Cellulitis of the extremities: Group A streptococcus, Staphylococcus aureus
• Recurrent cellulitis of the leg: Non-group A beta hemolytic Streptococci (group C,G,B)
• Dissecting cellulitis of the scalp: Staphylococcus aureus
• Facial cellulitis in adults: H. influenzae type B
• Facial cellulitis in children: H. influenzae type B, over 3 years with portal of entry:
  • staphylococcal and streptococcal
• Synergetic necrotizing cellulitis: Mixed aerobic-anaerobic flora
• Intravenous drug use: Staphylococcus aureus. Streptococci, Enterobacteriaceae, Pseudomonas, Fungi
• Synergetic necrotizing cellulitis: Mixed aerobic-anaerobic flora

Specific diseases

• Diabetes mellitus: Staphylococcus aureus.

Streptococci, Enterobacteriaceae, Anaerobes

• Human bites: Eikenella corrodens
• Animal bites (cat and dog): Staphylococci, Pasteurella multocida

Patient groups

Oneonates: Group B streptococcus Olmmunocompromised

• Bacteria (Serratia, Proteus and other Enterobacteriaceae)
• Fungi (Cryptococcus neoformans)
• Atypical mycobacterium
• Children with nephrotic syndrome: E. coli
• Environmental and occupational exposures
• Erysipelothrix rhusiopathiae

Vibrio species

• Aeromonas hydrophilia

Rare causes

• Anaerobic
• Clostridium perfringens (gas forming cellulitis)
• Tuberculosis
• Syphilitic gumma
• Fungal: Mucormycosis, Aspergillosis

Risk Factors

General

• Previous trauma (laceration, puncture, human or animal bite)
• Underlying skin lesion (furuncle, ulcer)
• Surgical wound
• Recurrent cellulitis
• Post coronary artery bypass in patients whose saphenous veins have been removed
• Lower extremity lymphedema secondary to a) radical pelvic surgery b) radiation therapy c) neoplastic involvement of pelvic lymph nodes
• Mastectomy
• Diabetes mellitus
• Intravenous drug use
• Immunocompromised host
• Burns
• Environmental and occupational factors

Diagnosis of Disease

Differential Diagnosis

Perianal cellulitis OCandida intertrigo

• Psoriasis
• Pinworm infection
• Inflammatory bowel disease
• Behavioral problem
• Child abuse

Others

• Acute gout
• Fasciitis/myositis
• Mycotic aneurysm
• Ruptured Baker’s cyst
• Thrombophlebitis
• Osteomyelitis OHerpetic whitlow
• Cutaneous diphtheria
• Pseudogout

Laboratory

• Aspirates from the point of maximum inflammation. Yield a 45% positive culture rate as compared to a 5% from leading edge culture.
• Blood cultures — potential pathogens isolated in 25% of patients
• Mild leucocytosis with a left shift
• A mildly elevated sedimentation rate
• CBC

Drugs that may alter lab results: Previous antibiotic therapy may alter the results

Disorders that may alter lab results: N/A

Pathological Findings

Biopsy of skin shows marked infiltration of the dermis with eosinophils and inflammatory changes

Special Tests

• Serial serological testing with antistreptolysin 0, anti-deoxyribonuclease B, and anti-hyaluronidase tests may be successful in diagnosing cellulitis caused by group A, C, or G hemolytic streptococci
• Sinus drainage and culture of aspirate

Imaging

Gas forming cellulitis

• Plain x-rays show gas bubbles in the soft tissue
• CT shows gas and myonecrosis

Diagnostic Procedures

• Skin biopsy
• Lumbar puncture should be considered for all children with H. influenzae type B cellulitis

Treatment (Medical Therapy)

Appropriate Health Care

Outpatient for mild cases, inpatient for severe infections

General Measures

• Immobilization and elevation of the involved limb to reduce swelling may be needed in H. influenzae type B
• Sterile saline dressings to decrease local pain
• Moist heat to localize the infection
• Cool aluminum acetate (Burow’s solution) compresses for pain relief

Surgical Measures

• Debridement for gas/purulent collections
• Intubation or tracheotomy may be needed for cellulitis of the head or neck
• Hand infections — wide filleting incision in necrotizing cellulitis

Activity

Ambulatory in mild infection; bedrest in severe infection

Diet

Regular diet

Patient Education

• Good skin hygiene
• Avoid skin traumas
• Report early skin changes to physician

Medications (Drugs, Medicines)

Drug(s) of Choice

Treat 10-30 days. Guided by culture results whenever possible.

• Mild early suspected streptococcal etiology: Aqueous penicillin G, 600,000 U, then IM procaine penicillin at 600,000 Uq8-12hrs
• Staphylococcal infection or no clues to etiology: penicil-linase-resistant penicillin (e.g., oxacillin 0.5-1.0 g poq6 hrs)
• Severe infection: penicillinase-resistant penicillin (e.g. nafcillin 1.0-1.5 g IV q4 hrs)
• Gram negative bacillus as possible etiology: aminogly-coside (gentamicin) plus a semisynthetic penicillin
• Rapidly progressive cellulitis after a fresh water injury: penicillinase-resistant penicillin plus gentamicin or chloramphenicol
• Human bites: amoxicillin-clavulanate (Augmentin)
• Animal bites (cellulitis at the saphenous site): penicillin or nafcillin, in high dosage, IV for 7 days before switching to oral therapy
• Facial cellulitis in adults and children: (H. influenza B) cefotaxime IV
• Gas forming cellulitis: Aqueous penicillin G 10-20 million U/day IV
• Diabetes mellitus: Cefoxitin or if toxic, clindamycin and gentamicin
• Intravenous drug abuse: Vancomydn and gentamicin
• Compromised hosts: clindamycin and gentamicin
• Burn patients: vancomycin and gentamicin

Contraindications: Allergies to the antibiotic

Precautions: Renal failure, other organ failure

Significant possible interactions: Refer to manufacturer’s literature

Alternative Drugs

Mild infection

• Penicillin allergy: erythromycin, 500 mg po q6 hrs

Severe infection

• Vancomycin 1.0-1.5 g/day IV
• Human bite and animal bites: IV cefoxitin

Gas forming cellulitis

• Metronidazole 500 mg IV q6h
• Clindamycin 600 mg IV q8h

Fluoroquinolones (adults)

Patient Monitoring

• A blood culture at the end of treatment to ensure cure
• Repeat needle aspirate culture
• Repeat blood count if patient was toxic
• Repeat lumbar puncture in case of meningitis

Prevention / Avoidance

• Treatment of tinea pedis with antifungal (such as clotrimazole) will prevent recurrent cellulitis of the legs in patients who have had coronary bypass
• Avoid trauma
• Avoid swimming in fresh water or salt water in the presence of skin abrasion
• Avoid human or animal bite
• Support stocking with peripheral edema
• Good skin hygiene
• For recurrent cellulitis — prophylactic penicillin G (250-500 mg po bid)
• H. influenzae cellulitis — rifampin prophylaxis for entire family of index case or in day-care classroom in which one or two children exposed. Dosage: 20 mg/kg/day (maximum: 600 mg/day) for 4 days.

Possible Complications

• Bacteremia
• Local abscesses
• Super infection with gram negative organisms
• Lymphangitis especially in recurrent cellulitis
• Thrombophlebitis of lower extremities in older patients
• Dissecting cellulitis of the scalp — scarring; alopecia
• Facial cellulitis in children — meningitis in 8% of patients
• Gas forming cellulitis — gangrene; amputation; 25% mortality

Expected Course / Prognosis

With adequate antibiotic treatment, outlook is good

Miscellaneous

Associated Conditions

Facial cellulitis in children

• Upper respiratory tract infection
• Unilateral or bilateral otitis media in 68% of patients
• Meningitis in 8% of patients

Perianal cellulitis

• Pharyngitis may precede the infection

Frontal sinus in adult OSubacute bacterial endocarditis

• Scarlet fever
• Vaccinia
• Herpes simplex
• Herpes zoster

Age-Related Factors

Pediatric: N/A

Geriatric: In cellulitis of lower extremities, patients are more prone to develop thrombophlebitis

Pregnancy

N/A

International Classification of Diseases

682.9 Cellulitis and abscess at unspecified site

See Also

Cellulitis, periorbital & orbital Erysipelas Animal bites Thrombophlebitis, superficial