History

Fact Explanation
High fever Fever is due to the inflammatory mediators that are released during the multiplication and destruction of the bacteria[4] due to the immune reactions.These endogenous pyrogens act on the hypothalamus and alter the temperature set point.[2],[3],[6]
Swelling of the affected region This may affect the limbs,the peri orbital area in peri orbital cellulitis or the abdomen.This is due to exudation of tissue fluid due to increased permeability of capillary walls and lymphangitis. The increased vascular permeability occurs due to histamine release, direct endothelial injury and leukocyte-mediated endothelial injury. [1]
Pain and tenderness Cytokines, chemokines, nerve growth factor, and prostaglandins released by leukocytes and local cells stimulate the nerve endings and produce pain. [2],[6]
Erythema of the affected area Occurs due to vasodilation, which opens up the arterioles and new capillary beds. The increased blood flow causes warmth and erythema. [1],[6]
Limitation of movement Occurs due to pain and edema of the affected area.
Vesicles and/or bullae Accumulation of pus beneath superficial layers of the skin. [3],[4]
History of trauma, cutaneous ulcers causing breach of skin Allows for the entry of pathogen to enter the tissues and multiply rapidly because the host defense is limited by factors such as local circulation,venous stagnation.[3],[6]
Predisposing factors Factors that reduce venous or lymph drainage such as lymph-edema[4],[5], chronic venous congestion[6] are risk factors for the development of cellulitis. Factors that cause host immune suppression such as diabetes mellitus, Cushing's syndrome etc. also predispose to cellulitis. [3],[6]
References
  1. KUMAR Vinay, ABBAS Abul K, ASTER Jon.ed. Robbins Basic Pathology. 9th edition. Philadelphia. Saunders Elsevier. 2012.
  2. BARRETT Kim E, BOITANO, Scott, BARMAN Susan M, BROOKS Heddwen L ed. Ganong’s Review of Medical Physiology. 23rd edition. New York. McGraw Hill. 2010.
  3. Practice Guidelines for the Diagnosis and Management of Skin and Soft-Tissue Infections. Infectious Diseases Society of America. 2005. Available from: http://www.uphs.upenn.edu/bugdrug/antibiotic_manual/idsasst05.pdf
  4. Guidelines on Management of Cellulitis in Adults. Clinical Resource Efficiency Support Team (CREST) Guidelines. 2005. Available from: www.acutemed.co.uk/docs/Cellulitis%20guidelines,%20CREST,%2005.pdf
  5. Consensus document on the Management of Cellulitis in Lymphedema. Revised Cellulitis Guidelines. British Lymphology Society. 2013. Available from: http://www.lymphoedema.org/Menu3/Revised%20Cellulitis%20Consensus%202013.pdf
  6. Understanding cellulitis of lower limb. Wound Essentials Vol-2 2007. Available from: www.woundsinternational.com/pdf/content_183.pdf

Examination

Fact Explanation
Febrile Fever caused by the inflammatory mediators that are released during bacterial multiplication and destruction. These endogenous pyrogens act on the hypothalamus and alter the temperature set point[2],[6]
Tachycardia Acute infections stimulate the release of catecholamines that have a chronotropic effect on the heart.
Hypotension Low blood pressure defined as systolic<90mmHg or diastolic<60mmHg occurs only if sepsis results in generalized vasodilation subsequently causing septic shock.
Edema overlying the affected area This is due to exudation of tissue fluid due to increased permeability of capillary walls and lymphangitis. The increased vascular permeability occurs due to histamine release, direct endothelial injury and leukocyte-mediated endothelial injury.
Warmth and erythema Occurs due to vasodilation, which opens up the arterioles and new capillary beds. The increased blood flow causes warmth and erythema.[1],[6]
Localized lymphnodal enlargement Inflammatory reaction of the draining lymph nodes and increased lymphatic flow causes tender enlarged lymph nodes.[1],[6]
Breaches of the skin Signs of trauma, skin infections such as impetigo or ecthyma, chronic ulcers, fissured toe webs and inflammatory dermatoses such as eczema are predisposing factors.[3],[4]
Signs pointing toward possible predisposing factors Surgical scars or radiotherapy marks may unmask limb lymphedema. Signs of peripheral vascular disease or peripheral neuropathy may point towards possible diabetes mellitus. [3],[7]
References
  1. KUMAR Vinay, ABBAS Abul K, ASTER Jon.ed. Robbins Basic Pathology. 9th edition. Philadelphia. Saunders Elsevier. 2012.
  2. BARRETT Kim E, BOITANO, Scott, BARMAN Susan M, BROOKS Heddwen L ed. Ganong’s Review of Medical Physiology. 23rd edition. New York. McGraw Hill. 2010.
  3. Practice Guidelines for the Diagnosis and Management of Skin and Soft-Tissue Infections. Infectious Diseases Society of America. 2005. Available from: http://www.uphs.upenn.edu/bugdrug/antibiotic_manual/idsasst05.pdf
  4. Guidelines on Management of Cellulitis in Adults. Clinical Resource Efficiency Support Team (CREST) Guidelines. 2005. Available from: www.acutemed.co.uk/docs/Cellulitis%20guidelines,%20CREST,%2005.pdf
  5. Consensus document on the Management of Cellulitis in Lymphedema. Revised Cellulitis Guidelines. British Lymphology Society. 2013. Available from: http://www.lymphoedema.org/Menu3/Revised%20Cellulitis%20Consensus%202013.pdf
  6. Understanding cellulitis of lower limb. Wound Essentials Vol-2 2007. Available from: www.woundsinternational.com/pdf/content_183.pdf
  7. Lipsky BA, Berendt AR, Cornia PB, et al. 2012 Infectious Diseases Society of America clinical practice guideline for the diagnosis and treatment of diabetic foot infections. Clin Infect Dis. [Online] 2012;54(12):e132-73.[viewed 17 April 2014]. doi: 10.1056/NEJM199710303371801

Differential Diagnoses

Fact Explanation
Erysipelas Erysipelas affects the upper dermis, including the superficial lymphatics, whereas cellulitis involves the deeper dermis, as well as subcutaneous fat.[2] Clinically evident as a well demarcated erythematous area.
Necrotizing Fasciitis In the Initial stages presentation is similar to cellulitis. Infection spreads rapidly in the subcutaneous structures. Features supportive of a diagnosis of Necrotizing Fasciitis are: marked pain, erythema, severe edema, high fever, necrosed skin with bullae and crepitations. [1],[2]
Lipodermatosclerosis Patient has a history of varicose veins. Lipodermatosclerosis is seen commonly in middle-aged women with venous insufficiency. There is a predilection for the skin overlying the Gaiter's area (medial malleolus). Varicose eczema is often bilateral, with crusting, scaling and itchiness.[2]
Deep Vein Thrombosis (DVT) Commonest presenting complaints are edema,pain and erythema. Symptoms occur below the level of thrombus. There is severe pain on dorsiflexion (Homan’s sign). [3] Prolonged immobility, contraceptive pills, thrombogenic diseases such as antiphospholipid syndrome, a positive family history are significant risk factors.
Lyme disease The bacterium Borrelia burgdorferi is transmitted via the bite of infected blacklegged ticks. Symptoms include fever, constitutional symptoms and a characteristic skin rash: erythema migrans. If left untreated, infection can involve joints, heart and the nervous system[1]
Contact dermatitis Well-demarcated skin lesion, pruritus and exposure to allergenic substances are suggestive of this condition.[1],[2]
Insect bites History of insect bite accompanied by pain and pruritus.[1]
Eosinophilic Cellulitis (Wells syndrome) A period of itching and burning pain may precede onset of single or multiple lesions. This is recurrent and takes 2-3 weeks to resolve. [1]
Erythema nodosum Presents with a solitary tender erythematous plaque. Accompanied by fever and malaise with time progresses into more discrete subcutaneous nodules.[1]
References
  1. KROSHINSKY Daniela. GROSSMAN Marc E, FOX Lindy P. Approach to the Patient With Presumed Cellulitis. Seminars in Cutaneous Medicine and Surgery[online]. Elsevier Inc. 2007.[viewed 17 April 2014] Available from: http://cursa.ihmc.us/rid=1GM08JMTN-J48J0M-1FFT/Cellulitis.pdf
  2. Guidelines on Management of Cellulitis in Adults. Clinical Resource Efficiency Support Team (CREST) Guidelines. 2005. Available from: www.acutemed.co.uk/docs/Cellulitis%20guidelines,%20CREST,%2005.pdf
  3. Understanding cellulitis of lower limb. Wound Essentials Vol-2 2007. Available from: www.woundsinternational.com/pdf/content_183.pdf

Investigations - for Diagnosis

Fact Explanation
Full blood count with differential count Raised white cell with neutrophil leucocytosis is observed. The bone marrow is stimulated to produce and release increased numbers of neutrophils in response to bacterial pathogen invasion of the blood.[1],[2],[3]
C-reactive protein Is an acute phase protein that is elevated in bacterial infections. Useful in diagnosis and monitoring response to treatment. [1]
Culture and antibiogram of aspirate/ wound swab Aspirates are positive in 10% while punch biopsy is positive in 20%. [1],[2]
Blood culture Blood cultures are positive in 2-4% of cases, however contaminants may give false positives. This investigation is indicated if sepsis is suspected.[1],[2]
Anti Streptolysin O Titres (ASOT) Serological tests are not used regularly. This is useful if cellulitis has led to a subsequent acute glomerulonephritis.
Blood urea and serum electrolytes. Indicates renal compromise in shock and acute glomerulonephritis.
X-ray Indicated if underlying osteomyelitis is suspected. [3]
MRI If gas gangrene, necrotising fasciitis or an abscess is suspected an MRI may be useful. [3]
References
  1. Guidelines on Management of Cellulitis in Adults. Clinical Resource Efficiency Support Team (CREST) Guidelines. 2005. Available from: www.acutemed.co.uk/docs/Cellulitis%20guidelines,%20CREST,%2005.pdf
  2. Practice Guidelines for the Diagnosis and Management of Skin and Soft-Tissue Infections. Infectious Diseases Society of America. 2005. Available from: http://www.uphs.upenn.edu/bugdrug/antibiotic_manual/idsasst05.pdf
  3. Lipsky BA, Berendt AR, Cornia PB, et al. 2012 Infectious Diseases Society of America clinical practice guideline for the diagnosis and treatment of diabetic foot infections. Clin Infect Dis. [Online] 2012;54(12):e132-73.[viewed 17 April 2014]. doi: 10.1056/NEJM199710303371801

Investigations - Fitness for Management

Fact Explanation
Assessment of blood glucose levels Diabetes Mellitus is a recognized risk factor for cellulitis, therefore it is important to screen for diabetes. In addition acute inflammation will elevate plasma glucose levels.
Assessment for Peripheral Vascular Disease (PVD) Ankle Brachial Pressure Index (ABPI) testing should be performed. Additional investigations such as duplex ultrasonography, magnetic resonance arteriography, and angiography are used only if there is a strong suggestion of PVD.[4]
Assessment for varicose veins A venous duplex scan or a venogram is useful in the assessment of chronic varicose veins.
References
  1. Definition and diagnosis of Diabetes Mellitus and intermediate hyperglycemia -Report of a WHO/ IDF consultation. World Health Organization. 2006. [Viewed 17 April 2014] Available from:http://www.who.int/diabetes/publications/Definition%20and%20diagnosis%20of%20diabetes_new.pdf
  2. The management of Type 2 Diabetes. Clinical Guideline 66 .National Institute for Health and Clinical Excellence. 2009. [viewed 17 April 2014]. Available from: http://www.nice.org.uk/nicemedia/pdf/CG87NICEGuideline.pdf
  3. FOWLER MJ. Microvascular and Macrovascular Complications of Diabetes. Clinical Diabetes [ONLINE]. 2008;26(2):77-82.[viewed 17 April 2104] Available from: http://clinical.diabetesjournals.org/content/26/2/77.long
  4. SONTHEIMER Daniel L. Peripheral Vascular Disease: Diagnosis and Treatment. Am Fam Physician. [online] 2006 Jun 1;73(11):1971-1976. [viewed 4 April 2014] Available from: http://www.aafp.org/afp/2006/0601/p1971.html

Management - General Measures

Fact Explanation
Choice of management setting Signs of sepsis, deteriorating systemic signs or deteriorating local signs even with optimal outpatient treatment are indications for hospitalization, unless close follow up can provided by a primary care physician. [3]
Analgesia This makes the patient comfortable and improves recovery. Commonly used analgesics are paracetamol, NSAIDs and oral opioids. [1],[3]
Anti-pyretics Use of antipyretics improves the general patient condition. [1],
Ensure adequate hydration Febrile patients are likely to become dehydrated. This can be aggravated due to inadequate fluid intake. Dehydration reduces organ perfusion and may lead to acute kidney injury.[1]
Elevation of the affected limb Improves lymphatic and venous return.[1],[3],[4]
Aseptic aspiration/ deroofing of blisters Blisters contains fluid that is a good culture medium. Therefore removal of blisters is advisable. [1]
Compression bandaging Once the acute stage has subsided the patient should be assessed for applying compression bandages to reduce limb edema. [1],[3]
References
  1. Guidelines on Management of Cellulitis in Adults. Clinical Resource Efficiency Support Team (CREST) Guidelines. 2005. Available from: www.acutemed.co.uk/docs/Cellulitis%20guidelines,%20CREST,%2005.pdf
  2. Understanding cellulitis of lower limb. Wound Essentials Vol-2 2007. Available from: www.woundsinternational.com/pdf/content_183.pdf
  3. Consensus document on the Management of Cellulitis in Lymphedema. Revised Cellulitis Guidelines. British Lymphology Society. 2013. Available from: http://www.lymphoedema.org/Menu3/Revised%20Cellulitis%20Consensus%202013.pdf
  4. Practice Guidelines for the Diagnosis and Management of Skin and Soft-Tissue Infections. Infectious Diseases Society of America. 2005. Available from: http://www.uphs.upenn.edu/bugdrug/antibiotic_manual/idsasst05.pdf

Management - Specific Treatments

Fact Explanation
Flucloxacillin Cellulitis is commonly caused by beta-haemolytic streptococci or S.aureus. Flucloxacillin is a bactericidal to both types. It can be combined with benzylpenicillin while Ceftriaxone an alternative drug. [1],[2],[3]
Clarythromycin/Clindamycin (iv) Used in patients with a penicillin allergy.[2] Clindamycin inhibits toxin production by group A streptococci, C. prefringens and S. aureus. [1]
Benzylpenicillin (IV)+ciprofloxacin+clindamycin(IV) This regime is used in patients with class IV(With shock) cellulitis.[1]
Co-amoxiclav, Doxycycline and Metronidazole In atypical cellulitis due to human/animal bite.These antibiotics provide cover against Gram negative organisms. [1]
Surgical management Indicated only in chronic ulcers, underlying abscesses or necrotising fasciitis.[5]
Propyhlaxis for recurrent cellulitis For patients who have had 2 or more episodes of cellulitis at the same site should receive prophylaxis with: Penicillin 250mg bd or Erythromycin 250mg bd for up to 2 years. [1],[3]
References
  1. Guidelines on Management of Cellulitis in Adults. Clinical Resource Efficiency Support Team (CREST) Guidelines. 2005. Available from: www.acutemed.co.uk/docs/Cellulitis%20guidelines,%20CREST,%2005.pdf
  2. Practice Guidelines for the Diagnosis and Management of Skin and Soft-Tissue Infections. Infectious Diseases Society of America. 2005. Available from: http://www.uphs.upenn.edu/bugdrug/antibiotic_manual/idsasst05.pdf
  3. Understanding cellulitis of lower limb. Wound Essentials Vol-2 2007. Available from: www.woundsinternational.com/pdf/content_183.pdf
  4. Consensus document on the Management of Cellulitis in Lymphedema. Revised Cellulitis Guidelines. British Lymphology Society. 2013. Available from: http://www.lymphoedema.org/Menu3/Revised%20Cellulitis%20Consensus%202013.pdf
  5. Lipsky BA, Berendt AR, Cornia PB, et al. 2012 Infectious Diseases Society of America clinical practice guideline for the diagnosis and treatment of diabetic foot infections. Clin Infect Dis. [Online] 2012;54(12):e132-73.[viewed 17 April 2014]. doi: 10.1056/NEJM199710303371801