History

Fact Explanation
Thin walled, easily ruptured vesicles with a distribution on face, neck with yellow colored exudate. Pathognomonic feature in the non bullous form caued by infection with Group A beta hemolytic Streptococci or Staphylococci.[1][2]
Blisters of 1-2cm in diameter on face and extremities This presentation is associated with the bullous form of impetigo caused by Infection with Staphylococcus aureus. [1][2]
Recent history of eczema, scabies, chickenpox or abrasions Impetigo can be a result of secondary infection of traumatized and open lesions by auto inoculation of bacteria. [1][2]
Pruritus [1] Is an occasional complaint and is often nocturnal.
Lesions are painless and non-erythematous The superficial skin has poor blood supply and it is pain insensitive.[2]
Neonatal bullous impetigo Bullae are seen in the diaper area. Rupture of bullae occurs easily, leaving a narrow rim of scales at the edge of a shallow, moist erosion[2]
Post streptococcal glomerulonephritis Occurs as a complication of streptococcal skin infection. The following symptoms and signs are the commonest: oliguria, hematuria, elevated blood pressure, features of acute renal failure such as oliguria, nausea, vomiting, abdominal pain ,drowsiness. This is due to an immunological cross reaction against antigens of nephritogenic strains of Group A Beta-Haemolytic Streptococci. [3]
References
  1. GAWKRODGER, David J, ARDERN-JONES Michael R. Dermatology-An Illustrated Color Text. 5th edition. New York. Churchill Livingstone Elsevier.2012.
  2. MORELLI Joseph G. Chapter 664: Cutaneous Bacterial Infections. In: KLIEGMAN Robert M, BEHRMAN Richard E, JENSON, Hal B, STANTON, Bonita F ed. Nelson Textbook of Pediatrics, 18th edition. Philadelphia. Saunders Elsevier. 2007.
  3. COLE Charles, GAZEWOOD John. Diagnosis and Treatment of Impetigo. Am Fam Physician. [Online] 2007 Mar 15;75(6):859-864. [Viewed 18 April 2014]. Available from: http://www.aafp.org/afp/2007/0315/p859.html

Examination

Fact Explanation
Thin walled, vesicles on face, neck with yellow colored exudate [1],[2] Pathognomonic feature in the non bullous form caued by infection with Group A beta hemolytic Streptococci or Staphylococci.[1][2]
Blisters of 1-2cm in diameter on face and extremities [1],[2] This presentation is associated with the bullous form of impetigo caused by Infection with Staphylococcus aureus. [1][2]
Regional lymph node enlargement Immune reaction following extension of the infection deeper in to the skin which has got better blood any lymph drainage[1][2]
High blood pressure Observed in post streptococcal glomerulonephritis that causes acute renal failure.
References
  1. GAWKRODGER, David J, ARDERN-JONES Michael R. Dermatology-An Illustrated Color Text. 5th edition. New York. Churchill Livingstone Elsevier.2012.
  2. MORELLI Joseph G. Chapter 664: Cutaneous Bacterial Infections. In: KLIEGMAN Robert M, BEHRMAN Richard E, JENSON, Hal B, STANTON, Bonita F ed. Nelson Textbook of Pediatrics, 18th edition. Philadelphia. Saunders Elsevier. 2007.

Differential Diagnoses

Fact Explanation
Varicella zoster Vesicles are similar to non bullous impetigo.This disease has a characteristic dermatomal distribution.[1]
Tinea corporis Similar to non bullous impetigo but tinea corporis is associated with severe itching and the lesions have an expanding scaly centers and a erythematous edge.[1]
Scabies Similar to non bullous impetigo but Scabies is associated with severe localized pruritus. The burrows are characteristic .The distribution is in the extremities. Infants commonly show facial involvement.[1]
Epidermolysis bullosa Resembles neonatal bullous impetigo. However blisters occur in the skin and mucosal membranes.Characteristically blisters also occur on internal organs, such as the esophagus. This occurs at birth or shortly after, which is different from the age of onset for neonatal impetigo.[1],[2]
Staphylococcal scalded skin syndrome A differential diagnosis for bullous impetigo in neonates but the onset is with fever and widespread erythema which rapidly progresses in to fluid-filled blisters.Child is often more toxic than in impetigo. [1],[2]
Allergic contact dermatitis Similar to non bullous impetigo in an older child. However, allergic dermatitis has a more sub acute onset. Hyper pigmented, lichenified nature of the lesions is a differentiating factor.[1],[2]
Bullous pemphigoid Similar to bullous impetigo, but cause tense, fluid-filled, itchy blisters with a smooth surface and annular margins. Upon healing the skin becomes brownish hyper pigmented. [1],[2]
Bullous erythema multiforme The vesicles or bullae arise from a portion of red plaques, can extend up to 1 to 5 cm in diameter, on the extensor surfaces of extremities. [2]
Bullous lupus erythematosus Causes a widespread vesiculobullous eruption that may be pruritic; tends to favor the upper part of the trunk and proximal upper extremities.[2]
References
  1. MORELLI Joseph G. Chapter 664: Cutaneous Bacterial Infections. In: KLIEGMAN Robert M, BEHRMAN Richard E, JENSON, Hal B, STANTON, Bonita F ed. Nelson Textbook of Pediatrics, 18th edition. Philadelphia. Saunders Elsevier. 2007.
  2. COLE Charles, GAZEWOOD John. Diagnosis and Treatment of Impetigo. Am Fam Physician. [Online] 2007 Mar 15;75(6):859-864. [Viewed 18 April 2014]. Available from: http://www.aafp.org/afp/2007/0315/p859.html

Investigations - for Diagnosis

Fact Explanation
Culture, antibiogram, gram stain of blister fluid [1] For identification of the pathogenic bacteria and to determine antibiotic sensitivity. If swab culture is negative, gram stain is useful in identifying pathogens. [1]
Blood culture and antibiogram [1] A positive blood culture should prompt vigorous treatment, that includes hospitalization and intravenous antibiotics.
Full blood count with differential leucocyte count. [1] A neutrophilic leukocytosis indicates complicated impetigo with possible cellulitis or sepsis.
C-reactive protein (CRP) An inflammatory market that becomes elevated in acute inflammation or bacterial infection. Useful in diagnosis and monitoring response to therapy in complicated impetigo.
Assessment of renal function: Blood urea nitrogen, serum creatinine, estimated glomerular filtration rate (eGFR) [2] To asess renal functions in suspected post- streptococcal glomerular nephritis.
Anti Streptolysin O Titers (ASOT) [2] A raised ASOT is indicative of a diagnosis of post- streptococcal glomerular nephritis.
References
  1. MORELLI Joseph G. Chapter 664: Cutaneous Bacterial Infections. In: KLIEGMAN Robert M, BEHRMAN Richard E, JENSON, Hal B, STANTON, Bonita F ed. Nelson Textbook of Pediatrics, 18th edition. Philadelphia. Saunders Elsevier. 2007.
  2. COLE Charles, GAZEWOOD John. Diagnosis and Treatment of Impetigo. Am Fam Physician. [Online] 2007 Mar 15;75(6):859-864. [Viewed 18 April 2014]. Available from: http://www.aafp.org/afp/2007/0315/p859.html

Management - General Measures

Fact Explanation
Antipyretics Paracetamol at a dose of 15mg/kg/day can be used. This is useful in managing complicated cases of impetigo where the child may develop fever. [1]
Education on hygienic practices Educate the patient and parents on hygienic practices that prevent further spread of the illness. The following can be recommended: hand washing with soap, regular washing of the child's clothes. [1]
Avoid school for one week after therapy Minimizes spread to other close contacts and prevent infection with other bacterial strains.[1]
Examine and treat close contacts Prevents reinfection with the same pathogen is common if the close contacts are also colonized with the pathogen. [1]
References
  1. PAIGE D.G. Skin Diseases. In: KUMAR Parveen, CLARK Michael ed. Kumar & Clark's Clinical Medicine. 8th edition. London. Saunders Elsevier. 2012.

Management - Specific Treatments

Fact Explanation
Mupirocin Topical application three times daily for 7–10 days. Is bactericidal and effective against MRSA.[1],[2],[3]
Erythromycin Preferred oral medication for a systemically ill patient who has developed cellulitis, abscesses, suppurative lymphadenitis or if there is a risk of topical medication being licked off by the child.[1],[3]
Fusidic acid Topical application 3–4 times a day, for 7 days. Effective against staphylococcal infections, an alternative to Mupirocin. [1]
Flucloxacillin An oral drug, that is bactericidal, effective against beta lactamase producing staphylococci and in erythromycin resistance. [1],[2]
Amoxicillin clavulanate An oral drug with bactericidal action, useful in beta lactamase producing staphylococci and erythromycin resistance.[1],[2]
Clarithromycin/ Azithromycin Useful if erythromycin is poorly tolerated. [1],[2]
Vancomycin Effective in impetigo caused by MRSA. [2],[3]
References
  1. MORELLI Joseph G. Chapter 664: Cutaneous Bacterial Infections. In: KLIEGMAN Robert M, BEHRMAN Richard E, JENSON, Hal B, STANTON, Bonita F ed. Nelson Textbook of Pediatrics, 18th edition. Philadelphia. Saunders Elsevier. 2007.
  2. MARTIN John et.al ed. BNF for Children. London. BMJ Group, Royal Pharmaceutical Society of Great Britain and RCPCH Publications Ltd. 2011.
  3. COLE Charles, GAZEWOOD John. Diagnosis and Treatment of Impetigo. Am Fam Physician. [Online] 2007 Mar 15;75(6):859-864. [Viewed 18 April 2014]. Available from: http://www.aafp.org/afp/2007/0315/p859.html