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Everything you need to know about ... impetigo

Sandra Lawton
RN OND
RN Dip(Child)
ENB393 MSc
Nurse Consultant
Dermatology Queen's Medical Centre
Nottingham

Impetigo, or impetigo contagiosa, is a contagious superficial bacterial skin infection frequently seen in children. It is the third most common skin disease affecting children after eczema and viral warts, with a peak incidence at 2-6 years.(2) Impetigo is usually classified as either primary impetigo, when bacteria directly invade minor breaks in normal skin, and secondary impetigo, where the infection is secondary to an underlying skin disease, such as eczema or scabies, which disrupts the skin barrier,(3) or as a result of trauma to the skin from burns, bites or lacerations.(4) There are two forms of impetigo: nonbullous impetigo, which accounts for three-quarters of cases, and bullous impetigo, although clinically both forms can be present (see Figures 1 and 2).(5)

[[NIP22_fig1_25]]

[[NIP22_fig2_25]]

Clinical presentations
Nonbullous impetigo is the most common form of impetigo. The lesions present as thin-walled vesicles (small fluid-filled blisters) that rupture very quickly  leaving superficial erosions covered with yellowish-brown or honey-coloured crusts. These crusts eventually dry, separate and disappear to leave red marks, which heal with no evidence of scarring.(3) Generally there are no systemic signs of fever, malaise or loss of appetite, and common sites of infection include the face and limbs, with satellite lesions occurring as a result of autoinoculation.(2)
Bullous impetigo is characterised by large, flaccid, fluid-filled bullae (blisters) that rupture less easily and persist for several days. The lesions are often multiple, painful, spread rapidly and can produce systemic symptoms.(2)
 
Causes
Impetigo is caused by Staphylococcus aureus or Streptococcus pyogenes bacteria. The main bacteria thought to cause nonbullous impetigo are Staph aureus, however, Strep pyogenes are sometimes isolated. Bullous impetigo is always caused by Staph aureus.(3)
 
History and diagnosis
Most cases of impetigo are straightforward to diagnose; diagnoses are usually made without swab results unless the condition is spreading to other family members, is persistent and has not responded to treatment.(5)
The history should include any pre-existing skin disease, trauma and general integrity of the skin before onset. The onset, location and appearance of the lesions, how long they have been present, and whether they are itchy or have spread should also be established. Are there any symptoms of systemic illness?
Family history should include the exposure to other family members with symptoms or with impetigo. Daily hygiene routines and the sharing of bedding and towels should be established. Has the impetigo been treated, and if so, what with and for how long?(6) This includes prescribed and over-the-counter preparations.

Additional diagnostics
If the condition is prolonged, fails to respond to treatment, or has spread to other family members, additional diagnostics may be required. It is important to swab the skin for bacteriological confirmation and antibiotic sensitivities. If there is further diagnostic doubt (see Table 1) or systemic symptoms, additional investigations may be required. If, for example, herpes simplex is suspected, a viral culture is required.(5,6)

[[NIP22_table1_26]]

Complications and prognosis
Impetigo commonly spreads to other areas of the body if not treated. The condition is contagious and can be passed to other family members or close contacts of the infected individual. Complications of nonbullous impetigo are rare; however, cellulitis, suppurative lymphadenitis, furunculosis, abscess formation or septicaemia can occur as a result of local and systemic spread, especially with immunosuppression.(3,1)    
Exotoxins produced by some strains of Staph aureus may occasionally result in staphylococcal toxic shock syndrome or scalded skin syndrome.(1) Noninfectious complications of Strep pyogenes infection can lead to guttate psoriasis, scarlet fever and glomerulonephritis (a form of inflammation of the kidney), although the incidence of acute glomerulonephritis has declined over the last few decades.(3)

Management
Information on the natural course of impetigo is lacking, and active treatment is usually given. In some cases impetigo may be self-limiting.(3,1) It is commonly recommended that crusting skin lesions be softened and removed by soaking in warm soapy water.(1,7) A recent systematic review found little evidence to support further disinfecting measures.(3) This review also found good evidence that topical mupirocin and topical fusidic acid are equally or more effective than oral treatment for people with limited disease. However, it was unclear whether oral antibiotics are superior to topical antibiotics for people with extensive impetigo.(3)
 
Treatment options
So in reality how does this relate to clinical practice? Resistance patterns against antibiotics change and should be taken into account in the choice of therapy. The appropriate use of antibiotics is vital for two main reasons:(3,8)

  • To ensure the best clinical outcome for the patient.
  • To reduce the development of further antibiotic resistance.

In the community, small, localised areas of acute impetigo may be treated by short-term topical application of fusidic acid; mupirocin should be used only in the presence of methicillin-resistant Staph aureus (MRSA). If the impetigo is extensive or longstanding, an oral antibacterial such as flucloxacillin (or erythromycin in penicillin allergy) should be used (see Box 1).(9)

[[NIP22_box1_28]]

Implications for nurse prescribing
Impetigo is one of the medical conditions listed in the nurse prescribers' extended formulary, which provides guidance on the use of oral antibacterials for the treatment of impetigo. As an independent nurse prescriber, it is important to recognise that the management of impetigo is multifaceted. It is important that the practitioner has an up-to-date clinical and pharmaceutical knowledge, is aware of their limitations, and is also aware of local and national policies in place.

Parent education
Care should be taken to avoid contagious spread of impetigo. It is generally suggested that advice to families should recommend:(1,7)

  • Careful handwashing after touching a patch of impetigo, and after applying antibiotic cream.
  • Avoiding sharing towels, flannels, bedding and so on, until the infection has gone.
  • That the patient's towels, pillowcases, and sheets should be changed after the first day of treatment, and clothing should be changed and laundered daily for the first few days.
  • That children should stay away from nursery or school for a few days after treatment has started, at least until new blisters and crusting stop appearing - although some say until the impetigo is clear.
  • Also, many parents are often anxious that the impetigo may reoccur. If this becomes a problem, bacterial swabs should be taken from the nose, skin and axilla.
  • Reassurance that this is a common problem, as many parents/patients feel dirty and disgusted by the thought.

Conclusion
Although impetigo is a superficial skin infection, it can be easily and effectively treated. By utilising the recent systematic review, practitioners are able to make informed decisions in relation to patient care. In summary, the review states that:(3)

  • There is no evidence for the value of disinfecting measures in the treatment of impetigo, either as sole or supplementary treatment.
  • There is good evidence that the topical antibiotics mupirocin and fusidic acid are equal to or possibly more effective than oral treatment for people with limited disease.
  • Fusidic acid and mupirocin are probably equally effective; other topical antibiotics seem to be less effective.
  • There is insufficient evidence to say whether oral antibiotics are better than topicals for more serious and extensive forms of impetigo. From a practical standpoint, oral antibiotics might be an easier option for people with very extensive impetigo.
  • Penicillin is not as effective as most other antibiotics.
  • Resistance patterns against antibiotics change, and this should be taken into account in the choice of therapy.

References

  1. Prodigy. Prodigy guidance: impetigo. 2002. Available from URL: http://www. prodigy.nhs.uk/guidance.asp?gt=Impetigo
  2. Sladden MJ, Johnston GA. Common skin infections in children. BMJ 2004;329:95-9.
  3. Koning S, Verhagen AP, van Suijlekom-Smit LWA, Morris A, Butler CC, van der Wouden JC. Interventions for impetigo. Cochrane Database of Systematic Reviews 2003;2.
  4. Fitzpatrick TB, Johnson RA, Wolff K. Color atlas and synopsis of clinical dermatology. New York: McGraw-Hill; 2001.
  5. Blenkinsopp A, Paxton P, Blenkinsopp J. Impetigo. Primary Health Care 2004;14(5):33-4.
  6. Burr S. Impetigo. In: Barnes K, editor. Paediatrics: a clinical guide for nurse practitioners. London: Butterworth Heinemann; 2003.
  7. British Association of Dermatologists. Impetigo patient information leaflet. London: BAD; 2004. 
  8. National Prescribing Centre. Antibiotic prescribing: a challenge for primary care. MeReC 2000;11(5):17-20. Available from URL: http://www.npc.co.uk/MeReC_Bulletins/2000Volumes/British
  9. British Medical Association and Royal Pharmaceutical Society of Great Britain. British National Formulary. No. 48. London: BMA and RPSGB; 2004.

Resources
British Association of Dermatologists
4 Fitzroy Square
London W1T 5HQ
T:020 7383 0266
F:020 73885263
W:www.bad.org.uk
Skin Conditions Specialist Library
W:http://libraries.nelh.nhs.uk/skin/
Department of Health Nurse Prescribing Information
W:http://www.dh.gov.uk/PolicyAndGuidance/MedicinesPharmacyAndIndustry/Pres...