Page content: Victorian statutory requirement | Infectious agent | Identification | Incubation period | Public health significance & occurrence | Reservoir | Mode of transmission | Period of communicability | Susceptibility & resistance | Control measures | Outbreak measures | Additional sources of information

Victorian statutory requirement

Notification is not required.

School exclusion: exclude until appropriate treatment has commenced. Sores on exposed surfaces must be covered with a watertight dressing.

Infectious agent

Various strains of Streptococcus pyogenes, group A streptococci (GAS) and Staphylococcus aureus cause disease.

Identification

Clinical features
Impetigo is a contagious superficial skin infection seen mainly in children but it may occur at any age. The infection may present with mildly irritating blisters that become pustular and erode rapidly leaving a honey-coloured crust. It often appears around the nose and mouth.

Local lymph nodes may be enlarged and the affected child may occasionally be acutely ill.

Impetigo due to S. pyogenes is not generally associated with scarlet fever but may rarely cause a glomerulonephritis. This usually occurs three to eight weeks after the skin infection. Skin GAS infections may be an important risk factor for rheumatic heart disease, independent of throat GAS carriage.

Impetigo in the neonate often follows S. aureus colonisation of the nose, umbilicus, rectum or conjunctivae. The lesions are initially vesicular and become seropustular and may develop bullae (bullous impetigo). Lesions are most common in the nappy area. Complications are rare.

Staphylococcal skin infections rarely result in the more severe ‘scalded skin syndrome’ which varies from a diffuse scarlatiniform erythema to a generalised bullous desquamation of the skin.

Method of diagnosis
Diagnosis should be confirmed by isolation of the organism from skin swabs. This also allows confirmation of antibiotic susceptibility.

Incubation period

The incubation period is one to three days for S. pyogenes and four to ten days for S. aureus.

Public health significance & occurrence

Occurrence is worldwide. Impetigo is a rapidly spreading, highly contagious skin infection that frequently occurs in children’s settings such as day care centres, kindergartens and schools.

Reservoir

Humans.

Mode of transmission

The organisms enter through damaged skin and are transmitted through direct contact with patients or asymptomatic carriers. Nasal carriers are particularly likely to transmit disease. It is rarely transmitted by indirect contact with objects.

Period of communicability

If untreated, purulent discharges may remain infectious for weeks to months.
Most cases are no longer infectious after 24 hours of appropriate antibiotic therapy.

Susceptibility & resistance

Everyone is susceptible to streptococcal and staphylococcal skin infection.

Persons suffering from chronic conditions producing breaks in the skin, such as eczema or atopic dermatitis, may be at greater risk of impetigo.

Control measures

Preventive measures
Good personal hygiene practices including a daily bath or shower. Emphasise the importance of not sharing toilet articles and of suitably covering cuts and abrasions.

Educate on modes of transmission and possible complications of impetigo and reinforce the importance of treating cases promptly.

Control of case
General therapy may consist of saline or soap and water or aluminium acetate solution or potassium permanganate solution to remove crusts.

For cases where Streptococcus pyogenes is suspected or confirmed treatment is generally phenoxymethylpenicillin or benzathine penicillin.

Patients with penicillin hypersensitivity are generally given roxithromycin.

For cases where Staphylococcal aureus is suspected or confirmed mupirocin ointment is the usual treatment.

For severe, widespread or longstanding infections flucloxacillin, cephalexin or roxithromycin may be used as each of these drugs is active against both S. aureus and S. pyogenes.

In all cases see the current edition of the Therapeutic guidelines: antibiotic (Therapeutic Guidelines Limited).

General advice for patients with impetigo includes:

• consider using anti-bacterial soap for bathing for two to three weeks
• dispose of soiled dressings appropriately
• emphasise the need for hand washing, especially after changing dressings, and the importance of avoiding sharing toilet articles, towels, clothing or bed linen
• avoid scratching or touching the lesions to prevent spread to other areas of the body
• advise on the importance of completing the recommended antibiotic course.

Patients must be excluded from school or child care services until antibiotic treatment has commenced. Sores on exposed surfaces such as scalp, face, hands or legs must be covered with a watertight dressing.

Control of contacts
Advice to household members should include:

• education about the mode of transmission
• avoiding direct contact with lesions on the affected person if possible
• remembering to wash hands regularly particularly after touching the lesions or scabs of the infected person and use gloves where possible
• refer symptomatic contacts for appropriate treatment.

Control of environment
See Control of contacts, above.

Outbreak measures

Child care settings and schools

• Exclude all confirmed cases and refer suspected cases for appropriate treatment and management.
• Emphasise the need for good hand washing procedures for all staff and children.
• Advise parents of other children and staff who may have had contact with the cases to remain vigilant for signs of impetigo and seek treatment if symptoms develop.
• Ensure that sores on exposed skin surfaces of confirmed cases are covered with a watertight dressing while at school.

Hospital nursery or maternity ward

• Cohort cases and contacts until all have been discharged. Staff working with colonised infants should not work with non-colonised newborns.
• Obtain swabs from discharging lesions to determine organism.

Treat confirmed cases with appropriate antibiotics.

• Draining lesions should be covered at all times with a dressing.
• Trace and determine source of infection. Consider:
  • examining staff for active lesions anywhere on the body
  • obtaining nasal swabs from staff to detect asymptomatic carriers and treating accordingly.
• Promote the need for good hand washing and hygiene practices among staff and visitors to the unit where the outbreak has occurred.
• Investigate adequacy of infection control procedures and the availability of hand washing facilities including antiseptic hand solutions.

Additional sources of information

• Centers for Disease Control and Prevention, Group A Streptococcal (GAS) Disease
• Shelby-James, TM, Leach, AJ, Carapetis, JR, Currie, BJ, Mathews, JD 2002, ‘Impact of single dose azithromycin on group A streptococci in the upper respiratory tract and skin of Aboriginal children’, Pediatr Infect Dis J, vol. 21, no. 5, pp. 375–80.