DermNet provides Google Translate, a free machine translation service. Note that this may not provide an exact translation in all languages
Author: Dr Jenny Caesar, Dermatology Registrar, Glamorgan House, University Hospital of Wales, Cardiff, Wales, UK. DermNet NZ Editor in Chief: Adjunct A/Prof. Amanda Oakley, Dermatologist, Hamilton, New Zealand. Copy edited by Gus Mitchell. June 2020.
Diphtheria is a bacterial infection caused by Corynebacterium diphtheriae, a gram-positive bacillus. It generally affects the respiratory system and can also affect the skin. It can be prevented by vaccination and is very rare in countries with an immunisation programme.
Cutaneous diphtheria presents as a slow-healing ulcer.
Cutaneous diphtheria typically occurs in tropical areas where C. diphtheria is endemic, including in:
In developed countries, cutaneous diphtheria most commonly presents after travel to an endemic area in a pre-existing skin condition or wound. It usually affects unvaccinated individuals.
Outbreaks of cutaneous diphtheria have also been reported in disadvantaged communities living in overcrowded conditions with poor access to sanitary facilities and healthcare.
Transmission of cutaneous diphtheria is thought to occur via direct person-to-person contact with the infected skin and contaminated dressings.
Cutaneous diphtheria has also been reported after traditional tattooing .
Cutaneous diphtheria is caused by bacterial infection with Corynebacterium diphtheriae and less commonly, Corynebacterium ulcerans.
C. diphtheriae is a gram positive, non-encapsulated bacillus . Both toxigenic and non-toxigenic strains have been implicated in cutaneous infection.
Toxigenic strains of C. diphtheriae cause systemic toxicity.
Respiratory disease due to diphtheria characteristically presents as a thick, grey coloured membrane within the pharynx. Diphtheria can cause a sore throat, cervical lymphadenopathy, and progressive respiratory distress. Concurrent respiratory and skin infection are rare.
Cutaneous diphtheria is classically described as a well-circumscribed, non-healing ulcer with a ‘punched out’ appearance and covered by a grey membrane .
Lesions may start as a collection of vesicles which rapidly coalesce to form a clearly defined ulcer. They can be itchy, painful, and leak blood-stained exudate .
Localised injury to the skin often precedes infection, for example, a graze or insect bite . Cutaneous diphtheria has also been identified after colonisation and infection of an existing skin condition [3,4].
Cutaneous diphtheria can be non-specific, and may be challenging to distinguish from skin infection caused by another pathogen [1,4].
Unlike respiratory diphtheria, in which there is a slow immune response that may not lead to subsequent immunity, cutaneous diphtheria typically results in a rapid antibody response. This means that individuals with skin infection are unlikely to develop concurrent pharyngeal diphtheria.
Systemic toxicity from cutaneous diphtheria due to toxigenic strains of the bacteria is rare, only occurring in 1–2% of cases.
Possible systemic complications linked to toxigenic diphtheria include:
Infected skin can be a reservoir for passing the infection onto others, particularly in areas where herd immunity is low due to suboptimal immunisation.
The diagnosis of cutaneous diphtheria should be considered in a non-immunised individual with a non-healing ulcer and recent travel to an endemic area.
C. diphtheriae may be cultured from a bacterial wound swab.
As laboratory processing for diphtheria may not be routine, it is vital that complete clinical information is provided to alert the laboratory to consider culture for atypical organisms .
The differential diagnosis for cutaneous diphtheria includes:
Cutaneous diphtheria infection needs to be identified and treated to prevent spread of disease . Treatment includes:
Cases are no longer thought to be contagious after 48 hours treatment with antibiotics.
Diphtheria is a notifiable disease in New Zealand and public health advice should be sought. Contact tracing is advised for all close contacts. Nasal, pharyngeal, and skin swabs should be obtained from any wound sites. Contacts may require prophylaxis with erythromycin 500 mg QDS for 7–10 days.
Vaccination is essential to promote herd immunity and to reduce the risk of transmission of diphtheria. In New Zealand, vaccination against diphtheria is part of the National Immunisation Schedule and is given concurrently with tetanus and pertussis and sometimes also with polio, hepatitis B, and Haemophilus influenzae type b.
The prognosis for uncomplicated cutaneous diphtheria is good, with most cases responding to oral antibiotics and simple wound care measures.
Mortality is reported at 5–10% in systemic toxigenic diphtheria .
To prevent re-infection, individuals and close contacts should ensure their vaccination status is up to date.
© 2020 DermNet New Zealand Trust.
DermNet NZ does not provide an online consultation service. If you have any concerns with your skin or its treatment, see a dermatologist for advice.