Oedematous lesions are a less common but more severe form of Mycobacterium ulcerans disease. Misdiagnosis as bacterial cellulitis can lead to delays in treatment. We report the first comprehensive descriptions of the clinical features and risk factors of patients with oedematous disease from the Bellarine Peninsula of south-eastern Victoria, Australia.
Data on all confirmed Mycobacterium ulcerans cases managed at Barwon Health, Victoria, were collected from 1/1/1998–31/12/2012. A multivariate logistic regression model was used to assess associations with oedematous forms of Mycobacterium ulcerans disease.
Seventeen of 238 (7%) patients had oedematous Mycobacterium ulcerans lesions. Their median age was 70 years (IQR 17–82 years) and 71% were male. Twenty-one percent of lesions were WHO category one, 35% category two and 41% category three. 16 (94%) patients were initially diagnosed with cellulitis and received a median 14 days (IQR 9–17 days) of antibiotics and 65% required hospitalization prior to Mycobacterium ulcerans diagnosis. Fever was present in 50% and pain in 87% of patients. The WCC, neutrophil count and CRP were elevated in 54%, 62% and 75% of cases respectively. The median duration of antibiotic treatment was 84 days (IQR 67–96) and 94% of cases required surgical intervention. On multivariable analysis, there was an increased likelihood of a lesion being oedematous if on the hand (OR 85.62, 95% CI 13.69–535.70; P<0.001), elbow (OR 7.83, 95% CI 1.39–43.96; p<0.001) or ankle (OR 7.92, 95% CI 1.28–49.16; p<0.001), or if the patient had diabetes mellitus (OR 9.42, 95% CI 1.62–54.74; p = 0.02).
In an Australian population, oedematous Mycobacterium ulcerans lesions present with similar symptoms, signs and investigation results to, and are commonly mistakenly diagnosed for, bacterial limb cellulitis. There is an increased likelihood of oedematous lesions affecting the hand, elbow or ankle, and in patients with diabetes.
The oedematous form of Buruli ulcer, caused by Mycobacterium ulcerans, is less common representing 7% of cases over a 15 year period in a patient cohort from the Bellarine Peninsula of south-eastern Victoria, Australia. In this study, for oedematous Buruli ulcer cases, fever and pain were usually present and investigations showed leucocytosis, neutrophilia and a raised serum CRP. This is in contrast to other forms of Buruli ulcer which are classically painless and not associated with systemic symptoms. As a result oedematous cases were usually misdiagnosed and treated as bacterial cellulitis leading to delays in diagnosis, progression of disease, increased morbidity and increased complexity of treatment. Compared with non-oedematous forms of Buruli ulcer, we found that oedematous lesions were strongly associated with being located on the dorsum of the hand, the elbow and the ankle, and with patients who had diabetes mellitus. This study aims to increase the awareness of odematous Buruli ulcer disease, and improve the understanding of its clinical presentation and risk factors, to aid clinicians to diagnose and treat early Mycobacterium ulcerans infection when managing patients with cellulitis who have been exposed to areas endemic for Buruli ulcer.