Epidemiology, clinical features and diagnosis of Mycobacterium ulcerans in an Australian population.

Objective: To describe the epidemiology, clinical features and diagnosis of Mycobacterium ulcerans infection occurring on the Bellarine Peninsula in Victoria.

Design, Setting And Patients: Analysis of prospectively collected data on all patients with confirmed M. ulcerans infection reported from the Bellarine Peninsula and managed at Barwon Health between 1 January 1998 and 2 September 2011.

Main Outcome Measures: Proportion of cases by age group and sex; duration of symptoms; number, type and site of lesions; proportions diagnosed by polymerase chain reaction (PCR) testing and mycobacterial cultures.

Results: We identified 180 sequential cases of M. ulcerans infection: 42 cases in 1998-2004 and 138 in 2005-2011. Median patient age was 61 years (range, 1-94 years), and 49% of patients were male. Duration of symptoms before diagnosis varied from 2 to 270 days (median, 42 days). At presentation, 95% of patients had single lesions. Lower limbs were the most common site of lesions (61%), followed by upper limbs (34%); 40% occurred over a joint. Most lesions presented as ulcers (87%). Compared with the rest of the study population, patients aged > 60 years were more likely to have multiple lesions (odds ratio [OR], 8.1; 95% CI, 1.0-176.2; P = 0.04), and patients aged < 15 years were less likely to have lesions over a joint (OR, 0.2; 95% CI, 0.0-1.0; P = 0.02). Upper limb lesions were more common (OR, 2.2; 95% CI, 1.1-4.3; P = 0.02) and lower limb lesions less common (OR, 0.5; 95% CI, 0.5-0.9; P = 0.01) in male than female patients. Lesion swabs were PCR-positive in 99% of those tested, and positive on mycobacterial culture in 19%. Lesion biopsy samples were PCR-positive in 95% and mycobacterial culture-positive in 47%.

Conclusions: M. ulcerans infections are increasing in the Bellarine Peninsula. They usually present as single ulcerative lesions on limbs, commonly over joints. Age and sex influence clinical presentation, and PCR of lesions has high diagnostic sensitivity.