Mycobacterium ulcerans DNA not detected in faecal samples from Buruli ulcer patients: results of a pilot study

Abstract

It has recently been shown that in a Buruli ulcer (BU) endemic region of southeastern Australia, significant numbers of possums (native tree-dwelling marsupials) have clinical BU disease. Furthermore, based on quantitative PCR (qPCR) analysis, animals with BU lesions (and some without) shed M. ulcerans DNA in their faeces, indicative of bacterial loads of up to 10(8) organisms/gram. These findings led us to propose that humans might also harbour M. ulcerans in their gastrointestinal tract and shed the bacterium in their faeces. We conducted a pilot study and collected faecal swabs from 26 patients with confirmed BU and 31 healthy household controls. Faecal samples were also collected from 10 healthy controls from non-endemic regions in Ghana. All 67 specimens were negative when tested by IS2404 PCR. The detection sensitivity of this method was ≥10(4) bacteria per gram (wet-weight) of human faecal material. We conclude that the human gastrointestinal tract is unlikely to be a significant reservoir of M. ulcerans.

Figure 1. Results of spiking experiment, showing sensitivity of IS2404 qPCR for the detection of M. ulcerans in human faecal material.

Depicted is the mean and standard deviation of duplicate samples. IPC: Internal Positive Control.

Figure 2. Clinical presentation of three, confirmed BU patients enrolled in this study showing: (A) nodule of the right knee; (B) ulcer of the right elbow; (C) ulcer of the left hand at diagnosis; and (D) ulcer of the right elbow 6 weeks post diagnosis and commencement of SR8 with surgical intervention.