Detection Of Mycolactone By Fluorescent Thin Layer Chromatography (F-Tlc) For The Diagnosis Of Buruli Ulcer

Abstract Buruli ulcer (BU) is a bacterial infectious disease of the subcutaneous fat caused by Mycobacterium ulcerans, resulting in chronic, devastating, necrotizing consequences. M. ulcerans produces a polyketide-derived macrolide toxin called mycolactone, required for the organism’s virulence. The disease manifests initially as a painless pre-ulcerative subcutaneous nodule, a plaque or as a rapidly progressing oedema. The oedema, the severe form breaks down to form characteristic ulcers with undermined edges which can progress to large necrotic lesions that, if untreated can extend to 15% of patient’s skin surface. With the recent introduction of antibiotic therapy by WHO, more emphasis has been placed on early diagnosis of BU. All forms of Buruli ulcer (papules, nodules, plagues, oedema and ulcers) however extensive, respond well to antibiotic treatment. However, antibiotics can only be administered upon adequate diagnosis of the disease, therefore, the earlier the diagnosis, the better. Acid-fast smear microscopy, culture, polymerase chain reaction (PCR), and histopathology are employed for the confirmation of BU. However, numerous challenges are encountered ranging from dedicated facilities and specialized equipment (culture or PCR), limited sensitivity (smear microscopy), to very demanding and time-consuming nature of both histopathology and culture of M. ulcerans in which results are available only after 6 – 12 weeks. The quest for a cheap and less time-consuming technique with the potential of being developed into a point-of-care diagnosis technique led to the discovery of the fluorescent-Thin Layer Chromatography (f-TLC) method. In this study, the f-TLC method was employed to detect the biomarker (mycolactone A/B) reported to be biosynthetically restricted to M. ulcerans and homogeneously distributed within infected tissue. Clinical evaluation of the diagnostic potential of the f-TLC technique in comparison to the gold standard PCR method in 50 suspected BU patients admitted into various health facilities: Agogo, Tepa, Dunkwa, Amasaman and Obom was iv undertaken. Among the suspected cases (n = 50), the sensitivity of f-TLC test was 77% and the specificity was 63%. The positive predictive value (PPV) and the negative predictive value (NPV) of the test were 69% and 71% respectively at their respective 95% CI. Preliminary exploration of the possibility of using urine from BALB/c mice infected with M. ulcerans disease showed that the mycolactone could be detected by the f-TLC method. Urine sampling therefore could potentially be a non-invasive, more convenient and co-operative sampling technique for patients suspected of BU.