Clinical considerations on Buruli ulcer employing two molecular tests for the detection of Mycobacterium ulcerans in 100 skin biopsies. (10th December 2013)

• Record Type: Journal Article
• Authors: Leigheb, Giorgio; Zavattaro, Elisa; Molicotti, Paola; Cannas, Sara; Zanetti, Stephania; Clemente, Claudio; Johnson, Roch C.; Sopoh, Ghislain E.; Dossou, Ange D.; Colombo, Enrico
• Is Part Of: International journal of dermatology. Volume 53:Number 2(2014:Feb.)
• Page Start: 213
• Page End: 220
• Publication Date: 2013-12-10
• Subjects: Dermatology -- Periodicals; 616.5
• DOI: 10.1111/ijd.12249
• Languages: English
• ISSNs: 0011-9059

Abstract

<abstract abstract-type="main" id="ijd12249-abs-0001"> <title>Abstract</title> <sec id="ijd12249-sec-0001" sec-type="section"> <title>Objectives</title> <p>Buruli ulcer (BU) is an infected cutaneous lesion, the etiological agent of which is <italic>Mycobacterium ulcerans</italic>. Diagnosis is confirmed by the identification of acid‐fast bacilli and culture. In clinically suspicious forms with negative bacteriological or Ziehl–Neelsen (ZN) findings, molecular tests are used. This study compared the concordance of nested polymerase chain reaction (PCR) (targeting IS<italic>2404</italic>) and PCR (targeting IS<italic>2606</italic>) in different clinical situations.</p> </sec> <sec id="ijd12249-sec-0002" sec-type="section"> <title>Methods</title> <p>A total of 57 samples were sourced from 39 BU patients. Control samples (<italic>n</italic> = 43) were obtained from non‐BU ulcers in 38 patients. Samples were divided into two pieces and submitted to, respectively, histological examination and ZN staining, and PCR. Subsamples submitted to PCR were divided and submitted to nested PCR IS<italic>2404</italic> and PCR IS<italic>2606</italic>, respectively.</p> </sec> <sec id="ijd12249-sec-0003" sec-type="section"> <title>Results</title> <p>Of the 57 BU biopsies, positive results were obtained by nested PCR in 18 (31.6%) and by IS<italic>2606 </italic>PCR in 37 (64.9%) cases. Sequencing of the positive samples confirmed the specificity of amplicons in all nested PCR samples and in 26 of 37 (70.2%) samples positive to IS<italic>2606</italic>. Hence, nested PCR was more specific (100% vs. 93%) and less sensitive (32% vs. 46%) than IS<italic>2606 </italic>PCR. In the BU samples, nested PCR was negative in 15 instances, and IS<italic>2606 </italic>PCR was negative in 11 instances in which ZN histology had been positive (false negatives). Both PCRs were positive in six ZN‐negative smears.</p> </sec> <sec id="ijd12249-sec-0004" sec-type="section"> <title>Conclusions</title> <p>We considered 57 samples from 39 BU patients in various clinical stages and at different times after the beginning of therapy. These provided positive results in 18 cases with IS<italic>2404</italic> nested PCR and in 37 cases with PCR IS<italic>2606</italic>; only 26 of the latter remained positive subsequent to sequencing. Hence, even if IS<italic>2404 </italic>PCR is considered more specific, in subjects who appear to fail to respond to therapy, it is advisable to also carry out IS<italic>2606 </italic>PCR. A possible interpretation of the discordance between the two techniques due to unavoidable technical errors as well as to different sensitivity of the two tests at <italic>M. ulcerans</italic> DNA low concentration (i.e. in recent infection and in well‐treated cases) is discussed.</p> </sec> </abstract>