Relapsing Aspergillus niger (An) Otomycosis is Caused by a Single Persistent Genotype

R. R. KLONT, S. J. M. STRIJBOSCH, W. J. G. MELCHERS, P. E. VERWEIJ

Author address: 

University Medical Center Nijmegen, Nijmegen, Netherlands

Abstract: 

Background: Otomycosis is mainly caused by An and tends to recur despite long-term treatment. It is unknown whether patients become reí¯nfected with different An strains or that a strain persists and gives rise to clinical relapses. We investigated the genetic variability of An strains obtained from patients with recurrent otomycosis using RAPD-PCR. Methods: Seven An strains from 2 patients (4 and 3 strains resp.) with recurrent otomycosis were genotyped. These strains were recovered from one ear over a period of 5 years in one patient and 2 months in the other. RAPD-PCR was performed with four different primers: 114.2 (Eric II: 5’-AAGTAAGTGACTGGGGTGAGCG-3’), 129.11 (Asp R108: 5’GTATTGCCCT-3’), 129.21 (5’-GCGCACGG-3’) and 129.22 (5’-GCTGGTGG-3’). Banding patterns were detected by electrophoresis in agarose gel, photographed and interpreted by visual inspection. Five unrelated An strains from 5 patients with otomycosis and one strain each of A.flavus, A.fumigatus and Rhizomucor pussilus were used as controls. All isolates were cultured in Sabouraud’s dextrose broth for 18 hours in shaking conditions at 37°C. Cultures were filtrated using 0.8μm filters and beaded with the MagNa Lyser. Results: Primers 114.2, 129.21 and 129.22 differentiated the An isolates with high resolution. In addition, all An strains could be differentiated from A.flavus, A.fumigatus and R.pussilus. However, primer 129.21 resulted in the best discriminative banding patterns. In each patient the recurrent episodes of otitis were caused by a single genotype. Conclusions: Using RAPD-PCR it was shown that recurrent episodes of otomycosis were caused by a single An genotype indicating persistence of the fungus rather than reí¯nfection.
2004

abstract No: 

M-1049-200

Full conference title: 

44th Interscience Conference on Antimicrobial Agents and Chemotherapy
    • ICAAC 44th