Novel macroarray-based method of Corynebacterium diphtheriae genotyping: evaluation in a field study in Belarus

In this study, we evaluated a novel macroarray-based spoligotyping method for Corynebacterium diphtheriae strain typing. A total of 20 C. diphtheriae biotype gravis toxigenic isolates collected in Belarus from suspected foci of diphtheria infection (diphtheria cases, carriers, or contacts) were subjected to DNA fingerprinting. All strains had an identical ribotyping profile that was identified as ribotype 'Rossija' by comparison with the international ribotype database at the Institut Pasteur of Paris. A spoligotyping method based on simultaneous reverse-hybridization analysis of two CRISPR (clustered, regularly interspaced short palindromic repeats) loci differentiated these strains into three spoligotypes. Comparison of the spoligotyping results with the epidemiological linkage network helped us to resolve suspected links in the chains of transmission. To conclude, the C. diphtheriae spoligotyping method demonstrated its utility in the field study, in particular, underlining the importance of the use of both CRISPR loci. The generated discrete data can be presented in digital binary format and be easily exchanged between laboratories and stored in local and global databases.