Fig. 1From: Changes in MLST profiles and biotypes of Corynebacterium diphtheriae isolates from the diphtheria outbreak period to the period of invasive infections caused by nontoxigenic strains in Poland (1950–2016)Distribution of C. diphtheriae biotypes in different time periods with consideration of toxigenicity of the isolates (n – number of isolates included in the study)Back to article page