Geographically Diverse Clusters of Nontoxigenic Corynebacterium diphtheriae Infection, Germany, 2016–2017

• DOI: 10.3201/eid2407.172026
• Publication Date: 2018-06-12T18:13:31Z
• Authors: Alexandra Dangel; Anja Berger; Regina Konrad; Heribert Bischoff; Andreas Sing
• Keywords: Male; Infectious and parasitic diseases; RC109-216; History, 21st Century; Polymorphism, Single Nucleotide; Disease Outbreaks; 03 medical and health sciences; Germany; Humans; Public Health Surveillance; diphtheria; bacteria; 0303 health sciences; drug users; Corynebacterium Infections; Whole Genome Sequencing; Research; Corynebacterium diphtheriae; molecular typing; R; 3. Good health; bacterial infections; disease outbreaks; Medicine; Female; Genome, Bacterial; Multilocus Sequence Typing

From 2016 through the middle of 2017, the German Consiliary Laboratory on Diphtheria noted an increase in nontoxigenic Corynebacterium diphtheriae isolates submitted from cities in northern Germany. Many patients for whom epidemiologic data were available were homeless, alcohol or drug abusers, or both. After performing routine diagnostics and multilocus sequence typing (MLST), we analyzed isolates of sequence type (ST) 8 and previously submitted isolates by whole-genome sequencing. Results were analyzed for phylogenetic relationship by core genome MLST (cg-MLST) and whole-genome single-nucleotide polymorphism profiles. Next-generation sequencing-based cg-MLST revealed several outbreak clusters caused by ST8; the geographic focus was in the metropolitan areas of Hamburg and Berlin. To achieve enhanced analytical depth, we used additional cg-MLST target genes and genome-wide single-nucleotide polymorphisms. We identified patient characteristics and detected transmission events, providing evidence that nontoxigenic C. diphtheriae infection is a potential public health threat in industrialized countries.