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

Abstract

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.

Corynebacterium silvaticum sp. nov., a unique group of NTTB corynebacteria in wild boar and roe deer

“…strains from caseous lymph node abscesses from wild boar (Sus scrofa, n=33) and roe deer (Capreolus capreolus, n=1) were collected between 1997 and 2018 and subjected to a comprehensive characterization including toxigenicity testing. All strains were isolated from free-roaming silvatic animals from different parts of Germany and have been published in previous case reports and studies ( [11,[14][15][16][18][19][20][21][22][23]; Table S1, available in the online version of this article). Initial isolation procedures were based on standard microbiological methods.…”

“…WGS was done on a MiSeq with 2×250 bp PE reads after Nextera XT library preparation (both Illumina, San Diego, USA) and DNA extraction on the Promega Maxwell system, as described earlier [11]. WGS raw data is available at NCBI sequence read archive (SRA) at https://www.…”

“…in Table S6) were used as query sequences for target scheme definition with the SeqSphere+target definer tool [61]. Typing with the resulting scheme of 193 pangenomic target loci was performed as described earlier [11], using the WGS data of all C. ulcerans, C. pseudotuberculosis and C. silvaticum sp. nov. from this study including KL0182 T and public genomes of C. ulcerans NCTC 7910 T and C. pseudotuberculosis ATCC 19410 T (Fig.…”

“…Multi locus sequence typing (MLST) is one of the most common tools for molecular typing [5,6], widely used for C. diphtheriae [7] and C. ulcerans [8] and implemented for delineating species within bacterial genera [9]. Currently, whole genome sequencing (WGS) offers the highest molecular resolution and is increasingly used for typing and phylogenetic classification of various pathogens, including corynebacteria [10][11][12][13].…”

Application of loop-mediated isothermal amplification combined with colorimetric and lateral flow dipstick visualization as the potential point-of-care testing for Corynebacterium diphtheriae

“…Moreover, there have been many cases being described involving C. diphtheriae and C. ulcerans, which do not fit the WHO definition of diphtheria. These cases include serious invasive infection with high mortality rates caused by nontoxigenic strains of C. diphtheriae as well as cutaneous infections, such as non-healing ulcers, caused by toxigenic and non-toxigenic C. diphtheriae [10,11,[17][18][19], whereas WHO diphtheria case definition cover only an illness of the upper respiratory tract characterized by the following: pharyngitis, nasopharyngitis, tonsillitis or laryngitis and adherent pseudomembrane of the pharynx, tonsils, larynx and/or nose [20].…”