Molecular and epidemiologic characterization of the diphtheria outbreak in Venezuela.

In 2016, Venezuela faced a large diphtheria outbreak that extended until 2019. Nasopharyngeal or oropharyngeal samples were prospectively collected from 51 suspected cases and retrospective data from 348 clinical records was retrieved from 14 hospitals between November 2017 and November 2018. Confirmed pathogenic Corynebactrium isolates were biotyped. Multilocus Sequence Typing (MLST) was performed followed by next-generation-based core genome-MLST and minimum spanning trees were generated. Subjects between 10 and 19 years of age were mostly affected (n = 95; 27.3%). Case fatality rates (CFR) were higher in males (19.4%), as compared to females (15.8%). The highest CFR (31.1%) was observed among those under 5, followed by the 40 to 49 age-group (25.0%). Nine samples corresponded to C. diphtheriae and 1 to C. ulcerans. Two Sequencing Types (ST), ST174 and ST697 (the latter not previously described) were identified among the eight C. diphtheriae isolates from Carabobo state. Cg-MLST revealed only one cluster also from Carabobo. The Whole Genome Sequencing analysis revealed that the outbreak seemed to be caused by different strains with C. diphtheriae and C. ulcerans coexisting. The reemergence and length of this outbreak suggest vaccination coverage problems and an inadequate control strategy.

Analysis of Corynebacterium diphtheriae macrophage interaction: Dispensability of corynomycolic acids for inhibition of phagolysosome maturation and identification of a new gene involved in synthesis of the corynomycolic acid layer.

Corynebacterium diphtheriae is the causative agent of diphtheria, a toxin mediated disease of upper respiratory tract, which can be fatal. As a member of the CMNR group, C. diphtheriae is closely related to members of the genera Mycobacterium, Nocardia and Rhodococcus. Almost all members of these genera comprise an outer membrane layer of mycolic acids, which is assumed to influence host-pathogen interactions. In this study, three different C. diphtheriae strains were investigated in respect to their interaction with phagocytic murine and human cells and the invertebrate infection model Caenorhabditis elegans. Our results indicate that C. diphtheriae is able to delay phagolysosome maturation after internalization in murine and human cell lines. This effect is independent of the presence of mycolic acids, as one of the strains lacked corynomycolates. In addition, analyses of NF-κB induction revealed a mycolate-independent mechanism and hint to detrimental effects of the different strains tested on the phagocytic cells. Bioinformatics analyses carried out to elucidate the reason for the lack of mycolates in one of the strains led to the identification of a new gene involved in mycomembrane formation in C. diphtheriae.

[COMPOSITION OF POPULATION OF DIPHTHERIA CAUSATIVE AGENT STRAINS IN RUSSIA].

AIM: Characteristics of clonal composition of Corynebacterium diphtheriae strain population in Russia using MLST, as well as evaluation of a possibility of using of this method during execu- tion of monitoring of diphtheria infection causative agent strains. MATERIALS AND METHODS: C. diph- theriae strains, isolated in Russia in 1957 - 2015 and sent to Gabrichevsky MRIEM reference centre for diphtheria and pertussis, were studied. Gentyping of C. diphtheriae using MLST was carried out based on sequencing of <> gene fragments. ST identification was carried out according to PubMLST Result. C. diphtheriae strains of 36 sequence-types (ST) were identi- fied on the territory of Russia - 27 previously known and 9 novel, detected for the first time. 2 sequence types ST25 and ST8 (22% and 18%) dominated. Inter-relation between phenotype. properties (toxigenicity. and biovar) and membership of C. diphtheriae strains in certain sequence- types was shown - toxigenic and non-toxigenic C. diphtheriae strains of various biovars were characterized by certain sequence-types. Changes of clonal composition of C. diphtheriae popula- tion in dynamics of epidemic process of diphtheria infection were.shown. CONCLUSION: Use of MLST allowed to characterized clonal composition of C. diphtheriae strains' population in Russia and has shown perspectives of use of this method to characterize population of diphtheria causative agent, detect epidemically significant strains and decipher foci of diphtheria infection.

[Whole cell protein profiling characterization of Corynebacterium diphtheriae clinical isolates collected from various infections].

INTRODUCTION: Corynebacterium diphtheriae can cause various infections such as diphtheria, wound infections, septic arthritis, bacteraemia and endocarditis. Different virulence properties of the isolates might be related to different virulence factors expressed by the isolates. The objective of this study was to explore whether whole cell protein profiling might be useful in prediction of pathogenic properties of C. diphtheriae isolates. METHODS: C. disphtheriae isolates collected from diphtheria, invasive and local infections and from asymptomatic carriers in Poland, France, New Caledonia and Canada in 1950-2014 were investigated using whole cell protein profile analysis. RESULTS: All the examined isolates were divided into two clades: A and B with similarity about 47%, but clade B was represented by only one isolate. The clade A was divided in two subclades A.I NS .II with similarity 53,2% and then into four groups: A.Ia, A.Ib, A.Ic and A.Id. The comparative analysis did not distinguish clearly toxigenic and nontoxigenic isolates as well as invasive and noninvasive isolates. CONCLUSIONS: Whole cell protein profile analysis of C. diphtheria exhibits good concordance with other genotyping methods but this method is not able to distinguish clearly invasive from non-invasive isolates.

Genomic analysis of a nontoxigenic, invasive Corynebacterium diphtheriae strain from Brazil.

We report the complete genome sequence and analysis of an invasive Corynebacterium diphtheriae strain that caused endocarditis in Rio de Janeiro, Brazil. It was selected for sequencing on the basis of the current relevance of nontoxigenic strains for public health. The genomic information was explored in the context of diversity, plasticity and genetic relatedness with other contemporary strains.

Genomic analysis of a nontoxigenic, invasive Corynebacterium diphtheriae strain from Brazil

We report the complete genome sequence and analysis of an invasive Corynebacterium diphtheriae strain that caused endocarditis in Rio de Janeiro, Brazil. It was selected for sequencing on the basis of the current relevance of nontoxigenic strains for public health. The genomic information was explored in the context of diversity, plasticity and genetic relatedness with other contemporary strains.

[Multilocus sequencing of Corynebacterium diphtheriae strains isolated in Russia in 2002 - 2012].

AIM: Characterization of contemporary C. diphtheriae strains isolated in Russia by using multilocus DNA sequencing (MLST). MATERIALS AND METHODS: 28 toxigenic C. diphtheriae strains isolated in Russia in 2002-2012 and sent to diphtheria and pertussis reference center of Gabrichevsky Research Institute of Epidemiology and Microbiology were studied. C. diphtheriae strain genotyping was performed by using MLST based on atpA, dnaE, dnaK, fusA, leuA, odhA and rpoB gene fragments. Identification of alleles and ST was carried out according to EMBL/GenBank and PubMLST, eBurst approach was used for cluster analysis. RESULTS: By using MLST contemporary toxigenic C. diphtheriae strains isolated in Russia in 2002 - 2012 were characterized. 8 genotypes (ST41, ST5, ST8, ST28, ST25, ST44, ST-new1 and ST-new2) were identified, 3 among them were dominating--ST8, ST28 and ST-new1. Most of the toxigenic strains belong to biovar gravis and ST8. Among biovar mitis strains a higher heterogeneity by ST membership was noted, but with prevalence of ST28 strains. CONCLUSION: Use of MLST allowed to characterize contemporary circulating population of toxigenic C. diphtheriae strains isolated in Russia and showed perspective of application of this method for characterization of diphtheria causative agent population and detection of epidemically significant strains, as well as juxtaposing of them with genetic structure of foreign strains.

[Influence of genetic and phenotypical factors on the efficiency of the vaccination of young children against diphtheria and measles].

The child's sex was shown to influence the character of antibody formation only after immunization against diphtheria with live measles vaccine: girls exhibited stronger reaction to vaccination than boys. Children of different gender were found to have characteristic HLA DR markers of humoral immune response to diphtheria toxoid and measles vaccine. HLA DR7 proved to be the marker of low production of antibodies to diphtheria toxoid and measles vaccine in boys.

[The medico-genetic aspects in the development of postvaccinal antidiphtheria immunity]. / Nekotorye mediko-geneticheskie aspekty formirovaniia postvaktsinal'nogo protivodifteriinogo immuniteta.

The paper contains a review of relevant literature highlighting particular features of diphtheria epidemic in Ukraine. An assessment is given of potentialities of vaccination in diphtheria. It is shown that inadequate vaccination is not the only factor responsible for the epidemic. Some specificities are described of the immune response from the present-day standpoint together with the connection of this process with the system of histocompatibility. Manifestations of the immune response to the vaccination carried out are discussed, and in accordance with this principles and lines of inquiry are formulated according to modern idea of the subject.