Despite more than 50 years of vaccination, pertussis is still an endemic disease, with regular epidemic outbreaks. With the exception of Poland, European countries have replaced whole-cell vaccines (WCVs) by acellular vaccines (ACVs) in the 1990s. Worldwide, antigenic divergence in vaccine antigens has been found between vaccine strains and circulating strains. In this work, 466 Bordetella pertussis isolates collected in the period 1998–2012 from 13 European countries were characterised by multi-locus antigen sequence typing (MAST) of the pertussis toxin promoter (ptxP) and of the genes coding for proteins used in the ACVs: pertussis toxin (Ptx), pertactin (Prn), type 2 fimbriae (Fim2) and type 3 fimbriae (Fim3). Isolates were further characterised by fimbrial serotyping, multi-locus variable-number tandem repeat analysis (MLVA) and pulsed-field gel electrophoresis (PFGE). The results showed a very similar B. pertussis population for 12 countries using ACVs, while Poland, which uses a WCV, was quite distinct, suggesting that ACVs and WCVs select for different B. pertussis populations. This study forms a baseline for future studies on the effect of vaccination programmes on B. pertussis populations.Electronic supplementary materialThe online version of this article (doi:10.1007/s10096-014-2297-2) contains supplementary material, which is available to authorized users.

Significance and Impact of the Study: The number of opportunistic infections caused by Corynebacteria is increasing due to increase in number of immunocompromised patients. New Corynebacterium species and new human infections, caused by this group of bacteria, has been described recently. However, identification of Corynebacteria is still a challenge despite application of sophisticated laboratory methods. In the study we present possibilities and limitations of various commercial systems for identification of Corynebacteria. AbstractThe Corynebacterium is a genus of bacteria of growing clinical importance. Progress in medicine results in growing population of immunocompromised patients and growing number of infections caused by opportunistic pathogens. A new infections caused by new Corynebacterium species and species previously regarded as commensal micro-organisms have been described. Parallel with changes in Corynebacteria infections, the microbiological laboratory diagnostic possibilities are changing. But identification of this group of bacteria to the species level remains difficult. In the paper, we present various manual, semiautomated and automated assays used in clinical laboratories for Corynebacterium identification, such as API Coryne, RapID CB Plus, BBL Crystal Gram Positive ID System, MICRONAUT-RPO, VITEK 2, BD Phoenix System, Sherlock Microbial ID System, MicroSeq Microbial Identification System, Biolog Microbial Identification Systems, MALDI-TOF MS systems, polymerase chain reaction (PCR)-based and sequencing-based assays. The presented assays are based on various properties, like biochemical tests, specific DNA sequences, composition of cellular fatty acids, protein profiles and have specific limitations.

In the present study, clinical isolates of Bordetella pertussis collected in Poland from 1960 to 2005 were analyzed by pulsed-field gel electrophoresis (PFGE) according to protocols recommended in previous studies. Among the 110 isolates from 1995 to 2005, 59 PFGE patterns were found, most of which were different from those currently circulating in other European Union (EU) countries for which data are available. The PFGE patterns of currently disseminating B. pertussis clones were found within PFGE groups III and IV, as elsewhere in the EU, and in newly identified clusters A and C. Up to 70, 26, and 4%, respectively, of the currently isolated strains in Poland harbored ptxA1-prn1, ptxA1-prn2, and ptxA1-prn3 allele combinations, and most (82%) were found to be of the Fim2 phenotype. Differences in the extent of heterogeneity estimated by PFGE typing in B. pertussis populations circulating in Poland in comparison to other EU countries may be due to the different vaccine composition strategy, since routine pertussis vaccination was initiated in Poland in 1960.

Only three Corynebacterium species are known to produce a lethal exotoxin called diphtheria toxin. These are C. diphtheriae, C. ulcerans and C. pseudotuberculosis. The diphtheria toxin gene (tox) is carried in a family of closely related corynebacteriophages and therefore the toxin can be produced only through lysogenisation, in which the corynephage encoding tox is stably inserted into the chromosome. However, ‘nontoxigenic tox gene-bearing’ (NTTB) strains, which are genotypically tox-positive but do not express the protein, have been described. The emergence of NTTB strains was first observed during the 1990s diphtheria epidemic in Eastern Europe and nowadays such isolates have been detected in many countries in the world. Recently, novel species of Corynebacterium genus have been described which might have the potential of producing the diphtheria toxin due to the possession of the diphtheria toxin gene but it has not produced toxin in laboratory tests. The circulation of NTTB strains could be related to the increased risk for diphtheria disease arising from the risk of re-emerging toxin expression. The article presents the mechanism of diphtheria toxin expression and action, recently described novel species of NTTB corynebacteria as well as the taxonomic changes within the C. diphtheriae group.

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