Contemporary microbiology and identification of Corynebacteria spp. causing infections in human.

The 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, semi-automated 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. 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.

Sequence variation in virulence-related genes of Bordetella pertussis isolates from Poland in the period 1959-2013.

This study aimed to characterise Bordetella pertussis isolates circulating in Poland since 1959. Sequence analysis of ptxA, ptxC, prn, tcfA, fim2, fim3 and ptxP for 175 clinical isolates and currently and previously used vaccine strains was performed. Clinical isolates from the period 1995-2013 were found to be different to three currently used vaccine strains harbouring the allelic combination ptxA2-ptxC1-ptxP1-prn1-tcfA2-fim2-1-fim3-1, seen frequently in Poland in the early pertussis vaccination period but not found after 1995. Generally, among B. pertussis isolates from the period 2000-2013, two genotypes predominated, ptxA1-ptxC1-ptxP1-prn1-tcfA2-fim2-2-fim3-1 and ptxA1-ptxC1-ptxP1-prn2-tcfA2-fim2-1-fim3-1, with frequencies of 45% and 32.5%, respectively. The isolates harbouring ptxA1-ptxC2-ptxP3-prn2-tcfA2-fim2-1-fim3-2 and ptxA1-ptxC2-ptxP3-prn2-tcfA2-fim2-1-fim3-1 profiles, currently highly prevalent within other European Union (EU) countries, were rarely found in Poland, as they circulated in the period 2000-2013 with frequencies of 10% and 5%, respectively. We hypothesise that several previous changes of strain composition in whole-cell pertussis vaccine produced locally and used since 1960 in Poland resulted in a more diverse immune pressure in the population, resulting in different prevalence of alleles compared to elsewhere.

Analysis of Bordetella pertussis clinical isolates circulating in European countries during the period 1998-2012.

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.