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.

Comparison of eleven commercially available rapid tests for detection of Bacillus anthracis, Francisella tularensis and Yersinia pestis.

UNLABELLED: Yersinia pestis, Bacillus anthracis and Francisella tularensis cause serious zoonotic diseases and have the potential to cause high morbidity and mortality in humans. In case of natural outbreaks and deliberate or accidental release of these pathogens rapid detection of the bacteria is crucial for limitation of negative effects of the release. In the present study, we evaluated 11 commercially available rapid test kits for the detection of Y. pestis, B. anthracis and F. tularensis in terms of sensitivity, specificity and simplicity of the procedure. The results revealed that rapid and easy-to-perform lateral flow assays for detection of highly pathogenic bacteria have very limited sensitivity. In contrast, the immunofiltration assays showed high sensitivity but limited specificity and required a too complicated procedure to be applied in the field by nonlaboratory workers (e.g. First Responders like fire, police and emergency medical personnel). Each sample - whether tested negative or positive by the rapid tests - should be retested in a reference laboratory using validated methods. SIGNIFICANCE AND IMPACT OF THE STUDY: Rapid detection of highly pathogenic bacteria causing anthrax, plague and tularemia is crucial for the limitation of negative effects of a potential release (natural, accidental or deliberate). In the study, commercially available rapid tests for detection of Bacillus anthracis, Yersinia pestis and Francisella tularensis were investigated in terms of sensitivity, specificity and ease-to-perform. The study showed problems which could be faced during testing and results interpretation. Conclusions from this study should be helpful not only in selection of the most appropriate test for particular group of First Responders but also in undertaking decisions in situation of a contamination suspicion which have high social and economical impacts.

The utility of the PCR melting profile technique for typing Corynebacterium diphtheriae isolates.

UNLABELLED: Selection of appropriate typing method depends on a number of factors, including the scale of the investigation, the rapidity required of the results and the financial and technical resources available. Several typing methods have been applied to Corynebacterium diphtheriae genotyping, but most are laborious and time-consuming or require expensive equipment. We report an evaluation of the utility of the PCR melting profile technique for simple and easy-to-perform genotyping of C. diphtheriae. We compared the method with ribotyping-the 'gold standard' for C. diphtheriae typing-and PFGE, MLST, AFLP, RAPD and spoligotyping. SIGNIFICANCE AND IMPACT OF THE STUDY: Occurrence of Corynebacterium diphtheriae infections-in the form of diphtheria in endemic countries and in the form of invasive infections in countries with high antidiphtheria vaccination coverage-indicates the need for maintenance of ability to genotype this pathogen by laboratories. Application of an appropriate typing method is essential not only in outbreak investigations for understanding and predicting epidemics but also in monitoring of the evolution and spread of epidemic clones of C. diphtheriae. The PCR melting profile method presented in the study is a good alternative for C. diphtheriae typing.

Comparison of seven commercial enzyme-linked immunosorbent assays for the detection of anti-diphtheria toxin antibodies.

Determination of immune status of patients to diphtheria toxin is based mainly on the results of commercially available ELISA kits. The aim of the present study was to compare the results obtained by ELISAs from seven different manufacturers: Mikrogen, Immunolab, Sekisui Virotech, NovaTec, Virion\Serion, IBL International and Euroimmun. All assays were performed according to the manufacturers' instructions. The concentrations of the anti-diphtheria toxin antibodies in 72 serum samples were calculated on the basis of curves constructed from standards supplied by manufacturers and the new reference material-International Standard for Diphtheria Antitoxin (10/262). The repeatability and reproducibility of all the ELISA kits tested were good. Number of sera with concentrations of the anti-diphtheria toxin antibodies below the WHO-recommended level of protection (0.1 IU/ml) were dependent on the ELISA used: Mikrogen, 20/72 samples (27.7%); Immunolab, 11/72 samples (15.3%); Sekisui Virotech, 0/72 samples (0%); NovaTec 18/72 samples (25.0%); Serion 12/72 samples (16.7%); IBL International, 7/72 samples (9.7 %); and Euroimmun, 17/72 samples (23.6%). However, the results obtained in particular ELISAs, with the exception of Sekisui Virotech, were much more consistent when the concentrations of the anti-diphtheria toxin antibodies in 72 sera measured by using curves constructed from the International Standard 10/262. The data obtained clearly demonstrated that manufacturer-dependent differences between anti-diphtheria IgG ELISA kits exist. The differences in recommendations accepted by the individual manufacturers together with differences shown in our studies in sensitivity greatly affect the clinical interpretation of results.