Possible human-to-human transmission of toxigenic Corynebacterium ulcerans.

Toxigenic Corynebacterium ulcerans is an emerging cause of diphtheria. In contrast to the classical diphtheria pathogen C. diphtheriae, human-to-human transmission of this primarily zoonotic pathogen has not been clearly documented. Here we report on a two-person cluster suggesting an initial zoonotic and a subsequent human-to-human transmission event.

Eosinophilic granuloma with Splendore-Hoeppli material caused by toxigenic Corynebacterium ulcerans in a heifer.

Raised lesions were present on the left nasal vestibule of a 20-month-old Japanese Brown heifer. The largest mass which caused partial nasal obstruction was removed surgically. Corynebacterium ulcerans was identified in the mass. 16S ribosomal RNA and RNA polymerase beta subunit genes were 100% and 98% identical to other C. ulcerans strains. Histologically, multiple foci of eosinophilic granuloma with Splendore-Hoeppli material were seen. Rod-shaped Gram-positive organisms were detected with metachromatic granules, producing diphtheria toxin with 5, 30 and 48 amino acid differences to another C. ulcerans strain, C. diphtheriae or C. pseudotuberculosis, respectively. The toxin is highly cytotoxic and may be responsible for the formation of abundant Splendore-Hoeppli material. The lesion was therefore judged to be an allergic reaction to bacterial antigens or diphtheria toxin.

Use of imaged capillary isoelectric focusing technique in development of diphtheria toxin mutant CRM197.

Polysaccharide based-vaccines have been successful in providing protection in adults from bacterial infections, however they are not as effective in infants or young children. To enhance the immune response in these high risk groups, the polysaccharide is conjugated with a carrier protein such as cross-reacting material 197 (CRM197). The CRM197 protein has been well-characterized biochemically and biophysically using various analytical techniques however, none of these have been CE-based methods. Of the various CE techniques, imaged capillary isoelectric focusing (icIEF) is a method that has been used extensively in the field of protein-based drug development as a tool for product identification, stability monitoring, and characterization. Applications of icIEF technique using Convergent Bioscience icIEF instrumentation with whole-field imaging technology are presented and discussed in this paper. These applications include rapid method development to establish a CRM197 identity test for product release, a concentration assay for upstream and downstream in-process product development, and CRM197 stability with respect to its charge heterogeneity under accelerated temperature stress. The data presented demonstrates the utility of the icIEF method as a multifunctional assay because it can screen for better product candidates during early stage clonal selection as well as support in-process and final product characterization throughout CRM197 development.

Diphtheria Antibodies and T lymphocyte Counts in Patients Infected with HIV-1

We assessed the IgG levels anti-diphtheria (D-Ab) and T cell counts (CD4+ and CD8+) in HIV-1 infected subjects undergoing or not highly active antiretroviral therapy (HAART). Approximately 70% of all HIV-1 patients were unprotected against diphtheria. There were no differences in D-Ab according to CD4 counts. Untreated patients had higher D-Ab (geometric mean of 0.62 IU/ml) than HAART-patients (geometric mean of 0.39 IU/ml). The data indicated the necessity of keeping all HIV-1 patients up-to-date with their vaccination.

[Monoclonal antibodies labeled with colloidal gold for immunochromatographic express analysis of diphtheria toxin].

One-step rapid immunochromatographic method for detection of diphtheria toxin in different water samples (phosphate buffer, milk, human nasopharyngeal swab) with the conjugate of monoclonal antibodies labeled with colloidal gold was developed. The limit of visible detection of the diphtheria toxin is 10 ng/ml and 15 min time analysis. The use of silver sensitivity enhancement and scanning equipment decreased the detection limit to 1.25 ng/ml.

[Micro technologies in express diagnostics of toxigenic Corynebacterium diphtheriae strains].

AIM: Development of micro technologies based approach for express diagnostics of toxigenic C. diphtheriae strains. MATERIALS AND METHODS: Corynebacterium diphtheriae 10648 (tox+) and C. diphtheriae NCTC 10356 (tox-) from Central Health Laboratory (London) reference strains were used as positive and negative controls respectively. Diagnostic kit was created by using fractions of antibodies with high avidity that were obtained by consecutive fractioning of positive antitoxic blood sera and then loaded onto polyacrylamide latex particles with the diameter of 0.81 microm. 20 Elek test positive C. diphtheriae strains and 20 tox gene PCR negative C. diphtheriae strains (i.e. non toxigenic) (Pasteur Research Institute of Epidemiology and Microbiology) were used as control. Indirect hemagglutination with anti-diphtheria antibody diagnostic kit was used as a quantitative control. PCR, Elek test and ICS test were used as quality control. RESULTS: The diagnostic kit obtained had specificity of 97%, sensitivity of 98%. Specimen preparation time is 15 - 20 minutes, reaction time - 2 - 3 minutes, and up to 93 specimens can be analyzed on a single microchip. CONCLUSION: The developed approach has high sensitivity and specificity, is easy to use, and fast in regard to preparation and reaction time. Portability of the apparatus allows the use of reagents in micro volumes.

Matrix-assisted laser desorption/ionisation time-of-flight (MALDI-TOF) mass spectrometry as a tool for rapid diagnosis of potentially toxigenic Corynebacterium species in the laboratory management of diphtheria-associated bacteria.

The rapid identification of the potentially toxigenic Corynebacterium species, C. diphtheriae, C. ulcerans and C. pseudotuberculosis is essential for diagnosis and treatment of diphtheria and diphtheria-like diseases. We used matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDIT-OF MS) in comparison with classical microbiological and molecular methods on 116 Corynebacterium strains. All 90 potentially toxigenic Corynebacterium strains collected by the German National Consiliary Laboratory on Diphtheria in a period of more than ten years were correctly identified by MALDI-TOF MS. We propose an algorithm for fast and reliable diagnosis of diphtheria incorporating MALDI-TOF MS, real-time tox PCR and Elek testing.

[Immunochromatographic and latex-agglutination systems for diphtheria toxin detection].

The use of two monoclonal antibody types specific to different epitopes of diphtheria toxin systems have been developed to reveal diphtheria corynebacteria toxigenicity rapidly based on immunochromatographic and latex-agglutination detection of the diphtheria toxin. The methods have been tested on a sample of 36 clinical isolates. The possibility of significant detection of the toxigenic properties of the Corynebacterium strain, grown for 1 day, has been demonstrated. The developed methods allow for the detection of diphtheria toxin in concentrations of 3-4 ng/ml. The developed test systems are a perspective tool for diphtheria diagnostics because of significant time shortening as compared to traditional microbiological methods.

[Production and characteristics of monoclonal antibodies to the diphtheria toxin].

Monoclonal antibodies to the diphtheria toxin were produced without cross reactivity with the thermolabile toxin (LT) from Escherichia coli; ricin; choleraic toxin; the SeA, SeB, SeE, SeI, and SeG toxins of staphylococcus; the lethal factor of the anthrax toxin; and the protective antigen of the anthrax toxin. A pair of antibodies for the quantitative determination of the diphtheria toxin in the sandwich variation of enzyme-linked immunosorbent assay (ELISA) was chosen. The determination limit of the toxin was 0.7 ng/ml in plate and 1.6 ng/ml in microchip ELISA. The presence of a secretion from the nasopharynx lavage did not decrease the sensitivity of the toxin determination by sandwich ELISA. The immunization of mice with the diphtheria toxin and with a conjugate of the diphtheria toxin with polystyrene microspheres demonstrated that the conjugate immunization resulted in the formation of hybridoma clones which produced antibodies only to the epitopes of the A fragment of the diphtheria toxin. The immunization with the native toxin caused the production of hybridoma clones which predominantly produced antibodies to the epitopes of the B fragment.

Development of a biological test to evaluate the bioavailability of iron in culture media.

AIMS: To develop an easy-to-use and pathogen-free protocol giving reliable information on the bioavailability of iron in a medium. METHODS AND RESULTS: In aerobic conditions, iron bioavailability is very low, and most of its forms cannot be assimilated by micro-organisms. Media with similar iron contents can differ considerably in iron bioavailability, something that is not easily achieved using conventional physicochemical methods. The assay developed in the present work is based on a pyoverdin siderophore release by fluorescent Pseudomonas in response to iron stress. CONCLUSIONS: The test was applied to a complex medium used for the production of diphtheria toxin (DT). A significant difference between the bioavailable iron level and the total chemical concentrations contributed by the various compounds used to make the medium could thus be detected. This can be explained by the formation of salt complexes trapping the iron, which thus cannot be used directly by the micro-organism for its metabolism. SIGNIFICANCE AND IMPACT OF THE STUDY: The assay can easily be applied to any medium designed for the production of iron-regulated compounds. This is particularly useful when dealing with processes that use pathogenic strains as was shown in the case based on DT production.

Vacunación antidiftérica / No disponible

No disponible

Analysis of toxigenic Corynebacterium ulcerans strains revealing potential for false-negative real-time PCR results.

Diphtheria surveillance depends on the rapid and reliable recognition of the toxin gene in Corynebacterium diphtheriae. Real-time PCR is a rapid tool to confirm the presence of the diphtheria toxin gene (tox) in an isolate or specimen. We report that some toxigenic Corynebacterium ulcerans strains show atypical results in a real-time PCR for tox.

Quantification of diphtheria toxin mediated ADP-ribosylation in a solid-phase assay.

BACKGROUND: Because of reduced vaccination programs, the number of diphtheria infections has increased in the last decade. Diphtheria toxin (DT) is expressed by Corynebacterium diphtheriae and is responsible for the lethality of diphtheria. DT inhibits cellular protein synthesis by ADP-ribosylation of the eukaryotic elongation factor 2 (eEF2). No in vitro system for the quantification of DT enzymatic activity exists. We developed a solid-phase assay for the specific detection of ADP-ribosylation by DT. METHODS: Solid phase-bound his-tag eEF2 is ADP-ribosylated by toxins using biotinylated NAD(+) as substrate, and the transferred biotinylated ADP-ribose is detected by streptavidin-peroxidase. DT enzymatic activity correlated with absorbance. We measured the amount of ADP-ribosylated eEF2 after precipitation with streptavidin-Sepharose. Quantification was done after Western blotting and detection with anti-his-tag antibody using an LAS-1000 System. RESULTS: The assay detected enzymatically active DT at 30 ng/L, equivalent to 5 mU/L ADP-ribosylating activity. Pseudomonas exotoxin A (PE) activity was also detected at 100 ng/L. We verified the assay with chimeric toxins composed of the catalytic domain of DT or PE and a tumor-specific ligand. These chimeric toxins revealed increased signals at 1000 ng/L. Heat-inactivated DT and cholera toxin that ADP-ribosylates G-proteins did not show any signal increase. CONCLUSIONS: The assay may be the basis for the development of a routine diagnostic assay for the detection of DT activity and highly specific inhibitors of DT.

[Use of monoclonal antibodies against horse immunoglobulin in an enzyme immunoassay of bacterial toxins and anatoxins].

Immunization of BALB/c mice by horse antiserum against diphtheria made it possible to obtain IgG1 monoclonal antibodies (MoAbs) 2B7E4 specific for light chains of horse immunoglobulin (Ig). Unlike commercial preparations of anti-horse immunoglobulin antibodies, which are specific for the whole Ig molecule or its Fc-fragment, the peroxidase (HRP) conjugate of the MoAb, 2B7E4-HRP did not interact with human, mouse, rabbit, and sheep Igs, or horse albumin. The conjugate obtained was used with MoAbs against bacterial toxins and commercial horse anatoxins, as a universal reagent in sandwich enzyme immunoassay (ELISA) for bacterial toxins and anatoxins. The detection sensitivity of diphtheria toxin/anatoxin equaled 0.0005 Lf/ml; tetanus toxin and anatoxin were detected with sensitivities of 20 LD50/ml and 0.005 UI/ml, respectively. A similar sandwich ELISA for botulinum anatoxins (group measurement) allowed types A, B, and E to be detected at 0.02, 0.002, and 0.001 UI/ml, respectively; selective measurement was only possible in the case of type E anatoxin (0.001 UI/ml).

[Pathogenicity of Corynebacterium diphtheriae circulating in Rostov-on-Don City and Rostov region during interepidemic period].

Main pathogenic characteristics (toxin production, tox-gene detection, adhesiveness) of 59 strains of C. diphtheriae circulating in Rostov-on-Don city and Rostov region in 2004-2005 were studied. Study of toxigenicity of 15 tox+ C.di phtheriae strains showed full coincidence of Elek immunoprecipitation test and polymerase chain reaction (PCR). Presence of part of A-fragment of tox-gene was detected in 5 (11.4%) of 44 C. diphtheriae strains that were negative in Elek test. Hemagglutinating activity of toxin producing strains was intermediate (40%) or high (60%). Among non-toxigenic strains those with intermediate adhesiveness were predominated (45,5%), the intermediate or high adhesiveness was detected in strains positive in PCR. Obtained characteristics of C. diphtheriae can be useful for surveillance for diphtheria infection during interepidemic period.

Simultaneous multicolor detection system of the single-molecular microbial antigen with total internal reflection fluorescence microscopy.

Immunological diagnostic methods have been widely performed and showed high performance in molecular and cellular biology, molecular imaging, and medical diagnostics. We have developed novel methods for the fluorescent labeling of several antibodies coupled with fluorescent nanocrystal QDs. In this study we demonstrated that two bacterial toxins, diphtheria toxin and tetanus toxin, were detected simultaneously in the same view field of a cover slip by using directly QD-conjugated antibodies. We have succeeded in detecting bacterial toxins by counting luminescent spots on the evanescent field with using primary antibody conjugated to QDs. In addition, each bacterial toxin in the mixture can be separately detected by single excitation laser with emission band pass filters, and simultaneously in situ pathogen quantification was performed by calculating the luminescent density on the surface of the cover slip. Our results demonstrate that total internal reflection fluorescence microscopy (TIRFM) enables us to distinguish each antigen from mixed samples and can simultaneously quantitate multiple antigens by QD-conjugated antibodies . Bioconjugated QDs could have great potentialities for in practical biomedical applications to develop various high-sensitivity detection systems.

Immunochromatographic strip test for rapid detection of diphtheria toxin: description and multicenter evaluation in areas of low and high prevalence of diphtheria.

An immunochromatographic strip (ICS) test was developed for the detection of diphtheria toxin by using an equine polyclonal antibody as the capture antibody and colloidal gold-labeled monoclonal antibodies specific for fragment A of the diphtheria toxin molecule as the detection antibody. The ICS test has been fully optimized for the detection of toxin from bacterial cultures; the limit of detection was approximately 0.5 ng of diphtheria toxin per ml within 10 min. In a comparative study with 915 pure clinical isolates of Corynebacterium spp., the results of the ICS test were in complete agreement with those of the conventional Elek test. The ICS test was also evaluated for its ability to detect toxigenicity from clinical specimens (throat swabs) in two field studies conducted within areas of the former USSR where diphtheria is epidemic. Eight hundred fifty throat swabs were examined by conventional culture and by use of directly inoculated broth cultures for the ICS test. The results showed 99% concordance (848 of 850 specimens), and the sensitivity and specificity of the ICS test were 98% (95% confidence interval, 91 to 99%) and 99% (95% confidence interval, 99 to 100%), respectively.