72 research outputs found
Identification of Zoophilic Dermatophytes Using MALDI-TOF Mass Spectrometry
Dermatophytoses represent a major health burden in animals and man. Zoophilic
dermatophytes usually show a high specificity to their original animal host but a
zoonotic transmission is increasingly recorded. In humans, these infections elicit highly
inflammatory skin lesions requiring prolonged therapy even in the immunocompetent
patient. The correct identification of the causative agent is often crucial to initiate a
targeted and effective therapy. To that end, matrix assisted laser desorption ionization
time-of-flight mass spectrometry (MALDI-TOF MS) represents a promising tool. The
objective of this study was to evaluate the reliability of species identification of zoophilic
dermatophytes using MALDI-TOF MS. The investigation of isolates from veterinary clinical
samples suspicious of dermatophytoses suggests a good MALDI-TOF MS based
identification of the most common zoophilic dermatophyte Microsporum canis.
Trichophyton (T.) spp. usually achieved scores only around the cutoff value for secure
species identification because of a small number of reference spectra. Moreover, these
results need to be interpreted with caution due to the close taxonomic relationship of
dermatophytes being reflected in very similar spectra. In our study, the analysis of 50
clinical samples of hedgehogs revealed no correct identification using the provided
databases, nor for zoophilic neither for geophilic causative agents. After DNA
sequencing, adaptation of sample processing and an individual extension of the inhouse
database, acceptable identification scores were achieved (T. erinacei and
Arthroderma spp., respectively). A score-oriented distance dendrogram revealed
clustering of geophilic isolates of four different species of the genus Arthroderma and
underlined the close relationship of the important zoophilic agents T. erinacei, T.
verrucosum and T. benhamiae by forming a subclade within a larger cluster including
different dermatophytes. Taken together, MALDI-TOF MS proofed suitable for the
identification of zoophilic dermatophytes provided fresh cultures are used and the
reference library was previously extended with spectra of laboratory-relevant species.
Performing independent molecular methods, such as sequencing, is strongly
recommended to substantiate the findings from morphologic and MALDI-TOF MS
analyses, especially for uncommon causative agents
Analysis of Porcine Pro- and Anti-Inflammatory Cytokine Induction by S. suis In Vivo and In Vitro
Weaning piglets are susceptible to the invasive Streptococcus (S.) suis infection, which can result in septicemia. The aim of this study was to investigate the cytokine profile induced upon S. suis infection of blood, to determine the cellular sources of those cytokines, and to study the potential effects of the induced cytokines on bacterial killing. We measured TNF-α, IL-6, IFN-γ, IL-17A and IL-10 after an experimental intravenous infection with S. suis serotype 2 in vivo, and analyzed whole blood, peripheral blood mononuclear cells (PBMC) and separated leukocytes to identify the cytokine-producing cell type(s). In addition, we used a reconstituted whole blood assay to investigate the effect of TNF-α on bacterial killing in the presence of different S. suis-specific IgG levels. An increase in IL-6 and IL-10, but not in IFN-γ or IL-17A, was observed in two of three piglets with pronounced bacteremia 16 to 20 h after infection, but not in piglets with controlled bacteremia. Our results confirmed previous findings that S. suis induces TNF-α and IL-6 and could demonstrate that TNF-α is produced by monocytes in vitro. We further found that IL-10 induction resulted in reduced secretion of TNF-α and IL-6. Rapid induction of TNF-α was, however, not crucial for in vitro bacterial killing, not even in the absence of specific IgG
Genetic diversity of Streptococcus suis isolates as determined by comparative genome hybridization
<p>Abstract</p> <p>Background</p> <p><it>Streptococcus suis </it>is a zoonotic pathogen that causes infections in young piglets. <it>S. suis </it>is a heterogeneous species. Thirty-three different capsular serotypes have been described, that differ in virulence between as well as within serotypes.</p> <p>Results</p> <p>In this study, the correlation between gene content, serotype, phenotype and virulence among 55 <it>S. suis </it>strains was studied using Comparative Genome Hybridization (CGH). Clustering of CGH data divided <it>S. suis </it>isolates into two clusters, A and B. Cluster A isolates could be discriminated from cluster B isolates based on the protein expression of extracellular factor (EF). Cluster A contained serotype 1 and 2 isolates that were correlated with virulence. Cluster B mainly contained serotype 7 and 9 isolates. Genetic similarity was observed between serotype 7 and serotype 2 isolates that do not express muramidase released protein (MRP) and EF (MRP<sup>-</sup>EF<sup>-</sup>), suggesting these isolates originated from a common founder. Profiles of 25 putative virulence-associated genes of <it>S. suis </it>were determined among the 55 isolates. Presence of all 25 genes was shown for cluster A isolates, whereas cluster B isolates lacked one or more putative virulence genes. Divergence of <it>S. suis </it>isolates was further studied based on the presence of 39 regions of difference. Conservation of genes was evaluated by the definition of a core genome that contained 78% of all ORFs in P1/7.</p> <p>Conclusions</p> <p>In conclusion, we show that CGH is a valuable method to study distribution of genes or gene clusters among isolates in detail, yielding information on genetic similarity, and virulence traits of <it>S. suis </it>isolates.</p
A Comparative Transcriptome Analysis of Human and Porcine Choroid Plexus Cells in Response to Streptococcus suis Serotype 2 Infection Points to a Role of Hypoxia
Streptococcus suis (S. suis) is an important opportunistic pathogen, which can cause
septicemia and meningitis in pigs and humans. Previous in vivo observations in S. suisinfected
pigs revealed lesions at the choroid plexus (CP). In vitro experiments with primary
porcine CP epithelial cells (PCPEC) and human CP epithelial papilloma (HIBCPP) cells
demonstrated that S. suis can invade and traverse the CP epithelium, and that the CP
contributes to the inflammatory response via cytokine expression. Here, next generation
sequencing (RNA-seq) was used to compare global transcriptome profiles of PCPEC and
HIBCPP cells challenged with S. suis serotype (ST) 2 infected in vitro, and of pigs infected
in vivo. Identified differentially expressed genes (DEGs) were, amongst others, involved in
inflammatory responses and hypoxia. The RNA-seq data were validated via quantitative
PCR of selected DEGs. Employing Gene Set Enrichment Analysis (GSEA), 18, 28, and 21
enriched hallmark gene sets (GSs) were identified for infected HIBCPP cells, PCPEC, and
in the CP of pigs suffering from S. suis ST2 meningitis, respectively, of which eight GSs
overlapped between the three different sample sets. The majority of these GSs are
involved in cellular signaling and pathways, immune response, and development,
including inflammatory response and hypoxia. In contrast, suppressed GSs observed
during in vitro and in vivo S. suis ST2 infections included those, which were involved in
cellular proliferation and metabolic processes. This study suggests that similar cellular
processes occur in infected human and porcine CP epithelial cells, especially in terms of
inflammatory response
Comparing Cathelicidin Susceptibility of the Meningitis Pathogens Streptococcus suis and Escherichia coli in Culture Medium in Contrast to Porcine or Human Cerebrospinal Fluid
Host defense peptides or antimicrobial peptides (AMPs), e.g., cathelicidins, have
recently been discussed as a potential new treatment option against bacterial infections.
To test the efficacy of AMPs, standardized methods that closely mimic the physiological
conditions at the site of infection are still needed. The aim of our study was to
test the meningitis-causing bacteria Streptococcus suis and Escherichia coli for their
susceptibility to cathelicidins in culture medium versus cerebrospinal fluid (CSF).
Susceptibility testing was performed in analogy to the broth microdilution method
described by the Clinical and Laboratory Standard Institute (CLSI) to determine minimum
inhibitory concentrations (MICs) of antimicrobial agents. MICs were determined using
cation-adjusted Mueller–Hinton broth (CA-MHB), lysogeny broth (LB), Roswell Park
Memorial Institute medium (RPMI) or Dulbecco’s Modified Eagle’s Medium (DMEM)
(the latter two supplemented with 5% CA-MHB or blood) and compared with MICs
obtained in porcine or human CSF. Our data showed that MICs obtained in CA-MHB
as recommended by CLSI do not reflect the MICs obtained in the physiological body
fluid CSF. However, the MICs of clinical isolates of S. suis tested in RPMI medium
supplemented with CA-MHB, were similar to those of the same strains tested in CSF.
In contrast, the MICs in the human CSF for the tested E. coli K1 strain were higher
compared to the RPMI medium and showed even higher values than in CA-MHB. This
highlights the need for susceptibility testing of AMPs in a medium that closely mimics
the clinically relevant conditions
Low-Energy Electron Irradiation Efficiently Inactivates the Gram-Negative Pathogen Rodentibacter pneumotropicus—A New Method for the Generation of Bacterial Vaccines with Increased Efficacy
Bacterial pathogens cause severe infections worldwide in livestock and in humans, and antibiotic resistance further increases the importance of prophylactic vaccines. Inactivated bacterial vaccines (bacterins) are usually produced via incubation of the pathogen with chemicals such as formaldehyde, which is time consuming and may cause loss of immunogenicity due to the modification of structural components. We evaluated low-energy electron irradiation (LEEI) as an alternative method to generate a bacterin. Rodentibacter pneumotropicus, an invasive Gram-negative murine pathogen, was inactivated with LEEI and formaldehyde. LEEI resulted in high antigen conservation, and LPS activity was significantly better maintained when compared with formaldehyde treatment. Immunization of mice with LEEI-inactivated R. pneumotropicus elicited a strong immune response with no detectable bacterial burden upon sublethal challenge. The results of this study suggest the inactivation of bacteria with LEEI as an alternative, fast and efficient method to generate bacterial vaccines with increased efficacy
The immunoglobulin M-degrading enzyme of Streptococcus suis, Ide Ssuis , is involved in complement evasion
A critical review on experimental Streptococcus suis infection in pigs with a focus on clinical monitoring and refinement strategies
Abstract Streptococcus suis (S. suis) is a major pig pathogen worldwide with zoonotic potential. Though different research groups have contributed to a better understanding of the pathogenesis of S. suis infections in recent years, there are still numerous neglected research topics requiring animal infection trials. Of note, animal experiments are crucial to develop a cross-protective vaccine which is highly needed in the field. Due to the severe clinical signs associated with S. suis pathologies such as meningitis and arthritis, implementation of refinement is very important to reduce pain and distress of experimentally infected pigs. This review highlights the great diversity of clinical signs and courses of disease after experimental S. suis pig infections. We review clinical read out parameters and refinement strategies in experimental S. suis pig infections published between 2000 and 2021. Currently, substantial differences exist in describing clinical monitoring and humane endpoints. Most of the reviewed studies set the body temperature threshold of fever as high as 40.5°C. Monitoring intervals vary mainly between daily, twice a day and three times a day. Only a few studies apply scoring systems. Published scoring systems are inconsistent in their inclusion of parameters such as body temperature, feeding behavior, and respiratory signs. Locomotion and central nervous system signs are more common clinical scoring parameters in different studies by various research groups. As the heterogenicity in clinical monitoring limits the comparability between studies we hope to initiate a discussion with this review leading to an agreement on clinical read out parameters and monitoring intervals among S. suis research groups
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