Comparative analysis of pathogenic oral streptococci isolates using a virulencefactor based DNA-Microarray

Der Begriff Oralstreptokokken beschreibt zwölf Arten der Gattung Streptococcus, die zur natürlichen Mundraumflora des Menschen gehören. Verletzungen der oralen Schleimhäute und Gewebe verschaffen den Oralstreptokokken Zugang zum Blutkreislauf und somit auch zu anderen Bereichen des menschlichen Körpers, wo sie ein beachtliches pathogenes Potential entfalten können. Die bakteriellen Faktoren, die es den verschiedenen Oralstreptokokkenarten ermöglichen, medizinische Implantate und Gewebestrukturen zu kolonisieren, aber auch im Blutstrom zu persistieren, sind weitgehend unbekannt. Ziel der vorliegenden Arbeit war die Entwicklung eines speziesübergreifenden DNS-Microarraysystems zur Analyse klinischer Oralstreptokokkenisolate in Bezug auf Vorkommen und Verteilung bekannter Pathogenitätsfaktoren aus Oralstreptokokken, sowie homologer Virulenzmechanismen aus obligat pathogenen Streptokokkenarten. Eine Sammlung von 45 klinischen Oralstreptokokkenisolaten wurde mit Hilfe des entwickelten Microarraysystems analysiert. Clusteranalysen der normalisierten Signale bewiesen die Anwendbarkeit des Microarrays als Methode zur bakteriellen Speziestypisierung und verschafften darüber hinaus einen tiefergehenden Einblick in die phylogenetischen Beziehungen innerhalb der Gruppe der Oralstreptokokken. Die Umrechnung der Microarraysignale in Präsenz-Absenz-Aussagen resultierte in einem Überblick über die Verteilung virulenzrelevanter Gene innerhalb der verschiedenen Arten der Oralstreptokokken und ermöglichte den Nachweis mehrerer Gene bedeutender Virulenzfaktoren, die ursächlich mit der Pathogenität der analysierten Oralstreptokokkenisolate zusammenhängen können. Die im Rahmen dieser Arbeit identifizierten gruppen- und speziesspezifischen Nukleinsäuresonden liefern zudem initiale Daten für die Entwicklung praxistauglicher hybridisierungsbasierter Diagnosemethoden.The term oral streptococci describes twelve species of the genus Streptococcus belonging to the natural microbial flora of the human oral cavity. Injuries of the oral mucous membranes and tissues allow the oral streptococci to enter the bloodstream and other areas of the human body, where they are able to develop a significant pathogenic potential. The bacterial factors that are responsible for the ability of the various oral streptococci species to colonize medical implants and tissue structures but also persist in the bloodstream are largely unknown. The aim of this study was the development of an interspecies DNA-Microarray system for the analysis of clinical oral streptococci isolates in relation to occurrence and distribution of known oral streptococcal virulence factors and homologous virulence mechanisms of obligate pathogenic streptococci species. A collection of 45 clinical oral streptococci isolates was analyzed using the developed microarray system. Clusteranalysis of normalized signals proved the applicability of the microarray as a method for bacterial species typing and allowed a deeper insight into the phylogenetic relationships within the oral streptococci. The conversion of microarray signals into presence-absence-data resulted in an overview of the distribution of virulence related genes within the different oral streptococci species and allowed the detection of several genes coding for important virulence factors that are a possible explanation for the pathogenic potential of oral streptococci. Furthermore, the identified group- and speciesspecific nucleic acid probes provide initial data for the development of hybridisation based diagnostic methods

Trigger for group A streptococcal M1T1 invasive disease

The globally disseminated Streptococcus pyogenes M1T1 clone causes a number of highly invasive human diseases. The transition from local to systemic infection occurs by an unknown mechanism; however invasive M1T1 clinical isolates are known to express significantly less cysteine protease SpeB than M1T1 isolates from local infections. Here, we show that in comparison to the M1T1 strain 5448, the isogenic mutant ΔspeB accumulated 75‐fold more human plasmin activity on the bacterial surface following incubation in human plasma. Human plasminogen was an absolute requirement for M1T1 strain 5448 virulence following subcutaneous (s.c.) infection of humanized plasminogen transgenic mice. S. pyogenes M1T1 isolates from the blood of infected humanized plasminogen transgenic mice expressed reduced levels of SpeB in comparison with the parental 5448 used as inoculum. We propose that the human plasminogen system plays a critical role in group A streptococcal M1T1 systemic disease initiation. SpeB is required for S. pyogenes M1T1 survival at the site of local infection, however, SpeB also disrupts the interaction of S. pyogenes M1T1 with the human plasminogen activation system. Loss of SpeB activity in a subpopulation of S. pyogenes M1T1 at the site of infection results in accumulation of surface plasmin activity thus triggering systemic spread.—Cole, J. N., McArthur, J. D., McKay, F. C., Sanderson‐Smith, M. L., Cork, A. J., Ranson, M., Rohde, M., Itzek, A., Sun, H., Ginsburg, D., Kotb, M., Nizet, V., Chhatwal, G. S., Walker, M. J. Trigger for group A streptococcal M1T1 invasive disease. FASEB J. 20, E1139–E1145 (2006)Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/154248/1/fsb2fj065804fje.pd

Contribution of Streptococcus anginosus to Infections Caused by Groups C and G Streptococci, Southern India

This neglected pathogen causes a large portion of these infections

Prothrombotic and Proinflammatory Activities of the β-Hemolytic Group B Streptococcal Pigment

A prominent feature of severe streptococcal infections is the profound inflammatory response that contributes to systemic toxicity. In sepsis the dysregulated host response involves both immunological and nonimmunological pathways. Here, we report a fatal case of an immunocompetent healthy female presenting with toxic shock and purpura fulminans caused by group B streptococcus (GBS; serotype III, CC19). The strain (LUMC16) was pigmented and hyperhemolytic. Stimulation of human primary cells with hyperhemolytic LUMC16 and STSS/NF-HH strains and pigment toxin resulted in a release of proinflammatory mediators, including tumor necrosis factor, interleukin (IL)-1β, and IL-6. In addition, LUMC16 induced blood clotting and showed factor XII activity on its surface, which was linked to the presence of the pigment. The expression of pigment was not linked to a mutation within the CovR/S region. In conclusion, our study shows that the hemolytic lipid toxin contributes to the ability of GBS to cause systemic hyperinflammation and interferes with the coagulation system

Differential Contributions of the Complement Anaphylotoxin Receptors C5aR1 and C5aR2 to the Early Innate Immune Response against Staphylococcus aureus Infection

The complement anaphylatoxin C5a contributes to host defense against Staphylococcus aureus. In this study, we investigated the functional role of the two known C5a receptors, C5aR1 and C5aR2, in the host response to S. aureus. We found that C5aR1−/− mice exhibited greater susceptibility to S. aureus bloodstream infection than wild type and C5aR2−/− mice, as demonstrated by the significantly higher bacterial loads in the kidneys and heart at 24 h of infection, and by the higher levels of inflammatory IL-6 in serum. Histological and immunohistochemistry investigation of infected kidneys at 24 h after bacterial inoculation revealed a discrete infiltration of neutrophils in wild type mice but already well-developed abscesses consisting of bacterial clusters surrounded by a large number of neutrophils in both C5aR1−/− and C5aR2−/− mice. Furthermore, blood neutrophils from C5aR1−/− mice were less efficient than those from wild type or C5aR2−/− mice at killing S. aureus. The requirement of C5aR1 for efficient killing of S. aureus was also demonstrated in human blood after disrupting C5a-C5aR1 signaling using specific inhibitors. These results demonstrated a role for C5aR1 in S. aureus clearance as well as a role for both C5aR1 and C5aR2 in the orchestration of the inflammatory response during infection

Detection of Streptococcus pyogenes virulence genes in Streptococcus dysgalactiae subsp. equisimilis from Vellore, India.

Streptococcus dysgalactiae subsp. equisimilis (SDSE), belonging to the group C and G streptococci, are human pathogens reported to cause clinical manifestations similar to infections caused by Streptococcus pyogenes. To scrutinize the distribution of gene coding for S. pyogenes virulence factors in SDSE, 255 isolates were collected from humans infected with SDSE in Vellore, a region in southern India, with high incidence of SDSE infections. Initial evaluation indicated SDSE isolates comprising of 82.35% group G and 17.64% group C. A multiplex PCR system was used to detect 21 gene encoding virulence-associated factors of S. pyogenes, like superantigens, DNases, proteinases, and other immune modulatory toxins. As validated by DNA sequencing of the PCR products, sequences homologous to speC, speG, speH, speI, speL, ssa and smeZ of the family of superantigen coding genes and for DNases like sdaD and sdc were detected in the SDSE collection. Furthermore, there was high abundance (48.12% in group G and 86.6% in group C SDSE) of scpA, the gene coding for C5a peptidase in these isolates. Higher abundance of S. pyogenes virulence factor genes was observed in SDSE of Lancefield group C as compared to group G, even though the incidence rates in former were lower. This study not only substantiates detection of S. pyogenes virulence factor genes in whole genome sequenced SDSE but also makes significant contribution towards the understanding of SDSE and its increasing virulence potential

Catabolite Control Protein A Controls Hydrogen Peroxide Production and Cell Death in Streptococcus sanguinis▿

Streptococcus sanguinis is a commensal oral bacterium producing hydrogen peroxide (H2O2) that is dependent on pyruvate oxidase (Spx) activity. In addition to its well-known role in bacterial antagonism during interspecies competition, H2O2 causes cell death in about 10% of the S. sanguinis population. As a consequence of H2O2-induced cell death, largely intact chromosomal DNA is released into the environment. This extracellular DNA (eDNA) contributes to the self-aggregation phenotype under aerobic conditions. To further investigate the regulation of spx gene expression, we assessed the role of catabolite control protein A (CcpA) in spx expression control. We report here that CcpA represses spx expression. An isogenic ΔccpA mutant showed elevated spx expression, increased Spx abundance, and H2O2 production, whereas the wild type did not respond with altered spx expression in the presence of glucose and other carbohydrates. Since H2O2 is directly involved in the release of eDNA and bacterial cell death, the presented data suggest that CcpA is a central control element in this important developmental process in S. sanguinis

Epidemiological and Clinical Features of <i>Streptococcus dysgalactiae</i> ssp. <i>equisimilis stG62647</i> and Other <i>emm</i> Types in Germany

(1) Background: Streptococcus dysgalactiae subspecies equisimilis (SDSE) is an important β-hemolytic pathogen historically described as mainly affecting animals. Studies epidemiologically assessing the pathogenicity in the human population in Germany are rare. (2) Methods: the present study combines national surveillance data from 2010 to 2022 with a single-center clinical study conducted from 2016 to 2022, focusing on emm type, Lancefield antigen, antimicrobial resistance, patient characteristics, disease severity, and clinical infection markers. (3) Results: The nationwide reported invasive SDSE infections suggest an increasing infection burden for the German population. One particular emm type, stG62647, increased over the study period, being the dominant type in both study cohorts, suggesting a mutation-driven outbreak of a virulent clone. The patient data show that men were more affected than women, although in the single-center cohort, this trend was reversed for patients with stG62647 SDSE. Men affected by stG62647 developed predominantly fascial infections, whereas women suffering from superficial and fascial non-stG62647 SDSE infections were significantly younger than other patients. Increasing age was a general risk factor for invasive SDSE infections. (4) Conclusions: further studies are needed to further elucidate the raised questions regarding outbreak origin, underlying molecular mechanisms as well as sex-dependent pathogen adaptation