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European Journal of Clinical... Dec 2020The Mitis group of streptococci includes an important human pathogen, Streptococcus pneumoniae (pneumococcus) and about 20 other related species with much lower... (Review)
Review
The Mitis group of streptococci includes an important human pathogen, Streptococcus pneumoniae (pneumococcus) and about 20 other related species with much lower pathogenicity. In clinical practice, some representatives of these species, especially Streptococcus pseudopneumoniae and Streptococcus mitis, are sometimes mistaken for S. pneumoniae based on the results of classical microbiological methods, such as optochin susceptibility and bile solubility. Several various molecular approaches that address the issue of correct identification of pneumococci and other Mitis streptococci have been proposed and are discussed in this review, including PCR- and gene sequencing-based tests as well as new developments in the genomic field that represents an important advance in our understanding of relationships within the Mitis group.
Topics: Automation; Humans; Multilocus Sequence Typing; Phenotype; Polymerase Chain Reaction; Streptococcus mitis; Streptococcus pneumoniae; Whole Genome Sequencing
PubMed: 32710352
DOI: 10.1007/s10096-020-03991-9 -
BMJ Case Reports Jan 2021We report a case of a 42-year-old man who presented with acute epigastric and retrosternal chest pain and exertional dyspnoea, and was subsequently diagnosed with...
We report a case of a 42-year-old man who presented with acute epigastric and retrosternal chest pain and exertional dyspnoea, and was subsequently diagnosed with polyserositis secondary to post- infection. A CT scan showed a large pericardial effusion requiring pericardiocentesis, small bilateral pleural effusions and small amount of ascites. Several serological tests were done, which were all found to be normal. Pericardial and pleural fluid aspirates revealed an exudate. Culture of the pleural fluid yielded growth of and this was deemed the cause of the polyserositis, which is rare. The patient made a spontaneous recovery. He was started on colchicine by the cardiologists to help prevent pericardial fluid recurrence and this was continued for 3 months. A dental review confirmed the presence of dental caries, the possible source of infection. On follow-up, the patient remained well with no further relapses.
Topics: Adult; Anti-Inflammatory Agents; Ascites; Colchicine; Humans; Male; Pericardial Effusion; Pericardiocentesis; Pleural Effusion; Serositis; Streptococcal Infections; Streptococcus mitis; Tomography, X-Ray Computed
PubMed: 33472801
DOI: 10.1136/bcr-2020-236704 -
MSphere Feb 2021Lipoteichoic acid (LTA) is a Gram-positive bacterial cell surface polymer that participates in host-microbe interactions. It was previously reported that the major human...
Lipoteichoic acid (LTA) is a Gram-positive bacterial cell surface polymer that participates in host-microbe interactions. It was previously reported that the major human pathogen and the closely related oral commensals and produce type IV LTAs. Herein, using liquid chromatography/mass spectrometry-based lipidomic analysis, we found that in addition to type IV LTA biosynthetic precursors, , , and also produce glycerophosphate (Gro-P)-linked dihexosyl (DH)-diacylglycerol (DAG), which is a biosynthetic precursor of type I LTA. and mutants produce DHDAG but lack (Gro-P)-DHDAG, indicating that the Gro-P moiety is derived from phosphatidylglycerol (PG), whose biosynthesis requires these genes. , but not or , encodes an ortholog of the PG-dependent type I LTA synthase, By heterologous expression analyses, we confirmed that confers poly(Gro-P) synthesis in both and and that can rescue the growth defect of an mutant. However, we do not detect a poly(Gro-P) polymer in using an anti-type I LTA antibody. Moreover, Gro-P-linked DHDAG is still synthesized by an mutant, demonstrating that LtaS does not catalyze Gro-P transfer to DHDAG. Finally, an mutant has increased sensitivity to human serum, demonstrating that confers a beneficial but currently undefined function in Overall, our results demonstrate that , , and produce a Gro-P-linked glycolipid via a PG-dependent, -independent mechanism. The cell wall is a critical structural component of bacterial cells that confers important physiological functions. For pathogens, it is a site of host-pathogen interactions. In this work, we analyze the glycolipids synthesized by the mitis group streptococcal species, , , and We find that all produce the glycolipid, glycerophosphate (Gro-P)-linked dihexosyl (DH)-diacylglycerol (DAG), which is a precursor for the cell wall polymer type I lipoteichoic acid in other bacteria. We investigate whether the known enzyme for type I LTA synthesis, LtaS, plays a role in synthesizing this molecule in Our results indicate that a novel mechanism is responsible. Our results are significant because they identify a novel feature of , , and glycolipid biology.
Topics: Glycerophosphates; Glycolipids; Lipopolysaccharides; Phosphatidylglycerols; Streptococcus mitis; Streptococcus oralis; Streptococcus pneumoniae; Teichoic Acids
PubMed: 33627509
DOI: 10.1128/mSphere.01099-20 -
Journal of Infection in Developing... May 2021Streptococcus pneumoniae can be responsible for severe human infections. Optochin resistance has been a potential cause of misidentification of pneumococcus and other...
INTRODUCTION
Streptococcus pneumoniae can be responsible for severe human infections. Optochin resistance has been a potential cause of misidentification of pneumococcus and other members of the mitis group. Hence, rapid and easy optochin resistant (Optr) S. pneumoniae identification is essential.
METHODOLOGY
Atypical pneumococci were characterized using optochin susceptibility, bile solubility based on spectrophotometric reading, serotyping, pulsed field gel electrophoresis (PFGE), 16S rRNA sequencing and PCR-based assays targeting pneumococcal genes lytA, ply, pspA, cpsA, Spn9802 and Spn9828.
RESULTS
Optical density values for the bile solubility test suggest the identification of four Optr S. pneumoniae and one Streptococcus pseudopneumoniae. All Optr pneumococci harbored cpsA, lytA, ply, Spn9802, Spn9828 and pspA genes. Only ply, spn9802 and Spn9828 genes were detected in S. pseudopneumoniae. The 16S rRNA sequencing differentiates between these two species. Optr S. pneumoniae strains belonged to different genotypes and serotypes (14, 19A, 3 and 9V). Three Optr S. pneumoniae isolates were typed as pspA family 2, while one belonged to pspA family 1. Sequencing of the atpA and atpC gene of the Optr variants revealed three mutations in the ATPase a-subunit (L99I, M23V and V52I) and one mutation in ATPase c-subunit (V48I).
CONCLUSIONS
Our data indicate that bile OD-values provides an accurate, fast and easy method to discriminate between Optr S. pneumoniae and other Streptococcus mitis group. Moreover molecular techniques, confirming the bile test, can be used in order to prevent these atypical pneumococci and alert clinical microbiologists of the presence of these strains in the community.
Topics: Drug Resistance, Bacterial; Genes, Bacterial; Genotype; Humans; Microbial Sensitivity Tests; Molecular Diagnostic Techniques; Quinine; RNA, Ribosomal, 16S; Streptococcal Infections; Streptococcus; Streptococcus pneumoniae; Tunisia
PubMed: 34106891
DOI: 10.3855/jidc.13106 -
Frontiers in Cellular and Infection... 2019The mitis group of streptococci comprises species that are common colonizers of the naso-oral-pharyngeal tract of humans. and are close relatives and share ~60-80% of... (Review)
Review
The mitis group of streptococci comprises species that are common colonizers of the naso-oral-pharyngeal tract of humans. and are close relatives and share ~60-80% of orthologous genes, but still present striking differences in pathogenic potential toward the human host. has long been recognized as a reservoir of antibiotic resistance genes for , as well as a source for capsule polysaccharide variation, leading to resistance and vaccine escape. Both species share the ability to become naturally competent, and in this context, competence-associated killing mechanisms such as fratricide are thought to play an important role in interspecies gene exchange. Here, we explore the general mechanism of natural genetic transformation in the two species and touch upon the fundamental clinical and evolutionary implications of sharing similar competence, fratricide mechanisms, and a large fraction of their genomic DNA.
Topics: DNA Transformation Competence; Gene Transfer, Horizontal; Genome, Bacterial; Streptococcus mitis; Streptococcus pneumoniae; Transformation, Bacterial
PubMed: 31001492
DOI: 10.3389/fcimb.2019.00094 -
Microbiology Spectrum Jun 2023Streptococcus mitis is a normal member of the human oral microbiota and a leading opportunistic pathogen causing infective endocarditis (IE). Despite the complex...
Streptococcus mitis is a normal member of the human oral microbiota and a leading opportunistic pathogen causing infective endocarditis (IE). Despite the complex interactions between S. mitis and the human host, understanding of S. mitis physiology and its mechanisms of adaptation to host-associated environments is inadequate, especially compared with other IE bacterial pathogens. This study reports the growth-promoting effects of human serum on S. mitis and other pathogenic streptococci, including S. oralis, S. pneumoniae, and S. agalactiae. Using transcriptomic analyses, we identified that, with the addition of human serum, S. mitis downregulates uptake systems for metal ions and sugars, fatty acid biosynthetic genes, and genes involved in stress response and other processes related with growth and replication. S. mitis upregulates uptake systems for amino acids and short peptides in response to human serum. Zinc availability and environmental signals sensed by the induced short peptide binding proteins were not sufficient to confer the growth-promoting effects. More investigation is required to establish the mechanism for growth promotion. Overall, our study contributes to the fundamental understanding of S. mitis physiology under host-associated conditions. S. mitis is exposed to human serum components during commensalism in the human mouth and bloodstream pathogenesis. However, the physiological effects of serum components on this bacterium remain unclear. Using transcriptomic analyses, S. mitis biological processes that respond to the presence of human serum were revealed, improving the fundamental understanding of S. mitis physiology in human host conditions.
Topics: Humans; Streptococcus mitis; Transcriptome; Streptococcus; Streptococcus pneumoniae; Endocarditis; Biological Phenomena; Dietary Supplements
PubMed: 37014220
DOI: 10.1128/spectrum.05129-22 -
Virulence 2015Streptococcus tigurinus is a novel species of viridans streptococci, shown to cause severe invasive infections such as infective endocarditis, spondylodiscitis and... (Review)
Review
Streptococcus tigurinus is a novel species of viridans streptococci, shown to cause severe invasive infections such as infective endocarditis, spondylodiscitis and meningitis. S. tigurinus belongs to the Streptococcus mitis group and is most closely related to Streptococcus mitis, Streptococcus oralis, Streptococcus pneumoniae, Streptococcus pseudopneumoniae and Streptococcus infantis. The presence of S. tigurinus in the human oral cavity has been documented, including in patients with periodontal disease. This review addresses the available scientific knowledge on S. tigurinus and its association with closely related streptococci, and discusses its putative involvement in common oral infections. While there is as yet no strong evidence on the involvement of S. tigurinus with oral infections, its presence in the oral cavity and its association with endocarditis warrants special attention for a link between oral and systemic infection.
Topics: DNA, Bacterial; Endocarditis, Bacterial; Humans; Microbiota; Mouth; Periodontal Diseases; Periodontitis; RNA, Ribosomal, 16S; Sequence Analysis, DNA; Streptococcal Infections; Streptococcus; Streptococcus mitis
PubMed: 25483862
DOI: 10.4161/21505594.2014.970472 -
Genome Biology and Evolution Apr 2019Taxonomic and phylogenetic relationships of Streptococcus mitis and Streptococcus oralis have been difficult to establish biochemically and genetically. We used...
Taxonomic and phylogenetic relationships of Streptococcus mitis and Streptococcus oralis have been difficult to establish biochemically and genetically. We used core-genome analyses of S. mitis and S. oralis, as well as the closely related species Streptococcus pneumoniae and Streptococcus parasanguinis, to clarify the phylogenetic relationships between S. mitis and S. oralis, as well as within subclades of S. oralis. All S. mitis (n = 67), S. oralis (n = 89), S. parasanguinis (n = 27), and 27 S. pneumoniae genome assemblies were downloaded from NCBI and reannotated. All genes were delineated into homologous clusters and maximum-likelihood phylogenies built from putatively nonrecombinant core gene sets. Population structure was determined using Bayesian genome clustering, and patristic distance was calculated between populations. Population-specific gene content was assessed using a phylogenetic-based genome-wide association approach. Streptococcus mitis and S. oralis formed distinct clades, but species mixing suggests taxonomic misassignment. Patristic distance between populations suggests that S. oralis subsp. dentisani is a distinct species, whereas S. oralis subsp. tigurinus and subsp. oralis are supported as subspecies, and that S. mitis comprises two subspecies. None of the genes within the pan-genomes of S. mitis and S. oralis could be statistically correlated with either, and the dispensable genomes showed extensive variation among isolates. These are likely important factors contributing to established overlap in biochemical characteristics for these taxa. Based on core-genome analysis, the substructure of S. oralis and S. mitis should be redefined, and species assignments within S. oralis and S. mitis should be made based on whole-genome analysis to be robust to misassignment.
Topics: Genome, Bacterial; Phylogeny; RNA, Ribosomal, 16S; Streptococcus mitis; Streptococcus oralis
PubMed: 30847473
DOI: 10.1093/gbe/evz049 -
Pathogens (Basel, Switzerland) Sep 2023Oral microbiome disruptions in periodontitis are related to the chronic inflammatory reactions that could in turn lead to the development of multiple oral diseases. The...
Oral microbiome disruptions in periodontitis are related to the chronic inflammatory reactions that could in turn lead to the development of multiple oral diseases. The objective of the study was to assess the frequencies of , , and in oral benign lesions, oral potentially malignant disorders (OPMDs), and oral squamous cell carcinomas (OSCCs) and investigate the impact of these bacteria on the expression patterns of the selected (potential) target genes (//, /, and ). After sample collection (25 benign lesions, 30 OPMDs, and 35 OSCCs) and DNA/RNA extraction, quantitative real-time polymerase chain reaction (qPCR) was performed to detect bacterial presence and assess relative gene expression levels in different lesion groups. was the most prevalent of the three analyzed bacteria, with the frequency being 60% in benign lesions, 87% in OPMDs ( = 0.024), and 77% in OSCC. The OPMD tissues in which was present exhibited a higher expression level of ( = 0.042). Significantly lower expression of was observed in OSCC tissues containing ( = 0.011). The obtained results indicate a substantial contribution of and in the pathogenesis of oral mucosal lesions, possibly via upregulation and downregulation.
PubMed: 37887710
DOI: 10.3390/pathogens12101194 -
Microbial Genomics Mar 2021Research into the lower urinary tract (LUT) microbiota has primarily focused on its relationship to LUT symptoms (LUTS), taking snapshots of these communities in... (Clinical Trial)
Clinical Trial
Research into the lower urinary tract (LUT) microbiota has primarily focused on its relationship to LUT symptoms (LUTS), taking snapshots of these communities in individuals with and without LUTS. While certain bacterial taxa have been associated with LUTS, or the lack thereof, the temporal dynamics of this community were largely unknown. Recently, we conducted a longitudinal study and found that vaginal intercourse resulted in a shift in species richness and diversity within the LUT microbiota. This is particularly relevant as frequent vaginal intercourse is a major risk factor for urinary tract infection (UTI) in premenopausal women (Aydin 2015;26:795-804). To further investigate the relationship between vaginal intercourse and LUT microbiota, here we present the results of a 3 week study in which daily urogenital specimens were collected from a female participant and her male sexual partner. Consistent with our previous findings, the LUT microbiota changed after vaginal intercourse, most notably a high abundance of was observed post-coitus. We isolated and sequenced from both sexual partners finding that: (i) the isolates from the female partner's urogenital tract were genomically similar throughout the duration of the study, and (ii) they were related to one isolate from the male partner's oral cavity collected at the end of the study, suggesting transmission between the two individuals. We hypothesize that blooms in after vaginal intercourse may play a role in coitus-related UTI. We found that a isolate, in contrast to a isolate displaced after vaginal intercourse, cannot inhibit the growth of uropathogenic . Thus, this bloom in may provide a window of opportunity for a uropathogen to colonize the LUT.
Topics: Adult; Female; Genome, Bacterial; Genomics; Humans; Longitudinal Studies; Male; Microbiota; Mouth; Sexual Behavior; Sexual Partners; Streptococcus mitis; Urinary Tract Infections; Vagina
PubMed: 33629947
DOI: 10.1099/mgen.0.000535