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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 -
Revista Argentina de Microbiologia 2022The aim of this review is to present an update on the susceptibility of viridans group streptococci (VGS) to β-lactam antimicrobials, with emphasis on the Argentinean... (Review)
Review
The aim of this review is to present an update on the susceptibility of viridans group streptococci (VGS) to β-lactam antimicrobials, with emphasis on the Argentinean scenario. VGS are a heterogeneous group including five groups of species, each one exhibiting peculiar susceptibility patterns to penicillin (PEN). Species of the Streptococcus mitis group are frequently nonsusceptible to PEN. PEN resistance is associated with changes in PEN-binding proteins. In Argentina, one to two thirds of VGS are nonsusceptible to PEN. Third generation cephalosporins and carbapenems are currently more effective in vitro than PEN against VGS. Mortality was associated to nonsusceptibility to PEN in at least two studies involving patients with bacteremia caused by VGS. Treatment of endocarditis due to VGS should be adjusted/to the PEN susceptibility of the isolates. Vancomycin may be an alternative choice for treating endocarditis caused by PEN-resistant isolates (MIC≥4μg/ml).
Topics: Humans; Microbial Sensitivity Tests; Streptococcal Infections; Viridans Streptococci; Penicillins; Monobactams; beta-Lactams; Anti-Bacterial Agents; Endocarditis
PubMed: 36266147
DOI: 10.1016/j.ram.2022.06.004 -
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 -
Microbiology and Immunology Jun 2022Secondary bacterial infection following influenza type A virus (IAV) infection is a major cause of morbidity and mortality during influenza epidemics. Streptococcus... (Review)
Review
Secondary bacterial infection following influenza type A virus (IAV) infection is a major cause of morbidity and mortality during influenza epidemics. Streptococcus pneumoniae has been identified as a predominant pathogen in secondary pneumonia cases that develop following influenza. Although IAV has been shown to enhance susceptibility to the secondary bacterial infection, the underlying mechanism of the viral-bacterial synergy leading to disease progression is complex and remains elusive. In this review, cooperative interactions of viruses and streptococci during co- or secondary infection with IAV are described. IAV infects the upper respiratory tract, therefore, streptococci that inhabit or infect the respiratory tract are of special interest. As many excellent reviews on the co-infection of IAV and S. pneumoniae have already been published, this review is intended to describe the unique interactions between other streptococci and IAV. Both streptococcal and IAV infections modulate the host epithelial barrier of the respiratory tract in various ways. IAV infection directly disrupts epithelial barriers, though at the same time the virus modifies the properties of infected cells to enhance streptococcal adherence and invasion. Mitis group streptococci produce neuraminidases, which promote IAV infection in a unique manner. The studies reviewed here have revealed intriguing mechanisms underlying secondary streptococcal infection following influenza.
Topics: Coinfection; Humans; Influenza A virus; Influenza, Human; Orthomyxoviridae Infections; Streptococcal Infections; Streptococcus pneumoniae
PubMed: 35088451
DOI: 10.1111/1348-0421.12965 -
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 -
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 -
Scientific Reports Jan 2022Descriptions of the small intestinal microbiota are deficient and conflicting. We aimed to get a reliable description of the jejunal bacterial microbiota by...
Descriptions of the small intestinal microbiota are deficient and conflicting. We aimed to get a reliable description of the jejunal bacterial microbiota by investigating samples from two separate jejunal segments collected from the luminal mucosa during surgery. Sixty patients with morbid obesity selected for elective gastric bypass surgery were included in this survey. Samples collected by rubbing a swab against the mucosa of proximal and mid jejunal segments were characterized both quantitatively and qualitatively using a combination of microbial culture, a universal quantitative PCR and 16S deep sequencing. Within the inherent limitations of partial 16S sequencing, bacteria were assigned to the species level. By microbial culture, 53 patients (88.3%) had an estimated bacterial density of < 1600 cfu/ml in both segments whereof 31 (51.7%) were culture negative in both segments corresponding to a bacterial density below 160 cfu/ml. By quantitative PCR, 46 patients (76.7%) had less than 10 bacterial genomes/ml in both segments. The most abundant and frequently identified species by 16S deep sequencing were associated with the oral cavity, most often from the Streptococcus mitis group, the Streptococcus sanguinis group, Granulicatella adiacens/para-adiacens, the Schaalia odontolytica complex and Gemella haemolysans/taiwanensis. In general, few bacterial species were identified per sample and there was a low consistency both between the two investigated segments in each patient and between patients. The jejunal mucosa of fasting obese patients contains relatively few microorganisms and a core microbiota could not be established. The identified microbes are likely representatives of a transient microbiota and there is a high degree of overlap between the most frequently identified species in the jejunum and the recently described ileum core microbiota.
Topics: Adult; Aged; Bacteria; DNA, Bacterial; Female; Gastric Bypass; Gastrointestinal Microbiome; High-Throughput Nucleotide Sequencing; Humans; Intestinal Mucosa; Jejunum; Male; Middle Aged; Obesity, Morbid; Real-Time Polymerase Chain Reaction; Ribotyping; Young Adult
PubMed: 35102222
DOI: 10.1038/s41598-022-05723-9 -
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 -
Journal of Oral Microbiology 2022Human microbiomes assemble in an ordered, reproducible manner yet there is limited information about early colonisation and development of bacterial communities that...
BACKGROUND
Human microbiomes assemble in an ordered, reproducible manner yet there is limited information about early colonisation and development of bacterial communities that constitute the oral microbiome.
AIM
The aim of this study was to determine the effect of exposure to breastmilk on assembly of the infant oral microbiome during the first 20 months of life.
METHODS
The oral microbiomes of 39 infants, 13 who were never breastfed and 26 who were breastfed for more than 10 months, from the longitudinal VicGeneration birth cohort study, were determined at four ages. In total, 519 bacterial taxa were identified and quantified in saliva by sequencing the V4 region of the bacterial genes.
RESULTS
There were significant differences in the development of the oral microbiomes of never breastfed and breastfed infants. Bacterial diversity was significantly higher in never breastfed infants at 2 months, due largely to an increased abundance of and species from the phylum compared with breastfed infants.
CONCLUSION
These differences likely reflect breastmilk playing a prebiotic role in selection of early-colonising, health-associated oral bacteria, such as the group. The microbiomes of both groups became more heterogenous following the introduction of solid foods.
PubMed: 35832839
DOI: 10.1080/20002297.2022.2096287 -
Frontiers in Microbiology 2022Two-component signal transduction (TCS) systems are important regulatory pathways in streptococci. A typical TCS encodes a membrane-anchored sensor kinase (SK) and a... (Review)
Review
Two-component signal transduction (TCS) systems are important regulatory pathways in streptococci. A typical TCS encodes a membrane-anchored sensor kinase (SK) and a cytoplasmic response regulator (RR). Approximately, 20 different types of TCSs are encoded by various streptococci. Among them, two TCSs, in particular BlpRH and ComDE, are required for bacteriocins production and competence development. The SK component of these two TCSs is highly similar and belongs to the protein kinase-10 (HPK-10) subfamily. While these two TCSs are present in streptococci, no systematic studies have been done to differentiate between these two TCSs, and the existence of these pathways in several species of the genus Streptococcus is also unknown. The lack of information about these pathways misguided researchers for decades into believing that the BlpRH system is a ComDE system. Here, we have attempted to distinguish between the BlpRH and ComDE systems based on the location of the chromosome, genomic arrangement, and conserved residues. Using the SyntTax and NCBI databases, we investigated the presence of both TCS systems in the genome of several streptococcal species. We noticed that the NCBI database did not have proper annotations for these pathways in several species, and many of them were wrongly annotated, such as CitS or DpiB instead of BlpH. Nevertheless, our critical analyses led us to classify streptococci into two groups: class A (only the BlpRH system) and class B (both the BlpRH and ComDE systems). Most of the streptococcal groups, including bovis, pyogenic, mutans, salivarius, and suis, encode only the BlpRH system. In contrast, only in the mitis and anginosus groups were both the TCS systems present. The focus of this review is to identify and differentiate between the BlpRH and ComDE systems, and discuss these two pathways in various streptococci.
PubMed: 36353461
DOI: 10.3389/fmicb.2022.960994