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At least 19 recordsLinked to original sources
PubMed1995

Relatedness among penicillin-binding protein 2b genes of Streptococcus mitis, Streptococcus oralis, and Streptococcus pneumoniae.

Penicillin-binding protein (PBP) 2b similarities among Streptococcus mitis, S. oralis, and S. pneumoniae using DNA fingerprinting and sequencing were investigated. The polymerase chain reaction (PCR) was performed on 41 penicillin-susceptible and -resistant clinical isolates of S. mitis and S. oralis using the susceptible S. pneumoniae R6 PBP 2b primers. PCR products were then analyzed using Hinf I and Sty I restriction enzymes. Of 41 S. mitis/S. oralis isolates studied 15 strains produced a PCR product of a similar size to that of S. pneumoniae R6. On fingerprinting these 15 strains, 11 different patterns were seen using Sty I restriction enzyme and 12 different patterns with Hinf I. The PBP 2b genes of the S. mitis and S. oralis isolates studied were found to be very heterogenous. The PBP 2b genes of two S. mitis isolates, MICs 0.5 and 2 micrograms/ml, were sequenced. These PBP 2b genes were found to possess a mosaic structure when compared to those of other S. pneumoniae and viridans streptococcal species. Analysis of these mosaic blocks indicates that both S. mitis strains contain areas that originated from S. pneumoniae as well as regions of unknown origin. PBP 2b sequence comparisons of a susceptible S. oralis with reported sequences of S. pneumoniae R6 and S. mitis NCTC 10712 revealed what appears at this stage to be nucleotide regions unique to S. oralis. A penicillin-resistant S. oralis strain contained a pneumococcal region of 272 bp that was flanked by S. oralis sequences. These specific S. oralis regions have been located in PBP 2b genes of penicillin-resistant S. oralis and S. pneumoniae isolates described from Europe and South Africa.

Bacterial Proteins↗
PubMed1984

In-vivo dental plaque-forming ability and relative cariogenicity of the bacteria Streptococcus mitis and Streptococcus sanguis I and II in mono-infected gnotobiotic rats.

Sixteen strains of Streptococcus mitis, Streptococcus sanguis I and Strep. sanguis II were tested for cariogenic potential and in-vivo plaque-forming ability in a gnotobiotic WAG/RIJ rat test system. All strains produced far less fissure plaque in vivo than strains of Streptococcus milleri or Streptococcus mutans. There was less extracellular matrix around cells of Strep. mitis or Strep. sanguis than around Strep. mutans, in the fissures. Dense sheets of cells were observed only with Strep. mutans. Some localized colonization of exposed smooth surfaces occurred with most strains. Strep. mitis produced no caries in three tests, low-caries scores in two tests and high-caries scores in one test. A single strain of Strep. mitis produced a highly-cariogenic variant able to ferment raffinose. Strep. sanguis I induced low-levels of caries in 12 tests; one test of NCTC 7865 produced moderate levels of caries, and another test of 311 produced no caries. Strep. sanguis 311 was dextran-negative. Strep. sanguis II strains induced no caries in three tests, low caries scores in six tests and moderate levels of caries with Strep. sanguis 402. No strain of Strep. mitis or Strep. sanguis was able to induce smooth-surface lesions.

Animals↗
PubMed2006

Use of the housekeeping genes, gdh (zwf) and gki, in multilocus sequence typing to differentiate Streptococcus pneumoniae from Streptococcus mitis and Streptococcus oralis.

Polymerase chain reaction and sequencing of the housekeeping genes, gdh (zwf) and gki, based on the primers and alleles from multilocus sequence typing can be used to delineate and support the identity of clinical isolates of Streptococcus pneumoniae and differentiate from the closely related Streptococcus mitis and Streptococcus oralis.

Bacterial Typing Techniques↗
PubMed1986

Coordinate repression of arginine aminopeptidase and three enzymes of the arginine deiminase pathway in Streptococcus mitis.

Streptococcus mitis contains two arginine aminopeptidases (I and II) as an arginine-supplying system and the arginine deiminase pathway as an arginine-utilizing system. The levels of arginine aminopeptidase I and three enzymes of the arginine deiminase pathway were suppressed by glucose in an apparently coordinate manner. Enzyme II appeared to be constitutive.

Aminopeptidases↗
PubMed1991

Characterization of infectious crystalline keratitis caused by a human isolate of Streptococcus mitis.

Streptococcus mitis isolated from a human with infectious crystalline keratitis was injected intrastromally into corneas of adult New Zealand white rabbits that were treated with tetracycline hydrochloride, methylprednisolone acetate, or a combination of tetracycline and methylprednisolone. Animals were followed up for up to 44 days; untreated corneas and those treated with tetracycline developed no disease or "fluffy" stromal infiltrates with overlying epithelial defects representing an abscess. Corneas treated with the combination of tetracycline and corticosteroid usually developed crystalline stromal opacities that on histopathologic examination were shown to be intrastromal aggregates of cocci. Transmission electron microscopy of crystalline lesions within 10 days of infection revealed typical cocci intermixed with a fibrillar material having periodicity characteristic of fibrinogen or fibrin, and immunoperoxidase staining for fibrinogen was positive. By 1 month, electron microscopy revealed aggregates of degenerated bacteria that were surrounded by cellular processes of activated keratocytes. Our studies demonstrate a model for crystalline keratitis in which organisms are seen to reside within the stroma for up to 44 days without an inflammatory response. Periocular corticosteroids appear to be necessary to create this model. It is possible that the organisms are isolated from the host response by fibrin or by keratocytes.

Abscess↗
PubMed1995

Determination of 16S rRNA sequences of Streptococcus mitis and Streptococcus gordonii and phylogenetic relationships among members of the genus Streptococcus.

We determined the 16S rRNA sequences of the type strains of Streptococcus mitis and Streptococcus gordonii and calculated the phylogenetic distances between those organisms and other members of the genus Streptococcus. The viridans group streptococci were separated into five phylogenetic groups; we named these groups the anginosus group, the mitis group, the salivarius group, the bovis group, and the mutans group. S. mitis and S. gordonii clustered in the mitis group together with Streptococcus pneumoniae, Streptococcus oralis, Streptococcus sanguis, and Streptococcus parasanguis at levels of sequence homology of more than 96%. Within this group, S. mitis, S. oralis, and S. pneumoniae exhibited more than 99% sequence homology with each other, although the DNA-DNA similarity values for their total chromosome DNAs were less than 60%.

DNA, Bacterial↗
PubMed1984

Neuraminidase activity: a biochemical marker to distinguish Streptococcus mitis from Streptococcus sanguis.

Selected reference and freshly isolated strains of Streptococcus mitis (mitior) and Streptococcus sanguis were assayed for cell-associated neuraminidase activity by their ability to hydrolyze [3H-] sialyllactitol. A cell-associated neuraminidase was detected with S. mitis and S. sanguis serotype II (reclassified as S. mitis) but not with S. sanguis serotypes I and III. Neuraminidase activity of S. mitis correlated with this organism's inability to hydrolyze arginine, aesculin, and few, if any, sugars. The findings indicate that the presence of cell-associated neuraminidase activity is useful for the taxonomic classification of S. mitis.

Arginine↗
PubMed2004

Frequent and preferential infection of Treponema denticola, Streptococcus mitis, and Streptococcus anginosus in esophageal cancers.

Multiple cancers frequently occur in the upper digestive tract. One possible explanation is that specific bacterial infection stimulates the normal epithelium to initiate inflammation and/or promotes carcinogenesis. This study was undertaken to determine which bacterial species is predominantly associated with esophageal cancer. We examined the bacterial diversity in this type of cancer and in the saliva from healthy people by using a culture-independent molecular method. Here we report the preferential and frequent infection of the oral periodontopathic spirochete Treponema denticola (T. denticola), Streptococcus mitis (S. mitis), and Streptococus anginosus (S. anginosus) in esophageal cancer from different regions of the world, and we also describe the induction of inflammatory cytokines by infection of S. anginosus and S. mitis. Our present data suggest that these three bacteria could have significant roles in the carcinogenic process of many cases of esophageal cancer by causing inflammation and by promoting the carcinogenic process, and that eradication of these three bacteria may decrease the risk of recurrence.

Blotting, Northern↗
PubMed1998

Acquisition of five high-Mr penicillin-binding protein variants during transfer of high-level beta-lactam resistance from Streptococcus mitis to Streptococcus pneumoniae.

Penicillin-resistant isolates of Streptococcus pneumoniae generally contain mosaic genes encoding the low-affinity penicillin-binding proteins (PBPs) PBP2x, PBP2b, and PBP1a. We now present evidence that PBP2a and PBP1b also appear to be low-affinity variants and are encoded by distinct alleles in beta-lactam-resistant transformants of S. pneumoniae obtained with chromosomal donor DNA from a Streptococcus mitis isolate. Different lineages of beta-lactam-resistant pneumococcal transformants were analyzed, and transformants with low-affinity variants of all high-molecular-mass PBPs, PBP2x, -2a, -2b, -1a, and -1b, were isolated. The MICs of benzyl-penicillin, oxacillin, and cefotaxime for these transformants were up to 40, 100, and 50 microg/ml, respectively, close to the MICs for the S. mitis donor strain. Recruitment of low-affinity PBPs was accompanied by a decrease in cross-linked muropeptides as revealed by high-performance liquid chromatography of muramidase-digested cell walls, but no qualitative changes in muropeptide chemistry were detected. The growth rates of all transformants were identical to that of the parental S. pneumoniae strain. The results stress the potential for the acquisition by S. pneumoniae of high-level beta-lactam resistance by interspecies gene transfer.

Amino Acid Sequence↗
PubMed1999

Humoral immunity to commensal oral bacteria in human infants: salivary secretory immunoglobulin A antibodies reactive with Streptococcus mitis biovar 1, Streptococcus oralis, Streptococcus mutans, and Enterococcus faecalis during the first two years of life.

Secretory immunoglobulin A (SIgA) antibodies reactive with the pioneer oral streptococci Streptococcus mitis biovar 1 and Streptococcus oralis, the late oral colonizer Streptococcus mutans, and the pioneer enteric bacterium Enterococcus faecalis in saliva samples from 10 human infants from birth to age 2 years were analyzed. Low levels of salivary SIgA1 and SIgA2 antibodies reactive with whole cells of all four species were detected within the first month after birth, even though S. mutans and E. faecalis were not recovered from the mouths of the infants during the study period. Although there was a fivefold increase in the concentration of SIgA between birth and age 2 years, there were no differences between the concentrations of SIgA1 and SIgA2 antibodies reactive with the four species over this time period. When the concentrations of SIgA1 and SIgA2 antibodies reactive with all four species were normalized to the concentrations of SIgA1 and SIgA2 in saliva, SIgA1 and SIgA2 antibodies reactive with these bacteria showed a significant decrease from birth to 2 years of age. Adsorption of each infant's saliva with cells of one species produced a dramatic reduction of antibodies recognizing the other three species. Sequential adsorption of saliva samples removed all SIgA antibody to the bacteria, indicating that the SIgA antibodies were directed to antigens shared by all four species. The induction by the host of a limited immune response to common antigens that are likely not involved in adherence may be among the mechanisms that commensal streptococci employ to persist in the oral cavity.

Antibodies, Bacterial↗
PubMed1997

[Mitral endocarditis secondary to Streptococcus mitis bacteremic pneumonia].

Streptococcus viridans usually are an etiologic agent in odontogenic infection and endocarditis and only in some cases have been acknowledged as a respiratory pathogens. We present two cases of Streptococcus mitis bacteremic pneumonia with secondary mitral endocarditis in two patients that were been admitted by a respiratory infection (pneumonia), and later diagnosticated of mitral endocarditis. We dismiss the fisiopathogenic possibility of pneumonia with secondary pulmonary septic embolisms. With this description we help to prove the S. mitis respiratory system pathogenicity and show the known risk of endocarditis in any case of Streptococcus viridans bacteremic infection.

Bacteremia↗
PubMed1978

Isoelectric focusing studies on the beta-fructofuranosidases and alpha-glucosidases of Streptococcus mitis.

Extracts of Streptococcus mitis ATCC 903 were analysed for beta-fructofuranosidase and alpha-glucosidase activities by isoelectric focusing in thin-layer polyacrylamide gels combined with zymogram procedures. Three bands of activity were visualized in the gels after incubation with sucrose (pI 4.05, 4.25 and 4.85) and three other bands after incubation with p-nitrophenyl alpha-D-glucopyranoside (pI 3.90, 4.45 and 4.65). The enzymes responsible for the reaction with sucrose were identified as beta-fructofuranosidases (EC 3.2.1.26) for the following reasons: identical enzyme bands were visualized in the gels after incubation with raffinose; no enzyme bands appeared in the gel after incubation with the alpha-glucosides maltose, turanose, trehalose and melezitose; and the soluble fraction hydrolysed sucrose to equimolar amounts of glucose and fructose.

Glucosidases↗
PubMed1983

Protoplast formation and localization of enzymes in Streptococcus mitis.

Cells of Streptococcus mitis ATCC 903 were converted to stable protoplasts by the cell wall-degrading M-1 enzyme of the mutanolysin complex isolated from Streptomyces globisporus. Over 90% of total glucokinase (EC 2.7.1.2), aminopeptidase (EC 3.4.11.1), and dextranglucosidase (EC 3.2.1.70) was recovered in the cytoplasmic fraction, whereas over 20% of total invertase (beta-fructofuranosidase: EC 3.2.1.26) was released during protoplast formation. ATPase (EC 3.6.1.3). chymotrypsin-like protease (EC 3.4.21.1), arginine aminopeptidase (EC 3.4.11.6), and lactate dehydrogenase (EC 1.1.1.27) were detected in Triton X-100 extracts of the cytoplasmic membrane fraction by crossed immunoelectrophoresis in combination with enzyme-staining procedures. By these methods, NADH dehydrogenase (EC 1.6.99.3), aminopeptidase, and lactate dehydrogenase were detected in the cytoplasmic fraction. Aminopeptidases in the cytoplasmic fraction differed from this activity in the membrane fractions in electrophoretic mobility and substrate specificity.

Cell Membrane↗