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PubMed2003

[Streptococcus bovis infectious endocarditis: clinical and epidemiological characteristics].

This paper shows our experience concerning the study of Streptococcus bovis infectious endocarditis (EI): 47 patients, with no prior history of IV drug abuse (NTD), who suffered EI caused by Streptococcus bovis were excerpted from a case record of 1053 cases with diagnosis of EI defined in accordance with Duke's Hospital criteria. For each patient we considered age, sex, complications, echocardiographic findings, antibiotic therapy, eventual heart-surgery and final outcome of the disease. We then compared the parameters of our patients, with the ones of 216 NTD patients suffering non Streptococcus bovis EI, selected according to age correspondence and concomitant onset of the disease. The characteristics of Streptococcus bovis EI are analogous to the ones of EIs caused by other micro-organisms in NTD patients, except for a non statistically significant trend of higher frequency in old age and in males. Concerning possible predisposing conditions, we considered the association extensively described in the literature between Streptococcus bovis EI and gastroenteric pathology (above all colon neoplasms): this association was not frequently observed in our study because appropriate instrumental investigations of the digestive tract were carried out only in a minority of patients.

Adult↗
PubMed2004

[Macrolide-resistant Streptococcus pneumoniae in the pediatric population in Beijing].

OBJECTIVE: To analyze the mechanisms of macrolide resistance in Streptococcus pneumoniae from children in Beijing. METHODS: The MICs of penicillin and erythromycin were determined by the E-test methods for 200 Streptococcus pneumoniae isolates collected from 2002 to 2003 at Beijing Children's Hospital. MICs of azithrhomycin, clarithromycin, acetylspiramycin and clindamycin for 147 erythromycin-resistant isolates were detected by the agar dilution methods. For phenotyping, macrolide resistance induction tests were used in erythromycin-resistant isolates. PCR was used to determine the presence of the erythromycin-resistant genes. RESULTS: Of 200 Streptococcus pneumoniae isolates, 89.5% were resistant to erythromycin. In 147 erythromycin-resistant isolates, resistance rates were as follows: azithromycin, 100%; clarithromycin, 100%; acetylspiramycin, 95.2%; and clindamycin, 95.9%. The most common macrolide resistance phenotype was the cMIS phenotype (95.9%), 1.4% had the iMLS phenotype and 2.7% the M phenotype. Erythromycin-resistant isolates were characterized for the underlying resistance genotype, with 79.6% having the ermB genotypes, 17.7% having both ermB and mefA, 2.7% having the mefA, and none having neither ermB nor mefA genotypes. CONCLUSIONS: The rates of carriage of macrolide-resistant Streptococcus pneumoniae by children were high in Beijing during 2002 - 2003. cMLS was the most prevalent phenotype among erythromycin-resistant Streptococcus pneumoniae isolates, and ribosomal modification (ermB gene coded) was the main resistance mechanism against macrolides in Beijing region.

Anti-Bacterial Agents↗
PubMed2005

Prevalence of the suilysin gene in Streptococcus suis strains isolated from diseased and healthy carrier pigs.

Knowledge of virulence factors of Streptococcus suis is limited. Several virulence factor candidates have been proposed, among them suilysin, which is responsible for a toxic effect on epithelial cells. The aim of this study was to detect the suilysin gene sequence in Streptococcus suis strains of various origin. In total 63 Streptococcus suis isolates were investigated. Forty four of them originated from tissues of streptococcosis affected animals. The remaining 19 strains were isolated from tonsils of healthy carrier pigs. Suilysin gene specific sequence was detected in 79% of the strains tested. In isolates obtained from pigs with signs of streptococcosis this gene sequence was recorded in 85% of cases. In Streptococcus suis strains isolated from healthy carrier pigs the suilysin gene was detected in 63% of the isolates. It seems that suilysin toxic activity is only one of the many steps involved in the pathogenesis of Streptococcus suis infection and that strain's virulence cannot be stated only on the basis of suilysin gene sequence presence.

Animals↗
PubMed2005

Development of myringosclerosis during acute otitis media caused by Streptococcus pneumoniae and non-typeable Haemophilus influenzae: a clinical otomicroscopical study using the rat model.

OBJECTIVE: The present study was performed in order to study development of myringosclerosis during acute otitis media caused by different bacteria in myringotomized and non-myringotomized ears. MATERIAL AND METHODS: A rat model of acute otitis media caused by Streptococcus pneumoniae type 3 and non-typeable Haemophilus influenzae was used. A sample consisted of 42 animals. Four days following middle ear inoculation, a myringotomy was performed in 10 animals from the Streptococcus pneumoniae group and 6 from the non-typeable Haemophilus influenzae group. Another group of 24 animals was inoculated only. On day 4, 7, 14 and 28 after inoculation the status of the drum was inspected under the otomicroscope for vascular reaction, effusion, perforation, myringosclerosis and scarring. RESULTS: On day 4 after inoculation all infected ears had typical signs of acute otitis media. Tympanic membranes healed with scar formation in most cases of myringotomized Streptococcus pneumoniae type 3 infection and deposition of sclerotic plaques was observed by day 14. Otomicroscopically visible myringosclerosis was not found after non-typeable Haemophilus influenzae induced acute otitis media neither in myringotomized nor in non-myringotomized animals. We conclude that Streptococcus pneumoniae type 3 provokes a severe clinical course of acute otitis media that healed with scarring and myringosclerosis formation in the tympanic membrane. Clinically visible myringosclerosis develops after middle ear infection caused by Streptococcus pneumoniae type 3, but not in cases caused by non-typeable Haemophilus influenzae.

Acute Disease↗
PubMed2005

[Inhibition effect of methylene blue on the acids production of Streptococcus mutans].

OBJECTIVE: To study the effect of methylene blue on the growth and acid production of Streptococcus mutans, and the effect of methylene blue on acid production metabolism in plaque glycolysis model (i-PGM) in vitro, and investigate the practicability of methylene blue as a new kind of dental caries prevention agent. METHODS: Nephelometer method was used to measure OD value of Streptococcus mutans culture fluid in the different incubation conditions. The kinds and quantities of acid produced by Streptococcus mutans in the different incubation conditions were measured with gas chromatography. pH values of glycolysis buffer media of i-PGM in the different treatment conditions were measured by ORION electrode. RESULTS: (1) The OD value of Streptococcus mutans treated by methylene blue was lower than that by normal saline, and there was significant statistical difference between them. (2) The kinds of acid in three different culture fluid were same, but the total quantities of acid were significantly different among three different culture fluid, in which the total quantities of acid of culture fluids treated by glucose was the greatest, and treated by methylene blue was the lest. (3) The pH value of i-PGM treated by methylene blue was significantly different compared with negative control group, but was not significantly different compared with positive control group. CONCLUSION: Methylene blue can inhibit the growth and acid production metabolism of Streptococcus matans and acid production metabolism of i-PGM.

Dental Caries↗
PubMed2005

[Rapid detection of Streptococcus pneumoniae and Haemophilus influenzae with DNA probes].

OBJECTIVE: To establish a method for rapid molecular detection of Streptococcus pneumoniae and Haemophilus influenzae in the early stage of infection. METHODS: Specific DNA probes for Streptococcus pneumoniae and Haemophilus influenzae and 16 S rRNA universal probe of bacteria were synthesized by polymerase chain reaction (PCR) and labeled with biotin. The DNA of the bacteria, virus and fungi were hybridized with these probes respectively prior to application for examination of the clinical samples. RESULTS: The DNA probes of 263, 351, and 370 bp were amplified by PCR. Streptococcus pneumoniae and Haemophilus influenzae reacted only with their corresponding probes, and no cross reaction of the bacterial universal probe with virus and fungi was noted. The method could detect bacterial DNA in as small amount as 1 ng. Of the 100 sputum specimens, 11 were found to be positive for Streptococcus pneumoniae and 8 for Haemophilus influenzae, with a positivity rate greater than that by sputum culture. CONCLUSION: DNA probe detection is simple, rapid, and specific for clinical examination of Streptococcus pneumoniae and Haemophilus influenzae.

DNA Probes↗
PubMed2005

[Matched case-control study for risk factors of human Streptococcus suis infection in Sichuan Province, China].

OBJECTIVE: To study the potential risk factors of human infecting with Streptococcus suis. METHODS: 1: M matched case-control study was conducted. 29 human cases of Streptococcus suis infection in the early phase were included in the case group, Patients' family members, neighbors and peoples who had worked together with patients to handle deceased or sick pigs in the last week were recruited as matched controls. There were 147 controls in total. Both cases and controls received questionnaire investigation including the ways to contact sick/dead pigs. Conditional logistic regression was employed to analyze matching data. RESULTS: According to the results of multivariate analysis, slaughtering (OR = 11.978, 95% CI: 3.355-42.756), carcasses cutting and processing (OR = 3.008, 95% CI: 1.022-8.849) sick/dead pigs were associated with cases related to human Streptococcus suis infection. The attributable risk proportion were 91.65% and 66.76% respectively. The other types of exposures to sick/ dead pigs, including feeding, selling, burying and eating, were not associated with the human Streptococcus suis infection in our study population. CONCLUSION: Slaughtering, carcasses cutting and processing sick/dead pigs were important risky behavior for humans to be infected by Streptococcus suis.

Adult↗
PubMed2005

Early acquisition of Streptococcus mutans for children.

Existing evidence reveals that in Early Oral Infection the main route of transmission of Streptococcus mutans is mother-child saliva contacts and that initial acquisition takes place during a specific period of time denominated "Window of Infectivity" that lapses between 6 and 30 months of the child's life, with a higher risk between 18 and 30 months of age. The aim of the present study was to analyze Early Oral Infection. The levels of Streptococcus mutans in saliva and bacterial plaque in the binomial mother-child 6 to 18 months after childbirth were evaluated. Twenty-four mother-child binomials that attended the University Hospital of Maternity and Neonatology of Córdoba participated in the study. Samples of saliva and dental plaque were taken from mother and child and seeded in selective Agar Mitis Salivarius Bacitracin medium (0.28 mg/ml) and cultured for 48 hours at 37 degrees C and in 5% CO2 to allow for the growth of Streptococcus mutans. The colonies were identified morphologically and biochemically. At 6 months after childbirth: 58.33% of the samples of the mother's saliva were positive, while the presence of the microorganism was not detected in 100% of the samples of the infants' saliva. At 18 months of after childbirth: 79.16% of the samples of saliva and 100% of the samples of the mothers' dental plaque were positive, whereas the samples of saliva and dental plaque of the infants were positive for Streptococcus mutans in 20.83% and 70.83% of the cases respectively. The initial acquisition of Streptococcus mutans would have occurred in 20.8% of the children at the age of 18 months. Eruption of primary molars occurs at this age.

Age Factors↗
PubMed1990

Serogrouping of oral Streptococcus intermedius.

Employing twenty fresh oral isolates of Streptococcus intermedius, studies were carried out to characterize serological relations among the isolates and also between the isolates and the strains of bacterial species closely related to S. intermedius. The Rantz-Randall extracts from the cells were used as antigens. The anti-rabbit serum raised against S. intermedius ATCC 27335T reacted with the cell extracts from only three strains of the isolates, which were designated serogroup I strains. The other isolates were classified into four serogroups, I, III, IV, and V, which specifically reacted with the cell extracts from the homologous serogroup strains. However, the serogroup II antiserum formed in immunodiffusion a common precipitin line between the extracts from the cells of serogroups II and I. The serogroups I, III, IV, and V antisera reacted with none of the extracts from the bacterial cells closely related to S. intermedius, which included Streptococcus anginosus ATCC 33397T, Streptococcus constellatus ATCC 27823T, three NCTC strains of "Streptococcus milleri," and three ATCC strains of Streptococcus MG. The precipitin line formed by the homologous reaction of the serogroup II antiserum was found to be a reaction of identity with that formed by the extract from "S. milleri" NCTC 10708. Conversely, the antiserum against NCTC 10708 strain did not react with the cell extracts of serogroup II.

Animals↗
PubMed1989

[Taxonomic studies of the Streptococcus intermedius strains isolated from human oral cavities].

Human oral isolates of Streptococcus intermedius, which were biochemically identified, have been classified into 5-Serogroups (I-V). Selecting some representive stock cultures together with the type strain ATCC 27335, comparisons were carried out between them in terms of cell extractable proteins, G + C mol% values, DNA-DNA homology and DNA restriction fragments. Since the taxon of S. intermedius has not been clarified, comparison was also made between the above strains and the type strains of the "Streptococcus anginosus-milleri Group", Streptococcus anginosus, "Streptococcus milleri" and Streptococcus constellatus, which were thought to be related to S. intermedius. 1. G + C mol% of S. intermedius ATCC 27335 was 38.0 +/- 0.28. The values of all the isolates tested ranged from 37.0 to 38.8. On the other hand, the values of the type strains of the "S. anginosus-milleri Group" were 38.0-38.8. 2. Under stringent conditions of DNA-DNA hybridization, all the isolates showed more than 66.7% homology with S. intermedius ATCC 27335, demonstrating that these strains belonged to the same species. On the other hand, S. anginosus ATCC 33397, "S. milleri" NCTC 11169 and S. constellatus ATCC 27823 hybridized at levels of 50%, 53% and 28%, respectively. Consequently, it was impossible to classify these strains as being the same species as S. intermedius. 3. When the DNA restriction fragments were compared by PAGE, the strains of Serogroups I and V showed the same pattern, respectively. The strains of Serogroups II and III, however, showed two different patterns, and these of Serogroup IV showed five different patterns. DNA fragments specific to S. intermedius could not be identified. 4. When cell extractable groups were compared by SDS-PAGE, the strains of Serogroups I and V showed identical patterns. The strains of Serogroup III showed 2 different patterns and those of Serogroup IV showed 5 patterns. These results reflected those of the DNA restriction analysis. However, the strains of Serogroup II showed the same protein pattern, although 2 different patterns were observed in DNA restriction fragments. Unique proteins, which were not detected in the proteins extracted from the type strains of the "S. anginosus-milleri Group", were observed in the cell proteins of S. intermedius strains. 5. The results of DNA-DNA hybridization and the existence of unique extractable proteins together with the chondroitinase productivity suggest that the strains of S. intermedius might represent a particular taxon among the strains of the "S. anginosus-milleri Group".(ABSTRACT TRUNCATED AT 400 WORDS)

Humans↗
PubMed1983

Effects of xylitol on the acid production activity from sorbitol by Streptococcus mutans and human dental plaque.

-A method for the determination of acid production from 20-25 mg (wet weight) of Streptococcus mutans and 12-33 mg (wet weight) of human dental plaque is described. After endogenous acid production had been followed, either sorbitol or xylitol or a mixture of sorbitol and xylitol (2:1) was added. After about ten minutes glucose, sucrose or Palatinose were added for a vitality test. Addition of xylitol to the bacterial suspension caused inhibition of acid production from sorbitol by Streptococcus mutans grown on sorbitol or a mixture of sorbitol and glucose. It was also observed that it had a similar effect on acid production from sorbitol in suspensions of dental plaque with few exceptions. On the other hand, Streptococcus mutans cells grown on glucose, sucrose and xylitol media, produced no or insignificant amounts of acid from sorbitol. Streptococcus mutans cells grown on media containing glucose, sucrose, sorbitol and a mixture of sorbitol and glucose generally formed a large amount of acid from glucose and sucrose after the addition of sorbitol and xylitol. However, Streptococcus mutans cells grown on a medium containing xylitol and the mixture of sorbitol and xylitol formed less acid from glucose. The acid production activity from sorbitol in suspensions of dental plaque after the xylitol addition was somewhat lower than the acid production from sorbitol alone (p less than 0.02).

Acids↗
PubMed1993

Evaluation of two rapid tests for detection of maternal endocervical group B streptococcus: enzyme-linked immunosorbent assay and gram stain.

OBJECTIVE: To establish the reliability of two rapid tests for detection of group B streptococcus, the new enzyme-linked immunosorbent assay (ELISA) and the Gram stain. In addition, we wished to determine whether the combination of these tests would increase test sensitivity. METHODS: During a 2-year period, cervical secretions from 660 patients who presented with either premature rupture of membranes or preterm labor at a gestational age of 37 weeks or less were tested by three methods: the Equate ELISA test, a Gram stain smear, and a culture for group B streptococcus. Results of the rapid tests were compared with the corresponding culture results. RESULTS: Cultures were positive for group B streptococcus in 50 patients, a prevalence of 7.5%. The sensitivity for the Equate ELISA test was 24% and for the Gram stain, 20%. Specificity was 95 and 89%, respectively. When results of these tests were combined, the sensitivity increased to 26%. Both rapid tests yielded a high rate of false positives. In more than 50% of false-positive cases, bacteria other than group B streptococcus were isolated. CONCLUSION: Neither the Gram stain nor the Equate ELISA test is sensitive enough to be used as a screening test for the identification of group B streptococcus. Furthermore, the combination of both rapid tests yielded only a slight increase in sensitivity. The high false-positive rate of the ELISA test seems to be related to a cross-reactivity of the anti-group B streptococcal antibody with other cervical bacteria.

Cervix Uteri↗
PubMed1994

[Behavior of Streptococcus mutans under prolonged exposure to xylitol, without reculture].

Previous studies carried out in our laboratory showed that Streptococcus mutans--a cariogenic oral bacteria--did not metabolize an anticariogenic sugar alcohol, xylitol, even after a 10-month adaptative period with monthly transfers to a fresh medium. Due to the potential risk to adaptation observed in bacterias, it was studied the behavior of Streptococcus mutans (Strain 1161, Ingbritt) exposed to the polyol during 7 months, without monthly transfers to a new medium. After 7 months the cells were monthly transferred to a fresh medium for 7 more months. The cells were maintained and grown in a Trypticase-soytone-base medium without dextrose which contained xylitol (0.25 g/100 mL) or no sugar added. The control was represented by cells of Streptococcus mutans growing in Trypticase- soytone-base medium containing dextrose (0.25 g/100 mL). The growth pattern in the presence of xylitol was similar to that obtained in the cultures without sugar added, but it was 63-78% lower when compared with the control. The final pH in the cultures with xylitol was around 6.0; in the control it was very low (4.69 +/- 0.12). When the cells maintained in xylitol were transferred to the medium containing dextrose, the growth pattern was similar to that of the control. Any cultures fermented xylitol; the pH of the fermentation medium remained around 6.00 when the xylitol was present. No uptake of 14C-xylitol was observed and the activity of the enzyme xylitol dehydrogenase could not be detected with the experimental procedure used. The present study confirmed the Streptococcus mutans inability to metabolize xylitol, even after a prolonged adaptative period in the sugar alcohol. Moreover, it demonstrated that xylitol could be considered an inert substance to Streptococcus mutans since the cells were viable in the presence of the xylitol, or in the medium without sugar added.

Bacteriological Techniques↗
PubMed1997

Effect of Cervitec varnish on the salivary Streptococcus mutans levels in the patients with fixed orthodontic appliances.

The aim of the present study was to assess the efficiency of a 1% chlorhexidine-containing varnish (Cervitec, Vivadent, Liechtenstein) on the levels of Streptococcus mutans in saliva of patients with fixed orthodontic appliances using the Dentocult-SM (Vivadent, Liechtenstein) technique for the microbiological investigation. Eighty subjects participated in the study and, divided randomly into two equal groups in which one group was treated with the placebo varnish (Vivadent, Liechtenstein) for negative controls. Streptococcus mutans in saliva of the subject was sampled and enumerated by using the Dentocult-SM dip-slide technique for periods of one, two four and twelve weeks after a single varnish application. The results were evaluated statistically. After the chlorhexidine containing varnish treatment the levels of Streptococcus mutans in saliva were significantly reduced after one week (p < 0.01) and continued reduction for one month (p < 0.05). After twelve weeks Streptococcus mutans levels in saliva were given a relative increase. No significant suppression was found in the placebo group (p > 0.05). The results suggested that Cervitec varnish reduces salivary Streptococcus mutans levels and that the application should be repeated every 3 months to get antibacterial effect.

Adolescent↗
PubMed2002

An essential amino acid residue for catalytic activity of the dextranase of Streptococcus mutans.

Dextranase (Dex) is an enzyme that hydrolyzes glucan, a polymer of glucose synthesized from sucrose by glucosyltransferases (GTFs). By comparing amino acid sequences of Dexs and GTFs, we found that the Dex enzymes of Streptococcus mutans, Streptococcus sobrinus, Streptococcus downei and Streptococcus salivarius had similar amino acid sequences to those of the catalytic sites of GTFs of mutans streptococci. We therefore examined the amino acid essential in Dex catalysis by molecular genetic approaches in this study. Site-directed mutagenesis was used to convert the Asp-385 of the Dex molecule of S. mutans Ingbritt to Glu, Asn, Thr or Val. Replacement of Asp-385 with any of the amino acids resulted in complete disappearance of Dex activity. However, replacement of other Asp residues did not affect the enzyme activity. The inactive enzymes still retained dextran-binding ability. These results suggest that Asp-385 of the Dex of S. mutans Ingbritt was essential for enzyme activity and the catalytic and substrate-binding sites were located at different sites within the Dex molecule.

Amino Acid Sequence↗
PubMed1982

Adsorption of lysozyme from human whole saliva by Streptococcus sanguis 903 and other oral microorganisms.

Several strains of Streptococcus sanguis, Streptococcus mutans, Streptococcus mitis, Actinomyces viscosus, and Actinomyces naeslundii plus fresh isolates of Streptococcus salivarius were surveyed for their abilities to deplete lysozyme from human-whole-saliva supernatant. Bacteria were incubated in saliva for 60 min at 37 degrees C and then removed by centrifugation, and the recovered supernatant solutions were assayed for lysozyme activity by using whole cells of Micrococcus lysodeikticus as the substrate. Mean lysozyme depletions by bacterial strains varied over a wide (eightfold) range. The greatest mean depletion of lysozyme (60 to 70%) was observed with S. sanguis (biotype I), serotype b of S. mutans, and the fresh S. salivarius isolates. The lowest mean depletion was noted with S. mitis (15%) and biotype II S. sanguis (ca. 30%). The remaining species and strains exhibited an intermediate degree of depletion. In studies with S. sanguis 903, lysozyme was depleted by normal or heated (90 degrees C, 30 min) bacteria and could be recovered from the organism. Furthermore, under appropriate conditions, lysozyme depletion by cells at 0 and 37 degrees C was very similar. On the basis of these observations, we concluded that depletion was due to the adsorption of lysozyme by the organism. With S. sanguis 903, lysozyme adsorption depended on the concentration of bacteria, time of incubation, and the ionic strength of the medium. The extent of adsorption, however, was independent of pH's of 3.9 to 8.3. When a low concentration of S. sanguis 903 was used, lysozyme adsorption reached saturation (4 mug of adsorbed lysozyme per 10(7) cells) at 20 mug of lysozyme added per ml. Salivary lysozyme adsorption by several other oral microorganisms (A. viscosus WVU 626 and WVU 627, S. sanguis 73x11, S. mutans BHT, and S. salivarius NG) was similar to that of S. sanguis 903 in sensitivity to ionic strength. Lysozyme adsorption by S. sanguis 903 from either a buffer solution or a saliva supernatant was more sensitive to ionic strength at 0 than at 37 degrees C. On the basis of results from experiments in saliva versus buffer, we concluded that saliva had no major effect on the extent of lysozyme adsorption by S. sanguis 903 other than providing a source of ionic strength. A comparison of pH and ionic strength effects on lysozyme adsorption by S. sanguis 903 with literature reports of lysozyme lysis of whole cells and hydrolysis of cell walls, peptidoglycan, and (GlcNAc)(4) suggested that adsorption by S. sanguis 903 was more dependent on electrostatic interactions than was lysozyme catalysis. The possibility is discussed that anionic bacterial surface components mediate lysozyme adsorption and temper the potential effects of lysozyme on the microorganisms.

Actinomyces↗
PubMed2005

Discrimination of Streptococcus pneumoniae from viridans group streptococci by genomic subtractive hybridization.

Two oligonucleotide primer sets for the discrimination of Streptococcus pneumoniae from "pneumococcus-like" oral streptococcal isolates by PCR were developed. Genomic subtractive hybridization was performed to search for differences between Streptococcus pneumoniae strain WU2 and the most closely related oral streptococcus, Streptococcus mitis strain 903. We identified 19 clones that contained S. pneumoniae-specific nucleotide fragments that were absent from the chromosomal DNA of typical laboratory strains of S. mitis and other oral bacteria. Subsequently, oligonucleotide PCR primers for the detection of S. pneumoniae were designed from the sequences of the subtracted DNA fragments, and the specificities of the 19 primer sets were evaluated by PCR using chromosomal DNAs extracted from four S. pneumoniae clinical isolates and from 20 atypical organisms classified as S. mitis or S. oralis, which harbored genes encoding the pneumococcal virulence factors autolysin (lytA) or pneumolysin (ply), as templates. Of the 19 primer sets, two (Spn9802 and Spn9828) did not amplify PCR products from any of the pneumococcus-like streptococcal strains that we examined. The genes containing the Spn9802 and Spn9828 sequences encoded proteins of unknown function that did not correspond to any previously described proteins in other bacteria. These new oligonucleotide primers may be very useful for early and correct diagnosis of S. pneumoniae infections.

Bacterial Proteins↗
PubMed1991

Comparison of the physicochemical surface properties of Streptococcus rattus with those of other mutans streptococcal species.

Mutans streptococci comprise a group of seven closely related, yet distinct species. The distinction between the four species used in this study, namely Streptococcus sobrinus, Streptococcus cricetus, Streptococcus rattus, and Streptococcus mutans, has been made only recently on the basis of DNA homologies. In order to determine if there is a difference in the physicochemical surface properties of these species, strains were characterized by contact angles, zeta potentials and isoelectric points (IEP), elemental surface compositions by X-ray photoelectron spectroscopy, and molecular moieties by infrared spectroscopy. Contact angles, particularly when measured with water, can be considered a measure of cell surface hydrophobicity; zeta potentials reflect the charge of the outermost cell surface; X-ray photoelectron spectroscopy yields the relative abundance of carbon, oxygen, nitrogen, and phosphorus over the outer 5 nm of the bacterial cell surface; infrared spectroscopy enables a molecular characterization in terms of proteins, phosphates, and polysaccharides. All four species were homogeneous with regard to their physicochemical surface properties. However, the S. rattus species were clearly different from the others on the basis of the low water contact angle (21 +/- 2 vs. 26-31 degrees), highly negative zeta potential and lack of IEP, and high oxygen/carbon (0.50 +/- 0.02 vs. 0.41-0.43) and phosphorus/carbon (0.016 +/- 0.001 vs. 0.006-0.008) surface concentration ratios. Amongst the other differences observed, each species had a characteristic pH dependence of their zeta potential measured in phosphate buffer, yielding an IEP of 1.7, 2.1, and 2.5 for S. cricetus, S. sobrinus, and S. mutans, respectively. However, a cluster analysis on the zeta potential data showed only an isolated cluster for the S. rattus species. Thus it is likely that the higher cariogenicity of S. sobrinus with respect to S. cricetus and S. mutans is, in addition to a higher acidogenicity, due to the smaller negative surface charge, giving an increased adhesion to negatively charged tooth surfaces. S. rattus is expected to be the least adherent strain in the oral cavity as it carries a relatively high negative surface charge.

Cell Membrane↗