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At least 613 records · Page 34Linked to original sources
PubMed2006

Molecular characterization of subject-specific oral microflora during initial colonization of enamel.

The initial microbial colonization of tooth surfaces is a repeatable and selective process, with certain bacterial species predominating in the nascent biofilm. Characterization of the initial microflora is the first step in understanding interactions among community members that shape ensuing biofilm development. Using molecular methods and a retrievable enamel chip model, we characterized the microbial diversity of early dental biofilms in three subjects. A total of 531 16S rRNA gene sequences were analyzed, and 97 distinct phylotypes were identified. Microbial community composition was shown to be statistically different among subjects. In all subjects, however, 4-h and 8-h communities were dominated by Streptococcus spp. belonging to the Streptococcus oralis/Streptococcus mitis group. Other frequently observed genera (comprising at least 5% of clone sequences in at least one of the six clone libraries) were Actinomyces, Gemella, Granulicatella, Neisseria, Prevotella, Rothia, and Veillonella. Fluorescence in situ hybridization (FISH) confirmed that the proportion of Streptococcus sp. sequences in the clone libraries coincided with the proportion of streptococcus probe-positive organisms on the chip. FISH also revealed that, in the undisturbed plaque, not only Streptococcus spp. but also the rarer Prevotella spp. were usually seen in small multigeneric clusters of cells. This study shows that the initial dental plaque community of each subject is unique in terms of diversity and composition. Repetitive and distinctive community composition within subjects suggests that the spatiotemporal interactions and ecological shifts that accompany biofilm maturation also occur in a subject-dependent manner.

Actinomyces↗
PubMed2003

NO synthesis in human saliva.

Human saliva contains nitrate that is converted into nitrite by the activity of facultative, anaerobic bacteria of the oral cavity. Nitrite can be reduced to NO in the acidic gastric milieu; some NO may also form in the mouth at acidic pH values. In this paper, we show that bacteria (S. salivarius, S. mitis and S. bovis) isolated from saliva, may contribute to NO production in human saliva. NO formation by bacteria occurs at neutral pH values and may contribute to the antibacterial activity of saliva.

Adult↗
PubMed1999

[Analysis of serum antibodies to alpha-streptococci in patients with tonsil-related pustulosis palmaris et plantaris].

To determine the systemic immune response to alpha-streptococci (Str. sanguis, Str. salivarius and Str. mitis) and beta streptococcus (Str. pyogenes T12) in patients with tonsil related pustulosis palmaris et plantaris (PPP), we measured serum antibody levels to whole cell body antigens of Streptococcus (Str.) sanguis, Str. salivarius, Str. mitis or Str. pyogenes by enzyme-linked immunosorbent assay (ELISA). The serum IgG antibody levels to alpha-streptococci, Str. sanguis and Str. salivarius were significantly higher in patients with PPP (n = 44) than in patients with recurrent tonsillitis (RT: n = 25) and in healthy adults (n = 17). Serum antibody IgG level to Str. pyogenes was not different among the 3 groups. The IgA antibody levels against any Streptococcus strain were not different among the 3 groups. The IgM antibody levels to Str. pyogenes were significantly higher in patients with RT than in patients with PPP. In western blot analysis, the serum IgG antibodies against 25-27 kDa protein from whole cell body of Str. sanguis, Str. salivarius and Str. mitis were found more frequently in patients with PPP than in healthy adults. However, the western blot profile in Str. pyogenes was not different between PPP and healthy adults. No significant difference was seen in the western blot profile of IgM or IgM antibodies to any streptococcal whole cell bodies. These data suggest that systemic hyper immune response to alpha-streptococci may be present in patients with tonsil-related PPP and the 25-27 kDa protein of the organism may be the target for this immunologic abnormality.

Adult↗
PubMed2026

Clinical and genomic features of mitis group streptococcal bacteremia in patients with febrile neutropenia.

BACKGROUND: Viridans group streptococci (VGS) can cause the life-threatening viridans streptococcal shock syndrome (VSSS) in patients with febrile neutropenia (FN). The Mitis group, a major subgroup of VGS, is frequently implicated in these severe infections, but its specific clinical and genomic characteristics remain incompletely characterized, particularly in patients with FN. This study aimed to systematically describe these features in this population. METHODS: In this single-center retrospective study, we compared the clinical data and whole-genome sequencing (WGS) results of Mitis group streptococcal isolates from patients with and without FN. Virulence-associated and antimicrobial resistance genes were initially screened using a reference-based approach, followed by assembly-based reanalysis and manual sequence validation. RESULTS: Compared with the non-FN cohort (n = 34), the FN cohort (n = 61) was significantly younger, had a higher prevalence of hematologic malignancy, and more frequently presented with primary bacteremia. VSSS occurred exclusively in the FN group (11.5%) and was associated with high mortality (14-day mortality, 42.9%), which did not correlate with in vitro antimicrobial susceptibility. Genomic analyses revealed marked diversity among isolates. Initial screening suggested variable detection of several virulence-associated loci, including pavA, slrA, and rfb-related loci; however, subsequent assembly-based analyses indicated that many apparent absences were attributable to extreme allelic divergence rather than true gene loss. No single virulence determinant clearly segregated with clinical severity. CONCLUSIONS: Mitis group bacteremia in patients with FN appears to be characterized by distinct clinical features and marked genomic diversity. Our findings suggest that the development of severe disease, including VSSS, may not be explained by microbial factors alone and potentially reflects complex host-pathogen interactions. CLINICAL TRIAL: Not applicable.

Humans↗
PubMed2002

Effect of medium composition on the susceptibility of oral streptococci to mercuric chloride.

Although there is considerable interest in identifying mercury-resistant bacteria, no standardized assay exists for this purpose. In this study, the effect of the composition of the medium on the susceptibility of oral streptococci to HgCl(2) was investigated. The minimum inhibitory concentration (MIC) of HgCl(2) for 52 streptococcal strains and the reproducibility of MIC values for Hg-sensitive and Hg-resistant strains was determined with 11 different media. Addition of blood increased the MIC values, and some media (tryptone soya agar, with or without blood) could not discriminate between Hg-sensitive and Hg-resistant strains. The proportion of streptococci that appeared to be resistant to Hg was very high (>70%) on some media (mitis-salivarius, tryptone soya, Columbia), but not on others (Mueller-Hinton, Brain Heart Infusion, Isosensitest). The MICs of the control strains varied considerably on different testing occasions for tryptone soya agar (with and without blood), Isosensitest agar, and Columbia agar (with blood). Mueller-Hinton (without blood) appeared to be the most suitable medium for isolating Hg-resistant oral streptococci.

Agar↗
PubMed2004

Investigation of the effect of the coronal restoration quality on the composition of the root canal microflora in teeth with apical periodontitis by means of T-RFLP analysis.

AIM: To investigate the effect of the radiographic and clinical quality of coronal restorations on the composition of the root canal flora of teeth with necrotic pulps and teeth with root fillings associated with apical periodontitis. METHODOLOGY: Twenty-eight necrotic pulps and 35 root filled canals with signs of apical periodontitis were studied. Both the coronal filling (presence of radiographically or clinically deficient margins and/or secondary caries) and the root filling (homogeneity and length) were scored. Bacterial root canal samples were taken with sterile paper points under rubber dam and using measures to prevent contamination. A DNA-based nonculture bacterial identification technique was used, namely terminal restriction fragment length polymorphism (T-RFLP) analysis. RESULTS: Twelve samples were negative for bacterial DNA. A total of 33 different terminal restriction fragments (TRFs) were detected. The Fusobacterium nucleatum/Streptococcus mitis group was the most frequently encountered TRF. The mean number of TRFs per necrotic pulp was 6.2 and 5.8 for the groups with acceptable and unacceptable coronal restorations, respectively. This difference was not significant. In the root filled group, these values (respectively, 5.2 and 8.6) were statistically significantly different (P < 0.05). The following parameters in root filled teeth had no significant influence on the mean numbers of TRFs detected: the length and homogeneity of the root filling and the type of tooth (anterior-premolar-molar). CONCLUSION: T-RFLP allowed the rapid assessment of bacterial biodiversity in root canal samples. The technique revealed the presence of bacteria that have rarely been described in the root canals of teeth with apical periodontitis. Biodiversity in the root filled group was high, as compared with culture-dependent studies where monoinfections were more frequently reported. Only in root filled teeth did defective coronal restorations have a statistically significant influence on the mean numbers of detected TRFs per sample.

Adult↗
PubMed2003

[Undetected hypopharyngeal perforation with deep neck abscess and mediastinitis due to transesophageal echocardiography].

Hypopharyngeal perforation is a rare but dangerous complication caused by diagnostic procedures. If there is any suspicion of perforation of the upper airways and/or upper digestive tract, immediate diagnostic and therapeutic procedures are indicated. Possible complications of a hypopharyngeal perforation are deep neck infection with subsequent mediastinitis and haemorrhage from major cervical vessels, both of which have high mortality rates. We present the case of a 65 year old male patient with perforation of the hypopharynx after transesophageal echocardiography which was unrecognized for more than 1 week. Clinical symptoms of hypopharyngeal perforation may initially be unspecific. Esophagography (Gastrografin administration) and computed tomography as well as esophagoscopy are needed to certify the diagnosis and to evaluate the extent of the lesion. Pathological findings as well as diagnostic and therapeutic needs are demonstrated and discussed.

Aged↗
PubMed2004

A case of delayed brain abscess due to a retained intracranial wooden foreign body: a case report and review of the last 20 years.

A 13-year-old female is presented. When she was six years old, she had fallen, holding wooden chopsticks and got stuck with a chopstick in the right upper eyelid. She was brought to a physician immediately, but a residual foreign body was missed and no particular symptom had developed during 7 years. She visited our department with fever and headache, and a brain abscess and an intracranial foreign body were found on computed tomography (CT) and magnetic resonance image (MRI) 7 years after the penetrating injury. She underwent removal of the object and abscess by craniotomy and recovered without neurological abnormalities. Since intracranial retained wooden foreign bodies frequently cause delayed complications of severe central nervous system infection, surgical removal is necessary even in the absence of symptoms.

Adolescent↗
PubMed2005

The vital status of human buccal epithelial cells and the bacteria associated with them.

OBJECTIVE: We have shown that buccal epithelial cells (BEC) from humans can contain a polymicrobial intracellular flora. Members of that flora can induce proinflammatory responses. However, our subjects all had healthy oral mucosa. This might reflect tolerance of bacterial invasion by live BEC. Alternatively, inflammation might not occur if invaded cells were mostly dead, and thus unable to mount a response. This study addressed that issue, by determining the vital status of BEC and the bacteria associated with them. DESIGN: Initial experiments indicated that BEC were anomalously permeable to the DNA stain propidium iodide. We used that property to develop a protocol that combined the DNA stains SYTO 9 and propidium iodide (indicators of bacterial viability) with the esterase substrate calcein blue AM (an indicator of BEC viability), and Annexin V Alexa Fluor 647 conjugate (an apoptosis marker). That protocol was applied to BEC collected from 36 human subjects. RESULTS: On average, 70% of BEC displayed calcein blue staining, with no binding of Annexin V, 25% showed signs of apoptosis, and 5% did not stain with calcein blue. The mean percent of BEC with live cell-associated bacteria was 29%. Collectively, 25% of total BEC displayed calcein blue staining and live (SYTO 9 stained) bacteria. Only 1% of total BEC were negative for calcein blue and associated with live bacteria. CONCLUSIONS: Our findings suggest that live BEC are tolerant of bacterial invasion. This may be due to complex interactions between members of the polymicrobial flora and their host BEC.

Adult↗
PubMed1991

[Reducing vaginal flora by preoperative disinfection].

In 70 gynaecological patients vaginal disinfection by povidone-iodine and chlorhexidine solution (LEC) was investigated. The preoperative bacterial spectrum corresponded to the specifications in literature. Only lactobacilli were found in fewer cases than expected, an effect, which was explained by the povidone-iodine sanitation of the vagina a day before the operation. In cases of disturbed lactobacilli flora, facultative pathogen species were found in high concentrations up to 10(6) CFU/ml. Germ reduction achieved more than 3.4 log CFU/ml in the three groups of antiseptics. Povidone-iodine left a residue of other bacteria species in one-fifth of the cases, one of the LEC-solutions only in one-tenth of the cases. B-Streptococcus, Streptococcus viridans (mitis) and Candida glabrata were found in concentrations up to 10(3) CFU/ml in the residues. In these cases, a disturbed ecology of the vagina had already existed previously. It is concluded, not to disturb normal vaginal flora needlessly before preoperative disinfection and to restore it as soon as possible after operation. The LEC solutions appeared to be a competent alternative to povidone-iodine solution in vaginal disinfection.

Administration, Intravaginal↗
PubMed2006

Incidence and behaviour of Tn916-like elements within tetracycline-resistant bacteria isolated from root canals.

INTRODUCTION: Tetracycline resistance is commonly found in endodontic bacteria. One of the most common tetracycline-resistance genes is tet(M), which is often encoded on the broad-host-range conjugative transposon Tn916. This study aimed to determine whether tet(M) was present in bacteria isolated from endodontic patients at the Eastman Dental Institute and whether this gene was carried on the transferable conjugative transposon Tn916. METHODS: The cultivable microflora isolated from 15 endodontic patients was screened for resistance to tetracycline. Polymerase chain reactions for tet(M) and for unique regions of Tn916 were carried out on the DNA of all tetracycline-resistant bacteria. Filter-mating experiments were used to see if transfer of any Tn916-like elements could occur. RESULTS: Eight out of 15 tetracycline-resistant bacteria isolated were shown to possess tet(M). Furthermore, four of these eight were shown to possess the Tn916-unique regions linked to the tet(M) gene. Transfer experiments demonstrated that a Neisseria sp. donor could transfer an extremely unstable Tn916-like element to Enterococcus faecalis. CONCLUSIONS: The tet(M) gene is present in the majority of tetracycline-resistant bacteria isolated in this study and the conjugative transposon Tn916 has been shown to be responsible for the support and transfer of this gene in some of the bacteria isolated.

Bacteria↗
PubMed1992

Screening for Corynebacterium diphtheriae.

A throat swab from a 9 year old girl with pharyngitis yielded a non-toxigenic strain of Corynebacterium diphtheriae var mitis and Streptococcus group G. C pseudodiphtheriticum was isolated from the throats of two of her four brothers. In each case the isolate was sent to the reference laboratory before full identification. The growth was found to be mixed for one brother; the other isolate being a toxin producing C diphtheriae var gravis. The child was asymptomatic and the case proves that all colonial types on the Hoyles plate should be identified.

Child↗
PubMedDate not supplied

Streptococcus cristatus isolated from a resected heart valve and blood cultures: case reports and application of phenotypic and genotypic techniques for identification.

BACKGROUND: Viridans streptococci are known as an important cause of endocarditis, but at present no cases of endocarditis caused by Streptococcus cristatus have been published, probably because phenotypic identification of viridans streptococci is tedious. Using tDNA-PCR, it is possible to identify to species level and to differentiate between species of the viridans group.

Adult↗