Detection of Helicobacter pylori by PCR on gastric biopsy specimens taken for CP test: comparison with histopathological analysis.

The aims of the present study were: (i) to assess whether H. pylori could be succesfully detected by PCR from the same biopsy sample used for CPtest; and ii) to evaluate CPtest comparatively to both PCR and histology for detection of H. pylori infection in dyspeptic patients. Three antral gastric biopsies were collected from each of 80 consecutive dyspeptic patients undergoing oesophagogastroduodenoscopy. Two biopsies were for histology (gold standard), one for CPtest, scored at 20min, 1h and 24h for the presence of urease activity. Gastric biopsy was then removed from CPtest and used for ureC-targeted PCR. Fifty-five (68.7%) patients were positive for H. pylori infection by histology. CPtest yielded an overall diagnostic accuracy of 93.8% (95% CI: 91–96.4%), regardless of observation period. No erroneous categorization of H. pylori status occurred using PCR, yielding sensitivity, specificity, positive and negative predictive values, and overall diagnostic accuracy of 100%. Our results suggest that H. pylori can be detected by PCR in gastric biopsies previously taken for CPtest, so reducing the workload of the endoscopist by saving additional biopsies for culture analysis and susceptibility tests

Comparison of culture methods and multiplex PCR for the detection of periodontopathogenic bacteria in biofilm associated with severe forms of periodontitis

Conventional culture methods and Multiplex PCR, both of which we have been used for a long time in our clinical microbiology laboratory, were compared for their ability to detect a selected panel of periodontopathic bacteria: Aggregatibacter actinomycetemcomitans, Campylobacter rectus, Eikenella corrodens, Fusobacterium nucleatum, Porphyromonas gingivalis, and Prevotella intermedia. Tests were performed in a single subgingival sample taken from a periodontal diseased site with a probing depth equal to or greater than 6mm. The results were compared site-bysite, taking into account the quality and the presence or absence of pathogens. 529 samples of subgingival plaque were analysed and the prevalence of the six species monitored varied in relation to the species itself and the method of detection. The most represented species is F. nucleatum, with a percentage of positive variability between 44.9% PCR and 46.5% culture test. Generally, the lowest prevalence was determined by culture test, with the exception of E. corrodens and F. nucleatum, which, unlike other bacteria, have been seen in higher percentages in culture with respect to PCR. For both methods, there was a good degree of accuracy in the determination of A. actinomycetemcomitans, C. rectus, E. corrodens, and P. gingivalis. It becomes weak for F. nucleatum and P. intermedia. Both culture and PCR techniques introduced many methodological problems when applied in oral microbiology, but the ideal technique for accurate detection of pathogens in subgingival plaque samples has yet to be developed

Adhesion to and biofilm formation on IB3-1 bronchial cells by Stenotrophomonas maltophilia isolates from cystic fibrosis patients

<p>Abstract</p> <p>Background</p> <p><it>Stenotrophomonas maltophilia </it>has recently gained considerable attention as an important emerging pathogen in cystic fibrosis (CF) patients. However, the role of this microorganism in the pathophysiology of CF lung disease remains largely unexplored. In the present study for the first time we assessed the ability of <it>S. maltophilia </it>CF isolates to adhere to and form biofilm in experimental infection experiments using the CF-derived bronchial epithelial IB3-1cell line. The role of flagella on the adhesiveness of <it>S. maltophilia </it>to IB3-1 cell monolayers was also assessed by using <it>fliI </it>mutant derivative strains.</p> <p>Results</p> <p>All <it>S. maltophilia </it>CF isolates tested in the present study were able, although at different levels, to adhere to and form biofilm on IB3-1 cell monolayers. Scanning electron and confocal microscopy revealed <it>S. maltophilia </it>structures typical of biofilm formation on bronchial IB3-1 cells. The loss of flagella significantly (P < 0.001) decreased bacterial adhesiveness, if compared to that of their parental flagellated strains. <it>S. maltophilia </it>CF isolates were also able to invade IB3-1 cells, albeit at a very low level (internalization rate ranged from 0.01 to 4.94%). Pre-exposure of IB3-1 cells to <it>P. aeruginosa </it>PAO1 significantly increased <it>S. maltophilia </it>adhesiveness. Further, the presence of <it>S. maltophilia </it>negatively influenced <it>P. aeruginosa </it>PAO1 adhesiveness.</p> <p>Conclusions</p> <p>The main contribution of the present study is the finding that <it>S. maltophilia </it>is able to form biofilm on and invade CF-derived IB3-1 bronchial epithelial cells, thus posing a rationale for the persistence and the systemic spread of this opportunistic pathogen in CF patients. Experiments using <it>in vivo </it>models which more closely mimic CF pulmonary tissues will certainly be needed to validate the relevance of our results.</p

Biofilm formation on titanium alloy and anatase-Bactercline® coated titanium healing screws: an in vivo human study

Aim Bacterial adherence to implants is considered to be an important event in the pathogenesis of bacterial infections. In fact, this infection process is a first stage of peri-implant mucositis and peri-implantitis, and a positive correlation has been found between oral hygiene and marginal bone loss around implants in the edentulous mandible. Surface properties of transgingival implant components are important determinants in bacterial adhesion. The purpose of this study was to characterize the biofilm formation, in vivo, on healing screws made of titanium alloy or coated with a combination of anatase and Bactercline® product. Materials and methods Twenty-five patients, between 21- 37 years, in excellent systemic health, participated in this study. In each of the 25 participants, one anatase-Bactercline® coated healing screw (Test) and one titanium alloy (TI6Al4V) healing screw (Control) were adapted to two different implants. Quantitative and qualitative biofilm formation on healing abutments was analyzed by culture method.Results Bacterial adherence to the two different healing screws used in this study were compared. Statistically significant differences were found between the Control and the Test group for both aerobic and anaerobic bacterial counts (p<0,05). The microflora consisted both of Gram-positive and Gram-negative bacteria, and displayed a high variability. The anaerobic S. intermedius, potentially “pathogenic”, was isolated only from the Control group. Both healing screws harbored primarily Gram-positive rods as Actinomyces spp, A. naeslundii, A. viscosus and the Gram-negative rods (Fusobacterium spp, Prevotella spp, Capnocythophaga spp) were mostly found on the Control healing screws.Conclusion Anatase-Bactercline® coated healing screws reduce the number of initially adhering bacteria, formed mainly of Gram-positive microorgnisms, while, on the contrary, the microflora covering the titanium alloy healing screws was, for the most part, Gram-negative

Biofilm Formation by Stenotrophomonas maltophilia: Modulation by Quinolones, Trimethoprim-Sulfamethoxazole, and Ceftazidime

We investigated the in vitro effects of seven fluoroquinolones (ciprofloxacin, grepafloxacin, levofloxacin, moxifloxacin, norfloxacin, ofloxacin, and rufloxacin), compared to those of trimethoprim-sulfamethoxazole (SXT) and ceftazidime on total biomass and cell viability of Stenotrophomonas maltophilia biofilm. S. maltophilia attached rapidly to polystyrene, within 2 h of incubation, and then biofilm formation increased over time, reaching maximum growth at 24 h. In the presence of fluoroquinolones at one-half and one-fourth the MIC, biofilm biomass was significantly (P < 0.01) reduced to 55 to 70% and 66 to 76% of original mass, respectively. Ceftazidime and SXT did not exert any activity. Biofilm bacterial viability was significantly reduced by all antibiotics tested at one-half the MIC. At one-fourth the MIC all antibiotics, except levofloxacin, significantly reduced viability. Treatment of preformed biofilms with bactericidal concentrations (500, 100, and 50 μg/ml) of all fluoroquinolones caused, except for norfloxacin, significant reduction of biofilm biomass to 29.5 to 78.8, 64.1 to 83.6, and 70.5 to 82.8% of original mass, respectively. SXT exerted significant activity at 500 μg/ml only. Ceftazidime was completely inactive. Rufloxacin exhibited the highest activity on preformed biofilm viability, significantly decreasing viable counts by 0.6, 5.4, and 17.1% at 500, 100, and 50 μg/ml, respectively. Our results show that (i) subinhibitory (one-half and one-fourth the MIC) concentrations of fluoroquinolones inhibit adherence of S. maltophilia to polystyrene and (ii) clinically achievable concentrations (50 and 100 μg/ml) of rufloxacin are able to eradicate preformed S. maltophilia biofilm

Microbiologia ed immunologia del cavo orale

Libro di testo per gli studenti di odontoiatri

Clinical and microbiologic effects of subgingival controlled-release delivery of chlorhexidine chip in the treatment of periodontitis: a multicenter study.

Background: The main therapeutic approach for periodontal diseases is mechanical treatment of root surfaces via scaling and root planing (SRP). Multicenter clinical trials have demonstrated that the adjunctive use of a chlorhexidine (CHX) chip is effective in improving clinical results compared to SRP alone. However, some recent studies failed to confirm these clinical results, and conflicting results were reported regarding the effects of the CHX chip on subgingival microflora. The aim of this study was to provide further data on the clinical and microbiologic effects of CHX chips when used as an adjunct to SRP. Methods: A total of 116 systemically healthy individuals with moderate to advanced periodontitis, aged 33 to 65 years, were recruited from the Departments of Periodontology of four Italian universities. For each subject, two experimental sites were chosen that had probing depths (PD) ≥5 mm and bleeding on probing (BOP) and were located in two symmetric quadrants. These two sites were randomized at the split-mouth level, with one receiving SRP treatment alone and the other receiving treatment with SRP plus one CHX chip (SRP + CHX). PD, relative attachment level (RAL), and BOP were evaluated at baseline, prior to any treatment, and after 3 and 6 months. Supragingival plaque and the modified gingival index were evaluated at baseline and after 15 days and 1, 3, and 6 months. Subgingival microbiologic samples were harvested at baseline and after 15 days and 1, 3, and 6 months, cultured for total bacterial counts (TBCs), and investigated by polymerase chain reaction analysis for the identification of eight putative periodontopathogens. Results: When all of the pockets were considered, the PD and RAL were significantly less at 3 and 6 months compared to the baseline scores (P<0.01) for both treatments. Moreover, the PD was reduced in the SRP + CHX treatment group compared to the SRP treatment group at 3 and 6 months, whereas the RAL was similar for both treatments at 3 months and was reduced in the SRP + CHX treatment group at 6 months. The differences in PD reductions between the treatments were 0.30 and 0.55 mm at 3 and 6 months, respectively (P<0.01); for the RAL gain, the differences were 0.28 and 0.64 mm, respectively (P<0.001). The TBCs decreased significantly with both treatments. A similar, although less evident, pattern was noted when only the pockets with an initial PD ≥7 mm were considered. The percentage of sites positive for BOP was similar between the treatments at each time point. At 15 days and 1 month, the TBC for the SRP + CHX treatment group was significantly lower than for the SRP treatment group (P<0.01 and P<0.05, respectively). Over time, both treatments generally reduced the percentages of sites positive for the eight putative periodontopathic bacteria, although greater reductions were seen often for the SRP + CHX treatment group. Conclusions: The adjunctive use of the CHX chip resulted in a significant PD reduction and a clinical attachment gain compared to SRP alone. These results were concomitant with a significant benefit of SRP + CHX treatment on the subgingival microbiota