[Show abstract][Hide abstract] ABSTRACT: The effect of different concentrations of 2-hydroxyethyl methacrylate (HEMA) was evaluated on biofilm formation and preformed biofilm of Streptococcus mitis, Streptococcus mutans and Streptococcus oralis, alone or combined to each other.
Twofold serial dilution of HEMA ranged from 12 to 0·75 mmol l(-1) was added to Streptococcal broth cultures and mature biofilms in 96-well-microtitre plates to evaluate bacterial biomass and cell viability. HEMA affected the Streptococcal population in a strain-specific way producing few significant effects. A reduction on biofilm formation and a detachment of preformed biofilm was recorded in Strep. mitis ATCC 6249, whereas in mixed cultures, the monomer expressed a general aggregative effect on mature biofilms. A reduction in cell viability was also recorded in an HEMA-concentration-dependent way in each experimental condition studied.
These results suggest that the HEMA prevalent effects are both the reduction of bacterial adhesion to a polystyrene surface and the increase in dead cells also characterized by an aggregative status.
Understanding the potential effect of HEMA, released from resin-based materials, on oral bacteria may furnish information for surveillance of the risk reduction in secondary caries via hindering biofilm generation.
Letters in Applied Microbiology 03/2011; 52(3):193-200. · 1.63 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Stenotrophomonas maltophilia 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 S. maltophilia 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 S. maltophilia to IB3-1 cell monolayers was also assessed by using fliI mutant derivative strains.
All S. maltophilia 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 S. maltophilia 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. S. maltophilia 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 P. aeruginosa PAO1 significantly increased S. maltophilia adhesiveness. Further, the presence of S. maltophilia negatively influenced P. aeruginosa PAO1 adhesiveness.
The main contribution of the present study is the finding that S. maltophilia 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 in vivo models which more closely mimic CF pulmonary tissues will certainly be needed to validate the relevance of our results.
[Show abstract][Hide abstract] ABSTRACT: Stenotrophomonas maltophilia is a pathogen that causes infections mainly in immunocompromised patients. Despite increased S. maltophilia isolation from respiratory specimens of patients with cystic fibrosis (CF), the real contribution of the microorganism to CF pathogenesis still needs to be clarified. The aim of the present study was to evaluate the pathogenic role of S. maltophilia in CF patients by using a model of acute respiratory infection in DBA/2 mice following a single exposure to aerosolized bacteria. The pulmonary bacterial load was stable until day 3 and then decreased significantly from day 3 through day 14, when the bacterial load became undetectable in all infected mice. Infection disseminated in most mice, although at a very low level. Severe effects (swollen lungs, large atelectasis, pleural adhesion, and hemorrhages) of lung pathology were observed on days 3, 7, and 14. The clearance of S. maltophilia observed in DBA/2 mouse lungs was clearly associated with an early and intense bronchial and alveolar inflammatory response, which is mediated primarily by neutrophils. Significantly higher levels of interleukin-1beta (IL-1beta), IL-6, IL-12, gamma interferon (IFN-gamma), tumor necrosis factor alpha (TNF-alpha), GROalpha/KC, MCP-1/JE, MCP-5, macrophage inflammatory protein 1alpha (MIP-1alpha), MIP-2, and TARC were observed in infected mice on day 1 with respect to controls. Excessive pulmonary infection and inflammation caused systemic effects, manifested by weight loss, and finally caused a high mortality rate. Taken together, our results show that S. maltophilia is not just a bystander in CF patients but has the potential to contribute to the inflammatory process that compromises respiratory function.
Infection and immunity 03/2010; 78(6):2466-76. · 4.21 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The use of locally delivered antibacterials containing chlorhexidine (CHX) was proposed to improve the effectiveness of non-surgical periodontal treatment. The present multicenter randomized study investigated the effects of a xanthan-based chlorhexidine (Xan-CHX) gel used as an adjunct to scaling and root planing (SRP) in the treatment of chronic periodontitis.
Ninety-eight systemically healthy subjects with moderate to advanced periodontitis were recruited in four centers (59 females and 39 males; aged 24 to 58 years). For each subject, two experimental sites located in two symmetric quadrants were chosen with probing depths (PD) >or=5 mm and positive for bleeding on probing (BOP). These two sites were randomized at the split-mouth level with one receiving a single SRP treatment and the other receiving a single SRP + Xan-CHX gel treatment. Supragingival plaque, modified gingival index, PD, clinical attachment level (CAL), and BOP were evaluated at baseline (prior to any treatment) and after 3 and 6 months. At the same times, subgingival microbiologic samples and gingival crevicular fluid (GCF) were collected for the analysis of total bacterial counts (TBCs), including the identification of eight putative periodontopathogens, and alkaline phosphatase (ALP) activity, respectively.
The Xan-CHX treatment group showed greater improvements compared to the SRP group for PD and CAL at 3 and 6 months (P <0.001). The differences in PD reduction between the treatments were 0.87 and 0.83 mm at 3 and 6 months, respectively (P <0.001); for CAL, these were 0.94 and 0.90 mm, respectively (P <0.001). Similar behavior was seen when the subgroup of pockets >or=7 mm was considered. The percentage of sites positive for BOP was similar between the treatments at each time point. For the comparisons between the treatment groups, no differences were seen in the TBCs and GCF ALP activity at baseline and 6 months; in contrast, slightly, but significantly, lower scores were recorded for the Xan-CHX treatment group at 3 months (P = 0.018 and P = 0.045, respectively). Moreover, greater reductions in the percentages of sites positive for the eight putative periodontopathic bacteria were generally seen for the Xan-CHX treatment group compared to SRP alone.
The adjunctive use of Xan-CHX gel promoted greater PD reductions and CAL gains compared to SRP alone. These results were concomitant with better microbiologic and biochemical outcomes when Xan-CHX gel use was added to SRP, particularly up to 3 months after treatment.
Journal of Periodontology 09/2009; 80(9):1479-92. · 2.40 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Stenotrophomonas maltophilia is an emerging nosocomial bacterial pathogen that is currently isolated with increasing frequency from the airways of cystic fibrosis (CF) patients. In this study the effect of subinhibitory concentrations (subMICs) of moxifloxacin on adhesion, biofilm formation and cell-surface hydrophobicity of two strains of S. maltophilia isolated from CF patients were evaluated. Adhesion and biofilm formation assays were carried out on polystyrene and quantified by colony counts. Cell-surface hydrophobicity was determined by a test for adhesion to n-hexadecane. Moxifloxacin at 0.03x and 0.06x MIC caused a significant decrease in adhesion and biofilm formation by both strains tested. A significant reduction in cell-surface hydrophobicity following exposure to subMICs of moxifloxacin was observed for one strain only. The results of the present study provide an additional rationale for the use of moxifloxacin in CF patients and more generally in biofilm-related infections involving S. maltophilia.
Journal of Medical Microbiology 09/2009; 59(Pt 1):76-81. · 2.30 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Coagulase-negative staphylococci are known to be frequently isolated from clinical specimens and represent the most common cause of bacteraemias in hospitalized patients. Particularly, venous catheter-related bloodstream infections are often due to non-aureus staphylococci. These are opportunistic pathogens in immunocompromised hosts and may behave as reservoirs of antibiotic resistance determinants.(1).
Journal of clinical pathology 07/2009; 62(10):957-8. · 2.43 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The primary goal of periodontal therapy is the removal of supra and subgingival bacterial deposits by mechanical debridement consisting in scaling and root-planing (SRP) using manual or power-driven instruments. The complete removal of bacteria and their toxins from periodontal pockets is not always achieved with conventional mechanical treatment. The use of lasers as an adjunctive therapy for periodontal disease may improve tissue healing by bactericidal and detoxification effects. The aim of this study was to compare the effectiveness of Diode laser used as adjunctive therapy of SRP to that of SRP alone for non surgical periodontal treatment in patients with chronic periodontitis. Nineteen pairs of teeth with untreated chronic periodontitis were selected in 13 patients and randomly treated by SRP alone (control group) or by SRP + laser irradiation (test group). Clinical measurements (PPD, CAL, BOP, GI, PI) were performed before treatment at baseline (T0) and at T1 (after 4 weeks), T2 (8 weeks), T3 (12 weeks), T4 (6 months). Subgingival plaque samples were taken at baseline and after treatment and examined for 8 periopathogens bacteria using PCR technique. The present study showed that the additional treatment with diode laser may lead to a slightly improvement of clinical parameters, whereas no significant differences between test and control group in reduction of periodontopathogens were found.
The New Microbiologica: official journal of the Italian Society for Medical Virology (SIVIM) 11/2008; 31(4):513-8. · 1.67 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We describe the case of a graft versus host disease (GvHD) patient, in whom Hafnia alvei was cultured as a single organism, and at high bacterial counts from stool samples, from the onset of the disease until its resolution. This case is a further example of the contentious role of this species in causing human intestinal disease. Furthermore, it focuses on enteric damage by GvHD as a risk factor for acquiring H. alvei colonization, and probably infection.
Journal of Medical Microbiology 10/2008; 57(Pt 9):1167-9. · 2.30 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We tested 40 clinical Stenotrophomonas maltophilia strains to investigate the possible correlation between adherence to and formation of biofilm on polystyrene, and cell surface properties such as hydrophobicity and motility. Most of the strains were able to adhere and form biofilm, although striking differences were observed. Eleven (27.5%) of the strains were hydrophobic, with hydrophobicity greatly increasing as S. maltophilia attached to the substratum. A positive correlation was observed between hydrophobicity and levels of both adhesion and biofilm formation. Most of the isolates showed swimming and twitching motility. A highly significant negative correlation was observed between swimming motility and level of hydrophobicity. Hydrophobicity is thus a significant determinant of adhesion and biofilm formation on polystyrene surfaces in S. maltophilia.
[Show abstract][Hide abstract] ABSTRACT: This case report is a case history of a femoral prosthesis infection caused by Rhodotorula mucilaginosa in a human immunodeficiency virus patient. Though the pathogenicity of this organism for bone tissue has been previously reported, this is the first reported case of an orthopedic prosthesis infection by this species of the genus Rhodotorula.
Journal of clinical microbiology 09/2008; 46(10):3544-5. · 4.16 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Microbial penetration inside an implant's internal cavity results in a bacterial reservoir that has been associated with an area of inflamed connective tissue facing the fixture-abutment junction. The aim of the present clinical trial was to evaluate the effectiveness of a 1% chlorhexidine gel on the internal bacterial contamination of implants with screw-retained abutments.
Thirty subjects (age range: 27.3 to 54.2 years) underwent single implant restoration. Three months after prosthodontic restoration, the modified sulcus bleeding index, modified plaque index, full-mouth plaque score, and full-mouth bleeding score were recorded. Microbiologic samples were also collected from the internal part of each fixture. Subjects were then divided into two equal groups: control and test groups (CG and TG, respectively). The CG had the abutment screwed and the crown cemented without any further intervention. Conversely, the TG had the internal part of the fixture filled with a 1% chlorhexidine gel before the abutment placement and screw tightening. Six months later, microbiologic and clinical procedures were repeated in both groups. Total bacterial count and multiplex polymerase chain analysis were performed to detect specific pathogens.
Clinical parameters remained stable throughout the study. From baseline to the 6-month examination, the total bacterial counts underwent a significant reduction in the TG (P<0.05). Detection of the single pathogen species did not show any significant differences. However, periopathogens were detected more frequently in the CG.
The application of a 1% chlorhexidine gel seemed to be an effective method to reduce bacterial colonization of the implant cavity over a 6-month period.
Journal of Periodontology 08/2008; 79(8):1419-25. · 2.40 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: 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-by-site, 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.
The New Microbiologica: official journal of the Italian Society for Medical Virology (SIVIM) 08/2008; 31(3):383-91. · 1.67 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Genitourinary infections caused by non-Candida yeasts are uncommon, and especially due to Saccharomyces cerevisiae. We describe the cases of two adult females with vulvovaginal infections caused by itraconazole-resistant S. cerevisiae who made a full recovery after oral fluconazole therapy. We also provide a concise review of recently published studies on
[Show abstract][Hide abstract] ABSTRACT: Invasive aspergillosis (IA) is the leading direct or contributory cause of death in patients with haematological malignancies. Early diagnosis remains difficult and often elusive due the heterogeneity of clinical presentations and the low sensitivity of both histological examination and cultures of specimens obtained from patients at risk. We report two cases of IA, both of which lacked both histological and cultural evidence of IA from pulmonary specimens. In both patients, detection of galactomannan (GM) by enzyme immunoassay (EIA) on pulmonary tissue homogenates led to the diagnosis of IA, which was confirmed by Aspergillus DNA (real time PCR). In conclusion, we provide preliminary evidence that lung homogenates may be prepared for GM EIA assays, which may contribute to quick diagnosis of IA on otherwise negative samples. We feel that our results open up the opportunity of a prospective and comparative evaluation of this diagnostic technique.
European Journal of Clinical Microbiology 06/2008; 27(5):391-4. · 3.02 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: To assess the ability of Listeria monocytogenes to form biofilm on different food-contact surfaces with regard to different temperatures, cellular hydrophobicity and motility.
Forty-four L. monocytogenes strains from food and food environment were tested for biofilm formation by crystal violet staining. Biofilm levels were significantly higher on glass at 4, 12 and 22 degrees C, as compared with polystyrene and stainless steel. At 37 degrees C, L. monocytogenes produced biofilm at significantly higher levels on glass and stainless steel, as compared with polystyrene. Hydrophobicity was significantly (P < 0.05) higher at 37 degrees C than at 4, 12 and 22 degrees C. Thirty (68.2%) of 44 strains tested showed swimming at 22 degrees C and 4 (9.1%) of those were also motile at 12 degrees C. No correlation was observed between swimming and biofilm production.
L. monocytogenes can adhere to and form biofilms on food-processing surfaces. Biofilm formation is significantly influenced by temperature, probably modifying cell surface hydrophobicity. SIGNIFICANCE AND IMPACTS OF THE STUDY: Biofilm formation creates major problems in the food industry because it may represent an important source of food contamination. Our results are therefore important in finding ways to prevent contamination because they contribute to a better understanding on how L. monocytogenes can establish biofilms in food industry and therefore survive in the processing environment.
Journal of Applied Microbiology 06/2008; 104(6):1552-61. · 2.20 Impact Factor