Giovanni Catamo

Site-specific Subgingival Colonization by Actinobacillus actinomycetemcomitans in Orthodontic Patients.

A high prevalence of Actinobacillus actinomycetemcomitans (Aa) in subgingival plaque in patients for orthodontia already has been observed. The present study had the following aims: 1) to ascertain a direct relationship between the orthodontic appliance placement and the subgingival colonization by Aa, and 2) to determine whether the Aa growth specifically occurred on teeth with braces attached or whether the presence of orthodontic appliances could also cause the isolation of Aa in teeth free from therapeutic appliances. Twenty-four young systemically and periodontally healthy subjects with malaligned and crowded teeth in the anterior sextants of both dental arches participated in this study. After 1 session of ultrasonic scaling with oral hygiene instructions during the first experimental session, the mesiobuccal sites of the first molars and the distobuccal sites of the lateral incisors in both dental arches in each participant were subjected to clinical and microbiologic examination for the recovery of Aa. Clinical examination consisted of recording the presence of plaque and the examination of gingival bleeding on probing and probing depth. Microbiologic sampling was obtained with the insertion of 3 sterile paper points at the deepest part of each gingival sulcus. Altogether, 192 periodontal sites were examined. After the examinations, the patients received fixed orthodontic appliances in only 1 dental arch (test sites) and the other one was left free from appliances (control sites). Clinical examination and microbiologic sampling were repeated in the same experimental test and control sites after 4, 8, and 12 weeks. At the 12-week session, the orthodontic appliance was removed from the test arch, and, 4 weeks later, a further clinical and microbiologic examination was performed. The results showed that, during the period with orthodontic appliances, the presence of plaque scores and the gingival bleeding on probing scores were increased significantly and that Aa, initially absent from all but 1 subject, was isolated in 19 and 20 subjects after 4 and 8 weeks, respectively. Furthermore, no gingival sites from the control teeth (free from Aa colonization at baseline) showed positive results for the sought-after bacterium throughout the entire length of the study. It was concluded that the placement of orthodontic appliances promotes the subgingival growth of Aa; this specific microbial change is specifically restricted to subgingival plaque from orthodontic appliance-bearing teeth. The presence of orthodontic bands and brackets therefore cannot affect the microbiologic condition of the whole mouth.

Bacteriologic Evaluation of the Effect of Nd:YAG Laser Irradiation in Experimental Infected Root Canals

The aim of this study was to evaluate the efficacy of the Pumped Diodium-Nd:YAG laser in sterilizing contaminated root canals. After hand instrumentation, 30 teeth were inoculated with Actinomyces naeslundii CH-12 and 30 teeth with Pseudomonas aeruginosa ATCC 27853 and incubated for 24 h. The teeth were divided into three subgroups: subgroup A received no treatment; subgroup B was irradiated with laser (5 Hz for 15 s or 10 Hz for 15 s); and subgroup C was irrigated with 5.25% NaOCl. The number of viable bacteria in each group was evaluated by using the surface-spread plate technique. The results indicated an average of 34.0% decrease in colony-forming units for A. naeslundii CH-12 and 15.7% for P. aeruginosa ATCC 27853 with the 5 Hz/15 s laser treatment, and for the 10 Hz laser frequency, a decrease of the 77.4% for A. naeslundii CH-12 and 85.8% for P. aeruginosa ATCC 27853. No bacteria were detected in the canals treated with 5.25% NaOCl. The results show an antibacterial effect of the Pumped Diodium Nd:YAG laser, depending on the radiation frequency. However, 5.25% NaOCl was more effective than either laser application.

Diagnosis in periodontology: a further aid through microbiological tests.

Most of the current knowledge of the complex microbiology of oral biofilms, which initiates and maintains periodontal lesions, has been facilitated by the introduction of molecular techniques. Several studies exalt the high sensitivity and specificity of molecular tests in the detection and quantification of periodontal pathogens. Although they have large a diffusion, the old method of bacterial culture remains nowadays the gold standard when determining the utility of a new microbial test. Moreover, cultures have the important advantage of allowing an antibiotic sensitivity test and this is much more important during the treatment of patients with aggressive periodontitis.

Comparison of Etest, agar dilution, broth microdilution and disk diffusion methods for testing in vitro activity of levofloxacin against Staphylococcus spp. isolated from neutropenic cancer patients

The susceptibility to levofloxacin of 194 consecutive staphylococcal (45 Staphylococcus aureus and 149 coagulase-negative staphylococci) isolates from neutropenic patients was determined by Etest and the results compared with those obtained using NCCLS-methods (broth microdilution, agar dilution and disk diffusion). Overall agreement at +/- 1log(2) dilution for Etest compared with broth microdilution and agar dilution was 99.0 and 83.5%, respectively. The Etest category agreement with broth microdilution and disk diffusion was 95.9 and 89.7%, respectively. Comparison of categories with Etest and agar dilution method gave only 67.0% absolute categorical agreement, with 29.9% minor errors and 10.7% major errors. No very major errors occurred by the four methods tested. Our results show that Etest is a valid alternative to the reference NCCLS-methods for monitoring the clinical usefulness of levofloxacin against staphylococci isolates from neutropenic patients.

Microbiological and biochemical effectiveness of an antiseptic gel on the bacterial contamination of the inner space of dental implants: a 3-month human longitudinal study.

Microbial penetration inside the implants internal cavity produces a bacterial reservoir that is associated with an area of inflamed connective tissue facing the fixture-abutment junction. The aim of this clinical trial is to evaluate the effectiveness of a 1% chlorhexidine gel on the internal bacterial contamination of implants with screw-retained abutments and on the level of AST secreted in peri-implant crevicular fluid. Twenty-five patients (aged 29 to 58 years) each received one implant. Three months after the end of the restorative treatment, and immediately after a clinical and radiographic examination and the abutment removal, microbiological samples were obtained from the internal part of each fixture and biochemical samples were collected by peri-implant sulci. The patients were then divided into two groups: the control (CG; n=10) and test (TG; n=15) groups. The CG had the abutment screwed into place and the crown cemented without any further intervention. In contrast, before the abutment placement and screw tightening, the TG had the internal part of the fixture filled with a 1% chlorhexidine gel. Three months later, the same clinical, microbiological and biochemical procedures were repeated in both groups. Total bacterial count, specific pathogens and AST activity were detected. The clinical parameters remained stable throughout the study. From baseline to the 3-month examination, the total bacterial counts underwent a significant reduction only in the TG. In contrast, the AST activity showed a significant increase in the CG. The administration of a 1% chlorhexidine gel appears to be an effective method for the reduction of bacterial colonization of the implant cavity and for safeguarding the health status of peri-implant tissue over a 3-month administration period.

Laboratory and clinical comparison of preservation media and transport conditions for survival of Actinobacillus actinomycetemcomitans

The capacity of clinical isolates and type strains of Actinobacillus actinomycetemcomitans to survive in a new transport medium (AaTM), phosphate-buffered saline (PBS) and Ringers solution (RS) was evaluated. The effects of exposure to air, transportation time and temperature on viability were also studied. In addition, the culture of A. actinomycetemcomitans from subgingival plaque of patients with different forms of periodontitis was quantified. The results following storage in AaTM, PBS and RS showed that A. actinomycetemcomitans survived better in AaTM than in PBS or RS when transportation times exceeded 20-22 h, and that survival was enhanced by storage at below 12 degrees C. Serotype b strains of A. actinomycetemcomitans were able to survive better than either serotype a or c. In the clinical study the optimal transportation conditions for subgingival plaque containing A. actinomycetemcomitans were AaTM at a temperature of 8 degrees C for 24 h under anaerobic conditions. These conditions resulted in a high survival and isolation rate for A. actinomycetemcomitans without inhibition of the other periodontopathic bacteria isolated from deep periodontal pockets. These findings have practical implications for future multicentre clinical trials in which the transportation of oral specimens over relatively long distances and at different ambient temperatures during various periods of the year are required.

Comparative in vitro Activity of Levofloxacin and Ciprofloxacin against Bacterial Isolates from Neutropenic Patients

Background: Novel fluoroquinolones have been recently introduced in the management of neutropenic patients because of their increased activity against gram-positive and gram-negative micro-organisms. Methods: The activities of levofloxacin and ciprofloxacin were determined by the E test against 223 bacterial isolates from patients with haematological malignancies. Results: In general, the activity of levofloxacin was comparable to that of ciprofloxacin. Levofloxacin was somewhat more active against methicillin-resistant Staphylococcus aureus isolates. All methicillin-susceptible S. aureus isolates were inhibited by ciprofloxacin and levofloxacin at a concentration of ≤0.5 and ≤0.25 µg/ml, respectively. Among gram-negative isolates tested, levofloxacin was significantly (p < 0.001) more active than ciprofloxacin against Stenotrophomonas maltophilia, inhibiting 68 and 53% of these isolates, respectively. Conclusions: Levofloxacin was not superior to ciprofloxacin in its overall antibacterial activity, although small differences between these agents were seen depending on the species tested. In particular, our data suggested that levofloxacin may potentially be used for the management of S. maltophilia infections in neutropenic patients.

In vitro Staphylococcus epidermidis Growth in Some Viscoelastic Substances Containing Sodium Hyaluronate

The aim of our study was to verify the in vitro growth of Staphylococcus epidermidis in various dilutions of some viscoelastic substances containing hyaluronic acid (Healon® and Healon GV, IAL®, BiolonTM). Serial twofold dilutions of each sterile viscoelastic substance, prepared so as to obtain a final concentration ranging from 50 to 0.78% of the product in sterile saline solution (0.85% NaCl), were taken out with a pipette that delivered 1.0 ml/tube. One hundred microliters of the S. epidermidis inocula, used for the evaluation of the positive control of the test organism, was dispensed into each tube. After 24 h of aerobic incubation at 37 °C, 100 μl of sample was taken out from each tube and plated into the specific medium for the growth of the test organism. After 24 h of incubation at 37 °C, these agar plates were examined and the colony-forming unit count of the test organism was compared to the corresponding total colony count, acting as a positive control, in order to determine the quantitative variation of the test organism grown in the presence of the viscoelastic compounds. For the lowest dilutions (from 1: 2 to 1: 8) statistically significant bacterial growth was detected in all tested viscoelastic substances. For the highest dilutions (1: 64 and 1: 128) Biolon and Healon GV showed a significant inhibition of S. epidermidis growth. A significant inhibition was also observed in the highest dilution (1: 128) of Healon. In every dilution of IAL a statistically significant increase in bacterial growth was observed. It remains to be carefully considered whether S. epidermidis, accidentally penetrating the eye via the intraocular lens, could find a culture medium in a small amount of sodium hyaluronate left in the capsular bag behind the optic.