Subinhibitory concentrations of moxifloxacin decrease adhesion and biofilm formation of Stenotrophomonas maltophilia from cystic fibrosis.

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.

Effect of environmental factors on biofilm formation by clinical Stenotrophomonas maltophilia isolates.

The influence of environmental factors (temperature, aerobiosis-anaerobiosis, static-dynamic conditions, pH) was determined on biofilm formation by 51 S. maltophilia clinical isolates. The strains produced more biofilm at 32 degrees C than at 37 or 18 degrees C. Aerobic and 6% CO2 atmosphere yielded comparable biofilm amounts, higher than under anaerobic conditions. Biofilm production was not affected by static vs. agitated culture conditions. Biofilm production at pH 7.5 and 8.5 was comparable but significantly higher than at pH 5.5. The capacity of individual strains to form biofilm and thus contribute to the severity of some diseases is influenced by host traits and environmental conditions at the site of infection, and play an important role in the pathogenesis of biomaterial-related disease caused by S. maltophilia.

E-test method for detecting antibiotic synergy against Pseudomonas aeruginosa from neutropenic patients: a cost-effective approach.

The aim of this study was to evaluate the accuracy of E-test for the detection of synergy or antagonism of antibiotic combinations against Pseudomonas aeruginosa isolates from neutropenic patients. The activity of levofloxacin or grepafloxacin combined with ceftriaxone or cefotaxime against 20 P. aeruginosa clinical strains was assessed by checkerboard technique in comparison with results performed by E-test. The combination grepafloxacin + ceftriaxone appeared to be most effective (synergy, 55%) by checkerboard technique. The agreement between checkerboard and E-test results was 71.2%. Synergy was detected by checkerboard and E-test methods in 35 (43.8%) and 23 (31.3%) of 80 possible combinations, respectively. Antagonism was detected once (1.2%) by checkerboard method only. No major errors were recorded. E-test was preferable to checkerboard method for the total cost (reagent cost + cost of technologist time) (8,60 vs 21,80 euros/test, respectively). E-test appeared a promising alternative for testing antibiotic combinations although further testing should be performed to better refine this metodology.

In vitro activity of clarithromycin against intracellular Helicobacter pylori.

The in vitro intracellular effect of clarithromycin, amoxicillin, metronidazole, lansoprazole, and rifabutin, tested at concentrations corresponding to one times the MIC, two times the MIC, and four times the MIC, was evaluated against an invasive Helicobacter pylori strain. At four times the MIC, clarithromycin showed an early bactericidal effect within 4 h of incubation and, in determining the complete killing within a 16 h-incubation period, lansoprazole and rifabutin showed comparable activity, yielding bactericidal activities within 4 and 8 h of incubation, respectively. Amoxicillin and metronidazole showed bacteriostatic activity only.

Bacteriological and clinical follow-up of periodontal pockets during a topically applied 1% metronidazole-gel therapy in patients with adult periodontitis.

The aim of this study was to evaluate the clinical and bacteriological effects of the intrasulcular application of a 1% metronidazole-gel (repeated administrations outdistanced of 7 days weeks long) currently employed in dermatological practice, to observe if a lower concentration of the chemotherapic agent could be equally effective as the 25% formulation in improving the periodontal condition of nine patients with adult periodontitis. The results showed that this regimen can modify, at a statistically significant level, the clinical (Pocket Probing Depth, Gingival Bleeding Index and Plaque Index) and bacteriological (Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia and Veillonella parvula) parameters associated with adult periodontitis. The results are similar to those obtainable with a 25% Metronidazole-gel administered two times outdistanced by 7 days.

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 Ringer's 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.

Clinical significance of Actinobacillus actinomycetemcomitans in young individuals during orthodontic treatment. A 3-year longitudinal study.

The aim of the present study was: (1) to assess longitudinally the occurrence of Actinobacillus actinomycetemcomitans (Aa) in young subjects wearing fixed orthodontic appliances compared to matched appliance-free controls; (2) to determine whether the presence of the micro-organism at baseline could influence the periodontal status assessed 3 years later. 70 subjects, 27 male and 43 female, aged between 12 and 20 years participated in the study: 35 subjects under orthodontic treatment with fixed appliances for at least 6 months, and 35 appliance-free individuals matched for age and gender. All subjects were free of clinically demonstrable loss of attachment. They all received oral hygiene instructions 2x during the 2 months preceding the first clinical and microbiological examination. No subgingival instrumentation was performed between baseline and the 3-year examination. Clinical parameters included gingival bleeding index (GBI), pocket probing depth (PPD) and measurements of attachment level (AL). Statistically significant differences were reported regarding frequency of detection of Aa between both groups at each examination. The %s of orthodontic subjects infected with Aa at the baseline and at the 3-year examination were 86% and 80%, respectively, while the corresponding figures for control subjects were 16.6% and 26.6%. The frequency distribution of %s of Aa in the total anaerobic subgingival flora among control subjects remained fairly stable, whereas the proportion of orthodontic subjects yielding Aa at a concentration > or = 1.0% dropped significantly from 32% at baseline to 19% at the 3-year visit. Calculations of the relative risk for increasing GBI and PPD in both groups when Aa was present at baseline, revealed that the orthodontic subjects positive for Aa had a negligible relative risk of experiencing worse periodontal conditions compared to orthodontic patients where Aa was not detected at baseline. In contrast, control subjects initially infected with Aa presented with a risk for increased GBI 6.6x higher than that for subjects without Aa. In conclusion, the present study confirmed previous cross-sectional findings reporting that young individual with an integer periodontium wearing fixed orthodontic appliances harbor Aa with a statistically significant greater frequency than appliance-free matched controls. However, although orthodontic patients exhibited more inflammation, their deteriorated clinical conditions could not be accounted for by the sole presence of Aa in their sulci. In contrast, appliance-free young subjects initially infected with Aa had a higher risk of experiencing more gingival inflammation than subjects without the bacterium during a 3-year observation period.

In vitro antimicrobial susceptibility of periodontopathic Actinobacillus actinomycetemcomitans to roxithromycin and erythromycin.

The in vitro minimal inhibitory concentrations (MIC) and minimal bactericidal concentration (MBC) of roxithromycin and erythromycin against Actinobacillus actinomycetemcomitans were evaluated. Sixty-seven different A. actinomycetemcomitans isolated from periodontal pockets of 101 subjects with different forms of early-onset and adult periodontitis and three reference strains of A. actinomycetemcomitans (ATCC 29522, ATCC 29523, and NCTC 9710) were included in this study. Erythromycin showed poor in vitro activity against A. actinomycetemcomitans; roxithromycin, on the contrary, exhibited good in vitro activity. Moreover, roxithromycin showed the best in vitro antimicrobial activity against 17 serotype a and 12 serotype c subpopulations of A. actinomycetemcomitans; against 38 serotype b subpopulation of A. actinomycetemcomitans, roxithromycin was consistently active. Roxithromycin exhibited MBC values usually equal to, or one-fold higher than MIC values. All the MBC values of erythromycin were three- to four-fold higher than the respective MIC result. Since roxithromycin is characterized by high concentrations in serum and good penetration and diffusion into gingival tissue, it could be expected to pass into the gingival crevicular fluid at levels sufficiently high to inhibit A. actinomycetemcomitans in vivo. These data indicate that roxithromycin might be a potential candidate for therapeutic trials in patients with A. actinomycetemcomitans-associated periodontitis.

Frequency of detection of Actinobacillus actinomycetemcomitans in young patients during fixed orthodontic therapy.

The aim of the present study was to assess the occurrence of Aa in subgingival plaques from young subjects undergoing orthodontic treatment with fixed appliances; moreover we sought a possible relationship between the presence of Aa and the clinical conditions, also taking into consideration the different types of appliances, i.e., orthodontic bands or brackets.

Occurrence of Actinobacillus actinomycetemcomitans in patients wearing orthodontic appliances. A cross-sectional study.

The aim of the present study was to assess: (1) the occurrence of Actinobacillus actinomycetemcomitans (Aa) in subgingival plaque from young patients undergoing orthodontic treatment with fixed appliances; (2) a possible relationship between the presence of Aa and the clinical conditions; (3) a relation between the duration of orthodontic treatment and the microbiological and clinical parameters; (4) whether differences exist when taking into consideration the different type of appliances, i.e., bands or brackets. 34 subjects aged between 12 and 20 years participated in the study. Of these, 20 subjects had worn orthodontic appliances (test group), while the remaining 14 subjects served as matched control (control group). 4 to 8 sites in each patient were available for clinical and microbiological examination. Clinical parameters consisted of presence/absence of plaque and gingival bleeding index (GBI). Microbiological sampling was performed in the same sites as in the clinical examination. A statistically significant difference was present when comparing %s of GBI positive scores between teeth from the test group (57.5%) and teeth from the control group (25%). Plaque was present in 53% of test sites and 37% of control sites, but this difference was not statistically significant. Aa was detected from at least one site in 85% of test subjects and in 15% of the control subjects (p < 0.001). Among the subjects, 41% harboured Aa at a concentration between 0.1% and 1.0%, whereas another 40% yielded Aa at a concentration greater than 1.0%. Finally, a positive correlation was noted between the % of sites positive for Aa and the % of sites displaying a positive GBI score (r = 0.41; p < 0.005). No relation was found between the duration of orthodontic treatment and the microbiological or clinical parameters; neither were statistically significant differences found when we compared results from sites wearing bands or brackets. In conclusion, the present study showed that young subjects wearing orthodontic appliances harbour Aa with a remarkable frequency of detection, although plaque levels do not significantly differ from those of a matched control group.

Evaluation of Staf-Sistem 18-R for identification of staphylococcal clinical isolates to the species level.

The accuracy and efficiency of Staf-Sistem 18-R (Liofilchem s.r.l., Roseto degli Abruzzi, Teramo, Italy) were compared with those of conventional biochemical methods to identify 523 strains belonging to 16 different human Staphylococcus species. Overall, 491 strains (93.9%) were correctly identified (percentage of identification, > or = 90.0), with 28 (5.4%) requiring supplementary tests for complete identification. For 14 isolates (2.8%), the strains did not correspond to any key in the codebook and could not be identified by the manufacturer's computer service. Only 18 isolates (3.4%) were misidentified. The system is simple to use, is easy to handle, gives highly reproducible results, and is inexpensive. With the inclusion of more discriminating tests and adjustment in supplementary code numbers for some species, such as Staphylococcus lugdunensis and Staphylococcus schleiferi, Staf-Sistem 18-R is a suitable alternative for identification of human coagulase-positive and coagulase-negative Staphylococcus species in microbiological laboratories.

[Urinary tract infection in an ambulatory population: epidemiological analysis of the etiology and antibiotic resistance of isolated gram-negative strains]. / Infezioni al tratto urinario di una popolazione ambulatoriale: analisi epidemiologica sull'etiologia e sull'antibiotico-resistenza dei ceppi gram-negativi isolati.

15,892 urinocultures belonging to out-patients admitted to Chieti ULSS 04, from January '85 to December '89 were studied. Among the examined samples, the positive urinocultures were 4255 (26.8%) with a prevalence in the female sex (78.6%). During the year E. coli was the most frequently identified organism (55.8%) without significant changes. 25.7% was the isolation percentage of Morganella-Proteus-Providencia (MPP). In order to plan a right antibiotic-therapy the resistance of isolates to 19 chemo-antibiotics, during five years, was evaluated and compared.