Effectiveness of ozone against endodontopathogenic microorganisms in a root canal biofilm model.

AIM: To assess the antimicrobial efficacy of aqueous (1.25-20 microg mL(-1)) and gaseous ozone (1-53 g m(-3)) as an alternative antiseptic against endodontic pathogens in suspension and a biofilm model. METHODOLOGY: Enterococcus faecalis, Candida albicans, Peptostreptococcus micros and Pseudomonas aeruginosa were grown in planctonic culture or in mono-species biofilms in root canals for 3 weeks. Cultures were exposed to ozone, sodium hypochlorite (NaOCl; 5.25%, 2.25%), chlorhexidine digluconate (CHX; 2%), hydrogen peroxide (H(2)O(2); 3%) and phosphate buffered saline (control) for 1 min and the remaining colony forming units counted. Ozone gas was applied to the biofilms in two experimental settings, resembling canal areas either difficult (setting 1) or easy (setting 2) to reach. Time-course experiments up to 10 min were included. To compare the tested samples, data were analysed by one-way anova. RESULTS: Concentrations of gaseous ozone down to 1 g m(-3) almost and aqueous ozone down to 5 microg mL(-1) completely eliminated the suspended microorganisms as did NaOCl and CHX. Hydrogen peroxide and lower aqueous ozone concentrations were less effective. Aqueous and gaseous ozone were dose- and strain-dependently effective against the biofilm microorganisms. Total elimination was achieved by high-concentrated ozone gas (setting 2) and by NaOCl after 1 min or a lower gas concentration (4 g m(-3)) after at least 2.5 min. High-concentrated aqueous ozone (20 microg mL(-1)) and CHX almost completely eliminated the biofilm cells, whilst H(2)O(2) was less effective. CONCLUSION: High-concentrated gaseous and aqueous ozone was dose-, strain- and time-dependently effective against the tested microorganisms in suspension and the biofilm test model.

Bacteriobilia in percutaneous transhepatic biliary drainage: occurrence over time and clinical sequelae. A prospective observational study.

BACKGROUND: In the diagnosis and treatment of biliary disorders, establishing percutaneous transhepatic biliary drainage (PTBD) is an invasive procedure that can potentially lead to infectious complications in both the short and long-term. We therefore prospectively analysed the time course and spectrum of biliary bacteria in patients undergoing PTBD. METHODS: Forty-nine patients (19 F, 30 M; mean age 64 years) with malignant (65%) or benign (35%) biliary disorders were included, 20 of whom had a newly established PTBD (group A), while the remaining 29 had already had their PTBD in situ (group B) for a mean of 8 months. Bacteriological analyses of bile and blood were carried out, and clinical symptoms and laboratory values were obtained. RESULTS: Biliary bacteria were found in 60% of cases during the initial PTBD placement, and 24 h later this rate had already increased to 85%; two or more microorganisms were found in 40% initially and in 70% after a few days. At later PTBD exchanges, bacteriobilia was found in 100%, with all patients harbouring multiple organisms. Whereas the initial spectrum was mixed, Escherichia coli and enterococci (97% each), Klebsiella (73%) and Bacteroides species (37%) later predominated; Candida increased initially from 15% to 80%, but later decreased to 30%. Clinical signs of cholangitis were observed in 30% initially (no sepsis), but decreased to 6% at later exchanges. CONCLUSIONS: Bacteriobilia is initially a frequent, and later a regular, event in PTBD; however, clinically significant complications are rare during the long-term course and limited to the initial, more invasive, phase of PTBD. A knowledge of the bacterial spectrum is important for selecting appropriate antibiotic coverage if complications arise and/or major interventions such as surgery are planned.

Fecal bacterial activity in symptomatic carbohydrate malabsorption: effect on the fecal short-chain fatty acid ratio.

BACKGROUND: It is still not clear why only some patients with carbohydrate malabsorption experience symptoms. In a previous study on healthy fructose malabsorbers an increased degradation of fructose in anaerobic fecal cultures from symptomatic malabsorbers was found, indicating increased bacterial activity. In the present study, the same investigation was repeated in patients with nonspecific abdominal complaints and fructose malabsorption. Moreover fecal short-chain fatty acids (SCFA), products of colonic bacterial fermentation of carbohydrates were measured. PATIENTS AND METHODS: A standard quantity of fructose (500 mg) was added to anaerobic fecal cultures from 25 patients (nine men, 16 women; median of age 53 years, range 36-69 years). The fructose degradation rate was assessed using photometry, and interpreted as representing bacterial activity in the colon. In 14 of the patients, SCFA levels were also measured using chromatography on a capillary column. RESULTS: 10 of the 25 patients had a history of symptoms after ingesting fructose-containing foods, and also showed symptoms during the test; 6 patients had symptoms either in their history or during the test; and the remaining 9 were free of symptoms. There were no differences in the H2 increase. The fructose degradation rate was higher in symptomatic malabsorbers (255 mg vs. 217 mg), but the difference was not significant. However, there was a strong inverse correlation between this bacterial activity and the acetate level, with r = -0.822 (P = 0.000) and r = -0.868 (P = 0.000) in the rank correlation. The correlation for propionate was r = 0.479 (P = 0.083), and that for butyrate was r = 0.599 (P = 0.024). CONCLUSIONS: This study failed to confirm a significant correlation between fecal bacterial activity and the occurrence of symptoms in patients with fructose malabsorption. However, the interesting correlation with the SCFA raises questions regarding possible connections between colonic bacteria, carbohydrate malabsorption, and the beneficial effect of this pattern of SCFA in several colonic diseases.

Failure of an automated blood culture system to detect nonfermentative gram-negative bacteria.

During a 1-year study we observed that both aerobic and anaerobic blood culture bottles from patients were negative by the BacT/Alert system during a 7-day incubation period. However, upon subcultivation of negative bottles, growth of Pseudomonas aeruginosa was detectable. In an attempt to explain this observation, aerobic BacT/Alert Fan bottles were seeded with a defined inoculum (0.5 McFarland standard; 1 ml) of Escherichia coli, Klebsiella pneumoniae, Serratia marcescens, P. aeruginosa, Stenotrophomonas maltophilia, or Acinetobacter baumannii. Half of the inoculated bottles were loaded into the BacT/Alert system immediately, and the remainder were preincubated for 4, 8, 16, and 24 h at 36 degrees C. With preincubation all bottles seeded with the Enterobacteriaceae signaled positive during the next 1.5 h. Organisms in bottles seeded with the nonfermentative species P. aeruginosa and A. baumannii remained undetected by the BacT/Alert system for 7 days. S. maltophilia was detected if the preincubation time was equal or less than 8 h. Without preincubation all bottles seeded with the Enterobacteriaceae or nonfermentative species signaled positive. Since nonfermentative species seem to enter a state of bacteriostasis within the preincubation period, we reasoned that an unknown factor is consumed. Accordingly, a smaller inoculum should allow the detection of nonfermentative species, even after preincubation, and serial dilutions of P. aeruginosa were detected in preincubated bottles. In this case preincubated bottles signaled positive faster than bottles without preincubation. We conclude that all bottles from clinical settings should be subcultured prior to loading to avoid false negatives. An alternative may be preincubation at room temperature.