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PubMed1990

Effect of root debridement on the elimination of Actinobacillus actinomycetemcomitans and Bacteroides gingivalis from periodontal pockets.

The aims of this 6-month longitudinal study were: (1) to investigate to what extent root debridement of pockets in adult periodontitis will reduce the subgingival presence of Actinobacillus actinomycetemcomitans, Bacteroides gingivalis and some other bacterial groups; (2) to relate the microbiological results following debridement to clinical measurements of healing. 16 patients and a total of 111 periodontally involved sites with probing depth greater than or equal to 6 mm served for the study. Duplicate subgingival microbial samples and duplicate clinical recordings were obtained 1 week apart at baseline and at 6 months following supra- and subgingival debridement. The results demonstrated reductions of the mean total viable counts and reductions of the mean counts of several of the cultured groups of micro-organisms coupled with significant improvements of mean clinical measurements. B. gingivalis was eliminated from a majority of infected subgingival sites. A. actinomycetemcomitans, on the other hand, still remained after therapy in a high proportion of sites initially infected with this microorganism. Subgingival persistence of A. actinomycetemcomitans appeared to be associated with a reduced healing response following debridement. Further studies are needed to clarify why A. actinomycetemcomitans is poorly eliminated following debridement. Also, the long-term clinical significance of the subgingival perseverance of A. actinomycetemcomitans needs to be elucidated.

Actinobacillus↗
PubMed2001

Relationship of cigarette smoking to the subgingival microbiota.

BACKGROUND: The relationship of cigarette smoking to the composition of the subgingival microbiota is not clear. Some studies indicated higher levels of certain species in smokers, while other studies failed to detect differences in the microbiota between subjects with different smoking histories. Thus, the purpose of the present investigation was to examine the prevalence, proportions and levels of the subgingival species in adult subjects who were current, past or never smokers. METHOD: 272 adult subjects ranging in age from 20-86 years with at least 20 teeth were recruited for study. Smoking history was obtained using a questionnaire. Clinical measures were taken at 6 sites per tooth at all teeth excluding third molars at a baseline visit. Subgingival plaque samples were taken from the mesial surface of all teeth excluding third molars in each subject at baseline and assayed individually for counts of 29 subgingival species using checkerboard DNA-DNA hybridization. Subjects were subset according to smoking history into never (n=124), past (n=98) and current smokers (n=50). Uni-variate and multi-variate analyses were used to seek associations between smoking category and the counts, proportions and prevalence of subgingival species. RESULTS: Greater differences were observed for the prevalence (% of sites colonized) of the test species in the 3 smoking groups than were observed for counts or proportions of total counts. Members of the orange and red complexes including E. nodatum, F. nucleatum ss vincentii, P. intermedia, P. micros, P. nigrescens, B. forsythus, P. gingivalis and T. denticola were significantly more prevalent in current smokers than in the other 2 groups. The difference in prevalence between smokers and non-smokers was due to greater colonization at sites with pocket depth <4 mm. Stepwise multiple linear regression analysis indicated that combinations of the prevalence of 5 microbial species and pack years accounted for 44% of the variance for mean pocket depth (p<0.000001), while the prevalence of 3 microbial taxa along with age, pack years, current smoking and gender accounted for 31% of the variance in mean attachment level (p<0.000001). The difference in prevalence between current and never smokers of all members of the red complex and 8 of 12 members of the orange complex was significantly greater in the maxilla than in the mandible. CONCLUSIONS: The major difference between the subgingival microbiota in subjects with different smoking history was in the prevalence of species rather than counts or proportions. The greater extent of colonization in smokers appeared to be due to greater colonization at pocket depths <4 mm. Differences in colonization patterns between current and never smokers were greater in the maxilla than in the mandible.

Adult↗
PubMed2005

Development of a quantitative real-time PCR method for estimation of the total number of Vibrio parahaemolyticus in contaminated shellfish and seawater.

A real-time PCR method targeting the toxR gene of Vibrio parahaemolyticus was developed to quantify the number of V. parahaemolyticus cells, including those of both the hemolysin-producing and nonproducing strains. The specificity of the primer and probe set was confirmed using 25 strains of V. parahaemolyticus and 30 strains of other microbial species. We determined the threshold cycle number using the real-time PCR and the number of V. parahaemolyticus cells by plate count using serially diluted pure culture and developed a standard curve for quantification. Standard curves for V. parahaemolyticus in seawater and seafood were established using artificially inoculated samples. The threshold cycle number and the number of V. parahaemolyticus cells were correlated with 10(1) to 10(7) CFU/ml in pure culture, seawater, and shellfish homogenate. The real-time PCR method developed in this study was compared with the most-probable-number method in seafood samples that were naturally contaminated. The differences in the number of V. parahaemolyticus cells as determined by the culture method and the PCR method were less than 10-fold.

Animals↗
PubMed1992

Microbiological evaluation of malted wheat, chickpea, and weaning food based on them.

The changes in the microbial load during steeping, germination, drying, kilning, and debranning of wheat and chickpea were studied, and the microflora of a weaning food formulation based on 48-hours germinated wheat and 24-hours germinated chickpea was also assayed. Total bacterial count (TBC) of control wheat and chickpea were 5 x 10(4)/g and 110 x 10(4)/g, respectively. The microbial load increased 9000-fold in wheat on 48-hours germination of wheat and 870-fold on 24-hours of germination of chickpea. The microbial counts decreased substantially on drying, kilning, and debranning, and the TBC of wheat and chickpea malt flours were 3 x 10(4)/g and 9 x 10(4)/g, respectively. Some of the spoilage microflora of health significance, viz. coliforms, E. coli, Streptococci, Staphylococci, yeast, and mould were assayed in raw materials and in the weaning foods based on malting (MWF), popping (PWF), and roller drying (RDF) of wheat and chickpea. The levels of these spoilage microflora were considerably high in raw materials and also in uncooked weaning foods, the load being high in MWF, moderate in PWF and low in RDF. Cooking the weaning foods slurry for 5 minutes at about 95 degrees C reduced the TBC and other spoilage microflora to safe limits, and counts were well within the prescribed values for the cereal-based weaning foods.

Colony Count, Microbial↗
PubMed2006

Presence and growth of naturalized Escherichia coli in temperate soils from Lake Superior watersheds.

The presence of Escherichia coli in water is used as an indicator of fecal contamination, but recent reports indicate that soil populations can also be detected in tropical, subtropical, and some temperate environments. In this study, we report that viable E. coli populations were repeatedly isolated from northern temperate soils in three Lake Superior watersheds from October 2003 to October 2004. Seasonal variation in the population density of soilborne E. coli was observed; the greatest cell densities, up to 3 x 10(3) CFU/g soil, were found in the summer to fall (June to October), and the lowest numbers, < or =1 CFU/g soil, occurred during the winter to spring months (February to May). Horizontal, fluorophore-enhanced repetitive extragenic palindromic PCR (HFERP) DNA fingerprint analyses indicated that identical soilborne E. coli genotypes, those with > or =92% similarity values, overwintered in frozen soil and were present over time. Soilborne E. coli strains had HFERP DNA fingerprints that were unique to specific soils and locations, suggesting that these E. coli strains became naturalized, autochthonous members of the soil microbial community. In laboratory studies, naturalized E. coli strains had the ability to grow and replicate to high cell densities, up to 4.2 x 10(5) CFU/g soil, in nonsterile soils when incubated at 30 or 37 degrees C and survived longer than 1 month when soil temperatures were < or =25 degrees C. To our knowledge, this is the first report of the growth of naturalized E. coli in nonsterile, nonamended soils. The presence of significant populations of naturalized populations of E. coli in temperate soils may confound the use of this bacterium as an indicator of fecal contamination.

Climate↗
PubMedDate not supplied

Real-time determination of microbial activity of pasteurized fluid milk using a novel microrespirometer method.

The effectiveness of the rapid CO2 evolution rate (CER) method was evaluated by using a novel noninstrumental microrespirometer to determine the microbial activity of pasteurized milk and comparing it with traditional culturing methods in homogeneous milk samples. Three different kinds of milk (skim, 1% fat, and whole) stored at 2 temperatures (4 degrees and 7 degrees C) were measured daily for CER, aerobic plate count (APC), and psychrotrophic bacterial count. The mean initial rates of CO2 evolution for all 3 samples stored at the 2 temperatures ranged from 3.42 to 3.71 microL/h/mL and increased to 29 microL/h/mL and above on the final day of the experiment. Regression analysis showed a high correlation (R = 0.98-0.99) between the APC and CER results in combined milk samples. A cut-off value of CER (25 microL/h/mL) for milk spoilage at refrigeration temperatures was identified. The real-time CER method shows promise as a potential alternative to the traditional culture method.

Animals↗
PubMed1991

Quantification of microbial populations associated with the manufacture of vacuum-packaged, smoked vienna sausages.

Sources of contamination of vacuum-packaged vienna sausages by spoilage microorganisms were examined in a meat-processing plant. Microbial numbers present in the environment, on working surfaces and workers' hands and aprons were quantified by plate counting on selective media. Product line samples were taken at critical control points in the manufacturing process and analysed before and after preliminary incubation of vacuum-packaged samples at 25 degrees C for 24 h. In all samples the numbers of aerobic bacteria, Enterobacteriaceae, lactic acid bacteria and yeasts were determined by standard procedures. Contamination of sausage surfaces by lactic acid bacteria occurred as a result of the manufacturing and handling processes. The environment and specifically packers' hands, as well as working surfaces contributed to microbiological contamination of various types after removal of the peel from individual sausages. The preliminary incubation procedure allowed detection of low numbers of spoilage microorganisms.

Air Microbiology↗
PubMed2005

Prediction of pathogen growth on iceberg lettuce under real temperature history during distribution from farm to table.

The growth of pathogenic bacteria Escherichia coli O157:H7, Salmonella spp., and Listeria monocytogenes on iceberg lettuce under constant and fluctuating temperatures was modelled in order to estimate the microbial safety of this vegetable during distribution from the farm to the table. Firstly, we examined pathogen growth on lettuce at constant temperatures, ranging from 5 to 25 degrees C, and then we obtained the growth kinetic parameters (lag time, maximum growth rate (micro(max)), and maximum population density (MPD)) using the Baranyi primary growth model. The parameters were similar to those predicted by the pathogen modelling program (PMP), with the exception of MPD. The MPD of each pathogen on lettuce was 2-4 log(10) CFU/g lower than that predicted by PMP. Furthermore, the MPD of pathogens decreased with decreasing temperature. The relationship between mu(max) and temperature was linear in accordance with Ratkowsky secondary model as was the relationship between the MPD and temperature. Predictions of pathogen growth under fluctuating temperature used the Baranyi primary microbial growth model along with the Ratkowsky secondary model and MPD equation. The fluctuating temperature profile used in this study was the real temperature history measured during distribution from the field at harvesting to the retail store. Overall predictions for each pathogen agreed well with observed viable counts in most cases. The bias and root mean square error (RMSE) of the prediction were small. The prediction in which mu(max) was based on PMP showed a trend of overestimation relative to prediction based on lettuce. However, the prediction concerning E. coli O157:H7 and Salmonella spp. on lettuce greatly overestimated growth in the case of a temperature history starting relatively high, such as 25 degrees C for 5 h. In contrast, the overall prediction of L. monocytogenes under the same circumstances agreed with the observed data.

Colony Count, Microbial↗
PubMed1992

Microbial contamination of ambient air by ultrasonic humidifier and preventive measures.

The microbially contaminated ultrasonic humidifier (UH) causes humidifier fever. The number of airborne viable bacteria was determined when the UH was operating, and other methods to humidify the air of hospital wards were also examined. A UH contaminated with 10(5) bacteria ml(-1), a level common in hospitals, increased the bacterial count in the air from 860 m(-3) to 88,000 m(-3) at a distance of 3 m from the humidifier. Thus UH in hospitals may contaminate the air and be a potential hazard to patients. Contamination was slight when a washable and disinfectable ultrasonic nebulizer was used with disinfection at 24 h intervals. In tracheostomy patients requiring a high degree of air humidification, ultrasonic nebulizers which are readily washed and disinfected are recommended.

Aerosols↗
PubMed2005

Isolation and characterization of a virulent Lactobacillus sanfranciscensis bacteriophage and its impact on microbial population in sourdough.

Thirty-five sourdough samples used for sweet and salted Italian baked products were checked for the presence of a virus active on Lactobacillus sanfranciscensis species. One phage, named EV3, was isolated and its phenotypic and genotypic features were investigated. It belonged to the Siphoviridae family (morphotype B1); its life cycle at 25 degrees C lasted 3 h with a burst size of about 30 viral particles per infected cell. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) showed one major structural protein of 35 kDa and four minor proteins. The genome, approximately 32 kb long, was a double-stranded linear DNA molecule with a pac-type system. Phage spreading into sourdough did not adversely affect acidification and volume increase of the dough neither lactobacilli counts; the propagation of viral particles was shown to be hindered. This is the first report of the isolation of a L. sanfranciscensis phage.

Bacteriolysis↗
PubMed1999

Salivary lactoferrin and low-Mr mucin MG2 in Actinobacillus actinomycetemcomitans-associated periodontitis.

Concentrations and output of lactoferrin and of low-Mr mucin MG2 were determined in saliva of subjects suffering from Actinobacillus actinomycetemcomitans-associated periodontal disease and healthy subjects. Periodontal patients were clinically examined and a microbiological sample was taken from the deepest bleeding pockets in each quadrant. The number of viable A. actinomycetemcomitans was determined in the sampled sites of each patient. The MG2 output in the diseased subjects (13.6 microg protein/min) was decreased at least by a factor three compared to periodontal healthy subjects (44.3 microg protein/min). On the other hand, output of lactoferrin was not significantly different in healthy (9.5 microg/min) and diseased subjects (7.6 microg/min). Western analyses demonstrated a higher iron-saturation of lactoferrin in diseased subjects in comparison with the healthy subjects. Lactoferrin degrading enzymes, probably derived from microbial sources, could be detected in saliva of the periodontally diseased subjects, but not in saliva of healthy subjects. The combination of iron-saturation and degradation of lactoferrin suggests that anti-microbial properties of lactoferrin are diminished in periodontitis patients. Moreover, the low concentration of mucin MG2 suggests a decline in mucin defence and consequently a higher susceptibility for oral infection. A negative correlation (r= -0.4, p < 0.05) between the number of subgingival A. actinomycetemcomitans and lactoferrin in saliva suggested that low concentrations of lactoferrin favour the growth of the bacterium. These data indicate that a decline in the salivary defence system might increase the risk for oral infection by A. actinomycetemcomitans.

Actinobacillus Infections↗
PubMed2003

Effectiveness of 2% chlorhexidine gel and calcium hydroxide against Enterococcus faecalis in bovine root dentine in vitro.

AIM: To evaluate the effectiveness of 2% chlorhexidine gluconate gel and calcium hydroxide (Ca(OH)2) as intracanal medicaments against Enterococcus faecalis. METHODOLOGY: One hundred and eighty dentine tubes prepared from intact freshly extracted bovine maxillary central incisors were infected in vitro for 7 days with E. faecalis. The specimens were divided into four groups, according to the intracanal medicament used, as follows: Group 1: 2% chlorhexidine gluconate gel; Group 2: calcium hydroxide in a viscous vehicle (polyethyleneglycol 400); Group 3: 2% chlorhexidine gluconate gel + calcium hydroxide and Group 4: Brain Heart Infusion (BHI) broth (control group). The medicaments were placed into the canal lumen and left there for experimental times of 1, 2, 7, 15 and 30 days. After each period, irrigation with sterile saline to remove the medicament was performed and the canals were dried with sterile paper points. Dentine chips were removed from the canals with sequential sterile round burs at low speed. The samples obtained with each bur were immediately collected in separate test tubes containing BHI broth. The tubes were incubated at 37 degrees C and daily observed for microbial growth, visualized by the medium turbidity. RESULTS: Chlorhexidine gel alone completely inhibited the growth of E. faecalis after 1, 2, 7 and 15 days. Calcium hydroxide allowed microbial growth at all experimental times. The combination of chlorhexidine and Ca(OH)2 was effective after 1 and 2 days demonstrating 100% antibacterial action; however, its antibacterial activity reduced between 7 and 15 days. CONCLUSION: Under the conditions of this study, it can be concluded that 2% chlorhexidine gel alone was more effective against E. faecalis than calcium hydroxide (P < 0.05). However, its antibacterial activity depended on how long it remained inside the root canal.

Animals↗
PubMed2005

Effect of climate on the bacteriology of chronic suppurative otitis media.

OBJECTIVES: We evaluated the correlation between the microbial content of chronic suppurative otitis media (CSOM) and regional climatic parameters. METHODS: We assessed the interrelations between monthly mean records of temperature, maximum temperature, atmospheric pressure, and humidity and the aerobic microbial flora in CSOM. RESULTS: Forty-three bacteria of Enterobacteriaceae, 67 staphylococcal spp, 51 Pseudomonas aeruginosa, 9 Streptococcus pneumoniae, 1 alpha-hemolytic Streptococcus, 1 Enterococcus sp, and 2 Edwardsiella tarda strains were recovered from 173 patients with CSOM. There was a good relationship between enteric bacteria and monthly mean temperature (r = 0.501) and significant colonization rates due to increasing monthly mean temperature (p = .040) and monthly mean maximum temperature values (p = .048). CONCLUSIONS: When the weather warmed, the frequency of isolation of enteric bacteria increased significantly. Temperature changes may affect the enteric bacterial colonization of CSOM.

Atmospheric Pressure↗
PubMed1996

The dynamics of microbial colonization of barrier membranes for guided tissue regeneration.

The microbial colonization of expanded polytetrafluoroethylene membrane by putative periodontopathogens at 3 minutes of intraoral manipulation was determined in 42 patients with 42 mandibular posterior two- to three-wall defects. Twenty patients exhibited no periodontal pockets of > or = 5 mm, other than the study site, and low levels of pathogens (group A). Twenty-two patients revealed multiple periodontal pockets of 5 mm or more and numerous pathogens (group B). Within the preceding 3 months of regenerative surgery, group A patients had received apically positioned flap surgery with osseous recontouring (except for the study site), and group B patients had been enrolled in a non-surgical maintenance program. The subgingival microbiota was examined prior to regenerative therapy, and the membrane microbiota was examined at 3 minutes and at the time of removal at 6 weeks by culture, DNA probes, and phase-contrast microscopy. The mean initial defect depth was 7.4 mm for group A and 7.2 mm for group B. At 6 months, the difference in mean clinical attachment gain was statistically significant (P < 0.001; group A: 3.4 mm; group B: 1.4 mm). At 3 minutes, putative pathogens were detected in seven (16.7%) membranes in group B (group Binfected), and the associated sites gained only 0.6 mm in clinical attachment at 6 months. Clinical attachment gain was modeled as a linear function of the explanatory variables (r2 = 86%). The presence of Porphyromonas gingivalis detected by DNA probe at 3 minutes was associated with 1.5 mm less expected gain (P = 0.0002). Total microbial counts and the percentage of Peptostreptococcus micros and Capnocytophaga species at baseline, and of motile rods on the membrane surface facing the gingiva at 6 weeks, were statistically significant negative predictors of clinical attachment. For each week the membrane remained covered, an additional 0.5 mm gain could be expected (P = 0.002); and for every 10 sites that exhibited bleeding on probing, the clinical attachment gain was 0.6 mm less at the site of regeneration (P < 0.0001). The present results showed that putative pathogens may colonize membranes within 3 minutes of intraoral manipulation. The patient group treated with periodontal osseous surgery revealed the lowest levels of periodontal pathogens in the membranes and exhibited the most gain in clinical attachment.

Adult↗
PubMed2005

Effect of disinfectants on microbial ecology in model distribution systems.

This research was conducted to assess the impact of various disinfectants on bacterial water quality within model distribution systems (i.e. annular reactors). After colonization with non-disinfected water, annular reactors were treated with relatively low doses of chlorine (0.4 mg/l), chlorine dioxide (0.15 mg/l), or chloramines (0.9 mg/l). Under the tested conditions, bacterial inactivation varied as a function of disinfectant type (ranking by efficiency per mg of oxidant: ClO2 > Cl2 > ClNH2) and sample type (bulk water vs. biofilm). Depending on the disinfectant, the log inactivation of suspended and attached bacteria were 0.7-1.2 and 0.5-1.0, respectively. The characterization of microbial communities in drinking water can be performed using biochemical and/or molecular methods. In this study, biochemical tests were used, showing that pseudomonad and pseudomonad-like bacteria, as in other studies, were the most predominant micro-organisms (e.g. Pseudomonas fluorescens, Brevundimonas vescularis). The ratio Gram-positive to Gram-negative organisms was 1 to 3. No drastic differences were observed between the non-treated and disinfected pipes. Based on the bacteriological data presented in these experiments, chlorine dioxide represents an alternative to chlorine for certain distribution systems.

Bacteria↗
PubMed2004

[Effects of free-air CO2 enrichment (FACE) on soil microbial biomass under rice-wheat rotation].

The effect of CO2 enrichment on soil microbial biomass in 0-5 cm and 5-10 cm soil layers under rice-wheat rotation was studied under the conditions of routine cultivation, irrigation and fertilization. The results showed that FACE treatment could significantly increase the amount of soil bacteria in 0-5 cm and 5-10 cm soil layers during rice jointing stage and wheat wintering and ripening stages. Elevated CO2 only significantly increased the amount of soil fungi in 0-5 cm soil layer during rice ripening stage. During the whole period of rotation, the amount of soil bacteria was greater than that of soil fungi.

Air↗
PubMedDate not supplied

Clinical evaluation of an ionic tooth brush on oral hygiene status, gingival status, and microbial parameter.

It has long been recognised that the presence of dental plaque leads to gingivitis and periodontal disease, as well as dental caries. Today tooth brushing is the most widely accepted method of removing plaque. Hence this present clinical study was undertaken to evaluate the effectiveness of an ionic toothbrush on oral hygiene status. For this study, 20 dental students in the age group of 18-20 years were included. All the subjects after undergoing dental prophylaxis were then provided with ionic toothbrushes, either active (equipped with lithium battery) or inactive (without lithium battery). Plaque index and gingival bleeding index were examined at 7th, 14th, and 21st day. Microbial assessment was done for detection of colony forming units (CFU) from the plaque samples which were collected on 0 day and 21st day, both before brushing and after brushing. Results shown a significant reduction in all the parameters and the reduction was more significant in active and inactive ionic toothbrush users. It was concluded that both active and inactive ionic toothbrushes reduced the plaque index and gingival bleeding index scores significantly and active ionic tooth brushes were more effective as compared to inactive ionic toothbrushes. There was no soft tissue trauma following the use of both type of toothbrushes, which showed that ionic toothbrushes were equally safe for regular long-term use.

Adolescent↗
PubMed1999

The influence of hay-packing techniques on the presence of saccharopolyspora rectivirgula.

Environmental factors influencing the growth, distribution and viability of thermophilic actinomycetes, especially Saccharopolyspora rectivirgula as an agent of extrinsic allergic alveolitis in farms workers, were studied. Total microbial count, eumycetes and thermophilic actinomycetes were determined on 96 hay samples, randomly collected, from small prismatic and large cylindrical bales, 30 air samples before and after animal feeding, and various surfaces in two farms located in the province of Reggio Emilia, Italy. The number of thermophilic actinomycetes (potentially responsible for hypersensitivity pneumonitis) was higher in hay samples from large cylindrical bales than in those from small prismatic bales. The structural characteristics of the buildings (barns with stalls, poor ventilation) and the feeding practices (manual handling of hay, constant presence of hay in feedings corridors) contributed to the dispersion of high levels of thermophilic actinomycetes spores (potentially responsible for extrinsic allergic alveolitis). The ventilation system proved to be inadequate in reducing the number of microorganisms present.

Agricultural Workers' Diseases↗