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PubMed2004

Antimicrobial activity of varying concentrations of sodium hypochlorite on the endodontic microorganisms Actinomyces israelii, A. naeslundii, Candida albicans and Enterococcus faecalis.

AIM: To determine the resistance of microorganisms associated with refractory endodontic infections to sodium hypochlorite used as a root canal irrigant. METHODOLOGY: Two strains each of Actinomyces naeslundii, Candida albicans and Enterococcus faecalis were tested as late logarithmic phase inocula, against sodium hypochlorite adjusted to 0.5, 1.0, 2.5 and 5.25% w/v. Contact times used were 0, 10, 20, 30, 60 and 120 s. In the case of E. faecalis, additional experiments used contact times of 1.0, 2.0, 5.0, 10.0 and 30.0 min. Anti-microbial action was halted by sodium thiosulphate addition. Survivors were measured primarily using viable counts on drop plates. Additionally, pour plates were used to count low colony-forming units (cfu) and dilutions to 10(-6) were used to count high cfu. RESULTS: All concentrations of NaOCl lowered cfu below the limit of detection after 10 s in the case of A. naeslundii and C. albicans. However, E. faecalis proved to be more resistant to NaOCl. Using 0.5% NaOCl for 30 min reduced cfu to zero for both strains tested. This compares with 10 min for 1.0%, 5 min for 2.5% and 2 min for 5.25% (P < 0.001). Regression analysis for the dependent variable log(e)(count + 1) with log(e)(time + 1) and concentration as explanatory variables gave rise to a significant interaction between time and concentration (P < 0.001). CONCLUSION: The published association of E. faecalis with refractory endodontic infection may result, at least partially, from high resistance of this species to NaOCl. This does not appear to be the case with A. naeslundii or C. albicans.

Actinomyces↗

PubMed2005

The complex oral microflora of high-risk individuals and groups and its role in the caries process.

The involvement of the oral biofilm in the caries process requires re-evaluation. The essential role of mutans streptococci (Streptococcus mutans and Streptococcus sobrinus) in the caries process is not proven. Acid production by dental plaque is not dependent upon the presence of mutans streptococci; caries occurs in the absence of these species and their presence does not necessarily indicate caries activity. Other oral bacteria, non-mutans streptococci, Actinomyces spp. and Bifidobacterium spp., are acidogenic and aciduric. They outnumber mutans streptococci in dental plaque, and there are data which support a role for these bacteria in the initiation and progression of caries. Molecular studies demonstrate the great diversity and complexity of the flora associated with caries. Many taxa identified have not been cultured and the role of these taxa is not known. We have, in mutans streptococci, good markers of disease but not necessarily the aetiological agents of the disease. Considerably more research is required to investigate the transition of tooth surfaces from being intact and sound to the white spot lesion stage. A combination of conventional and molecular approaches are required to elucidate the involvement of an individual taxon and of microbial populations with particular traits in the caries process.

Acids↗

PubMed2002

Quantitative tracing, by Taq nuclease assays, of a synechococcus ecotype in a highly diversified natural population.

Quantitative Taq nuclease assays (TNAs) (TaqMan PCR), nested PCR in combination with denaturing gradient gel electrophoresis (DGGE), and epifluorescence microscopy were used to analyze the autotrophic picoplankton (APP) of Lake Constance. Microscopic analysis revealed dominance of phycoerythrin (PE)-rich Synechococcus spp. in the pelagic zone of this lake. Cells passing a 3- micro m-pore-size filter were collected during the growth period of the years 1999 and 2000. The diversity of PE-rich Synechococcus spp. was examined using DGGE to analyze GC-clamped amplicons of a noncoding section of the 16S-23S intergenic spacer in the ribosomal operon. In both years, genotypes represented by three closely related PE-rich Synechococcus strains of our culture collection dominated the population, while other isolates were traced sporadically or were not detected in their original habitat by this method. For TNAs, primer-probe combinations for two taxonomic levels were used, one to quantify genomes of all known Synechococcus-type cyanobacteria in the APP of Lake Constance and one to enumerate genomes of a single ecotype represented by the PE-rich isolate Synechococcus sp. strain BO 8807. During the growth period, genome numbers of known Synechococcus spp. varied by 2 orders of magnitude (2.9 x 10(3) to 3.1 x 10(5) genomes per ml). The ecotype Synechococcus sp. strain BO 8807 was detected in every sample at concentrations between 1.6 x 10(1) and 1.3 x 10(4) genomes per ml, contributing 0.02 to 5.7% of the quantified cyanobacterial picoplankton. Although the quantitative approach taken in this study has disclosed several shortcomings in the sampling and detection methods, this study demonstrated for the first time the extensive internal dynamics that lie beneath the seemingly arbitrary variations of a population of microbial photoautotrophs in the pelagic habitat.

Calibration↗

PubMed2006

High-intensity pulsed electric field variables affecting Staphylococcus aureus inoculated in milk.

Staphylococcus aureus is an important milk-related pathogen that is inactivated by high-intensity pulsed electric fields (HIPEF). In this study, inactivation of Staph. aureus suspended in milk by HIPEF was studied using a response surface methodology, in which electric field intensity, pulse number, pulse width, pulse polarity, and the fat content of milk were the controlled variables. It was found that the fat content of milk did not significantly affect the microbial inactivation of Staph. aureus. A maximum value of 4.5 log reductions was obtained by applying 150 bipolar pulses of 8 mus each at 35 kV/cm. Bipolar pulses were more effective than those applied in the monopolar mode. An increase in electric field intensity, pulse number, or pulse width resulted in a drop in the survival fraction of Staph. aureus. Pulse widths close to 6.7 micros lead to greater microbial death with a minimum number of applied pulses. At a constant treatment time, a greater number of shorter pulses achieved better inactivation than those treatments performed at a lower number of longer pulses. The combined action of pulse number and electric field intensity followed a similar pattern, indicating that the same fraction of microbial death can be reached with different combinations of the variables. The behavior and relationship among the electrical variables suggest that the energy input of HIPEF processing might be optimized without decreasing the microbial death.

Animals↗

PubMed2000

Antioxidative/Antimicrobial effects of galangal and alpha-tocopherol in minced beef.

The antioxidant and microbial stabilities of galangal (Alpinia galanga) extract in raw minced beef were examined at 4 +/- 1 degree C. Raw minced beef containing galangal extracts (0 to 0.10%, wt/wt) were prepared. Lipid oxidation during refrigerated storage was assessed by monitoring malonaldehyde formation, using the thiobarbituric acid reactive substances method. In minced beef, added galangal extract improved oxidative stability. Galangal extract at higher concentrations of 0.05% and 0.10% (wt/wt) were also found to extend the shelf-life of minced beef. Addition of alpha-tocopherol (0.02%, wt/wt) to galangal extract (0.05%, wt/wt) were observed to increase the oxidative but not the microbial stability of minced beef during the storage of 7 days. Galangal extract may prove useful in inhibiting lipid oxidation and increasing microbial stability of minced meat.

Animals↗

PubMed2004

[Effects of forest restoration patterns on soil microbial communities].

In this paper, soil microbial community properties of five vegetation patterns were measured by bacterial, microbial biomass carbon and metabolic diversity (BIOLOG) assays to evaluate the effects of different forest restoration patterns on soil microbial community. The results showed that among five sampling sites, soil microbial biomass carbon and bacterial amount were the highest under natural secondary forest, while those in CK were the least. In BIOLOG assays, the average well colour development (AWCD) and the richness and diversity indices indicated the differences of microbial metabolic diversity. The variation tendency of the indices was the same as that of microbial biomass and bacterial amount. It is suggested that under natural secondary forest, soil microbial community had a stronger ability of utilizing carbon source and a greater functional diversity than that in plantations and CK. The metabolic diversity of microbial communities in 0-20 and 20-40 cm soil layers showed a fairly good correlation with root biomass (r = 0.933, P < 0.05; r = 0.925, P < 0.05). In a word, soil microbial biomass, bacterial amount and metabolic diversity patterns were the highest under natural secondary forest, and natural restoration should be more propitious to improve the structure and function of soil microbial community.

Biodiversity↗

PubMed1990

[Colonization by pyocyanic bacillus and its treatment in cystic fibrosis].

In cystic fibrosis infection is localized to the bronchi and self-perpetuated by a disorder of mucociliary clearance. At a certain stage of the disease infection is caused by Pseudomonas aeruginosa (PA), and the patient cannot get rid of it as cystic fibrosis reduces his defence mechanisms against this organism, a naturally weak pathogen. The presence and significance of persistent bronchial PA infection result from complex phenomena which have been summarized as "an opportunistic organism in a host whose defences have been very peculiarly compromised". The toxicity of PA and the inappropriate inflammatory response of the host concur to create permanent alveolar lesions which are gradually spreading out. The effectiveness of antibiotics depends on the organism and its resistance, on pharmacokinetic factors bringing the drug in situ and on local conditions of redox, physico-chemical environment and nutrition. Other factors intervene more roughly, including patient's age, liver impairment, lung anatomy (excluded areas), general malnutrition and vitamin deficiencies. Thus, the part played by other treatments in the antibiotic therapy of cystic fibrosis can no longer be ignored, just as it is no longer sensible to limit the use of antibiotics to obvious infections. To evaluate the effectiveness of antibiotics is not easy, but it can be demonstrated beyond any doubt when the above mentioned factors are taken into account. The use of antibiotics creates practical problems relating to their cost, their dosage, their side-effects, the adequacy of therapeutic infrastructures and, above all, it raises the question of short- and long-term changes in microbial ecology.

Adolescent↗

PubMed2005

The effect of Virkon S fogging on survival of Salmonella enterica and Staphylococcus aureus on surfaces in a veterinary teaching hospital.

The objective of the study was to determine the disinfection efficacy of aerosolizing (cold fogging) Virkon S on survival of Stahpylococcus aureus and Salmonella enterica on different surfaces. Two experiments were conducted in different locations. Salmonella enterica and S. aureus were grown in broth culture and then seeded into pre-marked areas in each location and allowed to dry. Virkon S (1%) was aerosolized into the rooms (approximately 1L of per 30 m(3)). Samples were collected pre- and post-fogging for quantitative cultures to evaluate the efficacy of aerial disinfection. The reduction of S. enterica or S. aureus counts ranged from 3.40 to 0.95 log(10) (Salmonella) or 4.92 to 0.02 log(10) (Staphylococcus). The greatest reduction was evident in samples collected from non-porous horizontal surfaces, which were not obstructed from the air flow. These results indicate that fogging with Virkon S could be beneficial in routine disinfection of pre-cleaned surfaces. The benefits of routine use of cold fogging with Virkon S in veterinary hospital settings would include its wide-range antimicrobial action and minimal working-men power required to disinfect large areas. Also, fogging would potentially minimize microbial contamination in the hard to reach areas.

Aerosols↗

PubMed1991

Performance and ruminal function development of young calves fed diets with Aspergillus oryzae fermentation extract.

Neonatal Holstein heifer (n = 72) and bull (n = 40) calves were used to study the effects of Aspergillus oryzae fermentation extract (Amaferm) on their performance and on rumen development. The starter diets were formulated to achieve Amaferm consumption of 0, .5, 1, or 3 g per calf daily. Calves were fed milk daily and allowed to consume starter and a mixture of alfalfa and bromegrass hay ad libitum. Weaning was when calves consumed 550 g of starter on 2 consecutive d. Weight gain and feed consumption were recorded weekly. Forty of the heifer calves, 10 from each treatment, were selected randomly to study the effects of Amaferm on ruminal fermentative development. Ruminal fluid samples were collected for pH, ruminal fermentation products, and for bacterial enumerations. Overall, Amaferm-supplemented calves were weaned 1 wk earlier than unsupplemented calves. They had higher total VFA, propionate, and acetate concentrations in the rumen than unsupplemented calves. Total anaerobic, hemicellulolytic, and pectinolytic bacterial counts were higher; cellulolytic bacterial counts tended to be higher for the Amaferm-supplemented calves than for controls. In general, Amaferm-supplemented calves had greater ruminal microbial activity than those not fed Amaferm.

Animal Feed↗

PubMed1999

Real-time monitoring of Escherichia coli O157:H7 adherence to beef carcass surface tissues with a bioluminescent reporter.

A method for studying bacteria that are attached to carcass surfaces would eliminate the need for exogenous sampling and would facilitate understanding the interaction of potential human food-borne pathogens with food animal tissue surfaces. We describe such a method in which we used a bioluminescent reporter strain of Escherichia coli O157:H7 that was constructed by transformation with plasmid pCGLS1, an expression vector that contains a complete bacterial luciferase (lux) operon. Beef carcass surface tissues were inoculated with the bioluminescent strain, and adherent bacteria were visualized in real time by using a sensitive photon-counting camera to obtain in situ images. The reporter strain was found to luminesce from the tissue surfaces whether it was inoculated as a suspension in buffer or as a suspension in a bovine fecal slurry. With this method, areas of tissues inoculated with the reporter strain could be studied without obtaining, excising, homogenizing, and culturing multiple samples from the tissue surface. Use of the complete lux operon as the bioluminescent reporter eliminated the need to add exogenous substrate. This allowed detection and quantitation of bacterial inocula and rapid evaluation of adherence of a potential human pathogen to tissue surfaces. Following simple water rinses of inoculated carcass tissues, the attachment duration varied with different carcass surface types. On average, the percent retention of bioluminescent signal from the reporter strain was higher on lean fascia-covered tissue (54%) than on adipose fascia-covered tissue (18%) following water washing of the tissues. Bioluminescence and culture-derived viable bacterial counts were highly correlated (r2 = 0.98). Real-time assessment of microbial attachment to this complex menstruum should facilitate evaluation of carcass decontamination procedures and mechanistic studies of microbial contamination of beef carcass tissues.

Abattoirs↗

PubMed1998

Aspects of microbiological and chemical quality of turmus, lupin seeds debittered by soaking in water.

Eleven species of spherical lactic acid bacteria (LAB) belonging to the genera Leuconostoc, Lactococcus, Enterococcus and Pediococcus were the predominant microorganisms in 40 samples of turmus, ready-to-eat lupin seeds debittered by boiling and soaking in water. The average counts of the LAB in the 20 winter samples and the 20 summer samples were 7.4 and 8.7 log CFU/g, respectively. The averages of the Enterobacteriaceae counts were 5.1 and 6.6 log CFU/g, respectively, and the 11 species isolated belonged to the genera Enterobacter, Citrobacter, Escherichia and Klebsiella. The average yeast counts in winter and summer samples were 3 and 3.2 log CFU/g, respectively, and the 5 species isolated were in the genera Saccharomyces, Cryptococcus, Rhodotorula and Candida. Although Salmonella was not isolated from any sample and the Staphylococcus aureus count in all samples was < 1 log CFU/g, microbial hazards could be associated with the high Enterobacteriaceae counts and the presence of Escherichia coli. Total alkaloid concentration in 30% of the samples examined was higher than 0.02%, thus making the seeds a potential chemical hazard. Boiling the turmus directly before consumption and discarding the seeds with a bitter taste may help in avoiding some of the microbial and chemical hazards which could be associated with turmus consumption.

Alkaloids↗

PubMed2006

Correlation of clinical outcome of integra application with microbiologic and pathological biopsies.

BACKGROUND: Integra, a dermal replacement template consisting of bovine collagen, chondroitin-6-sulfate, and a silastic sheet is a postexcisional treatment for deep partial to full thickness burns where autograft is limited. This study correlates Integra histology and quantitative microbiology cultures with clinical outcomes after autografting. METHODS: Charts of 29 burn patients who underwent Integra treatment and neodermis biopsy at the time of ultra thin autografting were reviewed. We analyzed microbial contamination, inflammatory reaction, and autograft take. RESULTS: The mean burn size and age were 43% total body surface area and 39 years old, respectively. In quantitative neodermis cultures, 90% of samples had bacterial growth; nine samples (31%) had > 10(5) colony forming units per gram. The most common organism was Staphylococcus aureus (31%). Patients with quantitative bacterial counts >10(5) CFU/g received targeted systemic antibiotics. Integra take (83%) and autograft take (92%) were acceptable even in patients with high bacterial counts (78% Integra take; 86% autograft take). More than 50% of biopsies had dermal regeneration similar to normal dermis; foreign body reactions were unusual. Histologic evidence of inflammation, especially polymorphonuclear cells, was increased in biopsies with high bacterial counts. CONCLUSION: Integra and autograft take can be acceptable even with high bacterial counts if wounds are treated with appropriate targeted topical and systemic antibiotics in the presence of microbial contamination. Neodermis biopsies showed fibrous in-growth congruent with existing Integra fibers with minimal foreign body reaction. These data support Integra use as a safe and effective treatment modality in patients with major burns.

Administration, Topical↗

PubMed2004

Relative ileal amino acid flows and microbial counts in intestinal effluents of Goettingen Minipigs and Saddleback pigs are not different.

We explored the suitability of Goettingen Minipigs as models to measure ileal AA digestibility and evaluate dietary proteins for conventional pigs. Further, a potential for secondary ileal microbial colonization 5 mo after establishing end-to-end ileorectal anastomosis was investigated. Goettingen Minipigs (BW 18 kg) and Saddleback pigs (BW 27 kg) fitted with end-to-end ileorectal anastomosis were fed six diets based on barley and oilseed meals and three diets based on wheat and milk powder differing in total and ileal digestible lysine. Apparent ileal digestibilities of CP (N x 6.25) and of 20 AA were determined. No differences (P = 0.062 to 0.982) were found in AA apparent ileal digestibilities between breeds. Therefore, Minipigs are a reasonable model to estimate apparent ileal digestibility of AA for evaluation of dietary proteins. However, the apparent ileal digestibility of CP (P = 0.048) was higher in Minipigs than in Saddleback pigs (barley and oilseed meals-based diets 70% vs. 66%; wheat and milk powder-based diets 80% vs. 77%), which is probably due to a smaller contribution of non-AA-nitrogen in the ileal effluent of Goettingen Minipigs. For lysine, the apparent ileal digestibilities (means of both breeds) ranged from 78 to 85% in wheat and milk powder-based, and 70 to 78% in barley and oilseed-based diets. Experimentally derived concentrations of ileally digestible lysine confirmed the values predicted from a published table. Microbial counts were not affected by breed as shown for lactobacilli, with 9.1+/-0.2 and 9.1+/-0.2 (P = 0.977), enterococci with 4.8+/-0.3 and 5.6+/-0.4 (P = 0.162), and yeasts with 4.6+/-0.3 and 4.6+/-0.4 (P = 0.906) log cfu/g effluent for Goettingen Minipigs and Saddleback pigs, respectively. The counts did not change over 5 mo, suggesting that no secondary microbial colonization occurred in pigs with end-to-end ileorectal anastomosis.

Amino Acids↗

PubMed1996

Flow cytometry and cell sorting of heterogeneous microbial populations: the importance of single-cell analyses.

The most fundamental questions such as whether a cell is alive, in the sense of being able to divide or to form a colony, may sometimes be very hard to answer, since even axenic microbial cultures are extremely heterogeneous. Analyses that seek to correlate such things as viability, which is a property of an individual cell, with macroscopic measurements of culture variables such as ATP content, respiratory activity, and so on, must inevitably fail. It is therefore necessary to make physiological measurements on individual cells. Flow cytometry is such a technique, which allows one to analyze cells rapidly and individually and permits the quantitative analysis of microbial heterogeneity. It therefore offers many advantages over conventional measurements for both routine and more exploratory analyses of microbial properties. While the technique has been widely applied to the study of mammalian cells, is use in microbiology has until recently been much more limited, largely because of the smaller size of microbes and the consequently smaller optical signals obtainable from them. Since these technical barriers no longer hold, flow cytometry with appropriate stains has been used for the rapid discrimination and identification of microbial cells, for the rapid assessment of viability and of the heterogeneous distributions of a wealth of other more detailed physiological properties, for the analysis of antimicrobial drug-cell interactions, and for the isolation of high-yielding strains of biotechnological interest. Flow cytometric analyses provide an abundance of multivariate data, and special methods have been devised to exploit these. Ongoing advances mean that modern flow cytometers may now be used by nonspecialists to effect a renaissance in our understanding of microbial heterogeneity.

Bacteria↗

PubMed2000

Determination of metabolic activity of streptomycetes in soil microcosms.

Two Streptomyces griseus strains were isolated from different soil types. S. griseus CAG17 strain was isolated from an agricultural area with low organic matter but rich in phosphorus content and S. griseus 26K strain was isolated from a forest area rich in organic matter with a low phosphorus content. The survival and metabolic activity of these isolates were studied in dynamic sterile soil microcosm systems. The fitness of each isolate was studied by re-inoculation in a soil type different from its origin. Maximum percentage of germination and respiration rates occurred within the first 48 h after each soil turnover (removal and addition of certain soil volumes). Data suggested that S. griseus CAG17 survived better independently of the soil type in comparison with S. griseus 26K which sporulated within the first 12 h after inoculation. Incubation temperatures did affect the lifecycles in relation to soil type. For example, the lowest temperature tested, 22 degrees C, was more favourable for extended germination and adaptation in general but revealed lesser spore numbers in the 'foreign' soil environment. Monitoring metabolic activity by estimation of urease, phosphatases and dehydrogenase-specific activities, between 18 and 35 degrees C incubation temperatures, was a reliable method for studying the survival and growth of streptomycete populations in soil. Results also confirmed that respiration rate and enzyme-specific activity corresponded with spore counts in long-term experiments which were designed for the investigation of survival and growth of S. griseus CAG17. Under selective pressure by heavy metals, in soil microcosm systems, metabolic activity proved a useful tool for the investigation of streptomycete activity. These methods could also be applied in agricultural field studies for monitoring microbial populations under conditions where various 'pollutants' are present in soil samples.

Colony Count, Microbial↗

PubMed2006

Degradation of tributyltin in microcosm using Mekong River sediment.

The degradation of tributyltin (TBT) and changes of bacterial number and community structures were investigated in microcosms using the sediment collected from the Mekong River, Vietnam. Concentrations of TBT in sediments were less than 0.62 ng/g (dry wt), lower than those reported from other areas. TBT-resistant bacteria were found in the three sampling sites, and the occurrence rates were 11-16% out of the total viable count. In this microcosm experiment, initial concentration of TBT [1.0-1.4 microg/g (dry wt)] decreased to 0.6 microg/g (dry wt) during 150 days, whereas that in the control microcosm with autoclaved sediment did not change, indicating that Mekong River sediment contains high TBT-degrading activity by microorganisms. The occurrence of TBT-resistant bacteria and the bacterial community structures monitored by denaturing gradient gel electrophoresis were almost the same between test and control groups, indicating that the addition of TBT had little influence on microbial community structure. Mekong River sediment seems to have a stable microbial community against TBT pollution.

Bacteria↗

PubMed1998

Microbiological profile and potential hazards associated with imported and local brands of tomato paste in Nigeria.

Cans of three tomato paste brands (two of which are imported and one produced locally) showing defective or normal appearance were purchased from various retail outlets and analysed for microbial composition and pH values. Substantially higher total viable counts were observed in samples from defective cans but the lowest population was found in the local brand. Ratio of mesophilic to thermophilic micro-organisms increased in samples obtained from cans showing visible defects. Anaerobic spore counts were higher than the aerobic population in both normal and defective cans, but the counts varied with the brands. Four dominant bacterial genera (Bacillus, Clostridium, Lactobacillus and Leuconostoc) were isolated from the samples with the greater proportion being spore-formers. Percentage occurrence of Clostridium thermosaccharolyticum was appreciably higher in samples from defective cans while a preponderance of Lactobacillus occurred in samples from normal cans. Of the moulds isolated, Absidia and Aspergillus fumigatus showed a higher percentage in defective cans. pH values higher than the critical safe level of 4.6 were found in cans with visible defects and greater microbial diversity with higher microbial load was more often associated with these samples. Imported brands showed more undesirable microbial quality and pH values, making them potentially hazardous.

Bacteria, Aerobic↗

PubMed1994

The effectiveness of three different strengths of chlorhexidine mouthrinse.

Dental caries in dentate elderly patients may be controlled with chlorhexidine. The purpose of this study is to establish the effectiveness of two low-concentration chlorhexidine mouthrinses in reducing the microbial counts of cariogenic bacteria in a sample of institutionalized elders. Stimulated saliva samples from all subjects before treatment produced counts greater than or equal to 105 colony-forming units (CFU)/mL of lactobacilli and/or mutans streptococci. Treatment consisted of daily rinsing with 4.0 mL of mouthrinse before bed for 14 days. Bacterial counts were re-assessed two weeks after commencing treatment. The mean reduction in mutans streptococci counts in subjects receiving the regular-strength chlorhexidine mouthrinse (Group B) was significantly greater than for subjects using either of the low-concentration rinses (Groups A and C). These findings failed to demonstrate the effectiveness of the lower-concentration mouthrinses (Groups A & C).

Aged↗