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PubMed1997

Microbial colonization of a closed growth chamber during hydroponic cultivation of lettuce.

The goal of this study was to characterize sessile and planktonic microbiota that developed during two successive hydroponic cultures of lettuce in a closed chamber system. Coupons of polyvinyl chloride (PVC) placed in the nutrient solution lines were removed periodically, as were samples of the nutrient solutions and condensate from the air-handling system. The bacteria and fungi present on the coupons and in fluid samples were enumerated by direct plate counts. Disinfecting the hydroponic system with 0.1% hypochlorite and 0.1 N nitric acid reduced the bacterial densities in biofilm samples from 1 x 10(7) CFU/10 cm2 to 1 x 10(1) CFU/10 cm2 and eliminated culturable fungi; Staphylococcus sp., Pseudomonas sp., and Micrococcus sp. survived this procedure. Bacterial and fungal concentrations in all samples returned to predisinfection levels after 2 days of plant growth. Pseudomonas and Acremonium predominated both before and after disinfection. Fungal concentrations never exceeded 7 x 10(2) CFU/10 cm2. The coupon microbiota differed from that of the rhizoplane at harvest. Overall, the greatest numbers of species were found on the rhizoplane samples collected during the second crop. The microbial community changed little during individual crops or between successive crops. Diversity indices remained relatively constant for all samples.

Bacteria↗

PubMed1992

Electron-microscopic description of accretions occurring on tips of infected and non-infected central venous catheters.

OBJECTIVE: The purpose of the study was do describe the architecture of accretions occurring on the tips of central venous catheters (CVC). DESIGN: A conservative procedure was used followed by two different techniques of electron microscopy. SETTING AND PATIENTS: the study included 19 catheters which have been used on intensive cared adults, and which were chosen among those of parallel 300 CVC study. MEASUREMENTS AND RESULTS: CVC were considered sterile, contaminated, colonized or infected according to microbiological and clinical criteria. CVC were found to remain much cleaner than in past descriptions. When present, accretions were located on the olive-shaped end, and displayed stratified structures with three types of material: amorphous material, thrombus components and inflammatory cells. Bacteria were not seen, even on culture positive CVC. Candida albicans was found on one CVC in the cytoplasm of granulocytes, and made no direct contact with the plastic surface. CONCLUSION: This technique should contribute to the understanding of the pathobiology of CVC infection and provide information proving or precluding the involvement of microbial adherence to polymers in vivo.

Anti-Bacterial Agents↗

PubMed2005

Synthesis and biological evaluation of novel angularly fused polycyclic coumarins.

In a three-step sequence, an array of angularly fused polycyclic heterocycles with coumarin, benzofuran and pyridine rings were synthesized from 4-bromomethylcoumarins and salicylonitrile. All the final compounds were fully characterized and screened for anti-microbial, anti-inflammatory and analgesic activities. Several compounds exhibited promising inflammation inhibiting and anti-microbial properties.

Analgesics↗

PubMed2001

An in-use evaluation of an alcohol-based pre-surgical hand disinfectant.

OBJECTIVE: To determine whether alcohol hand disinfection is an effective alternative to traditional agents for the pre-surgical scrub. DESIGN: A prospective clinical trial of a 70% isopropanol pre-surgical hand disinfectant. SETTING: The operating room suites at two hospital sites in British Columbia. METHODS: Cases were selected to evaluate both short and longer procedures. The hand disinfectant was compared to agents in current use as surgical scrubs (4% chlorhexidine and 7.5% povidone-iodine). Surgical technique and glove use were not modified. Pre- and postoperative fingertip impression and "glove-juice" cultures were used to determine microbial burden, and hands were evaluated for skin integrity. RESULTS: There was no statistical difference between the microbial hand counts following use of the alcohol-based product or the current agents, for cases less than 2 hours' duration. Comparison of longer surgical cases revealed significantly better pre- and postoperative culture results with the alcohol hand rinse, but analysis of matched pairs showed no significant difference in microbial counts. The alcohol hand rinse was equivalent to the operative scrub in terms of skin integrity and user acceptability. CONCLUSION: An alcohol hand rinse was equivalently effective in reducing microbial hand counts as the traditional pre-surgical scrub, both immediately after hand disinfection and at the end of the surgical procedure.

2-Propanol↗

PubMed1993

The association of carious dentin microflora with tissue changes in human pulpitis.

Correlations were sought between the number and type of microorganisms recovered from sampled carious dentin and the cellular responses observed in dental pulpal tissues from a sample of 65 vital, carious teeth extracted from adult humans who had declined the option of tooth restoration. Standardized homogenates of carious dentin were plated using selective and nonselective media under anaerobic and microaerophilic conditions. Pulpal responses were characterized histopathologically on the basis of the nature of the cellular infiltrate and the extent of degenerative changes. A significant association between the number of Prevotella intermedia and Prevotella melaninogenica in carious dentin and extensive, principally mononuclear, inflammatory infiltration was evident despite a high degree of complexity and intersubject variability in the microbial flora. There was no apparent association between other microorganisms or total microbial load and the histopathological category.

Actinomyces↗

PubMed2006

Physiological traits of bacterial strains isolated from phenol-degrading aerobic granules.

The physiological characteristics of ten bacterial strains isolated from phenol-degrading aerobic granules were evaluated in order to identify competitive traits for dominant growth in aerobic granules. The ten strains showed a wide diversity in specific growth rates and oxygen utilization kinetics, and could be divided into four catabolic types of phenol degradation. While some strains degraded phenol mainly via the meta pathway or the ortho pathway, other strains degraded phenol via both these pathways. The ten strains also exhibited high levels of autoaggregation and coaggregation activity. Within the collection of ten strains, 36.7% of all possible strain pairings displayed a measurable degree of coaggregation. Strain PG-08 possessed the strongest autoaggregation activity and showed significant coaggregation (coaggregation indices of 67% to 74%) with PG-02. The three strains PG-01, PG-02 and PG-08 belonging to dominant groups in the granules possessed different competitive characteristics. Microcosm experiments showed the three strains could not coexist at the high phenol concentration of 250 mg L(-1), but could coexist at lower phenol concentrations in a spatially heterogeneous environment. This study illustrated that the spatial heterogeneity provided by the aerobic granules led to niche differentiation and increased physiological diversity in the resident microbial community.

Aerobiosis↗

PubMed2004

Modification of spatial distribution of 2,4-dichlorophenoxyacetic acid degrader microhabitats during growth in soil columns.

Bacterial processes in soil, including biodegradation, require contact between bacteria and substrates. Knowledge of the three-dimensional spatial distribution of bacteria at the microscale is necessary to understand and predict such processes. Using a soil microsampling strategy combined with a mathematical spatial analysis, we studied the spatial distribution of 2,4-dichlorophenoxyacetic acid (2,4-D) degrader microhabitats as a function of 2,4-D degrader abundance. Soil columns that allowed natural flow were percolated with 2,4-D to increase the 2,4-D degrader abundance. Hundreds of soil microsamples (minimum diameter, 125 microm) were collected and transferred to culture medium to check for the presence of 2,4-D degraders. Spatial distributions of bacterial microhabitats were characterized by determining the average size of colonized soil patches and the average number of patches per gram of soil. The spatial distribution of 2,4-D degrader microhabitats was not affected by water flow, but there was an overall increase in colonized patch sizes after 2,4-D amendment; colonized microsamples were dispersed in the soil at low 2,4-D degrader densities and clustered in patches that were more than 0.5 mm in diameter at higher densities. During growth, spreading of 2,4-D degraders within the soil and an increase in 2,4-D degradation were observed. We hypothesized that spreading of the bacteria increased the probability of encounters with 2,4-D and resulted in better interception of the degradable substrate. This work showed that characterization of bacterial microscale spatial distribution is relevant to microbial ecology studies. It improved quantitative bacterial microhabitat description and suggested that sporadic movement of cells occurs. Furthermore, it offered perspectives for linking microbial function to the soil physicochemical environment.

2,4-Dichlorophenoxyacetic Acid↗

PubMed2005

Chemical and microbiological stability of waste sludge from paper industry intended for brick production.

Due to its chemical composition, waste sludge generated in the paper industry may be used as a raw material for brick production. Brick manufacture is limited to the warmer months of the year whereas sludge is produced continuously by different effluent treatment devices. Therefore, it has to be stored until further processing. For this reason, it is essential that it is not subject to significant chemical and microbiological decomposition during storage. In the experiment, sludge from a tissue paper mill was tested for its stability. It was stored for several weeks during winter and summer periods in a pile, 2 m in height, in an open but covered store. Different leachable organic and inorganic compounds indicating possible ongoing deterioration processes, as well as pH value, redox potential, temperature, humidity and dry matter content were evaluated weekly in water extracts of homogenized sludge samples. According to the test results, the material may be considered to be chemically and microbiologically stable as there was practically no emission of odorous and toxic compounds such as H2S, NH3 and butyric acid despite prolonged storage times and elevated environmental temperatures. All the microbial species identified in the sludge during storage belong to the typical microflora of the environment.

Bacteria, Aerobic↗

PubMed1992

Day-long reduction of oral malodor by a two-phase oil:water mouthrinse as compared to chlorhexidine and placebo rinses.

Few scientific investigations have addressed the ability of mouthrinses to reduce oral malodor for periods longer than 3 hours. In the present report, we have employed simple, recently described techniques to assess the day-long reduction in oral malodor of a novel 2-phase oil:water mouthrinse (TPM), as compared to a corresponding placebo rinse, and to a commercial 0.2% chlorhexidine mouthrinse. Sixty dental students were divided randomly into 3 groups, and instructed to use one of the rinses prior to bedtime and the following morning. Measurements carried out in the late afternoon, about 8 to 10 hours following rinsing, were compared with baseline measurements carried out in the late afternoon of the previous day. Volatile sulphide levels were measured using a portable industrial sulphide monitor. Microbial levels were estimated using a simple rinsing technique employing sterilized milk. These quantitative techniques were corroborated by organoleptic (hedonic) ratings of a single odor judge. Both TPM and chlorhexidine brought about significant decreases in volatile sulphides (P less than 0.05) as compared to the placebo group. These results were corroborated by the organoleptic data. Similarly, both chlorhexidine and TPM were highly effective in reducing microbial levels as measured by the rinsing technique, in comparison to the placebo group. Chlorhexidine appeared to be more effective than TPM in all measurement categories, although only in the case of microbial activity was there a significant (P less than 0.05) difference between the two groups.

Bacteria↗

PubMed2000

Viability of bifidobacteria in commercial dairy products during refrigerated storage.

Commercial milk and two brands of yogurt containing bifidobacteria were obtained from retail outlets. All products were evaluated for viability of bifidobacteria and lactic acid bacteria during refrigerated storage at 4 degrees C. Milk was evaluated at 9, 6, and 3 days prior and past its expiration date. The yogurts were evaluated at 3, 2, and 1 week prior and past their expiration. Viability of bifidobacteria and lactic acid bacteria in milk and yogurt remained above 10(6) CFU/ml or g until the expiration date of the respective products. This microbial concentration is the recommended minimum dose to receive the health benefits of these organisms.

Animals↗

PubMed2004

Stationary-phase acid resistance and injury of recent bovine Escherichia coli O157 and non-O157 biotype I Escherichia coli isolatest.

Stationary-phase acid resistance and the induction of acid resistance were assessed for recent bovine carcass isolates of Escherichia coli, including 39 serotype O157 strains and 20 non-O157 strains. When grown to stationary phase in the absence of glucose and without prior acid exposure, there was a range of responses to a pH challenge of 6 h at pH 2.5. However, populations of 53 of the 59 E. coli isolates examined were reduced by less than 2.00 log CFU/ml, and populations of 24 of these isolates were reduced by less than 1.00 log CFU/ml. In contrast, there was little variation in population reductions when the E. coli were grown with glucose and preadapted to acidic conditions. With few exceptions, acid adaptation improved survival to the acid challenge, with 57 of the 59 isolates exhibiting a log reduction of less than 0.50. Differences in acid resistance or the ability to adapt to acidic conditions between E. coli O157:H7 and non-O157 commensal E. coli were not observed. However, we did find that the E. coli O157 were disposed to greater acid injury after the low pH challenge than the non-O157 E. coli, both for cells that were and were not adapted to acidic conditions before the challenge. The enhancement of low pH survival after acid adaptation that was seen among these recent natural isolates of E. coli O157 further supports the idea that the previous environment of this pathogen should be a consideration when designing microbial safety strategies for foods preserved by low pH and acid.

Acetic Acid↗

PubMed2000

The microbial flora of the gastrointestinal tract and the cleaning of flexible endoscopes.

Technologic advances in the last 30 years have resulted in the development of complex, expensive, and heat sensitive medical instrumentation, including flexible gastrointestinal endoscopes. Because of the design complexity and the region of use, gastrointestinal endoscopes present special challenges to cleaning. If instruments are not properly cleaned the disinfection or sterilization procedure can fail and increase the possibility of infection transmission from one patient to another. Although the cleaning process removes intestinal microflora, the washing process itself may introduce a saprophytic or environmental microbial flora. It has been repeatedly shown that endoscope cleaning, not the disinfection or sterilization procedure, controls the success of the reprocessing procedure.

Colony Count, Microbial↗

PubMed2006

Effects of mixing low amounts of orange peel (Citrus reticulata) with hydrocarbon-contaminated soil in solid culture to promote remediation.

The effect of mixing low amounts of orange peel (Citrus reticulata) with a soil contaminated with hydrocarbons (58,000 mg kg(-1) soil) for promoting the soil remediation in solid culture was studied. The experimental design was established in solid culture at soil/orange (Citrus reticulata) peel ratios of 100:0, 98:2, 96:4, 94:6 and 92:8, at 30% humidity and a C:N:P ratio of 100:10:1, for 15, 60 and 90 days, respectively. The total petroleum hydrocarbons (TPHs) decreased significantly (69%) after 15 days in the treatment with a soil to orange peel ratio of 92:8. Furthermore, in this treatment bacterial counts increased from 17 to 20 ln CFU (2.6 x 10(6) to 5 x 10(8)), while the fungal count was 11 ln CFU (6.5 x 10(4)) at initial and final time of treatment. An increase in microbial respiration activity and TPH removal (69%) was observed at other soil/orange peel ratios after 60 days when moisture content and nutrients were adjusted; however, N and P were not consumed at a great extent.

Biodegradation, Environmental↗

PubMed2004

Efficacy of A-dec's ICX dental unit waterline treatment solution in the prevention and treatment of microbial contamination in dental units.

OBJECTIVE: Even though some chemical agents can disinfect biofilms in dental unit waterlines, there remains concern that all remnants of the biofilm matrix are not eliminated. Even with periodic treatments, the bacterial populations in dental unit waterlines recur rapidly. In addition, with some previously tested products, patient safety, as well as toxic, caustic and corrosive residual chemicals are also a concern. This study evaluated ICX, A-dec's new water treatment solution, in a series of experiments for prevention, microbial spectrum of activity, minimum inhibitory time determination, and treatment of established biofilms. METHODOLOGY: New dental unit waterline tubing was treated continuously during simulated patient care over 28 days with municipal water. It was then treated with ICX. Effluents from lines with established biofilms (averaging > 10(4) CFU/ml at day 0) were treated to assess levels of CFU counts within 21 days of exposure to ICX. RESULTS: Tubing treated with ICX did not develop a detectable biofilm using ruthenium red staining, and microbes in effluents remained undetectable. CONCLUSION: ICX is effective in maintaining the effluent within the American Dental Association's and the Centers for Disease Control's recommendation for < 500 CFU/ml. In addition, considering the preliminary finding that ICX reduces microbial contamination of effluents from established biofilm lines, it may be useful in long-term treatment alone or when coupled with a shock treatment to assist in biofilm destruction.

Biofilms↗

PubMed2003

In situ exposure to low herbicide concentrations affects microbial population composition and catabolic gene frequency in an aerobic shallow aquifer.

The aim of this study was to evaluate how the in situ exposure of a Danish subsurface aquifer to phenoxy acid herbicides at low concentrations (<40 micro g l(-1)) changes the microbial community composition. Sediment and groundwater samples were collected inside and outside the herbicide-exposed area and were analyzed for the presence of general microbial populations, Pseudomonas bacteria, and specific phenoxy acid degraders. Both culture-dependent and culture-independent methods were applied. The abundance of microbial phenoxy acid degraders (10(0) to 10(4) g(-1) sediment) was determined by most probable number assays, and their presence was only detected in herbicide-exposed sediments. Similarly, PCR analysis showed that the 2,4-dichlorophenoxyacetic acid degradation pathway genes tfdA and tfdB (10(2) to 10(3) gene copies g(-1) sediment) were only detected in sediments from contaminated areas of the aquifer. PCR-restriction fragment length polymorphism measurements demonstrated the presence of different populations of tfd genes, suggesting that the in situ herbicide degradation was caused by the activity of a heterogeneous population of phenoxy acid degraders. The number of Pseudomonas bacteria measured by either PCR or plating on selective agar media was higher in sediments subjected to high levels of phenoxy acid. Furthermore, high numbers of CFU compared to direct counting of 4',6-diamidino-2-phenylindole-stained cells in the microscope suggested an increased culturability of the indigenous microbial communities from acclimated sediments. The findings of this study demonstrate that continuous exposure to low herbicide concentrations can markedly change the bacterial community composition of a subsurface aquifer.

2,4-Dichlorophenoxyacetic Acid↗

PubMed1999

Detection and quantification of Salmonella in pure cultures using 5'-nuclease polymerase chain reaction.

Advances in detection and quantification assays based on nucleic acids conceivably will revolutionize the ability to quickly and specifically detect and quantify microorganisms in foods. Among these assays, the polymerase chain reaction (PCR) assay and the TaqMan PCR Detection System (Perkin-Elmer) probably are among the most promising. Since a 5'-nuclease PCR renders possible the automated and direct detection and quantification of PCR products (Holland et al., 1991. Proc. Natl. Acad. Sci. USA 88, 7276-7280), microorganisms in foods can be detected and quantified indirectly within a few hours through analysis of the microbial DNA or RNA sequences present. In the present report we have adapted a 5'-nuclease-based kit for the quantification of Salmonella.

Colony Count, Microbial↗

PubMed1998

An automated system for biocide testing on biofilms.

The paper presents and discusses a novel on-line real-time non-destructive continuous-flow system for biocide testing on industrial biofilms. This laboratory system is capable of monitoring changes in growth, accumulation and respiratory activity of biofilms in response to biocidal treatment. The system incorporates a fouling monitor for continuous measuring of the rate of biofilm accumulation (heat transfer resistance), a sensor for monitoring of microbial activity (oxygen meter for monitoring the rate of biofilm respiratory activity), and subsystems necessary for microbial life support and control of operation parameters. Examples of system operation and testing of oxidizing and non-oxidizing biocides are presented.

Biofilms↗

PubMed1998

The effect of essential oils of basil on the growth of Aeromonas hydrophila and Pseudomonas fluorescens.

Basil essential oils, including basil sweet linalool (BSL) and basil methyl chavicol (BMC), were screened for antimicrobial activity against a range of Gram-positive and Gram-negative bacteria, yeasts and moulds using an agar well diffusion method. Both essential oils showed antimicrobial activity against most of the micro-organisms examined except Clostridium sporogenes, Flavimonas oryzihabitans, and three species of Pseudomonas. The minimum inhibitory concentration (MIC) of BMC against Aeromonas hydrophila and Pseudomonas fluorescens in TSYE broth (as determined using an indirect impedance method) was 0.125 and 2% (v/v), respectively; the former was not greatly affected by the increase of challenge inoculum from 10(3) to 10(6) cfu ml-1. Results with resting cells demonstrated that BMC was bactericidal to both Aer. hydrophila and Ps. fluorescens. The growth of Aer. hydrophila in filter-sterilized lettuce extract was completely inhibited by 0.1% (v/v) BMC whereas that of Ps. fluorescens was not significantly affected by 1% (v/v) BMC. In addition, the effectiveness of washing fresh lettuce with 0.1 or 1% (v/v) BMC on survival of natural microbial flora was comparable with that effected by 125 ppm chlorine.

Acyclic Monoterpenes↗