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At least 973 records · Page 54Linked to original sources
PubMed1996

Bacterial colonization of bioabsorbable barrier material and periodontal regeneration.

The objective of the study was to evaluate bacterial colonization of the tooth-facing surface of bioabsorbable membranes and to determine its effect on the clinical outcome of membrane supported reconstructive periodontal surgery. Twenty systemically healthy subjects affected by chronic adult periodontitis were enrolled in the study. One non-furcation tooth site per patient, associated with an angular bony defect and a probing attachment loss of > 5 mm, was selected to be treated by means of a guided tissue regeneration procedure using a polyglicolactic membrane. Antibiotics (amoxicillin/clavulanate potassium 1 g per day) for 2 weeks were prescribed, in addition to the use of chlorhexidine for post-surgical plaque control. All patients were recalled once a week for 5 weeks for professional tooth cleaning. At 5 weeks sites with clinically exposed membranes underwent a second surgery to harvest residual barrier material which was analyzed by scanning electronic microscopic (SEM) for bacterial colonization. Sites with no membrane exposure at 5 weeks were allowed to heal without any other surgical intervention. Professional tooth cleaning and reinforcement of self-performed oral hygiene measures were given at 1 month intervals for the duration of the study. For each treated site the difference in probing attachment loss between baseline examination and a follow-up examination made 6 months after the second surgery was calculated. Gain of probing attachment was statistically (P < 0.001) greater in sites with no membrane exposure when compared to sites with partially exposed barrier material (4.2 +/- 0.5 vs. 3.3 +/- 0.6). The results of SEM analysis revealed that bacterial colonization was evident in all the microscopic fields of the exposed areas of the membranes. In the mid-part of the membranes 16 out of 39 microscopic fields (41%) demonstrated microbial colonization, while no bacteria-positive field was observed in the most apical portion of the membranes. Regression analysis indicated that gain in probing attachment level was negatively correlated to microbial colonization of the mid-part of the membranes. It was suggested the midportion of the tooth-facing surface of polyglicolactic membrane is a critical area for the healing process since its bacterial colonization was detrimental to the outcome of the GTR surgery.

Adult↗
PubMed1991

The behavior of selected microorganisms during the manufacture of high moisture Jack cheeses from ultrafiltered milk.

Whole milk was pasteurized and concentrated two times by ultrafiltration. Starter cultures, Lactococcus lactis ssp. cremoris and Lactococcus lactis ssp. lactis, were propagated in either reconstituted skim milk, two times UF retentate, or UF permeate, or a direct vat system was used for the starter culture. The cheese milk was simultaneously inoculated with starter culture and Pseudomonas fragi 4973, Staphylococcus aureus 196E, and Salmonella typhimurium var. Hillfarm. Control whole milk, UF control milk, inoculated whole milk, and inoculated UF milk were made into Monterey Jack cheese using traditional procedures. The process of cheese manufacture was followed by determination of pH, titratable acidity, and microbial population levels. The cheeses were stored for 6 mo and analyzed every month for percentage solids and microbial population levels. Generally, numbers of contaminant microbes increased at a similar rate during manufacture in all cheeses. During the 6-mo ripening period, bacterial starter culture population levels remained high, psychrotrophs declined slowly, Staphylococcus levels remained stable, and Salmonella populations decreased. No Staphylococcus enterotoxin was detected by reverse passive latex agglutination assay.

Animals↗
PubMed2000

Recalls of foods and cosmetics due to microbial contamination reported to the U.S. Food and Drug Administration.

In the U.S., food product recalls serve as an important intervention in stemming the consumption of food products contaminated with infectious disease agents. We summarize the number and nature of foods and cosmetics recalled as a result of microbial contamination reported to the U.S. Food and Drug Administration (FDA) for the period 1 October 1993 through 30 September 1998. During this period, microbial contamination of food and cosmetic products was the leading cause for recalls, accounting for a total of 1,370 recalls (36% of all products recalled). Listeria monocytogenes accounted for the greatest number of food products recalled because of microbial contamination, whereas Pseudomonas aeruginosa was the most common microbe associated with recalls of cosmetic products. Dairy products, followed by seafood and pastry items, were the types of products most often associated with recalls due to microbial contamination. The FDA was the entity most often responsible for detecting microbial contamination of foods and cosmetics (33% of all such recalls), followed by state regulatory agencies (24%), and manufacturers/retailers (21%). Nineteen percent of recalls were associated with at least one reported case of illness. Salmonella was the pathogen most often implicated in reports of illness associated with these recalled products.

Animals↗
PubMedDate not supplied

Airborne contamination during blow-fill-seal pharmaceutical production.

The routes of airborne contamination, during Blow-Fill-Seal (BFS) production, were studied using tracer gas, particles and bacteria. The prevention of airborne contamination, by the air shower at the point of fill, was effective (> 99.2% efficient). However, microbe-carrying particles could gain access, by deposition or air exchange, when the containers were cut open and before they shuttled under the protection of the air shower. The use of SF6 tracer gas demonstrated that when the air shower was not on, 50% of the air within the containers came from the area round the machine. When the air shower was switched on, only about 5% of the air came from the surroundings. Airborne microbial contamination of containers is in proportion to: the number of airborne microbes around the machine, the time the container is open, the neck area and the amount of air left within the container. The likely microbial contamination rate can be calculated from a model incorporating these variables. Microbial contamination of containers during BFS manufacturing is normally very low, but by increasing the naturally occurring bacteria in the air of the production rooms by about 100-fold, it was possible to verify the accuracy of this model. The contamination model agrees well with the observation that microbial contamination levels of between 1 in 10(5) and in 10(7) will be found when small containers (< 10 ml) are filled in conventionally ventilated rooms. To achieve similar contamination rates when filling of larger bottles, it is likely that unidirectional flow, or barrier technology will be required.

Air Microbiology↗
PubMed2000

Mixed starter cultures to control biogenic amine production in dry fermented sausages.

Several combinations of an amine-negative Lactobacillus sakei strain, along with proteolytic Staphylococcus carnosus or Staphylococcus xylosus strains, were used to study the influence of mixed starter cultures on biogenic amine production during the manufacture of dry fermented sausages. Changes in pH, water content, proteolysis, microbial counts, and biogenic amine contents were simultaneously examined in a spontaneously fermented batch and in three mixed starter-mediated batches. A double-controlled microbial charge initially inoculated as mixed starter culture of L. sakei and Staphylococcus spp. (all amine-negative strains) drastically reduced tyramine, cadaverine, and putrescine accumulation. No production of other aromatic amines such as histamine, phenylethylamine, or tryptamine was observed in any batch. The polyamines, spermine and spermidine, were found in raw materials and their levels decreased slightly in the spontaneously fermented batch. No correlation between proteolysis and biogenic amine production was observed. The use of proper technological conditions favoring starter development and the use of the raw materials with good hygienic quality make it possible to produce fermented sausages nearly free of biogenic amines.

Animals↗
PubMed2006

Inactivation of escherichia coli 0157:H7 and Salmonella on mung beans, alfalfa, and other seed types destined for sprout production by using an oxychloro-based sanitizer.

The efficacy of a stabilized oxychloro-based food grade sanitizer to decontaminate seeds destined for sprout production has been evaluated. By using mung bean seeds as a model system, it was demonstrated that the sanitizer could be used to inactivate a five-strain cocktail of Escherichia coli O157:H7 or Salmonella introduced onto beans at 10(3) to 10(4) CFU/g. Salmonella was more tolerant to stabilized oxychloro than was E. coli O157:H7, with sanitizer levels of >150 and >50 ppm, respectively, being required to ensure pathogen-free sprouts. The decontamination efficacy was also found to be dependent on treatment time (>8 h optimal) and the seed-to-sanitizer ratio (>1:4 optimal). Stabilized oxychloro treatment did not exhibit phytotoxic effects, as germination and sprout yields were not significantly (P > 0.05) different as compared with untreated controls. Although human pathogens could be effectively eliminated from mung beans, the aerobic plate count of native microflora on sprouts grown from treated seed was not significantly (P > 0.05) different from the controls. The diversity of microbial populations (determined through 16S rRNA denaturing gradient gel electrophoresis analysis) associated with bean sprouts was not significantly affected by the sanitizer treatment. However, it was noted that Klebsiella and Herbasprillum (both common plant endophytes) were absent in sprouts derived from decontaminated seed but were present in control sprouts. When a further range of seed types was evaluated, it was found that alfalfa, cress, flax, and soybean could be decontaminated with the stabilized oxychloro sanitizer. However, the decontamination efficacy with other seed types was less consistent. It appears that the rate of seed germination and putative activity of sanitizer sequestering system(s), in addition to other factors, may limit the efficacy of the decontamination method.

Chlorine Compounds↗
PubMed1996

The hygienic efficiency of conventional and inverted lamb dressing systems.

Aerobic plate counts (APC 37 degrees C and APC 25 degrees C) and Escherichia coli enumerations (Petrifilm) were used to determine sources of bacterial contamination during sheep dressing, determine the hygienic efficacy of hand wash and knife 'sterilization' procedures and compare the hygiene efficiency of conventional and inverted sheep dressing systems. The major slaughterline sources of microbial contamination were: fleece > workers' hands > faecal pellets > knife blades. Aerobic plate counts (APC 37 degrees C) exceeding log 4.4 cfu cm-2 were considered indicative of direct fleece contact, whereas E. coli numbers exceeding log 3.3 cfu cm-2 were considered indicative of direct faecal contact. A 44 degrees C water hand rinse removed 90% of the microbial contamination from workers' hands, but rinsed hands, particularly those contacting the fleece, still carried a microbial population exceeding log 4.0 cfu cm-2. A 44 degrees C rinse followed by an 82 degrees C water dip reduced the contamination on knife blades to less than log 3.0 cfu cm-2. Inverted dressing systems produced carcasses with a lower contamination level than conventional systems. With both systems little increase in contamination occurred after pelt removal. The areas of highest contamination were the forequarter region with inverted dressing and the hindquarter with conventional dressing. In both cases these regions are the sites where cuts are made through the skin. With both systems contamination around these cuts was entirely consistent with direct fleece contact resulting from 'rollback'.

Animals↗
PubMed2005

Microbiological survey of prepackaged pâté and ham in New Zealand.

AIMS: To gauge the effectiveness of pâté and ham manufacturers' management of the microbial safety and quality of their products. METHODS AND RESULTS: A survey of 60 batches of prepackaged pâté showed that 41.7% of the batches had aerobic plate counts (APC) exceeding 10(5) CFU g(-1), one of pâté sample contained a Bacillus cereus count of >5000 CFU g(-1) and another contained 1700 CFU g(-1) of Listeria monocytogenes. No other pathogens were isolated from any of the samples. The survey of prepackaged ham showed that only 1% (1/104) of the ham samples were positive for L. monocytogenes (50 CFU g(-1)). CONCLUSIONS: The presence of microbial hazards in these foods has generally declined since the early 1990s in New Zealand. Noncomplying APC levels may be due to an over-estimation of product shelf life or poor food handling practices during manufacture. SIGNIFICANCE AND IMPACT OF THE STUDY: Few of the samples tested contained pathogens at significant levels. The prevalences of L. monocytogenes in pâté and ham were low. The presence of 1700 CFU g(-1) of L. monocytogenes in a pâté sample indicates that occasionally, the population can be exposed to levels of L. monocytogenes above the zero tolerance level set in New Zealand.

Bacillus cereus↗
PubMed1995

Formation of organic cadmium by marine microorganisms.

This research was designed with a view to finding out whether or not there is a microbial or spontaneous transformation of inorganic cadmium into a highly toxic organic derivative of this metal by microorganism obtained from the Eastern Mediterranean marine environment. Sterile and nonsterile marine bottom sediment samples were incubated at ambient temperature for different time intervals, under aerobic and anaerobic conditions, with different concentrations of CdCl2, and the medium, the atmosphere in the incubation flasks, and the sediments were assayed for their organic cadmium contents. The results were: (a) There was microbial growth in all systems containing up to 250 micrograms cadmium per milliliter of growth medium; however, with higher concentrations a complete growth-inhibition was observed. (b) Organic cadmium was found in the bottom sediments, at all cadmium levels permitting considerable microbial growth, but not in the systems' atmospheres or in the liquid growth media. (c) Under aerobic conditions higher levels of organic cadmium were found than in the anaerobic systems. (d) The microorganisms occurring in the different experimental systems were isolated and identified. The predominating species in all systems were bacteria.

Bacteria, Aerobic↗
PubMed1995

A microbiological and immunological study of endodontic-periodontic lesions.

The microflora and humoral immune response in tissue from the periodontal pockets and root canals of five teeth with endodontic-periodontic lesions were examined. We found more microbes in the periodontal pockets than in the root canals. The flora in the periodontal pockets was dominated by rods and motile organisms, whereas that in the root canals was largely rods and cocci. We detected no spirochetes in the root canals. The cultivable microflora in the periodontal pockets comprised a high number of different species of bacteria, whereas those in the root canals included only a small number of species. There was no correlation between microbial isolates and antibody titer in the apical tissues or periodontal pockets. We conclude from these studies that the microflora of infected root canals is simple and limited, and that the local humoral immune response does not seem to affect the pathogenesis of disease directly.

Antibodies, Bacterial↗
PubMed2005

Feasibility study of bioremediation of a drilling-waste-polluted soil: stimulation of microbial activities and hydrocarbon removal.

The objective of this study was to determine the feasibility of bioremediation as a treatment option for an aged and chronically polluted drilling waste soil located at the Southeast of Mexico. The polluted drilling-waste site with a mean total petroleum hydrocarbon concentration (TPHs) of 39,397 +/- 858 mg/kg was treated with one dose of a nutrient-surfactant commercial product at 40 mg/kg soil and two doses of H2O2 (50 and 100 mg H2O2/kg soil). In this study, the parameters that were monitored include soil respiration, heterotrophic and hydrocarbon-degrading bacteria as biological indicators, catalase and dehydrogenase activities, and TPHs degradation as decontamination parameters. The results demonstrated that the microbial activities can be stimulated in a polluted drilling-waste site by the addition of H2O2 and commercial product, thereby resulting in increasing TPHs degradation. These aspects must be taken into account when biodegradation studies involve the application of a commercial product.

Analysis of Variance↗
PubMed2005

Establishment of minimum operational parameters for a high-volume static chamber steam pasteurization system (SPS 400-SC) for beef carcasses to support HACCP programs.

A static chamber steam pasteurization unit (SPS 400-SC()) was installed in a high-volume commercial beef slaughter facility. The SPS 400-SC consists of a three-phase carcass treatment cycle of water removal, steam pasteurization, and water chilling. Seven chamber temperatures (71.1, 73.9, 76.7, 79.4, 82.2, 85.0, and 87.8 degrees C) were evaluated at the midline area of pre-rigor beef carcasses. For each temperature evaluated, 20 carcass sides were randomly selected and aseptically sampled by tissue excision immediately before and after steam pasteurization to determine total aerobic bacteria, Enterobacteriaceae, generic E. coli, and total coliform populations. The 87.8 and 85.0 degrees C treatment temperatures were highly effective at reducing total aerobic bacterial populations, with log(10) reductions of 1.4 and 1.5 CFU/cm(2), respectively, from pretreatment mean population levels of 1.7 and 1.9 log10 CFU/cm(2). These temperatures also reduced Enterobacteriaceae, total coliforms, and generic E. coli to undetectable levels (<0.4 CFU/cm(2)) on all carcasses sampled. Treatment at 82.2 was marginally effective at reducing bacterial populations, while 71.1, 73.9, 76.7, and 79.4 degrees C treatments were ineffective at reducing microbial populations. In a Hazard Analysis Critical Control Points (HACCP)-based system employing steam pasteurization of carcasses as a critical control point, a critical limit of 85.0 degrees C as a minimum chamber temperature should be established, with a targeted operating temperature of 87.8 degrees C providing optimum antimicrobial activity.

Abattoirs↗
PubMed1997

Experimental endocarditis induction and platelet aggregation by Streptococcus anginosus, Streptococcus constellatus and Streptococcus intermedius.

A total of 18 'Streptococcus milleri' strains including the ATCC type strains of Streptococcus anginosus, Streptococcus constellatus and Streptococcus intermedius were compared with Streptococcus oralis ATCC10557 for their ability to induce infective endocarditis in catheterized rats. Three days after intravenous injection of 10(8) colony-forming units all 8 S. anginosus strains tested produced infective vegetations and bacteremia in almost all rats whereas 5 S. constellatus strains and the S. oralis strain produced infective vegetations and bacteremia less frequently and 5 S. intermedius strains only occasionally. The vegetations infected with the S. anginosus strains harbored microbial cells in significantly higher numbers that those with the other strains. No strong correlation was found between the endocardial infectivity and platelet-aggregating capacity of these strains. The platelet-aggregating strains were members of the Lancefield groups F and G or ungroupable but not of group A or C.

Animals↗
PubMed2001

Current trends in predictive modelling of microbial lag phenomena.

This paper summarises recent trends in predictive modelling of microbial lag phenomena. The lag phase is approached from both a qualitative and quantitative point of view. Major modelling approaches and experimental results are critically assessed. This review mainly focuses on the influence of temperature and culture history on the lag phase during growth of bacteria.

Bacteria↗
PubMedDate not supplied

Environmental microbial challenges to an aseptic Blow-Fill-Seal process--a practical study.

A Blow-Fill-Seal machine, set to aseptically fill sterile liquid TSB medium into 20 ml plastic containers, was subjected to a series of environmental microbial challenges in order to evaluate the effects of the room environment, and of the actions of persons in the room, on the sterility of the product. Despite a series of relatively severe stresses to the system, none of the units filled (approximately 44,000) were found, following incubation, to display growth.

Air Microbiology↗
PubMed1998

In vivo early plaque formation on pure titanium and ceramic abutments: a comparative microbiological and SEM analysis.

A lack of information exists about the influence of different implant abutment materials on bacterial colonization and its role in the development of perimplantar infections. In order to study these aspects, removable acrylic devices, harboring samples of titanium and novel ceramic abutments (Nobel Biocare) were adapted to the molar-premolar region in 2 mandibular quadrants of 4 volunteers. Samples of each material were collected at 6 and 24 h, 7 and 14 days. Samples were observed by scanning electron microscopy and bacterial counts were made by means of ATP detection and direct plate count. The electron micrographs demonstrated that the bacteria colonization was already present after 6 h of presence in the oral cavity. After 24 h, both the materials were covered by several layers of bacterial cells. No differences in microbial colonization were observed between titanium and ceramic samples. The microbiological analysis confirmed the presence of relevant amounts of microbial cells on the tested samples. The maximum of colonization was achieved after 24 h in the oral cavity and the bacterial counts remained constant over the 14 day period. No significant differences were observed between the two materials analyzed in this study. In addition, ATP-bioluminescence technology was demonstrated to be a suitable system to evaluate bacterial colonization in the oral cavity.

Adenosine Triphosphate↗
PubMed1989

Keeping quality of vacuum-packed smoked sardine fillets: microbiological aspects.

The effect of mixed smoking (2 h at 30 degrees C and 45 min at 75 degrees C was studied on the keeping quality of lean and fatty sardine fillets from fish caught in the Mediterranean Sea in March and June, respectively. Raw material for smoking included both fresh and frozen sardine fillets. Microbiological and sensory analyses were performed over the storage period, which lasted for 120 days at 0 +/- 1 degrees C. Smoking reduced the viable microbial flora values from 3-5 x 10(4) cfu/g to 2 x 10(2) cfu/g. The antimicrobial action of smoking, combined with that of vacuum packaging, had the effect of producing a gram-positive flora made up mainly of lactic acid bacteria. A practical consequence of this was to extend the shelf life of the smoked sardines for a period of 4 months. Frozen storage of samples at -18 degrees C for 6 months prior to smoking affected the behaviour of the microbial flora during cold storage at 0 degrees C, but did not affect the behaviour of the flora over a period of 3 months frozen storage, since the initial numbers of bacteria decreased and microbial growth was retarded. Furthermore, at the end of the storage period, the number of bacteria in the samples of frozen fatty sardines were higher than in the samples of frozen lean sardine. Physical conditions, therefore appear to exert an influence on bacterial growth. Sulphite-reducing Clostridia were not detected during the storage period.

Animals↗