Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Colony Count, Microbial”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,549 records · Page 86Linked to original sources
PubMed1997

Bacterial colonization of mineralized and completely demineralized dentine in situ.

The changing environment in a developing root lesion may result in a succession of the microbial flora in the dentine. As demineralization proceeds, the collagenous matrix is exposed, which could be conducive to the growth of specific microorganisms. In this study both sound and completely demineralized dentine were placed together in the partial prothesis of 8 individuals to test whether the type of substrate influenced the composition of the bacterial flora. After 6 weeks the degradation of the collagenous matrix, the demineralization of the dentine and the microbial composition were assessed. The collagen loss varied between 0 and 69 wt%. Mineral loss from the originally sound dentine specimens ranged from virtually none to complete demineralization. Percentages of total streptococci, mutans streptococci, Actinomyces and lactobacilli isolated from both dentinal substrates did not differ significantly. The percentage of lactobacilli in the dentine specimens was positively correlated to the lesion depth. The percentage of Actinomyces species was significantly higher in both the dentine specimens that had been demineralized in vitro and those that were found to be completely demineralized in situ compared to the partially demineralized dentine specimens. In vitro, no collagenolytic activity of the predominant flora isolated from both dentinal substrates could be shown.

Actinomyces↗
PubMed2005

Comparison of the chlorine inactivation of Yersinia enterocolitica in chlorine demand and demand-free systems.

Inactivation of Yersinia enterocolitica by chlorine (0.6 to 20 ppm) was investigated in distilled water and in tryptic soy broth (TSB, 0.015%) at different temperatures (4, 20, and 40 degrees C). In distilled water, chlorine inactivation of Y. enterocolitica was enhanced by increasing the temperature from 4 to 20 degrees C, and survival curves were described by a model that assumed first-order kinetics followed by tailing in which the microbial concentration remained constant. The presence of TSB increased chlorine resistance of Y. enterocolitica, and survival curves were concave downward. These survival curves were described by a model based on the Weibull distribution. Chlorine decay in distilled water was independent of temperature and of the initial concentration of available chlorine and was modeled by first-order reaction kinetics. Chlorine decay in TSB was independent of the initial chlorine concentration but depended on the treatment temperature and was modeled by the addition of two first-order decay equations. The increased resistance of Y. enterocolitica to chlorine in TSB was not due only to the chlorine demand by the TSB components. These components protected Y. enterocolitica cells from the antimicrobial effect of chlorine.

Chlorine↗
PubMed2003

Factors associated with ileal mucosal morphology and inflammation in patients with ileal pouch-anal anastomosis for ulcerative colitis.

PURPOSE: Pouchitis has been associated with abnormal bacterial flora responding to antibiotics. Dietary factors may play a role in modifying the qualitative and quantitative components of the microflora. We evaluated interactions between nutritional factors, fecal and mucosal bacterial flora, and mucosal morphology in patients with a history of pouchitis compared with patients with optimal outcome at least five years after ileal pouch-anal anastomosis for ulcerative colitis. METHODS: Thirty-two patients were enrolled in the study: 11 (7 males; mean age, 49.8 years) with optimal outcome and 21 (11 males; mean age, 47.3 years) with pouchitis history. A seven-day food diary was recorded, endoscopy performed, and biopsies taken from the pouch for histology, mucin staining, and bacterial culture. Fresh fecal samples were quantitatively cultured, and fecal bile acids analyzed by gas-liquid chromatography. RESULTS: No differences existed in mean nutrient intake, composition of fecal bile acids, or microbial tissue biopsy cultures between the groups with and without pouchitis. Those with optimal outcome tended to have more benign disease course of ulcerative colitis than patients with pouchitis. In those patients, fecal concentrations (log10 colony-forming unit/g) of anaerobes and aerobes were significantly higher (P = 0.007). Degree of villous atrophy and colonic metaplasia were both associated with fecal anaerobic flora. Low intake of lactose was associated with sulfomucin predominance. A negative correlation existed between fecal aerobes and dietary lactose consumption. CONCLUSIONS: A higher total load of fecal anaerobic bacterial flora is strongly associated with degree of colonic metaplasia, villous atrophy, and inflammation activity after surgery for ulcerative colitis. An association existed between dietary lactose, fecal bacteria, and pouch morphology. Lactose may have prebiotic properties.

Adult↗
PubMed2003

Bacteria and disinfection byproducts in water from southern Mexico City.

Disinfection byproducts and microorganisms present in drinking water may have deleterious effects on human health. The authors examined bacterial indicators (enterobacteria and Helicobacter pylori [H. pylori]), physicochemical parameters, and trihalomethane (THM) levels to conduct a water quality evaluation in Mexico City, where little is known about disinfection byproducts and microbial counts. Analyses were performed by standard membrane filtration for the enumeration of total coliforms, fecal coliforms, fecal streptococci, and Vibrio species. Other testing consisted of polymerase chain reaction (PCR) for H. pylori, physicochemical parameters by selective electrodes, and THMs by head-space with the use of a gas chromatograph. Indicator bacteria and enterobacteria were detected in 23% of samples, with significant differences between total coliforms, fecal coliforms, and fecal streptococci before and after chlorination. H. pylori was detected in 69% of samples prior to chlorination and 57% postchlorination. THM levels were < 200 microg/l. Chlorine concentrations ranged from < 0.05 mg/l to 35 mg/l. Disinfection at the well does not ensure good water quality for the Mexico City population. The next step will be the monitoring of water quality in the distribution system that supplies dwellings, as well as water obtained directly from the tap.

Chlorine↗
PubMed2000

Incorporating model uncertainties along with data uncertainties in microbial risk assessment.

Much research on food safety has been conducted since the National Food Safety Initiative of 1997. Risk assessment plays an important role in food safety practices and programs, and various dose-response models for estimating microbial risks have been investigated. Several dose-response models can provide reasonably good fits to the data in the experimental dose range, but yield risk estimates that differ by orders of magnitude in the low-dose range. Hence, model uncertainty can be just important as data uncertainty (experimental variation) in risk assessment. Although it is common in risk assessment to account for data uncertainty, it is uncommon to account for model uncertainties. In this paper we incorporate data uncertainties with confidence limits and model uncertainties with a weighted average of an estimate from each of various models. A numerical tool to compute the maximum likelihood estimates and confidence limits is addressed. The proposed method for incorporating model uncertainties is illustrated with real data sets.

Colony Count, Microbial↗
PubMed2004

High-throughput techniques for analyzing complex bacterial communities.

A more complete understanding of microbial diversity and the environmental processes they control will require much more than a biotic inventory. It will require a deeper understanding of the basic features of systems organization and inter-population interactions. Communities, not total biomass, control net process rates driving the biogeochemical cycles sustaining the biosphere. Although the general patterns of macroorganismal diversity are relatively well known, spatial and temporal patterns of microorganismal diversity are essentially unknown. Having tools capable of resolving these patterns is a prerequisite to developing an understanding of the relationship between community structure and function. This talk discusses conceptual and technical developments that now provide the framework for systematically resolving temporal and spatial patterns of microorganisms and relating those patterns to processes at local and system levels. Of particular emphasis will be ongoing studies using highly parallel analyses with DNA microarrays for intensive monitoring of microbial populations in environmental systems. Although microarray technology is reasonably well established for studies of model organisms in well-defined laboratory settings, the application of this technology to environmental systems of uncharacterized diversity imposes additional demands on implementation; in particular, the requirement for optimized discrimination between target and non-target nucleic acids in complex, and undefined, mixtures. To increase the resolving power (information content) of our DNA microarray format, we are investigating the use of thermal dissociation of hybrids immobilized on individual array elements to resolve target and non-target sequences that differ by a single nucleotide. These studies, combined with specialized algorithms for optimizing the readout of the microarray should serve for informed environmental application. Initial studies have validated the general approach for analyses of sediment systems.

Bacteria↗
PubMed2001

Estimating the frequency of high microbial counts in commercial food products using various distribution functions.

Industrial microbial count records usually form an irregular fluctuating time series. If the series is truly random or weakly autocorrelated, the fluctuations can be considered as the outcome of the interplay of numerous factors that promote or inhibit growth. These factors usually balance each other, although not perfectly, hence, the random fluctuations. If conditions are unchanged, then at least in principle the probability that they will produce a coherent effect, i.e., an unusually high (or low) count of a given magnitude, can be calculated from the count distribution. This theory was tested with miscellaneous industrial records (e.g., standard plate count, coliforms, yeasts) of various food products, including a dairy-based snack, frozen foods, and raw milk, using the normal, log normal, Laplace, log Laplace, Weibull, extreme value, beta, and log beta distribution functions. Comparing predicted frequencies of counts exceeding selected levels with those actually observed in fresh data assessed their efficacy. No single distribution was found to be inherently or consistently superior. It is, therefore, suggested that, when the probability of an excessive count is estimated, several distribution functions be used simultaneously and a conservative value be used as the measure of the risk.

Colony Count, Microbial↗
PubMed2000

In vitro evaluation of the retention of three species of pathogenic microorganisms by three different types of toothbrush.

The retention and survival of microorganisms on toothbrushes pose a threat of recontamination for certain patients at risk. In order to measure the influence of brush design and optimize the choice of toothbrush model for complementary studies, the in vitro retention of three microbial species (Porphyromonas gingivalis ATCC 33277, Streptococcus mutans ATCC 25175 and Candida albicans ATCC 26555) was evaluated for three types of toothbrush. Two series of standardized experiments were carried out for each brush and microorganism. The first series tested the retention of the microorganisms on the head portion of the brush, while the second measured retention on the head of the brush and the part of the handle inserted in the mouth during brushing. For each series, the microorganisms were counted at T0 and T24 (after storage of the brushes at room temperature for 24 h). Depending on the microorganism studied, from 0.2% to 2% of the initial inoculum was retained on the brush. The number detected increased with the size of the exposed area. After 24 h, P. gingivalis and S. mutans were found on only one type of brush. C. albicans survived on all three. These results confirm that microorganisms can quickly colonize toothbrushes.

Candida albicans↗
PubMed2001

Quantitative investigation of the effects of chemical decontamination procedures on the microbiological status of broiler carcasses during processing.

The effects of elevated chlorine concentrations (25 ppm) added to water in the final carcass washing equipment on total viable counts (TVCs 22 degrees C) and Escherichia coli and Enterobacteriaceae levels on poultry carcasses were investigated. Mean TVC counts on neck skin samples were significantly reduced when pre-evisceration and postwash samples were compared with log10 4.98 to 4.52 CFU/g recovered, respectively (P < or = 0.05). No significant reductions in TVC counts were observed in control samples at corresponding sampling points subjected to wash water containing 1 to 2 ppm chlorine. E. coli and Enterobacteriaceae counts were not significantly altered following final carcass washing in the processing plant. A second trial assessed the microbial decontamination capabilities of sodium triphosphate (TSP) on broiler carcasses. Neck skin samples from carcasses were obtained before final washing (control), following a 15-s dip in potable water and after dipping in a 10% TSP solution (pH 12) for 15 s. Reductions in E. coli and Enterobacteriaceae counts were all statistically significant for both water and TSP-treated samples when compared with corresponding controls (P < or = 0.01). The TSP treatment resulted in higher reductions of log10 1.95 and 1.86/g for E. coli and Enterobacteriaceae, respectively. In contrast, reductions of log10 0.37 and 0.3 l/g were observed for E. coli and Enterobacteriaceae counts when water-dipped carcasses were compared with corresponding controls. Significantly, Salmonella was not detected in any of the TSP-treated carcasses, while log10 1.92 and 1.04/g were found in control and water-dipped samples, respectively. Thermophilic Campylobacter counts were significantly lower in both treatment groups when compared with corresponding controlsresulting in log10 0.55 and 1.71/g reductions for water- and TSP-dipped carcasses, respectively (P < or = 0.01).

Animals↗
PubMedDate not supplied

[Distribution and physiology of microorganisms in petrochemical oily sludge of plant].

The occurrence, vertical distribution, and the physiological state of microorganisms in a petrochemical oily sludge deposit were studied. The total number and the number of viable microbial cells at depths of 0.2 and 3 m were about 10 and 10(8) cells/g dry wt. sludge. Most microbial cells taken from the middle (1 m deep) and the bottom (3 m deep) sludge horizons showed a delayed colony-forming ability, which suggested that the cells occurred in a hypometabolic state. The relative number of microaerobic denitrifying microorganisms steeply increased with depth. The amount of microorganisms tolerant to 3, 5, and 10% NaCl and capable of growing at 7 and 40 degrees C varied from 10(2) to 10(8) CFU/g dry wt. sludge. Petrochemical oily sludge was found to maintain the growth of heterotrophs, among which the degraders of oily sludge and ten different individual polycyclic aromatic hydrocarbons were detected. The occurrence of highly adaptable microorganisms with an adequate metabolic potential in the petrochemical oily sludge deposit implies that its bioremediation is possible without introducing special microorganisms.

Bacteria↗
PubMed2006

Protozoan grazing increases mineralization of naphthalene in marine sediment.

Bacterial decomposition of organic matter is frequently enhanced when protozoa are present. Various mechanisms have been proposed to account for this phenomenon, including effects associated with grazing by protozoa (such as increased recycling of limiting nutrients, removal of senescent cells, or reduction of competition among bacteria) and indirect effects of grazers (such as excretion of bacterial growth factors). Few studies have examined the role of protozoa in bacterial degradation of xenobiotic compounds in sediment containing a natural community of microbes. The effect of protozoa on mineralization of naphthalene was investigated in this study. Laboratory experiments were conducted using field-contaminated estuarine sediment, with the indigenous microbial populations. Mineralization of naphthalene was up to four times greater in treatments with actively grazing protozoa than in treatments containing the grazing inhibitor cytochalasin B. Control experiments confirmed that the grazing inhibitor was not toxic to ciliates but did prevent them from grazing. The grazing inhibitor did not affect growth rates of a mixed culture of sediment bacteria or a pure polycyclic-aromatic-hydrocarbon-degrading strain. Once grazing had been inhibited, supplementing treatments with inorganic N and P, glucose, or additional protozoa failed to stimulate naphthalene mineralization. Naphthalene-degrading bacteria were four to nine times less abundant when protozoan grazing was suppressed. We suggest that protozoa enhance naphthalene mineralization by selectively grazing on those sediment bacteria that ordinarily would outcompete naphthalene-degrading bacteria.

Animals↗
PubMed2006

New developments in the study of the microbiota of naturally fermented sausages as determined by molecular methods: a review.

The microflora of different types of fermented sausages has been defined by isolation and biochemical identification of the microorganisms commonly found in these products. It is generally agreed that the main microbial groups involved in such products are lactic acid bacteria and coagulase-negative cocci. In addition, and depending on the product, other groups may play a role, such as yeasts and enterococci. Since it appears that the types of microbial groups, or even the specific strains of a given microbial group, that dominate the fermentation, significantly affect the organoleptic profile of the final product, there is an increasing interest in the description of the microbiota that are found in different fermented sausages. More recently, new tools, based on molecular methods, allowing fast and unequivocal identification of strains, isolated from fermented sausages, became available. These methods have been successfully applied and, in general, biochemical and molecular identification compared well. However, new information comes to light when molecular methods are applied to DNA and/or RNA extracted directly from sausages. This approach eliminates problems related to traditional isolation. This review deals with the recent findings and results of the application of molecular methods, in a culture-dependent and culture-independent manner, on the study of the microflora of fermented sausages.

Animals↗
PubMed2004

Effect of the antibacterial activity of pig pancreatic juice on human multiresistant bacteria.

INTRODUCTION: The role of the exocrine pancreas in regulating gut microflora colonization is unclear. The main objective in the current study was to assess the effect of pancreatic fluid on the growth of pathogenic bacteria and fungi. METHODS: The antibacterial activity of pure pig pancreatic juice collected from catheterized, healthy, conscious, and anesthetized pigs was investigated with multiresistant microbial isolates and nonpathogenic strains. Studies were performed on pathogenic bacterial and fungi as well as lactic acid bacteria and reference strains. RESULTS: Pancreatic juice was effective (P < 0.01) against multidrug resistant bacterial pathogens, whereas lactic acid bacteria were insensitive. The antibacterial action was independent of pancreatic juice proteolytic activity. The in vitro antibacterial properties of pancreatic juice last for several hours. Data suggest that broth composition may modulate the intensity of pancreatic juice antibacterial activity. CONCLUSIONS: Pancreatic juice antibacterial activity may be an important factor in limiting the colonization of pathogenic bacteria in the gastrointestinal tract. We postulate that observed antibacterial activity of the pancreatic juice could play an important role as one of the factors of innate immunity.

Animals↗
PubMed2003

Antimicrobial effect of 2% sodium hypochlorite and 2% chlorhexidine tested by different methods.

The objective of this study was to analyze the antimicrobial effect of 2% sodium hypochlorite (NaOCl) and 2% chlorhexidine (CHX) by agar diffusion test and by direct exposure test. Five microorganisms: Staphylococcus aureus, Enterococcus faecalis, Pseudomonas aernginosa, Bacillus subtilis, Candida albicans, and one mixture of these were used. These strains were inoculated in brain heart infusion (BHI) and incubated at 37 degrees C for 24 h. For the agar diffusion test (ADT), 18 Petri plates with 20 ml of BHI agar were inoculated with 0.1 ml of the microbial suspensions, using sterile swabs that were spread on the medium, obtaining growth injunction. Fifty-four paper disks (9 mm in diameter) were immersed in the experimental solutions for 1 min. Subsequently, three papers disks containing one of the substances were placed on the BHI agar surface in each agar plate. The plates were maintained for 1 h at room temperature, and then incubated at 37 degrees C for 48 h. The diameter of microbial inhibition was measured around the papers disks containing the substances. For the direct exposure test, 162#50 sterile absorbent paper points were immersed in the experimental suspensions for 5 min, and were then placed on Petri plates and covered with one of the irrigant solutions, or with sterile distilled water (control group). After intervals of 5, 1 0 and 30 min, the paper points were removed from contact with the solutions and individually immersed in 7 ml of Letheen Broth, followed by incubation at 37 degrees C for 48 h. Microbial growth was evaluated by turbidity of the culture medium. A 0.1 ml inoculum obtained from the Letheen Broth was transferred to 7 ml of BHI, and incubated at 37 degrees C for 48 h. Bacterial growth was again evaluated by turbidity of the culture medium. Gram stain of BHI cultures was used for verification of contamination and growth was determined by macroscopic and microscopic examination. The best performance of antimicrobial effectiveness of NaOCI was observed in the direct exposure test, and of CHX was observed in the agar diffusion test. The magnitude of antimicrobial effect was influenced by the experimental methods, biological indicators and exposure time.

Agar↗
PubMed2003

Direct-fed microbial supplementation on the performance of dairy cattle during the transition period.

The influence of a direct-fed microbial (DFM) on the prepartum period and the effects on production performance during the postpartum period was investigated using 64 multiparous Holstein cows. Two close-up dry cow diets were fed to two groups of 32 cows each starting 21 d precalving as follows: 1) no DFM and 2) DFM. Post-calving cows were fed a lactation ration with or without DFM supplementation.The direct-fed microbial (DFM) supplement contained 2 × 109 viable yeast cells and 5 × 109 cfu of bacteria (Enterococcus faecium) per cow per day, top dressed in a 90-g supplement [corrected].The DMI during the prepartum period was not affected by DFM supplementation. During the postpartum period, DMI, milk yield, and milk protein content were higher for cows receiving DFM supplementation compared with no DFM. Blood glucose and insulin levels were higher and NEFA levels were lower for cows receiving DFM during the postpartum period. These data suggest that targeted DFM supplementation increased DMI and milk production postpartum. Blood metabolite information would suggest this response was associated with more glucose being made available and less fatty acids being mobilized from lipid stores.

Animals↗
PubMed2005

Shelf-life extension of refrigerated Mediterranean mullet (Mullus surmuletus) using modified atmosphere packaging.

The present work evaluated the quality and freshness characteristics and the effect of modified atmosphere packaging (MAP) on the shelf-life extension of refrigerated Mediterranean mullet using microbiological, biochemical, and sensory analyses. Fresh open sea red mullet (Mullus surmuletus) were packaged in four different atmospheres: M1, 10%/20%/70% (O2/ CO2/N2); M2, 10%/40%/50% (O2/CO2/N2); M3, 10%/60%/30% (O2/CO2/N2); identical fish samples were packaged in air. All fish were kept under refrigeration (4 +/- 0.5 degrees C) for 14 days. Of the three gas atmospheres, the 10%/40%/50% (M2) and 10%/ 60%/30% (M3) gas mixtures were the most effective for inhibiting growth of aerobic microflora in mullet samples until day 10 of refrigerated storage. H2S-producing bacteria and pseudomonads were part of the mullet microflora and their growth was partly inhibited under MAP conditions. Between these two bacterial groups, H2S-producing bacteria (including Shewanella putrefaciens) were dominant toward the end of the storage period, regardless of the packaging conditions. Brochothrix thermosphacta and lactic acid bacteria were found to be members of the final microbial flora of MAP and air-packaged mullet, whereas the Enterobacteriaceae population was lower than other bacterial groups. Of the chemical freshness indices determined, thiobarbituric acid values were variable in mullet samples irrespective of packaging conditions indicative of no specific oxidative rancidity trend. Based on sensorial data and aerobic plate count, trimethylamine nitrogen and total volatile basic nitrogen limit values in the range of ca. 15 to 23 and 52 to 60 mg N/100 g of fish muscle were obtained, respectively, for mullet packaged under modified atmosphere and air. Sensory analyses (odor and taste attributes) showed that the limit of sensorial acceptability was reached after ca. 6 days for the samples packaged in air, 8 days for the M1 and M3 samples, and after 10 days for the M2 samples. Respective shelf-life extension for fresh whole mullet was ca. 2 days (M1 and M3 gas mixtures), and 4 days (M2 gas mixture).

Animals↗
PubMed2006

Characterization of the microbial flora in disinfecting footbaths with hypochlorite.

Change or disinfection of footwear are measures to prevent cross contamination between areas with low and high hygienic levels in the food industry. The efficacy of disinfecting footwear is not well documented. Samples of used disinfectant and from swabbing of corners after draining were taken from disinfecting footbaths containing chlorine in four Norwegian cheese factories. Bacteria were present in 9 of 12 footbaths and more positive samples were found from swab samples than from used disinfectant. The microbial flora in footbaths varied between the dairies. In two dairies, the flora was dominated by Pseudomonas spp. and Acinetobacter spp., respectively. In the third dairy, both Bacillus spp. and Staphylococcus spp. were present and in the fourth dairy, the flora was diverse (Acinetobacter sp., Enterococcus faecalis, Klebsiella pneumoniae, and Bacillus sp.). The strains were not resistant to the recommended user concentration of chlorine in bactericidal suspension or surface tests. The degree of attachment to plastic varied between strains and species and bacteria attached to surfaces were in general more resistant than suspended bacteria. The results of the survey indicated that disinfecting footbaths containing chlorine may act as contamination sources in food factories and should not be used without regular hygienic monitoring.

Bacteria↗
PubMed2000

Measurement of bacterial growth potential in a reclaimed water.

The objectives of this paper are to show a bio-assay method using direct total microbial count (DTMC) and to demonstrate the applicability of this method to reclaimed water for evaluating its potential of bacterial growth. We have applied our method to four types of reclaimed water, measuring the time course of DTMC and dissolved organic carbon in a bio-assay process. The experimental findings are summarised as follows: 1) By regulating organic carbon, bacteria growth could be controlled. 2) Reduction of the initial concentration of bacteria was effective to delay their growth, but this operation could not control their maximum level. This implies that the retention time of the storage and distribution system of reclaimed water should be considered in design and operation of the disinfection process. 3) Ozonation increased the growth potential. Carbon adsorption process reduced it, but the ozone plus carbon adsorption process could not improve the biological stability. 4) A linear relationship between DTMC and biodegradable organic carbon has been observed, the gradient of this linear correlation, however, depended on the source of reclaimed water.

Colony Count, Microbial↗