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Results for “Total Microbial Load”

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PubMed1998

ADRF Trebitsch Scholarship. The microbial contamination of toothbrushes. A pilot study.

Ten individuals were each supplied with a new toothbrush of the same type and brand, together with identical tubes of fluoridated toothpaste. After a three-week period, during which subjects were asked to follow their usual oral hygiene practices, the toothbrushes were collected and assayed for microbial contamination using a range of selective growth media. The total microbial load per toothbrush was found to be 10(4) to 10(5) colony forming units. Staphylococci were found on all toothbrushes and streptococci on all but one. These two genera were also quantitatively dominant. Candida, corynebacteria, pseudomonads and coliforms were identified in 70, 60, 50 and 30 per cent of toothbrushes, respectively. However, mutans streptococci, lactobacilli and black-pigmented Gram-negative anaerobic rods were not detected on any of the toothbrushes. For each individual, information on variables such as toothbrush rinsing practices and post-brushing storage methods and environment was collected. No obvious relationship between such variables and microbial load was apparent but it is suggested that more extensive studies are needed, taking into account additional parameters such as age and degree of toothbrush wear and the use of pre-brushing mouthwashes.

Adult↗

PubMed1991

Use of synthetic oligonucleotide DNA probes for identification and direct detection of Bacteroides forsythus in plaque samples.

Oligonucleotide DNA probes complementary to the hypervariable region of the 16S rRNA of Bacteroides forsythus were tested for their specificity and sensitivity against reference and clinical isolates of 73 different species of bacteria. The probes were used to detect the organism directly from nucleic acid extracts of subgingival plaque samples, and the results were compared with results of detection by culture methods. The data demonstrate that the probes are very specific (100%) and sensitive (100% when they are compared with those obtained by the culture method) and could reliably detect the organism in plaque samples. When a probe to a conserved region of the 16S rRNA (UP9A) was used to estimate the quantity of bacteria present in plaque samples, it gave results comparable to those of culture methods. The data suggest that total microbial load may be a parameter in periodontal disease.

Bacteroides↗

PubMed1997

Short-chain carboxylic acid concentration in human gingival crevicular fluid.

Short-chain carboxylic acids (e.g., lactic acid, propionic acid, butyric acid) are metabolic by-products of bacterial metabolism which can accumulate in the gingival crevice. It is of no small consequence, therefore, that 1- to 5-mM concentrations of these acids exhibit significant biological activity, including the ability to alter cell proliferation and gene expression in cells of importance to the periodontium. This communication reports on the in vivo concentrations of propionic and butyric acid in the gingival crevices of periodontal subjects with severe and mild disease. The results indicated that severely diseased subjects exhibited a > 10-fold increase in the mM concentration of these acids when compared with mildly diseased subjects (mean propionic acid-severe = 9.5 +/- 1.8 mM, and mild = 0.8 +/- 0.3 mM; mean butyric acid-severe = 2.6 +/- 0.4 mM, and mild = 0.2 +/- 0.04 mM). These differences (mean +/- SE) were significant (p < 0.0001). The propionic and butyric acid concentrations were below detection limits in healthy sites of mildly diseased subjects. The propionic and butyric acid concentrations also associated significantly with clinical measures of disease severity (e.g., pocket depth, attachment level) and inflammation (e.g., subgingival temperature, % of sites bleeding when probed), and with the total microbial load (all p < 0.05). Taken together, these data suggest that short-chain carboxylic acids play a mediating role in periodontal disease pathogenesis.

Aggregatibacter actinomycetemcomitans↗

PubMed2026

Scale reliant mixed effects models enhance microbiome data analysis.

Linear models, including those used for differential abundance analyses, are frequently used in microbiome research to assess how experimental conditions (e.g., disease state or age) affect microbial abundance. Linear mixed-effects models (MEMs) extend linear models to accommodate complex designs, such as longitudinal sampling or hierarchical study structures. However, when applied to microbiome data, existing MEM approaches suffer from high false positive and false negative rates because sequence counts are compositional - they reflect relative rather than absolute abundances. Current methods attempt to overcome this limitation through normalization, but these approaches rely on strong, often unrealistic assumptions about the unmeasured biological scale (e.g., total microbial load). Here we introduce scale-reliant mixed-effects models (SR-MEM), which extend our earlier scale-reliant inference framework by explicitly modeling uncertainty in the unmeasured scale via user-defined probability distributions. By treating scale as a latent variable rather than fixing it through normalization, SR-MEM enables robust inference for complex experimental designs. SR-MEM can incorporate external scale measurements (e.g., flow cytometry, qPCR) or leverage scale information from independent studies to further improve inference. Across simulations and multiple real-world case studies, SR-MEM consistently controls the false discovery rate while maintaining comparable or higher power than standard approaches relying on normalization or bias correction. In reanalyses of published datasets, SR-MEM yields results that are more reproducible across studies and more consistent with known biological and pharmacological effects. SR-MEM provides a principled and practical framework for mixed-effects modeling of microbiome sequence count data in the presence of unmeasured biological scale. By avoiding normalization-based assumptions and instead propagating scale uncertainty through inference, SR-MEM improves error control and reproducibility in longitudinal and hierarchical studies. An accessible implementation is provided in the ALDEx3 R package.

Microbiota↗

PubMed2005

Influence of thermal processing conditions on flavor stability in fluid milk: benzaldehyde.

Flavor loss in dairy products has been associated with enzymatic degradation by xanthine oxidase. This study was conducted to investigate the influence of milk thermal processing conditions (or xanthine oxidase inactivation) on benzaldehyde stability. Benzaldehyde was added to whole milk which had been thermally processed at 4 levels: (1) none or raw, (2) high temperature, short time (HTST) pasteurization, (3) HTST pasteurization, additionally heated to 100 degrees C (PAH), and (4) UHT sterilized. Additionally, PAH and UHT milk samples containing benzaldehyde (with and without ferrous sulfate) were spiked with xanthine oxidase. Azide was added as an antimicrobial agent (one additional pasteurized sample without) and the microbial load (total plate count) was determined on d 0, 2, and 6. The concentration of benzaldehyde and benzoic acid in all milk samples were determined at d 0, 1, 2, 4, and 6 (stored at 5 degrees C) by gas chromatography/mass spectrometry in selective ion monitory mode. Over the 6-d storage period, more than 80% of the benzaldehyde content was converted (oxidized) to benzoic acid in raw and pasteurized milk, whereas no change in the benzaldehyde concentration was found in PAH or UHT milk samples. Furthermore, the addition of xanthine oxidase or xanthine oxidase plus ferrous sulfate to PAH or UHT milk samples did not result in benzaldehyde degradation over the storage period.

Animals↗

PubMed2002

Quantitative microbiological study of human carious dentine by culture and real-time PCR: association of anaerobes with histopathological changes in chronic pulpitis.

The bacteria found in carious dentine were correlated with the tissue response of the dental pulps of 65 teeth extracted from patients with advanced caries and pulpitis. Standardized homogenates of carious dentine were plated onto selective and nonselective media under anaerobic and microaerophilic conditions. In addition, real-time PCR was used to quantify the recovery of anaerobic bacteria. Primers and fluorogenic probes were designed to detect the total anaerobic microbial load, the genera Prevotella and Fusobacterium, and the species Prevotella melaninogenica, Porphyromonas endodontalis, Porphyromonas gingivalis, and Micromonas (formerly Peptostreptococcus) micros. The pulpal pathology was categorized according to the cellular response and degenerative changes. Analysis of cultured bacteria showed a predominance of gram-positive microorganisms, particularly lactobacilli. Gram-negative bacteria were also present in significant numbers with Prevotella spp., the most numerous anaerobic group cultured. Real-time PCR analysis indicated a greater microbial load than that determined by colony counting. The total number of anaerobes detected was 41-fold greater by real-time PCR than by colony counting, while the numbers of Prevotella and Fusobacterium spp. detected were 82- and 2.4-fold greater by real-time PCR than by colony counting, respectively. Real-time PCR also identified M. micros, P. endodontalis, and P. gingivalis in 71, 60, and 52% of carious samples, respectively. Correlation matrices of the real-time PCR data revealed significant positive associations between M. micros and P. endodontalis detection and inflammatory degeneration of pulpal tissues. These anaerobes have been strongly implicated in endodontic infections that occur as sequelae to carious pulpitis. Accordingly, the data suggest that the presence of high levels of these bacteria in carious lesions may be indicative of irreversible pulpal pathology.

Bacteria, Anaerobic↗

PubMed2006

Intra-storm variability in microbial partitioning and microbial loading rates.

Association with particles in the water column can have a significant impact on microbial fate and transport. This study analyzed multiple stormwater samples taken throughout the duration of three separate storms (at two different sites) to evaluate the fraction of microbes partitioning to denser "settleable" particles and to examine how partitioning behavior varied over the course of a storm. Intra-storm sampling also allowed for estimates of microbial loading rates (both total and particle-associated) and cumulative storm-induced microbial load. Five different indicator organisms were examined, with the fraction of microbes associated with settleable particles assessed via a calibrated centrifugation method. Partitioning behavior varied across microorganism type, with an average of 40% of fecal coliforms, Escherichia coli, and enterococci associating with settleable particles, compared to approximately 65% of Clostridium perfringens spores and only 13% of total coliphage. Partitioning remained fairly constant for each type of organism throughout storm events. Nonetheless, higher concentrations of both settleable particles and microbes entering the water column soon after the onset of a storm led to higher loading rates of settleable microbes in the storm's earliest stages, a trend that could have important implications for the design of stormwater management structures (e.g., detention basins). Estimates of cumulative storm-induced microbial loading suggested that one day's worth of storm loading can be the equivalent of months, or even years, of dry-weather loading.

Clostridium perfringens↗

PubMed2006

Microbiological profiles, pH, and titratable acidity of chorizo and salchichón (two Spanish dry fermented sausages) manufactured with ostrich, deer, or pork meat.

Microbial counts, pH, and titratable acidity were determined in 102 Spanish dry fermented sausages (chorizo and salchichón) made with ostrich, deer, or pork meat. Average microbial counts (log CFU per gram) varied from 5.46 +/- 0.24 to 8.25 +/- 0.80 (total viable counts), from 4.79 +/- 0.36 to 7.99 +/- 0.20 (psychrotrophs), from 0.00 +/- 0.00 to 0.99 +/- 1.10 (undetectable values were assumed to be zero) (Enterobacteriaceae), from 0.00 +/- 0.00 to 4.27 +/- 1.47 (enterococci), from 5.15 +/- 1.15 to 8.46 +/- 0.49 (lactic acid bacteria), from 3.08 +/- 0.44 to 6.59 +/- 1.76 (Micrococcaceae), from 2.27 +/- 1.53 to 5.11 +/- 1.81 (molds and yeasts), from 0.00 +/- 0.00 to 2.25 +/- 0.81 (pseudomonads), and from 0.00 +/- 0.00 to 2.78 +/- 0.46 (Brochothrix thermosphacta). Average pH and titratable acidity varied from 5.07 +/- 0.25 to 5.63 +/- 0.51 (pH units) and from 0.30 +/- 0.01 to 0.86 +/- 0.19 (% lactic acid). Both type of sausage (P < 0.05) and species of meat (P < 0.001) influenced microbial counts. Salchich6n samples showed lower average values than chorizo samples for most microbial groups (significant for Enterobacteriaceae, lactic acid bacteria, and B. thermosphacta) and titratable acidity. Sausages made from pork showed the highest microbial loads for total viable counts, psychrotrophs, Enterobacteriaceae, enterococci, lactic acid bacteria, and yeasts and molds. Higher counts were observed only for pseudomonads in ostrich sausages. B. thermosphacta levels were similar for all species of meat. The highest average pH value was observed in sausages made from ostrich meat, and the lowest titratable acidity level was found in pork sausages.

Animals↗

PubMed2004

Prevalence of Clostridium species and behaviour of Clostridium botulinum in gnocchi, a REPFED of italian origin.

Sales and consumption of refrigerated processed foods of extended durability (REPFEDs) have increased many-fold in Europe over the last 10 years. The safety and quality of these convenient ready-to-eat foods relies on a combination of mild heat treatment and refrigerated storage, sometimes in combination with other hurdles such as mild preservative factors. The major hazard to the microbiological safety of these foods is Clostridium botulinum. This paper reports on the prevalence and behaviour of proteolytic C. botulinum and non-proteolytic C. botulinum in gnocchi, a potato-based REPFED of Italian origin. Attempts to isolate proteolytic C. botulinum and non-proteolytic C. botulinum from gnocchi and its ingredients were unsuccessful. Based on assessment of the adequacy of the methods used, it was estimated that for proteolytic C. botulinum there was < 25 spores/kg of gnocchi and < 70 spores/kg of ingredients. The total anaerobic microbial load of gnocchi and its ingredients was low, with an estimated 1 MPN/g in processed gnocchi. Most of the anaerobic flora was facultatively anaerobic. A few obligately anaerobic bacteria were isolated from gnocchi and its ingredients and belonged to different Clostridium species. The protection factor, number of decimal reductions in the probability of toxigenesis from a single spore, was determined for eight different gnocchi formulations by challenge test studies. For all gnocchi stored at 8 degrees C (as recommended by the manufacturer) or 12 degrees C (mild temperature abuse), growth and toxin production were not detected in 75 days. The protection factor was >4.2 for proteolytic C. botulinum, and >6.2 for non-proteolytic C. botulinum. When inoculated packs were stored at 20 degrees C (severe temperature abuse), toxin production in 75 days was prevented by the inclusion of 0.09% (w/w) sorbic acid (protection factors as above), however in the absence of sorbic acid the packs became toxic before the end of the intended shelf-life and the protection factors were lower. Providing sorbic acid (0.09% w/w) is included in the gnocchi, the safety margin would seem to be very large with respect to the foodborne botulism hazard.

Ascorbic Acid↗

PubMed1999

Application of laser scanning for the rapid and automated detection of bacteria in water samples.

It is widely accepted that the heterotrophic plate count method may not support the growth of all viable bacteria which may be present within a water sample and that alternative procedures using 'viability markers' may yield additional information. In this study, ChemChrome B (CB), which is converted to a fluorescent product by esterase activity, was used to stain viable bacteria (captured by membrane filtration) from potable water samples. The labelled bacteria from each sample were subsequently enumerated using a novel laser scanning instrument (ChemScan). Analysis of 107 potable water samples using this procedure demonstrated the presence of a significantly greater number of bacteria than were detected by culture (z-test, P < 0.05). The mean number of bacteria isolated by culture on R2A agar incubated at 22 degrees C for 7 d was only 25.2% of the total number of viable bacteria detected using the CB/ChemScan viability assay. Further analysis of 81 water samples using a 5-cyano-2,3,4-tolyl-tetrazolium chloride (CTC) viability assay also demonstrated the presence of many viable bacteria which were not capable of growth under the culture conditions employed in this study. However, the results indicate that ChemChrome B has the ability to stain a significantly greater number of heterotrophs than CTC (z-test, P < 0.05). In contrast, six potable waters were identified in which the CTC viability assay resulted in counts greater than those obtained using CB. The ChemScan instrument was successfully used for rapid and accurate enumeration of labelled micro-organisms, allowing information on the total viable microbial load of a water sample to be determined within 1 h. Furthermore, the ChemScan system has the potential for use in detecting specific organisms labelled with fluorescently-labelled antibodies or nucleic acid probes.

Bacteria↗

PubMed2003

Development of a miniaturized four-culture method for the rapid enumeration of four bacterial groups in ground beef.

AIMS: A simplified and rapid method was developed to identify and enumerate total mesophilic microbial load, gram-negative bacteria, coliforms, and Escherichia coli in ground beef, using a single module. METHODS AND RESULTS: A 96-well microtiter plate was divided into four sections of two lanes (24 wells), with each section dedicated to each of the four critical bacterial groups. Double strength of four different selective broths (100 microl) was added to each well and an aliquot of sample (100 microl) from the first well was transferred to the next to achieve a twofold serial dilution in each series (24 wells). Initial bacterial load was calculated using the final consecutive positive reaction exhibiting color change or fluorescence. To validate the method, ground beef (n = 32), inoculated with a three-strain mixture of E. coli, together with 30 samples of commercial ground beef, were assayed by the four-culture method and conventional plating. For all media tested, the coefficients of determinations (r2) between the results derived from the four-culture method and those of conventional plating method ranged from 0.83 to 0.92. CONCLUSIONS: The high degree of association between the two methods indicates that the four-culture method could be easily applied to the enumeration of four critical bacterial groups in ground beef. SIGNIFICANCE AND IMPACT OF THE STUDY: This method will facilitate sanitation monitoring at meat processing plants by shortening time required for results, reducing consumable material costs, simplifying procedures, reducing the space required, and cutting the cost of start up equipment.

Animals↗

PubMed2003

The combined use of whole Cuphea seeds containing medium chain fatty acids and an exogenous lipase in piglet nutrition.

In search for an alternative for nutritional antimicrobials in piglet feeding, the effects of adding whole Cuphea seeds, as a natural source of medium chain fatty acids (MCFA), with known antimicrobial effects, and an exogenous lipase to a weaner diet were studied. The foregut flora, the gut morphology, some digestive parameters and the zootechnical performance of weaned piglets were investigated. Thirty newly weaned piglets, initial weight 7.0 +/- 0.4 kg, were divided according to litter, sex and weight in two groups (control diet; Cuphea + lipase diet). The Cuphea seeds (lanceolata and ignea) (50 g kg(-1)) were substituted for soybean oil (15 g kg(-1)), Alphacell (25 g kg(-1)) and soy protein isolate (10 g kg(-1)) in the control diet. Also 500 mg kg(-1) microbial lipase was added to the Cuphea diet. The piglets were weighted individually on days 0, 3. 7, 14 and 16. Feed intake was recorded per pen during days 0 to 3, 3 to 7, 7 to 14 and 14 to 16. On day 7 five piglets of each experimental group were euthanized for counting the gastric and small intestinal gut flora and for gut morphology at two sites of the small intestine (proximal, distal). The results indicate a trend towards improved performances parameters by feeding Cuphea + lipase. The enzymic released MCFA (1.7 g kg(-1) fresh gastric contents) tended to decrease the number of Coliforms in the proximal small intestine, but increased the number in the stomach and distal small intestine. With Culphea, the number of Streptococci was significantly lower in small intestine, but not in the stomach, while the number of Lactobacilli was significantly lower in the distal small intestine and tended to be lower in the stomach and proximal small intestine. No differences between the diets were noted for the total anaerobic microbial load in the stomach or in the gut. Feeding Cuphea + lipase resulted in a significantly greater villus height (distal small intestine) and a lesser crypt depth (proximal and distal small intestine) and greater villus/crypt ratio depth (proximal and distal small intestine). The intra-epithelial lymphocyte (IEL) counts per 100 enterocytes were significantly decreased in the proximal small intestine and tended to decrease in the distal small intestine by feeding the Cuphea + lipase diet. Both phenomena are indicative for a more healthy and better functional state of the mucosa. Present results are in line with foregoing research, showing that manipulation of the gut ecosystem by the enzymic in situ released MCFA in the stomach and foregut can result in improved performances of the piglets, which makes the concept a potential alternative for in-feed nutritional antibiotics.

Animal Feed↗

PubMed2002

Rapid and simple estimation of microbiological quality of raw milk using chromogenic Limulus amoebocyte lysate endpoint assay.

A rapid chromogenic Limulus amoebocyte lysate (LAL) endpoint assay for the enumeration of total mesophilic microbial loads and coliforms was investigated as a means to assess the microbiological quality of raw milk. For experiment 1, raw milk samples (n = 25) were stored in a refrigerator (2 +/- 2 degrees C) and then analyzed at regular intervals (1, 5, 10, and 15 days). For experiment 2, fresh raw milk samples (n = 50) were tested to determine the utility of the LAL assay for fresh raw milk. The sample was diluted threefold in a 96-well microtiter plate with pyrogen-free water and assayed with a chromogenic LAL kit to find a final reaction point. The LAL results were compared with standard plate counts (SPC) and coliform counts determined by conventional plating methods. The results of the LAL assay were strongly correlated to conventional SPC (r2 = 0.93; n = 100) and were highly correlated to coliforms (r2 = 0.74; n = 100). A highly significant linear relationship (r2 = 0.82; n = 50) was also observed between the predicted SPC based on the LAL value and the actual SPC. The results of LAL testing were classified into one of seven contamination groups. The data set for SPC was effectively differentiated using the LAL technique (P < 0.01). The chromogenic LAL assay was found to be a rapid (within 16 min) and simple (not requiring specific instruments) method for monitoring microbial levels in raw milk. This method may be successfully implemented to rapidly determine highly microbial contaminated raw milk (> 3.0 log10 CFU/ml of SPC).

Animals↗

PubMed2001

Bioluminescence ATP assay for estimating total plate counts of surface microflora of whole cantaloupe and determining efficacy of washing treatments.

The surface microflora of cantaloupes were estimated using a bioluminescence ATP assay, and results were compared to plate count data. Cantaloupes were treated as follows: (i) water washed, or (ii) washed in solutions of sodium hypochlorite (1,000 mg/liter) or hydrogen peroxide (5%) for 5 min. Bioluminescence ATP assay results showed differences in ATP level/cm2 of cantaloupes dipped in chlorine or hydrogen peroxide solution; ATP levels in these washed samples were lower than in controls due to antimicrobial action of the treatments on the cantaloupe surface. Linear correlations were found between the bioluminescence ATP assay and aerobic plate counts of unwashed cantaloupe (r2 = 0.995) and those washed with water (r2 = 0.990) determined before storage. Lower correlations between the bioluminescence ATP assay and the aerobic plate counts were observed on cantaloupes stored for 120 h at 20 degrees C (r2 = 0.751) than at 4 degrees C (r2 = 0.980) without washing treatment. Lower correlation at 20 degrees C may be the result of clusters or growth that occurred in chains. ATP levels of washed cantaloupes correlated well with bacterial plate counts (r2 = 0.999). A reliable minimum detectable threshold using the bioluminescence ATP assay was established at 3 log10 fg/cm2 corresponding to 4 log10 CFU/cm2. Bioluminescence ATP assay is not recommended for washed samples where the microbial load is near or below the threshold. Therefore, the bioluminescence ATP assay will be recommended for quick estimation of total microbial load on cantaloupe surfaces where the population is expected to exceed this threshold. The assay can save the industry time by eliminating the required incubation required by the conventional methods.

Adenosine Triphosphate↗

PubMed1986

Studies on microorganisms secured from different organs of slaughtered sheep with special reference to the microbial load in certain muscles.

A total of 312 samples collected from different organs and muscles of dead, disabled, diseased, dying, and normal carcasses of sheep were examined bacteriologically to determine the different species of microorganisms as to their public health significance. In addition, the aerobic plate count (APC) and most probable number (MPN) coliform/g were determined of Musculus biceps brachii, Musculus quadriceps femoris, and Musculus longissimus dorsi. The mean bacterial load was higher in summer than in winter in dead and in normal sheep. Moreover, the APC was higher in winter 3 hours after slaughtering than after 24 h cooling. The bacterial load decreased in that order in the muscles of dead, disabled, diseased, and dying sheep carcasses. The lowest bacterial load was recorded in the Musculus longissimus dorsi. The most predominant isolates recovered from different organs and muscles were Escherichia coli (60), staphylococci (33), Proteus vulgaris (12), Enterobacter aerogenes (11), Corynebacterium ovis (9), Alcaligenes faecalis (7), Actinomyces israelii (5), Citrobacter freundii (4), pneumococci (3), and enterococci (2). The importance is discussed of the isolated strains as zoonotic agents and for assessing the hygienic meat quality.

Animals↗

PubMed2003

Differences in hyporheic-zone microbial community structure along a heavy-metal contamination gradient.

The hyporheic zone of a river is nonphotic, has steep chemical and redox gradients, and has a heterotrophic food web based on the consumption of organic carbon entrained from downwelling surface water or from upwelling groundwater. The microbial communities in the hyporheic zone are an important component of these heterotrophic food webs and perform essential functions in lotic ecosystems. Using a suite of methods (denaturing gradient gel electrophoresis, 16S rRNA phylogeny, phospholipid fatty acid analysis, direct microscopic enumeration, and quantitative PCR), we compared the microbial communities inhabiting the hyporheic zone of six different river sites that encompass a wide range of sediment metal loads resulting from large base-metal mining activity in the region. There was no correlation between sediment metal content and the total hyporheic microbial biomass present within each site. However, microbial community structure showed a significant linear relationship with the sediment metal loads. The abundances of four phylogenetic groups (groups I, II, III, and IV) most closely related to alpha-, beta-, and gamma-proteobacteria and the cyanobacteria, respectively, were determined. The sediment metal content gradient was positively correlated with group III abundance and negatively correlated with group II abundance. No correlation was apparent with regard to group I or IV abundance. This is the first documentation of a relationship between fluvially deposited heavy-metal contamination and hyporheic microbial community structure. The information presented here may be useful in predicting long-term effects of heavy-metal contamination in streams and provides a basis for further studies of metal effects on hyporheic microbial communities.

Alphaproteobacteria↗

PubMed2001

Alfalfa seed germination and yield ratio and alfalfa sprout microbial keeping quality following irradiation of seeds and sprouts.

Foods can be treated with gamma radiation, a nonthermal food process, to inactivate foodborne pathogens and fungi, to kill insects on or in fruits and vegetables, and to increase shelf life. Gamma irradiation is especially well suited for these treatments because of its ability to penetrate commercial pallets of foods. Irradiated fruits, vegetables, poultry, and hamburger have been received favorably by the public and are now available in supermarkets. The use of irradiation on fresh alfalfa sprouts was studied to determine its effect on keeping quality as related to aerobic microbial load. After an irradiation dose of 2 kGy, the total aerobic count decreased from 10(5-8) to 10(3-5) CFU/g, and the total coliform counts decreased from 10(5-8) to 10(3-0) CFU/g. The results showed that the sprouts maintained their structure after irradiation, and the keeping quality was extended to 21 days, which is an increase of 10 days from the usual shelf life. The effect of various doses of irradiation on alfalfa seeds as measured by percent germination and yield ratio (wt/wt) of sprouts was determined. There was little effect on the percent germination, but as the dose increased, the yield ratio of alfalfa sprouts decreased. As the length of growing time increased, so did the yield ratio of the lower dose irradiated seeds (1 to 2 kGy). The irradiation process can be used to increase the shelf life of alfalfa sprouts, and irradiating alfalfa seeds at doses up to 2 kGy does not unacceptably decrease the yield ratio for production of alfalfa sprouts.

Bacteria↗

PubMed2006

A microbiologic study of enteral feeding hang time in a burn hospital: can feeding costs be reduced without compromising patient safety?

BACKGROUND: Procedural changes for hospitalized patients must always balance safety with fiscal constraints. Microbiologic contamination of enteral feeding solutions has been previously associated with nosocomial infections. Formula manipulation and hang time contribute to microbial load, and there is considerable variation in hang time recommendations in the medical literature. With cost containment in mind, the purpose of this performance improvement study was to determine if an increase in hang time of a modular tube feeding product would increase microbial load or affect the nosocomial infection rate in pediatric burn patients. METHODS: This biphasic trial initially evaluated the microbial load of the feeding after delivery of two 4-hour aliquots into a container using the same delivery set (total hang time of 8 hours; number of tests = 20). Second, once this feeding procedure was deemed microbiologically safe, tube feedings were administered to patients, and both microbial load and nosocomial infection rate were monitored for 1 year. RESULTS: Contamination levels at the end of the 8-hour period using the same feeding set with 2 consecutive 4-hour feeding aliquots (number of tests = 38) were lower than standard recommendations. The hospital's nosocomial infection rate was not altered by this procedural change, and feeding-set expenses were reduced. CONCLUSIONS: The hang time of our enteral feeding administration set can be increased safely from 4 hours to 8 hours, with the tube feeding preparation added as two 4-hour aliquots without a significant change in microbial load or nosocomial infection rate, thus promoting simultaneous fiscal responsibility and patient safety.

Burn Units↗