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PubMed2006

Resident lactic acid bacteria in raw milk Canestrato Pugliese cheese.

AIMS: Investigation of the autochthonous lactic acid bacteria (LAB) population of the raw milk protected designation of origin Canestrato Pugliese cheese using phenotypic and genotypic methodologies. METHODS AND RESULTS: Thirty phenotypic assays and three molecular techniques (restriction fragment length polymorphism, partial sequencing of the 16S rRNA gene and recA multiplex PCR assay) were applied to the identification of 304 isolates from raw milk Canestrato Pugliese cheese. As a result, 168 of 207 isolates identified were ascribed to genus Enterococcus, 25 to Lactobacillus, 13 to Lactococcus and one to Leuconostoc. More in details among the lactobacilli, the species Lactobacillus brevis and Lactobacillus plantarum were predominant, including 13 and 10 isolates respectively, whereas among the lactococci, Lactococcus lactis subsp.cremoris [corrected] was the species more frequently detected (seven isolates). CONCLUSIONS: Except for the enterococci, phenotypic tests were not reliable enough for the identification of the isolates, if not combined to the genotype-based molecular techniques. The polyphasic approach utilized allowed 10 different LAB species to be detected; thus suggesting the appreciable LAB diversity of the autochthonous microbial population of the Canestrato Pugliese cheese. SIGNIFICANCE AND IMPACT OF THE STUDY: A comprehensive study of the resident raw milk Canestrato Pugliese cheese microbial population has been undertaken.

Animals↗

PubMed1993

Amounts of viable anaerobes, methanogens, and bacterial fermentation products in feces of rats fed high-fiber or fiber-free diets.

We investigated the impact of dietary fiber on the fecal output of microorganisms and microbial fermentation products of rats. Two groups of five male Wistar rats were fed high-fiber (HF) and fiber-free (FF) diets in the following order: (group 1) lab chow-->HF-->FF-->HF and (group 2) lab chow-->FF-->HF-->FF. Daily fecal output of total viable anaerobes was 71 times higher with the HF diet. Daily output of methanogens was 1.4 times higher for the HF diet than for the FF diet. Daily excretion of total fermentation acid products (acetate, propionate, butyrate, lactate, succinate, and formate) was 2.4 and 0.1 mmol for HF and FF diets, respectively. The ratios of acetate/propionate/butyrate were 69:21:10 for the HF diet and 92:7:1 for the FF diet. The results show that an HF diet significantly increases microbial growth in the colon and influences the proportions of organic acid products. The HF diet did not increase the ratio of methanogens to total anaerobes. We suggest that the contribution of host-derived substrates to colonic microbial growth and fermentation is insignificant.

Animals↗

PubMed2006

Antimicrobial activity of potassium hydroxide and lauric acid against microorganisms associated with poultry processing.

The antimicrobial activity of solutions of potassium hydroxide (KOH) and mixtures of KOH and lauric acid against microorganisms associated with poultry processing was determined. In vitro tests were performed by enumerating viable microorganisms recovered from bacterial cultures suspended in peptone water (control) and in solutions of 0.1% KOH or mixtures of 0.1% KOH and 0.25 or 0.50% lauric acid. Additional studies were conducted to identify changes in the native microbial flora of poultry skin washed in distilled water, KOH, or KOH-lauric acid. Although results of in vitro studies indicated that significantly fewer bacteria (P < or = 0.05) were recovered from cultures suspended in KOH than from cultures suspended in peptone water, there were also significantly fewer bacteria recovered from cultures suspended in KOH-lauric acid than from cultures suspended in KOH. Results of experiments with broiler skin indicated that although rinsates of skin washed in 1.0% KOH solutions contained significantly fewer total aerobic bacteria and enterococci than did skin washed in water, significantly fewer of these microorganisms were generally recovered from rinsates of skin washed in mixtures of 1.0% KOH and 0.5, 1.0, 1.5, or 2.0% lauric acid than from skin washed in KOH alone. Washing of broiler skin in solutions of 0.25 to 1.00% KOH or mixtures containing these concentrations of KOH and two parts lauric acid (wt/vol) also significantly reduced the populations of bacteria and yeasts in the native flora of broiler skin. Enterococci, lactic acid bacteria, and staphylococci in the native flora of the skin had the highest level of resistance to the bactericidal activity of KOH-lauric acid. These findings indicate that the antimicrobial activity of KOH-lauric acid is significantly greater than that of KOH alone in vitro and on poultry skin. Thus, KOH-lauric acid may be useful for reducing the level of microbial contamination associated with poultry processing.

Animals↗

PubMedDate not supplied

Waterline biofilm and the dental treatment facility: a review.

Biofilms are well-organized communities of cooperating microorganisms that can include bacteria, protozoa, diatoms, and fungi. Surveys of dental unit waterlines (DUWLs) indicate that biofilm formation is a universal problem and that environmental and human-derived opportunistic pathogens can be cultured consistently from biofilms retrieved from DUWLs and other dental devices. Although the health risks presented by waterline bacterial colonization have yet to be adequately addressed, professional and ethical considerations indicate that steps should be taken to improve the quality of DUWLs. To address these concerns, the Council on Scientific Affairs of the ADA recently published a list of products cleared by the FDA to control dental waterline contamination. The goal of this article is to increase the awareness of potential health risks posed by biofilm formation and provide information on techniques and devices designed to control the microbial contamination of DUWLs.

Bacteria↗

PubMedDate not supplied

Low-cost screening for microbial contaminants in aerosols generated in a dental office.

It has been reported that aerosols and droplets generated by high-speed dental drills and cavitrons are contaminated with blood and bacteria and represent a potential route for transmitting disease. Bacterial cells possess a negative electrical charge, while the cathode ray tubes (CRT) that are used in computer monitors generate positively charged static electric fields. Consequently, bacteria dispersed within these aerosols could be attracted to the screens on CRT monitors. In this study, pathogenic strains of Staphylococcus aureus were found on CRT screens in different locations within the Louisiana State University School of Dentistry facility. The results suggest that surveying CRT screens is a simple method for evaluating the airborne microbial contaminants present within a dental office.

Aerosols↗

PubMed2005

Cross-contamination of the PSP sensor in a preclinical setting.

PURPOSE: This study tested an infection control protocol for photostimulable phosphor (PSP) sensors while simulating multiple uses. METHODS: Dental hygiene students (n=36) were randomly assigned to a control group (dry wipe) or test group (disinfectant wipe). A sterile, barriered sensor was placed in a peer patient's mouth to simulate an exposure. After simulation, the barriered sensors were disinfected, placed into a new barrier, and inserted into the same peer patient's mouth. Following the fourth placement and treatment, sensors were vortexed in specimen cups containing trypticase soy broth (TSB) and incubated at 37 degrees C to detect contamination by oral bacteria. RESULTS: Bacterial growth in TSB was monitored as a change in optical density and by quantitation of oral streptococci on Mitis-salivarius agar. The barrier-protected sensors were minimally contaminated (<10(5) colony forming units/ml at baseline) regardless of treatment. After culture amplification, the control TSB had more samples that remained negative through 48 hours (5/18 vs. 0/18 for test group, p<0.05). CONCLUSION: Barrier envelopes used with the PSP sensors appeared to be an effective way of reducing microbial contamination.

Biphenyl Compounds↗

PubMed2006

Salmonella prevalence and total microbial and spore populations in spices imported to Japan.

A total of 259 samples of 40 types of spices were tested for Salmonella prevalence and total microbial and spore populations. Salmonella enterica serotypes Weltevreden and Senftenberg were isolated from a black- and red-pepper sample, respectively. Because Salmonella was not detected by the most-probable-number method, it indicated that at least one cell of the microorganism was present in 25 g of sample. The mean aerobic bacterial count was greater than 5.39 log CFU/g in turmeric, garam masala, curry powder, and paprika. The mean bacterial spore counts were greater than 4.33 log CFU/g in turmeric and curry powder. The mean aerobic bacterial count in the two Salmonella-isolated samples was 6.93 log CFU/g. These results indicate that spices can be a source of contamination in the products where they are used as ingredients, and methods to reduce the microbial load in spices should be used.

Bacteria, Aerobic↗

PubMed2003

Automated enumeration of groups of marine picoplankton after fluorescence in situ hybridization.

We describe here an automated system for the counting of multiple samples of double-stained microbial cells on sections of membrane filters. The application integrates an epifluorescence microscope equipped with motorized z-axis drive, shutters, and filter wheels with a scanning stage, a digital camera, and image analysis software. The relative abundances of specific microbial taxa are quantified in samples of marine picoplankton, as detected by fluorescence in situ hybridization (FISH) and catalyzed reporter deposition. Pairs of microscopic images are automatically acquired from numerous positions at two wavelengths, and microbial cells with both general DNA and FISH staining are counted after object edge detection and signal-to-background ratio thresholding. Microscopic fields that are inappropriate for cell counting are automatically excluded prior to measurements. Two nested walk paths guide the device across a series of triangular preparations until a user-defined number of total cells has been analyzed per sample. A backup autofocusing routine at incident light allows automated refocusing between individual samples and can reestablish the focal plane after fatal focusing errors at epifluorescence illumination. The system was calibrated to produce relative abundances of FISH-stained cells in North Sea samples that were comparable to results obtained by manual evaluation. Up to 28 preparations could be analyzed within 4 h without operator interference. The device was subsequently applied for the counting of different microbial populations in incubation series of North Sea waters. Automated digital microscopy greatly facilitates the processing of numerous FISH-stained samples and might thus open new perspectives for bacterioplankton population ecology.

Automation↗

PubMed2001

Bioremediation (natural attenuation and biostimulation) of diesel-oil-contaminated soil in an alpine glacier skiing area.

We investigated the feasibility of bioremediation as a treatment option for a chronically diesel-oil-polluted soil in an alpine glacier area at an altitude of 2,875 m above sea level. To examine the efficiencies of natural attenuation and biostimulation, we used field-incubated lysimeters (mesocosms) with unfertilized and fertilized (N-P-K) soil. For three summer seasons (July 1997 to September 1999), we monitored changes in hydrocarbon concentrations in soil and soil leachate and the accompanying changes in soil microbial counts and activity. A significant reduction in the diesel oil level could be achieved. At the end of the third summer season (after 780 days), the initial level of contamination (2,612 +/- 70 microg of hydrocarbons g [dry weight] of soil(-1)) was reduced by (50 +/- 4)% and (70 +/- 2)% in the unfertilized and fertilized soil, respectively. Nonetheless, the residual levels of contamination (1,296 +/- 110 and 774 +/- 52 microg of hydrocarbons g [dry weight] of soil(-1) in the unfertilized and fertilized soil, respectively) were still high. Most of the hydrocarbon loss occurred during the first summer season ([42 +/- 6]% loss) in the fertilized soil and during the second summer season ([41 +/- 4]% loss) in the unfertilized soil. In the fertilized soil, all biological parameters (microbial numbers, soil respiration, catalase and lipase activities) were significantly enhanced and correlated significantly with each other, as well as with the residual hydrocarbon concentration, pointing to the importance of biodegradation. The effect of biostimulation of the indigenous soil microorganisms declined with time. The microbial activities in the unfertilized soil fluctuated around background levels during the whole study.

Austria↗

PubMed1996

Treatment of periodontal disease based on microbiological diagnosis. A 5-year follow-up on individual patterns.

Sixteen patients with advanced periodontitis (more than 3 sites with a probing depth > or = 6 mm) were treated with the aim of eliminating Actinobacillus actinomyce-temcomitans and Porphyromonas gingivalis and reducing Prevotella intermedia below 5% of the total viable count. The patients were followed clinically and microbiologically for over 5 years and showed a highly individual pattern with respect to presence of indicator bacteria, type of treatment needed to accomplish treatment goals, clinical response, and bacterial and disease recurrencies. The results of this study suggest that presence of the indicator bacteria in microbial samples taken after treatment may identify patients at risk for recurrent periodontitis.

Adult↗

PubMed1993

The use of a concentrated oral rinse culture technique to sample oral candida and lactobacilli in children, and the relationship between candida and lactobacilli levels and dental caries experience: a pilot study.

The purpose of this study was to test the suitability of a concentrated rinse culture technique, previously applied to adults, as a method for sampling the oral cavity of children on a community basis. The technique was used to assess the levels of oral candida and lactobacilli in the mouths of a group of 32 14- to 15-year-old children and to relate this to their past caries experience. Caries experience was assessed by means of a DMFS count. Each subject rinsed with 10 ml of buffered saline for 1 minute for microbial sampling. The oral rinse was concentrated by centrifugation and cultured on to selective media for candida and lactobacilli. The rinse technique proved simple and effective as a means of sampling the oral flora in children. The level of candida was more easily assessed and appeared to be a more useful indicator of microbial risk factors in caries than the lactobacilli count.

Adolescent↗

PubMed2003

A ten-year cross-sectional and follow-up study of salivary flow rates and mutans streptococci and lactobacillus counts in elderly Swedish individuals.

PURPOSE: The whole salivary flow rates and microbial conditions were examined in a 10-year follow-up and cross-sectional study in a random sample of elderly inhabitants of Gothenburg. MATERIAL AND METHODS: Of the 208 individuals examined at baseline, forty-nine per cent participated in the follow-up, 56, 37 and nine persons, respectively, in the age groups of 65, 75 and 85 years. In addition, a new random sample of 98 individuals aged 55 year was examined. RESULTS: The mean secretion rate decreased significantly with increasing age in terms of unstimulated and stimulated whole saliva. Of the 200 participants, 50% were taking medication, which could have hyposalivatory side-effects. Persons with a daily intake of > or =4 drugs had significantly lower unstimulated and stimulated secretion rates. Forty-five persons reported subjective dryness in the mouth. The mean saliva secretion rates among these persons were significantly lower and the number of drugs consumed significantly higher than in people with no such complaints. The overall salivary counts of lactobacilli and mutants streptococci increased with age. Higher counts of these bacteria were found in persons wearing removable dentures than in persons without dentures. CONCLUSION: The salivary and microbial conditions ought to be continuously monitored in old people, in order to identify those who need oral health promotive measures.

Age Factors↗

PubMed1997

Changes in water microbial quality during bank filtration of lake water.

We studied, during a 2-year period, how the microbial stability of water changed when humus-rich lake water was filtered through the ground at a bank filtration water plant. The changes in microbial quality were followed as microbial numbers and growth activity. The filtration decreased microbial counts and growth ([3H]thymidine technique) in water up to 90%. The reduction in bacterial counts and growth depended on the filtration distance. The reduction was greatest between the lake and the first sampling point. Microbial numbers and growth declined steadily after infiltration with increased filtration distance. Viable counts of heterotrophic bacteria decreased faster than total bacterial counts along filtration. The microbial numbers and bacterial production in water followed seasonal changes in water temperature. Simultaneously with the microbial numbers, the concentrations of total organic carbon and assimilable organic carbon decreased during bank filtration. These results showed that microbial stability of humus-rich water was increased by filtration to a level generally found in natural groundwaters.

Bacteria↗

PubMed2005

Quantification of total bacteria, enterobacteria and lactobacilli populations in pig digesta by real-time PCR.

Jejunum digesta samples were taken from weaning pigs in order to evaluate real-time PCR (qPCR) as a method for quantifying pig gut bacteria. Total bacteria, lactobacilli and enterobacteria were quantified by qPCR and the results were compared with those obtained with traditional methods: 4',6-diamidino-2-phenylindole (DAPI staining) for total bacteria, selective culture for lactobacilli and enterobacteria. Real-time PCR showed higher values in terms of 16S rRNA gene copies than DAPI counts or CFU. Despite the differences, the lactobacilli:enterobacteria ratio was similar between methods (2.5 +/- 0.58 for qPCR and 3.1 +/- 0.71 for selective culture, P = 0.39). Possible reasons for the higher PCR counts are discussed considering both an overestimation with PCR by quantification of dead bacteria or free DNA and also an underestimation with conventional methods. Inherent differences in the pre-treatment of the samples could partially explain the discrepancies observed. Regardless of the numerical differences between methods, values obtained by qPCR and traditional methods showed a significant correlation for lactobacilli and total bacteria. In the light of these results, real-time PCR seems a valid method to quantify microbial shifts in the gastrointestinal tract.

Animals↗

PubMed2001

Biodiversity of Geodermatophilaceae isolated from altered stones and monuments in the Mediterranean basin.

An investigation was made into the occurrence and biodiversity of Geodermatophilaceae on 78 samples of altered stone surfaces from 24 monuments and natural stones in the Mediterranean basin; it was found that the total microbial counts ranged between 0 and 10(7) cfu g(-1) dry weight. Members of the Geodermatophilaceae family were isolated from 22 of the 78 samples examined, with the incidence of Geodermatophilaceae colonies in the cultivable population ranging from 1% to 100%. The highest percentage was found in six samples of markedly deteriorated stone. Sixty-five strains randomly isolated from the plates were clustered in six different groups by amplified 16S rDNA restriction analysis (ARDRA) using five different restriction enzymes. Twenty-five strains, representing all the ARDRA haplotypes, were characterized further by partial sequencing (350-550 bp) of the 16S rDNA and by analysing 76 morphological, metabolic and physiological properties. The strains were associated with three well-separated clusters of the genera Geodermatophilus, Blastococcus and Modestobacter. On the basis of 16S rDNA sequence and ARDRA analysis, only two strains were found to be related to the two reference strains of Geodermatophilus. All the others could be grouped with Blastococcus aggregatus (19 strains) or the Antarctic species Modestobacter multiseptatus (44 strains), suggesting that it is these two groups, rather than Geodermatophilus, that tend to colonize the stone surfaces, and that Modestobacter-like strains are also found in temperate/Mediterranean climates. From the BOX-polymerase chain reaction (PCR) data, it can be seen that the Modestobacter-like strains, belonging to the most represented ARDRA haplotype (haplotype B, 34 strains), are very polymorphic and that, over a stone surface, there is a wide genetic diversity at the microsite level.

Actinomycetales↗

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↗

PubMed2002

The effect of different cooking procedures on microbiological and chemical quality characteristics of Tekirdağ meatballs.

In this research, the effects of different cooking processes (grilling, oven, and microwave cooking) on microbial flora and chemical composition of the raw and cooked meatballs as consumed in Tekirdağ were investigated. Microbial flora of the raw meatballs was as follows: total bacteria, 6.02 x 10(6) cfu/g; psychrophilic bacteria, 1.3 x 10(5) cfu/g; yeast and mould, 2.4 x 10(5) cfu/g; coliforms, 1.1 x 10(5) cfu/g; Escherichia coli, 1.0 x 10(2) cfu/g; total staphylococcae, 3.3 x 10(2) cfu/g; Staphylococcus aureus, 85 cfu/g. While Salmonella was found in only one sample, none of the samples contained Clostridium perfringens. The cooking processes clearly decreased the microbial flora (2-3 log cycles in grilling (71 degrees C) and oven-cooked (79 degrees C), 3-4 log cycles in microwave (97 degrees C) heating) of the meatballs. However, because of the crust formation and high moisture losses from the meatball surface in microwave heating, some sensorial defects were observed in the final product. Also, fat and moisture losses were higher in microwave cooking compared to the other cooking processes. In conclusion, it is advised to use slightly higher temperatures than used in the grilling or conventinal cooking procedures to increase microbial quality of the meatballs studied in this research.

Animals↗

PubMed2007

Characterization of a three bacteria mixed culture in a chemostat: evaluation and application of a quantitative terminal-restriction fragment length polymorphism (T-RFLP) analysis for absolute and species specific cell enumeration.

Growth dynamics of Pseudomonas aeruginosa, Burkholderia cepacia, and Staphylococcus aureus in a batch and chemostat, were investigated as a laboratory model system for persistent infections in cystic fibrosis. Most species-specific enumeration methods for mixed cultures are laborious or only qualitative, and therefore impede generation of quantitative data required for validation of mathematical models. Here, a quantitative T-RFLP method was evaluated and applied for specific and absolute cell number enumerations. The method was tested to be unbiased by quantitative sample composition and allowed reproducible enumerations of mixed cultures. For assay validation, samples of defined concentration containing one, two or three species were quantified. Logarithmically transformed absolute cell numbers of single-species dilutions were linear within a lower working range of 10(4)-10(6) cfu/mL (species-dependent) and an upper working range of 10(10) cfu/mL. Quantifications of single species (10(6)-10(10) cfu/mL) spiked with one or two other species agreed well with single species controls. Differences between slopes of first order linear regression of spiked and pure dilution series were insignificant. Coefficient of variation of defined mixed replicates was maximum 4.39%, of a three-species chemostat it was maximum 1.76%. T-RFLP monitoring of pure cultures in parallel shake flasks and of a three-species mixed chemostat gave very consistent results. Coexistence of at least two species after a time period equivalent to more than 33 volume exchanges was found. This result was not predicted from pure cultures clearly indicating the need for quantitative mixed culture experiments to better understand microbial growth dynamics and for mathematical model validation.

Biomass↗