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PubMed2006

A digital imaging procedure for seven-probe-labeling FISH (Rainbow-FISH) and its application to estuarine microbial communities.

For multi-probe-labeling fluorescence in situ hybridization (FISH), a digital imaging procedure was developed consisting of systematic background noise reduction and target signal equalization using a hue, saturation, value color partitioning technique. By the combined application of seven DNA probes, each labeled with three fluorochromes at maximum, seven kinds of cultured type strains were distinguished in a microscopic field simultaneously. Using this seven-probe-labeling FISH (Rainbow-FISH), several phylogenetic groups of microbes that occur frequently in aquatic environments, such as Alpha-, Beta- and Gammaproteobacteria, Cytophaga-Flavobacterium and Actinobacteria, were identified and quantified. The total counts of cells specified by Rainbow-FISH were in the range of 96-108% of those of general FISH, showing that the method is highly reliable for quantitative population analysis. Analyzing samples obtained at points along a river to a sea, we found a reverse population change in two groups: apparent decreases in Betaproteobacteria but gradual increases in Gammaproteobacteria. This method provides a platform toward the improvement of semiautomatic analysis of aquatic microbes under various metabolic conditions.

Actinobacteria↗
PubMed2003

Microbial and sensory quality of marinated and irradiated chicken.

Chicken legs were subjected to two pretreatments (packaged in air or marinated in natural plant extracts and then packaged in air) followed by irradiation (0, 3, or 5 kGy). The control and irradiated chicken legs were stored at 4 degrees C and underwent microbial analysis (mesophilic aerobic plate counts and Salmonella detection) and sensory evaluation at predetermined intervals. Microbial analysis indicated that irradiation had a significant effect (P < or = 0.05) on the mesophilic aerobic plate counts of the poultry. For each treatment, the bacterial growth decreased with an increase of irradiation dose. The marinade had an additive effect with irradiation in reducing bacterial growth and controlling proliferation during storage at 4 +/- 1 degree C. No Salmonella was observed until day 12 in marinated chicken irradiated at 3 kGy and for all experiments with chicken legs stored under air or marinated at 5 kGy. However, Salmonella was found in chicken legs irradiated at 3 kGy in air and in nonirradiated samples. The sensory evaluation indicated a significant (P < or = 0.05) difference in odor and flavor intensities between the irradiated chicken at 5 kGy and the control. No significant difference was found (P > 0.05) between the marinated chicken irradiated at 5 kGy and the control.

Animals↗
PubMed2005

Quantifying the robustness of a broth-based model for predicting Listeria monocytogenes growth in meat and poultry products.

Given the importance of Listeria monocytogenes as a risk factor in meat and poultry products, there is a need to evaluate the relative robustness of predictive growth models applied to meat products. The U.S. Department of Agriculture-Agricultural Research Service Pathogen Modeling Program is a tool widely used by the food industry to estimate pathogen growth, survival, and inactivation in food. However, the robustness of the Pathogen Modeling Program broth-based L. monocytogenes growth model in meat and poultry application has not, to our knowledge, been specifically evaluated. In the present study, this model was evaluated against independent data in terms of predicted microbial counts and covered a range of conditions inside and outside the original model domain. The robustness index was calculated as the ratio of the standard error of prediction (root mean square error of the model against an independent data set not used to create the model) to the standard error of calibration (root mean square error of the model against the data set used to create the model). Inside the calibration domain of the Pathogen Modeling Program, the best robustness index for application to meat products was 0.37; the worst was 3.96. Outside the domain, the best robustness index was 0.40, and the worst was 1.22. Product type influenced the robustness index values (P < 0.01). In general, the results indicated that broth-based predictive models should be validated against independent data in the domain of interest; otherwise, significant predictive errors can occur.

Animals↗
PubMed2004

Microbial, nutritional and physical quality of commercial and hospital prepared tube feedings in Saudi Arabia.

OBJECTIVE: Blenderized tube feedings (BTF) may present disadvantages over commercially prepared formulas (CPF). This study compares the microbial safety, nutritional content, and physical properties of BTF versus CPF. METHODS: A total of 18 samples of BTF were collected from 3 hospitals in the Kingdom of Saudi Arabia from August 1999 through to November 1999. Samples of a CPF were collected for comparison. All samples were analyzed for nutritional content, microbial quality (aerobic plate counts, coliform counts, microorganism growth) and physical characteristics (viscosity, osmolality). RESULTS: The nutrient content of BTF varied significantly within and between sites. The average intra site variability for all sites ranged from 16-50%. The average variability of the CPF was 4-7%. Between sites, the mean concentration of most nutrients varied by 2-3 fold. The BTF had considerable differences between actual and expected nutrient concentrations, reaching statistical significance in 12 nutrients. The measured concentration of most nutrients in the CPF was within 10% of expected values. The BTF samples had higher viscosity and osmolality than the CPF. All samples of BTF had detectable aerobic plate counts that increased significantly over 4 hours (p<0.0005). Coliform contamination varied between sites, with 100% contamination at one site. No aerobic plate counts or coliform counts were detected in the CPF samples. CONCLUSION: There is a high degree of variability in nutrient content and physical properties with BTF. Furthermore, BTF are highly contaminated, increasing the risk of nosocomial infections. For these reasons, CPF should replace BTF.

Colony Count, Microbial↗
PubMed1991

Dental caries and salivary and microbial conditions in 50-60-year-old persons.

In a group of 124 persons, 50-60 yr old, the prevalence at baseline of mutans streptococci (MS) and lactobacilli and the salivary secretion rate and buffer capacity were examined. The mean secretion rate was 1.58 mL/min with a flow rate below 1 mL/min found in 20% of the persons. A buffer capacity below end pH 5.5 was observed in 64% of the subjects. MS was not detected in 5% of the persons whereas 17% had 10(6) or more MS per ml saliva. Lactobacilli were not found in 10% of the persons while 21% had counts in excess of 10(5) CFU mL. A new examination 5 yr later in 1986 revealed no significant changes in secretion rate and buffer capacity or in the population of lactobacilli, whereas markedly elevated levels of salivary MS were found. S. sobrinus was detected in 35-37% of the persons at the two examinations. Persons with both S. mutans and S. sobrinus had more MS than persons with only S. mutans.

Buffers↗
PubMed2006

Comparison between direct microscopy and flow cytometry for rRNA-based quantification of Candidatus Accumulibacter phosphatis in activated sludge.

A comparison of the quantification of a specific microbial group in activated sludge by fluorescent in-situ hybridization, coupled with either direct microscopic counting or flow cytometry, was performed using an enhanced-biological-phosphorus-removal, sequencing-batch reactor. The population dynamics of Candidatus Accumulibacter phosphatis (Cand. A. phosphatis) was evaluated during two separate runs of the reactor. With the operational conditions used, Cand. A. phosphatis was enriched until a failure in the pH controller eliminated its ecological advantage. As a result, the comparison of quantification techniques included Cand. A. phosphatis concentrations as low as 11% and as high as 96% of the total cells in the samples. The analysis demonstrated that, regardless of the particular limitations of each technique, both provided similar results when the activated-sludge flocs were easily dispersed. However, when the activated-sludge samples contained flocs that were difficult to disperse, flow cytometry failed to provide quantitative results.

Biodegradation, Environmental↗
PubMed2006

Liming poultry manures to decrease soluble phosphorus and suppress the bacteria population.

Stabilizing phosphorus (P) in poultry waste to reduce P losses from manured soils is important to protect surface waters, while pathogens in manures are an emerging issue. This study was conducted to evaluate CaO and Ca(OH)2 for killing manure bacterial populations (pathogens) and stabilizing P in poultry wastes and to investigate the influence on soils following amendment with the treated wastes. Layer manure and broiler litter varying in moisture content were treated with CaO and Ca(OH)2 at rates of 2.5, 5, 10, and 15% by weight. All treated wastes were analyzed for microbial plate counts, pH, and water-soluble phosphorus (WSP), while a few selected layer manures were analyzed by phosphorus X-ray absorption near edge structure (XANES). A loamy sand and a silt loam were amended with broiler litter and layer manure treated with CaO at rates of 0, 2.5, 5, 10, and 15% and soil WSP and pH were measured at times 1, 8, and 29 d. Liming reduced bacterial populations, with greater rates of lime leading to greater reductions; for example 10% CaO applied to 20% solids broiler litter reduced the plate counts from 793,000 to 6500 mL-1. Liming also reduced the WSP in the manures by over 90% in all cases where at least 10% CaO was added. Liming the manures also reduced WSP in soils immediately following application and raised soil pH. The liming process used successfully reduced plate counts and concerns about P losses in runoff following land application of these limed products due to decreased WSP.

Animals↗
PubMed1994

[Microfilters within the scope of infusion therapy--possibilities and problems in retention of microbial and particle contaminants].

Contamination of parenterally applied fluids by bacterial and particulate material may contribute to the development of sepsis, multiple organ failure, and adult respiratory distress syndrome. 0.2 microns in-line filters are effective in reducing bacteria and foreign matter in the infused fluids. The rate of thrombophlebitis was demonstrated to be significantly reduced by in-line filtration. However, to date there is no definite evidence from clinical studies that these filters are effective in reducing overall morbidity and mortality. Furthermore the use of in-line filters reduces waste material and required nursing time, because the infusion systems have to be replaced every 96 hours as opposed to 24 hours without filters. In conclusion, use of 0.2 microns in-line filters in infusion therapy is cost effective and may enhance patients' safety.

Catheters, Indwelling↗
PubMed1998

[Bacterial and fungal colonization in indwelling total laryngectomy phonatory prostheses: identification of microbial agents, treatment protocol and prevention].

Today, after the erygmophonic voice, the application of phonatory prostheses is the rehabilitation strategy of choice in patients who had undergone laryngectomy. This is because the surgical procedure is simple and because they are highly successful. The main cause of complications is infection or biofouling. The present study examined the results of cultures taken from phonatory prostheses in 15 laryngectomy patients. The dominating strains of the bacteria and fungi were tested to determine their sensitivity to various pharmacological treatments. By working up and applying a preventive and treatment protocol to reduce prosthetic infections, the average duration of these devices, and thus their functionality, has been increased by approximately 50% bringing it from 6 to 9 months.

Anti-Bacterial Agents↗
PubMed1991

Biphasic kinetics of bacterial killing by quinolones.

The early phases of the bactericidal dynamics of three quinolones against two Escherichia coli strains were studied. Four concentrations of nalidixic acid, pefloxacin and ofloxacin were tested against each strain. In each case biphasic killing of bacteria was observed after a lag phase, and a biexponential model of microbial death could be fitted to the data. A direct relationship existed between the length of the lag phase and the drug concentration. The other parameters of the model appeared to be either strain-dependent, drug-dependent or both, and were characterised by narrow fluctuations. The degree of killing was always higher for ofloxacin. A paradoxical effect seemed to exist for nalidixic acid and pefloxacin in that survival was greater in the presence of 5 x MIC than in the presence of 3 x MIC. It was clear that ofloxacin did not act in the same way as nalidixic acid and pefloxacin. The study illustrated the relevance of mathematical modelling to investigations of the bactericidal effects of antibiotics.

Colony Count, Microbial↗
PubMed1993

The colonization of solid PVC surfaces and the acquisition of resistance to germicides by water micro-organisms.

Six common water bacteria were examined for their ability to colonize polyvinyl chloride (PVC) surfaces, survive various germicidal treatment, and re-establish themselves in sterile distilled water (SDW). For each test, two 30.4 cm PVC pipes attached to a 90 degrees PVC elbow were filled with 600 ml of distilled water inoculated with either Pseudomonas aeruginosa, Ps. cepacia, Ps. mesophilica, Acinetobacter anitratus, Mycobacterium chelonae or M. chelonae var. abscessus. After 8 weeks contaminated water was removed and the pipes were exposed to 600 ml of 1:213 iodophor disinfectant (ID), 1:128 phenolic detergent (P), 1:256 quaternary ammonium compound (QA), stock iodophor antiseptic (IA), 2% formaldehyde (F), 10-15 ppm free chlorine (C), 2% glutaraldehyde (G) and 70% ethanol (E). These germicides were periodically sampled, neutralized and examined for surviving organisms. After exposure for 7 d the germicides were removed and each pipe was refilled with SDW. This was assayed at 7 d intervals to determine microbial re-establishment. Samples were removed during microbial conditioning and examined by scanning electron microscopy (SEM). Pseudomonads were isolated directly from ID, QA, C, P and F, and mycobacteria from QA, IA, ID, P, G, C and F. Pseudomonas aeruginosa and Ps. cepacia survived in PVC pipes after 7 d of exposure to P, ID and C; Ps. mesophilica, after C and ID; and both mycobacteria, after C. SEM examination of PVC remnants revealed bacterial attachment and formation of extracellular material with embedded cells. These studies show that common water bacteria can attach and colonize the interior surface of PVC pipes and develop significant resistance to the action of certain germicides.(ABSTRACT TRUNCATED AT 250 WORDS)

Acinetobacter↗
PubMed1999

Microbiologic aspects of dental plaque and dental caries.

Dental plaque is an example of a microbial biofilm with a diverse microbial composition; it is found naturally on teeth and confers advantages to the host, for example, by preventing colonization by exogenous, and often pathogenic, micro-organisms. In individuals with a high frequency sugar diet, or with a severely compromised saliva flow, the levels of potentially cariogenic bacteria (acid-producing and acid-tolerating species) can increase beyond those compatible with enamel health. This article discusses antimicrobial strategies to control dental caries, including; reducing plaque levels, in general or specific cariogenic bacteria in particular, by antiplaque or antimicrobial agents; reducing bacterial acid production by replacing fermentable carbohydrates in the diet with sugar substitutes, or by interfering with bacterial metabolism with fluoride or antimicrobial agents.

Anti-Bacterial Agents↗
PubMedDate not supplied

Design, development and qualification of a microbiological challenge facility to assess the effectiveness of BFS aseptic processing.

A programme of work has been initiated to further the understanding of the impact of the environment surrounding a Blow/Fill/Seal (BFS) machine upon the microbiological quality of processed product. A dedicated facility (Challenge Room) has been constructed and qualified to provide for the production and containment of dispersions of micro organisms in air of a room housing an operating BFS machine of a given style and configuration. The facility achieves homogeneous distribution of generated dispersions throughout the Challenge Room air, including that within and close to the critical area in which aseptic BFS operations occur. Generated microbial dispersions can be maintained in the room over extended time periods (up to 600 min) at a desired concentration within the range 10(1) to 10(7) cfu m(-3). They can also be produced employing different cell types, including bacterial endospores, Gram-positive and Gram-negative vegetative cells and yeast cells. Effective containment of dispersions is achieved while 'cards of product' (vials in sets) are conveyed from the Challenge Room to an adjacent Packing and Storage Area. Decontamination of the room and the housed BFS machine is accomplished through exposure to chlorine dioxide gas at a concentration of 1.0 mg dm(-3) for 120 min at room temperature (approximately 23 degrees C).

Air Microbiology↗
PubMed1991

[Microbiological quality of mechanically deboned beef].

Microbial quality of mechanically deboned beef (MDB), which was obtained by the discontinuous hydraulic horizontal separator, type Inject-Star (firm LASKA, Austria), was analyzed for the presence of indicatory microorganisms (coliforms and enterococci), pathogenic and conditionally pathogenic microorganisms. The basic microbial parameters have been determined separately for MDB of 1st, 2nd degrees as well as for average daily samples from one collecting vessel. Apart from it, also a raw material (beef from flesh bones intended for separation) and salt MDB after 24 hrs storing in chiller before working it into meat products were examined by the same way. From our results it follows that the number of all microorganisms observed in MDB of 1st degree was lower than that of 2nd degree. During the separation process the increase of microbial parameters compared with those in initial raw material occurred by 1-2 radices and following subsequent salting and storing in chiller there was a repeated decrease by 1 radix (with exception of the number of Staphylococci remaining unchanged). The change in the amount of microflora present was also influenced by season--in summer there was an increase by about 1 radix. From the view point of food hygiene the finding of salmonellas and the presence of large number of Staphylococci including Staphylococcus aureus on average 10(5).g-1 as well as the presence of wide extent of conditionally pathogenic microorganisms from the family of Enterobacteriaceae, especially from genera Proteus, Providencia, Morganella and Citrobacter are of great importance.

Animals↗
PubMed2005

Yeast and lactic acid flora of tej, an indigenous Ethiopian honey wine: variations within and between production units.

A total of 200 samples of tej, an indigenous Ethiopian honey wine, were collected from ten production units at different production times. The samples were analysed for their microbial flora. Mean counts of aerobic mesophilic bacteria and aerobic spores for the different production units were <3 log cfu/ml. Coliforms and other members of Enterobacteriaceae were below detectable levels basically due to the low pH of the samples (<4.0). Yeasts were among the dominant micro-organisms in all samples with mean counts of 6 log cfu/ml for all production units. Over 25% of the yeast isolates belonged to Saccharomyces cerevisiae followed by Kluyvermyces bulgaricus (16%), Debaromyces phaffi (14%) and K. veronae (10%). Yeast counts showed significant variation within samples of a production unit (CV>10%) and difference in counts among all samples was also significant (P<0.01). The lactic acid bacteria had counts of 6 log cfu/ml with a significant variation within samples of a production unit (CV>10%) or among all samples (P<0.01). In most production units, the heterolactics had higher counts than the homolactics. The lactic flora consisted of Lactobacillus, Streptococcus, Leuconostoc and Pediococcus species. The lactobacilli were, however, the most frequently encountered groups. In most of the samples, the lactic flora was dominated by two (49.5%) or three (46%) groups of lactic acid bacteria.

Colony Count, Microbial↗
PubMed2004

Microbial structural diversity estimated by dilution-extinction of phenotypic traits and T-RFLP analysis along a land-use intensification gradient.

The present work tested whether the relationship between functional traits and inoculum density reflected structural diversity in bacterial communities from a land-use intensification gradient applying a mathematical model. Terminal restriction fragment length polymorphism (T-RFLP) analysis was also performed to provide an independent assessment of species richness. Successive 10-fold dilutions of a soil suspension were inoculated onto Biolog GN(R) microplates. Soil bacterial density was determined by total cell and plate counts. The relationship between phenotypic traits and inoculum density fit the model, allowing the estimation of maximal phenotypic potential (Rmax) and inoculum density (KI) at which Rmax will be half-reduced. Though Rmax decreased with time elapsed since clearing of native vegetation, KI remained high in two of the disturbed sites. The genetic pool of bacterial community did not experience a significant reduction, but the active fraction responding in the Biolog assay was adversely affected, suggesting a reduction in the functional potential.

Bacteria↗
PubMed1996

Antimicrobial activities of iodinated polystyrene derivatives.

The antimicrobial activities of insoluble halogenated acetamidomethy1-styrene polymers (prepared by covalent bonding of iodine to polystyrene) were assessed as were the factors determining antimicrobial efficacy. The most active materials were selected from chlorinated or iodinated polymers. Antimicrobial activities were assessed for Escherichia coli (ATCC 25922; American Type Culture Collection, Rockville, MD, U.S.A.), Saccharomyces cerevisiae, and Candida albicans by determining time-course changes in microbial counts in vitro. A 2-iodoacetamidomethylstyrene polymer (No.6-I:-CH2I) was found to have the greatest antimicrobial activity against both bacteria and fungi. No.6-I is the first antimicrobial material that did not make an inhibition hollow in the conventional diffusion test or for which conjugated iodine showed antibacterial activity. This material can be introduced into styrene units on the surface of devices by chemical modification. This material was most active at 37 degrees C. For coated dishes, antimicrobial activity depended on the depth or swollen character of the reactive layer. NO.6-I requires not only a minimum width of polymer layer, but also frequent contact with microbes to have an antimicrobial effect. No.6-I is valuable as a new material because it has strong antimicrobial activity by itself but does not release active iodine. This material is expected to have various applications in implantable clinical devices.

Anti-Infective Agents, Local↗
PubMed2003

Detection and quantitative estimation of Dehalococcoides spp. in a dechlorinating bioreactor by a combination of fluorescent in situ hybridisation (FISH) and kinetic analysis.

The unique capacity of Dehalococcoides ethenogenes of completely dechlorinating the common groundwater pollutant tetrachloroethene (PCE) to the harmless ethene makes this microorganism very attractive for application in natural or engineered bioremediation systems. In this study, the qualitative and quantitative determination of Dehalococcoides spp. in a lab-scale bioreactor was performed based on the combination of fluorescent in situ hybridisation (FISH) for specific detection, and kinetic batch tests at non-limiting hydrogen and PCE concentration for quantitative determination. The dechlorinating bioreactor was operated at a high and constant PCE loading rate of 255 micromol PCE [g volatile suspended solids (VSS)](-1) day(-1). Pale coccoid cells resembling the distinctive morphotype of D. ethenogenes were present in the microbial culture. These cocci hybridised with both eubacterial probes and the Dhe1259t probe recently designed for detecting Dehalococcoides spp. Positive hybridisation was also observed when the DHC1377 reverse primer was used as a specific probe and applied to the dechlorinating microbial consortium. The maximum dechlorination rate obtained under non-limiting hydrogen and PCE concentrations was 3.22 +/- 0.08 mmol Cl(-) l(-1 )day(-1). From the specific activity of D. ethenogenes [i.e. 0.055 +/- 0.008 mmol Cl(-) (mg VSS)(-1) day(-1)], as reported from pure culture study, this observed maximum rate corresponded to a concentration of this bacterium in the mixed liquor of the bioreactor of 59.0+/-10.4 mg VSS.l(-1) (41.5+/-11.2% of overall VSS). This calculated relative abundance of D. ethenogenes was in agreement with the percentage of methanol (in terms of reducing equivalents) channeled to reductive dechlorination (approximately 30%) supporting the assumption that most reductive dechlorination was actually due to this microorganism.

Biodegradation, Environmental↗