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PubMed2001

Hot water immersion to eliminate Escherichia coli O157:H7 on the surface of whole apples: thermal effects and efficacy.

The effect of hot water immersion on both the reduction of Escherichia coli O157:H7 on the apple surface and internal temperatures of the apple was assessed in this study. Microbial reductions were measured experimentally, whereas internal temperatures were calculated through a mathematical analysis of experimental heat transfer data obtained from the apples. A method was developed to provide a purely surface-based inoculation of E. coli O157:H7. Rinsing produced no reduction, and treatments at 80 and 95 degrees C produced reductions of more than 5 logs in 15 s or less. The heat transfer analysis based on experimental data was used to calculate surface heat transfer coefficients and predict temperatures throughout the apple. The analysis indicated a low heat transfer rate. Although it reduces thermal degradation, a low heat transfer rate precludes thermal-based reduction of any internalized microorganisms.

Colony Count, Microbial↗

PubMed2006

Inactivation of microorganisms in milk and apple cider treated with ultrasound.

Nonthermal technologies are emerging as promising alternatives to heat treatment for food processing. Ultrasound, defined as sound waves with a frequency greater than 20 kHz, has proven bactericidal effects, especially when combined with other microbial-reduction strategies such as mild heating. In this study, ultrasound treatment (sonifier probe at 20 kHz, 100% power level, 150 W acoustic power, 118 W/cm2 acoustic intensity) with or without the effect of mild heat (57 degrees C) was effective at reducing microbial levels in raw milk, Listeria monocytogenes levels inoculated in ultrahigh-temperature milk, and Escherichia coli O157:H7 in apple cider. Continuous flow ultrasound treatment combined with mild heat (57 degrees C) for 18 min resulted in a 5-log reduction of L. monocytogenes in ultrahigh-temperature milk, a 5-log reduction in total aerobic bacteria in raw milk, and a 6-log reduction in E. coli O157:H7 in pasteurized apple cider. Inactivation regressions were second-order polynomials, showing an initial period of rapid inactivation, eventually tailing off. Results indicate that ultrasound technology is a promising processing alternative for the reduction of microorganisms in liquid foods.

Animals↗

PubMed2005

Presence of Actinobacillus actinomycetemcomitans on the Community Periodontal Index (CPI) teeth in periodontally healthy individuals.

The aim of this study was to compare the prevalence of Actinobacillus actinomycetemcomitans (A. actinomycetemcomitans) located at Community Periodontal Index (CPI) teeth versus randomly selected teeth to determine if the CPI teeth are representative of this bacteria subgingival colonization in periodontally healthy young individuals. Forty-four individuals between 18 and 27 years of age were included in the study (mean age 23.11 +/- 2.91 years). Pooled subgingival plaque samples were collected with paper points from the mesio-buccal aspect of the CPI teeth (10 teeth for adults and 6 teeth for persons under 20 years of age) and transported in reduced Ringer's solution to the culture medium. Sixty days following the first microbial analysis, new pooled microbial samples were obtained from the mesio-buccal aspect of 10 or 6 randomly selected teeth. The presence of A. actinomycetemcomitans was determined using a selective culture medium. Microbiological data were assessed by the Wilcoxon test (p < 0.05). A border line significance (p=0.51) was observed between CPI teeth and randomly selected teeth in terms of detecting the subgingival occurrence of A. actinomycetemcomitans. CPI teeth showed to be representative of A. actinomycetemcomitans subgingival colonization. Therefore, these results suggest that in periodontally healthy young individuals, CPI teeth could be an appropriate source of samples for the subginginval detection of this pathogen.

Adolescent↗

PubMed1996

Caries prevalence and salivary and microbial conditions in 88-year-old Swedish dentate people.

As part of a comprehensive investigation of 88-year-old people, caries prevalence, stimulated salivary secretion rate, buffer capacity, and the prevalence of lactobacilli and mutans streptococci were studied in a subsample of 92 dentate subjects. The mean number of remaining teeth was 14.1 +/- 7.3. The DMFT was 25.2 +/- 3.0, and DF surfaces 38.3 +/- 22.7. Root caries experience was found in 85% of the subjects, with a mean root caries index of 36.6 +/- 28.5%. The men had significantly higher mean values of salivary secretion rate (2.0 +/- 1.3 ml/min) than the women (1.1 +/- 0.6 ml/min) (p < 0.001). The mean final pH of buffer capacity was 6.3 +/- 1.3. High counts of lactobacilli (> 10(5)) and mutans streptococci (> 10(6)) were found in 49% and 55% of the subjects, respectively, of whom most were denture wearers. The mean number of total mutans streptococci was higher in persons harboring both Streptococcus mutans and S. sobrinus than in subjects with only S. mutans.

Aged↗

PubMed2003

Microbial contamination of tooth brushes and their decontamination.

With the dawn of the new century, dentistry has seen a new face in the fields of diagnosis, treatment and prevention. Twenty one children were asked to brush their teeth for five days. The brushes were put in Robertson's Cooked Meat broth and cultured. Growth of Streptococcus Mutans were seen. These brushes were then placed in disinfectants such as 0.2% chlorhexidine gluconate (Gp I), 1% sodium hypochlorite(Gp II) and water (Gp III) for 24 hrs and then cultured. Disappearance of growth of microorganisms was seen in Gp I and Gp II and remnants of growth seen in Gp III. It can be concluded that the use of disinfectant is a must for every individual at regular intervals.

Child↗

PubMed1999

Effect of natural zeolite (clinoptilolite) on microbial decomposition processes in stored pig-slurry solids.

The solid fraction (SF) of pig slurry obtained in the first stage of aerobic slurry treatment was amended with 1 and 2% zeolite (clinoptilolite) and stored for 12 weeks under anaerobic conditions or with turning after 3 and 6 weeks of storage. In addition to that SF was mixed with 2% zeolite, 50% (V/V) sawdust, and both sawdust and zeolite, and stored for 6 weeks with turning after 1 and 3 weeks. Plate counts of psychrophilic, mesophilic, coliform and fecal coliform bacteria, determined during the storage, corresponded to the development of temperature in the core of the substrates. An effect of amendment of SF with zeolite and sawdust on plate counts of selected bacteria was observed, dependent on the zeolite dose. The thermophilic phase was not reached in any of the investigated substrates. The populations of fecal coliforms in the substrate amended with 1% zeolite and turned after 3 and 6 weeks decreased after 11 weeks down to 500 CFU/g substrate.

Aerobiosis↗

PubMed1999

On modeling the irregular fluctuations in microbial counts.

Daily or other periodic microbial counts in many foods, particularly ground meats, poultry, and raw milk, show an irregular fluctuating pattern. The cause of the fluctuations is the interplay of many random factors that tend to promote or inhibit microbial growth. Therefore, the actual size of a microbial population can vary randomly around a typical level or around a trend determined, for example, by seasonal variations or changing sanitary conditions. Fluctuations around a fixed level can often be modeled as a sequence of independent counts having a lognormal or other parametric distribution. The independence of the counts and the type of distribution can be established by standard statistical tests. Once selected, the distribution function can be used to estimate the probability of encountering a population in any given size range. The model can be modified to describe sequences that include zero counts, which are the result of the organisms' absence, or of the failure of the method to detect them. In the case of fluctuations around a trend, a modified version of the model can be used to estimate the probability of deviations from the trend. A more thorough modification is required in order to account for fluctuating patterns that include outbursts of appreciable duration, like those caused by massive contamination of a water reservoir.

Animals↗

PubMed1992

Microbial penetration of gloves following usage in routine dental procedures.

Unsterile polyvinyl, regular latex, and powder-free, modified latex examination gloves were evaluated following usage in routine dental procedures to assess their loss of integrity. Glove fingers were filled with a suspension of red-pigmented Serratia marcescens and drawn across the surface of tryptic soy agar plates. The appearance of red-pigmented Serratia colonies on the plates was used as an indication of glove defects. Unused, unwashed gloves taken at random from boxes served as controls. Of the gloves used in clinical procedures, 83.3% of the polyvinyl gloves, 35.0% of the regular latex gloves, and 7.5% of the powder-free, modified latex gloves allowed penetration of Serratia. Data thus suggest that advances in technology continue to develop a glove with more resistance than regular latex and vinyl gloves to routine clinical usage.

Colony Count, Microbial↗

PubMed1999

The effect of a model melanoidin mixture on faecal bacterial populations in vitro.

The Maillard reaction produces coloured, macromolecular materials (melanoidins) in a variety of foods, on heating. Significant quantities may enter the human gut on a daily basis, but there is little information on their metabolism in the human colon. As the large bowel contains a diverse population of bacteria involved in normal bowel function, it is possible that melanoidins are metabolized therein. Depending on the bacteria involved, there may be disease or health implications. The aim of the present study was to use in vitro models to determine the digestibility of melanoidins and the effect of melanoidins on colonic bacteria in the gastrointestinal tract. Melanoidins were prepared and the effects of simulated upper-gut secretions on their stability determined in a model system. The effects of faecal bacteria were also determined, in batch culture, with a combination of phenotypic and genotypic (probes) criteria being used to identify the microbial diversity involved. Simulation of peptic and pancreatic digestion showed that the melanoidins did not produce detectable amounts of low-molecular-mass degradation products. However, melanoidins affected the growth of gut bacteria during mixed culture growth. The effect was to cause a non-specific increase in the anaerobic bacteria enumerated. This in vitro study indicates that melanoidins can affect the growth of human large-bowel bacteria and serves to demonstrate possible effects that may occur in vivo. Given the large and varied number of food items that contain Maillard reaction products, this may have relevance for lower-gut health.

Adult↗

PubMedDate not supplied

Incidence of fungi in shared-use cosmetics available to the public.

A survey was conducted to assess both the potential health risk from shared-use cosmetics caused by microorganisms and the microbial efficacy of preservatives in cosmetics. Samples of 3027 shared-use cosmetic products were collected from 171 retail establishments nationwide. Fungi were present in 10.4% of the products, and 3.9% contained fungal pathogens or opportunistic pathogens. The 423 fungal isolates identified represented 33 genera and at least 69 species. A disproportionately large share of the fungal isolates were from eye products; fewer were from lip products. Pathogenic or opportunistic pathogens made up 32.2% of the fungal isolates. A slightly lower percentage of samples that contained preservatives had fungi, a fact suggesting that preservatives reduce the incidence of fungi in cosmetics. Results of this survey indicate potential microbiological problems concerning the safety of shared-use cosmetics.

Colony Count, Microbial↗

PubMed1994

Use of fluorochromes for direct enumeration of total bacteria in environmental samples: past and present.

Understanding the role of bacteria in microbial food webs is intimately connected to the methods applied in the direct enumeration of bacteria. We have examined over 220 papers describing studies in which fluorochrome staining followed by epifluorescent microscopic direct counts was used to estimate total bacterial abundances. In this review, we summarize patterns in the use of 3,6-bis[dimethylamino]acridinium chloride (acridine orange) and 4',6-diamidino-2-phenylindole (DAPI), the two stains most frequently used in bacterial enumeration. The staining of samples with these fluorochromes, followed by filtration and direct counting of bacterial cells on filter surfaces, has become routine over the past 10 years. We examine trends in features of the standard direct count methods, such as sample preservation and preparation techniques, membrane filter types used, applied stain concentrations, duration of staining, and counting strategies, in relation to the types of samples being examined. The high variability in bacterial counts observed within similar sample types may be partially accounted for by differences in methods. Synthesizing review findings, we include a recommended method for the direct enumeration of bacteria in environmental samples.

Bacteria↗

PubMed1989

Shelf-life of vacuum-packed cooked ring sausages at different chill temperatures.

Microbiological and sensory changes in 313 vacuum-packed cooked ring sausages from 28 different production runs and stored at 2, 4, 8 or 12 degrees C were monitored as a function of time. The sensory scores started to decrease at a level of approx. 10(7) lactobacilli/g. The judges began considering the samples unfit for human consumption when the lactobacilli counts were between 10(7) and 10(8) cfu/g; above a level of 10(8) cfu/g most of the samples were deemed unfit. At 2 degrees C, however, spoilage did not always seem to be microbiological, and four out of six different production runs were deemed unfit without any marked increase in microbial counts. In such cases, the judges described the sensory defects as a 'musty' rather than a sour aroma and taste. The sausages were deemed unfit when the lactobacilli were in a stationary growth phase which was considerably later than the point when the bacterial counts exceeded 10(7) cfu/g. The mean length of this delay was 30, 19, 16 and 7 days at 2, 4, 8 and 12 degrees C, respectively. The average shelf-lives were 55, 43, 29 and 17 days at 2, 4, 8 and 12 degrees C, respectively. The dependence of shelf-life on temperature can be formulated as follows: Shelf-life = 10(1.835 - 0.048 X temperature) The maximal shelf-life of this product, including nonmicrobiological spoilage, is assessed as approx. 10-11 weeks. A lactobacilli count greater than 10(7) cfu/g indicates that either the spoilage process has started or the product is already spoiled. When the lactobacilli count exceeds 10(8) cfu/g it is highly probable that the sausage sample is unacceptable.

Cold Temperature↗

PubMed2001

Comparison of a range of green fluorescent protein-tagging vectors for monitoring a microbial inoculant in soil.

Two new transposon-based tagging vectors have been constructed using the gfp marker gene under control of either constitutive or inducible promoters. The two vectors, along with the established pUTminiTn5gfp were used to tag a diesel-degrading Pseudomonas strain. Tagged strains were obtained that were not affected in terms of their growth or ability to use diesel as a carbon source. The transposon tags were stably maintained in the strains without selection and provided visible fluorescence as colonies or single cells in suspension. Tagging did not impede the survival of tagged Pseudomonas aeruginosa GP41B strains in diesel-contaminated soil microcosms. The tagged strains were easily recovered from the microcosms after a 3-month period. The tagging of bacteria with gfp using either native or introduced constitutive/inducible promoters is an effective and easy way to monitor their survival in soil.

Colony Count, Microbial↗

PubMed2006

Prevalence study of Legionella spp. contamination in ferries and cruise ships.

BACKGROUND: In the last years, international traffic volume has significantly increased, raising the risk for acquisition of infectious diseases. Among travel-associated infections, increased incidence of legionellosis has been reported among travellers. Aim of our study was: to describe the frequency and severity of Legionella spp. contamination in ferries and cruise ships; to compare the levels of contamination with those indicated by the Italian ministerial guidelines for control and prevention of legionellosis, in order to assess health risks and to adopt control measures. METHOD: A prevalence study was carried out on 9 ships docked at the seaports of northern Sardinia in 2004. Water samples were collected from critical sites: passenger cabins, crew cabins, kitchens, coffee bars, rooms of the central air conditioning system. It was performed a qualitative and quantitative identification of Legionella spp. and a chemical, physical and bacteriological analysis of water samples. RESULTS: Forty-two percent (38/90) water samples were contaminated by Legionella spp.. Positive samples were mainly drawn from showers (24/44), washbasins (10/22). L. pneumophila was isolated in 42/44 samples (95.5%), followed by L. micdadei (4.5%). Strains were identified as L. pneumophila serogroup 6 (45.2%; 19 samples), 2-14 (42.9%), 5 (7.1%) and 3 (4.8%). Legionella spp. load was high; 77.8% of the water samples contained > 10(4) CFU/L. Low residual free chlorine concentration (0-0.2 mg/L) was associated to a contamination of the 50% of the water samples. CONCLUSION: Legionella is an ubiquitous bacterium that could create problems for public health. We identified Legionella spp. in 6/7 ferries. Microbial load was predominantly high (> 10(4) CFU/L or ranging from 10(3) to 10(4) CFU/L). It is matter of concern when passengers are subjects at risk because of Legionella spp. is an opportunist that can survive in freshwater systems; high bacterial load might be an important variable related to disease's occurrence. High level of contamination required disinfecting measures, but does not lead to a definitive solution to the problem. Therefore, it is important to identify a person responsible for health safety in order to control the risk from exposure and to apply preventive measures, according to European and Italian guidelines.

Air Conditioning↗

PubMed1974

Viability of Bacillus subtilis spores exposed to space environment in the M-191 experiment system aboard Apollo 16.

During the Apollo 16 space flight, in the experiment system M-191, (microbial response to space environment) spores of Bacillus subtilis 168 were exposed to space vacuum or solar UV irradiation with a peak wavelength of 254 nm or both. The effects of these space factors on the colony-forming ability of the spores were studied. It was found (i) that space vacuum alone did not affect the survival of pre-dried spores; (ii) that space vacuum in combination with solar UV irradiation with a peak wavelength of 254 nm had a synergistic effect, which may by attributed to a UV supersensitivity of the spores during vacuum exposure. These results agreed with findings of simulation experiments on earth. It was concluded that air dried spores may survive exposure to space vacuum if shielded against solar UV irradiation.

Bacillus subtilis↗

PubMed2002

The effects of an immediately pre-surgical chlorhexidine oral rinse on the bacterial contaminants of bone debris collected during dental implant surgery.

Dental implant surgery produces bone debris that can be used in the "simultaneous augmentation" technique. Although this debris is contaminated with oral bacteria, a stringent aspiration protocol has been shown to reduce the levels of contamination. Chlorhexidine mouthrinse is a well-proven antibacterial rinse that has been shown to reduce infectious complications associated with dental implants. This study examined the effect of pre-operative rinsing with a 0.1% chlorhexidine digluconate mouthrinse on the bacterial contaminants present in collected bone debris bone (CBD). Twenty partially edentate patients were randomly allocated into equal groups and underwent bone collection using the Frios Bone Collector (FBC) during the insertion of two dental implants. In group T a pre-operative chlorhexidine rinse was used, whilst in group C sterile water was used. For both groups, a stringent bone collection protocol was used. Bone samples were immediately transported for microbial analysis. Colonial and microscopic morphology, gaseous requirements and identification kits were utilised for identification of the isolated microbes. Thirty-nine species were identified including a number associated with disease, in particular Actinomyces odontolyticus, Clostridium bifermentans, Prevotella intermedia, and Propionibacterium propionicum. Samples from group T (chlorhexidine mouthrinse) yielded significantly fewer organisms (P < 0.001) than in group C (sterile water mouthrinse). Gram-positive cocci dominated the isolates from both groups. It is concluded that if bone debris is to be used for the purpose of immediate simultaneous augmentation, a preoperative chlorhexidine mouthrinse should be utilised in conjunction with a stringent aspiration protocol to reduce further the bacterial contamination of CBD.

Actinomyces↗

PubMedDate not supplied

Microbial contamination of toothbrushes and their decontamination.

PURPOSE: The objective was to determine the level of contamination of toothbrushes by mutans streptococci using microbiological identification, to access the bacterial contamination using scanning electron microscopy (SEM) and to evaluate the efficacy of two toothbrush disinfectants. METHODS: Nineteen children used their toothbrushes once a day, for five consecutive days. The toothbrushes were then immersed into disinfectant solutions for 20 h: Group I--0.12% chlorhexidine gluconate; Group II--1% sodium hypochlorite; Group III--sterile tap water. They were then placed into test tubes containing CaSa B, for 3 to 4 days at 37 degrees C. The number of MS cfu was counted and the toothbrushes were submitted to SEM analysis. RESULTS: There was no bacterial growth in Groups I and II; Group III showed MS growth (range, 21 to 120 cfu). Scanning electron microscopy showed biofilm formation on toothbrush bristles. CONCLUSION: Immersion in 0.12% chlorhexidine gluconate and 1% sodium hypochlorite are efficient methods for toothbrush disinfection.

Anti-Infective Agents, Local↗

PubMed2001

Improved methods for the enumeration of heterotrophic bacteria in bottled mineral waters.

At this time the European Union regulations require that the heterotrophic plate counts (HPC) of mineral waters be assessed at two recovery temperatures: 22 degrees C for 72 h and 37 degrees C for 24 h. This procedure is time consuming and expensive. Development of new rapid methods for microbiological assessment of the microbial flora in the bottled water is an industry-driven need. The objectives of this work were to develop a method for the HPC that utilises only one recovery temperature and one incubation period and evaluate the use of, the LIVE/DEAD(R) BacLight Bacterial Viability Kit, 5-cyano-2,3-ditotyl tetrazolium chloride (CTC) and impedance methods to enumerate viable bacteria in bottled mineral water. Results showed that incubation at 30 degrees C could be used instead of incubation at 22 degrees C and 37 degrees C. Good correlation exists between counts at 30 degrees C and counts at 22 degrees C (r>0.90) and all the pathogens important in mineral water analyses grow similarly at 30 degrees C and 37 degrees C during 24 h. It was demonstrated that impedance methods might be useful to the mineral water industry as a rapid indicator of microbiological quality of the water. Results obtained with BacLight and CTC were similar to those obtained with plate counts.

Bacteria↗