Changes in microflora of the cloaca and oviduct of hens after intracloacal or intravaginal inoculation with Salmonella enteritidis

Quantitative and qualitative microbiological examination was carried out on cloacal and oviductal contents pre- and postinfection with Salmonella enteritidis (SE) intracloacally or intravaginally. Before inoculation with SE, the means +/- standard deviation (SD) of total bacterial counts, anaerobic bacterial counts, and aerobic bacterial counts in the cloaca were log10 7.7 +/- 0.7, 7.4 +/- 0.2, and 6.9 +/- 0.8 colony-forming units (CFU)/g, respectively. The predominant bacteria were Bacteroidaceae, Lactobacillus, and Escherichia coli. Before inoculation with SE, the means +/- SD of total bacterial counts, anaerobic bacterial counts, and aerobic bacterial counts in the vagina were log10 5.7 +/- 1.4, 5.5 +/- 1.3, and 3.6 +/- 2.7 CFU/g, respectively. Bacteroidaceae and Lactobacillus were predominant. Following inoculation with SE, only the cloacal population of Lactobacillus in hens inoculated intracloacally was significantly increased compared to that before the inoculation. Other indigenous microflora were stable even after the inoculation. In the uterus, very few bacteria, Lactobacillus and Staphylococcus, were isolated. Five of 20 eggs (25%) from hens inoculated with SE intravaginally were positive for SE, whereas no SE was recovered from 22 eggs in hens inoculated with SE intracloacally. SE was recovered from the uterus after intravaginal inoculation with SE and from the vagina after intracloacal inoculation with SE. Contamination may ascend from the cloaca into the lower parts of the oviduct and subsequently contaminated eggs may occur.     

Application of antisera raised against sulfate-reducing bacteria for indirect immunofluorescent detection of immunoreactive bacteria in sediment from the German Baltic Sea

Polyclonal rabbit antisera raised against sulfate-reducing bacteria (SRB) could detect several distinct populations of bacteria in sediment from the German Baltic Sea. The depth distribution of immunoreactive bacteria was determined by an indirect immunofluorescence filter method. Anti-Desulfovibrio desulfuricans DSM 1926 serum showed maximum bacterial numbers at a depth of 18 cm, with a concentration of 60 x 10(6) cells cm-3. With anti-Desulfovibrio baculatus DSM 2555 serum, counts were highest at the same depth, approaching 0.7 x 10(6) cells cm-3. Other significantly smaller populations were observed. Anti-SRBStrain 1 (lactate,vibrio) maxima were at 0 to 4 cm and at 17 to 18 cm. Anti-SRBStrain 2 (lactate,vibrio) serum showed several local maxima. Anti-SRBStrain 3 (lactate,oval) serum detected one single peak at a depth of 10 to 12 cm. Also determined were rates of sulfate reduction, total bacterial counts by acridine orange staining, and the viable counts by dilution series on anaerobic lactate medium. The total bacterial counts were highest (180 x 10(6) cells cm-3) at 3 to 4 cm and dropped to 24 x 10(6) cells cm-3 at 10 to 11 cm but showed additional local maxima reaching 140 x 10(6) cells cm-3 at a depth of 17 to 18 cm. Viable counts probable number) were above 10(5) CFU cm-3 at 0 to 3.6 cm but remained below 10(3) CFU at 7.2 to 18 cm. The sulfate reduction rate was maximal (107 nmol cm-3 day-1) at a depth of 1 to 2 cm, dropped to 10 nmol cm-3 day-1 at 12 to 13 cm, and reached 38 nmol cm-3 day-1 at 17 to 18 cm.     

Emissions and immisions of bio-aerosols from a duck fattening unit

In a field study emissions and immissions (receptor exposition) of bioaerosols emitted from and near a duck fattening house (25 m distance) were investigated. Within the livestock building mean concentrations of 3,342,289 CFU m-3 for airborne total mesophilic bacteria were determined. Total dust and endotoxin yields were 1.9 mg m-3 and 7,132.4 ng m-3, respectively. Additionally, enterobacteria, mesophilic and thermotolerante fungi as well as mesophilic actinomycetes were detectable. Measurements of immissions have shown, that downwind in the rear of the house a mean total germ concentration of 10,007 CFU m-3 was measurable in contrast to the upwind side of the building, where no airborne mesophilic bacteria were found. Higher concentrations downwind were generally determined for total dust, mesophilic fungi and actinomycetes, too, but not so for endotoxins. A supporting application of a numeric dispersion model confirmed the immissions for total mesophilic bacteria near by the duck fattening house. From this viewpoint immission predictions can be made in future for varying input data, i.e. wind conditions, of different components of bioaerosols.     

Quantitation of bacteria in blood of typhoid fever patients and relationship between counts and clinical features, transmissibility, and antibiotic resistance

Salmonella typhi was isolated from 369 and Salmonella paratyphi A was isolated from 6 of 515 Vietnamese patients with suspected enteric fever. Compared with conventional broth culture of blood, direct plating of the buffy coat had a diagnostic sensitivity of 99.5% (95% confidence interval [CI], 97.1 to 100%). Blood bacterial counts were estimated by the pour plate method. The median S. typhi count in blood was 1 CFU/ml (range, <0.3 to 387 CFU/ml), of which a mean of 63% (95% CI, 58 to 67%) were intracellular. The mean number of bacteria per infected leukocyte was 1.3 (interquartile range [IQR], 0.7 to 2.4) CFU/cell (n = 81). Children (< 15 years old; n = 115) had higher median blood bacterial counts than adults (n = 262): 1.5 (range, <0.3 to 387) versus 0.6 (range, <0.3 to 17.7) CFU/ml (P = 0.008), and patients who excreted S. typhi in feces had higher bacteremias than those who did not: a median of 3 (range, <0.3 to 32) versus 1 (range, <0.3 to 68) CFU/ml (P = 0.02). Blood bacterial counts declined with increasing duration of illness (P = 0.002) and were higher in infections caused by multidrug-resistant S. typhi (1.3 [range, <0.3 to 387] CFU/ml; n = 313) than in infections caused by antibiotic-sensitive S. typhi (0.5 [range, <0.3 to 32] CFU/ml; n = 62) (P = 0.006). In a multivariate analysis this proved to be an independent association, suggesting a relationship between antibiotic resistance and virulence in S. typhi.     

Evaluation of Nutrient Release from Sediments of Artificial Lake

This study examined nutrient fluxes between sediment and water with a laboratory-scale benthic chamber. This research targeted an artificial lake that had undergone water-quality problems. Two sites at Lake Asan, Site A in the vicinity of the dam and Site B at the inflow of the lake, were selected and characteristics of the sediments and their influence on the water quality of the lake were evaluated. Most of the inorganic phosphorus in the study area was in the form of apatite and nonapatite phosphorus (91.9% of Site A, 83.3% of Site B). Site B, with a fast-stream velocity, had larger particle size, smaller nutrient level, and smaller amounts of inorganic phosphorus than Site A. The benthic chamber experiment showed that overall fluxes of Site A were as follows: ammonia is 0.003??μmol?cm-2?day-1, nitrate is -0.067??μmol?cm-2?day-1, and phosphate is 1.049??nmol?cm-2?day-1. Site B showed an increase in phosphate concentration after a dissolved oxygen (DO) drop (<3??mg/l), which resulted in smaller negative nitrate fluxes (-0.043??μmol?cm-2?day-1), larger positive ammonia (0.137??μmol?cm-2?day-1), and larger phosphate fluxes (2.120??nmol?cm-2?day-1) than at Site A. The movement of nutrients at the sediment-water interface was more sensitive to environmental conditions such as DO than other factors, such as sediment characteristics and chemical forms of nutrients. On the basis of the fluxes obtained from the benthic chamber, positive values are estimated for both phosphorus and nitrogen release rates. This indicates that during the sampling period sediment acted as a source of nitrogen as well as phosphorus to the overlying waterbody.     

Effects of lactobacilli on yeast-catalyzed ethanol fermentations

Normal-gravity (22 to 24 degrees Plato) wheat mashes were inoculated with five industrially important strains of lactobacilli at approximately 10(5), approximately 10(6), approximately 10(7), approximately 10(8), and approximately 10(9) CFU/ml in order to study the effects of the lactobacilli on yeast growth and ethanol productivity. Lactobacillus plantarum, Lactobacillus paracasei, Lactobacillus #3, Lactobacillus rhamnosus, and Lactobacillus fermentum were used. Controls with yeast cells but no bacterial inoculation and additional treatments with bacteria alone inoculated at approximately 10(7) CFU/ml of mash were included. Decreased ethanol yields were due to the diversion of carbohydrates for bacterial growth and the production of lactic acid. As higher numbers of the bacteria were produced (depending on the strain), 1 to 1.5% (wt/vol) lactic acid resulted in the case of homofermentative organisms. L. fermentum, a heterofermentative organism, produced only 0.5% (wt/vol) lactic acid. When L. plantarum, L. rhamnosus, and L. fermentum were inoculated at approximately 10(6) CFU/ml, an approximately 2% decrease in the final ethanol concentration was observed. Smaller initial numbers (only 10(5) CFU/ml) of L. paracasei or Lactobacillus #3 were sufficient to cause more than 2% decreases in the final ethanol concentrations measured compared to the control. Such effects after an inoculation of only 10(5) CFU/ml may have been due to the higher tolerance to ethanol of the latter two bacteria, to the more rapid adaptation (shorter lag phase) of these two industrial organisms to fermentation conditions, and/or to their more rapid growth and metabolism. When up to 10(9) CFU of bacteria/ml was present in mash, approximately 3.8 to 7.6% reductions in ethanol concentration occurred depending on the strain. Production of lactic acid and a suspected competition with yeast cells for essential growth factors in the fermenting medium were the major reasons for reductions in yeast growth and final ethanol yield when lactic acid bacteria were present.     

The kidneys in aging]

In this study, we investigated indoor air quality and symptoms of respiratory illness in 264 nursing workers at 28 day-care centers in Taipei. Geometric mean concentrations of indoor and outdoor bacteria were 735 colony-forming units in air (CFU/m3) and 384 CFU/m3, respectively. In addition, geometric mean concentrations of indoor and outdoor fungi were 1,212 CFU/m3 and 1,032 CFU/m3, respectively. Aspergillus, Cladosporium, and Penicillium-microfungi that occurred most commonly-were found indoors and outdoors. Geometric mean concentrations of house dust mite allergens, Der p I and Der p V, were 58 ng/g dust and 14 ng/g dust, respectively. In addition, the observed high prevalence of dampness or mold problems in the day-care centers indicated that dampness was very common in this subtropical region. We found a significant relationship between dampness and work-related sick building syndrome in the day-care-center workers. Furthermore, concentrations of fungi were lower in the day-care centers equipped with air conditioners/air cleaners than in centers that lacked such equipment. Also, Aspergillus was associated strongly with work-related sick building syndrome in the day-care-center workers.     

Exposure to bacteria in swine-house dust and acute inflammatory reactions in humans

Inhalation of swine-house dust may cause an acute airway inflammatory condition (organic dust toxic syndrome). Thirty-eight healthy subjects were exposed to swine dust while weighing swine for 3 h. We studied the correlation between acute health effects and the inhaled bacterial exposure markers peptidoglycan (the main constituent of the cell walls of gram-positive bacteria, but also present in lesser amounts in gram-negative bacteria) and lipopolysaccharides (LPS; present only in gram-negative bacteria). LPS activity in airborne dust was measured with the Limulus amebocyte lysate assay (LPS(LAL)), and the total LPS was estimated from 3-hydroxy fatty acids, which were measured with gas chromatography-mass spectrometry (GC-MS) (LPS(GC-MS)). Peptidoglycan was estimated from muramic acid measured with GC-MS. The median (25th to 75th percentile) concentration of inhalable dust was 21 (16 to 25) mg/m3. LPS(LAL) was 1.2 (0.9 to 1.4) microg/m3; LPS(GC-MS) was 3.9 (2.5 to 4.9) microg/m3; and the peptidoglycan concentration in airborne dust was 6.5 (2.7 to 13) microg/m3. All exposure markers correlated significantly with an increase in serum interleukin-6. LPS(LAL) showed the highest correlation (r2 = 0.29) and total inhaled dust the lowest (r2 = 0.09). LPS(LAL) also correlated with symptoms and with an increase in bronchial responsiveness and decrease in vital capacity (VC). Peptidoglycan, but not LPS(LAL), correlated with an increase in the blood granulocyte concentration and in body temperature. The results suggest that several microbial agents in inhaled swine-house dust may contribute to acute systemic health effects.     

Fecal Coliform Removal within a Marshland Upwelling System Consisting of Scatlake Soils

The marshland upwelling system (MUS) was installed on private camps in the Grand Bay National Estuarine Research Reserve, Moss Point, Mississippi. The system was evaluated for its effectiveness in removing fecal coliforms from settled, raw wastewater. A suite of studies was performed at flow rates of 1.9, 2.8, and 5.5 L/min and an injection frequency of 30 min every 3 h to investigate fecal coliform removal. An additional study was performed at a flow rate of 2.8 L/min and an injection frequency of 15 min every hour. Overall, the MUS consistently maintained fecal concentrations below effluent regulatory standards for shellfish harvesting waters (14 most probable number of colonies per 100 mL). Mean influent concentrations of 55,269±2,218,016 colony forming units (CFU)/100 mL were reduced to effluent counts of 2.7±14.07 CFU/100 mL (observed in the 1.5 m wells). Three- to four-log reductions in influent counts were observed over the initial 1.4 vector?m from the injection well. The overall removal followed a first-order decay relationship with respect to vector distance, resulting in removal rate constants ranging from 5.6 to 6.6/m and predicted surface concentrations approaching 0 CFU/100 mL. The 2.8 L/min for 30 min every 3 h treatment provided the best effluent quality.     

Air quality and microbiologic contamination in operating theatres

The present study concerns the air quality and microbiological contamination in two newly built operating theatres; one with laminar air flow (LAF) equipment for cardio-thoracic operations, and one with conventional ventilation for urological operations. Both theatres had an identical number of air exchanges (17/h), identical microclimatic conditions and they employed the same cleaning procedures. In the LAF-ventilated operating theatre bacterial contamination of the air was effectively reduced to less than 10 colony-forming units (CFU)/m3 in all 125 samples (1 m3 per sample) tested. In most samples, 118/125, the bacterial count was less than 5 CFU/m3, despite the presence of ten persons. The conventionally ventilated theatre reached values up to 120 CFU/m3 during the most active period of the day when approximately seven persons were present. The LAF ventilation reduced both the content of particles in the air and contamination by bacteria on the floor. In both theatres cleaning procedures had only a low impact on CFU in the air and on the floor. The use of diathermia markedly increased the level of small particles in the air, and this may influence the air quality in the operating theatres.     

Microbiological survey of a South African poultry processing plant

Bacterial populations associated with poultry processing were determined on neck skin samples, equipment surfaces and environmental samples by replicate surveys. Aerobic plate counts, Enterobacteriaceae counts, Enterobacteriaceae counts and Pseudomonas counts were performed by standard procedures and the prevalence of Listeria, presumptive Salmonella and Staphylococcus aureus determined. Statistically significant (P < 0.05) increases in counts of all types of bacteria were obtained on product samples as a result of processing. Although bacterial counts on neck skin samples decreased by 0.3 to 0.4 log CFU g-1 after spray washing of carcasses, subsequent spinchilling and packaging of whole carcasses resulted in 0.7 to 1.2 log CFU g-1 increases. Bacterial numbers on equipment surfaces, however, decreased significantly from the "dirty" to the "clean" areas of the abattoir. Transport cages, "rubber fingers", defeathering curtains, shackles and conveyor belts repeatedly showed aerobic plate counts in excess of 5.0 log CFU 25 cm-2. Aerobic plate counts of scald tank and spinchiller water were 2 log CFU ml-1 higher than those of potable water samples. Bacterial numbers of the air in the "dirty" area were higher than those of the "clean" area. Listeria, presumptive Salmonella and Staphylococcus aureus were isolated from 27.6, 51.7 and 24.1% of all product samples, respectively, and Listeria and Staphylococcus aureus were also isolated from selected equipment surfaces.     

Rapid assessment of antibiotic effects on Escherichia coli by bis-(1,3-dibutylbarbituric acid) trimethine oxonol and flow cytometry

The effects of selected antibiotics on Escherichia coli were studied by flow cytometry with the fluorescent anionic membrane potential probe bis-(1,3-dibutylbarbituric acid) trimethine oxonol [DiBAC4(3)]. The actions of azithromycin, cefuroxime, and ciprofloxacin at five times the MIC on E. coli were compared by the traditional CFU assay and flow cytometry. Changes in viable counts of bacteria determined with DiBAC4(3) and by flow cytometry following treatment with the antibiotics showed trends similar to those found by the CFU assays. However, viable counts determined by flow cytometry following antibiotic treatment were 1 to 2 logs higher than those determined by the corresponding CFU assays. All the results obtained by flow cytometry were provided within 10 min after sampling, whereas the conventional CFU assay results took at least 18 h. The results indicated that flow cytometry is a sensitive analytical technique that can rapidly monitor the physiological changes of individual microorganisms following antibiotic action and can provide information on the mode of action of a drug. The membrane potential probe DiBAC4(3) provides a robust flow cytometric indicator for bacterial cell viability.     

Estimating Solar and Nonsolar Inactivation Rates of Airborne Bacteria

Land application of biosolids is a wide spread practice in the United States, Canada, and Western Europe. Given the potential for biosolid aerosolization during land application, both solar and nonsolar induced inactivation rate information is needed to more accurately predict the fate of bacteria in air. Pilot-scale bioaerosol reactor experiments that independently measure the solar and nonsolar (absence of solar radiation) inactivation rates of airborne Mycobacterium parafortuitum and Escherichia coli were performed. Direct fluorescent microscopy measurements for total airborne bacteria and culture-based assays were used to measure concentrations in a 1?m3 aerosol reactor that was transparent to UV-A and UV-B wavelengths, and to produce decay curves of airborne bacteria under moderate (50–60%) and high (85–95%) levels of relative humidity (RH). E. coli was more susceptible to airborne decay than M. parafortuitum at all RH levels tested. RH strongly influenced solar and nonsolar airborne inactivation rates in both bacteria. These inactivation rates for both bacteria were greatest at moderate RH levels.     

Application of the Nitritation and Anammox Process into Inorganic Nitrogenous Wastewater from Semiconductor Factory

The first full-scale nitritation and anaerobic ammonium oxidation (Anammox) processes for an inorganic wastewater of semiconductor factory were installed and performances were evaluated. Existing facilities of conventional nitrification and denitrification were retrofitted to a combination of the nitritation and Anammox process. Novel nitritation method, selective acceleration of ammonia oxidation by high concentration of inorganic carbon, was evaluated in full-scale aeration tank with carrier material. The ammonia conversion rate of the nitritation reactor was in the range of 0.27–0.48?kg?NO2-N/m3?day after start-up period, and stable nitritation was achieved for over 10 months. In an Anammox reactor, on-site cultivation of anammox bacteria was performed, and the most plausible reason for slower nitrogen conversion at the beginning was oxygen contamination into the reactor. After minimizing influence of oxygen contamination, design loading was achieved within 3 months of operation. After start-up period, stable Anammox reactions are maintained for over 10 months. The nitrogen removal rate after start-up period was in the range of 1.04–3.29?kg?N/m3?day. In combination with conventional denitrification process, soluble nitrogen in the final effluent was reduced below 8 mg/L.     

Aspects of microbiological and chemical quality of turmus, lupin seeds debittered by soaking in water

Eleven species of spherical lactic acid bacteria (LAB) belonging to the genera Leuconostoc, Lactococcus, Enterococcus and Pediococcus were the predominant microorganisms in 40 samples of turmus, ready-to-eat lupin seeds debittered by boiling and soaking in water. The average counts of the LAB in the 20 winter samples and the 20 summer samples were 7.4 and 8.7 log CFU/g, respectively. The averages of the Enterobacteriaceae counts were 5.1 and 6.6 log CFU/g, respectively, and the 11 species isolated belonged to the genera Enterobacter, Citrobacter, Escherichia and Klebsiella. The average yeast counts in winter and summer samples were 3 and 3.2 log CFU/g, respectively, and the 5 species isolated were in the genera Saccharomyces, Cryptococcus, Rhodotorula and Candida. Although Salmonella was not isolated from any sample and the Staphylococcus aureus count in all samples was < 1 log CFU/g, microbial hazards could be associated with the high Enterobacteriaceae counts and the presence of Escherichia coli. Total alkaloid concentration in 30% of the samples examined was higher than 0.02%, thus making the seeds a potential chemical hazard. Boiling the turmus directly before consumption and discarding the seeds with a bitter taste may help in avoiding some of the microbial and chemical hazards which could be associated with turmus consumption.     

Total and viable airborne bacterial load in two different agricultural environments using gas chromatography-tandem mass spectrometry and culture: a prototype study

Airborne exposure to bacterial components found in agricultural environments can lead to pulmonary inflammation. Total (viable and nonviable) bacterial load was monitored in a stable and a dairy by a new approach, gas chromatography-tandem mass spectrometry measurement of muramic acid, a component of gram positive and gram negative bacterial peptidoglycan. Also used to assess the gram negative bacterial load were 3-hydroxy fatty acids, markers of bacterial lipopolysaccharide. Culture, an established procedure for assessing the viable bacterial portion of airborne dust, served as a basis for comparison. The muramic acid and 3-hydroxy fatty acid concentrations (total C12:0, C14:0, and C16:0) showed a correlation with an R2 of 0.81. Dust and muramic acid levels also correlated. However, although relative muramic acid levels were lower in the stable than the dairy, colony forming units (CFU) were considerably higher in the stable. The total bacterial load (estimated from muramic acid values) for both the stable and dairy was also higher than would have been predicted from culture. These results suggest that nonculture based approaches and culture provide complementary but independent measurements of airborne biopollution.     

Airborne Bacteria Control Under Chamber and Test-Home Conditions

The research reported in this paper investigates the ability of a portable UV-based control device (size = 21?in.×12?in.×12?in.) to reduce airborne indoor bacteria levels to at or below outdoor ambient levels. Under controlled conditions, laboratory scale chamber (size = 48?in.×36?in.×48?in.) experiments and field scale residence experiments were conducted using the UV control device. Pure cultures of Staphylococcus aureus were grown in culture media and atomized into bioaerosols in the laboratory chamber. The airborne levels of the bacteria were sampled using a six-stage Andersen sampler containing selective culture media plates, and the levels were counted as number of colony forming units per cubic meter of air. The UV control device reduced the atomizer-generated laboratory chamber Staphylococcus aureus levels from a range of 5,000–15,000 cfu/m3 to below 120 cfu/m3 within a 2 h period. Continuous operation of the UV control device in the bedroom and bathroom of a single-resident apartment reduced the Staphylococcus aureus counts from a range of 200–1,300 to less than 200 cfu/m3. The unit cost of the prototype UV control device is estimated at $120, and the operating cost is estimated at $0.74/day.     

In vitro studies of pharmacodynamic properties of vancomycin against Staphylococcus aureus and Staphylococcus epidermidis

The bactericidal activities of vancomycin against two reference strains and two clinical isolates of Staphylococcus aureus and Staphylococcus epidermidis were studied with five different concentrations ranging from 2x to 64x the MIC. The decrease in the numbers of CFU at 24 h was at least 3 log10 CFU/ml for all strains. No concentration-dependent killing was observed. The postantibiotic effect (PAE) was determined by obtaining viable counts for two of the reference strains, and the viable counts varied markedly: 1.2 h for S. aureus and 6.0 h for S. epidermidis. The determinations of the PAE, the postantibiotic sub-MIC effect (PA SME), and the sub-MIC effect (SME) for all strains were done with BioScreen C, a computerized incubator for bacteria. The PA SMEs were longer than the SMEs for all strains tested. A newly developed in vitro kinetic model was used to expose the bacteria to continuously decreasing concentrations of vancomycin. A filter prevented the loss of bacteria during the experiments. One reference strain each of S. aureus and S. epidermidis and two clinical isolates of S. aureus were exposed to an initial concentration of 10x the MIC of vancomycin with two different half-lives (t1/2s): 1 or 5 h. The post-MIC effect (PME) was calculated as the difference in time for the bacteria to grow 1 log10 CFU/ml from the numbers of CFU obtained at the time when the MIC was reached and the corresponding time for an unexposed control culture. The difference in PME between the strains was not as pronounced as that for the PAE. Furthermore, the PME was shorter when a t1/2 of 5 h (approximate terminal t1/2 in humans) was used. The PMEs at t1/2s of 1 and 5 h were 6.5 and 3.6 h, respectively, for S. aureus. The corresponding figures for S. epidermidis were 10.3 and less than 6 h. The shorter PMEs achieved with a t1/2 of 5 h and the lack of concentration-dependent killing indicate that the time above the MIC is the parameter most important for the efficacy of vancomycin.     

Down-regulation of human FEN-1 gene expression during differentiation of promyelocytic leukemia cells

The presence of aflatoxin in corn and corn dust during relatively normal years and the increased risk of Aspergillus flavus infestation during drought conditions suggest that airborne agricultural exposures should be of considerable concern. Liquid extraction, thin layer chromatography, and high pressure liquid chromatography were used for the analysis of aflatoxin B1 in grain dust and bulk corn samples. A total of 24 samples of airborne dust were collected from 8 farms during harvest, 22 samples from 9 farms during animal feeding, and 14 sets of Andersen samples from 11 farms during bin cleaning. A total of 14 samples of settled dust and 18 samples of bulk corn were also collected and analyzed. The airborne concentration of aflatoxin B1 found in dust collected during harvest and grain unloading ranged from 0.04 to 92 ng/m3. Higher levels of aflatoxin B1 were found in the airborne dust samples collected from enclosed animal feeding buildings (5-421 ng/m3) and during bin cleaning (124-4849 ng/m3). Aflatoxin B1 up to 5100 ng/g were detected in settled dust collected from an enclosed animal feeding building; however, no apparent correlation was found between the airborne concentration of aflatoxin B1 and its concentration in settled dust or bulk corn. The data demonstrate that farmers and farm workers may be exposed to potentially hazardous concentrations of aflatoxin B1, particularly during bin cleaning and animal feeding in enclosed buildings.     

Development of a model for evaluation of microbial cross-contamination in the kitchen

Foods can become contaminated with pathogenic microorganisms from hands, the cutting board, and knives during preparation in the kitchen. A laboratory model was developed to determine occurrence of cross-contamination and efficacy of decontamination procedures in kitchen food-handling practices. Enterobacter aerogenes B199A, an indicator bacterium with attachment characteristics similar to that of Salmonella spp., was used. Chicken meat with skin inoculated with 10(6) CFU of E. aerogenes B199A/g was cut into small pieces on a sterile cutting board. The extent of cross-contamination occurring from meat to the cutting board and from the cutting board to vegetables (lettuce and cucumbers) subsequently cut on the board was determined. Swab samples from the cutting board, hand washings, and lettuce and cucumber samples revealed that approximately 10(5) CFU of E. aerogenes/cm2 were transferred to the board and hands and approximately 10(3) to 10(4) CFU of E. aerogenes/g to the lettuce and cucumbers. The surfaces of the cutting board and hands were treated with antibacterial agents after cutting the meat, and counts of E. aerogenes on the cutting board and vegetables (lettuce and cucumbers) were determined. Results revealed that use of the disinfectant reduced the population of E. aerogenes to almost nondetectable levels on the cutting boards. The average counts after treatment were < 20 CFU/g of vegetable and ranged from < 20 to 200 CFU per cm2 or g on the cutting board and subsequently on the vegetables. These results indicate that bacteria with attachment characteristics similar to Salmonella spp. can be readily transferred to cutting boards during food preparation and then cross-contaminate fresh vegetables if the boards are not cleaned. Application of a kitchen disinfectant can greatly reduce bacterial contamination on cutting boards.