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Due to certain properties of ultra violet rays they are primarily used for sterilizing a surface or the air. UV rays are used, among others, to disinfect isolation wards for sterile work, laminar flow cabinets, bacteriological and virusological laboratories, operating rooms, rooms in animal houses, as well as the surfaces of tables, walls or floors. The evaluation of bacterial pollution as well as the effectiveness of methods for sterilizing the air remain relevant problems in many fields, e.g. in industry, animal production, investigative laboratories or health clinics. The aim of the study was to evaluate the degree that the level of bacterial air pollution was reduced in a cabinet for microbiological investigations, sterilized by a UV lamp with a 30 watt florescent lamp. Sampl'air Lite (AES Laboratoire Chemunex) apparatus was used to gather air from the atmosphere. Samples were sampled after 15, 30, 45, 60, 75, 90, 120, 150 and 180 minutes of sterilizing the air in the cabinet with 6 repetitions for each period of irradiation. The initial and final level of the bacterial air pollution in the cabinet for microbiological investigations in relation to the period of the action of the UV rays as well as the level of bacterial reduction were evaluated. The minimal period of the action of the UV rays that ascertained a statistically significant and simultaneously the largest reduction of the bacterial air pollution was 180 minutes. With regards to all the remaining periods of irradiation no essential differences in the levels of bacterial reduction were noted, despite considerable (1.7-4.0 times) reductions of bacteria. An essential correlation was indicated between initial air pollution in the cabinets and 15, 45, and 60 minute periods of the action of UV rays. The correlation coefficients were 0.95 (p ≤ 0.01), 0.82 (p ≤ 0.05) and 0.96 (p ≤ 0.01), respectively. In the remaining cycles of the experiment the correlations were not statistically significant, and the correlation coefficients include in the interval of 0.45-0.60. There is a need, also noted by other authors, of unifying acceptable levels of microbiological air pollution for the purposes of laboratory investigations and production processes.
During 1985—1990 12 302 fodder samples were tested bacteriologically, including 303 g (24,7%) from fodder mixtures, 1585 (12,89%) from fish meal, 2905 (23,61%) from bone-meateal, 4054 (32,95%) from imported ground soya beans and peanuts 719 (5,85%) samples of protein- fat concentrate. Out of 12 302 tested samples 456 (3,71%) Salmonellae were isolated. Salmonella was most often isolated from protein-fat concentrate (14.88%) and bone-meat meal (8,57%). This bacterium was isolated with the lowest frequency from imported ground grain (0,69%) and fish meal (0,76%). The following serotypes were most commonly isolated: Salmonella choleraesuis, S. derby, S. isangi and S. typhimurium.
The aim of the study was the characterization of selected virulence markers of Shiga toxin-producing Escherichia coli originated from raw beef by the use of PCR. The identification of Stx variants (stx₂c, stx₂d, stx₂e and stx₂f) was done with the stx2 -positive E. coli strains, resulting in the detection of the stx2d gene in 13 STEC isolates out of which 3 strains also had the stx₂c gene. None of the isolates possessed the stx2f or stx2e genes. The intimin marker (γ variant) was observed in all E. coli O157:H7, whereas β variant in E. coli O26 isolates. The genotypic factors such as katP, toxB and efa1 were detected in all O157:H7 as well as in one O26 isolate. Fifteen STEC were iha-positive and five saa-positive. None of the saa-positive isolates belonged to the O157 or O26 groups. The simultaneous presence of the lpfAO₁₅₇/OI₋₁₄₁ and lpfAO₁₅₇/OI₋₁₅₄ genes was noted in 8 O157:H7 and in one O26 STEC. The lpfAO₁₅₇/OI₋₁₄₁ gene alone was present in 4 other STEC tested, including one E. coli O26. None of E. coli O157:H7 had the lpfAO113 marker that was observed in the all remaining STEC. In one isolate belonging to the E. coli O26 group, for the first time a simultaneous presence of the lpfAO₁₅₇/OI₋₁₄₁, lpfAO₁₅₇/OI₋₁₅₄ and lpfAO₁₁₃ was noted.
Medycyna Weterynaryjna
|
2010
|
tom 66
|
nr 08
s.551-554,tab.,bibliogr.
The purpose of this study was to determine the prevalence of Enterobacteriaceae and Escherichia coli in selected dairy products on the Warsaw market. Based on the presence or absence of these bacteria the hygienic quality of products was evaluated, and thus the effectiveness of the implementation of the principles of the HACCP system in force in the dairy industry plants and the regularity of the proceedings of the products on the market. Sixty-eight different dairy products were examined: fluid milk, homogenized cheeses, ripened rennet cheeses, cottage cheese type, quark cheeses, yoghurt, kefir, cream, and others. The number of Enterobacteriaceae and the MPN of E. coli were determined according to the PN-ISO 21528-1 norm. 15% of dairy products samples contained Enterobacteriaceae, and 4% of dairy products samples contained E. coli. The occurrence of Enterobacteriaceae in 33% of the fluid milk samples was observed, a level of more than 1 × 10³ in 1 mL. E. coli was not found in 10 mL samples. The highest percentage of samples containing Enterobacteriaceae and E. coli has been discovered in cheeses (quark cheeses, ripened rennet cheeses, cottage cheese type, homogenized), respectively 18% and 11%. The occurrence of Enterobacteriaceae in 14% of sheep cheeses was observed, but no sheep cheese samples contained E. coli. Of the respondent fermented milk drinks, Enterobacteriaceae occurred in only 2 samples of buttermilk. Yoghurt, kefir, cream, and sour milk does not contain Enterobacteriaceae and E. coli in 10 g. The obtained results prove that the currently stricter microbiological requirements implemented towards dairy products have contributed to the improvement in their hygienic quality.
The aim of this study was to analyse the susceptibility of Enterobacteriaceae strains isolated from food to antibiotics used in human therapy. The tests were conducted on 433 samples of raw and processed meat intended for sale. A total of 114 strains belonging to Enterobacteriaceae were isolated by the classical bacteriological technique. Escherichia, Klebsiella, Serratia, Enterobacter, Proteus, Hafnia, Citrobacter, Salmonella and Shigella were cultured from samples of beef, pork, poultry and ready-made meat products. Antibiotic susceptibility was tested by the mean of E-tests for the following antibiotics: piperacillin, piperacillin with tazobactam, cefotaxime, cefuroxime, imipenem, ceftazidime, gentamycin, tobramycin, ciprofloxacin and trimethoprim with sulfamethoxazole. Over 37% of the strains isolated were resistant to some of these antibiotics, and 34% showed resistance to at least 2 of them. Resistance was observed most frequently to cephalosporins, penicillins and trimethoprim with sulfamethoxazole, which may suggest that these antibiotics are used excessively in veterinary medicine.
Thermal resistance of L. monocytogenes strains that had been isolated from raw milk was determined in BHI broth. L. monocytogenes 1 were isolated from collected milk and L. monocytogenes 2 directly from a cow udder. Thtj strains at concentration of approximately lxl(r cell ml'1 were heated at 55°, 60° and 65°C for various periods of time. Decimal reduction times for L. monocytogenes 1 were D55 = 37.45 min, D60 = 2.63 min., Dć5 = 0.24 min. and for L. monocytogenes 2 the data were 9.73, 0.98 and 0.17 respectively. Z-values were 4.79 and 5.56° C, respectively. The reports that L. monocytogenes can survive pasteurization temperature have not been confirmed.
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