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O Pietzsch

Publications and source records attributed to O Pietzsch.

35 records · Page 2Linked to original sources
PubMed1985

Collaborative study on the isolation of salmonella from artificially contaminated milk powder.

The suitability of artificially contaminated milk powder as a substrate for salmonella reference samples and its stability under different storage conditions were studied. The need for a reconstitution step in the standard isolation method for salmonellas from milk powders was also investigated. When milk powder was examined in this way with a reconstitution step, differences in laboratory methods and/or storage times had no significant effect on the results after storage at 4 degrees C. With powder stored at room temperature there was a systematic decrease in the number of samples positive as the storage time increased. It is concluded therefore that milk powder contaminated with salmonellas should be stored at 4 degrees C. Examination of such milk powder with a reconstitution step yielded better results than without it and this step is therefore necessary for improving the reproducibility of the method. No significant differences were encountered between the standard isolation method and that used in the authors' laboratories. The results of this study indicate that milk powder is suitable as basic material for reference samples and that a reconstitution step should be included in the standard salmonella isolation procedure.

Animals↗
PubMed1985

[Possibilities for salmonellosis control].

With special regard to the situation in the Federal Republic of Germany, the potential of prevention and control of Salmonellosis is evaluated on the basis of recommendations made by experts of WHO. This is done by a comparison of measures already carried out and methods still in the stage of experiment or discussion, based on 3 main points, and taking in account their usefulness: Eradication of Salmonella infections in animals; decontamination of raw foods; observation of hygienic principles for handling and preparation of foods for human consumption.

Animal Feed↗
PubMed1980

Laboratory induced variations in a standardized Salmonella isolation method.

Four microbiologists from four European laboratories came together to a single laboratory for two weeks and during that period examined 100 samples of minced meat artificially contaminated with salmonellae and 100 naturally contaminated samples using a standardized technique. No significant differences were found between the results obtained by the different analysts with 92 to 97 of the artificially contaminated and 30 to 42 of the naturally contaminated samples being found positive. Over a further period of eight weeks, these analysts examined the same number of samples in their own laboratories again using an identical procedure. There were no significant containing approximately 100 salmonellae per gram but significant differences (43 to 93) were found in isolation rates from the artificially contaminated samples copntaining approximately 1 salmonella per gram. The differences in findings between the first and the second part of the experiments may have been caused fairly by variations in media preparation, temperature of incubators, storage conditions of media and thawing conditions of samples etc., and secondly by differences in working conditions such as performing only one task during two weeks in contrast to examining the samples as part of the daily routine. At high levels of contamination, these factors do not appear to have an important influence on the performance of a laboratory.

Animals↗
PubMed1978

Comparative studies on the isolation of salmonella from minced meat.

Comparative studies carried out in four laboratories revealed that in the examination of frozen or fresh minced meat samples tryptone soya broth and glucose mineral salts medium used for pre-enrichment gave the same results as buffered peptone water. The three tetrathionate media (Cardiff formula, Difco and Oxoid) used for enrichment after pre-enrichment, yielded approximately the same number of positive samples and about the same number of frozen and cooled samples was found positive when data of all four laboratories were considered. Between laboratories a considerable variation in results was found. This indicates the necessity to conduct comparative trials in more than one laboratory to validate the use of a specific method for regulatory purposes.

Bacteriological Techniques↗
PubMed1977

[Phage-typing and tetracycline resistance in Salmonella panama strains of animal origin in the Federal Republic of Germany (1969-1975) (author's transl)].

505 out of 1369 S. panama strains isolated mainly from animals, foods, and feedstuffs from 1969 to 1975 were phage-typed. 41% (= 207) of the S. panama isolates examined originated from swine, 26% from cattle and calves, 15% from dogs, and 13% were from other animal species and materials. 465 strains (=92%) showed typical reactions. 23% were specified as phage-type A, 24% as phage-type B and 36% as phage-type G. Phage-types D, E, and F did not occur. In swine, being the most frequent carriers of S. panama, phage-types A, B, and G had nearly the same shares. In dogs, phage-type G predominated to which nearly one half of the examined S. panama isolates from this species belonged. 205 (=41%) out of 505 strains examined for their resistance to antibiotics proved to be tetracycline-resistant. All 123 strains of phage-type B were tetracycline-resistant, all 35 strains of phage-type C were tetracycline-sensitive. 5 strains of phage-type A exhibited transferable tetracycline-resistance determinants.

Animals↗
PubMed1975

[Comparative studies of methods of salmonella enrichment (author's transl)].

Eight different methods of salmonella enrichment were compared in two series of experiments involving 100 samples of whole-egg powder and 80 samples of frozen whole liquid egg, respectively. 66 out of a total of 100 samples of whole-egg powder had been artificially infected with varying numbers of S. typhi-murium; 60 out of 80 samples of frozen whole liquid egg were found to be naturally infected with various salmonella species. 3 of the 8 methods (Table 1) were compared within an international collaborative study with 14 laboratories in 11 countries participating. A reduction of the pre-enrichment period from 18 to 6 hours and of volumes used in pre-enrichment and selective enrichment from 10 and 100 ml, respectively to 1 and 10 ml, respectively were found to have adverse influence upon the result of isolations, in particular in the case of weakly infected samples. In contrast, extended incubation over 48 hours as well as preparation of two sub-cultures on solid selective media following incubation of enrichment cultures over 18-24 hours and 42-48 hours, respectively always resulted in a certain increase of salmonella yield which, however, exhibited gradual differences for the individual methods examined. Preparation of a 2nd sub-culture meant, in particular, a decisive improvement of the result of isolations from artificially infected samples if selenite-cystine enrichment volumes were 10 and 100 ml, respectively. The best results could be obtained by means of the following methods of enrichment: Pre-enrichment of material in buffered peptone water at 37 degrees C over 18 hours; pipetting of 10 ml inoculated and incubated pre-enriched material into 100 ml selenite-cystine or tetrathionate enrichment medium according to MULLER-KAUFFMANN; onward incubation of the enrichment culture at 43 degrees C over 48 hours; and preparation of sub-cultures on solid selective media after 24 and 48 hours. The method using tetrathionate enrichment medium was found to be most expensive, results, however, were the most consistent ones.

Bacteriological Techniques↗
PubMed1975

[Nine new Salmonella species belonging to sub-genera I, II, and III and a new serological variant of S. tornow (author's transl)].

Between October 1971 and March 1972, 168 samples were collected from tank-water and faeces of amphibious animals and reptiles living in the Aquarium of the Berlin Zoo. They were examined for Salmonella and Arizona. Nine unknown Salmonella species and one new serological variant of S. tornow were isolated. Two of the new species were found to belong to sub-genus I, three to sub-genus II, and for to sub-genus III (Arizona) (see article).

Amphibians↗