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F M van Leusden

Publications and source records attributed to F M van Leusden.

31 records · Page 2Linked to original sources
PubMed1979

[Epidemiological studies on Salmonella in a particular area ('Walcheren Project'). IV. The incidence of Salmonella in the sewage system, in faeces of man and pets as well as in shops, kitchens and lavatories in the village of Aagtekerke (author's transl)].

As part of the epidemiological investigations on Salmonella on the island of Walcheren, the contamination of sewage water in the village of Aagtekerke was studied over a prolonged period. These studies showed that this sewage water was frequently contaminated by large numbers of Salmonella. In the present study, efforts were made to find an answer to the question of the origins of this contamination. For this purpose, the incidence of Salmonella in the sewage system, in faeces of man and pets as well as in shops, kitchens and lavatories in the village of Aagtekerke was studied for a period of three weeks in June 1977. In addition to the findings in the sewage system (including the inlet water and effluents of the sewage works) which were positive for Salmonella, this organism was only isolated from a few faecal samples of human and animal origin. Serotyping showed that the strains isolated from human faeces were similar to those found to be present in the sewage system. This fact, in conjunction with the results of the bacterial counts. suggests that the sewage system was only contaminated by the small number of carriers. The reduction of contamination observed in the sewage system during the period of investigation could be evidence of the fact that Salmonella organisms cannot survive by themselves in an environment of this type, at least not at the temperatures recorded on collecting samples from the sewage water. Growth of organisms under more favourable conditions cannot be ruled out. An inquiry on dietary habits and kitchen hygiene of the local population showed that contamination within households. Origination with the food, is a real possibility.

Adult↗
PubMed1978

[Studies on the possibility of producing broilers free from Salmonella (author's transl)].

The results of the present study show that the only method by which broilers could be reared free from Salmonella would be to adopt a number of radical measures at the same time. These measures include the production of Salmonella-free one-day chicks, decontaminating the feed, thorough cleansing and decontamination of the houses and preventing the introduction of Salmonella from the environment. Adopting separate measures was found to have a very slight effect.

Animal Feed↗
PubMed1978

Epidemiological studies on salmonella in a certain area ("Walcheren project") III. The presence of salmonella in man, insects, seagulls and in foods, chopping-block scrapings from butcher's shops, effluent of sewage treatment plants and drains of butcher's shops.

For a period of three months in a relatively small area (Walcheren), various materials (meat and meat products, insects, seagull droppings, chopping-block scrapings from butcher's shops, effluent of sewage treatment plants, drains from butcher's shops and stools of patients) were examined again for the presence of Salmonella as a continuation of previous investigations. As had been the case in previous studies, S. typhimurium (27.5%), S. panama (22.2%) and S. brandenburg (9.2%) were the three most frequently isolated serotypes. The three most frequently isolated phage types of S. typhimurium were II 505 (62.1%) II 502 (5.3%) and I 650 (4.2%). The serotypes and phage types were present in almost all the materials examined which again emphasizes the fact that there are contamination cycles of Salmonella. These studies show that the route of contamination divides in the butcher's shops. Salmonella organisms carried with the meat from the slaughter-house find their way into the drains on the one hand, and through meat and meat products, to the consumer on the other. Moreover, the high degree of contamination of effluent is not in accordance with the small number of cases of salmonellosis in man.

Animals↗
PubMed1977

Survival of Salmonella eastbourne and Salmonella typhimurium in milk chocolate prepared with artificially contaminated milk powder.

Milk chocolate mass containing salmonellas was prepared by mixing artificially contaminated milk powder with the other ingredients at a temperature of about 40 degrees C. From this mass bars were made. Two series were prepared, with S. eastbourne and S. typhimurium respectively. The number of surviving salmonellas was counted after various periods of storage, up to 19 months. S. eastbourne was reduced in numbers during 19 months from an initial count of ca. 3 x 10(4) to ca. 3 x 10(2) per 100 g of chocolate. S. typhimurium died off more rapidly, and was not detectable in about 55 g after 15 months, in spite of an initial count of ca. 10(5) per 100 g.In these experiments the salmonellas in the milk powder had had to survive the spraying procedure and the adverse conditions in the dried powder. This may be the reason why S. eastbourne showed a distinctly better survival on storage than the same serotype showed in previous experiments in which the organism was added as a broth culture to the chocolate mix. With S. typhimurium, however, such a difference was hardly detectable.Possible explanations of these results are discussed.

Animals↗
PubMed1976

Survival of Salmonella east bourne and Salmonella typhimurium in chocolate.

Experiments were carried out to assess the reduction rate of two salmonella strains (S. eastbourne and S. typhimurium) in chocolate bars. After artificial contamination of chocolate, after 'conching', with about 10(6) S. eastbourne/g. this organism was still recovered after 9 months storage. The strain of S. typhimurium was less resistant. Both serotypes died off more rapidly in bitter chocolate than in milk chocolate. After contamination with a smaller dose (about 10(3)/g.) with these two serotypes, similar differences were observed.

Cacao↗
PubMed1975

[Quantitative studies for the presence of Salmonellae in deep frozen broiler chickens (author's transl)].

When poultry carcasses were examined immediately prior to deep freezing those which were contaminated with salmonellae were generally found to contain about 17/100 g skin. In two instances more than 1400 salmonellae/100 g skin were found to be present. After deep freezing and thawing a 5 fold reduction had occurred in the numbers of salmonellae present. A high positive correlation was found between the number of Salmonella organisms on the skin and that in the thaw water.

Animals↗
PubMed1975

Comparison of several methods for the isolation of salmonellae from egg products.

Lactose broth and buffered peptone water proved to be equally effective as preenrichment media in the isolation of salmonellae from egg products. With tetrathionate bile brilliant green broth, incubated at 43 degrees C as enrichment medium, more samples were found to be positive than with selenite cystine broth incubated at 37 degrees C or 43 degreesC and selenite brilliant green broth incubated at 37 degrees C. As selective agar, brilliant green agar proved to be more reliable than bismuth sulfite agar. These results indicate that the ISO method for the isolation of salmonellae from meat and meat products can be successfully used for the examination of egg products.

Agar↗
PubMed1975

Further studies on the isolation of injured Salmonellae from foods.

Two series of experiments with artificially contaminated milk powder were carried out. In the first series the influence of storage on the minimal resuscitation time was studied. In the second series the influence of ox bile versus taurocholate as inhibitive substances in tetrathionate bile brilliant green broth was studied. The results clearly indicate that in a given population cells may be present which are injured to various degrees, and that studies to determine minimal resuscitation times may be complicated by this fact.

Animals↗
PubMedDate not supplied

Immunoblotting technique for the detection of allergens of Aspergillus fumigatus: influence of Nonidet P-40 on the sensitivity.

Immunoblotting provides a useful technique for the study of antigens, antibodies and allergens. To overcome problems regarding the loss of antigenic properties during the blotting and developing procedures, several solutions have been described. The inclusion of Nonidet P-40, recommended to increase the sensitivity of developing procedures for immunoblots, in an existing procedure for the detection of allergens of Aspergillus fumigatus, however, led to decreased sensitivity of the method.

Allergens↗