Outbreaks of food-borne listeriosis have often involved strains of serotype 4b. Examination of multiple isolates from three different outbreaks revealed that ca. 11 to 29% of each epidemic population consisted of strains which were negative with the serotype-specific monoclonal antibody c74.22, lacked galactose from the teichoic acid of the cell wall, and were resistant to the serotype 4b-specific phage 2671.
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Indigenous yeasts can be detected at high populations in raw milk Cantal cheese, a French Protected Denomination of Origin (PDO) hard cheese. To investigate their use as adjunct cultures to promote flavour development in Cantalet (small Cantal) cheese, three strains isolated from raw milk Cantal cheese, Kluyveromyces lactis, Yarrowia lipolytica, and Pichia fermentans were added at 3 (E3) and 5 (E5) log(10) colony-forming units (cfu)/mL to microfiltered milk at a ratio of 80/10/10 viable cells, respectively. The global microbial, compositional and biochemical changes induced by the presence of yeasts in cheese were determined. Adjunct yeasts did not grow but stayed at viable populations of approximately 4 and 6 log(10) cfu/g in E3 and E5 cheeses, respectively, throughout the ripening period. They were mainly constituted of K. lactis, while P. fermentans and Y. lipolytica were not detectable after 3 and 45 days of ripening, respectively. Several species of indigenous yeasts were also detected in E3 cheeses at the beginning of ripening only, and in the control cheeses without yeasts added. Lactoccoci survived for longer periods in the presence of yeast adjuncts, while, conversely, the viability of Streptococcus thermophilus decreased more rapidly. The addition of yeasts did not influence cheese composition and total free amino acid content. In contrast, it slightly increased lipolysis in both E3 and E5 cheeses and markedly enhanced the formation of some volatile aroma compounds. The concentrations of ethanol, ethyl esters and some branched-chain alcohols were 6 to 10 fold higher in E5 cheeses than in the control cheeses, and only slightly higher in E3 cheeses. This study shows that K. lactis has a potential as cheese adjunct culture in Cantalet cheese and that, added at populations of 4-5 log(10) cfu/g cheese, it enhances the formation of flavour compounds.
In vivo colonization by different Lactobacillus strains on human intestinal mucosa of healthy volunteers was studied together with the effect of Lactobacillus administration on different groups of indigenous bacteria. A total of 19 test strains were administered in fermented oatmeal soup containing 5 x 10(6) CFU of each strain per ml by using a dose of 100 ml of soup per day for 10 days. Biopsies were taken from both the upper jejunum and the rectum 1 day before administration was started and 1 and 11 days after administration was terminated. The administration significantly increased the Lactobacillus counts on the jejunum mucosa, and high levels remained 11 days after administration was terminated. The levels of streptococci increased by 10- to 100-fold in two persons, and the levels of sulfite-reducing clostridia in the jejunum decreased by 10- to 100-fold in three of the volunteers 1 day after administration was terminated. In recta, the anaerobic bacterium counts and the gram-negative anaerobic bacterium counts decreased significantly by the end of administration. Furthermore, a decrease in the number of members of the Enterobacteriaceae by 1,000-fold was observed on the rectal mucosa of two persons. Randomly picked Lactobacillus isolates were identified phenotypically by API 50CH tests and genotypically by the plasmid profiles of strains and by restriction endonuclease analysis of chromosomal DNAs.(ABSTRACT TRUNCATED AT 250 WORDS)
In Denmark, porcine kidneys displaying macroscopic lesions of mycotoxic nephropathy are analysed for Ochratoxin A and the carcass condemned if the concentration exceeds 25 micrograms/kg. Since late 1982 these analyses have been conducted centrally. The reliability of the one-dimensional thin layer chromatographic method is discussed and results from an interlaboratory comparison are presented. From 1980 to 1984 there has been an overall decline in the rate of ochratoxicosis, interrupted in 1983 by a major increase geographically located in the northern half of Jutland. During that year 7639 kidneys were examined; 3% contained more than 150 micrograms/kg and 29% more than 25 micrograms/kg Ochratoxin A, corresponding to a condemnation rate of 15 per 100 000 slaughterings. The early stage of the increased incidence was characterized by kidneys with extremely high levels of the toxin; later most of the samples were negative or near-negative, as affected pigs were presumably fed a toxin-free diet before slaughtering. The efficacy of the control program is discussed in view of the 1983 data.
Of 85 strains of Bacillus cereus isolated in Norway from dairy products, 59% were found to be enterotoxigenic, and 15% were psychrotrophic. Six of the isolates (7%) were identified as potential psychrotrophic food-poisoning strains as they were both enterotoxigenic and exhibited good growth at 6 degrees C. Enterotoxin production was detected using the Western immunoblot technique, and a commercially available reversed passive latex agglutination (RPLA) assay (Unipath BCET-RPLA TD950). Both methods gave essentially the same results. In a separate study, the Western immunoblot and RPLA assays were used in a conjunction with the in vivo vascular permeability reaction (VPR) assay to determine enterotoxin production among 25 isolates of Bacillus cereus referred to the PHLS Food Hygiene Laboratory from incidents of diarrhoeal- and emetic-syndrome food poisoning and non-gastrointestinal infections. Eighty-four percent of these isolates were found to be enterotoxigenic by the Western immunoblot and the RPLA assays, and these results were in good agreement with those obtained by the VPR assay. In both studies, the BCET-RPLA kit proved to be a simple and reliable means for determining enterotoxin production by strains of Bacillus cereus.
The retrospective analysis of dysentery morbidity in Blagoveshchensk for the period of 1960-1987 was made. The regularities linking general natural and biological factors triggering the epidemic process with dysentery morbidity among the population are emphasized. The study revealed that under the conditions of Blagoveshchensk dairy products were of major epidemic importance among factors contributing to the transmission of dysentery. Such a factor as flies also had a definite influence on the epidemic process of dysentery. Another risk factor was drinking water which influenced the epidemic process both directly and indirectly through dairy products and, probably, other foodstuffs. Reliable correlation between dysentery morbidity among the population and the quality of dairy products, tap water and the number of flies was established.
The intestinal flora is considered to have an impact on the development of the immune system. In the anthroposophic lifestyle, a diet comprising vegetables spontaneously fermented by lactobacilli, and a restrictive use of antibiotics, anti-pyretics and vaccinations, is typical. The aim of this study was to assess the gut flora in infants in relation to certain lifestyle characteristics associated with anthroposophy. Sixty-nine children
The causes of the simultaneous rise of salmonellosis morbidity induced by S. enteritidis among the population of three towns in the Perm region were studied. The study revealed the leading role of eggs and chicken meat as factors contributing to the transfer of this infection to the population of different territories, commonly supplied with the products of one poultry plant. The contamination of eggs and chickens with S. enteritidis occurred at the plant due to Salmonella infection of chickens, parallel with the use of nonbalanced mixed fodder, originally intended for feeding swine. Analysis of the epidemic and epizootic processes of Salmonella infection in this epidemic situation made it possible to reliably establish the factors contributing to the transfer of the infective agent and the site of contamination.