Listeria monocytogenes is ubiquitous bacteria. It causes listeriosis, a serious infectious disease which occurs as consequence of consumption of food contaminated with this pathogen bacterium. The frequency of incidence of listeriosis is low (1%), but with high mortality rate (30%). In certain countries (USA and Switzerland) large outbreaks of listeriosis were associated with consumption of fresh cheeses and milk. Studies on presence of L.monocytogenes in raw milk, carried out in Europe, have shown that 2,5-6% of samples can be contaminated with L.monocytogenes. In the process of production of milk and dairy products, it most commonly occurs as consequence of post-pasteurization contamination. L.monocytogenes has the ability to multiply and grow at low temperatures (4 0 C) and to survive even on freezing temperatures, and as such poses risk for health of consumers, if found in milk, cheese, ice-cream and other dairy products. In order to prevent the contamination of product with this bacterium, producers much implement prevention measures, and special attention must be focused on critical points in the production process and adequate sanitation. The general characteristics of L.monocytogenes, are presented in the study, also its resistance to environment, some listeriosis outbreaks, its presence in milk and dairy products and major hygiene measures.

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Abstract:The penicillin is a broad-spectrum antibiotic, active against a large number of Gram-positive and Gram-negative microorganisms.

In the stability test of the mastitis reagent ad us.vet., as the finished product, three production series were tested in quantities of 500 ml of the sample, under appropriate storage conditions. For the testing, the appropriate uniformity of temperature and relative humidity was provided. Also, the procedure of the stability test was determined, which included the initial state, then every three months until the end of the first trial and a final testing at the end of shelf life (0, 3, 6, 9, 12 and 18 months). Of the tested parameters the following were included: appearance, pH value of the solution, dry residue (in %) and microbiological purity. [Projekat Ministarstva nauke Republike Srbije, br. 46009 i br. 31034]

The paper examines the excretion of oxitetracycline residue in milk of East Friesian cows that received a single intrauterine treatment. A total of 10 cows were divided into two equal experimental groups, and one group was administered a dose of 0.5 g/cow, and the other group 1 g/cow oxitetracycline. Oxitetracycline residue in milk was determined using the Rezazurin test method with Str. Thermophilus, as the test microorganism. Following the i.u. administration of oxitetracycline in a dose of 0.5 g/cow the average duration of the presence of its residue in milk in treated cows was 46.0 (34-58) hours, with oxitetracycline residue concentration ranging from 0.1-1.4 mcg/ml milk. After the dose of 1 g/cow, this time period was 55.6 (34-82) hours, and the oxitetracycline residue concentration ranged from 0.1-2.2 mcg/ml milk