Робота виконана на кафедрі мікробіології та імунології Навчально-наукового центру «Інститут біології та медицини» Київського національного університету імені Тараса Шевченка та в науково-дослідному департаменті ТОВ «Центр Ветеринарної Діагностики» Біотехнологічний процес харчової промисловості прагне забезпечити ринок якісними та цінними харчовими продуктами, що можуть бути отримані тільки з використанням молока високої якості. Заходи, що забезпечують належну якість молока: підтримка здоров’я молочної залози шляхом постійної профілактики хвороби вимені, визначення і виключення мікробіологічних та хімічних джерел забруднення. У дисертаційній роботі проаналізовано знання про механізми патогенезу та розвитку маститу. Виникнення нових штамів бактерій з мультирезистентністю до антибіотиків сприяє пошуку нових ефективних терапевтичних засобів для лікування. Отже, контроль збудників є обов’язковою умовою для профілактики та лікування маститу. Проведена оцінка розповсюдження бактеріальних ізолятів на фермах України дозволяє стверджувати, що поширення патогенних збудників зростає та потребує розв’язання актуальної проблеми. Запропоновано удосконалені біотехнологічні схеми діагностики контагіозного маститу у корів на фермах. Mastitis (inflammation of the mammary gland) in dairy cattle is a multifactorial disease, which still is a main cause of economic problems in the developed countries. The knowledge about the mechanisms of pathogenesis and development of mastitis is gradually expanding, and emergence of new multiresistant to antibiotics bacterial strains encourages the search for new effective therapeutic options for treatment. So, the control of the pathogens is a mandatory condition for the prevention and treatment of mastitis. Biotechnological process of the food industry craves to provide the market with quality and valuable food that can only be obtained by using high-quality milk.As for the milk quality, it is influenced by the following indicators: the number of somatic cells, the absence of pathogenic bacteria and inhibitors (residues of veterinary drugs, antibiotics, hormones, etc.), exogenous contamination. There are measures to ensure proper milk quality, such as: maintaining breast health by constantly preventing udder disease, identifying and eliminating microbiological and chemical sources of contamination. Many countries around the world are now paying close attention to the study of udder disease, its etiology and prevention. In this regard, the search for new measures to increase milk productivity and improve milk quality is relevant and has scientific and practical significance. The thesis is devoted to the identification of bacterial isolates taken from Ukrainian milk cows. The author analyzed the antibiotic sensitivity and antibiotic resistance of bacteria. For the first time in Ukraine, the use of lactate dehydrogenase for the initial detection of early subclinical infection has been proposed. The assessment of the spreading of bacterial isolates on farms in Ukraine suggests that the prevalence of pathogens is growing and this issue needs to be addressed. The study has shown that in case of subclinical infection of mammary gland 100 % of selected isolates are contagious mastitis pathogens. However, due to analyzed mastitis samples (clinical and subclinical forms) from different farms of Ukraine, it was found that 15 % of samples were positive for Staphylococcus aureus and 26 % of samples – for Streptococcus agalactiae, 59 % of samples contained non-contagious pathogens of mastitis. In addition, it is shown that most isolates of bacteria that cause mastitis are sensitive to amoxicillin + clavulanic acid and gentamicin – 93.5% of all samples. Contagious mastitis pathogens susceptible to Amoxicillin, Amoxicillin + Clavulanic acid, Gentamicin, Ampicillin, Lincomycin, Cloxacillin, Rifampicin, Bacitracin, Rifampicin, and Trimethoprim; resistant to Tylosin and Streptomycin. It is also illustrated that Streptococcusag agalactiae, Candida spp, Aspergilus spp have a 100 % effect compared to Escherichia coli 75 %, Staphylococcus aureus 70 % bactericidal effect after milking cows. The obtained data shows that for optimal results it is necessary to check the sensitivity of disinfectants before use. Having tested 20 samples of milk for the presence of genetic material Mycoplasma bovis was found in 10 of them which is a reason to talk about the spread of this disease in the country. The research findings illustrated that 2 out of 20 milk samples have low levels of the activity of the enzyme lactate dehydrogenase (LDH) and somatic cells of the level was 250,000 in 1 ml. and negative bacteriological test results, which may indicate the absence infection of mammary gland and physiological increase in the amount of SC in secretion. With increased activity of the LDH enzyme and the level of SC, which does not exceed 250,000 in 1 ml, in every single case either bacteria Streptococcus agalactiae or Staphylococcus aureus was isolated, indicating monoinfection. At the level of SC from 250,000 to 500,000 in 1 ml (4 out of 20 milk samples) both bacteria Streptococcus agalactiae and Staphylococcus aureus were isolated, which indicated a mixed infection. Using the flow cytometry, the following indicators were detected: Precipitate of SC necrotic cells in cows without mastitis are 24 % compared with 67 % in cows with mastitis. The number of apoptotic SC in cows without mastitis is 33 % compared with 12 % in cows with mastitis. As a result, we conclude that apoptosis is closely related to the function of neutrophils and macrophages and plays a key role in protecting against pathogens and the physiology of the inflammatory response. The novelty of the work is as follows for the first time, a scientific approach to monitoring udder health status of cows for subclinical inflammation has been improved. It is established that as a result of control of contagious pathogens on the farm the quality of cow's milk will improve. A determination of the enzyme lactate dehydrogenase as biomarkers of inflammation of the udder and reasonably complex combination of biological research methods for the determination of infectious agents in secret udder of cows. The genetic material of Mycoplasma bovis DNA was found on 10 farms of Ukraine from Mykolayiv, Poltava, Kharkiv, Kyiv regions, which gives grounds to draw a conclusion about the prevalence of the pathogen on the territory of Ukraine. it is possible to observe subclinical infection of the mammary gland of cows. Thus, as a result of a complex combination of biological research methods, a scientific approach to monitoring udder health status for the presence of subclinical inflammation on the farm is justified, which will help to qualitatively perform microbiological analysis of milk by dividing samples into groups. And in the group of animals. In order to identify contagious pathogens and provide an early diagnosis of subclinical mastitis, a scientific approach to diagnosis on farms in Ukraine has been proposed and developed.