Microbiological and electrophoretic studies of the binding of antibiotics by milk and milk components
Authors:   , Khan Nadir 
Published: June 2024

"The most common form of mastitis is associated with the growth and multiplication of bacteria in the milk secreting tissues of the udder. The infected gland reacts to microbial invasion and the host defense mechanism may overcome infection. If this fails, the susceptibility of the host and the virulence of the causative agent will determine the severity of ensuing mastitis. The presence of the pathogen in the gland and the host's reaction make the development of mastitis a very dynamic process. The strategy for the control of mastitis consists of three components; namely, immunization, sanitary herd management practices and chemotherapy. A control program, therefore, should take into consideration those factors which will reduce new infections and eliminate established infections to levels that will reduce the incidence of disease. Immunization has not shown great promise; therefore, sanitation and chemotherapy are the most effective means available. In the last fifteen years, with the introduction of several antibiotics for mastitis treatment, there has been a definite shift in the causative organism, and staphylococcal mastitis has become more common. Another interesting aspect which has emerged in the last few years is the fact that the higher incidence of staphylococcal mastitis is not due to higher rates of infection by these microorganisms but to the longer duration of these infections. The only way this long duration of infection can be shortened is by effective antibiotic therapy. Most chemotherapeutic preparations are introduced into the udder as infusions. In the development of these intramammary preparations it is important to consider the mode of action of these antibiotics (bacteriostatic or bactericidal); their range of activity against the pathogens involved; the minimal concentration required in the udder; and the ability of microorganisms to develop resistance. In contemporary human chemotherapy, it is taken for granted as necessary to measure the extent of serum binding of drugs under investigation. Milk, like serum, contains several biologically important proteins. Also, pronounced changes in milk composition are associated with bovine mastitis. Several investigators have reported considerable increases in blood serum albumin in mastitic milk. In some cases when mastitis-causing isolates were subjected to sensitivity testing, they were sensitive to concentrations of antibiotics much lower than expected on the basis of antibiotic treatment. Several investigators have also reported that, in in vitro tests, more antibiotic is required to obtain the same degree of inhibition in the presence of milk than in nutrient broth. It is possible for therapeutic failure to result from the fact that sensitivity information is obtained by tests conducted on laboratory media. These procedures and practices do not simulate the conditions which exist in an inflamed gland. The present study was undertaken to investigate the effects of casein, normal milk, abnormal milk, and normal milk plus bovine serum albumin on the activity of chlortetracycline, oxytetracycline, tetracycline, neomycin, erythromycin and lysostaphin. These effects were studied by microbiological and electrophoretic assay methods."--Introduction.