THE BASIC BIOLOGICAL PROPERTIES AND ANTIBIOTIC RESISTANCE OF ISOLATESOF STREPTOCOCCUS AGALACTIAE ISOLATED FROM COW MILK IN KOSTANAY REGION

Abstract

One of the most common causative agents of bovine mastitis is Str. agalactiae, which is also potentially dangerous for humans and aquatic animals. To date, there is a trend towards the emergence and spread of Str. agalactiae microorganisms with multidrug resistance. The constant use of antimicrobial drugs contributes to the emergence of polyresistant microorganisms, which shows the relevance of rational pharmacotherapy of animals.

The article presents the results of studying the main phenotypic properties of Str. agalactiae isolated from the milk of cows with clinical and subclinical forms of mastitis. For the studies conducted during 2021-2023, 398 milk samples were collected, 26 isolates of Str. agalactiae (6.5%) were isolated and identified.

Studies on antibiotic sensitivity were carried out using the disco-diffuse method. The studies results showed that, the largest number of isolates were resistant to the group of beta–lactam antibiotics: benzylpenicillin (76.9%), amoxacillin (65.3%), ampicillin (65.3%); aminoglycosides – kanamycin (61.5%) and macrolides – tylosin (50.0%), less resistant to tetracyclines: doxycycline (42.3%) tetracycline (30.7%). The studied strains of Str. agalactiae demonstrated the lowest resistance to levomycetin – 23.0%.

Strains of Str. agalactiae in our studies showed resistance to all antibacterial drugs to different extents. This indicates the urgency of the problem of antibiotic resistance in Kostanay region and the need to find solutions.