BIODIVERSITAS ISSN: 1412-033X Volume 23, Number 10, October 2022 E-ISSN: 2085-4722 Pages: 5050-5055 DOI: 10.13057/biodiv/d231011 Prevalence and antimicrobial resistance in Streptococcus agalactiae isolated from raw milk in Pasuruan and Lumajang districts, East Java, Indonesia DIAN AYU PERMATASARI 1 , FAUZIAH ANGGRAENI 2 , BUDIARTO 1 , DEWA KETUT MELES 3 , IWAN SAHRIAL HAMID 3 , YULIANA PUSPITASARI 4 , MUSTOFA HELMI EFFENDI 1, , ASWIN RAFIF KHAIRULLAH 5 , DHANDY KOESOEMO WARDHANA 1 , EMMANUEL NNABUIKE UGBO 6 1 Division of Veterinary Public Health, Faculty of Veterinary Medicine, Universitas Airlangga. Jl. Dr. Ir. H. Soekarno, Kampus C Mulyorejo, Surabaya 60115, East Java, Indonesia. Tel./Fax.: +62-31-5992785,  email: mheffendi@yahoo.com 2 Student of Faculty of Veterinary Medicine, Universitas Airlangga. Jl. Dr. Ir. H. Soekarno, Kampus C Mulyorejo, Surabaya 60115, East Java, Indonesia 3 Division of Veterinary Pharmacology, Faculty of Veterinary Medicine, Universitas Airlangga. Jl. Dr. Ir. H. Soekarno, Kampus C Mulyorejo, Surabaya 60115, East Java, Indonesia 4 Division of Veterinary Microbiology, Faculty of Veterinary Medicine, Universitas Airlangga. Jl. Dr. Ir. H. Soekarno, Kampus C Mulyorejo, Surabaya 60115, East Java, Indonesia 5 Doctoral Program in Veterinary Science, Faculty of Veterinary Medicine, Universitas Airlangga. Jl. Dr. Ir. H. Soekarno, Kampus C Mulyorejo, Surabaya 60115, East Java, Indonesia 6 Department of Applied Microbiology, Faculty of Science, Ebonyi State University, Abakaliki, Nigeria Manuscript received: 20 August 2022. Revision accepted: 27 September 2022. Abstract. Permatasari DA, Anggraeni F, Budiarto, Meles DK, Hamid IS, Puspitasari Y, Effendi MH, Khairullah AR, Wardhana DK, Ugbo EN. 2022. Prevalence and antimicrobial resistance in Streptococcus agalactiae isolated from raw milk in Pasuruan and Lumajang districts, East Java, Indonesia. Biodiversitas 23: 5050-5055. Milk and dairy products are nutritionally important in the diet worldwide. The microbiological quality of raw milk is essential for the quality of the final dairy product. The presence of Streptococcus agalactiae is frequently associated with high somatic cell counts in milk and decreased milk yield. Streptococcus agalactiae infections have major consequences for public health. This study aimed to identify the prevalence and antimicrobial resistance of Streptococcus agalactiae isolated from raw milk in Pasuruan and Lumajang, East Java, Indonesia. Raw milk samples were collected from three sub-districts in Pasuruan (Tutur, Grati and Purwosari) and three sub-districts in Lumajang (Senduro, Karangbendo, and Tekung). California mastitis test (CMT) was performed to confirm the presence of somatic cells, S. agalactiae was identified using standard microbiological methods, and antibiotic resistance was determined by Kirby-Bauer disc diffusion method using Mueller-Hinton agar. Results showed that 89 (79.46%) out of 112 dairy cows were positive for CMT, which indicated the presence of mastitis. Bacteria isolation was performed on CMT-positive samples and four samples were showed the presence of S. agalactiae (4.49%). Based on the sensitivity test against various antibiotics, it was observed that S. agalactiae isolates were resistant to ampicillin (75%), and erythromycin (50%), and were sensitive to cefotaxime (100%), tetracycline (75%), and chloramphenicol (100%). This research reported that Streptococcus agalactiae organism is one bacterium that is implicated in mastitis infections. Therefore, monitoring the antibiotic susceptibility profiles of this organism is needed in veterinary medicine, in order to make an appropriate choice of drug for treatment, improve high cure rates and minimize the increase of drug resistance. Keywords: Antimicrobial resistance, California Mastitis Test, public health, raw milk, Streptococcus agalactiae INTRODUCTION Important nutrients in diets around the world are largely supported by milk and dairy products. The microbiological quality of raw milk is very important for the quality of the final milk product (Åkerstedt 2012). Cases of mastitis in dairy cows often use antimicrobial drugs, where mastitis is one of the most common infectious diseases in dairy cows. The bacteria involved in bovine mastitis are classified as infectious or environmental pathogens based on their epidemiological relationship to the disease. Streptococcal species are the main mastitis pathogens, along with Staphylococcus aureus and coliforms. Streptococcus agalactiae is associated with cattle and is well adapted to the mammary glands (Minst et al. 2012). Therefore, it is the only mastitis pathogen that can be removed from the herd using blanket therapy with penicillin or its derivatives (Boonyayatra 2020). Subclinical mastitis is difficult to detect visually. The signs are inflammation of the udder and abnormal milk. Finding new mastitis markers that can identify the condition at an early stage is critical for milk production (Pongthaisong et al. 2016). Generally, increasing the number of milk somatic cells and bacterial culture are the methods used to detect subclinical mastitis (Radostits et al. 2007). An increase in the number of somatic cells in milk in cases of mastitis is a common and expensive disease in dairy cows that shows varying degrees of severity and reduces the quantity and quality of milk produced (Heikkilä et al. 2012; Rollin et al. 2015). Streptococcus agalactiae, a member of the Lancefield B group, is an important cause of chronic infectious bovine mastitis (Herlina et al. 2015). It