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Research Article | 04 Jul 2026

Occurrence and multidrug resistance patterns of Escherichia coli isolated from raw goat milk with subclinical mastitis in Banyuwangi, Indonesia

Ratih Novita Praja1,2 ORCID , Aditya Yudhana1,2 ORCID , Amung Logam Saputro1 ORCID , Jonathan Mark Hamonangan3 ORCID , Azhar Burhanuddin1 ORCID , Sarasati Windria4 ORCID , Asmaa Mostofa Elbastawesy5 ORCID , Hanisha Mehta3 ORCID , and Shifa Salsabilla Praja1 ORCID Show more
INTERNATIONAL JOURNAL OF ONE HEALTH | Article No. 5 | pg no. 233-244 | Vol. 12, Issue 2 | DOI: 10.14202/IJOH.2026.233-244
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ABSTRACT

                      
Background and Aim: Antimicrobial resistance (AMR) has emerged as a major threat to animal and public health. Escherichia coli is an important foodborne pathogen and a causative agent of subclinical mastitis in dairy animals. In Siliragung Subdistrict, Banyuwangi, Indonesia, fresh goat milk is commonly consumed, creating potential risks for the transmission of resistant bacteria. This study investigated the occurrence and AMR patterns of E. coli isolated from raw goat milk obtained from goats with subclinical mastitis. 
Materials and Methods: A cross-sectional study was conducted between June and December 2024 involving 224 lactating goats from seven dairy goat farms in Siliragung Subdistrict, Banyuwangi, Indonesia. Subclinical mastitis was screened using the California Mastitis Test, and samples with scores of 3 and 4 were subjected to bacteriological examination. Presumptive E. coli isolates were identified using colony morphology, Gram staining, and indole, methyl red, Voges–Proskauer, and citrate biochemical tests. Antimicrobial susceptibility was evaluated by the Kirby–Bauer disk diffusion method against ampicillin, cephalothin, streptomycin, ciprofloxacin, erythromycin, chloramphenicol, trimethoprim, and tetracycline according to Clinical and Laboratory Standards Institute (CLSI) guidelines. Multidrug resistance (MDR) was defined as resistance to at least three antimicrobial classes. 
Results: Among 224 raw goat milk samples, 91 (40.6%) were positive for subclinical mastitis. Thirty isolates (32.9%) were identified as E. coli. The highest resistance rates were observed for erythromycin (63.3%) and tetracycline (53.3%), whereas the highest susceptibilities were recorded for ciprofloxacin (76.7%) and trimethoprim (60.0%). Ten isolates (33.3%) exhibited MDR. Marked variation in MDR prevalence was observed among farms, ranging from 0% to 50%. 
Conclusion: Raw goat milk from goats with subclinical mastitis in Banyuwangi harbored antimicrobial-resistant and multidrug-resistant E. coli. The predominance of erythromycin- and tetracycline-resistant bacteria and the substantial MDR rate emphasize the need for prudent antimicrobial use, improved farm biosecurity, routine susceptibility testing, and integrated One Health surveillance to reduce the risk of dissemination of resistant bacteria through the dairy goat production system. 
                      
Keywords: antimicrobial resistance, Banyuwangi, dairy goats, Escherichia coli, multidrug resistance, public health, raw milk, subclinical mastitis, zoonotic risk.