Abstract
BACKGROUND AND AIM: Antimicrobial resistance (AMR) in extended-spectrum β-lactamase (ESBL)-producing Klebsiella pneumoniae is a growing global public health concern, especially at the human-animal-environment interface of dairy farming systems. Dairy farms may serve as reservoirs for resistant bacteria through contaminated milk, feed, water, soil, and human-related environmental sources, enabling transmission within a One Health framework. This study aimed to determine the prevalence of AMR, multidrug resistance (MDR), and ESBL-producing K. pneumoniae across various matrixes in dairy cattle farms in Batu City, East Java, Indonesia, to identify potential on-farm reservoirs and transmission pathways. MATERIALS AND METHODS: A cross-sectional surveillance study was conducted from May to August 2025 on 59 dairy farms. One sample per matrix per farm was collected, including milk, forage, soil, animal drinking water, hand-wash water, and feces (total n = 354). Isolation and phenotypic identification of K. pneumoniae were carried out using standard microbiological and biochemical methods. Antimicrobial susceptibility testing against seven antibiotics representing different classes was performed using the Kirby-Bauer disk diffusion method following Clinical and Laboratory Standards Institute guidelines. Isolates resistant to ≥3 antimicrobial classes were classified as MDR, and ESBL production was confirmed using the double-disk synergy test. Prevalence estimates were calculated with 95% confidence intervals. RESULTS: K. pneumoniae was found in 61.3% (217/354) of all samples, with the highest occurrence in forage feed (84.7%), drinking water (74.6%), hand-wash water (71.2%), and soil (71.2%), followed by milk (50.8%) and feces (15.3%). High resistance rates were seen for ampicillin (89.4%), streptomycin (71.4%), and cefotaxime (38.3%), while resistance to ciprofloxacin was low (2.8%). MDR was present in 35.0% (76/217) of isolates, most commonly showing resistance to three antimicrobial classes (61.8%). Among the MDR isolates, 21.1% (16/76) were confirmed as ESBL producers, mainly from environmental sources, especially forage feed and drinking water. CONCLUSION: The widespread detection of MDR and ESBL-producing K. pneumoniae in animal-derived, environmental, and human-related samples shows that dairy farms serve as significant One Health reservoirs of antimicrobial resistance. Environmental factors, particularly feed and water, seem to play a crucial role in the persistence and spread of resistance. These results provide baseline epidemiological data for Indonesian dairy farms and emphasize the importance of better antimicrobial stewardship, improved farm biosecurity, and future molecular surveillance to better understand resistance patterns and support risk-based strategies to reduce AMR dissemination in dairy production ecosystems.