Phenotypic Associations in Resistance to Medically Important Antibiotics Among Highly Resistant Bacteria Isolated from Cambodian Dairy Farms.
6 affiliations
- 1Cambodia Campus, Asian Satellite Campuses Institute, Nagoya University, Nagoya 464-8601, Japan.
- 2Faculty of Veterinary Medicine, Royal University of Agriculture, Phnom Penh 120501, Cambodia.
- 3Laboratory of Animal Production Science, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan.
- 4Department of Animal Health and Veterinary Public Health, General Directorate of Animal Health and Production, Phnom Penh 120603, Cambodia.
- 5Faculty of Veterinary Medicine, Chiang Mai University, Chiang Mai 50100, Thailand.
- 6Research Center of Producing and Development of Products and Innovations for Animal Health and Production, Chiang Mai University, Chiang Mai 50100, Thailand.
Abstract
Antimicrobial resistance (AMR) is recognized by global health authorities as one of the foremost public health and development challenges confronting humanity today, leading the WHO to establish categories of medically important antibiotics for humans and animals. On farms with a high burden of infection, inappropriate antibiotic use, mixed bacterial infections, and environmental contamination with antibiotics from animal sources might accelerate the development of antibiotic resistance, particularly from a One Health Approach. Therefore, this study was conducted to determine correlations in AMR among antibiotics using bacteria isolated from dairy farms with a high burden of intramammary infections. In addition, antibiotic resistance percentages were compared between a smallholder dairy farm and an intensive dairy farm in Cambodia, where the dairy industry has been established for only a few years. Bacterial isolates were collected from two dairy farms: Farm A, a medium-sized local farm with approximately 30 milking cows, and Farm B, a large intensive farm with approximately 480 milking purebred Holstein-Friesian milking cows. All bacteria were tested for antimicrobial susceptibility using a disk diffusion test with 17 antibiotics from nine classes. Classifications based on CLSI interpretive criteria were distinguished from those based on study-defined, extrapolated inhibition-zone thresholds, designated expected AMR (AMR-E). The latter classifications were exploratory and were not validated measures of resistance. The antimicrobials included antibiotics from classes important in human medicine: human-used only (HU), highest-priority critically important antimicrobials (HPCIA), critically important antimicrobials (CIAs), and highly important antimicrobials (HIAs). Fisher's exact test was used to compare AMR between farms (p < 0.05), and Spearman's correlation adjusted by a Benjamini-Hochberg (Q < 0.05) was used to evaluate associations among antimicrobial susceptibility classifications and between these classifications and multidrug resistance (MDR) status. The results showed that the distribution of bacteria differed between the two farms. For antibiotics used only in humans, no imipenem-resistant Enterobacterales were detected, whereas three Enterobacterales isolates were classified as resistant to meropenem. Differences between farms varied by bacterial group and antimicrobial agent. Many significant correlations in AMR were found among antibiotics, especially those within the same class. Different correlations among antibiotics were found across bacterial groups, including Enterobacterales, staphylococci, enterococci, and streptococci. Phenotypic associations were observed among antimicrobial susceptibility classifications, particularly for agents within the same class. These associations do not establish shared resistance mechanisms or predict treatment outcomes. Findings based on extrapolated thresholds require validation using appropriate susceptibility testing methods.
Related
- Metabolomic Profiling Screening for Molecular Level Associations Related to Cashmere Quality Related Phenotypic Types in Liaoning Cashmere Goats
- Phenotypic Variation Characterization and Multiple-Method Analysis of Drought Resistance in Rice at the Germination Stage
- Antimicrobial resistance at the animal / environment interface: phenotypic detection and persistence of ESBL and carbapenemase producing Enterobacterales in Irish cattle systems
- Antifungal Resistance and Adhesin-Mediated Phenotypic Plasticity Among Genomically Diverse Candida auris Clinical Isolates
- Phenotypic and genotypic screening for root-knot nematode (Meloidogyne incognita) resistance in tomato
BibTeX
@article{dim2026phenotypic,
title = {{Phenotypic Associations in Resistance to Medically Important Antibiotics Among Highly Resistant Bacteria Isolated from Cambodian Dairy Farms.}},
author = {Kanan Dim and Sho Nakamura and Soriya Rin and Sophorn Nouv and Sambo Na and Panhavatey Sokhom and Shuichi Matsuyama and Satoshi Ohkura and Witaya Suriyasathaporn},
journal = {Biology},
year = {2026},
month = oct,
doi = {10.3390/biology15201871},
url = {https://europepmc.org/article/MED/42939472},
note = {CC BY},
}
RIS
TY - JOUR
TI - Phenotypic Associations in Resistance to Medically Important Antibiotics Among Highly Resistant Bacteria Isolated from Cambodian Dairy Farms.
AU - Kanan Dim
AU - Sho Nakamura
AU - Soriya Rin
AU - Sophorn Nouv
AU - Sambo Na
AU - Panhavatey Sokhom
AU - Shuichi Matsuyama
AU - Satoshi Ohkura
AU - Witaya Suriyasathaporn
PY - 2026
DA - 2026/10/16
JO - Biology
DO - 10.3390/biology15201871
UR - https://europepmc.org/article/MED/42939472
AB - Antimicrobial resistance (AMR) is recognized by global health authorities as one of the foremost public health and development challenges confronting humanity today, leading the WHO to establish categories of medically important antibiotics for humans and animals. On farms with a high burden of infection, inappropriate antibiotic use, mixed bacterial infections, and environmental contamination with antibiotics from animal sources might accelerate the development of antibiotic resistance, particularly from a One Health Approach. Therefore, this study was conducted to determine correlations in AMR among antibiotics using bacteria isolated from dairy farms with a high burden of intramammary infections. In addition, antibiotic resistance percentages were compared between a smallholder dairy farm and an intensive dairy farm in Cambodia, where the dairy industry has been established for only a few years. Bacterial isolates were collected from two dairy farms: Farm A, a medium-sized local farm with approximately 30 milking cows, and Farm B, a large intensive farm with approximately 480 milking purebred Holstein-Friesian milking cows. All bacteria were tested for antimicrobial susceptibility using a disk diffusion test with 17 antibiotics from nine classes. Classifications based on CLSI interpretive criteria were distinguished from those based on study-defined, extrapolated inhibition-zone thresholds, designated expected AMR (AMR-E). The latter classifications were exploratory and were not validated measures of resistance. The antimicrobials included antibiotics from classes important in human medicine: human-used only (HU), highest-priority critically important antimicrobials (HPCIA), critically important antimicrobials (CIAs), and highly important antimicrobials (HIAs). Fisher's exact test was used to compare AMR between farms (p < 0.05), and Spearman's correlation adjusted by a Benjamini-Hochberg (Q < 0.05) was used to evaluate associations among antimicrobial susceptibility classifications and between these classifications and multidrug resistance (MDR) status. The results showed that the distribution of bacteria differed between the two farms. For antibiotics used only in humans, no imipenem-resistant Enterobacterales were detected, whereas three Enterobacterales isolates were classified as resistant to meropenem. Differences between farms varied by bacterial group and antimicrobial agent. Many significant correlations in AMR were found among antibiotics, especially those within the same class. Different correlations among antibiotics were found across bacterial groups, including Enterobacterales, staphylococci, enterococci, and streptococci. Phenotypic associations were observed among antimicrobial susceptibility classifications, particularly for agents within the same class. These associations do not establish shared resistance mechanisms or predict treatment outcomes. Findings based on extrapolated thresholds require validation using appropriate susceptibility testing methods.
SN - 2079-7737
ER -