Antimicrobial Resistance and Minimum Inhibitory Concentration Profiles of Flavobacterium oreochromis Isolated from Tilapia Cultured in Northern Vietnam

Date Received: Jul 15, 2025

Date Accepted: Oct 22, 2025

Date Published: Dec 31, 2025

DOI: https://doi.org/10.31817/vjas.2025.8.4.03

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Issue: Vol. 8 No. 4 (2025): Vietnam Journal of Agricultural Sciences

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ANIMAL SCIENCE – VETERINARY MEDICINE – AQUACULTURE

How to Cite:

Nhinh, D., Trinh, T., Hoa, D., Tuyen, N., Giang, N., & Hoai, T. (2025). Antimicrobial Resistance and Minimum Inhibitory Concentration Profiles of Flavobacterium oreochromis Isolated from Tilapia Cultured in Northern Vietnam. Vietnam Journal of Agricultural Sciences, 8(4), 2703–2714. https://doi.org/10.31817/vjas.2025.8.4.03

Antimicrobial Resistance and Minimum Inhibitory Concentration Profiles of Flavobacterium oreochromis Isolated from Tilapia Cultured in Northern Vietnam

Doan Thi Nhinh 1 , Tran Thi Trinh 1 , Dang Thi Hoa 1 , Nguyen Van Tuyen 1 , Nguyen Thi Huong Giang 2   , Truong Dinh Hoai (*) 1

  • Corresponding author: [email protected]
  • 1 Faculty of Fisheries, Vietnam National University of Agriculture, Hanoi 12400, Vietnam
  • 2 Faculty of Veterinary Medicine, Vietnam National University of Agriculture, Hanoi 12400, Vietnam

    • Keywords

    Flavobacterium oreochromis, tilapia, antimicrobial resistance, MIC

    Abstract


    Flavobacterium oreochromis is a major bacterial pathogen that causes columnaris disease in tilapia (Oreochromis spp.) and other freshwater fish species. This study assessed the antibiotic resistance profiles and minimum inhibitory concentrations (MICs) of F. oreochromis isolates obtained from infected tilapia cultured in Northern Vietnam. A total of 51 isolates retrieved from diseased fish collected in Hai Duong (n = 23), Bac Ninh (n = 16), and Hoa Binh (12 isolates) were used in the study. The bacteria were cultured on TYES agar, identified through morphological and biochemical analyses, and confirmed by PCR. Antimicrobial susceptibility testing employed the disk diffusion method against 15 antibiotics, while the MICs of six frequently used antibiotics were determined via the broth microdilution method. The antimicrobial susceptibility test revealed that the isolates exhibited high resistance to oxacillin (100%) and neomycin (76.5%), and moderate resistance to sulfamethoxazole-trimethoprim (37.3%), doxycycline (35.3%), and oxytetracycline (41.2%). Resistance values to the remaining antibiotics were below 12%. Notably, all the isolates were multidrug-resistant (MDR), exhibiting resistance to 2-10 antibiotics, and 14 distinct resistance phenotypes were identified. The MIC values ranged from 0.063-1 µg mL-1 for amoxicillin, 0.125-8 µg mL-1 for erythromycin, and 0.25-8 µg mL-1 for florfenicol. For oxytetracycline, doxycycline, and sulfamethoxazole-trimethoprim, the MICs ranged from 0.016-1 µg mL-1, 0.125-2 µg mL-1, and 0.5-16 µg mL-1, respectively. These findings highlight a decline in the efficacy of commonly used antibiotics against F. oreochromis, underscoring the necessity for routine antimicrobial susceptibility testing to promote rational antibiotic use in aquaculture.

    References

    Barony G., Tavares G., Assis G., Luz R., Figueiredo H. & Leal C. (2015). New hosts and genetic diversity of Flavobacterium columnare isolated from Brazilian native species and Nile tilapia. Diseases of aquatic organisms. 117(1): 1-11.

    Bernardet J.-F. & Bowman J. P. (2006). The genus Flavobacterium. Prokaryotes. 7: 481-531.

    Bernardet J.-F. & Grimont P. A. (1989). Deoxyribonucleic acid relatedness and phenotypic characterization of Flexibacter columnaris sp. nov., nom. rev., Flexibacter psychrophilus sp. nov., nom. rev., and Flexibacter maritimus Wakabayashi, Hikida, and Masumura 1986. International Journal of Systematic and Evolutionary Microbiology. 39(3): 346-354.

    Binh V. N., Dang N., Anh N. T. K. & Thai P. K. (2018). Antibiotics in the aquatic environment of Vietnam: sources, concentrations, risk and control strategy. Chemosphere. 197: 438-450.

    Cain K. D. & LaFrentz B. R. (2007). Laboratory maintenance of Flavobacterium psychrophilum and Flavobacterium columnare. Current Protocols in Microbiology. 6(1): 13B. 11.11-13B. 11.12.

    Chen J., Sun R., Pan C., Sun Y., Mai B., & Li Q. X. (2020). Antibiotics and food safety in aquaculture. Journal of Agricultural and Food Chemistry. 68(43): 11908-11919.

    CLSI (2015). Performance Standards For Antimicrobial Susceptibility Testing; Twenty-Fifth Informational Supplement. CLSI document M100-S25. Wayne, PA: Clinical and Laboratory Standards Institute. ISBN 1-56238-990-4.

    CLSI (2020). Performance Standards for Antimicrobial Testing of Bacteria Isolated from Aquatic Animals. 3rd ed. CLSI supplement VET04. Wayne, PA: Clinical and Laboratory Standards Institute. ISBN 1-56238-990-4.

    Declercq A., Boyen F., Van Den Broeck W., Bossier P., Karsi A., Haesebrouck F. & Decostere A. (2013a). Antimicrobial susceptibility pattern of Flavobacterium columnare isolates collected worldwide from 17 fish species. Journal of Fish Diseases. 36(1): 45-55.

    Declercq A. M., Haesebrouck F., Van den Broeck W., Bossier P. & Decostere A. (2013b). Columnaris disease in fish: a review with emphasis on bacterium-host interactions. Veterinary Research. 44(1): 1-17.

    Dong H., LaFrentz B., Pirarat N. & Rodkhum C. (2015a). Phenotypic characterization and genetic diversity of Flavobacterium columnare isolated from red tilapia, Oreochromis sp., in Thailand. Journal of Fish Diseases. 38(10): 901-913.

    Dong H. T., Nguyen V. V., Phiwsaiya K., Gangnonngiw W., Withyachumnarnkul B., Rodkhum C. & Senapin S. (2015b). Concurrent infections of Flavobacterium columnare and Edwardsiella ictaluri in striped catfish, Pangasianodon hypophthalmus in Thailand. Aquaculture. 448: 142-150.

    Dong H., Senapin S., LaFrentz B. & Rodkhum C. (2016). Virulence assay of rhizoid and non‐rhizoid morphotypes of Flavobacterium columnare in red tilapia, Oreochromis sp., fry. Journal of Fish Diseases. 39(6): 649-655.

    Dung T. T., Haesebrouck F., Tuan N. A., Sorgeloos P., Baele M. & Decostere A. (2008). Antimicrobial susceptibility pattern of Edwardsiella ictaluri isolates from natural outbreaks of bacillary necrosis of Pangasianodon hypophthalmus in Vietnam. Microbial Drug Resistance. 14(4): 311-316.

    El-Tawab A., El-Hofy F., EL-Gamal R., Awad S., El-Mougy E. & Mohamed S. (2020). Phenotypic and genotypic characterization of Antibiotic resistant strains of Flavobacterium columnare isolated from Oreochromis niloticus (Nile tilapia). Benha Veterinary Medical Journal. 38(2): 141-145.

    Figueiredo H., Klesius P., Arias C., Evans J., Shoemaker C., Pereira Jr. D. & Peixoto M. (2005). Isolation and characterization of strains of Flavobacterium columnare from Brazil. Journal of Fish Diseases. 28(4): 199-204.

    Haenen O. L., Dong H. T., Hoai T. D., Crumlish M., Karunasagar I., Barkham T., Chen S. L., Zadoks R., Kiermeier A. & Wang B. (2023). Bacterial diseases of tilapia, their zoonotic potential and risk of antimicrobial resistance. Reviews in Aquaculture. 15: 154-185.

    Truong Thi My Hanh, Nguyen Thi Hanh, Le Thi May, Truong Thi Thanh Vinh & Dang Thi Lua (2024). Antimicrobial resistance in Streptococcus agalactiae in tilapia (Oreochromis sp.) farming in northern Vietnam. Vinh University Journal of Science. 53 (2A): 15-23 (in Vietnamese).

    Hedberg N., Stenson I., Pettersson M. N., Warshan D., Nguyen-Kim H., Tedengren M. & Kautsky N. (2018). Antibiotic use in Vietnamese fish and lobster sea cage farms; implications for coral reefs and human health. Aquaculture. 495: 366-375.

    Hoa P. T. P., Managaki S., Nakada N., Takada H., Shimizu, A., Anh D. H., Viet P. H. & Suzuki S. (2011). Antibiotic contamination and occurrence of antibiotic-resistant bacteria in aquatic environments of northern Vietnam. Science of the Total Environment. 409(15): 2894-2901.

    Hoai T. D., Nhinh D. T., Giang N. T. H., Van Van K. & Dong H. T. (2025). First report on Flavobacterium columnare causing disease outbreaks in cultured black carp, Mylopharyngodon piceus, in Northern Vietnam. Microbial Pathogenesis. 202: 107413.

    LaFrentz B. R., Králová S., Burbick C. R., Alexander T. L., Phillips C. W., Griffin M. J., Waldbieser G. C., García J. C., de Alexandre Sebastião F. & Soto E. (2022). The fish pathogen Flavobacterium columnare represents four distinct species: Flavobacterium columnare, Flavobacterium covae sp. nov., Flavobacterium davisii sp. nov. and Flavobacterium oreochromis sp. nov., and emended description of Flavobacterium columnare. Systematic and Applied Microbiology. 45(2): 126293.

    MARD (2019). Decision to approve the plan of tilapia farming development by 2020, driven by 2030 issued on May 6, 2016 by the Ministry of Agriculture and Rural Development, Vietnam (MARD) (in Vietnamese).

    Nhinh D. T., Giang N. T. H., Van Van K., Dang L. T., Dong H. T. & Hoai T. D. (2022). Widespread presence of a highly virulent Edwardsiella ictaluri strain in farmed tilapia, Oreochromis spp. Transboundary and Emerging Diseases. 69(5): e2276-e2290.

    Nhinh D. T., Le D. V., Van K. V., Huong Giang N. T., Dang L. T. & Hoai T. D. (2021). Prevalence, virulence gene distribution and alarming the multidrug resistance of Aeromonas hydrophila associated with disease outbreaks in freshwater aquaculture. Antibiotics. 10(5): 532.

    Nhinh D. T., Trinh T. T., Hoa D. T., Tuan N. N., Giang N. T. H., Van K. V., Lua D. T. & Hoai T. D. (2023). Study on isolation and some pathological characteristics of Flavobacterium columnare causing infection in tilapia (Oreochromis spp.) cultured in Northern Vietnam. Vietnam Journal of Science and Technology (B). 65(2): 41-47 (in Vietnamese).

    Prabu E., Rajagopalsamy C., Ahilan B., Jeevagan I. & Renuhadevi M. (2019). Tilapia–an excellent candidate species for world aquaculture: a review. Annual Research & Review in Biology. 31(3): 1-14.

    Preena P., Arathi D., Raj N. S., Arun Kumar T., Arun R., S., Reshma R. & Raja Swaminathan T. (2020). Diversity of antimicrobial‐resistant pathogens from a freshwater ornamental fish farm. Letters in Applied Microbiology. 71(1): 108-116.

    Romero J., Feijoó C. G. & Navarrete P. (2012). Antibiotics in aquaculture–use, abuse and alternatives. Health and Environment in Aquaculture. 159(1): 159-198.

    Santos L. & Ramos F. (2018). Antimicrobial resistance in aquaculture: Current knowledge and alternatives to tackle the problem. International Journal of Antimicrobial Agents. 52(2): 135-143.

    Soto E., Mauel M. J., Karsi A. & Lawrence M. (2008). Genetic and virulence characterization of Flavobacterium columnare from channel catfish (Ictalurus punctatus). Journal Of Applied Microbiology. 104(5): 1302-1310.

    Vignesh R., Karthikeyan B., Periyasamy N. & Devanathan K. (2011). Antibiotics in aquaculture: an overview. South Asian Journal of Experimental Biology. 1(3): 114-120.

    Wang M. & Lu M. (2016). Tilapia polyculture: a global review. Aquaculture Research. 47(8): 2363-2374.

    Watts J. E., Schreier H. J., Lanska L. & Hale M. S. (2017). The rising tide of antimicrobial resistance in aquaculture: sources, sinks and solutions. Marine Drugs. 15(6): 158.

    Welker T. L., Shoemaker C. A., Arias C. R. & Klesius P. H. (2005). Transmission and detection of Flavobacterium columnare in channel catfish Ictalurus punctatus. Diseases of Aquatic Organisms. 63(2-3): 129-138.