Assessment of Antibiotic Susceptibility and Biofilm Formation in Bacteria Isolated from White-Leg Shrimp in Traditional Markets, Can Tho City, Vietnam

Tran, Hau Huu and Huynh, Nhi Thao and Tran, Nam Van Be and Le, Thanh Uyen and Huynh, Tam Ngoc Thanh (2026) Assessment of Antibiotic Susceptibility and Biofilm Formation in Bacteria Isolated from White-Leg Shrimp in Traditional Markets, Can Tho City, Vietnam. World's Veterinary Journal. 259 - 270. ISSN 23224568

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Abstract

In shrimp aquaculture, antibiotics are used to control bacteria, particularly species capable of growing on thiosulfate citrate bile salts sucrose (TCBS) agar. However, the overuse of antibiotics may lead to the emergence of antibiotic-resistant bacteria and the presence of antibiotic residues in food products. The present study aimed to evaluate the antibiotic susceptibility of bacterial isolates recovered from market shrimp against nine antibiotics, as well as their biofilm-forming capacity. The investigation focused on isolating bacteria capable of growing on TCBS agar, assessing antibiotic susceptibility using the disk diffusion method, and determining biofilm formation by the 1 crystal violet staining assay. From four shrimp samples collected at local markets, a total of 18 bacterial isolates were obtained, exhibiting yellow, green, and black colonies on TCBS agar. All isolates were resistant to at least one antibiotic and were capable of forming biofilms. Specifically, all 18/18 isolates were resistant to cefotaxime (100), while resistance rates to azithromycin, ampicillin, and erythromycin ranged from 77.8 to 83.3. Lower resistance frequencies were observed for doxycycline, tetracycline, and trimethoprim-sulfamethoxazole (16.7-22.2), and only 5.6 of isolates were resistant to ciprofloxacin. Notably, all isolates remained susceptible to levofloxacin (100). The multiple antibiotic resistance (MAR) index indicated that different isolates exhibited high levels of multidrug resistance, particularly Mar2.2, Mar3.4, and Mar3.5 (MAR = 0.67). Moreover, all 18 isolates demonstrated biofilm-forming ability, with Mar1.2, Mar2.4, and Mar4.4 producing significantly greater biofilm biomass compared to the remaining isolates. Phylogenetic analysis based on 16S rRNA gene sequencing revealed that Mar1.2 and Mar2.2 belonged to the genus Vibrio, Mar2.4 and Mar4.4 were assigned to the genus Shewanella, whereas Mar3.4 and Mar3.5 were classified within the genus Providencia. © The Author(s) 2026. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit https://creativecommons.org/licenses/by/4.0/.

Item Type:	Article
Keywords:	Antibiotic; Biofilm; Marketable whiteleg shrimp; Providencia; Shewanella; Vibrio
Subjects:	S Agriculture > SF Animal culture
Divisions:	World's Veterinary Journal (WVJ)
Page Range:	259 - 270
Journal or Publication Title:	World's Veterinary Journal
Journal Index:	Scopus
Volume:	16
Number:	1
Publisher:	Scienceline Publication
Identification Number:	https://doi.org/10.54203/scil.2026.wvj25
ISSN:	23224568
Depositing User:	Dr. Alireza Sadeghi
URI:	https://eprints.science-line.com/id/eprint/1702

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