The indiscriminate and improper use of antibiotics in shrimp farming can have a number of negative consequences, including the development of drug-resistant bacteria that render disease prevention and treatment ineffective, negatively impact the user’s health, and alter the natural microflora. In addition, exporting and consuming farmed shrimp items that have antibiotic residues will be also prohibited. The aim of this study was to detect antibiotic-resistant Vibrio species in extensive white leg shrimp farming systems in Thua Thien Hue, Vietnam. Microbial culture techniques were utilized to isolate Vibrio, determine antibiotic resistance, and estimate the minimal bacterial inhibitory concentration. The species of Vibrio were identified using 16S rRNA sequencing, and a phylogenetic tree was constructed using the maximum likelihood estimation with a bootstrap of 1000 replications. The results showed the supply brackish water consisted of 102.5–103.8 CFU/mL of Vibrio. After 3 months of cultivation, the Vibrio concentration in white leg shrimp ponds increased rapidly, reaching 104–106.6 CFU/mL. Antibiotic susceptibility testing demonstrated the antibiotic resistance of Vibrio present in supply brackish water. Vibrio bacteria in shrimp ponds were resistant to gentamicin, kanamycin, streptomycin, oxytetracycline hydrochloride, and doxycycline, up to 98.87% of the antibiotics tested, ciprofloxacin was the most potent inhibitor of Vibrio. MIC evaluation of ciprofloxacin-resistant Vibrio isolates showed that they were resistant to many other antibiotics. This discovery demonstrates the need for using the optimum antibiotics in white leg shrimp farming to prevent the dissemination of antibiotic-resistant Vibrio bacteria.
Key words: Vibrio, antibiotic resistance, shrimp, ciprofloxacin
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