Evaluation of antibiotic resistance in Aeromonas hydrophila, Streptococcus iniae, Yersinia ruckeri

Introduction and Objectives: The aquaculture industry is very important to produce nearly one-third of the world’s seafood supplies. One of the biggest problems in this industry is bacterial infectious diseases. The aim of this study was to measure the susceptibility or resistance of 3 bacterial pathogens to antibiotics commonly used in treatment. Materials and Methods: After preparing bacterial culture from each specimen in Muller Hinton Broth medium, the samples were compared for opacity with 0.5 McFarland (108 bacterial). For antibiotic test bacterial was cultured on a Merck Germany medium and the effects of antibiotic disks were evaluated using the CLSI (Clinical and Laboratory Standard Institute) method. According to the standard, the diameter of the zone was determined to prevent the growth of bacteria. The absence of zone formation or diameter less than the sensitivity standard of bacteria was reported as resistance to the antibiotic. Antibiotic disks used in this study were obtained from the Iranian Antibacterial Medicine Company, which included: tetracycline 30 μg, amoxicillin 25 μg, ampicillin 10μg, erythromycin was 15 micro grams. So, after the bacterial culture of the bacteria on the agar culture medium, the antibiotic discs were incubated on the agar medium and incubated after 48-72 hours and after 5 days the diameter of the Growth bacterial was measured. Results: This research was based on three control treatments (Injection Streptococcus iniae, Yersinia ruckeri and Aeromonas hydrophila) and 15 treatments (3 bacteria and 5 antibiotics) were evaluated in 4 replications. Data analysis was performed using SPSS software version 18. For The results showed that there was a significant difference between the two aerobic bacteria of Aeromonas hydrophila during the 24 hours and the Yersinia ruckeri against antibiotic amoxicillin. In the case of Aeromonas hydrophila and Yersinia ruckeri, there was no significant difference between 24, 48, and 72 hours in the 3rd time, but the Streptococcus iniae had a significant difference with 48 hours and 72 hours with the first of 24 hours. Also, the data showed that 3 bacteria tested at different times showed no significant difference with the antibiotics of oxytracycline, but there was a significant difference in comparison with each other. In contrast to erythromycin, there was a significant difference between different times for Aeromonas hydrophila bacteria but there was no significant difference for Streptococcus iniae infection in different times. In the case of Yersinia ruckeri bacteria, there was a significant difference between 48 hours and 24 hours and 72 hours. Against tetracycline, there was a significant difference in the Yersinia ruckeri time of 24 hours with two other times.Conclusion: The bacteria of these 3 bacterial pathogens are still susceptible to 5 antibiotics and can be introduced for the treatment of aquatic diseases.

کلیدواژه ها:

Aquatic Disease Bacteria ، Antibiotic Disc ، Zone of Growth