Akademik Veri Yönetim Sistemi
TARIM BILIMLERI DERGISI, cilt.29, sa.2, ss.630-642, 2023 (SCI-Expanded)
The continuity of
antimicrobial resistance development in bacteria changes the type and dose of
effective antibiotic treatments and makes routine monitoring studies necessary
for successful control of bacterial diseases. This study was aimed to determine
the current antibiotic susceptibility of Lactococcus
garvieae, which causes significant economic losses in rainbow trout (Oncorhynchus mykiss) farms. In the
study, two consecutive visits were made to three farms operating on the banks
of a stream during a disease outbreak in the fall of 2018. At each visit, 10
fish showing the signs of disease from each farm (60 fish in total) were
sampled and L. garvieae was isolated
from 16 fish. All isolates were identified using conventional and molecular methods.
Then, they were examined for 5 different antibiotic resistance genes and their
antibiotic susceptibility profiles were determined using the Kirby Bauer disc diffusion technique. Results of the disc
diffusion test revealed that all 16 isolates had a different antibiotic susceptibility
profile and the isolates with different antibiotic susceptibility profile could
exist within and between farms, using the same water source. Furthermore, they revealed
that highly resistant isolates that showed no susceptibility up to 82 to 100%
of the 33 antibiotics at the doses evaluated exist in all farms. All isolates
carried either tetA or tetB genes or both and the majority of
isolates carried tetA gene. Together
with this, 25% of the isolates which carried both or one of the resistance
genes showed susceptibility to all 4 tetracycline class antibiotics at the
doses evaluated. Results of the study and their comparison with previous
studies in the same production area or in different regions of the country
revealed the dynamic nature of antibiotic resistance development in L. garvieae. Additionally, it showed
that monitoring studies with a limited number of isolates may not give an
accurate picture of the current status of antibiotic resistance from a
production area. These results of the study were also discussed in terms of the
treatment strategies that trout farmers should follow when treating
lactococcosis