Study of frequency and antimicrobial resistance of Lactococcus garvieae in rainbow trout fish in Chaharmahal va Bakhtiari Province

Introduction: Lactococcus garvieae is the causative agent of lactococosis in fish which is transmittable to human in the case of contact or consumption of infected fish. The bacteria has been highly prevalent in fish farms. Materials and methods: In this study, frequency and antimicrobial resistance of L. garvieae was studied in rainbow trout fish farms in Chaharmahal va Bakhtiari Province. A total of 100 fish from 33 fish farms were collected in summer 2013 and were transmitted to the laboratory in appropriate conditions. The isolates were identified using biochemical tests and PCR. Results: The results indicated that fish from 23 out of 33 studied farms were infected with L. garvieae and 49 isolates were collected from the fish. The results also represented multi drug resistance of all isolates to common antibiotics. Minimum and maximum resistance was 30.7 and 65.4% for gentamicin and enrofloxacin, respectively. Discussion and conclusion: Infection of fish in more than 76 percent of the studied fish farms and high drug resistance of Lactococcus is a serious danger for aquaculture and for public health. Moreover, ability to infect humans and countless problems due to transmission of antimicrobial resistance to other bacteria reduplicates the importance of controlling the disease and surveillance on using antimicrobials in fish farms