Investigating the antibiotic resistance pattern of Streptococcus iniae and Yersinia ruckeri isolated from rainbow trout in North Khorasan province, Iran

BACKGROUND AND ABJECTIVEDuring the last few years, streptococcosis and yersiniosis have been important problems in cold water fish farms in Iran, causing huge economic losses to the rainbow trout production industry. Knowing the level of resistance and sensitivity of problematic bacteria such as Yersinia ruckeri and Streptococcus iniae in rainbow trout breeding farms plays an effective role in the appropriate and correct selection of antibiotics and infection control in breeding ponds.MATERIALS AND METHODSIn this research, considering the prevalence of streptococcosis and yersiniosis, ۱۰۰ pieces of rainbow trout with clinical symptoms of streptococcosis and yersiniosis were harvested from rainbow trout farms located in North Khorasan province in the hot seasons. After performing bacteriological culture and isolation of Streptococcus iniae and Yersinia ruckeri species, it was finally confirmed by using PCR test with specific primers. Antibiotic sensitivity of bacteria was investigated by disc diffusion method by culturing on Mueller Hinton agar culture medium.RESULTS AND DISCUSSIONThe results of bacteriological and molecular diagnosis show that the main cause of bacterial diseases in rainbow trout in North Khorasan province is Yersinia ruckeri (۸۷%). And in ۱۳% of disease cases, Streptococcus iniae was also detected. The results of the antibiogram of Yersinia ruckeri isolates showed that they have the highest resistance to Amoxicillin, Tylosin, Erythromycin, Gentamicin and the highest sensitivity to Enrofloxacin, Florfenicol, Lincospectin, and Oxytetracycline. Streptococcus iniae isolates also showed the highest sensitivity to Enrofloxacin, Florfenicol, Doxycycline, and the highest resistance to Bacitracin, Penicillin, and Trimethoprim, respectively.CONCLUSIONIn order to prevent the increase of resistance, the indiscriminate use of antibiotics should be prevented and bacterial culture and antibiogram test should be done before use. Selfmedication and indiscriminate use of antibiotics will cause drug resistance in pathogenic bacteria and irreparable consequences such as drug residue and drug resistance in humans

کلیدواژه ها:

Yersinia ruckeri ، Streptococcus iniae ، Antibiotic resistance pattern