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Comparison of In Vitro Antimicrobial Susceptibility in Flavobacterium psychrophilum Isolated from Rainbow Trout Fry
Author(s) -
Kum Cavit,
Kirkan Sukru,
Sekkin Selim,
Akar Ferda,
Boyacioglu Murat
Publication year - 2008
Publication title -
journal of aquatic animal health
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.507
H-Index - 52
eISSN - 1548-8667
pISSN - 0899-7659
DOI - 10.1577/h07-040.1
Subject(s) - florfenicol , agar dilution , biology , microbiology and biotechnology , minimum inhibitory concentration , enrofloxacin , agar , agar diffusion test , flavobacterium , antimicrobial , gentamicin , tetracycline , oxytetracycline , rainbow trout , veterinary medicine , antibiotics , ciprofloxacin , bacteria , antibacterial activity , fish <actinopterygii> , fishery , medicine , genetics , pseudomonas
Abstract The aim of this study was to demonstrate the presence of Flavobacterium psychrophilum in the west Aegean region of Turkey and to evaluate the in vitro susceptibility of F. psychrophilum (isolated from the fry of rainbow trout Oncorhynchus mykiss ) to seven antimicrobial agents, as determined by the disk diffusion and agar dilution methods. A total of 250 rainbow trout fry (weight = 2–5 g; total length = 3–6 cm) were examined, and 20 bacterial isolates were phenotypically identified. Antimicrobial agents included in this investigation were amoxicillin–clavulanic acid (AMC), erythromycin (E), enrofloxacin (ENR), florfenicol (FFC), gentamicin (CN), oxytetracycline (OT), and sulfamethoxazole–trimethoprim (SXT). Disk diffusion and agar dilution methods were performed according to published standards. Minimum inhibitory concentration (MIC) ranges were determined using the agar dilution method for F. psychrophilum isolates. Resistance of F. psychrophilum to CN (disk diffusion method: 70%; agar dilution method: 95%), E (65%; 100%), and SXT (75%; 100%) was high using both methods. Resistance to ENR (10%; 15%) and FFC (25%; 25%) was low with both methods; MIC 90 (minimum concentration required to inhibit bacterial growth by 90%) was 4 μg/mL for ENR and 16 μg/mL for FFC. Ninety percent of the F. psychrophilum isolates were resistant to AMC based on the disk diffusion method, while only 15% of isolates showed resistance based on the agar dilution method. For OT, 20% of isolates were resistant based on disk diffusion, while 75% exhibited resistance based on agar dilution. The importance of susceptibility testing when facing an outbreak of F. psychrophilum at a fish farm is obvious; however, the discrepancies between testing methods for AMC and OT require further studies.