Characterization of Renibacterium salmoninarum with reduced susceptibility to macrolide antibiotics by a standardized antibiotic susceptibility test
| Autor: | Lee W. Harrell, Marilyn C. Roberts, Oanh T. Nguyen, Rebecca K. Deinhard, Linda D. Rhodes, Teresa M. White |
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| Rok vydání: | 2008 |
| Předmět: |
DNA
Bacterial medicine.drug_class Antibiotics Colony Count Microbial Erythromycin Microbial Sensitivity Tests Aquatic Science Biology Azithromycin medicine.disease_cause Kidney DNA Ribosomal Macrolide Antibiotics Microbiology Minimum inhibitory concentration Fish Diseases Open Reading Frames 23S ribosomal RNA Salmon medicine Animals Renibacterium salmoninarum Ecology Evolution Behavior and Systematics Dose-Response Relationship Drug Anti-Bacterial Agents RNA Ribosomal 23S Bacterial kidney disease Mutation Kidney Diseases Macrolides Actinomycetales Infections medicine.drug Micrococcaceae |
| Zdroj: | Diseases of aquatic organisms. 80(3) |
| ISSN: | 0177-5103 |
| Popis: | Three cohorts of juvenile and subadult Chinook salmon Oncorhynchus tshawytscha received multiple treatments with macrolide antibiotics for bacterial kidney disease (BKD) during rearing in a captive broodstock program. A total of 77 mortalities among the cohorts were screened for Renibacterium salmoninarum, the etiologic agent of BKD, by agar culture from kidney, and isolates from 7 fish were suitable for growth testing in the presence of macrolide antibiotics. The minimum inhibitory concentration (MIC) of erythromycin and azithromycin was determined by a modification of the standardized broth assay using defined medium. The American Type Culture Collection (ATCC) type strain 33209 exhibited a MIC of 0.008 microg m(-1) to either erythromycin or azithromycin. Isolates from 3 fish displayed MICs identical to the MICs for the ATCC type strain 33209. In contrast, isolates from 4 fish exhibited higher MICs, ranging between 0.125 and 0.250 microg ml(-1) for erythromycin and between 0.016 and 0.031 microg ml(-1) for azithromycin. Sequence analysis of the mutational hotspots for macrolide resistance in the 23S rDNA gene and the open reading frames of ribosomal proteins L4 and L22 found identical sequences among all isolates, indicating that the phenotype was not due to mutations associated with the drug-binding site of 23S rRNA. These results are the first report of R. salmoninarum with reduced susceptibility to macrolide antibiotics isolated from fish receiving multiple antibiotic treatments. |
| Databáze: | OpenAIRE |
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