Table 7. Mechanisms of streptomycin resistance in Erwinia amylovora
|
Genetic mechanism |
Effect |
MIC (ppm)1 |
Occurrence in
Erwinia amylovora |
|
Mutation in the bacterial gene rpsL, which encodes a subunit of a bacterial ribosome |
Streptomycin cannot bind to mutant ribosome |
> 2,000 |
Chromosomal mutation; prevalent in the western US, Israel, and New Zealand; also found in Michigan |
|
strA-strB |
Encodes an enzyme (phosphotransferase) that inactivates streptomycin |
500-750 |
Usually associated with transposon Tn5393 on plasmids; prevalent in Michigan; also found in California |
1Minimal inhibitory concentration (in parts per million): the lowest concentration of antibiotic that
completely inhibits bacterial growth.
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