TABLE 1

Characteristics of multidrug-resistant A. salmonicida subsp. salmonicida isolates harboring a tetracycline resistance gene

IsolateaAntibiotic resistancebMIC (μg/ml) for tetracyclinecPlasmids foundd
01-B522SXT, TET, TMP128Cryptic, pAsal1, pAsa5, pAsa4-like
07-9324STR, AMP, TET, CHL16Cryptic, pAsal1, pAsa5, pSN254-like
07-7817STR, AMP, TET, CHL16Cryptic, pAsal1, pAsa5, pSN254-like
08-2647SXT, STR, AMP, TET16Cryptic, pAsal1, pAsa5, pSN254-like
07-7287STR, AMP, TET, CHL16Cryptic, pAsal1, pAsa5, pSN254-like
08-2783STR, AMP, TET16Cryptic, pAsal1, pAsa5, pSN254-like
08-4188STR, AMP, TET, CHL16Cryptic, pAsal1, pAsa5, pSN254-like
2009-157K5STR, TET, ERY128Cryptic, pAsal1, pAsa5, pRas3.3
2010-47K18STR, TET, CHL128Cryptic, pAsal1, pAsa5, pRas3.4, pAB5S9-like
2004-05MF26NAL, SXT, STR, AMP, TET, ERY, GEN, CHL16Cryptic, pAsal1, pAsa5, pSN254b
2004-68K52NAL, SXT, STR, AMP, TET, CHL64Cryptic, pAsal1, pAsa5, pSN254-like
2009-195K29STR, TET, ERY32Cryptic, pAsal1, pAsa5, pRas3.3
2009-144K3SXT, STR, TET, ERY, CHL256Cryptic, pAsal1, pAsa5, pRas3.3, pAB5S9b
M15448-11STR, AMP, TET, CHL32Cryptic, pAsal1, pAsa5
M16474-11STR, AMP, TET, ERY, CHL32Cryptic, pAsal1, pAsa5
M14481-11SXT, STR, AMP, TET, CHL16Cryptic, pAsal1, pAsa5, pSN254-like
M15879-11SXT, STR, AMP, TET, CHL16Cryptic, pAsal1, pAsa5, pSN254-like
M17739-11SXT, STR, AMP, TET, CHL16Cryptic, pAsal1, pAsa5, pSN254-like
M13732-11STR, AMP, TET, CHL16Cryptic, pAsal1, pAsa5, pSN254-like
M17053-11STR, AMP, TET, CHL16Cryptic, pAsal1, pAsa5, pSN254-like
M15469-11STR, AMP, TET, CHL16Cryptic, pAsal1, pAsa5, pSN254-like
  • a The origin and source of these isolates are given in Table S1 in the supplemental material.

  • b NAL, nalidixic acid; SXT, sulfamethoxazole-trimethoprim; STR, streptomycin; AMP, ampicillin; TET, tetracycline; ERY, erythromycin; GEN, gentamicin; TMP, trimethoprim; CHL, chloramphenicol.

  • c The MIC of the sensitive 01-B526 isolate was 0.5 μg/ml.

  • d The three cryptic plasmids pAsa1, pAsa2, and pAsa3, as well as pAsal1 and pRAS3, were identified in these isolates in a previous study by Trudel et al. (9). The pAsa5, pAsa4-like, pAB5S9-like, and pSN254-like plasmids were found by PCR genotyping in the present study (see Table S2 in the supplemental material).