TABLE 2.

Tetracycline MIC values for M. elsdenii strains

M. elsdenii strain(s)atet genotypebMIC (μg/ml)c
TetOxytetChlortet
24-50; 27-50; 33-54 (LC-1T; B159; T81)No gene4-88-162-8
Fern tet(O)6464256
25-50; 29-55 tet(W)32-646464-128
24-51; 27-51; 25-51; 31-55 tet(OW)6464-128128-256
7-11 (2-9) tet(OWO)-1128256>256
24-53; 27-52; 33-56 (4-13; 7-12; 14-14; 15-5; 19-3; 20-11) tet(OWO)-2128256->256256->256
  • a Strain 7-11 was used as a M. elsdenii tetracycline-resistant reference strain in the assays. Tetracycline MIC values for M. elsdenii strains enclosed by parentheses have been reported previously (26).

  • b Genotypes are based on PCR assay results (Fig. 1; Table 1). Strains 27-51 and 25-51 had tet(OW)-1 and tet(OW)-2 genotypes, respectively, as identified by sequence analysis. Strains 25-50 and 29-55 had tet(W)-1 and tet(W)-2 genotypes, respectively.

  • c Tetracycline (Tet), oxytetracycline (Oxytet), and chlortetracycline (Chlortet) MIC values for NCCLS reference strain Bacteroides fragilis ATCC 25285 (Tcs) were 2, 8, and 4 μg/ml, respectively. For B. thetaiotaomicron ATCC 29741 (Tcr), the MIC value of all three antibiotics was 64μ g/ml.