TABLE 2.

Characteristics of donors and transconjugants and frequency of transfer of ampicillin resistance

E. faecium donor straina (drug resistance)Transconjugant (drug resistance)Transfer frequency
C68 (Apr Vmr)CV384 (Apr Vms)3.3 × 10−8
TX0016 (Apr Vms)CV477 (Apr Vms)5.3 × 10−10
D14 (Apr Vms)None<5 × 10−10
D24 (Apr Vms)CV465 (Apr Vms)7.14 × 10−9
D25 (Apr Vms)Colonies appeared on plates but did not regrow on ampicillinUnknown
D29 (Apr Vms)CV420 (Apr Vms)1.35 × 10−7
TJ386 (Apr Vmr)CV426 (Apr Vms)5.7 × 10−9
WB312 (Apr Vmr)CV433 (Apr Vmr)1 × 10−9
WC176 (Apr Vmr)CV437 (Apr Vms)2.56 × 10−7
T420 (low-level Apr, Vms)NoneUnknownb
T450 (low-level Apr, Vms)None<5 × 10−10
T471 (low-level Apr, Vms)CV343 (low-level Apr, Vms)3.3 × 10−9
T636 (low-level Apr, Vms)CV470 (low-level Apr, Vms)3.08 × 10−9
T642 (low-level Apr, Vms)CV472 (low-level Apr, Vms)3.28 × 10−9
D344R (Apr Vms)CV333 (Apr Vms)3.3 × 10−8
  • a Recipient strain for all matings was E. faecium D344SRF.

  • b No recipients grew on colony-counting plates, suggesting a donor-killing recipient.