Physiological costs due to mutations in the 23S rRNA gene associated with Azmr in C. caviae SP6

C. caviae strain23S rRNA mutationaPlaque sizeb (mm)Duration of eclipse phase (h)cRate of 2-fold EB increase (min)c,eEB generation rate (fold increase)fCompetition indexg at indicated no. of passages
One (43 h p.i.)Two (86 h p.i.)h
SP6None (wild type)0.98 ± 0.1419201,530 ± 427NANA
SP6AZ1A2058C0.65 ± 0.1319-22d29113 ± 510.15 ± 0.030.06 ± 0.01
SP6AZ2A2059C0.46 ± 0.172221.6256 ± 940.28 ± 0.050.17 ± 0.07
  • a E. coli numbering system.

  • b The sizes of a minimum of 34 individual plaques were determined for each strain in the absence of antibiotic at 7 days p.i. and averaged.

  • c Data obtained from Fig. 1.

  • d The eclipse phase lasted for more than 19 h but less than 22 h.

  • e The rate of 2-fold EB increase was estimated as described in Materials and Methods.

  • f The number of IFU produced at 43 h p.i. divided by the number used at the time of infection was different for each of the three C. caviae strains (P < 0.0001; t test).

  • g The competition index is defined as the ratio of the output mutant/wild-type ratio at the indicated time p.i. to the input mutant/wild-type ratio. NA, not applicable.

  • h Determined after a second 43-h passage.