TABLE 5.

Insertional inactivation of pilQ and pilT in FA1090 decreased sensitivities to ERY, RIF, and TX-100

StrainaMean zone of growth inhibition (mm)b ± SD with:
AMP (2 μg)ERY (0.5 μg)RIF (0.1 μg)TX-100 (10 μl of a 1:100 dilution)
FA1090 P+, Hb+17.6 ± 1.119.8 ± 3.518.0 ± 1.011.0 ± 1.0
FA1090 P, Hb+18.2 ± 1.520.2 ± 3.318.4 ± 1.511.0 ± 1.6
FA7311 (FA1090 pilQ::Ω), Hb+18.0 ± 1.118.8 ± 4.3*16.0 ± 2.1*9.3 ± 1.0**
FA7348 (FA1090 pilT::tet), Hb+18.3 ± 1.518.7 ± 3.0*16.2 ± 1.0*9.5 ± 0.8*
  • a For FA1090, phenotypically piliated (P+) and nonpiliated (P) colonies were selectively passed in preparation for the following day's experiment.

  • b Each value is an average of five zones of growth inhibition obtained with the indicated amount of antimicrobial agent measured from five experiments after 48 h of incubation. A paired t test showed significant differences (*, P < 0.05; **, P < 0.01) as indicated compared to FA1090 P+.