Table 4.

Bacterial invasion of Henle cells and recovery of bacteria from cells

Expt and strainTime postinfection (h)Invasion ratioaNo. of bacteria counted/ infected Henle cellbBacterial CFU recovered/infected Henle cellc
Expt 1
 SA511 (WTd)21.0013.8 ± 0.710.7 ± 4.5
31.0843.8 ± 7.433.9 ± 8.0
 SA212221.0111.7 ± 2.40.2 ± 0.1
31.0934.4 ± 4.50.9 ± 0.9
Expt 2
 SA100 (WTd)21.00ND31.3 ± 4.8
 SA512220.81ND3.2 ± 0.3
 SA5122(pMQA)20.83ND30.2 ± 5.1
 SA5122(pMQB)20.82ND6.7 ± 1.4
  • a Invasion ratio = percentage of Henle cells invaded by the mutant/percentage of cells invaded by the parental strain.

  • b Values are average numbers of intracellular bacteria counted in three separate fields of at least 20 infected Henle cells per field ± standard deviations.

  • c Bacterial CFU recovered per infected Henle cell = (total bacterial CFU recovered per plate)/(total number of Henle cells harvested per plate × percentage of Henle cells infected).

  • d WT, wild type.