Figure 1.
Electrophoresis plasmid profile of pRST98.
Lane M1, S. flexneri24570, plasmid size marker; Lane M2, E. coli V517, plasmid size marker; Lane 1–3, multi-drug resistant S. Typhi used as representative strains that naturally harbored pRST98 and were resistant to chloramp henicol, streptomycin, trimethoprim and sulphonamide, gentamicin, neomycin, kanamycin, cephalosporin ampicillin, carbenicillin and tetracycline; Lane 4, antibiotic-sensitive S. Typhi, which were plasmid free, and used as the negative control.
Table 1.
Strains used in this study.
Figure 2.
Comparison of BF developed by different bacteria.
(A) Different bacteria cultured in vitro for 3 d in microtiter plates at 30°C and stained by crystal violet (400×). (B) Different bacteria cultured in vitro for 3 d in 96-well plates at 30°C and stained by crystal violet. (C) Optical density of cultures measured at a wavelength of 570 nm (OD570) after crystal violet staining (*p <0.05).
Figure 3.
Different bacteria were cultured in 24-well plates for 3 d, and the developed pellicles were harvested, placed on glass slides, and subjected to 3D image reconstruction by CLSM.
Figure 4.
Different bacteria were cultured in 24-well plates for 3 d, and the developed pellicles were harvested, placed on glass slides, and subjected to SEM.
Figure 5.
Bacterial accumulation at the indicated time points and the bacterial load in the organs of CT26 tumor mice.
(A) Tumor-bearing mice were infected with 1×107 CFU of S. Typhimurium χ3337lux and χ3337lux/pRST98. The bioluminescence signals were captured by IVIS at the indicated time points. (B) Comparison of χ3337lux and χ3337lux/pRST98 accumulated in tumors at 3 d p.i. by SEM. (C) CFU counts of tumors, livers and spleens infected by χ3337lux or χ3337lux/pRST98. (**p <0.01); (*p <0.05)
Figure 6.
PE10 tubes recovered from the mouse urethral catheter model and histological changes of livers and kidneys.
(A) Analysis of K12W1485 and K12W1485/pRST98 BF on PE10 tubes at 5 d p.i. by SEM. (B) Quantification of K12W1485 and K12W1485/pRST98 colonizing on PE10 tubes at 5 d p.i. (p <0.05). Dots and dashes indicate the cfu of K12W1485 and K12W1485/pRST98, respectively, recovered from BF on PE10 tubes. The middle long horizontal line represents the mean cfu, and the short line represents the SD, (**p <0.01). (C) The tubes recovered from mice after urethral catheter at 5 d p.i. were washed with PBS and stained with AO, and bacteria were detected by CLSM. (D) H&E staining of livers and kidneys at 8 d after application of urethral catheter. (a and b), Livers of mice infected with K12W1485. (c and d), Kidneys of mice infected with K12W1485. (e and f), Livers of mice infected with K12W1485/RST98. (g and h), Kidneys of mice infected with K12W1485/pRST98.
Figure 7.
The effect of AHLs on rck expression and its related function.
(A) The adherence rate of S. Typhi to HeLa cells in the presence of AHLs (*p <0.05). (B and C) Quantification by CFU of surviving bacteria after incubation with sera from rabbits (B) and guinea pigs (C) in the presence of AHLs and saline (*p <0.05).
Figure 8.
The locus of rck and its expression.
(A) PCR of rck gene in pRST98. M: 1000 bp DNA ladder; Lane 1: S. Typhi ST8; Lane 2: S. Typhi ST8-ΔpRST98; Lane 3: S. Typhi ST8-c-pRST98. (B) The effect of AHLs on the expression of the rck gene. M: 1000 bp DNA ladder; Lane 1: S. Typhi ST8 treated with AHLs; Lane 2: S. Typhi ST8 treated with saline; Lane 3: S. typhi ST8-c-pRST98 treated with AHLs; Lane 4: S. Typhi ST8-c-pRST98 treated with saline; Lane 5: S. Typhi ST8-ΔpRST98 treated with AHLs; Lane 6: S. Typhi ST8-ΔpRST98 treated with saline.
Figure 9.
AHLs on S. Typhi BF formation.
S. Typhi, cultured in 24-well polystyrene plates for 24 h by adding 1µM C8-AHLs and 1µM saline and detected by IVIS. a,b: ST8lux; c,d: ST8-ΔpRST98lux; e,f: ST8-c-pRST98lux.