Fig 1.
Biofilm bead reactor for low shear, high-throughput growth of biofilms on 50 substrates.
(A) S. aureus biofilm growth in the bead reactor. (B) Fifty glass beads were stabilized by a 100 mm × 50 mm insert in a petri dish.
Fig 2.
Standardized BioSurface Technologies CDC Biofilm Reactor® for dynamic, high-shear biofilm growth on 24 coupons.
(A) S. aureus biofilm grown in 100% BHI. (B) Image of empty CDC Biofilm Reactor® reprinted with permission from BioSurface Technologies.
Fig 3.
Representative images of S. aureus biofilm grown on CDC Biofilm Reactor® coupons and 4 mm diameter glass beads.
(A) 500x image of biofilm on a coupon. (B, C) at 1000x, coupon biofilm exhibited thick, multilayered plumes. (D) 500x image of bead biofilm. (E, F) 1000x images of bead biofilm also displayed multiple plumes that appeared slightly less dense than biofilm grown on coupons.
Fig 4.
Representative images of P. aeruginosa biofilm grown on glass coupons and beads.
(A) 500x image of CDC Biofilm Reactor® coupon that, like (B and C) 1000x images, revealed even sheets of P. aeruginosa. (D) 500x image of bead biofilm with cracking due to fixation of biofilm onto rounded glass surfaces. (E,F) 1000x images of bead biofilm confirm multilayered sheets of P. aeruginosa growth.
Fig 5.
Bioburden in log10 CFU per mm2 growth surface area of S. aureus and P. aeruginosa biofilm.
The average (n = 18 bead, n = 17 coupon) of substrates from 3 trials are represented by grey and striped bars. Each black dot denotes an individual quantified substrate. There was a significant difference between coupon and bead S. aureus biofilm growth (p = 0.003). This was not the case for P. aeruginosa.
Table 1.
MIC of ertapenem, moxifloxacin, and tobramycin against S. aureus and P. aeruginosa.
Fig 6.
S. aureus bioburden reduction calculated in log10 CFU per mm2 growth surface area.
Bead and coupon biofilms were treated for 24 h of in 100 µg/mL antibiotic suspended in 50% BHI broth. Each bar represents the average bioburden of 18 samples. Solid grey represents the CDC Biofilm Reactor® coupons and diagonal lines the bead reactor. Black dots denote the specific CFU of each bead quantified (n = 18 per bar). There was a significant difference (p < 0.05) between the average bioburden of CDC and bead biofilm treated with ertapenem (p = 0.005) and tobramycin (p = 0.014).
Fig 7.
P. aeruginosa bioburden reduction in log10 CFU per mm2.
Biofilms were treated for 24 h in 100 µg/mL antibiotic suspended in 50% BHI broth. Solid grey bars represent the average CFU per three trials for CDC Biofilm Reactor® coupons and diagonal lines the beads. Black dots denote the specific CFU of each bead quantified (n = 6 per trial). There was a significant difference (<0.05) between average bioburden reduction of tobramycin-treated coupons and beads (p = 0.035).