Figure 3 P. aeruginosa biofilm cell counts for various contact lens materials after 24, 48 and 72 h of growth. Results are the means of data performed in quadruplicate (± standard deviation) in log [CFU/cm2] at the different incubation times: 24 h (light grey), 48 h (middle grey) and 72 h (dark grey). Table 3 Results of analysis of variance: main effects of contact lens material and incubation time and the interaction effect on bacterial adherence of P. aeruginosa SG81 over time Source Sum of Squares DF Mean Square F Value Sig. Contact lens material 3.276 3 1.092 28.266 < 0.001 Incubation time 9.293 2 4.646 120.278 < 0.001 Contact lens material * Incubation
time 1.569 6 0.261 6.769 < 0.001 Error 1.198 31 0.039 Corrected total 15.292 42 Although viable cell numbers significantly increased over time, learn more independent of the CL material (Table 4), distinct patterns of growth for each CL material were observed. Biofilm formation on Etafilcon A (FDA Group 4) showed a latent phase between 2 h and 4 h, followed by continuous, rapid accumulation within 24 h, a latent phase on the second day, followed by a significant growth phase on the third day. Biofilm formation on Omafilcon A (FDA Group 2) progressed through an early latent phase in the first 4 h, followed by rapid growth to a comparatively high level of adhered cells within 24 h, and last by an intermediate phase between 24 h and 72 h with significantly
decelerated growth. In contrast, biofilm formation see more on Comfilcon A (FDA Group 1) was characterised by a decrease why in growth
between 2 h and 4 h, followed by the lowest increase in growth on the first day and significant rapid growth on the second day. After 2 days, a stationary phase for biofilm formation was reached on Comfilcon A. Lotrafilcon B (FDA Group 1) also showed a decrease in growth between 2 h and 4 h, but yielded the highest initial number of adhered viable cells within 24 h growth, followed by a significant continuous increase in biofilm growth up to 48 h; a stationary phase after 2 days was also attained. Table 4 Significance of the differences between the viable cell counts of P. aeruginosa SG81 at different incubation times Contact lens material Comparison of the incubation times 24 h – 48 h 24 h – 72 h 48 h – 72 h Independent < 0.001 < 0.001 < 0.001 Etafilcon A 0.084 < 0.001 0.003 Omafilcon A 0.004 < 0.001 0.020 Comfilcon A < 0.001 < 0.001 0.435 Lotrafilcon B 0.041 0.020 0.868 Tukey’s HSD Post-hoc test. P ≤ 0.05 was considered statistically significant. A comparison of the viable cell counts associated with the test CL materials after 24 h showed no significant difference between the different CL materials (Table 5), due to the broad variance of the data. After 72 h however, variance was minimal and as a result, significant differences were observed between the viable cell counts of the various CLs. Accordingly, significantly more viable P.