Number of Bacteria and Time of Coincubation With Bacteria Required for the Development of Acanthamoeba Keratitis

Purpose: We hypothesized that bacteria may be a factor contributing to the development of Acanthamoeba keratitis (AK). We investigated interactions between Acanthamoeba and Pseudomonas aeruginosa for the development of keratitis in rabbit corneas. Methods: Acanthamoeba castellanii (ATCC50492) and P. aeruginosa (PAO-1) were used. Two densities of P. aeruginosa (high, 1 × 108/mL; low, 3 × 105/mL) and 2 durations of coincubation (long, 6 h; short, 2 h) of Acanthamoeba with 1 × 108/mL of P. aeruginosa were tested. Acanthamoeba alone or Acanthamoeba coincubated with P. aeruginosa was inoculated into rabbit corneas. After inoculation, levofloxacin (LVFX) eye drops were administered. The clinical score of the cornea was evaluated after inoculation. Results: Acanthamoeba alone did not produce keratitis during a 5-day observation period. Rabbit corneas inoculated with Acanthamoeba coincubated with low-density P. aeruginosa followed by topical LVFX were clear with few infiltrates. Corneas inoculated with Acanthamoeba coincubated with high-density P. aeruginosa followed by LVFX treatment developed severe keratitis, and clinical scores were significantly higher compared with high-density P. aeruginosa alone followed by LVFX treatment (scores 7, 9.6, 8.5 vs. 3, 3.5, 3.25 on days 1–3, all P
Source: Cornea - Category: Opthalmology Tags: Basic Investigation Source Type: research