Nakagawa Hayate, Hattori Takaaki, Koike Naohito, Ehara Tomoko, Narimatsu Akitomo, Kumakura Shigeto, Matsumoto Tetsuya, Goto Hiroshi
Departments of *Ophthalmology, Tokyo Medical University, Tokyo, Japan; and †Microbiology, Tokyo Medical University, Tokyo, Japan.
Cornea. 2017 Mar;36(3):353-357. doi: 10.1097/ICO.0000000000001129.
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.
Acanthamoeba castellanii (ATCC50492) and P. aeruginosa (PAO-1) were used. Two densities of P. aeruginosa (high, 1 × 10/mL; low, 3 × 10/mL) and 2 durations of coincubation (long, 6 h; short, 2 h) of Acanthamoeba with 1 × 10/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.
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 < 0.01). The long (6 h) coincubation time of Acanthamoeba with high-density P. aeruginosa resulted in more severe keratitis compared with short (2 h) coincubation (scores, 9.7, 12.7, 12.1, 9.8, 8.7 vs. 7, 9.6, 8.5, 6.9, 5.6 on days 1-5, all P < 0.01).
These results suggest that the presence of bacteria is essential and a critical number of bacteria is required for the development of AK. The time of coexistence with bacteria may be an important determinant of the severity of AK.
我们推测细菌可能是棘阿米巴角膜炎（AK）发病的一个促成因素。我们研究了棘阿米巴与铜绿假单胞菌之间的相互作用对兔角膜角膜炎发病的影响。
使用卡氏棘阿米巴（ATCC50492）和铜绿假单胞菌（PAO - 1）。测试了两种密度的铜绿假单胞菌（高，1×10⁶/mL；低，3×10⁵/mL）以及棘阿米巴与1×10⁶/mL铜绿假单胞菌共孵育的两个时长（长，6小时；短，2小时）。将单独的棘阿米巴或与铜绿假单胞菌共孵育的棘阿米巴接种到兔角膜中。接种后，给予左氧氟沙星（LVFX）滴眼液。接种后评估角膜的临床评分。
在5天的观察期内，单独的棘阿米巴未引起角膜炎。接种了与低密度铜绿假单胞菌共孵育后的棘阿米巴并局部使用LVFX的兔角膜清晰，仅有少量浸润。接种了与高密度铜绿假单胞菌共孵育后的棘阿米巴并进行LVFX治疗的角膜发生了严重的角膜炎，与单独使用高密度铜绿假单胞菌并进行LVFX治疗相比，临床评分显著更高（第1 - 3天的评分分别为7、9.6、8.5与3、3.5、3.25，所有P < 0.01）。与短（2小时）共孵育相比，棘阿米巴与高密度铜绿假单胞菌长（6小时）共孵育导致更严重的角膜炎（第1 - 5天的评分分别为9.7、12.7、12.1、9.8、8.7与7、9.6、8.5、6.9、5.6，所有P < 0.01）。
这些结果表明细菌的存在是必要的，并且AK的发生需要一定数量的细菌。与细菌共存的时间可能是AK严重程度的一个重要决定因素。
