Abstract
Purpose :
Antibiotic resistant microorganisms are an increasing cause for concern in hospitals around the world. In an attempt to find innovative approaches to control antibiotic resistant bacteria, we tested whether predatory bacteria could successfully influence the viability of an ocular isolate of fluoroquinolone-resistant Pseudomonas aeruginosa (PA) in the rabbit vitreous.
Methods :
The vitreous of the right eyes of NZW rabbits were inoculated with 5000 CFU of PA in 25 µl. Immediately after inoculation, 100 µl containing 3.2x109 CFU of Bdellovibrio bacteriovorus strain HD100 (BD) (n=6) or 2.5x108 Micavibrio aeruginosavorus strain ARL-13 (MICA) (n=5), or PBS (n=7) were injected into the vitreous. After 24 hours, the vitreous was sampled for standard colony count determinations as well as IL-1β and TNF-α production by ELISA
Results :
Both BD (5.18 - median Log10 colony counts; 4.59-5.70 - 95% Confidence Interval) and MICA (5.27; 5.03-5.48) significantly reduced the number of PA able to grow in the vitreous compared to PBS (6.68; 5.99-7.20) (p<0.05, Kruskal-Wallis). There was no difference in colony counts between BD and MICA (p>0.05 K-W). Similarly, BD (1525 ± 1516 pg/ml) and MICA (685.5 ± 445.1 pg/ml) significantly decreased IL-1β production compared with PBS (4358 ± 1575 pg/ml) (p<0.001, ANOVA). There was no difference in IL-1β production between BD and MICA (p>0.05, ANOVA). There were also no significant differences in TNF-α production among BD (462.7 ± 210.6 pg/ml), MICA (422.9 ± 154.4 pg/ml), and PBS (605.3 ± 390.1 pg/ml) (p>0.05, ANOVA).
Conclusions :
Treatment of an intraocular fluoroquinolone-resistant Pseudomonas aeruginosa infection with the predatory bacteria BD and MICA significantly reduced the number of PA able to grow in the vitreous compared to PBS. Similarly, BD and MICA significantly reduced the production of IL-1β suggesting a reduction in acute tissue injury. These efficacy data offer a “Proof of Principle” suggesting that these bacteria devouring microbes could be developed as alternative therapy for eye infections when antibiotics fail.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.