2020, Vol. 1, Issue 2, Part A
Effect of UV light exposure on the ampicillin susceptibility and Pathogenecity of Enterococcus faecalis to Nile tilapia (Oreochromis niloticus)
Author(s): Madrid Francis Gerald N, Balagtey Lyda B, Doctolero Jemuel S and Reyes Alvin T
Abstract: The main objective of this study was to expose wild type Enterococcus faecalis via ultraviolet (UV) irradiation and to compare its antibiotic susceptibility and pathogenicity to its wild counterpart. During the 24 hours and 48 hours of incubation, the zone of inhibition (ZOI) of wild type and UV-treated E. faecalis showed significant difference among the ampicillin dosages examined (0, 5, 10, 20, 40, 60, 80, 100, 200 and 400 μg/20 μL) except at 80 μg/20 μL for 24 and 48 hours, and 200 and 400 μg/20 μL for 48 hours. As a general trend, the wild type E. faecalis had higher ZOI as compared to the UV-treated E. faecalis at the majority of ampicillin dosages. Both the wild and UV-treated bacterium was classified as intermediate at 5 μg/20 μL and susceptible in the rest of ampicillin dosages according to the classification of Clinical Laboratory Standard Institute. In general, there was no difference in the minimum inhibitory concentration (MIC) of wild and UV-treated E. faecalis. Ampicillin with a breakpoint of 5 μg/20 μL was comparable with the results obtained in Kirby-Baeur method in which both isolates were classified as susceptible for as low as 5 μg/20 μL. It was also proven that the commensal E. faecalis can cause diseases or even death (40% mortality) to cultured tilapia at the density of 108 cells/mL. The gross signs of the enterococossis have appeared as early as day 2 post-inoculation (PI) and began to cause death after day 5 PI.
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How to cite this article:
Madrid Francis Gerald N, Balagtey Lyda B, Doctolero Jemuel S, Reyes Alvin T. Effect of UV light exposure on the ampicillin susceptibility and Pathogenecity of Enterococcus faecalis to Nile tilapia (Oreochromis niloticus). Acta Entomol Zool 2020;1(2):20-28. DOI: 10.33545/27080013.2020.v1.i2a.14