title: Potential of Psidium guajava supplemented fish diets in controlling Aeromonas hydrophila infection in tilapia (Oreochromis niloticus).
abstract: Fourteen herbs were extracted in water, 95% ethanol, and ether, and tested in vitro for antimicrobial activities against Aeromonas hydrophila, a fish pathogen causing motile Aeromonas septicemia. Using swab paper disc assays and minimal inhibitory concentration (MIC) determinations, we noted that the ethanol extract of Psidium guajava leaf exhibited the strongest antimicrobial activity. The extract allowed growth-inhibited A. hydrophila cells to regrow in fresh BHI broth indicating a bacteriostatic mode of action. In a pathogenicity test, the median lethal dose (LD(50)) of A. hydrophila for tilapia (Oreochromis niloticus) by intraperitoneal injection was 3.44 x 10(6) CFU/ml. In vivo experiments showed that fish diets containing either dry leaf powder of P. guajava or dried ethanol extract of P. guajava leaf reduced mortality of A. hydrophila infected tilapia with no detected adverse effect on the fish. This study suggests that P. guajava leaf has the potential to control fish diseases caused by A. hydrophila.
authors.affiliation: Department of Biological Science, Faculty of Science, Ubon Ratchathani University, Warin Chamrap, Ubon Ratchathani, Thailand.
authors.forename: Adithepchaikarn
authors.initials: A
authors.lastname: Pachanawan
authors.forename: Parichat
authors.initials: P
authors.lastname: Phumkhachorn
authors.forename: Pongsak
authors.initials: P
authors.lastname: Rattanachaikunsopon
mesh_terms: D000284:Administration, Oral; D016980:Aeromonas hydrophila / Q000502:physiology*; D000821:Animal Feed; D000818:Animals; D000890:Anti-Infective Agents / Q000494:pharmacology; D023681:Cichlids / Q000502:physiology*; D019587:Dietary Supplements; D000431:Ethanol / Q000737:chemistry; D005399:Fishes; D018515:Plant Leaves; D031647:Psidium / Q000378:metabolism*; D013696:Temperature; D013997:Time Factors
chemical_list: D000890:Anti-Infective Agents; D000431:Ethanol