- 1Zagazig University Department of Microbiology, Faculty of Veterinary Medicine Zagazig Egypt.
- 2Zagazig University Department of Microbiology, Faculty of Veterinary Medicine Zagazig Egypt norhan_vet@hotmail.com.
- 3Zagazig University Department of Biochemistry, Faculty of Veterinary Medicine Zagazig Egypt.
Abstract
Disease
episodes of fish caused by Aeromonas species are moved to the top list
of limiting problems worldwide. The present study was planned to verify
the in vitro antibacterial activities as well as the in vivo potential
values of clove oil and ciprofloxacin against Aeromonas sobria in
African catfish (Clarias gariepinus). The in vitro phenotypic virulence
activities and the successful amplification of aerolysin and hemolysin
genes in the precisely identified A. sobria strain were predictive for
its virulence. In the in vivo assay, virulence of A. sobria strain was
fully demonstrated based on constituent mRNA expression profile of
tested virulence genes and typical septicemia associated with high
mortalities of infected fish. Apparent lower mortality rates were
correlated well with both decrescent bacterial burden and significant
down-regulated transcripts of representative genes in the treated groups
with clove oil, followed by ciprofloxacin as a prophylactic use for 15
days (P < 0.0001); however, the essential oil apart from
ciprofloxacin significantly enhanced different hematological parameters
(P < 0.05). In addition, administration of antibiotic may be considered as a pronounced stress factor in the fish even when it used in the prophylactic dose. In conclusion, medicinal plants-derived essential oils provide a virtually safer alternative to chemotherapeutics on fish, consumers and ecosystems.
