IN VITRO EFFECT OF ANTIBIOTICS AND GUAVA LEAF EXTRACT ON BACILLUS INFANTIS AND AEROMONAS JANDAEI FROM NILE TILAPIA

Abstract

In this study, the impact of antibiotics and Guava leaf extract (GLE) on the growth of bacteria isolated from the gut of Nile tilapia was investigated. Specifically, the inhibitory potential of these additives was explored for both non-pathogenic and pathogenic organisms. The antibiotic susceptibility tests showed that Aeromonas jandaei GH-AS II was resistant to Amoxicillin-Clavulanic Acid (AMC 30). Both Aeromonas jandaei GH-AS II and Bacillus infantis GH-AS II were susceptible to Penicillin (P 10). However, Bacillus infantis GH-AS II showed resistance to Tetracycline (TE 30). Both organisms were susceptible to Erythromycin (E15), Chloramphenicol (C30), and Ampicillin (AMP 10). Additionally, GLE concentrations (ranging from 10mg/ml to 100mg/ml) were tested using the agar well diffusion method. GLE inhibited the growth of both bacteria, with the zone of inhibition increased with increasing concentration. Bacillus infantis GH-SA II, zones of inhibition ranged from 15.00mm to 23.33mm, while Aeromonas jandaei GH-SA II, from 11.67mm to 21.00mm. Zones of inhibition were higher for all GLE concentrations against Bacillus infantis GH-AS II. While in vitro assays suggest that antibiotics and GLE influence the gut microflora of Nile tilapia, in vivo investigations are essential to establish their true efficacy and risks in aquaculture systems.