Characterization of the bacterial flora of tilapia (Oreochoromis niloticus) harvested from four lakes in the north of Cameroon

Abstract

The aim of this study was to investigate the presence of Aeromonas spp., Vibrio spp. and Plesiomonas shigelloides in Cameroonian tilapia.120 samples of tilapia were collected from June to December 2005 in four localities in the north of Cameroon and were delivered to the laboratory in cool boxes. For the sample preparation to isolate the bacteria, 50 g of sample (gills, intestine and skin of individually fish) were taken using a sterile scalpel. These 50 g were homogenized in 450 ml of sterilised peptone solution. After 18 h of incubation, the homogenate sample was inoculated on thiosulphate citrate bile salt sucrose (TCBS) using an inoculation loop and incubated at 37°C for 18 to 24 h. The isolated colonies were subjected to morphological, physiological and commercially available API kits tests. In addition, the antimicrobial pattern of the identified strains to ten different antibiotics was studied using the agar disk diffusion method. The results obtained from this study show the presence of bacterial species belonging to Aeromonas spp. (n=39), Vibrio spp. (n=41) and P. shigelloides (n=14). The results of antimicrobial susceptibility show that the highest rates of resistance was found in ampicillin (100% of isolates), nitrofurantoin (more than 68% of isolates), association of trimethoprim and sulfamethoxazole (51% of isolates) and sulfamide (46 % of isolates). This work therefore highlights an important incidence of Aeromonas spp., Vibrio spp. and P. shigelloides with potential antimicrobial resistance, isolated from tilapia in four localities of Cameroon.