Original scientific paper

Bacterial flora from a healthy freshwater Asian sea bass (Lates calcarifer) fingerling hatchery with emphasis on their antimicrobial and heavy metal resistance pattern

Lee S. Wei orcid.org/0000-0002-4854-2621 ; Department of Agro Industry, Faculty of Agro Industry and Natural Resources, Universiti Malaysia Kelantan, Pengkalan Chepa, Kota Bharu, Kelantan, Malaysia
Najiah Musa ; Department of Fishery and Aquaculture, Faculty of Agrotechnology and Food Science, Universiti Malaysia Terengganu, Kuala Terengganu, Terengganu, Malaysia
Wendy Wee orcid.org/0000-0002-4399-8937 ; Department of Fishery and Aquaculture, Faculty of Agrotechnology and Food Science, Universiti Malaysia Terengganu, Kuala Terengganu, Terengganu, Malaysia

Abstract

This paper describes bacterial flora, the antimicrobial and heavy metal resistance pattern of bacteria isolated from a commercial freshwater Asian sea bass (Lates calcarifer) fingerling hatchery in Terengganu, Malaysia. This study was carried out to provide information on bacterial flora which can be isolated from water samples of freshwater Asian sea bass as well as its antimicrobial and heavy metal resistance pattern. This information may useful for fish farmers for treatment and prophylactic purposes. In the present study, bacteria were isolated from 26 freshwater sea bass fingerling tank water samples using Tryptic Soy Agar (TSA), Mac Conkey Agar, Thiosulphate Citrate Bile Salt Agar (TCBS), Eosin Methylene Blue Agar (EMB), Glutamate Starch Pseudomonas Agar (GSP), Xylose Lysine Deoxycholate Agar (XLD) and Baird Parker Agar. Bacterial identification was conducted using conventional biochemical tests and confirmed with a commercial bacterial identification kit. The antimicrobial resistance pattern of isolated bacteria was established using a disk diffusion method whereas the heavy metal resistance pattern (mercury, cadmium, chromium and copper) was determined using two fold agar dilution method. The results of the present study showed that Aeromonas spp. (n = 16), Escherichia coli (n = 20), Edwardsiella tarda (n = 8), Pseudomonas spp. (n = 20), Salmonella spp. (n = 24) and Vibrio spp. (n = 20) were successfully isolated and identified. The total colony forming unit (CFU) of bacteria
on Tryptic Soy Agar (TSA), Mac Conkey Agar, Thiosulphate Citrate Bile Salt Agar (TCBS), Eosin Methylene Blue Agar (EMB), Glutamate Starch Pseudomonas Agar (GSP), Xylose Lysine Deoxycholate Agar (XLD) and Baird Parker Agar ranged from 1×10^5 to 2.6×10^7 CFU/mL. Overall, the multiple antibiotic resistance (MAR) index indicated that water samples were no under high risk exposure to the tested antibiotics. The antibiotic
susceptibility test of bacterial isolates to 17 antibiotics (oxolinic acid 2 μg, ampicillin 10 μg, erythromycin 15 μg, lincomycin 15 μg, oleandomycin 15 μg, amoxicillin 25 μg, sulphamethoxazole 25 μg, chloramphenicol 30 μg, doxycycline 30 μg, fl orfenicol 30 μg, fl umequine 30 μg, fosfomycin (50 μg), kanamycin 30 μg, nalidixic acid 30 μg, tetracycline 30 μg, nitrofurantoin 50 μg and spiramycin 100 μg) showed that 75.2% were reported as sensitive cases whereas 19.4% and 5.4% were resistant and intermediately sensitive cases. More than 90% of the bacterial isolates were sensitive to chloramphenicol, kanamycin, oxolinic acid, fl orfenicol, nitrofurantoin, flumequine, fosfomycin, tetracycline and doxycycline. On the other hand, all bacterial isolates were resistant to all tested heavy metals except for copper (13.8%).

Keywords

freshwater Asian Seabass; Lates calcarifer fingerling; antibiotic; heavy metal

Hrčak ID:

58456

URI

https://hrcak.srce.hr/58456

Publication date:

16.6.2010.

Article data in other languages: croatian

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