Antibiotic susceptibility pattern of fish pathogens: A new approach of emerging the bacterial resistance through biofilm formation in in-vitro condition.

• Different fishes were collected and were subjected to form an in vitro biofilm. • Huge array (up to 10⁷ cfu/ml or g) of pathogenic bacteria. • Few of the isolates were sensitive and few were resistant against the antibiotics but after bio-film formation all the species acquired resistance. The ability of many bacteria to adhere on the host surfaces and forming biofilms has major implications in a wide variety of industries including the food industry, where biofilms may create a persistent source of contamination. In the same environmental condition, the multiple bacterial species can closely interact with each other and may easily enhance their drug resistance capability, which finally increases the multi-drug resistant (MDR) attribute of the species. The present study examined whether the mixed-species biofilm possesses any impact on the enhancement of the antibiotic resistance of the planktonic or single-cell bacterial isolates present in the fish samples. In this regard, Cyprinus rubrofuscus (Koi) , Heteropneustes fossilis (Shing) and Mystus vittatus (Tengra) fishes were collected and subjected to form an in vitro biofilm by shaking condition into the wise bath. The drug-resistant pattern was determined by the Kirby Bauer technique. All the samples exhibited a huge array (up to 10⁷ cfu/ml or g) of bacteria such as E. coli , Klebsiella spp., Vibrio spp., Salmonella spp., Proteus spp. and Staphylococcus spp. The isolates from both the bulk samples and their corresponding biofilms were subjected to antibiogram assay using antibiotics such as Ampicillin (10 µg), Erythromycin (15 μg), Streptomycin (STP 10 μg), Oxacillin (10 µg), Nalidixic acid (30 µg). Before biofilm formation, few of the isolates were found to be sensitive and few were resistant against the antibiotics. But when the species were isolated from the biofilm the sensitive one acquired drug resistance and resistant strain unveiled more resistance towards the same antibiotics. The present study revealed extensive bacterial contamination in fish samples among those some were resistant against the supplied drugs. After the formation of multi-species biofilm, the isolates became more resistant against the same drugs that is alarming for consumers and major obstacles to maintain sustainable health. [ABSTRACT FROM AUTHOR]