Antibiotic-resistant Enterobacteriaceae from diseased freshwater goldfish.

Goldfish farming gained more attention among the ornamental fishes in aquaculture industry. The occurrence of bacterial infections and further antimicrobial treatment lead to the major crisis of antibiotic resistance in aquaculture. We have isolated diverse enterobacteriaceae groups which affect the goldfish and identified their response towards 46 antimicrobials of 15 different classes. Thirteen significant bacterial isolates such as Edwardsiella tarda, Serratia marcescens, Klebsiella aerogenes, Proteus penneri, P. hauseri, Enterobacter cloacae, E. cancerogenus, E. ludwigii, Citrobacter freundii, E. coli, Kluyvera cryocrescens, Plesiomonas shigelloides and Providencia vermicola were recovered from the infected fish with the Shannon-wiener diversity index of 2.556. Multiple antibiotic resistance (MAR) index was found to be maximum for P. penneri (0.87) and minimum for C. freundii and E. cloacae (0.22), highlighting the hyper antibiotic selection pressure in the farm. The minimum concentration of antibiotics required to inhibit most of the resistant isolates was found to be > 256 mcg/ml. All the isolates were susceptible towards ciprofloxacin. Plasmid curing and further AMR tests could reveal the location of antibiotic resistance genes mainly as plasmids which determine the large extent of AMR spread through horizontal gene transfer. This study is the first of its kind to investigate the antimicrobial resistance profile of enterobacteriaceae recovered from goldfish, before and after plasmid curing.

Establishment and cryopreservation of a cell line derived from caudal fin of endangered catfish Clarias dussumieri Valenciennes, 1840.

We describe a new cell line, Clarias dussumieri fin (ClDuF), from the caudal fin of C. dussumieri using the explant technique followed by cryopreservation. The cryopreserved CiDuF cells were validated for quality and other characteristics. They showed typical epithelial morphology in vitro and epithelial cells outgrew their fibroblast cells after the fifth passage. ClDuF cells had a characteristic sigmoid curve with population doubling in 24 h. Immunotyping of the ClDuF cells against cytokeratin suggested the epithelial lineage. Chromosome analysis showed normal diploid (2n = 50) numbers and the cells did not contain any contamination, including Mycoplasma and other microbes. Partial sequencing of fragments of mitochondrial 16s rRNA and COI genes of ClDuF confirmed that the cell line was initiated from C. dussumieri. Cells at the 10th and 25th passages had more than 80% and 70% viability in the culture, respectively, after 6 months of storage at LN2 . These ClDuF cells were morphologically identical to the cells before freezing and the genetic resource of C. dussumieri was preserved. The species-specific cells can serve as a valuable source for virus isolation, conservation and cloning of somatic cells.