Molecular Identification of Multiple Antibiotic Resistant Fish Pathogenic Enterococcus faecalis and their Control by Medicinal Herbs

Abstract

The opportunistic fish pathogen, Enterococcus faecalis has been reported to cause mass mortality in several fish species in different countries. The objectives of this study were to (i) identify E. faecalis from the diseased fishes through molecular techniques; (ii) assess the antibiotic susceptibility profile of E. faecalis isolates; and (iii) control disease in tilapia fish by treatment with medicinal plant extracts. A total of 48 isolates were phenotypically identified as Enterococcus species from tilapia, stinging catfish and walking catfish cultivated in several fish farms in Gazipur. Ten randomly selected isolates were identified as E. faecalis by 16S rRNA gene sequencing. Artificial infection revealed that most of the isolates caused moderate to high mortality in fishes with characteristic disease symptoms. These isolates exhibited resistance to multiple antibiotics in vitro. Bioassay revealed that organic extracts of Tamarindus indica and Emblica officinalis leaves, Allium sativum bulb, and Syzygium aromaticum bud inhibited the growth of E. faecalis. Methanol extracts of A. sativum and methanol and acetone extracts of S. aromaticum significantly reduced the mortality of fish artificially infected with E. faecalis as both preventive and therapeutic agents. This is the first report on molecular identification, and herbal control of fish pathogenic E. faecalis in Bangladesh.

Emblica officinalis (Amla) with a Particular Focus on Its Antimicrobial Potentials: A Review

“…The organic extracts of EO leaves revealed low to moderate in-vitro antibacterial potential along with bacteriostatic activity countering several antibiotic resistant isolates of the opportunistic fish pathogen E. faecalis. 82 .…”

Dietary supplementation of garlic ( Allium sativum ) modulates gut microbiota and health status of tilapia ( Oreochromis niloticus ) against Streptococcus iniae infection

“…An overnight culture of S. iniae in nutrient broth (NB) was harvested to approximately 10 6 CFU/ml and suspended in phosphate-buffer saline (PBS) (Rahman et al, 2017). Healthy tilapia fish (12 ± 2 cm and weight 50 ± 5 g) transported in live condition from the fish farm and acclimatized for 15 days in laboratory aquaria.…”

“…bacteria. An overnight culture of S. iniae in nutrient broth (NB) was harvested to approximately 10 6 CFU/ml and suspended in phosphate-buffer saline (PBS) (Rahman et al, 2017). Fish were anaesthetized to some extent by 60 mg/L solution of MS-222 (Sigma-Aldrich, USA) and 100 μl (10 6 CFU/ml) of bacterial suspension was intramuscularly injected at the dorsal side of each fish (Garcia, Müller, Freitas & Silva, 2010;Hossain et al, 2012).…”

“…In both cases, the expression level upregulated by 2.5-2.8 fold in the second treatment compared to control. method, therefore required significant time to confirm the bacteria and to select the appropriate treatment strategies (Rahman et al, 2017). The diagnostic limitations trigger the mortality of fish in culture ponds after infection (Ulrich et al, 2017).…”

Molecular characterization and interactome analysis of aerolysin (aer) gene from fish pathogen Aeromonas veronii: The pathogenicity inferred from sequence divergence and linked to histidine kinase (cheA)

“…Several molecular tools are currently available for the characterization and interactome analysis of bacteria and associated genes in a defined network. For the characterization of bacteria and their virulence factors, polymerase chain reaction (PCR) and gene sequencing are widely used in the field of aquatic science (Rahman et al, 2017).…”