The research was designed to evaluate the efficacy of methanolic and aqueous extracts of Nigella sativa, Black seed oil and thymoquinone against antibiotic resistant molecular characterized Salmonella enterica isolates of human and poultry origin (n=5 each). The compounds that have shown the antibacterial activity was also checked for their cytotoxicity by MTT assay.
Salmonella is causative agent of invasive diseases in poultry and humans, results in high mortality. Salmonellosis is a disease caused by Salmonella enterica with serious health issues related to food borne illness and most of world’s population is suffering from it. Mostly infections are treated by antibiotics but now a day’s resistance developed by Salmonella enterica. So it is need of time to develop some alternate ways to combat the problem caused by resistant bacterial pathogens. Use of essential oils and extracts of seeds are good weapons against resistant bacteria.
Salmonella enterica isolates of human and poultry origin (n=5 each) were taken from Department of microbiology UVAS Lahore and identified by colony morphology, microscopic characters, biochemical testing (Indole production test, Methyl red test, Voges Proskaeur test, Citrate utilization test and Urea utilization test) and polymerase chain reaction (PCR). For PCR product 1.5% agarose gel was run by gel electrophoresis. The biochemically identified and molecular characterized S. enterica isolates were screened for antibiotic susceptibility by Kirby Bauer disc diffusion method against amoxicillin, ampicillin, cefixime, ceftriaxone, ciprofloxacin, gentamicin, nalidixic acid, co-trimoxazole, ofloxacin and tetracycline and resistant pattern was 100% against ampicillin and Nalidixic acid and isolates shown 60% resistant against co-trimoxazole, amoxicillin and tetracycline, 80% and 40% resistant found against ofloxacin and ciprofloxacin while all isolates sensitive to cefixime and ceftriaxone. Aqueous and methanol were
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SUMMARY
used as solvents for extraction from Nigella Sativa. Seeds were dried, mixed, centrifuged, filtered and filtrate evaporated to obtained extracts. Percentage yield of methanolic extract was more than aqueous extract. Commercially available black seed oil, thymoquinone, water and methanol extracts of black seed would be evaluated for antibacterial activity by well diffusion method. Zones were measured in millimeters. All compounds gave the zones of inhibition except aqueous extract against Salmonella enterica isolates. The minimum inhibitory concentration (MIC) was determined by micro broth dilution method and then methanolic extract, black seed oil and thymoquinone used in MTT assay to evaluate their cytotoxicity. Cell survival percentage was calculated by a formula.
Data were analyzed by one way analysis of variance (ANOVA) followed by Duncan’s multiple range tests (DMRT) using statistical package for social sciences (SPSS version 20.0). Antimicrobial activity of essential oils, thymoquinone, water and methanol extract would be compared by graph pad prism 5.0 statistical software.