Inhibition ofLC554891 bySeed Extract either Singly or in Combination with Antibiotics.
Molecules. 2020 Oct 7 ;25(19). Epub 2020 Oct 7. PMID: 33036497
Bacterial outbreaks caused by() are interesting due to the existence of multidrug resistant (MDR) isolates. Therefore, there is a need to develop novel ways to control such MDR. In this study, some natural agents such as honey bee (HB), extracts of eitherseeds (MSE), or leaves (MLE) and essential oils of garlic, clove, and moringa were studied for their inhibitory activity against thispathogen. About 100 food samples including beef luncheon (= 25), potato chips (= 50), and corn flakes (= 25) were investigated for possible pollution with thebacteria. The isolated bacteria suspected to belongthat grew well onto Baird-Parker agar (Oxoid) and shiny halo zones and positive coagulase reaction were selected and identified by API-Kits; all of them that were approved belong to(18 strains). The sensitivity of the obtained 18bacterial strains to 12 antibiotics were evaluated; all of them were resistant to ofloxacin; however, other antibiotics tested showed variable results. Interestingly, theNo. B3 isolated from beef luncheon was resistant to10 antibiotics out of 12 ones tested. Multiple antibiotic resistance index (MAR) of thisstrain was about 83.3%. Therefore, its identification was confirmed by sequencing of a 16S rRNA gene which approved a successful biochemical identification carried out by API Kits and such strain was designatedLC 554891. The genome of such strain appeared to containgene encoding methicillin resistance; it was found to containandthat encodeα-blood hemolysis, β-blood hemolysis, toxic shock syndrome gene, and fibrinogen-binding protein gene, respectively. In addition, the virulence factors viz.encoding enterotoxins were detected in the DNA extracted fromB3 strain. Aqueous extract ofseeds (MSE) showed inhibitory activity againstLC 554891 better than that obtained by tetracycline, essential oils or HB. Minimum inhibitory concentration (MIC) of MSE was 20µg/mL. Instrumental analysis of MSE showed 14 bioactive chemical compounds. Combinations of both MSE and tetracycline showed distinctive inhibitory activity againstLC 554891 than that obtained by either tetracycline or MSE singly.