Find in Library

Bacterial outbreaks caused by <i>Staphylococcus aureus</i> (<i>S. aureus</i>) are interesting due to the existence of multidrug resistant (MDR) isolates. Therefore, there is a need to develop novel ways to control such MDR <i>S. aureus</i>. In this study, some natural agents such as honey bee (HB), extracts of either <i>Moringa oleifera</i> seeds (MSE), or leaves (MLE) and essential oils of garlic, clove, and moringa were studied for their inhibitory activity against this <i>S. aureus</i> pathogen. About 100 food samples including beef luncheon (<i>n</i> = 25), potato chips (<i>n</i> = 50), and corn flakes (<i>n</i> = 25) were investigated for possible pollution with the <i>S. aureus</i> bacteria. The isolated bacteria suspected to belong <i>S. aureus</i> that 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 <i>S. aureus</i> (18 strains). The sensitivity of the obtained 18 <i>S. aureus</i> bacterial strains to 12 antibiotics were evaluated; all of them were resistant to ofloxacin; however, other antibiotics tested showed variable results. Interestingly, the <i>S. aureus</i> No. B3 isolated from beef luncheon was resistant to 10 antibiotics out of 12 ones tested. Multiple antibiotic resistance index (MAR) of this <i>S. aureus</i> strain 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 designated <i>S. aureus</i> LC 554891. The genome of such strain appeared to contain <i>mecA</i> gene encoding methicillin resistance; it was found to contain <i>hla, hlb, tsst-1,</i> and <i>finbA</i> that encode α-blood hemolysis, β-blood hemolysis, toxic shock syndrome gene, and fibrinogen-binding protein gene, respectively. In addition, the virulence factors viz. <i>sea; seb; sec</i> encoding enterotoxins were detected in the DNA extracted from <i>S. aureus</i> B3 strain. Aqueous extract of <i>Moringa oleifera</i> seeds (MSE) showed inhibitory activity against <i>S. aureus</i> LC 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 against <i>S. aureus</i> LC 554891 than that obtained by either tetracycline or MSE singly.