Antibacterial Activity of Some Essential Plant Oils Against Opportunistic Pathogenic Bacteria

Corynebacterium stationis is a facultative anaerobic gram-positive bacterium. It is an opportunistic pathogen that is one of more than 42 Corynebacterium species and subspecies found in humans, the majority of which have been linked to opportunistic illness. Human excrement, blood, and seawater are commonly used to isolate it. Mastitis in cattle is caused by the bacteria C. stationis and is characterized by inflammation of the mammary gland. Milk from the infected cows is contaminated with this bacterium, which makes it unsafe for human consumption and causes bacterial diseases in humans. In this study, the antimicrobial activity of some essential plant oils was investigated against C. stationis bacteria isolated from human feces. One bacterial isolate was identified biochemically, then characterized by 16S rRNA genotyping, and was designated as Corynebacterium stationis E. Antibiotic susceptibility testing showed resistance of C. stationis E to three antibiotics (erythromycin, clindamycin and azithromycin). Thirteen Egyptian essential plant oils were screened for their antibacterial activity; the result showed that the efficacy of black seed oil and rosemary oil against C. stationis E had an inhibition zone of 18.00 ±1.3 mm. The minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) of black seed and rosemary oils against C. stationis E were found to be 19.5 mg/L and 39 mg/L, respectively. The killing times of C. stationis E upon growth with 200 mg/L of black seed and rosemary were 6 and 7 hours, respectively.