Antimicrobial activities of volatile oils of Ocimum gratissimum, Eucalyptus citriodora and Cymbopogon citratus against organisms isolated from Nigerian currency notes

Naira notes are means of exchange for goods and services that may act as fomites in the transmission of pathogens. This study determined the identities of microorganisms isolated from notes and their susceptibilities to antibiotics and volatile oils of Ocimum gratissimum, Cymbopogon citratus and Eucalyptus citriodora. Fifteen notes (₦50-₦500) obtained from two Ilorin markets were soaked in sterile water and loopful of each sample was inoculated onto appropriate agar plates. Isolates were identified using standard methods, confirmed with Identification System and Mycological Atlas. Disc and agar diffusion methods were employed for susceptibility tests and positive controls were Ciprofloxacin and fluconazole. S. aureus (42%) was the most prevalent bacteria, Serratia odorifera (11.1%) including Aspergillus niger (1) while some had multiple bacteria. The isolates exhibited 100% resistance to amoxicillin/clavulanate (100%), ceftazidime (57%), sulphamethoxazole trimethoprim (43%) and 100% sensitivity to gentamicin. All S. aureus isolates were methicillin resistant – MRSA and vancomycin susceptible while A. niger exhibited 100% sensitivity to fluconazole. The volatile oil of C. citratus exhibited highest growth inhibitory effects with MBC and MIC of 3.13-0.39 and 1.56-0.39 mg/mL respectively; the oil of E. citriodora exhibited the least activity. This oil can be used as antiseptics against Naira fomites.