Abstract:
Antibacterial activity of crude extracts of two Allium species namely Allium cepa Linn (onion) and
Allium aescalonicum Linn (shallot) cultivated in Ghana was investigated on isolates of Escherichia coli
(ATCC 25922), Staphylococcus aureus (ATCC 25923), and Salmonella typhi (ATCC 19430) by the
agar well diffusion method. Broth cultures of the test bacterial isolates were standardised to 0.5
McFarland (1.0 × 106 cfu/ml) and seeded on nutrient agar. Crude extracts of the onions and shallots
were prepared from samples bought from the market. 75µl of undiluted and diluted crude extracts were
introduced into corresponding agar wells and incubated at room temperature (approximately 37 °C) for
susceptibility test. 15µg/mL of Ciprofloxacin was set as control. After 24 hours of incubation, zones of
inhibition were measured and recorded in millimetres. The undiluted extracts exhibited greater
inhibitory activity on the test organisms than the diluted extracts. Salmonella typhi was observed to be
susceptible to the crude extracts though resistant to ciprofloxacin. Diluting crude extracts of both onion
and shallot beyond 1:2 dilution had no antibacterial action on the isolates. Further research is
recommended on the pharmacokinetics of the active components in the crude extracts. Eating raw
onions and shallots should be encouraged.
